Variable switching frequency PWM torque ripple control method for alternating-current motor

Abstract

The present invention discloses a variable switching frequency PWM torque ripple control method for an alternating-current motor. A system mainly comprises a torque ripple prediction module and a switching cycle updating module. According to the method of the invention, with a PWM torque ripple peak value adopted as a control object, a PWM torque ripple prediction algorithm is established based on a two-level current ripple real-time prediction model; and with the PWM torque ripple peak value adopted as the control object, the algorithm can be adopted to change the switching frequency of a two-level voltage source inverter. Compared with constant switching frequency PWM control (CSFPWM), the variable switching frequency PWM control (VSFPWM) can effectively reduce the average switching frequency of the inverter, thereby, reducing switching loss, and at the same time, the variable switching frequency PWM control (VSFPWM) can effectively improve the EMI noises of a motor driving system.

Description

technical field [0001] The invention belongs to the field of voltage source variable switching frequency, and more specifically relates to a two-level voltage source variable switching frequency based on a PWM torque ripple real-time prediction model. Background technique [0002] In modern AC motor drive systems, torque ripple is an important parameter to measure the entire system. Torque ripple will bring vibration, hearing and other noise to the motor system. In many applications, it is directly related to the operating quality of the entire system. [0003] The generation of motor torque ripple mainly comes from two aspects. First, in the process of motor design, the motor torque ripple is directly related to the structure of the motor. This part of the torque ripple is mainly related to the fundamental frequency of the back EMF and its harmonics. Second, because the inverter is not an ideal sinusoidal power supply, but uses a series of PWM waves to simulate the required...

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Problems solved by technology

[0004] At present, many achievements have been made for PWM torque ripple. The existing methods mainly propose some model predictive motor control algorithms, but the above model predictive motor control algorithms are more complicated than traditional motor vector control.

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