阅读说明：本技术 控制电机降速的方法及装置 (Method and device for controlling motor deceleration ) 是由 唐婷婷 涂小平 王声纲 任艳华 王璠 潘军 杨正 朱绯 于 2020-04-29 设计创作，主要内容包括：本发明提供了一种控制电机降速的方法及装置,该方法包括：S1、在接收到脱水停机指令时,获取初始直流母线电压值；S2、将所述初始直流母线电压值作为目标直流母线电压值；S3、将预设的电压参考值和所述目标直流母线电压值输入到电压PI调节器中,输出交轴参考电流；S4、利用所述交轴参考电流控制所述电机降速；S5、在所述电机降速过程中,实时获取当前直流母线电压值；S6、将实时获取的当前直流母线电压值作为所述目标直流母线电压值,执行步骤S3,直至所述电机的转速降为零。本发明的方案能够能缩短电机降速的时长,从而缩短洗衣机从脱水完成至停下来所消耗的时间。(The invention provides a method and a device for controlling the speed reduction of a motor, wherein the method comprises the following steps: s1, acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received; s2, taking the initial direct current bus voltage value as a target direct current bus voltage value; s3, inputting a preset voltage reference value and the target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current; s4, controlling the motor to reduce the speed by using the quadrature axis reference current; s5, acquiring the current direct current bus voltage value in real time in the motor speed reduction process; and S6, taking the current direct current bus voltage value obtained in real time as the target direct current bus voltage value, and executing the step S3 until the rotating speed of the motor is reduced to zero. The scheme of the invention can shorten the time for the motor to slow down, thereby shortening the time consumed by the washing machine from the completion of dehydration to the stop of the washing machine.)

1. A method of controlling the deceleration of a motor, comprising:

s1, acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received;

s2, taking the initial direct current bus voltage value as a target direct current bus voltage value;

s3, inputting a preset voltage reference value and the target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current;

s4, controlling the motor to reduce the speed by using the quadrature axis reference current;

s5, acquiring the current direct current bus voltage value in real time in the motor speed reduction process;

and S6, taking the current direct current bus voltage value obtained in real time as the target direct current bus voltage value, and executing the step S3 until the rotating speed of the motor is reduced to zero.

2. The method of controlling motor deceleration according to claim 1, wherein said controlling said motor deceleration using said quadrature reference current comprises:

acquiring a direct axis reference current;

according to the quadrature-axis reference current and the direct-axis reference current, after PI regulation is carried out through a current PI regulator, quadrature-axis voltage and direct-axis voltage are determined;

carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

modulating the α axis voltage and the β axis voltage as space vector pulse width modulated signals;

and controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

3. The method for controlling the motor deceleration according to claim 2, wherein the value ranges of the proportional gain and the integral time of the voltage PI regulator are set so that the difference between the voltage reference value and the target DC bus voltage value is smaller than a set difference;

setting the value of the proportional gain in the current PI regulator when the motor is decelerated to be larger than the value of the proportional gain in the current PI regulator before the motor is decelerated, and setting the value of the integral time in the current PI regulator when the motor is decelerated to be larger than the value of the integral time in the current PI regulator before the motor is decelerated to ensure that the target direct-current bus voltage value is changed within a set change rate range.

4. The method for controlling the motor deceleration according to claim 2, further comprising, after the inverse park transformation of the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage in a two-phase stationary coordinate system:

obtaining a desired output voltage according to the α axis voltage and the β axis voltage;

if the magnitude of the desired output voltage is greater than the DC bus voltageAnd if so, generating weak magnetic current by using a weak magnetic control module, and taking the weak magnetic current as the direct-axis reference current.

5. The method for controlling the motor deceleration according to any one of claims 1 to 4, wherein the ratio of the voltage reference value to the maximum withstand voltage value of the direct current bus is set to 85% to 90%.

6. An apparatus for controlling the deceleration of a motor, comprising:

the device comprises an acquisition module, a voltage PI regulator and a control module, wherein the acquisition module is used for acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received, taking the initial direct current bus voltage value as a target direct current bus voltage value, and inputting the target direct current bus voltage value and a preset voltage reference value into the voltage PI regulator;

the voltage PI regulator is used for outputting a quadrature axis reference current according to the voltage reference value and the target direct current bus voltage value;

the control module is used for controlling the motor to reduce the speed by utilizing the quadrature axis reference current;

the obtaining module is further configured to obtain a current dc bus voltage value in real time during a speed reduction process of the motor, use the current dc bus voltage value obtained in real time as the target dc bus voltage value and input the target dc bus voltage value to the voltage PI regulator, and terminate the operation when the control module reduces the rotation speed of the motor to zero.

7. The apparatus for controlling motor deceleration of claim 6 wherein said control module comprises:

the first acquisition submodule is used for acquiring a direct-axis reference current;

the current PI regulator is used for determining quadrature axis voltage and direct axis voltage according to the quadrature axis reference current and the direct axis reference current;

the voltage transformation submodule is used for carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

a signal modulation submodule for modulating the α axis voltage and the β axis voltage into space vector pulse width modulation signals;

and the rotating speed control submodule is used for controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

8. The apparatus for controlling motor deceleration according to claim 7, further comprising a setting module;

the setting module is used for setting the value ranges of the proportional gain and the integral time of the voltage PI regulator so as to enable the difference value between the voltage reference value and the target direct-current bus voltage value to be smaller than a set difference value;

the setting module is further configured to set a value of a proportional gain in the current PI regulator when the motor is decelerated to be larger than a value of a proportional gain in the current PI regulator before the motor is decelerated, and set a value of an integration time in the current PI regulator when the motor is decelerated to be larger than a value of an integration time in the current PI regulator before the motor is decelerated to change the target dc bus voltage value within a set change rate range.

9. The apparatus for controlling motor deceleration of claim 7, wherein said control module further comprises:

a second obtaining submodule, configured to obtain a desired output voltage according to the α axis voltage and the β axis voltage;

a weak magnetic control module for controlling the output voltage if the desired output voltage has a magnitude greater than the DC bus voltageAnd if so, generating weak magnetic current by using the weak magnetic control module, and taking the weak magnetic current as the direct-axis reference current.

10. The device for controlling the motor deceleration according to any one of claims 6 to 9, wherein the ratio of the voltage reference value to the maximum withstand voltage value of the direct current bus is 85% to 90%.

Technical Field

The invention relates to the technical field of motor control, in particular to a method and a device for controlling the speed reduction of a motor.

Background

The drum washing machine has high rotation speed in the dewatering process, generally 1400-1600 rpm. When the washing machine which runs at a high speed is stopped after the dehydration is finished, the motor of the washing machine needs to be braked.

Disclosure of Invention

The embodiment of the invention provides a method and a device for controlling the speed reduction of a motor, which can shorten the speed reduction time of the motor, thereby shortening the time consumed by the washing machine from the completion of dehydration to the stop of the washing machine.

In a first aspect, an embodiment of the present invention provides a method for controlling a motor deceleration, including:

s1, acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received;

s2, taking the initial direct current bus voltage value as a target direct current bus voltage value;

s3, inputting a preset voltage reference value and the target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current;

s4, controlling the motor to reduce the speed by using the quadrature axis reference current;

s5, acquiring the current direct current bus voltage value in real time in the motor speed reduction process;

and S6, taking the current direct current bus voltage value obtained in real time as the target direct current bus voltage value, and executing the step S3 until the rotating speed of the motor is reduced to zero.

In one possible design, the controlling the motor deceleration by using the quadrature reference current includes:

acquiring a direct axis reference current;

according to the quadrature-axis reference current and the direct-axis reference current, after PI regulation is carried out through a current PI regulator, quadrature-axis voltage and direct-axis voltage are determined;

carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

modulating the α axis voltage and the β axis voltage as space vector pulse width modulated signals;

and controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

In one possible design, setting the value ranges of the proportional gain and the integral time of the voltage PI regulator, so that the difference value between the voltage reference value and the target direct current bus voltage value is smaller than a set difference value;

setting the value of the proportional gain in the current PI regulator when the motor is decelerated to be larger than the value of the proportional gain in the current PI regulator before the motor is decelerated, and setting the value of the integral time in the current PI regulator when the motor is decelerated to be larger than the value of the integral time in the current PI regulator before the motor is decelerated to ensure that the target direct-current bus voltage value is changed within a set change rate range.

In one possible design, after the inverse park transformation is performed on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage in a two-phase stationary coordinate system, the method further includes:

obtaining a desired output voltage according to the α axis voltage and the β axis voltage;

if the magnitude of the desired output voltage is greater than the DC bus voltageAnd if so, generating weak magnetic current by using a weak magnetic control module, and taking the weak magnetic current as the direct-axis reference current.

In one possible design, the ratio of the voltage reference value to the maximum withstand voltage value of the direct current bus is set to be 85% -90%.

In a second aspect, an embodiment of the present invention provides an apparatus for controlling a deceleration of a motor, including:

the device comprises an acquisition module, a voltage PI regulator and a control module, wherein the acquisition module is used for acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received, taking the initial direct current bus voltage value as a target direct current bus voltage value, and inputting the target direct current bus voltage value and a preset voltage reference value into the voltage PI regulator;

the voltage PI regulator is used for outputting a quadrature axis reference current according to the voltage reference value and the target direct current bus voltage value;

the control module is used for controlling the motor to reduce the speed by utilizing the quadrature axis reference current;

the obtaining module is further configured to obtain a current dc bus voltage value in real time during a speed reduction process of the motor, use the current dc bus voltage value obtained in real time as the target dc bus voltage value and input the target dc bus voltage value to the voltage PI regulator, and terminate the operation when the control module reduces the rotation speed of the motor to zero.

In one possible design, the control module includes:

the first acquisition submodule is used for acquiring a direct-axis reference current;

the current PI regulator is used for determining quadrature axis voltage and direct axis voltage according to the quadrature axis reference current and the direct axis reference current;

the voltage transformation submodule is used for carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

a signal modulation submodule for modulating the α axis voltage and the β axis voltage into space vector pulse width modulation signals;

and the rotating speed control submodule is used for controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

In one possible design, the system further comprises a setting module;

the setting module is used for setting the value ranges of the proportional gain and the integral time of the voltage PI regulator so as to enable the difference value between the voltage reference value and the target direct-current bus voltage value to be smaller than a set difference value;

the setting module is further configured to set a value of a proportional gain in the current PI regulator when the motor is decelerated to be larger than a value of a proportional gain in the current PI regulator before the motor is decelerated, and set a value of an integration time in the current PI regulator when the motor is decelerated to be larger than a value of an integration time in the current PI regulator before the motor is decelerated to change the target dc bus voltage value within a set change rate range.

In one possible design, the control module further includes:

a second obtaining submodule, configured to obtain a desired output voltage according to the α axis voltage and the β axis voltage;

a weak magnetic control module for controlling the output voltage if the desired output voltage has a magnitude greater than the DC bus voltageAnd if so, generating weak magnetic current by using the weak magnetic control module, and taking the weak magnetic current as the direct-axis reference current.

In one possible design, the ratio of the voltage reference value to the maximum withstand voltage value of the direct current bus is 85% -90%.

According to the scheme, when the dehydration shutdown instruction is received, the initial direct-current bus voltage value is obtained and is used as the target direct-current bus voltage value; inputting a preset voltage reference value and a target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current; controlling the motor to reduce the speed by using the quadrature axis reference current; and in the speed reduction process of the motor, acquiring the current direct current bus voltage value in real time, taking the current direct current bus voltage value acquired in real time as a target direct current bus voltage value and inputting the target direct current bus voltage value into the voltage PI regulator until the rotating speed of the motor is reduced to zero. Through the method for obtaining the quadrature axis reference current, in the process of motor deceleration (namely braking), the target direct current bus voltage value has oscillation fluctuation near the voltage reference value and does not exceed the maximum withstand voltage value of the direct current bus, namely, the motor can be decelerated at the maximum deceleration on the premise of ensuring the safety of the direct current bus voltage, so that the time length of motor deceleration can be shortened, namely, the time consumed by the washing machine from the completion of dehydration to the stop of the washing machine is shortened.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flow chart of a method of controlling motor deceleration provided by one embodiment of the present invention;

FIG. 2 is a flow chart of a method for controlling motor deceleration using a direct-axis reference current and a quadrature-axis reference current according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method for controlling motor deceleration using a field weakening control module according to an embodiment of the present invention;

fig. 4 is a control circuit diagram of a motor according to an embodiment of the present invention;

FIG. 5 is a flow chart of another method for controlling motor deceleration provided by an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an apparatus for controlling a motor deceleration according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of another apparatus for controlling the deceleration of a motor according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of another apparatus for controlling motor deceleration according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of another apparatus for controlling a motor deceleration according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.

As shown in fig. 1, an embodiment of the present invention provides a method for controlling a motor to slow down, which may include the following steps:

s1, acquiring an initial direct current bus voltage value when a dehydration shutdown instruction is received;

s2, taking the initial direct current bus voltage value as a target direct current bus voltage value;

s3, inputting a preset voltage reference value and a target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current;

s4, controlling the speed reduction of the motor by using the quadrature axis reference current;

s5, acquiring the current direct current bus voltage value in real time in the motor speed reduction process;

s6, taking the current direct current bus voltage value obtained in real time as a target direct current bus voltage value;

and S7, executing steps S3-S6 until the rotating speed of the motor is reduced to zero.

In the embodiment of the invention, when a motor receives a dehydration shutdown instruction, an initial direct current bus voltage value is obtained and is taken as a target direct current bus voltage value; inputting a preset voltage reference value and a target direct current bus voltage value into a voltage PI regulator, and outputting a quadrature axis reference current; controlling the motor to reduce the speed by using the quadrature axis reference current; and in the speed reduction process of the motor, acquiring the current direct current bus voltage value in real time, taking the current direct current bus voltage value acquired in real time as a target direct current bus voltage value and inputting the target direct current bus voltage value into the voltage PI regulator until the rotating speed of the motor is reduced to zero. Through the method for obtaining the quadrature axis reference current, in the process of motor deceleration (namely braking), the target direct current bus voltage value has oscillation fluctuation near the voltage reference value and does not exceed the maximum withstand voltage value of the direct current bus, namely, the motor can be decelerated at the maximum deceleration on the premise of ensuring the safety of the direct current bus voltage, so that the time length of motor deceleration can be shortened, namely, the time consumed by the washing machine from the completion of dehydration to the stop of the washing machine is shortened.

In the embodiment of the invention, because it is necessary to ensure that the voltage value of the direct-current bus does not exceed the maximum withstand voltage value of the direct-current bus in the process of controlling the motor to reduce the speed, a voltage reference value needs to be preset to limit the voltage value of the direct-current bus, and the ratio of the voltage reference value to the maximum withstand voltage value of the direct-current bus voltage is a proportionality coefficient smaller than 1, wherein the proportionality coefficient can be obtained by a worker through simulation or actual experience. In some implementations, the ratio of the voltage reference to the maximum withstand voltage of the dc bus is 85% to 90%.

It should be noted that, according to different application scenarios of the motor, the ratio of the voltage reference value to the maximum withstand voltage value of the dc bus may be different or the same.

In addition, when the motor is decelerated by adopting the control method, when the voltage reference value is not changed, the counter electromotive force generated by the motor is gradually reduced along with the continuous reduction of the rotating speed of the motor, so that the deceleration of the motor is gradually increased, and the deceleration duration of the motor can be further shortened. For example, when the motor starts to drop from 1400rpm, the voltage reference value is 400V, the deceleration for starting to drop is 200rpm, and as the rotating speed is continuously reduced, when the rotating speed of the motor is 800rpm, the deceleration of the motor is greater than 200rpm, for example, 250 rpm. That is, as the rotating speed of the motor is continuously reduced, the counter electromotive force generated by the motor is gradually reduced, and the speed reduction of the motor by voltage control in the above embodiment not only enables the motor to be reduced at the maximum deceleration, but also enables the deceleration of the motor to be gradually increased in the speed reduction process, so that the time length of the motor deceleration can be greatly shortened.

In some embodiments, in the method for controlling the motor deceleration by using the quadrature reference current shown in fig. 1, the motor deceleration can be controlled at least in one of the following ways. As shown in fig. 2, the method may include the steps of:

s41, acquiring a direct-axis reference current;

s42, according to the quadrature axis reference current and the direct axis reference current, after PI regulation is carried out through a current PI regulator, quadrature axis voltage and direct axis voltage are determined;

s43, carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

s44, modulating the α axis voltage and the β axis voltage into space vector pulse width modulation signals;

and S45, controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

In the embodiment of the invention, according to the quadrature axis reference current and the direct axis reference current, the quadrature axis voltage and the direct axis voltage are obtained after PI regulation is carried out through a current PI regulator, then the coordinate conversion can be realized through park inverse transformation (namely 2d/2s transformation) of the obtained quadrature axis voltage and the obtained direct axis voltage, namely the quadrature axis voltage and the direct axis voltage are converted into α axis voltage and β axis voltage on α axes and β axes in a two-phase static coordinate system, then the α axis voltage and the β axis voltage can be modulated into Space Vector Pulse Width Modulation (SVPWM) signals, the space vector pulse width modulation signals are six-way switching signals with corresponding duty ratios, therefore, the turn-off and turn-on of a three-phase inverter can be controlled by utilizing the space vector pulse width modulation signals, and the control of the rotating speed of a motor is realized by controlling the turn-off time and the turn-on time of the three-phase inverter.

In the embodiment of the invention, the axle voltage α and the axle voltage β are obtained by carrying out park inverse transformation on the quadrature-axis voltage and the direct-axis voltage, a space vector pulse width modulation signal is further determined according to the axle voltage α and the axle voltage β, and the rotation speed of the motor is controlled by controlling the turn-off time and the turn-on time of the three-phase inverter based on the space vector pulse width modulation signal, so that the determined space vector pulse width modulation signal can be ensured to be matched with the current operation state of the motor, and the periodicity of the rotation speed of the motor is further ensured to be controlled based on the space vector pulse width modulation signal.

In the embodiment of the invention, the value ranges of the proportional gain and the integral time of the voltage PI regulator are set, so that the difference value between the voltage reference value and the target direct-current bus voltage value is smaller than the set difference value.

When the motor is in the speed reduction stage, in order to ensure that the speed reduction is maximum and the target direct-current bus voltage value does not exceed the maximum withstand voltage value of the direct-current bus voltage (namely, the maximum withstand voltage value of the filter capacitor 3), the target direct-current bus voltage value should be controlled to be close to the voltage reference value, namely, the difference value between the voltage reference value and the target direct-current bus voltage value is smaller than a set difference value, so that the target direct-current bus voltage value can be ensured to have oscillation fluctuation at the voltage reference value and also not exceed the maximum withstand voltage value of the direct-current bus, namely, the overshoot of the motor can be reduced by adjusting the proportional gain (Kp) and the integral time (Ti) of the voltage PI adjuster, and thus the safety of the direct-current bus voltage is ensured. For example, the set difference may be 20V, and when the voltage reference value is 400V, the target dc bus voltage value may fluctuate between 380V and 420V, so that by adjusting the proportional gain (Kp) and the integration time (Ti) of the voltage PI regulator, the overshoot of the motor may be reduced, thereby increasing the stability of the voltage control. It should be noted that the specific adjustment amount of the proportional gain (Kp) and the integral time (Ti) of the voltage PI regulator depends on the model, type and control algorithm of different motors, and the embodiment of the present invention is not limited to this specific adjustment amount, i.e. it is only required to ensure that the difference between the voltage reference value and the target dc bus voltage value can be controlled to be smaller than the set difference by adjusting the proportional gain (Kp) and the integral time (Ti) of the voltage PI regulator.

In the embodiment of the invention, the value of the proportional gain in the current PI regulator when the motor is decelerated is set to be larger than the value of the proportional gain in the current PI regulator before the motor is decelerated, and the value of the integral time in the current PI regulator when the motor is decelerated is set to be larger than the value of the integral time in the current PI regulator before the motor is decelerated, so that the target direct-current bus voltage value is changed within the set change rate range.

When the motor is in the speed reduction stage, in order to further ensure that the speed reduction is maximum and the target dc bus voltage value does not exceed the maximum withstand voltage value of the dc bus voltage (i.e. the maximum withstand voltage value of the filter capacitor 3), the target dc bus voltage value should be further controlled to change within a set change rate range, i.e. the change rate of the target dc bus voltage value is prevented from being too fast, which may cause the target dc bus voltage value to exceed the maximum withstand voltage value of the dc bus voltage, so that the safety of the dc bus voltage can be further ensured. It should be noted that the specific adjustment amount of the proportional gain (Kp) and the integration time (Ti) of the current PI regulator depends on the model, type and control algorithm of different motors, and the embodiment of the present invention is not limited to this specific adjustment amount, that is, it is only required to ensure that the change rate of the target dc bus voltage value can be controlled within the set change rate range by adjusting the proportional gain (Kp) and the integration time (Ti) of the current PI regulator.

In some implementations, the current PI regulator for setting the motor at the speed reduction is at least a current PI regulator for outputting a quadrature axis voltage, that is, the current PI regulator for outputting the quadrature axis voltage only, or the current PI regulator for outputting the quadrature axis voltage and the current PI regulator for outputting a direct axis voltage.

In some embodiments, in the method of controlling motor deceleration using quadrature and direct reference currents as shown in FIG. 2, the direct reference current is determined in relation to α and β axis voltages, the direct reference current may be determined as follows when one of the following occurs, as shown in FIG. 3:

s431, obtaining a desired output voltage according to the α axis voltage and the β axis voltage;

s432, if the amplitude of the expected output voltage is larger than the DC bus voltageAnd if so, generating weak magnetic current by using a weak magnetic control module, and taking the weak magnetic current as direct-axis reference current.

In embodiments of the invention, it may occur that the magnitude of the desired output voltage is greater than the dc bus voltage when the motor is in the down phaseUnder the condition of double, the motor can generate weak magnetic current by using a weak magnetic control module at the moment, and when the direct axis reference current and the quadrature axis reference current determined at the moment are used for controlling the motor to reduce the speed, the adopted mode is a weak magnetic control mode,therefore, the stability of the voltage of the direct current bus can be ensured.

It should be noted that the method for controlling the motor deceleration provided by the embodiment of the present invention can be applied to the control of motors in household appliances such as washing machines, refrigerators, air conditioners, and the like.

Based on the foregoing embodiment, please refer to fig. 4 as a control circuit diagram of a preferred motor according to an embodiment of the present invention, a quadrature axis reference current in a current loop is obtained by a voltage feedback PI control, and an overall control process of a method for controlling a motor speed reduction according to an embodiment of the present invention is described below with reference to fig. 4, where a flowchart of the method refers to fig. 5, and may include the following steps:

and S101, presetting a voltage reference value.

The voltage reference value is a reference value for limiting the voltage value of the direct current bus in the speed reduction process of the motor, namely, the voltage value of the direct current bus does not excessively exceed the voltage reference value in the speed reduction process of the motor, so that the direct current bus keeps oscillating fluctuation in the upper and lower ranges of the voltage reference value.

In this embodiment, the voltage reference value may be determined by a maximum withstand voltage value of the dc bus voltage, wherein, for example, a ratio of the voltage reference value to the maximum withstand voltage value of the dc bus is 85% to 90%.

The maximum withstand voltage value of the dc bus is determined according to a filter capacitor 3 (please refer to fig. 4) connected to the dc bus, where the maximum withstand voltage value of the filter capacitor 3 is the maximum withstand voltage value of the dc bus. The maximum voltage withstanding value of the filter capacitor 3 is usually 450V, and certainly, the filter capacitor 3 in the circuit diagram may also select a capacitor with a maximum voltage withstanding value of other values according to actual requirements, which is not illustrated here. When the maximum withstand voltage value of the filter capacitor 3 connected with the direct-current bus is 450V, the value of the voltage reference value can be selected to be 380-405V, so that the target direct-current bus voltage value can oscillate at the voltage reference value and can not exceed the maximum withstand voltage value of the filter capacitor 3 connected with the direct-current bus, namely, the motor can be decelerated at the maximum deceleration on the premise of ensuring the safety of the direct-current bus voltage.

S102, when a dehydration stop instruction is received, obtaining an initial direct current bus voltage value, and taking the initial direct current bus voltage value as a target direct current bus voltage value.

Before the motor is decelerated, the motor is in high-speed rotation, a corresponding voltage value is arranged on the direct current bus at the moment, and the initial direct current bus voltage value is the voltage value corresponding to the direct current bus acquired when the dehydration stop instruction is received. Taking the initial DC bus voltage value as a target DC bus voltage value V_dcFed back into the voltage PI regulator 1.

And S103, inputting a preset voltage reference value and a target direct current bus voltage value into the voltage PI regulator, and outputting a quadrature axis reference current.

In the embodiment of the invention, the preset voltage reference value is usedAnd a target DC bus voltage value V_dcMaking a difference, and calculating the obtained difference value after the voltage PI regulator 1 is regulated to obtain a quadrature axis reference currentWherein, the value ranges of the proportional gain (Kp) and the integral time (Ti) of the voltage PI regulator 1 are set so as to make the voltage reference valueAnd a target DC bus voltage value V_dcIs less than the set difference value, so that the target direct current bus voltage value V can be ensured_dcAt a voltage reference valueThe oscillation fluctuation does not exceed the maximum withstand voltage value of the direct current bus, namely, the overshoot of the motor can be reduced by adjusting the proportional gain (Kp) and the integral time (Ti) of the voltage PI regulator 1, so that the safety of the voltage of the direct current bus is ensured.

And S104, acquiring direct-axis reference current, and determining quadrature-axis voltage and direct-axis voltage after performing PI regulation through a current PI regulator according to the quadrature-axis reference current and the direct-axis reference current.

In the embodiment of the invention, the direct axis reference current can be obtained through maximum torque current ratio (MTPA) control, or the direct axis reference current can be directly set to be equal to zero, and the two modes can be flexibly selected to obtain the direct axis reference current in an actual application scene, so that different motor control application scenes can be met, and the motor control method has stronger applicability.

Of course, the direct axis reference current can also be obtained from the axis voltage U according to α_αAnd β Axis Voltage U_βTo obtain a desired output voltage U_s(wherein). If an output voltage U is desired_sOf greater amplitude than the DC bus voltageThen, a weak magnetic current is generated by using a weak magnetic control module, and the weak magnetic current is used as a direct-axis reference current (please refer to step S105, i.e. after step S105 is executed, the direct-axis reference current may be obtained).

In the embodiment of the invention, the quadrature axis is referenced to the currentAnd the actual quadrature axis current i_qMaking a difference and referencing the direct axis to a currentAnd the actual direct axis current i_dMaking a difference, and calculating the obtained difference value after the current PI regulator 2 is regulated to obtain a quadrature axis voltage V_qAnd the direct axis voltage V_d. Wherein, the value of the proportional gain (Kp) in the current PI regulator 2 when the motor is decelerated is set to be larger than the value of the proportional gain (Kp) in the current PI regulator 2 before the motor is decelerated, the value of the integral time (Ti) in the current PI regulator 2 when the motor is decelerated is set to be larger than the value of the integral time (Ti) in the current PI regulator 2 before the motor is decelerated,so as to lead the target DC bus voltage value V_dcVarying within a set range of rates of change. So set up, can avoid target direct current busbar voltage value V_dcToo fast, and may result in the target dc bus voltage value V_dcAnd the voltage exceeds the maximum voltage withstanding value of the direct current bus voltage, so that the safety of the direct current bus voltage can be further ensured.

And S105, carrying out park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system.

In the embodiment of the invention, the voltage V is obtained by comparing the quadrature axis voltage V_qAnd the direct axis voltage V_dPerforming inverse park transformation to obtain α axis voltage U of two-phase stationary coordinate system_αAnd β Axis Voltage U_β。

And S106, modulating the α axis voltage and the β axis voltage into space vector pulse width modulation signals.

In the embodiment of the invention, the shaft voltage U is obtained at α_αAnd β Axis Voltage U_βThereafter, α shaft voltage U_αAnd β Axis Voltage U_βGenerating Space Vector Pulse Width Modulation (SVPWM) signal, wherein voltage U is α -axis_αAnd β Axis Voltage U_βWhen the saturation exceeds the upper limit of the limit range, the upper limit is defined as the α axis voltage U_αAnd β Axis Voltage U_βAnd the SVPWM signal is output to the SVPWM module through the voltage limiting module to generate a space vector pulse width modulation SVPWM signal.

And S107, controlling the turn-off and turn-on of a three-phase inverter connected with the motor according to the space vector pulse width modulation signal so as to control the speed reduction of the motor.

In the embodiment of the invention, the shaft voltage U is α_αAnd β Axis Voltage U_βThe three-phase inverter is modulated into six switching signals through the SVPWM module, the three-phase inverter is controlled to be switched off and switched on, and the rotating speed of the motor is controlled by controlling the switching-off time and the switching-on time of the three-phase inverter.

And S108, in the speed reduction process of the motor, acquiring the current direct current bus voltage value in real time, taking the current direct current bus voltage value acquired in real time as a target direct current bus voltage value, and executing the step S103 until the rotating speed of the motor is reduced to zero.

In the embodiment of the invention, the real-time voltage of the direct current bus is sampled to obtain the current direct current bus voltage value in real time, and the current direct current bus voltage value obtained in real time is taken as the target direct current bus voltage value V_dc。

In the embodiment of the invention, the steps S103-S108 are executed circularly, namely only the target DC bus voltage value V needs to be considered_dcThe maximum withstand voltage value of the filter capacitor 3 connected with the direct current bus can not be exceeded until the rotating speed of the motor is reduced to zero. The embodiment of the invention can reduce the speed of the motor at the maximum deceleration under the premise of ensuring the safety of the DC bus voltage, thereby shortening the speed reduction time of the motor, namely shortening the time consumed by the washing machine from the completion of dehydration to the stop of the washing machine.

In an embodiment of the present invention, as shown in fig. 4, three-phase current (I) to the motor_U、I_V、I_W) After collection, the three-phase current is converted through clark coordinates to obtain two-phase current (I)_α、I_β) (ii) a Then, the two-phase current is subjected to park coordinate conversion to obtain an actual direct-axis current i_dAnd the actual quadrature axis current i_q. A position estimation unit (e.g., a speed flux linkage observer) may estimate the position of the rotor through a sensorless estimation algorithm to obtain an estimated angle θ. Wherein, the current i is actually in the direct axis_dAnd the actual quadrature axis current i_qWhen the current exceeds the upper limit of the limit range and is saturated, the upper limit is set as the actual direct-axis current i_dAnd the actual quadrature axis current i_qAnd the output is output after passing through the current limiting module.

As shown in fig. 6, an embodiment of the present invention provides an apparatus for controlling a motor deceleration, including:

an obtaining module 201, configured to obtain an initial dc bus voltage value when a dehydration shutdown instruction is received, take the initial dc bus voltage value as a target dc bus voltage value, and input the target dc bus voltage value and a preset voltage reference value into the voltage PI regulator 202;

the voltage PI regulator 202 is used for outputting a quadrature axis reference current according to the voltage reference value and the target direct current bus voltage value;

the control module 203 is used for controlling the motor to reduce the speed by using the quadrature axis reference current;

the obtaining module 201 is further configured to obtain a current dc bus voltage value in real time during a motor speed reduction process, use the current dc bus voltage value obtained in real time as a target dc bus voltage value and input the target dc bus voltage value into the voltage PI regulator 202, and terminate the operation when the control module reduces the rotation speed of the motor to zero.

In the embodiment of the present invention, the obtaining module 201 may be configured to perform steps S1, S2, S5, S6, and S7 in the above method embodiment, the quadrature axis current calculating module 202 may be configured to perform step S3 in the above method embodiment, and the control module 203 may be configured to perform step S4 in the above method embodiment.

In some embodiments, based on the apparatus for controlling the motor deceleration shown in fig. 6, as shown in fig. 7, the control module 203 comprises:

a first obtaining submodule 2031 configured to obtain a direct-axis reference current;

a current PI regulator 2032 configured to determine a quadrature-axis voltage and a direct-axis voltage according to the quadrature-axis reference current and the direct-axis reference current;

the voltage transformation submodule 2033 is used for performing park inverse transformation on the quadrature axis voltage and the direct axis voltage to obtain α axis voltage and β axis voltage under a two-phase static coordinate system;

a signal modulation submodule 2034 for modulating the α -axis voltage and the β -axis voltage into space vector pulse width modulation signals;

the rotation speed control submodule 2035 is configured to control turning-off and turning-on of a three-phase inverter connected to the motor according to the space vector pulse width modulation signal, so as to control the motor to slow down.

In this embodiment of the present invention, the first obtaining sub-module 2031 may be configured to perform step S41 in the above method embodiment, the current PI regulator 2032 may be configured to perform step S42 in the above method embodiment, the voltage converting sub-module 2033 may be configured to perform step S43 in the above method embodiment, the signal modulating sub-module 2034 may be configured to perform step S44 in the above method embodiment, and the rotation speed control sub-module 2035 may be configured to perform step S45 in the above method embodiment.

In some embodiments, on the basis of the apparatus for controlling motor deceleration shown in fig. 7, as shown in fig. 8, the apparatus for controlling motor deceleration further includes a setting module 204, and the setting module 204 is respectively connected to the quadrature axis current calculating module 202 and the current PI regulator 2032, wherein:

the setting module 204 is configured to set a value range of a proportional gain and an integral time of the voltage PI regulator, so that a difference between the voltage reference value and the target dc bus voltage value is smaller than a set difference;

the setting module 204 is further configured to set a value of a proportional gain in the current PI regulator when the motor is decelerated to be larger than a value of a proportional gain in the current PI regulator before the motor is decelerated, and set a value of an integration time in the current PI regulator when the motor is decelerated to be larger than a value of an integration time in the current PI regulator before the motor is decelerated to change the target dc bus voltage value within a set change rate range.

In some embodiments, based on the apparatus for controlling the motor deceleration shown in fig. 7, as shown in fig. 9, the control module 203 further comprises:

a second obtaining sub-module 2036 for obtaining a desired output voltage from the α -axis voltage and the β -axis voltage;

the flux weakening control module 2037 controls the output voltage if the desired amplitude is greater than the DC bus voltageAnd if so, generating weak magnetic current by using a weak magnetic control module, and taking the weak magnetic current as direct-axis reference current.

In this embodiment of the present invention, the second obtaining sub-module 2036 may be configured to perform step S431 in the foregoing method embodiment, and the field weakening control module 2037 may be configured to perform step S432 in the foregoing method embodiment.

It is to be understood that the illustrated structure of the embodiment of the present invention does not constitute a specific limitation to the device for controlling the motor deceleration. In other embodiments of the invention, the motor control apparatus may include more or fewer components than shown, or some components may be combined, some components may be separated, or a different arrangement of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

Because the information interaction, execution process, and other contents between the units in the device are based on the same concept as the method embodiment of the present invention, specific contents may refer to the description in the method embodiment of the present invention, and are not described herein again.

It should be noted that not all steps and modules in the above flows and system structure diagrams are necessary, and some steps or modules may be omitted according to actual needs. The execution order of the steps is not fixed and can be adjusted as required. The system structure described in the above embodiments may be a physical structure or a logical structure, that is, some modules may be implemented by the same physical entity, or some modules may be implemented by a plurality of physical entities, or some components in a plurality of independent devices may be implemented together.

In the above embodiments, the hardware unit may be implemented mechanically or electrically. For example, a hardware element may comprise permanently dedicated circuitry or logic (such as a dedicated processor, FPGA or ASIC) to perform the corresponding operations. The hardware elements may also comprise programmable logic or circuitry, such as a general purpose processor or other programmable processor, that may be temporarily configured by software to perform the corresponding operations. The specific implementation (mechanical, or dedicated permanent, or temporarily set) may be determined based on cost and time considerations.

While the invention has been shown and described in detail in the drawings and in the preferred embodiments, it is not intended to limit the invention to the embodiments disclosed, and it will be apparent to those skilled in the art that various combinations of the code auditing means in the various embodiments described above may be used to obtain further embodiments of the invention, which are also within the scope of the invention.