Open-Circuit Fault Diagnosis Method for Inverters Based on Common Characteristics in Critical Region

Open-circuit fault of power switch is one of the common fault types in motor drive system. Diagnosing open-circuit fault accurately and quickly is very important. The regulation by controller often impairs the regularity of faulty current characteristics. The multipossibility of the control parameters will weaken the generalization ability for some fault diagnosis methods, which means that the accuracy of the diagnostic method is reduced. In this article, the concept of critical characteristics (CC) is proposed for the first time, which provides the theoretical basis for extracting characteristic and setting criterion in facing multipossibility disturbance factors. Then, the average value of three-phase current absolute value is used as CC for diagnosing open-circuit fault of inverter. Finally, experimental results show that the proposed method has strong generalization ability for different control parameters, low sensitivity for noise and various load, and high diagnostic speed.