A Noncontact Open-Circuit Fault Detection Method for VSI Systems Using High-Frequency Common-Mode Switching Oscillations

Fault diagnosis is essential for enhancing the reliability of voltage source inverter (VSI) systems. This article proposes a rapid, noncontact method for detecting open-circuit faults (OCFs) in VSI systems. The high-frequency common-mode (HFCM) switching oscillation current is noninvasively captured as a novel indicator. The integrity of the HFCM oscillation signal is utilized to detect and locate the faulty power devices in the VSI system. An HFCM switching oscillation event (SOE)-triggered OCF detection system has been developed, which consists of a high-frequency (HF) switching oscillation sensor, switching event capture circuit, and OCF detection and diagnostic unit. Experimental validation confirms the method’s rapid OCF detection capability within a single switching cycle and its robustness across various operating conditions. Furthermore, this approach enables OCF detection for all six power devices in a VSI system using a single diagnostic variable, i.e., the HFCM switching oscillation current.