阅读说明：本技术 一种永磁同步电机降额控制方法、装置及永磁同步电机 (Derating control method and device for permanent magnet synchronous motor and permanent magnet synchronous motor ) 是由 范雨卉 李帅 李岩 潘忠亮 李伟亮 于 2019-11-01 设计创作，主要内容包括：本发明公开了一种永磁同步电机降额控制方法、装置及永磁同步电机,方法包括：获取电机的调制系数,并将调制系数与预设阈值进行比较,得到比较结果；若比较结果为调制系数大于第一预设阈值且小于第二预设阈值,则基于调制系数确定电机的降额扭矩；根据降额扭矩在三维电流查表中查询得到电流指令值；基于查询得到的电流指令值控制逆变器输出相应的电流,以控制电机降额运行。本发明提高了对永磁同步电机弱磁控制的可靠性及稳定性,避免了控制永磁同步电机的逆变器达到饱和造成非预期输出或损坏,保证了车辆在极低温工况、急加减速及恶劣路况下都能正常运行。(The invention discloses a derating control method and device for a permanent magnet synchronous motor and the permanent magnet synchronous motor, wherein the method comprises the following steps: acquiring a modulation coefficient of the motor, and comparing the modulation coefficient with a preset threshold value to obtain a comparison result; if the comparison result is that the modulation factor is larger than a first preset threshold and smaller than a second preset threshold, determining derating torque of the motor based on the modulation factor; inquiring in a three-dimensional current lookup table according to the derating torque to obtain a current instruction value; and controlling the inverter to output corresponding current based on the inquired current command value so as to control the derating operation of the motor. The invention improves the reliability and stability of the flux weakening control of the permanent magnet synchronous motor, avoids unexpected output or damage caused by saturation of an inverter for controlling the permanent magnet synchronous motor, and ensures that the vehicle can normally run under extremely low temperature working conditions, rapid acceleration and deceleration and severe road conditions.)

1. A derating control method for a permanent magnet synchronous motor is characterized by comprising the following steps:

obtaining a modulation coefficient of a motor, and comparing the modulation coefficient with a preset threshold to obtain a comparison result, wherein the preset threshold comprises a first preset threshold and a second preset threshold, and the first preset threshold is smaller than the second preset threshold;

if the comparison result is that the modulation factor is larger than a first preset threshold and smaller than a second preset threshold, determining derating torque of the motor based on the modulation factor;

inquiring in a three-dimensional current lookup table according to the derating torque to obtain a current instruction value, wherein the current instruction value comprises a direct-axis current component instruction value and a quadrature-axis current component instruction value, and the three-dimensional current lookup table is established by an experimental calibration method;

and controlling the inverter to output corresponding current based on the current command value obtained by query so as to control the derating operation of the motor.

2. The method according to claim 1, wherein before the controlling the inverter to output the corresponding current based on the queried current command value to control the derating operation of the motor, the method further comprises:

if the comparison result shows that the modulation coefficient is larger than a second preset threshold value, acquiring a voltage limit value and a voltage vector value of the motor;

determining a voltage adjustment value based on the voltage limit value and the voltage vector value;

superposing the voltage regulating value to an actual voltage value of the motor to obtain a de-rated voltage value;

and inquiring in the three-dimensional current lookup table based on the de-rated voltage value to obtain the current instruction value.

3. The method of claim 1, further comprising: and if the comparison result shows that the modulation coefficient is smaller than the first preset threshold value, the inverter continuously controls the motor to operate according to the current output current.

4. The method of claim 1, wherein the determining the derated torque of the electric machine based on the modulation factor comprises:

determining a derating coefficient of the motor based on the modulation coefficient;

and determining the derating torque of the motor according to the derating coefficient.

5. The method according to claim 1, wherein the controlling the inverter to output the corresponding current based on the queried current command value to control the motor derating operation comprises:

acquiring an actual three-phase current value of the motor, and converting the actual three-phase current value into an actual current value under a rotating coordinate system through coordinate conversion;

enabling the current instruction value to follow the current actual value under the rotating coordinate system, and obtaining a voltage reference value under the rotating coordinate system through a proportional-integral control operation method, wherein the voltage reference value comprises a direct-axis voltage reference value and a quadrature-axis voltage reference value;

converting the voltage reference value into a voltage reference value under a static coordinate system through coordinate transformation;

and determining the current value output by the inverter by adopting a pulse width modulation algorithm according to the voltage reference value in the static coordinate system so as to enable the inverter to control the motor to operate in a derating mode.

6. The method of claim 1, wherein prior to querying a three-dimensional current lookup table for a current command value based on the derated torque, the method further comprises: establishing a three-dimensional current table look-up through an experimental calibration method;

wherein, the establishing of the three-dimensional current table look-up table by the experimental calibration method comprises the following steps: establishing a non-flux weakening working condition current lookup table and a flux weakening working condition current lookup table by an experimental calibration method, and combining the non-flux weakening working condition current lookup table and the flux weakening working condition current lookup table to obtain the three-dimensional current lookup table.

7. The method of claim 6, wherein the establishing of the non-flux weakening condition current lookup table by the experimental calibration method specifically comprises the following steps:

setting a rotating speed, namely operating the permanent magnet synchronous motor at a preset rotating speed under a rated voltage;

setting parameters, namely setting current step length and setting different combinations of direct-axis current component instruction values and quadrature-axis current component instruction values;

traversing, namely traversing the states of all the motors in a current limit circle, and recording actual torques corresponding to different combinations of direct-axis current component instruction values and quadrature-axis current component instruction values;

a target value determining step, namely determining a direct-axis current component instruction value and a quadrature-axis current component instruction value which correspond to each actual torque and have the minimum current amplitude, and recording the direct-axis current component instruction values and the quadrature-axis current component instruction values as a target direct-axis current component instruction value and a target quadrature-axis current component instruction value to obtain the current lookup table under the non-flux weakening working condition;

and a first voltage setting step of setting different working voltages and repeatedly executing the motor setting step.

8. The method of claim 6, wherein the establishing of the weak magnetic operating condition current lookup table by the experimental calibration method specifically comprises the following steps:

step of determining step length, wherein the step length of the rotating speed of the motor is determined;

setting phase angles, namely setting different voltage phase angles at each rotating speed;

a table establishing step, namely recording the actual torque, the direct axis current component instruction value and the quadrature axis current component instruction value corresponding to each voltage phase angle to obtain the current table look-up under the flux weakening working condition;

and a second voltage setting step of setting different working voltages and repeatedly executing the step of determining the step length.

9. A derating control device for a permanent magnet synchronous motor, the derating control device comprising:

the comparison module is used for obtaining a modulation coefficient of the motor and comparing the modulation coefficient with a preset threshold value to obtain a comparison result, wherein the preset threshold value comprises a first preset threshold value and a second preset threshold value, and the first preset threshold value is smaller than the second preset threshold value;

the first determining module is used for determining derating torque of the motor based on the modulation coefficient if the comparison result shows that the modulation coefficient is larger than a first preset threshold and smaller than a second preset threshold;

the first query module is used for querying a three-dimensional current lookup table according to the derating torque to obtain a current instruction value, wherein the current instruction value comprises a direct-axis current component instruction value and a quadrature-axis current component instruction value, and the three-dimensional current lookup table is established by an experimental calibration method;

and the control module is used for controlling the inverter to output corresponding current based on the current instruction value obtained by inquiry so as to control the motor to derate.

10. A pm synchronous machine, characterized in that it uses a pm synchronous machine derating control method according to any one of the preceding claims 1-8.

Technical Field

The embodiment of the invention relates to the technical field of permanent magnet synchronous motor control, in particular to a derating control method and device for a permanent magnet synchronous motor and the permanent magnet synchronous motor.

Background

In order to alleviate the increasingly severe problems of environmental pollution and energy exhaustion, electric vehicles have been brought forward and have received extensive attention due to the characteristics of environmental protection, wherein, the permanent magnet synchronous motor replaces other motors to become the core component of the electric vehicle due to the advantages of good control performance, high power density and energy conservation, so that the research of a weak magnetic control strategy for ensuring that the permanent magnet synchronous motor is safe and reliable and operates in a wide rotating speed range has very important significance.

The back electromotive force of the permanent magnet synchronous motor is in direct proportion to the rotating speed and the flux linkage, the back electromotive force gradually reaches a basic speed point along with the increase of the rotating speed, and when the back electromotive force is larger than the maximum output voltage of the inverter, the inverter is saturated and out of control, and serious consequences are generated. The permanent magnet synchronous motor excitation magnetic field is generated by a permanent magnet, the magnetic field is constant and cannot be adjusted, and the purpose of weakening the flux and increasing the speed is achieved only by adjusting the stator current and increasing the direct axis current component of the stator to weaken the air gap magnetic field.

Disclosure of Invention

The invention provides a derating control method and device for a permanent magnet synchronous motor and the permanent magnet synchronous motor, which improve the reliability and stability of flux weakening control of the permanent magnet synchronous motor, avoid unexpected output or damage caused by saturation of an inverter for controlling the permanent magnet synchronous motor, and ensure that a vehicle can normally run under extremely low temperature working conditions, rapid acceleration and deceleration and severe road conditions.

The embodiment of the invention provides a derating control method for a permanent magnet synchronous motor, which comprises the following steps: obtaining a modulation coefficient of a motor, and comparing the modulation coefficient with a preset threshold to obtain a comparison result, wherein the preset threshold comprises a first preset threshold and a second preset threshold, and the first preset threshold is smaller than the second preset threshold; if the comparison result is that the modulation factor is larger than a first preset threshold and smaller than a second preset threshold, determining derating torque of the motor based on the modulation factor; inquiring in a three-dimensional current lookup table according to the derating torque to obtain a current instruction value, wherein the current instruction value comprises a direct-axis current component instruction value and a quadrature-axis current component instruction value, and the three-dimensional current lookup table is established by an experimental calibration method; and controlling the inverter to output corresponding current based on the current command value obtained by query so as to control the derating operation of the motor.

Further, before the controlling the inverter to output the corresponding current based on the queried current command value to control the derating operation of the motor, the method further includes: if the comparison result shows that the modulation coefficient is larger than a second preset threshold value, acquiring a voltage limit value and a voltage vector value of the motor; determining a voltage adjustment value based on the voltage limit value and the voltage vector value; superposing the voltage regulating value to an actual voltage value of the motor to obtain a de-rated voltage value; and inquiring in the three-dimensional current lookup table based on the de-rated voltage value to obtain the current instruction value.

Further, the method further comprises: and if the comparison result shows that the modulation coefficient is smaller than the first preset threshold value, the inverter continuously controls the motor to operate according to the current output current.

Further, the determining a derated torque of the electric machine based on the modulation factor comprises: determining a derating coefficient of the motor based on the modulation coefficient; and determining the derating torque of the motor according to the derating coefficient.

Further, the controlling the inverter to output a corresponding current based on the queried current command value to control the derating operation of the motor includes: acquiring an actual three-phase current value of the motor, and converting the actual three-phase current value into an actual current value under a rotating coordinate system through coordinate conversion; enabling the current instruction value to follow the current actual value under the rotating coordinate system, and obtaining a voltage reference value under the rotating coordinate system through a proportional-integral control operation method, wherein the voltage reference value comprises a direct-axis voltage reference value and a quadrature-axis voltage reference value; converting the voltage reference value into a voltage reference value under a static coordinate system through coordinate transformation; and determining the current value output by the inverter by adopting a pulse width modulation algorithm according to the voltage reference value in the static coordinate system so as to enable the inverter to control the motor to operate in a derating mode.

Further, before the current command value is obtained by querying a three-dimensional current lookup table according to the derated torque, the method further comprises the following steps: establishing a three-dimensional current table look-up through an experimental calibration method; wherein, the establishing of the three-dimensional current table look-up table by the experimental calibration method comprises the following steps: establishing a non-flux weakening working condition current lookup table and a flux weakening working condition current lookup table by an experimental calibration method, and combining the non-flux weakening working condition current lookup table and the flux weakening working condition current lookup table to obtain the three-dimensional current lookup table.

Further, the establishing of the non-flux weakening working condition current lookup table by the experimental calibration method specifically comprises the following steps: setting a rotating speed, namely operating the permanent magnet synchronous motor at a preset rotating speed under a rated voltage; setting parameters, namely setting current step length and setting different combinations of direct-axis current component instruction values and quadrature-axis current component instruction values; traversing, namely traversing the states of all the motors in a current limit circle, and recording actual torques corresponding to different combinations of direct-axis current component instruction values and quadrature-axis current component instruction values; a target value determining step, namely determining a direct-axis current component instruction value and a quadrature-axis current component instruction value which correspond to each actual torque and have the minimum current amplitude, and recording the direct-axis current component instruction values and the quadrature-axis current component instruction values as a target direct-axis current component instruction value and a target quadrature-axis current component instruction value to obtain the current lookup table under the non-flux weakening working condition; and a first voltage setting step of setting different working voltages and repeatedly executing the motor setting step.

Further, the establishing of the weak magnetic working condition current lookup table by the experimental calibration method specifically comprises the following steps: step of determining step length, wherein the step length of the rotating speed of the motor is determined; setting phase angles, namely setting different voltage phase angles at each rotating speed; a table establishing step, namely recording the actual torque, the direct axis current component instruction value and the quadrature axis current component instruction value corresponding to each voltage phase angle to obtain the current table look-up under the flux weakening working condition; and a second voltage setting step of setting different working voltages and repeatedly executing the step of determining the step length.

The embodiment of the invention also provides a derating control device of the permanent magnet synchronous motor, which comprises the following components: the comparison module is used for obtaining a modulation coefficient of the motor and comparing the modulation coefficient with a preset threshold value to obtain a comparison result, wherein the preset threshold value comprises a first preset threshold value and a second preset threshold value, and the first preset threshold value is smaller than the second preset threshold value; the first determining module is used for determining derating torque of the motor based on the modulation coefficient if the comparison result shows that the modulation coefficient is larger than a first preset threshold and smaller than a second preset threshold; the first query module is used for querying a three-dimensional current lookup table according to the derating torque to obtain a current instruction value, wherein the current instruction value comprises a direct-axis current component instruction value and a quadrature-axis current component instruction value, and the three-dimensional current lookup table is established by an experimental calibration method; and the control module is used for controlling the inverter to output corresponding current based on the current instruction value obtained by inquiry so as to control the motor to derate.

The embodiment of the invention also provides a permanent magnet synchronous motor, and the permanent magnet synchronous motor uses the derating control method of the permanent magnet synchronous motor in any embodiment.

The invention discloses a derating control method and device for a permanent magnet synchronous motor and the permanent magnet synchronous motor, wherein the method comprises the following steps: acquiring a modulation coefficient of the motor, and comparing the modulation coefficient with a preset threshold value to obtain a comparison result; if the comparison result is that the modulation factor is larger than a first preset threshold and smaller than a second preset threshold, determining derating torque of the motor based on the modulation factor; inquiring in a three-dimensional current lookup table according to the derating torque to obtain a current instruction value; and controlling the inverter to output corresponding current based on the inquired current command value so as to control the derating operation of the motor. The invention solves the technical problem that the current fluctuation generated by directly superposing the output result of the controller to the direct axis current influences the control effect of the motor in the prior art, improves the reliability and the stability of the flux weakening control of the permanent magnet synchronous motor, avoids unexpected output or damage caused by saturation of an inverter controlling the permanent magnet synchronous motor, and ensures that the vehicle can normally run under extremely low temperature working conditions, rapid acceleration and deceleration and severe road conditions.

Drawings

Fig. 1 is a flowchart of a derating control method for a permanent magnet synchronous motor according to an embodiment of the present invention;

FIG. 2 is a block diagram of an extrinsic derate control strategy provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of voltage vectors under different modulation strategies provided by an embodiment of the present invention;

FIG. 4 is a block diagram of a voltage difference feedback derating control strategy according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of modulation factors under an extrinsic derating control strategy according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a current limit circle and a voltage control ellipse provided by an embodiment of the present invention;

fig. 7 is a structural diagram of a derating control device of a permanent magnet synchronous motor according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

It should be noted that the terms "first", "second", and the like in the description and claims of the present invention and the accompanying drawings are used for distinguishing different objects, and are not used for limiting a specific order. The following embodiments of the present invention may be implemented individually, or in combination with each other, and the embodiments of the present invention are not limited in this respect.