Real-Time Diagnosis of Open Circuit Faults in Three-Phase Voltage Source Inverters

This article investigates the real-time diagnosis of single and double open circuit faults (OCFs) in three-phase voltage source inverters (VSIs). The method analyzes the phase current waveforms continuously in real-time, and abnormal patterns of the current waves due to the corresponding switch OCFs are extracted to define as the fault detection waveforms (FDW). The current values of the FDWs are analyzed and a new scheme is developed to distinguish current waveform patterns from those of normal to unbalanced loads situations and switch OCFs. The scheme detects the starting zero crossing point first and then checks the magnitudes of the FDW. Periodic detections are applied to identify whether the collected data samples are within the FDW current range. The OCFs of the inverter switches are identified by counting the fault points within the predicted samplings of FDWs. The method has been verified through both simulations and experiments. The results confirm the effectiveness of the proposed scheme.