Motor parameter determination method and device, electric appliance system, storage medium and processor

文档序号：1115823 发布日期：2020-09-29 浏览：9次中文

阅读说明：本技术 电机参数确定方法、装置、电器系统、存储介质及处理器 (Motor parameter determination method and device, electric appliance system, storage medium and processor ) 是由刘涛陶海莉黄伟于 2020-07-10 设计创作，主要内容包括：本发明公开了一种电机参数确定方法、装置、电器系统、存储介质及处理器,该方法包括：在电机静止的情况下,向电机施加设定的脉冲电压,确定电机的电感参数,以根据不同电流下的电感参数得到电感与电流的对应关系；其中,所述设定的脉冲电压中,电压幅值大于或等于设定幅值、且作用时长小于或等于设定时长；所述电机参数,包括：电机的电感参数；所述电感参数,包括：直轴电感和交轴电感；所述直轴电感,包括：直轴静态电感和直轴动态电感；所述交轴电感,包括：交轴静态电感和交轴动态电感。本发明的方案,可以解决利用电机的理性模型识别电机参数的准确性较低的问题,达到提升对电机参数确定的准确性的效果。(The invention discloses a motor parameter determination method, a device, an electric appliance system, a storage medium and a processor, wherein the method comprises the following steps: under the condition that the motor is static, applying set pulse voltage to the motor, determining inductance parameters of the motor, and obtaining a corresponding relation between inductance and current according to the inductance parameters under different currents; in the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action duration is less than or equal to the set duration; the motor parameters include: inductance parameters of the motor; the inductance parameter comprises: a direct axis inductor and a quadrature axis inductor; the direct axis inductor includes: a direct-axis static inductor and a direct-axis dynamic inductor; the quadrature axis inductance includes: quadrature static inductance and quadrature dynamic inductance. According to the scheme, the problem of low accuracy of identifying the motor parameters by using the rational model of the motor can be solved, and the effect of improving the accuracy of determining the motor parameters is achieved.)

1. A method for determining motor parameters, the motor parameters comprising: inductance parameters of the motor; the motor parameter determination method comprises the following steps:

under the condition that the motor is static, applying set pulse voltage to the motor, determining inductance parameters of the motor, and obtaining a corresponding relation between inductance and current according to the inductance parameters under different currents;

wherein the content of the first and second substances,

in the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action duration is less than or equal to the set duration;

the motor parameters include: inductance parameters of the motor; the inductance parameter comprises: a direct axis inductor and a quadrature axis inductor; the direct axis inductor includes: a direct-axis static inductor and a direct-axis dynamic inductor; the quadrature axis inductance includes: quadrature static inductance and quadrature dynamic inductance.

2. The motor parameter determination method of claim 1, wherein the set pulse voltage comprises: a series of pulse voltages and groups of pulse voltages;

the method for applying the set pulse voltage to the motor and determining the inductance parameter of the motor comprises the following steps:

applying a series of pulse voltages to the motor to determine the initial position of a rotor of the motor;

enabling the position of the rotor to be 0 degree, applying a pulse voltage group to the direct axis, and determining the direct axis inductance;

enabling the rotor position to be 90 degrees, applying a pulse voltage group to a quadrature axis, and determining quadrature axis inductance;

the rotor positions were taken at angles other than 0 and 90 degrees, and groups of pulsed voltages were applied to determine the cross-coupled inductance.

3. The motor parameter determination method of claim 2, wherein,

the applying a series of pulse voltages to the motor to determine an initial position of a rotor of the motor comprises:

sequentially increasing a pulse voltage application mode of a set electrical angle according to the voltage vector angle each time, applying a series of pulse voltages to the motor, and recording the current peak value and the corresponding angle after the pulse voltage is applied each time;

under the angle corresponding to the maximum current value in all the recorded current peak values, continuously applying pulse voltage and gradually increasing the voltage amplitude of the pulse voltage until the current peak value reaches a preset value and then closing the pulse voltage; repeating the operation and continuing for a set time, and taking the angle corresponding to the maximum current value as the initial position of the rotor of the motor;

and/or the presence of a gas in the gas,

the pulse voltage group comprises: four pulses in positive and negative directions; each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector magnitude and duration of control voltage and is realized by duty ratio signals of a bridge arm of an inverter circuit for controlling the motor; the second part of pulse is to control the disappearance speed of the current and is realized by blocking a bridge arm of an inverter circuit of the control motor.

4. The motor parameter determination method of claim 2, wherein,

the applying of the pulse voltage group to the direct axis to determine the direct axis inductance comprises the following steps:

after a first group of pulse voltages are applied to the direct axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of direct axis inductance according to the magnetic flux; sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain direct-axis inductors under different current levels;

and/or the presence of a gas in the gas,

the applying of the pulse voltage group to the quadrature axis to determine the quadrature axis inductance comprises:

after a first group of pulse voltages are applied to the quadrature axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of quadrature axis inductance according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the quadrature axis inductance under different current levels.

5. The motor parameter determination method of claim 4, wherein the determining a magnetic flux of the motor comprises:

calculating the magnetic flux of the motor according to the following formula:

wherein u is the amplitude of the voltage vector in time, i is the phase current of the motor, r is the phase resistance of the motor, u is the phase resistance of the motor_deadFor dead-zone voltages, T, caused by the dead-zone effect of the inverter_sIs the PWM switching period.

6. The motor parameter determination method of claim 4, wherein the determining a first set of direct axis inductances from the magnetic flux comprises: determining a direct-axis static inductance and determining a direct-axis dynamic inductance;

the determining a first set of quadrature axis inductances from the magnetic flux comprises: determining quadrature axis static inductance and determining quadrature axis dynamic inductance;

wherein the content of the first and second substances,

in the determining the direct-axis static inductance and/or determining the quadrature-axis static inductance, determining the static inductance includes:

calculating the corresponding static inductance according to the following formula:

the method comprises the following steps that A, a position angle of a motor rotor is theta, and i is the motor current under the current motor rotor angle;

and/or the presence of a gas in the gas,

in the determining of the direct-axis dynamic inductance and the determining of the quadrature-axis dynamic inductance, determining the dynamic inductance includes:

fitting a relation curve of the inductance and the current according to the direct axis inductance under the different current levels and the quadrature axis inductance under the different current levels, and calculating to obtain the dynamic inductance by combining the following formula:

wherein i_dIs the direct axis current of the motor i_qIs motor quadrature axis current, L'_d(i_d) Is the current direct-axis dynamic inductance, L, of the motor_d(i_d) Is the current direct-shaft static inductance of the motor, L'_q(i_q) Is the current quadrature axis dynamic inductance, L, of the motor_q(i_q) The static inductance of the current direct axis of the motor is shown as d, the subscript of the direct axis of the motor is shown as q, the subscript of the quadrature axis of the motor is shown as k, the power number of the inductive current fitting polynomial is shown as k, and a is the coefficient of the inductive current fitting polynomial.

7. The motor parameter determination method of claim 1, wherein the motor parameter further comprises: a stator resistance of the motor; the motor parameter determination method further comprises the following steps:

applying pulse voltage in the direction of a straight shaft of the motor until the current after the pulse voltage is applied reaches a set degree, and recording the current;

applying a zero voltage vector to attenuate the current to obtain an integral value of the current with respect to time;

and calculating the stator resistance of the motor according to the following formula by combining the inductance parameter of the motor:

wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

8. The motor parameter determination method of any of claims 1-7, further comprising:

under the condition that the motor runs, obtaining the running current of the motor;

and on the basis of the determined motor parameters, according to the running current, predetermining target control parameters of the motor so as to control the running process of the motor according to the target control parameters.

9. A motor parameter determination apparatus, wherein the motor parameter includes: inductance parameters of the motor; the motor parameter determination apparatus includes:

the determining unit is used for applying set pulse voltage to the motor under the condition that the motor is static, determining inductance parameters of the motor and obtaining the corresponding relation between the inductance and the current according to the inductance parameters under different currents;

wherein the content of the first and second substances,

in the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action duration is less than or equal to the set duration;

10. The motor parameter determination device of claim 9, wherein the set pulse voltage comprises: a series of pulse voltages and groups of pulse voltages;

the determining unit applies the set pulse voltage to the motor and determines the inductance parameter of the motor, and the determining unit comprises the following steps:

applying a series of pulse voltages to the motor to determine the initial position of a rotor of the motor;

enabling the position of the rotor to be 0 degree, applying a pulse voltage group to the direct axis, and determining the direct axis inductance;

enabling the rotor position to be 90 degrees, applying a pulse voltage group to a quadrature axis, and determining quadrature axis inductance;

the rotor positions were taken at angles other than 0 and 90 degrees, and groups of pulsed voltages were applied to determine the cross-coupled inductance.

11. The motor parameter determination apparatus of claim 10, wherein,

the determining unit applies a series of pulse voltages to the motor and determines an initial position of a rotor of the motor, including:

and/or the presence of a gas in the gas,

the pulse voltage group comprises: four pulses in positive and negative directions; each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector magnitude and duration of control voltage and is realized by duty ratio signals of bridge arms of a rectification and inversion circuit for controlling a motor; the second part of pulse is to control the disappearance speed of the current and is realized by blocking a bridge arm of an inverter circuit of the control motor.

12. The motor parameter determination apparatus of claim 10, wherein,

the determining unit applies a pulse voltage group to the direct axis to determine the direct axis inductance, and comprises:

and/or the presence of a gas in the gas,

the determining unit applies a pulse voltage group to the quadrature axis to determine quadrature axis inductance, and comprises:

13. The motor parameter determination device of claim 12, wherein the determination unit determines a magnetic flux of the motor, comprising:

calculating the magnetic flux of the motor according to the following formula:

wherein u is the amplitude of the voltage vector in time, i is the phase current of the motor, r is the resistance of the motor, u is the amplitude of the voltage vector in time_deadFor dead-zone voltages, T, caused by the dead-zone effect of the inverter_sIs the PWM switching period.

14. The motor parameter determination device of claim 12, wherein the determination unit determines a first set of direct axis inductances from the magnetic flux, comprising: determining a direct-axis static inductance and determining a direct-axis dynamic inductance;

the determining unit determines a first set of quadrature axis inductances from the magnetic flux, including: determining quadrature axis static inductance and determining quadrature axis dynamic inductance;

wherein the content of the first and second substances,

the determining unit determines static inductance in direct-axis static inductance and/or quadrature-axis static inductance, and the determining unit includes:

calculating the corresponding static inductance according to the following formula:

wherein, theta is the position of the motor rotor, and i is the current of the motor at the current angle;

and/or the presence of a gas in the gas,

the determining unit determines the dynamic inductance in the direct-axis dynamic inductance and the quadrature-axis dynamic inductance, and the determining unit comprises the following steps:

15. The motor parameter determination device of claim 9, wherein the motor parameter further comprises: a stator resistance of the motor; the motor parameter determination device further comprises:

applying pulse voltage in the direction of a straight shaft of the motor until the current after the pulse voltage is applied reaches a set degree, and recording the current;

applying a zero voltage vector to attenuate the current to obtain an integral value of the current with respect to time;

and calculating the stator resistance of the motor according to the following formula by combining the inductance parameter of the motor:

wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

16. The motor parameter determination device according to any one of claims 9 to 15, further comprising:

the acquisition unit is used for acquiring the running current of the motor under the condition that the motor runs;

the determining unit is further configured to determine a target control parameter of the motor in advance according to the operating current based on the determined motor parameter, so as to control an operating process of the motor according to the target control parameter.

17. An air conditioning system, comprising: the motor parameter determination apparatus of any of claims 9 to 16.

18. A storage medium, characterized in that the storage medium comprises a stored program, wherein the program, when executed, controls an apparatus in which the storage medium is located to perform the motor parameter determination method according to any one of claims 1 to 8.

19. A processor, characterized in that the processor is configured to run a program, wherein the program is configured to perform the method of determining a parameter of an electric machine of any of claims 1 to 8 when running.

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a motor parameter determination method, a motor parameter determination device, an electric appliance system, a storage medium and a processor, in particular to a permanent magnet synchronous motor parameter identification method, a permanent magnet synchronous motor parameter identification device, an air conditioner system, a refrigerator, a washing machine and other household appliances using a permanent magnet synchronous motor, a storage medium and a processor.

Background

The permanent magnet synchronous motor has the advantages of high power density, wide speed regulation range, high efficiency, small volume, quick response, reliable operation and the like, and is widely applied to alternating current driving occasions such as household appliances, numerical control machines, industrial robots, electric automobiles, aviation equipment and the like.

In order to obtain a high-performance control effect, motor parameters need to be identified in the running process of the permanent magnet synchronous motor. In some motor parameter determination methods, the ideal model of the motor is mostly considered to be used for identifying the motor parameters, but the rational model of the motor and the actual parameters have certain difference, so that the accuracy of determining the motor parameters is influenced.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a motor parameter determination method, a motor parameter determination device, an electric appliance system, a storage medium and a processor, aiming at the defects, so as to solve the problem of low accuracy of identifying motor parameters by using a rational model of a motor and achieve the effect of improving the accuracy of determining the motor parameters.

The invention provides a motor parameter determination method, wherein the motor parameter comprises the following steps: inductance parameters of the motor; the motor parameter determination method comprises the following steps: under the condition that the motor is static, applying set pulse voltage to the motor, determining inductance parameters of the motor, and obtaining a corresponding relation between inductance and current according to the inductance parameters under different currents; in the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action duration is less than or equal to the set duration; the motor parameters include: inductance parameters of the motor; the inductance parameter comprises: a direct axis inductor and a quadrature axis inductor; the direct axis inductor includes: a direct-axis static inductor and a direct-axis dynamic inductor; the quadrature axis inductance includes: quadrature static inductance and quadrature dynamic inductance.

Optionally, the set pulse voltage includes: a series of pulse voltages and groups of pulse voltages; the method for applying the set pulse voltage to the motor and determining the inductance parameter of the motor comprises the following steps: applying a series of pulse voltages to the motor to determine the initial position of a rotor of the motor; enabling the position of the rotor to be 0 degree, applying a pulse voltage group to the direct axis, and determining the direct axis inductance; enabling the rotor position to be 90 degrees, applying a pulse voltage group to a quadrature axis, and determining quadrature axis inductance; the rotor positions were taken at angles other than 0 and 90 degrees, and groups of pulsed voltages were applied to determine the cross-coupled inductance.

Optionally, wherein the applying a series of pulse voltages to the motor to determine an initial position of a rotor of the motor comprises: sequentially increasing a pulse voltage application mode of a set electrical angle according to the voltage vector angle each time, applying a series of pulse voltages to the motor, and recording the current peak value and the corresponding angle after the pulse voltage is applied each time; under the angle corresponding to the maximum current value in all the recorded current peak values, continuously applying pulse voltage and gradually increasing the voltage amplitude of the pulse voltage until the current peak value reaches a preset value and then closing the pulse voltage; repeating the operation and continuing for a set time, and taking the angle corresponding to the maximum current value as the initial position of the rotor of the motor; and/or, the pulse voltage group comprises: four pulses in positive and negative directions; each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector magnitude and duration of control voltage and is realized by duty ratio signals of bridge arms of a rectification and inversion circuit for controlling a motor; the second part of pulse is to control the disappearance speed of the current and is realized by blocking a bridge arm of an inverter circuit of the control motor.

Optionally, wherein the applying a set of pulsed voltages on the direct axis to determine the direct axis inductance comprises: after a first group of pulse voltages are applied to the direct axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of direct axis inductance according to the magnetic flux; sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain direct-axis inductors under different current levels; and/or, the applying a pulse voltage group to the quadrature axis to determine the quadrature axis inductance comprises: after a first group of pulse voltages are applied to the quadrature axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of quadrature axis inductance according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the quadrature axis inductance under different current levels.

Optionally, the determining a magnetic flux of the electric machine comprises: calculating the magnetic flux of the motor according to the following formula:wherein u is the amplitude of the voltage vector in time, i is the phase current of the motor, r is the resistance of the motor, u is the amplitude of the voltage vector in time_deadFor dead-zone voltages, T, caused by the dead-zone effect of the inverter_sIs the PWM switching period.

Optionally, the determining a first set of direct axis inductances from the magnetic flux comprises: determining a direct-axis static inductance and determining a direct-axis dynamic inductance; the determining a first set of quadrature axis inductances from the magnetic flux comprises: determining quadrature axis static inductance and determining quadrature axis dynamic inductance; wherein, in the determining of the direct-axis static inductance and/or determining of the quadrature-axis static inductance, determining the static inductance includes: calculating the corresponding static inductance according to the following formula:

the method comprises the following steps that A, a position angle of a motor rotor is theta, and i is the motor current under the current motor rotor angle;

and/or in the determining of the direct-axis dynamic inductance and the determining of the quadrature-axis dynamic inductance, determining the dynamic inductance comprises the following steps: fitting a relation curve of the inductance and the current according to the direct axis inductance under the different current levels and the quadrature axis inductance under the different current levels, and calculating to obtain the dynamic inductance by combining the following formula:

Optionally, the motor parameter further includes: a stator resistance of the motor; the motor parameter determination method further comprises the following steps: applying pulse voltage in the direction of a straight shaft of the motor until the current after the pulse voltage is applied reaches a set degree, and recording the current; applying a zero voltage vector to attenuate the current to obtain an integral value of the current with respect to time; and calculating the stator resistance of the motor according to the following formula by combining the inductance parameter of the motor:

wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

Optionally, the method further comprises: under the condition that the motor runs, obtaining the running current of the motor; and on the basis of the determined motor parameters, according to the running current, predetermining target control parameters of the motor so as to control the running process of the motor according to the target control parameters.

In accordance with the above method, another aspect of the present invention provides a motor parameter determining apparatus, where the motor parameter includes: inductance parameters of the motor; the motor parameter determination apparatus includes: the determining unit is used for applying set pulse voltage to the motor under the condition that the motor is static, determining inductance parameters of the motor and obtaining the corresponding relation between the inductance and the current according to the inductance parameters under different currents; in the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action duration is less than or equal to the set duration; the motor parameters include: inductance parameters of the motor; the inductance parameter comprises: a direct axis inductor and a quadrature axis inductor; the direct axis inductor includes: a direct-axis static inductor and a direct-axis dynamic inductor; the quadrature axis inductance includes: quadrature static inductance and quadrature dynamic inductance.

Optionally, the set pulse voltage includes: a series of pulse voltages and groups of pulse voltages; the determining unit applies the set pulse voltage to the motor and determines the inductance parameter of the motor, and the determining unit comprises the following steps: applying a series of pulse voltages to the motor to determine the initial position of a rotor of the motor; enabling the position of the rotor to be 0 degree, applying a pulse voltage group to the direct axis, and determining the direct axis inductance; enabling the rotor position to be 90 degrees, applying a pulse voltage group to a quadrature axis, and determining quadrature axis inductance; the rotor positions were taken at angles other than 0 and 90 degrees, and groups of pulsed voltages were applied to determine the cross-coupled inductance.

Optionally, wherein the determining unit applies a series of pulse voltages to the motor to determine an initial position of a rotor of the motor, comprises: sequentially increasing a pulse voltage application mode of a set electrical angle according to the voltage vector angle each time, applying a series of pulse voltages to the motor, and recording the current peak value and the corresponding angle after the pulse voltage is applied each time; under the angle corresponding to the maximum current value in all the recorded current peak values, continuously applying pulse voltage and gradually increasing the voltage amplitude of the pulse voltage until the current peak value reaches a preset value and then closing the pulse voltage; repeating the operation and continuing for a set time, and taking the angle corresponding to the maximum current value as the initial position of the rotor of the motor; and/or, the pulse voltage group comprises: four pulses in positive and negative directions; each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector magnitude and duration of control voltage and is realized by duty ratio signals of bridge arms of a rectification and inversion circuit for controlling a motor; the second part of pulse is to control the disappearance speed of the current and is realized by blocking a bridge arm of an inverter circuit of the control motor.

Optionally, wherein the determining unit applies the pulse voltage group to the direct axis to determine the direct axis inductance, includes: after a first group of pulse voltages are applied to the direct axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of direct axis inductance according to the magnetic flux; sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain direct-axis inductors under different current levels; and/or the determining unit applies a pulse voltage group to the quadrature axis to determine the quadrature axis inductance, and comprises: after a first group of pulse voltages are applied to the quadrature axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of quadrature axis inductance according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the quadrature axis inductance under different current levels.

Optionally, the determining unit determines a magnetic flux of the motor, including: calculating the magnetic flux of the motor according to the following formula:

Optionally, the determining unit determines a first set of direct axis inductances from the magnetic flux, including: determining a direct-axis static inductance and determining a direct-axis dynamic inductance; the determining unit determines a first set of quadrature axis inductances from the magnetic flux, including: determining quadrature axis static inductance and determining quadrature axis dynamic inductance; wherein, the determining unit determines the static inductance in determining the direct-axis static inductance and/or determining the quadrature-axis static inductance, and the determining unit comprises: calculating the corresponding static inductance according to the following formula:

the method comprises the following steps that A, a position angle of a motor rotor is theta, and i is the motor current under the current motor rotor angle;

and/or the determining unit determines the dynamic inductance in the direct-axis dynamic inductance and the quadrature-axis dynamic inductance, and the determining unit comprises the following steps: fitting a relation curve of the inductance and the current according to the direct axis inductance under the different current levels and the quadrature axis inductance under the different current levels, and calculating to obtain the dynamic inductance by combining the following formula:

wherein i_dIs the direct axis current of the motor i_qIs motor quadrature axis current, L'_d(i_d) Is the current direct-axis dynamic inductance, L, of the motor_d(id) is the current direct-shaft static inductance, L 'of the machine'_q(i_q) Is the current quadrature axis dynamic inductance, L, of the motor_q(i_q) The static inductance of the current direct axis of the motor is shown as d, the subscript of the direct axis of the motor is shown as q, the subscript of the quadrature axis of the motor is shown as k, the power number of the inductive current fitting polynomial is shown as k, and a is the coefficient of the inductive current fitting polynomial.

Optionally, the motor parameter further includes: a stator resistance of the motor; the motor parameter determination device further comprises: applying pulse voltage in the direction of a straight shaft of the motor until the current after the pulse voltage is applied reaches a set degree, and recording the current; applying a zero voltage vector to attenuate the current to obtain an integral value of the current with respect to time; and calculating the stator resistance of the motor according to the following formula by combining the inductance parameter of the motor:

wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

Optionally, the method further comprises: the acquisition unit is used for acquiring the running current of the motor under the condition that the motor runs; the determining unit is further configured to determine a target control parameter of the motor in advance according to the operating current based on the determined motor parameter, so as to control an operating process of the motor according to the target control parameter.

In accordance with another aspect of the present invention, there is provided an air conditioning system including: the motor parameter determination apparatus described above.

In accordance with the above method, a further aspect of the present invention provides a storage medium, which includes a stored program, wherein when the program runs, the apparatus in which the storage medium is located is controlled to execute the above motor parameter determination method.

In line with the above method, a further aspect of the present invention provides a processor for running a program, wherein the program is run to perform the above motor parameter determination method.

Therefore, according to the scheme of the invention, a series of voltage pulses are applied under the condition that the motor is static, so that the inductance parameter of the motor is determined; and then, the actual sizes of the direct-axis and quadrature-axis magnetic chains are calculated by utilizing the inductance parameters, so that the motor parameters of the motor are calculated by utilizing the sizes of the magnetic chains, the problem of low accuracy of identifying the motor parameters by utilizing a rational model of the motor is solved, and the effect of improving the accuracy of determining the motor parameters is achieved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

Fig. 1 is a schematic flowchart of an embodiment of determining an inductance parameter of a motor in the motor parameter determination method according to the present invention;

FIG. 2 is a schematic flow chart illustrating one embodiment of determining an initial position of a rotor of the electric machine in the method of the present invention;

FIG. 3 is a schematic flow chart illustrating one embodiment of determining the stator resistance of the motor in the method of the present invention;

FIG. 4 is a schematic flow chart illustrating one embodiment of a method of the present invention for controlling a motor based on determined motor parameters;

fig. 5 is a schematic structural diagram of an embodiment of the motor parameter determination apparatus of the present invention;

FIG. 6 is a schematic diagram of a PMSM parameter determination process for an embodiment of an electric machine (e.g., a PMSM) of the present invention;

FIG. 7 is a schematic view of a PMSM control circuit topology for an embodiment of an electric machine (e.g., a PMSM) of the present invention;

fig. 8 is a schematic diagram of a magnetic circuit hysteresis loop of a motor (e.g., a permanent magnet synchronous motor) according to an embodiment of the present invention;

FIG. 9 is a graph illustrating a voltage pulse time minimization unit of an embodiment of an electric machine (e.g., a permanent magnet synchronous machine) of the present invention;

FIG. 10 is a complete pulse set for one embodiment of an electric machine (e.g., a permanent magnet synchronous machine) of the present invention;

FIG. 11 is a schematic diagram illustrating a process of identifying static inductance of DC/AC shaft of an embodiment of a motor (e.g., a PMSM) according to the present invention;

FIG. 12 is a schematic view of rotor position identification for one embodiment of an electric machine (e.g., a permanent magnet synchronous machine) of the present invention;

FIG. 13 is a schematic diagram of a stator resistance identification waveform for an embodiment of an electric machine (e.g., a PMSM) of the present invention;

FIG. 14 is a schematic diagram illustrating a stator resistance identification process for an embodiment of an electric machine (e.g., a PMSM) of the present invention;

fig. 15 is a schematic diagram of an inductance-fitting curve of an embodiment of an electric machine (e.g., a permanent magnet synchronous machine) of the present invention, wherein (a) is a schematic diagram of a d-axis inductance-fitting curve and (b) is a schematic diagram of a q-axis inductance-fitting curve;

fig. 16 is a schematic diagram of a calculation flow of an inductance array of a motor (e.g., a permanent magnet synchronous motor) according to an embodiment of the present invention.

The reference numbers in the embodiments of the present invention are as follows, in combination with the accompanying drawings:

102-an obtaining unit; 104 — a determination unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an embodiment of the present invention, a method of determining a parameter of a motor is provided. The method can be applied to the permanent magnet synchronous motor. The permanent magnet synchronous motor can be applied to air conditioners, washing machines, refrigerators and the like, and can also be used for an inverter. The motor parameter determining method includes the following steps: inductance parameters of the motor. In the case where the motor parameter may include an inductance parameter of the motor, the method for determining the inductance parameter of the motor may include: and under the condition that the motor is static, applying a set pulse voltage to the motor, and determining inductance parameters of the motor so as to obtain the corresponding relation between the inductance and the current according to the inductance parameters under different currents. The characteristics of the applied voltage pulses can be seen in the following exemplary description.

In the set pulse voltage, the voltage amplitude is greater than or equal to the set amplitude, and the action time length is less than or equal to the set time length. The motor parameters may include: inductance parameters of the motor. The inductance parameter may include: direct axis inductance and quadrature axis inductance. The direct axis inductor may include: a direct axis static inductor and a direct axis dynamic inductor. The quadrature axis inductor may include: quadrature static inductance and quadrature dynamic inductance.

For example: the permanent magnet synchronous motor voltage pulse applying mode can obtain a voltage integral calculation result with higher precision by increasing the injection voltage amplitude and reducing the action time and greatly reducing the proportion of dead zone voltage drop, tube voltage drop and the like of an inverter in actual output voltage, thereby calculating motor inductance parameters (such as motor direct axis static inductance, direct axis dynamic inductance, quadrature axis static inductance, dynamic inductance and the like) with higher precision and avoiding the influence of the applied pulse on the position of a rotor. Namely, the method for identifying the voltage pulse of the permanent magnet synchronous motor is adopted, so that the influence of the pulse on the position of the motor rotor is effectively avoided.

Therefore, pulse voltage signals which are more than a set amplitude value and less than a set duration are applied to the motor under the condition that the motor is static, the actual magnetic flux of the motor can be calculated, the set motor model is combined, the inductance parameters of the motor can be accurately and reliably calculated, and the accuracy of determining the motor parameters, particularly the inductance parameters of the motor, can be improved.

In an alternative example, the set pulse voltage may include: a series of pulse voltages and groups of pulse voltages. The specific process of applying the set pulse voltage to the motor to determine the inductance parameter of the motor in the case that the motor is stationary can be seen in the following exemplary description.

In the scheme of the invention, the pulse for cutting off the current is used for blocking PWM, and the speed is high. This has the advantage that the influence of the pulse process on the motor position during the test is minimized.

In the following, with reference to the schematic flow chart of an embodiment of determining the inductance parameter of the motor in the method of the present invention shown in fig. 1, a specific process for determining the inductance parameter of the motor is further defined, which may include: step S110 to step S140.

And step S110, under the condition that the motor is static, applying a series of pulse voltages to the motor and determining the initial position of the rotor of the motor.

For example: the position of the rotor of the permanent magnet synchronous motor is obtained by applying pulse voltage, and the positions of the direct axis and the quadrature axis of the motor can be found only by the angle of the position of the rotor of the permanent magnet synchronous motor, so that a foundation is laid for applying direct axis and quadrature axis pulses in the subsequent treatment process.

Alternatively, the specific process of applying a series of pulse voltages to the motor to determine the initial position of the rotor of the motor in the case that the motor is stationary in step S110 may be as follows.

The following further describes a specific process of determining the initial position of the rotor of the motor in step S110, with reference to a flowchart of an embodiment of determining the initial position of the rotor of the motor in the method of the present invention shown in fig. 2, where the specific process may include: step S210 and step S220.

Step S210, under the condition that the motor is static, a series of pulse voltages are applied to the motor in a pulse voltage application mode of sequentially increasing the set electrical angle according to the voltage vector angle each time, and the current peak value and the corresponding angle after the pulse voltage is applied each time are recorded. When all the pulse voltages are applied, the electrical angles of all the pulse voltages need to cover the electrical angle of a set period.

And step S220, under the angle corresponding to the maximum current value in all the recorded current peak values, continuously applying the pulse voltage and gradually increasing the voltage amplitude of the pulse voltage until the current peak value reaches a preset value and then closing the pulse voltage. After repeating the operation and continuing for a set time, the angle corresponding to the obtained maximum current value is used as the initial position of the rotor of the motor.

For example: taking 6 times of pulse voltage application as an example, the voltage vector angle of each time is sequentially increased (such as 0 degree, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees), and all pulses are applied to cover exactly 360 degrees of electrical angle. The peak current value and the corresponding angle after each voltage pulse application are recorded. Comparing the magnitudes of these currents, the angle theta corresponding to the maximum current value₀Is the rotor positionThe most recent angle of inner. Then, pulses are applied at this angle and the pulse amplitude is increased step by step until the current reaches a preset value, at which point the pulses are turned off. This operation is then repeated, such that the cycle lasts approximately 1-2 seconds, and it is assumed that the zero position of the rotor of the machine has been identified as the current initial rotor position θ₀And the subsequent identification is carried out coordinate conversion under the angle.

Therefore, the initial position of the rotor is determined by sequentially increasing the pulse voltage application mode of the set electrical angle by the voltage vector angle each time under the condition that the motor is static, so that the initial position of the rotor can be determined more accurately and quickly.

And step S120, under the determined initial position of the rotor, enabling the position of the rotor to be 0 degree, applying a pulse voltage group to the straight shaft, and determining the inductance of the straight shaft.

More optionally, the applying the pulse voltage group to the direct axis to determine the direct axis inductance in step S120 may include: after a first group of pulse voltages are applied to the direct axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of direct axis inductance according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the direct-axis inductance under different current levels. For example: and identifying the direct axis inductance, specifically applying a pulse voltage group on the direct axis, recording the current, and solving the size of the flux linkage to obtain a first group of direct axis inductance parameters. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the direct axis inductance parameter values of the motor under different current levels.

And step S130, under the determined initial position of the rotor, enabling the position of the rotor to be 90 degrees, applying a pulse voltage group to the quadrature axis, and determining the quadrature axis inductance.

For example: the motor parameters are determined under the condition that the motor is static, namely, the motor is off-line, so that the off-line parameter identification of the permanent magnet synchronous motor can be realized. If the identification of the magnetic circuit saturated quadrature axis inductance of the permanent magnet synchronous motor can be realized, and an inductance table is formed; when the dynamic inductance is accurate, the current in the control process is stable without oscillation, so that the high-frequency loss is reduced; when the static inductance is accurate, the decoupling coordinate required by the control is accurate, the torque control can realize accurate maximum torque current ratio (MTPA) control, and the motor efficiency can reach the optimum under the given condition.

More optionally, the applying the pulse voltage group to the quadrature axis in step S130 to determine the quadrature axis inductance may include: after a first group of pulse voltages are applied to the quadrature axis, recording the current after the first group of pulse voltages are applied, determining the magnetic flux of the motor, and determining a first group of quadrature axis inductance according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the quadrature axis inductance under different current levels. For example: and identifying the quadrature axis inductance. Specifically, the operation of step 13 may be repeated continuously under the quadrature axis to obtain quadrature axis inductance parameters of the motor under different current levels. For example: and applying a pulse voltage group to the quadrature axis, recording the current, and obtaining the size of the flux linkage so as to obtain a first group of quadrature axis inductance parameters. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the quadrature axis inductance parameter values of the motor under different current levels.

For example: when the motor is static, a series of voltage pulses are applied, the actual magnetic flux of the motor is calculated, and then the inductance is obtained by using a formula 1 and a formula 2, so that an inductance-current parameter curve can be obtained according to different currents, and the performance of the motor can be improved. The motor models corresponding to the formula 1 and the formula 2 are as follows:

wherein u is_dIs the motor direct axis voltage u_qIs motor quadrature axis voltage i_dIs the direct axis current of the motor i_qIs motor quadrature axis current, L'_d(i_d) Is the current direct-axis dynamic inductance, L, of the motor_d(i_d) Is the current direct-shaft static inductance of the motor, L'_q(i_q) Is the current quadrature axis dynamic inductance, L, of the motor_q(i_q) Is the current direct-axis static inductance of the motor, the inductances are all functions of current, omega is the electrical angular velocity, psi is the permanent magnet flux linkage, psi_dIs a d-axis flux linkage Ψ_qIs the q-axis flux linkage, d is the subscript indicating the motor direct axis, and r is the motor resistance.

Therefore, when the motor is static, a series of voltage pulses are applied, the actual magnetic flux of the motor is calculated, and then the inductance is obtained by using the set motor model, so that an inductance-current parameter curve can be obtained according to different currents, the motor is controlled according to the inductance-current parameter curve, and the performance of the motor can be improved.

In step S140, the rotor position takes other angles than 0 degree and 90 degrees, and the pulse voltage group is applied to determine the cross-coupling inductance.

Therefore, under the condition that the motor is static, a series of pulse voltages are applied to the motor to determine the initial position of the rotor, and then pulse voltage groups are respectively applied to the direct axis and the quadrature axis to determine the direct axis inductance and the quadrature axis inductance, so that the inductance parameters of the motor can be obtained quickly and accurately.

Alternatively, the pulse voltage groups in step S120, step S130 and step S140 may include: four pulses in both positive and negative directions. Each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector size and duration of control voltage and is realized by duty ratio signals of bridge arms of a rectification and inversion circuit for controlling the motor; the second part of pulse is to control the disappearance speed of the current, and is realized by blocking a bridge arm of an inverter circuit of the control motor, which is equivalent to applying the maximum voltage vector which can be provided by the inverter circuit at present, and forcing the current to return to zero rapidly.

For example: the pulse voltage group is formed by a group of voltage pulses, belongs to the most basic unit, and the combination form can be changed, but can not be separated for independent use. The reason for this is that a total of 4 pulses in the positive and negative directions can be used to offset the total angular displacement, ensuring that the rotor position of the motor can be displaced to zero after the pulse application is finished. Referring to the examples shown in fig. 4 and 5, each small pulse process is composed of two parts, the first part of pulse is applied voltage and is completed by duty ratio signal action of 6 bridge arms. The magnitude and duration of the voltage vector are determined according to the response current, and the phenomenon that overcurrent appears in the operation process is avoided; the duration is typically one PWM cycle to 10 PWM cycles, which is sufficient for most motor applications. The second part of pulses are realized by blocking all 6 bridge arms, so that the current can be fully ensured to disappear quickly, and generally one to two PWM periods can be ended. Here, first, the pulse time is small enough relative to the motor time constant so that the motor speed response, the position response, is substantially zero. Secondly, the applied pulse voltage is large enough and far larger than the resistance voltage drop of the motor, the dead zone voltage drop of the inverter, the voltage drop of the switch tube and the like.

For example: the polarity of the four small pulses of the voltage pulse group can also be changed. If the polarity is changed, the four small pulses in the voltage pulse group can be negative pulses, positive pulses and negative pulses to form a group.

Therefore, the pulse voltage group of the minimum unit is formed by setting a plurality of pulses in the positive direction and the negative direction, the total angular displacement can be counteracted, and the position of the motor rotor can be enabled to be in zero displacement after the application of the pulses is finished.

Still further optionally, in the above example, the determining the magnetic flux of the motor may include: calculating the magnetic flux of the motor according to the following formula:

For example: the applied pulses are typically within 1-2ms, and in most cases the upper formula, although approximately equal, results in a substantially negligible error. Taking the dead zone voltage drop of 5V as an example, the voltage pulse value is 300V, the voltage error is about 5V/300V to 1.7%, and the precision is within 1.7%.

Therefore, the magnetic flux is calculated by using the approximate formula, the magnetic flux can be quickly obtained, the error is small, and the calculation precision can be ensured.

Still further optionally, in the above example, the determining a first set of direct-axis inductances from the magnetic flux may include: determining the static inductance of the direct axis and determining the dynamic inductance of the direct axis. The determining a first set of quadrature axis inductances from the magnetic flux may include: determining quadrature axis static inductance and determining quadrature axis dynamic inductance.

In a specific example, the determining the static inductance in the determining the direct-axis static inductance and/or determining the quadrature-axis static inductance may include: calculating the corresponding static inductance according to the following formula:

where θ is the position angle of the motor rotor, and i is the motor current at the current motor rotor angle.

Therefore, by calculating the static inductance by using the magnetic flux and the current, the static inductance can be determined quickly, and the accuracy can be ensured.

In a specific example, the determining the dynamic inductance in determining the direct-axis dynamic inductance and determining the quadrature-axis dynamic inductance may include: fitting a relation curve of the inductance and the current according to the direct axis inductance under the different current levels and the quadrature axis inductance under the different current levels, and calculating to obtain the dynamic inductance by combining the following formula:

For example: the dynamic inductance may be specifically obtained by fitting an inductance-current curve according to the obtained direct axis inductance parameter values of the motor at different current levels and the obtained quadrature axis inductance parameter values of the motor at different current levels, and obtaining a dynamic inductance-current fitting curve according to formula 2. And finally, obtaining the direct axis/quadrature axis static inductance and the dynamic inductance under different current levels according to the obtained curve (namely the dynamic inductance-current fitting curve).

The following table can be obtained from the measurement records:

direct axis current	i_d1	i_d2	…	i_dn
					Straight shaft inductor	L_d1	L_d2	…	L_dn
Quadrature axis current	i_q1	I_q2	…	i_qn
					Quadrature axis inductor	L_q1	L_q2	…	L_qn

Fitting the L (i) curve to the curve,

the inductance expression can be obtained:

obtaining a dynamic inductance relational expression according to the static dynamic inductance relational expression, and respectively obtaining direct-axis dynamic inductances and quadrature-axis dynamic inductances:

wherein k is the power degree of the inductor current fitting polynomial, and a is the coefficient of the inductor current fitting polynomial.

Therefore, the relation curve of the inductance and the current is fitted according to the direct-axis inductance under different current levels and the quadrature-axis inductance under different current levels, and the dynamic inductance is obtained by combining the motor model calculation, so that the dynamic inductance of the motor can be quickly and accurately obtained.

In an optional embodiment, the motor parameters may further include: a stator resistance of the motor; the method for determining the motor parameter, that is, in the case that the motor parameter may further include a stator resistance of the motor, may further include: a process of determining a stator resistance of an electric machine.

In the following, with reference to the schematic flow chart of an embodiment of determining the stator resistance of the motor in the method of the present invention shown in fig. 3, a specific process for determining the stator resistance of the motor is further defined, which may include: step S310 to step S330.

In step S310, a pulse voltage is applied in the direction of the motor shaft until the current after the pulse voltage is applied reaches a predetermined level, and the current is recorded.

In step S320, a zero voltage vector is applied to attenuate the current, so as to obtain the integral value of the current with respect to time.

Step S330, combining the inductance parameter of the motor, calculating the stator resistance of the motor according to the following formula:

wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

For example: the method of voltage integration can be used for calculating the actual direct-axis and quadrature-axis flux linkage sizes, and further calculating motor parameters of the motor, and the method can include the following steps: the motor direct-axis static inductance, the direct-axis dynamic inductance, the quadrature-axis static inductance, the dynamic inductance, the stator winding resistance and the like. Such as: the stator winding resistance can be calculated by adopting a current integration method, on the basis of the flux linkage, zero-voltage vector motor current attenuation is applied, current integration is carried out in the whole current attenuation process by means of Lenz law, and finally the winding resistance is obtained, so that the winding resistance can be quickly and accurately obtained.

For example: the stator resistance of the motor is identified, see for example the example shown in fig. 8. In order to ensure that the motor rotor does not rotate in the identification process, pulse voltage is applied in the direction of the straight shaft of the motor until the current value reaches a considerable value, and the value I is recorded_r. Then, a zero voltage vector is applied to start the current decay, and at this time, the integral value S of the current with respect to time is obtained_r. Finally, the resistance r of the motor can be obtained according to the following resistance calculation formula:

the zero-voltage vector is realized by short circuit, specifically, 3 upper bridge arms are all switched on and 3 lower bridge arms are blocked, or 3 lower bridge arms are all switched on and 3 upper bridge arms are all blocked. The zero vector of the conventional complementary mode PWM output fails the resistance discrimination due to the dead band voltage drop. In the scheme of the invention, the zero voltage applying mode is adopted, so that the failure of resistance identification caused by dead zone voltage drop can be avoided.

For example: adopting the magnetic linkage to calculate the resistance, calculating the magnetic linkage size when giving the current through the static inductance that is discerned, then applying the zero voltage vector, obtaining the resistance size through the integral calculation:

according to a voltage equation, calculating the resistance r of the motor:

wherein the content of the first and second substances,

is d-axis flux linkage variation, L_d(i) The inductance value is the inductance value when the direct-axis current is i, i is the direct-axis current value immediately before the zero vector is applied, and the integral of the denominator is the integral of the direct-axis current in the attenuation process under the zero voltage vector.

Therefore, pulse voltage signals above a set amplitude value and below a set time length are applied to the motor under the condition that the motor is static, inductance parameters, flux linkage and motor parameters of the motor are determined in sequence, and accuracy of determining the motor parameters can be guaranteed.

In an alternative embodiment, the method may further include: a process of controlling the motor based on the determined motor parameter.

In the following, with reference to a schematic flow chart of an embodiment of the method of the present invention shown in fig. 4, which is used for controlling a motor based on a determined motor parameter, a specific process of controlling the motor based on the determined motor parameter is further described, and may include: step S410 and step S420.

And step S410, acquiring the running current of the motor under the condition that the motor runs.

And step S420, predetermining target control parameters of the motor according to the running current based on the determined motor parameters, so as to control the running process of the motor according to the target control parameters.

For example: static inductance parameters and dynamic inductance parameters under the condition of different current values are obtained, and in the running process of the motor, different inductance parameters can be selected according to the actual current of the motor to control the motor. If the motor parameters obtained by identification are utilized, the required control parameters can be calculated in advance according to the running current, the controller can meet the control requirement of the compressor without needing a great amount of manual debugging parameters of designers, and the universality of the air conditioner compressor controller is greatly enhanced.

Therefore, the control performance of the motor can be improved by determining the control parameters of the motor according to the running current and the motor parameters of the motor.

Through a large number of tests, the technical scheme of the embodiment is adopted, and the motor parameters are identified under the static condition of the motor, so that the off-line parameter identification of the permanent magnet synchronous motor can be realized, the parameters of the motor can be accurately identified, and the control performance can be improved.

According to the embodiment of the invention, a motor parameter determination device corresponding to the motor parameter determination method is also provided. Referring to fig. 5, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The motor parameter determining device may include: inductance parameters of the motor. The motor parameter determination device, that is, in a case where the motor parameter may include an inductance parameter of the motor, the determination device of the inductance parameter of the motor may include: a determination unit 104.

In an example, the determining unit 104 may be configured to apply a set pulse voltage to the motor when the motor is stationary, and determine an inductance parameter of the motor, so as to obtain a corresponding relationship between inductance and current according to the inductance parameter at different currents.

For example: the permanent magnet synchronous motor voltage pulse applying mode can obtain a voltage integral calculation result with higher precision by increasing the injection voltage amplitude and reducing the action time and greatly reducing the proportion of dead zone voltage drop, tube voltage drop and the like of an inverter in actual output voltage, thereby calculating motor inductance parameters (such as motor direct axis static inductance, direct axis dynamic inductance, quadrature axis static inductance, dynamic inductance and the like) with higher precision and avoiding the influence of the applied pulse on the position of a rotor. That is to say, adopt PMSM voltage pulse's recognition device, effectively avoided the influence of pulse to motor rotor position.

In an alternative example, the set pulse voltage may include: a series of pulse voltages and groups of pulse voltages. The determining unit 104 may apply a set pulse voltage to the motor to determine an inductance parameter of the motor when the motor is stationary, and may include:

the determining unit 104 may be further configured to apply a series of pulse voltages to the motor to determine an initial position of the rotor of the motor when the motor is stationary. The specific function and processing of the determination unit 104 are referred to in step S110.

Alternatively, the determining unit 104 applies a series of pulse voltages to the motor to determine the initial position of the rotor of the motor when the motor is at rest, and may include:

the determining unit 104 may be further configured to apply a series of pulse voltages to the motor in a pulse voltage applying manner that the voltage vector angle increases by a set electrical angle each time when the motor is stationary, and record a current peak value and a corresponding angle after the pulse voltage is applied each time. When all the pulse voltages are applied, the electrical angles of all the pulse voltages need to cover the electrical angle of a set period. The specific function and processing of the determination unit 104 are also referred to in step S210.

The determining unit 104 may be further configured to continue to apply the pulse voltage and gradually increase the voltage amplitude of the pulse voltage at an angle corresponding to the maximum current value among all the recorded current peak values until the pulse voltage is turned off after the current peak value reaches the preset value. After repeating the operation and continuing for a set time, the angle corresponding to the obtained maximum current value is used as the initial position of the rotor of the motor. The specific function and processing of the determination unit 104 are also referred to in step S220.

For example: taking 6 times of pulse voltage application as an example, the voltage vector angle of each time is sequentially increased (such as 0 degree, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees), and all pulses are applied to cover exactly 360 degrees of electrical angle. The peak current value and the corresponding angle after each voltage pulse application are recorded. Comparing the magnitudes of these currents, the angle theta corresponding to the maximum current value₀The closest angle in the rotor position. Then, pulses are applied at this angle and the pulse amplitude is increased step by step until the current reaches a preset value, at which point the pulses are turned off. This operation is then repeated, such that the cycle lasts approximately 1-2 seconds, and it is assumed that the zero position of the rotor of the machine has been identified as the current initial rotor position θ₀And the subsequent identification is carried out coordinate conversion under the angle.

The determining unit 104 may be further configured to, in the determined initial position of the rotor, set the rotor position to 0 degree, apply a pulse voltage group to the direct axis, and determine the direct axis inductance. The specific function and processing of the determination unit 104 are also referred to in step S120.

Optionally, the determining unit 104 applies the pulse voltage group to the direct axis to determine the direct axis inductance, and may include: the determining unit 104 may be further configured to record a current after the first group of pulse voltages are applied to the direct axis, determine a magnetic flux of the motor, and determine a first group of direct axis inductances according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the direct-axis inductance under different current levels. For example: and identifying the direct axis inductance, specifically applying a pulse voltage group on the direct axis, recording the current, and solving the size of the flux linkage to obtain a first group of direct axis inductance parameters. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the direct axis inductance parameter values of the motor under different current levels.

The determining unit 104 may be further configured to determine quadrature axis inductance by applying a pulse voltage group to a quadrature axis with the rotor position being 90 degrees at the determined initial rotor position. The specific function and processing of the determination unit 104 are also referred to in step S130.

Optionally, the determining unit 104 applies the pulse voltage group to the quadrature axis to determine the quadrature axis inductance, and may include: the determining unit 104 may be further configured to record a current after the first group of pulse voltages are applied to the quadrature axis, determine a magnetic flux of the motor, and determine a first group of quadrature axis inductances according to the magnetic flux; and sequentially circulating and gradually increasing the voltage amplitude of the pulse voltage group to enable the current to reach the maximum current allowed by the motor so as to obtain the quadrature axis inductance under different current levels. For example: and identifying the quadrature axis inductance. Specifically, the operation of step 13 may be repeated continuously under the quadrature axis to obtain quadrature axis inductance parameters of the motor under different current levels. For example: and applying a pulse voltage group to the quadrature axis, recording the current, and obtaining the size of the flux linkage so as to obtain a first group of quadrature axis inductance parameters. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the quadrature axis inductance parameter values of the motor under different current levels.

The determining unit 104 may be further configured to apply the pulse voltage group to determine the cross-coupling inductance when the rotor position takes other angles than 0 degree and 90 degrees. The specific function and processing of the determination unit 104 are also referred to in step S140.

Optionally, in the above example, the set of pulse voltages may include: four pulses in both positive and negative directions. Each pulse specifically comprises two parts of pulses, wherein the first part of pulses is the vector size and duration of control voltage and is realized by duty ratio signals of bridge arms of a rectification and inversion circuit for controlling the motor; the second part of pulse is to control the disappearance speed of the current and is realized by blocking a bridge arm of an inverter circuit of the control motor.

In a further alternative example, the determining unit 104 in the above example may determine the magnetic flux of the motor, and may include: the determining unit 104 may be further configured to calculate the magnetic flux of the motor according to the following formula:

Therefore, the magnetic flux is calculated by using the approximate formula, the magnetic flux can be quickly obtained, the error is small, and the calculation precision can be ensured.

In a further alternative example, the determining unit 104 in the above example determines the first set of direct-axis inductances according to the magnetic fluxes, and may include: determining the static inductance of the direct axis and determining the dynamic inductance of the direct axis. The determining unit 104 determines a first set of quadrature axis inductances from the magnetic fluxes, and may include: determining quadrature axis static inductance and determining quadrature axis dynamic inductance.

In a specific example, the determining unit 104 determines the static inductance in the direct-axis static inductance and/or the quadrature-axis static inductance, and the determining may include: the determining unit 104 may be further configured to calculate the corresponding static inductance according to the following formula:

where θ is the position angle of the motor rotor, and i is the motor current at the current motor rotor angle.

Therefore, by calculating the static inductance by using the magnetic flux and the current, the static inductance can be determined quickly, and the accuracy can be ensured.

In a specific example, the determining unit 104 determines the dynamic inductance of the direct axis dynamic inductance and the quadrature axis dynamic inductance, and the determining may include: the determining unit 104 may be further configured to fit a relationship curve between the inductance and the current according to the direct axis inductance at different current levels and the quadrature axis inductance at different current levels, and calculate to obtain the dynamic inductance by combining the following formula:

The following table can be obtained from the measurement records:

direct axis current	i_d1	i_d2	…	i_dn
					Straight shaft inductor	L_d1	L_d2	…	L_dn
Quadrature axis current	i_q1	I_q2	…	i_qn
					Quadrature axis inductor	L_q1	L_q2	…	L_qn

Fitting the L (i) curve to the curve,

the inductance expression can be obtained:

wherein k is the power degree of the inductor current fitting polynomial, and a is the coefficient of the inductor current fitting polynomial.

In an optional embodiment, the motor parameters may further include: stator resistance of the motor. The motor parameter determination device, that is, in a case that the motor parameter may further include a stator resistance of the motor, the determination device of the stator resistance of the motor may further include:

the determining unit 104 may be further configured to apply a pulse voltage in a direction of a direct axis of the motor, and record the current after the pulse voltage is applied until the current reaches a set level. The specific function and processing of the determination unit 104 are also referred to in step S310.

The determination unit 104 may be further configured to apply a zero voltage vector to attenuate the current to obtain an integrated value of the current with respect to time. The specific function and processing of the determination unit 104 are also referred to in step S320.

The determining unit 104 may be further configured to calculate, in combination with the inductance parameter of the motor, a stator resistance of the motor according to the following formula: the specific function and processing of the determination unit 104 are also referred to in step S330.

Wherein r is the stator resistance of the motor, I_rFor recorded current, S_rIs the integral value of current over time, L_d(i_d) Is the current direct-axis static inductance of the motor.

For example: the device that can utilize voltage integral calculates actual direct axis, quadrature axis magnetic linkage size, and then calculates the motor parameter of motor, can include: the motor direct-axis static inductance, the direct-axis dynamic inductance, the quadrature-axis static inductance, the dynamic inductance, the stator winding resistance and the like. Such as: the stator winding resistance is calculated, a current integration device can be adopted, on the basis of the size of the magnetic flux linkage, zero-voltage vector motor current attenuation is applied, then current integration is carried out in the whole current attenuation process by means of Lenz law, the size of the winding resistance is obtained finally, and the winding resistance can be obtained quickly and accurately.

according to a voltage equation, calculating the resistance r of the motor:

wherein the content of the first and second substances,is d-axis flux linkage variation, L_d(i) The inductance value is the inductance value when the direct-axis current is i, i is the direct-axis current value immediately before the zero vector is applied, and the integral of the denominator is the integral of the direct-axis current in the attenuation process under the zero voltage vector.

In an alternative embodiment, the method may further include: a process of controlling the motor based on the determined motor parameter.

The obtaining unit 102102 may be configured to obtain an operating current of the motor when the motor is in operation. The specific function and processing of the determination unit 104 are also referred to in step S410.

The determining unit 104 may be further configured to determine a target control parameter of the motor in advance according to the operating current based on the determined motor parameter, so as to control an operating process of the motor according to the target control parameter. The specific function and processing of the determination unit 104 are also referred to step S420.

Therefore, the control performance of the motor can be improved by determining the control parameters of the motor according to the running current and the motor parameters of the motor.

Since the processes and functions implemented by the apparatus of this embodiment substantially correspond to the embodiments, principles and examples of the method shown in fig. 1 to 4, the description of this embodiment is not detailed, and reference may be made to the related descriptions in the foregoing embodiments, which are not repeated herein.

Through a large number of tests, the technical scheme of the invention is adopted, and the off-line identification of the dynamic inductance of the permanent magnet synchronous motor is realized by acquiring the dynamic inductance off line, so that the control efficiency, the stability and other performances of the motor can be changed along with the slight change of the motor parameters, and the optimal control is achieved.

According to the embodiment of the invention, an air conditioning system corresponding to the motor parameter determination device is also provided. The air conditioning system may include: the motor parameter determination apparatus described above.

In order to obtain a high-performance control effect, during the operation of the permanent magnet synchronous motor, motor parameters such as the position of a rotor need to be detected. However, in some specific occasions, such as special occasions like high-temperature sealing, dust environment, etc., especially in cost-sensitive use scenes like air conditioning systems, it is often impractical to use a position sensor, and control is generally realized by using an algorithm without a position sensor. However, the control of a position sensorless permanent magnet synchronous machine is based on a mathematical model of the machine, which in turn depends on the parameters of the permanent magnet synchronous machine. In general, the inaccurate parameters of the permanent magnet synchronous motor affect the running condition of the motor, cause the problem of noise increase and the like, but generally do not stop. However, in the position sensorless control, the parameters of the permanent magnet synchronous motor represent the performance of the position sensor to a certain extent, so that the inaccuracy of the parameters in this case also causes the motor efficiency to be greatly reduced, the maximum torque to current ratio (MTPA) effect is lost, the control is unstable, the control fails in a light case, and the motor is demagnetized and permanently damaged in a heavy case.

For the air conditioning system, a position sensor is used, the cost is increased on one hand, more importantly, the inside of a compressor in the air conditioner is in a high-temperature and high-pressure environment, the number of the sensors which can be used is very small, and the installation is also very difficult. Even if the installation is successful, the failure rate is very high and therefore sensors are not generally employed.

The model depends on the parameters of the permanent magnet synchronous motor, and the position sensor can directly acquire the position of the rotor, so that the related calculation of the control of the motor is completed. If the motor parameters are not correct, the calculated position is naturally wrong, and the control effect is greatly reduced. In short, this solution only works if the motor parameters are correct.

In some technologies, motor parameters are generally provided by manufacturer specifications, and the effect can be achieved through debugging. The existing motor parameter determination methods mostly consider the ideal model of the motor, have certain difference with the reality, and have limited recognition effect. In practice, as the service time of the permanent magnet synchronous motor increases, the motor parameters can have irreversible changes, and in addition, the magnetic saturation phenomenon is also very obvious. If the control effect is not adjusted according to the specification of a manufacturer, the control effect is reduced along with the change of the motor. On the other hand, the effective parameter identification can expand the universality of the motor driver, and particularly reduces the manpower debugging cost and the after-sale service efficiency of products. Firstly, the given parameters may be larger or smaller under the actual operating current condition, and the efficiency of the motor is mainly influenced at the moment, which is reflected on a high-power motor that the current level is increased, a thicker connecting wire is needed between the motor and the inverter, a power module with larger rated current and the like, and the hardware cost of the controller is greatly increased. Second, if the parameters are too far apart, the controller may be rendered completely inoperable.

In an alternative embodiment, the invention provides a more accurate motor parameter determination method, in particular a permanent magnet synchronous motor parameter identification method.

In an optional example, the scheme of the invention can realize the self-tuning of the control parameters of the permanent magnet synchronous motor. On one hand, a PI regulator for controlling the motor current needs motor parameters to be set. On the other hand, the estimation of the rotor position used in the FOC control of the compressor also requires the use of motor parameters.

Specifically, the calculating of the actual direct-axis and quadrature-axis flux linkage by using a voltage integration method to further calculate the motor parameter of the motor may include: the direct-axis static inductance, the direct-axis dynamic inductance, the quadrature-axis static inductance, the quadrature-axis dynamic inductance, the stator winding resistance and the like of the motor. When a voltage integration method is adopted, the conventional method generally has small given voltage, the inverter has serious nonlinear influence, and the calculation result has errors.

The conventional method is an ohm law calculation method, and requires current and voltage drop of a resistor. In a common method, a direct current voltage is directly applied to obtain a direct current, and then the voltage is divided by the current to obtain a resistor, or a current closed loop is utilized to apply a certain current value, and then the division is performed to obtain the resistor. In the former method, the voltage is relatively stable and the noise is low, and in the latter method, the current is relatively stable and the noise is low, but at least one quantity is relatively noisy. Secondly, the resistance of the motor is generally small, the actual voltage drop is also very small, and the motor is very difficult to extract. More often, the voltage drop caused by the non-linearity of the inverter is already larger than the resistance voltage drop, and the two are difficult to separate. According to the scheme of the invention, ohm's law calculation is not directly adopted, but the electromagnetic induction law is utilized, the flux linkage and the integral value of current with respect to time are utilized for calculation, firstly, the variables participating in calculation have no noise interference, and secondly, as a zero voltage vector is applied, the problem of non-linearity of the inverter does not exist, and the error caused by voltage interference is eliminated.

The scheme of the invention provides a voltage pulse applying mode of the permanent magnet synchronous motor, and the proportion of dead zone voltage drop, tube voltage drop and the like of the inverter in actual output voltage can be greatly reduced by increasing the injection voltage amplitude and reducing the acting time, and a voltage integral calculation result with higher precision can be obtained, so that motor inductance parameters (such as motor direct axis static inductance, direct axis dynamic inductance, quadrature axis static inductance, quadrature axis dynamic inductance and the like) with higher precision can be calculated, and the influence of the applied pulse on the position of a rotor can be avoided. Namely, the method for identifying the voltage pulse of the permanent magnet synchronous motor is adopted, so that the influence of the pulse on the position of the motor rotor is effectively avoided.

In the scheme of the invention, a blocking pulse process is added in the pulse application mode. Firstly, it is required that the time for applying the pulse is short, so that the rotor position of the motor is moved, and the range of the rotation is very small, and secondly, the pulse is applied in such a way that the rotor position of the motor is still at the original position after the application of one group of pulses is finished. Therefore, the accuracy loss caused by the position problem is solved. And secondly, the invention does not require closed loop, thus avoiding the setting of preset PI control parameters and enhancing the universality. Finally, the invention has enough guarantee on the parameter identification precision. Common inverter non-linearity, voltage sampling accuracy, etc. limitations do not exist here.

In addition, the stator winding resistance can be calculated by adopting a current integration method, on the basis of the flux linkage, zero-voltage vector motor current attenuation is applied, current integration is carried out in the whole current attenuation process by means of Lenz law, and finally the winding resistance is obtained. The method uses an integral method, solves the defects that the conventional method is easily influenced by factors such as current sampling error, distortion of actually applied voltage, temperature rise of a winding caused by long-time current application, resistance change and the like, and obtains the technical effect of quickly and accurately obtaining the resistance of the winding.

The conventional method is to use ohm's law for calculation. As an example, the resistance of the stator of the compressor is 0.6 ohm, the demagnetization current of the compressor is 50A, and in order to identify the current applied to the resistor is 10A, the voltage drop of the resistor is 10 × 0.6V — 6V, the sampling precision of the current is high, and the general problem is not great. And the voltage sampling accuracy has been difficult to recognize for 1-2V. In addition, inverters also suffer from dead-time voltage drops, typically several to tens of volts. In this method, the effective resistance drop is comparable to the dead zone drop, and it is extremely difficult to identify the true resistance drop. The scheme of this patent adopts the current to the integral of time, utilizes lenz's law to calculate, and the parameter that involves is current sampling, and the calculation of magnetic linkage does not have direct relation with voltage. The problem of voltage accuracy can be considered to be avoided by the scheme provided by the patent.

In an optional example, the scheme of the present invention provides an offline parameter identification method for a permanent magnet synchronous motor, which can implement offline parameter identification for the permanent magnet synchronous motor. The control of some permanent magnet synchronous motor compressors adopts a sensorless scheme, and the control effect is influenced by the decisive influence of the parameters of the used motor.

Optionally, the dynamic inductance can be obtained offline, and offline identification of the dynamic inductance of the permanent magnet synchronous motor is realized, so that the control efficiency, stability and other performances of the motor can be changed along with slight changes of motor parameters to achieve the optimal performance. Preferably, the identification of the saturated quadrature axis inductance of the magnetic circuit of the permanent magnet synchronous motor can be realized, and an inductance table is formed.

When the dynamic inductance is accurate, the current in the control process is stable and does not vibrate, so that the high-frequency loss is reduced. When the static inductance is accurate, the decoupling coordinate required by the control is accurate, the torque control can realize accurate maximum torque current ratio (MTPA) control, and the motor efficiency can reach the optimum under the given condition.

Furthermore, according to the scheme of the invention, the identified motor parameters are utilized, the required control parameters can be calculated in advance according to the running current, the controller can meet the control requirement of the compressor without needing a great amount of manual debugging parameters of designers, and the universality of the controller of the air conditioner compressor is greatly enhanced.

In an alternative embodiment, reference may be made to the examples shown in fig. 6 to 16 to illustrate a specific implementation process of the scheme of the present invention.

The parameter identification of the permanent magnet synchronous motor already has a plurality of relevant parameters, but most technical schemes do not consider the magnetic circuit saturation characteristic of the motor (see the example shown in fig. 3), and the calculated motor parameters all belong to an ideal model of the motor, so that the effect is poor in practical use. The scheme of the invention fully considers the characteristic, and the used motor model is as follows:

Due to the saturation behaviour, the corresponding parameters can still be identified if the ideal model of the motor is still used. Taking inductance as an example, the identified parameter is either only the value of the dynamic inductance or only the value of the static inductance, although neither may be the case. For example, there is a testing method that, under the condition of motor stalling, voltages with different frequencies are applied, current response is tested, and inductance parameters are calculated. If no saturation property is intervened, the measured result is completely correct. However, once the saturation characteristic problem exists, the saturation depth is very considerable under the condition of large power such as a compressor, and the parameters measured by the method have little reference value. The compressor is difficult to operate first using such parameters. Even when operational, the efficiency can be very poor.

Based on the motor model, according to the scheme of the invention, when the motor is static, a series of voltage pulses are applied, the actual magnetic flux of the motor is calculated, and then the inductance is obtained by using the formula 1 and the formula 2, so that an inductance-current parameter curve can be obtained according to different currents, the previous fixed ideal motor parameters can be replaced, and the motor performance is improved. The relationship between voltage u, flux linkage psi, current i and resistance r can be as in equation 3:

the parameters are identified off line, the motors with different parameters can be identified firstly, and then the software control parameters are configured in a targeted manner, so that the purpose that one set of algorithm is suitable for the motors with different parameters can be achieved, and the effect of carrying out control optimization on the different motors can also be achieved. The terms magnetic flux and flux linkage are used herein in concert.

For the resistance parameter of the motor, the scheme of the invention is to calculate the resistance through the flux linkage on the basis of accurately obtaining the inductance parameter, thereby avoiding the problem caused by inaccurate voltage when directly using the ohm law.

In the scheme of the invention, firstly, the identification of the resistor is completely unrelated to the dead zone, and because a real zero voltage vector method is adopted during the identification of the resistor, the problem of dead zone influence does not exist at all. Secondly, because there is no switching signal action when the zero voltage vector is applied, the noise of the sampling process is very small. Finally, the current participates in the operation by the integral result of time, and has higher interference filtering effect. According to equation 3, the only possible error is the precise calculation of the flux linkage, which is guaranteed by the inductance identification part of this patent. In conclusion, the resistance identification scheme of the invention has higher precision.

Fig. 6 is a schematic diagram of a parameter determination process of a permanent magnet synchronous motor according to an embodiment of the present invention. As shown in fig. 6, the process for determining parameters of a permanent magnet synchronous motor may include:

and 11, identifying the position of the rotor. Specifically, pulse voltage can be applied to obtain the position of the rotor of the permanent magnet synchronous motor, and the positions of the direct axis and the quadrature axis of the motor can be found only by the angle of the position of the rotor of the permanent magnet synchronous motor, so that a foundation is laid for applying direct axis and quadrature axis pulses in the subsequent treatment process.

And step 12, taking the rotor position as 0 degree.

Specifically, referring to the example shown in fig. 12, the process of determining the initial position of the rotor may include: the pulse voltage applied to the motor several times, which may be the most common voltage pulse, i.e. 6 switching tubes in complementary mode, provides a non-zero voltage vector in a duty cycle manner, which needs to be distinguished in particular from the pulse application manner when identifying the inductance. In the scheme of the invention, for example, 6 times of pulse voltage application is taken as an example, the voltage vector angles of each time are sequentially increased (such as 0 degree, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees), and all pulses are applied to cover exactly 360 degrees of electrical angles. The peak current value and the corresponding angle after each voltage pulse application are recorded. Comparing the magnitudes of these currents, the angle theta corresponding to the maximum current value₀The closest angle in the rotor position. Then, pulses are applied at this angle and the pulse amplitude is increased step by step until the current reaches a preset value, at which point the pulses are turned off. This operation is then repeated, such that the cycle lasts approximately 1-2 seconds, and it is assumed that the zero position of the rotor of the machine has been identified as the current initial rotor position θ₀And the subsequent identification is carried out coordinate conversion under the angle.

For example: during a 360 degree week we apply 6 pulses. Since we do not know where the true initial position is, we have arbitrary decisions about 0 degrees, 60 degrees, etc. However, the true rotor home position corresponds to the maximum current response, so that by observing the current result response, it can be determined which of the previously determined 0 degrees, 60 degrees, etc. is actually closest to the zero position. In general (i.e. the motor is normal and the rotor is not locked and can not rotate), 3-5% of rated current is applied, and the zero position (initial position) of the motor is coincident with the position of the current vector. The rotor position is the value of the angle of the N pole of the motor rotor about the rotor center away from the axis of the a phase winding, i.e., the rotor position angle in fig. 12. Rotor position the abbreviation of rotor position angle, the value of which is an angle.

And step 13, identifying the direct axis inductance. Specifically, a pulse voltage group is applied to the direct axis, the current is recorded, the size of the flux linkage is obtained, and then a first group of direct axis inductance parameters is obtained. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the direct axis inductance parameter values of the motor under different current levels.

Optionally, the pulse voltage group is composed of a group of voltage pulses, belongs to the most basic unit, and the combination form can be changed, but can not be separated for independent use. The reason for this is that the total of 4 pulses in the positive and negative directions are used to offset the total angular displacement, and it is ensured that the position of the motor rotor can be displaced to zero after the pulse application is finished. Referring to the examples shown in fig. 9 and 10, each small pulse process is composed of two parts, the first part of pulses are applied voltages and are completed by duty ratio signals of 6 bridge arms; the magnitude and duration of the voltage vector are determined according to the response current, and the phenomenon that overcurrent appears in the operation process is avoided; the duration is typically one PWM cycle to 10 PWM cycles, which is sufficient for most motor applications. The second part of pulses are realized by blocking all 6 bridge arms, so that the current can be fully ensured to disappear quickly, and generally one to two PWM periods can be ended. Here, first, the pulse time is small enough relative to the motor time constant so that the motor speed response, the position response, is substantially zero. Secondly, the applied pulse voltage is large enough and far larger than the resistance voltage drop of the motor, the dead zone voltage drop of the inverter, the voltage drop of the switch tube and the like.

Flux linkage variation of winding, i.e. magnetic fluxCan be calculated byWritten approximately as:

where u is the magnitude of the applied voltage vector, i is the current of the motor, r is the resistance of the motor, u is the magnitude of the applied voltage vector_deadFor dead-zone voltages, T, caused by the dead-zone effect of the inverter_sIs the PWM switching period.

From this, the static inductance expression can be derived as:

wherein, the above three formulas are all formulas for calculating magnetic flux or flux linkage, and the formula is a general formula. Formula 1 formula 2 is some equivalent parameters that are fit by considering the basic form of an ideal motor model under a dq coordinate system, and is only for convenience of use. U is given by people, current is sampled, resistance and dead zone voltage are unknown, the unknown variables can be ignored through reasonable setting of the variables in the calculation, the Ts switching period is also a value given by people and is fixed, and i is the current of the motor and is obtained through sampling. Theta is the motor rotor position angle. The process time for identifying the time pulse is short, the position of the motor is almost fixed, and a group of inductors can be calculated to obtain the inductors under different current conditions.

The applied pulses are typically within 1-2ms, and in most cases the upper formula, although approximately equal, results in a substantially negligible error. Taking the dead zone voltage drop of 5V as an example, the voltage pulse value is 300V, the voltage error is about 5V/300V to 1.7%, and the precision is within 1.7%.

Alternatively, the polarity of the four small pulses of the voltage pulse group may also be changed. For example: the four small pulses in the voltage pulse group in the above example are positive, negative and positive pulses, and if the polarity is changed, the four small pulses may be negative, positive and negative pulses to form a group.

And step 14, taking the rotor position by 90 degrees.

And step 15, identifying the quadrature axis inductance. Specifically, the operation of step 13 may be repeated continuously under the quadrature axis to obtain quadrature axis inductance parameters of the motor under different current levels. For example: and applying a pulse voltage group to the quadrature axis, recording the current, and obtaining the size of the flux linkage so as to obtain a first group of quadrature axis inductance parameters. And then, repeatedly carrying out the operation, gradually increasing the current until the maximum allowable current of the motor is reached, and obtaining the quadrature axis inductance parameter values of the motor under different current levels.

Fig. 11 is a schematic diagram illustrating a process of identifying static inductance of a dc/ac shaft of a motor (e.g., a permanent magnet synchronous motor) according to an embodiment of the present invention. As shown in fig. 11, the process of identifying the dc/ac static inductance may include:

step 21, applying a voltage pulse group i.

And step 22, sampling the motor current I.

Step 23, calculating the inductance l (i).

And 24, judging whether the current is larger than a preset value or not. If yes, the inductance parameter table L (I) is saved, which contains the inductance values under a plurality of current conditions. Otherwise, the count value i of the voltage pulse group i is increased by 1, and the process returns to step 21 after the pulse voltage is increased.

And step 16, taking other angles for the rotor position, and identifying the cross-coupling inductance.

The identification process is identical to the identification of the direct-axis and quadrature-axis inductances, and the only difference is that the rotor position is different. This is related to the specific motor control strategy, and some control methods only have current in quadrature axis, and some direct axis and quadrature axis have current, and the inductance has cross coupling phase at this moment. The cross-coupling inductance is needed for common MTPA (maximum torque current ratio) control and flux weakening control.

And step 17, calculating the dynamic inductance. Specifically, an inductance-current curve may be fitted according to the direct axis inductance parameter values of the motor at different current levels obtained in step 13 and the quadrature axis inductance parameter values of the motor at different current levels obtained in step 15, and a dynamic inductance-current fitting curve may be obtained according to formula 2. And finally, obtaining the direct axis/quadrature axis static inductance and the dynamic inductance under different current levels according to the obtained curve (namely the dynamic inductance-current fitting curve).

Fitting the curve can be done using a least squares method, etc., and is mathematically a matter of interpolation, familiar to those skilled in the art and routine and will not be described in detail herein. Specifically, according to the data obtained by the user, discrete data points are obtained, such as 5mh of inductance corresponding to 1A current, 4.8mh of inductance corresponding to 2A current, and the like, so that the inductance value of 1.5A current is not needed, and the inductance value of 1.5A can be calculated by fitting a curve and using a relation obtained by fitting. This accuracy depends on the objectivity of the inductor current relationship, which does exist. This patent, adopts the least square method, utilizes polynomial to come the fitting. However, this is merely an example, and other fitting methods may be employed, with the emphasis on fitting to this relational curve, and not on what means to obtain it.

Fitting curve of dynamic inductance. In the formula 2, a rotation speed related term exists, and the motor is static when the inductance is identified, so that the term does not exist and the value is zero. Therefore, the formula 2 is only a current relational expression, and a delta inductance-current curve is obtained by simplifying the fitted static inductance current polynomial fitting relational expression.

The following table can be obtained from the measurement records:

direct axis current	i_d1	i_d2	…	i_dn
					Straight shaft inductor	L_d1	L_d2	…	L_dn
Quadrature axis current	i_q1	I_q2	…	i_qn
					Quadrature axis inductor	L_q1	L_q2	…	L_qn

Fitting the L (i) curve to the curve,

the inductance expression can be obtained:

wherein k is the power degree of the inductor current fitting polynomial, and a is the coefficient of the inductor current fitting polynomial.

This is a general notation and represents ld (i), lq (i) because the motor has two inductances, a direct axis and a quadrature axis. As shown in fig. 15(a) and (b).

For an ideal motor model that does not take into account the problem of magnetic circuit saturation, there is no need at all to use dynamic inductance, but for a real motor, this is very much necessary. The dynamic inductor describes that after the motor operates stably, the motor control system maintains the constant current and provides the regulated voltage when the motor generates small fluctuation up and down at the constant current. The PI parameter of the current loop is also designed based on this parameter. If the inductance is large, the current changes, and a larger amount of voltage should be supplied to adjust the current, and if the inductance is small, the amount of voltage supplied should be small. If the motor parameters are correct, the regulation process is ideal. For example, if the load is suddenly increased and the current is reduced, the PI regulator of the motor will increase a little voltage, increase the current, and maintain a new balance. If the parameters are not correct, the same current disturbance will cause a large voltage fluctuation, or the voltage fluctuation is too small, requiring a long time to regulate the current of the motor. In either case, the power loss of the motor is increased, and the motor current is out of control in severe cases.

Fig. 16 is a schematic diagram of a calculation flow of an inductance array of a motor (e.g., a permanent magnet synchronous motor) according to an embodiment of the present invention. As shown in fig. 16, the inductance array calculation process may include:

step 31, obtaining the current and obtaining a static d-axis inductance data set (i)_d、L_d) Or static q-axis inductance data set (i)_q、L_q)。

Step 32, calculating coefficients a of the fitting polynomial₀、a₁、……、a_n. n is a natural number.

Step 33, calculating the coefficient a of the dynamic inductance fitting polynomial₀、2a₂、3a₃、……、(n+1)a_n。

Step 34, obtaining the dynamic and dynamic inductance polynomial curves of the static inductance, which can be referred to as an example shown in fig. 15.

And step 35, calculating inductance values under different currents according to the inductance curve to form an inductance array.

Thus, the static inductance parameters and the dynamic inductance parameters under different current values are obtained after the execution of the inductance array calculation flow shown in fig. 16 is finished. In the running process of the motor, different inductance parameters can be selected according to the actual current of the motor to control the motor.

For example, when the compressor 10A is energized, the inductance Ld is 5mh, the inductance Lq is 10mh,

inductance L when current 20A_d＝4.9mh，L_q8mh, then different inductance values can be changed depending on the current. If L is always used_d＝5mh，L_qAt 10mh, the small current is not problematic, the current is large, and the small current parameter is also used, so that the position estimation is delayed, the current is delayed, the efficiency is reduced, and particularly, the MTPA control effect is greatly reduced.

Step 18, identifying the stator resistance of the motor, which can be seen in the example shown in fig. 13. In order to ensure that the motor rotor does not rotate in the identification process, pulse voltage is applied in the direction of the straight shaft of the motor until the current value reaches a considerable value, and the value I is recorded_r. Then, a zero voltage vector is applied to start the current decay, and at this time, the integral value S of the current with respect to time is obtained_r. Finally, the resistance r of the motor can be obtained according to the following resistance calculation formula:

specifically, referring to the example shown in fig. 7, the zero voltage vector is realized by a short circuit, specifically, 3 upper bridge arms are all turned on and 3 lower bridge arms are all turned off, or 3 lower bridge arms are all turned on and 3 upper bridge arms are all turned off. The zero vector of the conventional complementary mode PWM output fails the resistance discrimination due to the dead band voltage drop. In the scheme of the invention, the zero voltage applying mode is adopted, so that the failure of resistance identification caused by dead zone voltage drop can be avoided.

In addition, the main difficulty of resistance identification is that the resistance voltage drop is extremely difficult to obtain, and the dead zone voltage drop is generally far larger than the resistance voltage drop, so that the effect is common by using a common identification method based on ohm's law. In the scheme of the invention, the resistance is calculated by adopting the flux linkage, the flux linkage size under the given current is calculated by the identified static inductance, then a zero voltage vector is applied, and the resistance size is obtained by integral calculation. The identification resistor does not need a dynamic inductor, and only needs a static inductor to calculate the flux linkage, so that the identification resistor is obtained.

According to a voltage equation, calculating the resistance r of the motor:

wherein the content of the first and second substances,

Since the processing and functions of the air conditioning system of this embodiment are basically corresponding to the embodiments, principles and examples of the apparatus shown in fig. 5, the description of this embodiment is not given in detail, and reference may be made to the related descriptions in the embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention is adopted, and the injection voltage amplitude is increased and the action time is shortened when the voltage pulse is injected, so that the proportion of dead zone voltage drop, tube voltage drop and the like of the inverter in the actual output voltage can be reduced, a voltage integral calculation result with higher precision can be obtained, and the motor inductance parameter with higher precision can be calculated.

According to an embodiment of the present invention, there is also provided a storage medium corresponding to the motor parameter determination method, the storage medium including a stored program, wherein when the program runs, an apparatus in which the storage medium is located is controlled to execute the motor parameter determination method described above.

Since the processing and functions implemented by the storage medium of this embodiment substantially correspond to the embodiments, principles, and examples of the methods shown in fig. 1 to fig. 4, details are not described in the description of this embodiment, and reference may be made to the related descriptions in the foregoing embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention is adopted, and the static inductance and the dynamic inductance are calculated when inductance parameters are calculated, so that the static inductance can be utilized to determine the static parameters of the motor, and the dynamic inductance is utilized to control the dynamic performance of the motor, thereby better improving the control performance of the motor.

According to an embodiment of the present invention, there is also provided a processor corresponding to the motor parameter determination method, the processor being configured to run a program, wherein the program is configured to execute the motor parameter determination method described above when running.

Since the processing and functions implemented by the processor of this embodiment substantially correspond to the embodiments, principles, and examples of the methods shown in fig. 1 to fig. 4, details are not described in the description of this embodiment, and reference may be made to the related descriptions in the foregoing embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention can adopt a current integration method when the resistance of the stator winding is calculated, and on the basis of the flux linkage size obtained by calculation according to inductance parameters, zero-voltage vector motor current attenuation is applied, then current integration is carried out in the whole current attenuation process by means of Lenz's law, and finally the size of the winding resistance is obtained.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

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