Asynchronous motor direct torque control system and method regulating duty cycle based on rotating speed

Abstract

The invention discloses an asynchronous motor direct torque control system and method regulating duty cycle based on rotating speed. The system comprises a motor state observation module, a voltage vector generation module, and a motor control module. The method comprises steps that the motor state observation module collects motor rotating speed, and instantaneous phase voltage and phase currentof a stator winding, and calculates electromagnetic torque, stator flux linkage amplitude and information of a sector in which the stator flux linkage is; the voltage vector generation module calculates offset of the stator flux linkage amplitude and offset of the electromagnetic torque by combining output of a rotating speed regulator and a set stator flux linkage amplitude of the system according to motor state information, generates a control signal through a torque controller and a flux controller, sends the control signal to a voltage vector selection table, selects a voltage vector and determines voltage vector action time; and the motor control module generates a drive signal according to the voltage vector and duty cycle information, so as to drive the motor to run. The asynchronous motor direct torque control system has a simple structure, torque response is fast, torque ripple of the motor is lowered, and running performance of the motor is improved.

Description

technical field [0001] The invention relates to the technical field of direct torque control of asynchronous motors, in particular to a system and method for direct torque control of asynchronous motors based on rotational speed adjustment duty cycle. Background technique [0002] The direct torque control technology of asynchronous motor abandons the idea of ​​decoupling in vector control. Its basic idea is to sample the three-phase voltage and current of the stator in real time, and calculate the error of the stator flux linkage and electromagnetic torque and the position of the stator flux linkage. , using a hysteresis comparator and a voltage vector selection table to generate a suitable voltage vector to apply to the asynchronous motor, and finally realize the direct control of the electromagnetic torque. This technology has the advantages of simple structure and less dependence on motor parameters, but its disadvantages are asymmetrical flux linkage control, large curr...

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Problems solved by technology

This technology has the advantages of simple structure and little dependence on motor parameters, but its disadvantages are asymmetrical flux linkage control, large current and torque ripple, etc.

[0003] In order to overcome the shortcomings of the traditional direct torque control technology, many methods have been proposed in the industry, such as the use of space vector modulation technology, fuzzy logic adaptive method to obtain the duty cycle, and the method of making the average torque approach the reference torque in one cycle , but the algorithms of these methods are complex and depend on multiple motor parameters

Li Zhengxue proposed a simple duty cycle determination method based on torque error and flux linkage error to reduce torque ripple, but did not consider the influence of motor speed, resulting in a large steady-state error of torque, so the motor cannot be accurately and effectively controlled

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