EP-4138297-B1 - DIRECT TORQUE CONTROL METHOD AND APPARATUS FOR ALTERNATING CURRENT MOTOR, AND RELATED COMPONENTS

EP4138297B1EP 4138297 B1EP4138297 B1EP 4138297B1EP-4138297-B1

Inventors

FENG, Jianghua
YANG, FAN
WEN, YULIANG
MEI, Wenqing
ZENG, Xiaofan
LI, CHENG
HUANG, Jiade
ZHENG, HANFENG
ZHANG, Zhaoyang
LIAN, Guoyi

Dates

Publication Date: 20260506
Application Date: 20200826

Claims (12)

A method for direct torque control of an alternating current motor, comprising: obtaining an actual position, of a stator flux linkage of the alternating current motor, on a fixed polygonal stator flux linkage trajectory; and performing single-boundary hysteresis comparison processing, wherein the single-boundary hysteresis comparison processing comprises: outputting a pulse signal corresponding to a zero vector to control an inverter, and obtaining a feedback torque of the alternating current motor, wherein the actual position is coincident with a preset position on a side of the fixed polygonal stator flux linkage trajectory, wherein preset positions on individual sides of the fixed polygonal stator flux linkage trajectory are located as the same as each other; determining whether the feedback torque satisfies a preset condition corresponding to the single-boundary hysteresis comparison; and determining a present effective voltage vector based on the actual position, and outputting a pulse signal corresponding to the present effective voltage vector to control the inverter, on determining that the feedback torque satisfies the preset condition.
The method according to claim 1, wherein the obtaining an actual position, of a stator flux linkage of the alternating current motor, on a fixed polygonal stator flux linkage trajectory comprises: obtaining the actual position of the stator flux linkage of the alternating current motor on the fixed polygonal stator flux linkage trajectory through a motor model observer; and the obtaining a feedback torque of the alternating current motor comprises: obtaining the feedback torque of the alternating current motor through the motor model observer.
The method according to claim 1, wherein the preset position is set to be a midpoint position on the side of the fixed polygonal stator flux linkage trajectory.
The method according to claim 1, wherein the preset position is set to be one of positions that are on the side of the fixed polygonal stator flux linkage trajectory and are symmetrical with respect to a midpoint on the side.
The method according to claim 1, further comprising: not determining whether the feedback torque satisfies the preset condition, in a case that the pulse signal corresponding to the present effective voltage vector is outputted to control the inverter.
The method according to claim 1, further comprising: determining whether a rotation direction of the alternating current motor is a forward direction or a backward direction; and determining the preset condition based on the rotation direction.
The method according to claim 6, wherein the preset condition comprises that: the feedback torque is less than a lower boundary of a given hysteresis loop, on determining that the alternating current motor is rotated in the forward direction.
The method according to claim 6, wherein the preset condition comprises that: the feedback torque is greater than an upper boundary of a given hysteresis loop, on determining that the alternating current motor is rotated in the backward direction.
The method according to claim 7, further comprising: calculating a target value based on a maximum torque and a minimum torque of the alternating current motor, wherein the target value is equal to half of a difference between the maximum torque and the minimum torque; and obtaining the lower boundary of the given hysteresis loop by calculating a difference between a given torque and the target value.
An apparatus for direct torque control of an alternating current motor, comprising: an obtaining module, configured to obtain an actual position, of a stator flux linkage of the alternating current motor, on a fixed polygonal stator flux linkage trajectory; a first processing module, configured to perform single-boundary hysteresis comparison processing, wherein the single-boundary hysteresis comparison processing comprises: outputting a pulse signal corresponding to a zero vector to control an inverter, and obtaining a feedback torque of the alternating current motor, wherein the actual position is coincident with a preset position on a side of the fixed polygonal stator flux linkage trajectory, wherein preset positions on individual sides of the fixed polygonal stator flux linkage trajectory are located as the same as each other; a determination module, configured to determine whether the feedback torque satisfies a preset condition corresponding to the single-boundary hysteresis comparison; and trigger a second processing module on determining that the feedback torque satisfies the preset condition; and the second processing module, configured to determine a present effective voltage vector based on the actual position, and output a pulse signal corresponding to the present effective voltage vector to control the inverter.
An electronic device, comprising: a memory storing a computer program; and a processor, configured to execute the computer program and implement the method according to any one of claims 1 to 9.
A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the method according to any one of claims 1 to 9.

Description

FIELD The present disclosure relates to the field of control of an alternating current motor, and in particular to a method and an apparatus for direct torque control of an alternating current motor, and related components. BACKGROUND In the field of alternating current drive, conventional control methods include vector control and direct torque control. The vector control adopts an idea of decoupling control, by which a three-phase current of a motor is transformed into a direct current in a synchronous rotating coordinate system for a closed-loop control. The vector control is to continuously control a system, and has better dynamic and static performance under a medium/high switching frequency, but has a poor dynamic performance under a low switching frequency. The direct torque control adopts an instantaneous voltage vector theory, rather than the decoupling control. A control based on a hysteresis comparison with an upper or lower boundary is directly performed in a stator coordinate system, in order to control a torque and a flux linkage within a certain tolerance range. Such control system has a rapid torque response without overshoot, and therefore is an alternating current speed regulation method with high dynamic and static performances. With the conventional direct torque control, a stator flux linkage may be controlled to travel on a fixed polygonal flux linkage trajectory, such as an octadecagon flux linkage trajectory or a hexagonal flux linkage trajectory. In this case, the torque is controlled within a certain tolerance range by a comparison with the upper or lower boundary of a hysteresis loop. The tolerance range is regulated by a switching frequency regulator. However, such solution has a problem that a switching frequency is not fixed and a current harmonic content is relatively large, which limits an application scope of the solution to a certain extent. The patent CN110971168A provides an improved induction motor model prediction direct torque control method. According to the method, three voltage vectors to be predicted are screened out from eight voltage vectors through a switch table; and then two-step flux linkage prediction and one-step torque prediction are carried out on the basis of delay compensation, torque variations corresponding to the three voltage vectors in the first-step torque prediction are calculated respectively, the second-step torque prediction is completed according to the torque variations, and finally, the voltage vector capable of minimizing the cost function is selected to act on the inverter. The document XP55902886 provides a vector control strategy of permanent magnet synchronous motor based on optimal stator flux trajectory closed-loop control. The principle of harmonic current minimum optimization PWM was briefly described, the optimal switching angle was provided, and the mathematical relationship between the optimal switching angle and the corresponding optimal flux trajectory was established. Based on the hybrid modulation strategy including asynchronous modulation and synchronous modulation, the vector control system of PMSM's maximum torque-current ratio was constructed. Therefore, how to provide a solution that can solve the above technical problem is a problem needed to be solved by those skilled in the art at present. SUMMARY An objective of the present disclosure is to provide a method and an apparatus for direct torque control of an alternating current motor, an electronic device and a computer-readable storage medium, with which requirements for a three-phase symmetry, half-wave symmetry and quarter-symmetry of an output voltage can be satisfied, harmonics of the output voltage can be reduced, the direct torque control can be realized at a fixed switching frequency, a pulse output can be optimized, and a wide application range is realized. In order to solve the above technical problem, a method for direct torque control of an alternating current motor is provided in an embodiment of the present disclosure. The method includes: obtaining an actual position, of a stator flux linkage of the alternating current motor, on a fixed polygonal stator flux linkage trajectory; and performing single-boundary hysteresis comparison processing, where the single-boundary hysteresis comparison processing includes: outputting a pulse signal corresponding to a zero vector to control an inverter, and obtaining a feedback torque of the alternating current motor, in a case that the actual position is coincident with a preset position on a side of the fixed polygonal stator flux linkage trajectory, where preset positions on individual sides of the fixed polygonal stator flux linkage trajectory are located as the same as each other; determining whether the feedback torque satisfies a preset condition; and determining a present effective voltage vector based on the actual position, and outputting a pulse signal corresponding to the present effective voltage vector to