Fault Detection of 3-Phase VSI using Wavelet-Fuzzy Algorithm

The good knowledge and information about the fault mode behaviour of the PWM voltage source inverter is important to improve system design, protection and fault tolerant control. This paper develops a real-time condition-monitoring algorithm for 3-phase Pulse Width Modulation (PWM) inverter in fuzzy speed controlled induction machine. It is designed to detect and identify the transistor open-circuit fault and an intermittent misfiring fault, which commonly occurs in the inverter drive system. The condition monitoring mechanism is based on Discrete Wavelet Transform (DWT) and Fuzzy Logic (FL). In this method, the stator currents are used as an input to the system. No direct access to the induction motor is required. The developed system has been rigorously assessed theoretically and experimentally, and it has been shown that the system is robust and reliable.