Research on fault-tolerant operation strategy of rectifier of square wave motor in wind power system

In wind power system, the randomness of wind energy increases the probability of components fault. once the switch fault of the PWM rectifier is detected, it will lead to the distortion of the motor voltage and current waveform, the increase of torque ripple, the fluctuation of filter capacitor voltage, and the increase of harmonic content, which will affect the control performance and operation safety of the system. A common fault in a three-phase PWM rectifier is the open-circuit fault of the switch. This paper analyzes the current waveform distortion of the square wave motor when the rectifier switch fault, and proposes different fault-tolerant control strategies for different situations of switch fault, include single, double and triple switches fault. This method is based on several special driving modes under power generation situation of square wave motor. The strategy is easy to implement and does not need to change the circuit topology. It can realize fault-tolerant control of switch faults in the same side half bridge or the same bridge arm of the three-phase PWM rectifier. The effectiveness of the proposed fault-tolerant strategy is verified by simulation and experiment at the end of the article.