A Non-contact 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 paper proposes a rapid, non-contact method for detecting open-circuit faults (OCFs) in VSI systems. The high-frequency common-mode (HFCM) switching oscillation current is non-invasively 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-triggered OCF detection system has been developed, which consists of an 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.