Research On On-line Diagnosis Method Of Open Circuit Fault Of Inverter In Motor Drive System

In recent years,with the advent of the "motor era",from aerospace and national defense security,to daily production and life,are increasingly inseparable from the motor drive system,its importance is self-evident,and the safety of the motor drive system has become the focus of people's attention.Because of the vulnerability and complexity of the main circuit power devices in the motor driver,the inverter becomes a high-risk component in the motor drive system,whose reliability directly affects the safety and stability of the whole system.The working principle and working mode of the inverter determine that the main circuit power tube needs to be switched frequently,which greatly increases the probability of open circuit fault of the inverter,so it is very necessary to study the open circuit fault of the main circuit power tube of the inverter.In this paper,the open circuit fault diagnosis method of inverter power tube in motor drive system is studied and analyzed.(1)In view of the shortcomings of the existing expert system detection method,the huge system knowledge base is difficult to improve,and the voltage detection method needs to add additional hardware detection circuit,this paper proposes to use the three-phase current signal of the motor drive system as the main variable for the inverter open circuit fault diagnosis.Based on the simulation model of permanent magnet synchronous motor(PMSM),the characteristics of the current changes before and after the open circuit faults of different power tubes of the inverter are analyzed,The inverter open circuit faults are divided into five categories and 27 kinds.(2)In order to reduce the influence of the dynamic operation of the motor drive system on the stability of the open circuit fault detection method,an open circuit fault diagnosis method based on the three-phase current of the motor drive system is proposed in this paper The open circuit fault diagnosis of all kinds of inverters can be completed after variable weighting.The simulation model is built in the Simulink environment.The simulation results show that the method can detect and locate all kinds of open circuit fault of inverter only by collecting the three-phase current of the motor drive system as the input signal,and the sudden change of speed and load will not lead to misdiagnosis.(3)The open circuit fault diagnosis test platform of the motor drive system inverter is constructed.The PWM signal transmission line of the inverter is set with switches on the experimental platform to simulate the open circuit fault of the inverter,and the fault diagnosis method proposed in this paper is tested.The results show that the proposed diagnosis method candetect and locate 27 kinds of open circuit faults in five categories of inverter power transistor,and will not cause misdiagnosis when the sensitive parameters of motor operation such as speed and load mutation.