Extension of the Stray Voltage Capture Short-Circuit Detection Method to a 6-Phase Fault-Tolerant Dual-Motor Drive

Abstract

This paper investigates and validates the applicability of the recently developed stray voltage capture (SVC) ultra-fast short-circuit (SC) detection method and its extended version (ESVC) to fault-tolerant multi-motor drives. As these methods are system-based, a fault localization algorithm is also developed. Simulation analysis of the inverter stray inductances shows additional challenges for the SVC method making it hard to achieve ultra-fast SC detection. The ESVC method is slower but overcomes these challenges. The methods are adapted for a 400 V 6-phase Silicon Carbide based inverter equipped with a 2-level turn-Off hardware protection scheme. Fault under load and hard switching fault tests are performed showing the effectiveness of the ESVC in fast (smaller than 330 ns) and reliable SC detection and protection for SiC MOSFETs. The fault localization algorithm is also validated showing a localization speed smaller than 20 µs.