An Enhanced Over-Current Fault Detection System for a 7.2kV Power Module Using Series-Connected SiC MOSFETs

This paper presents a high-speed overcurrent protection system for a 7.2kV power module using series-connected SiC MOSFETs. The system integrates a tunnel magneto-resistance (TMR) current sensor for non-invasive current measurement and an optical splitter. In the event of over-current, the central controller sends the shutdown signal to each series-connected SiC MOSFET simultaneously through the 1-to-6 optical splitter. Through finite element analysis (FEA), the TMR sensor placement is optimized to mitigate skin-effect-induced measurement errors, achieving a current detection delay of 30 ns. The optical splitter enables simultaneous shutdown commands to six sub-modules with 33 ns latency and 230ps inter-module deviation. Testing this prototype on a half-bridge arm demonstrated short-circuit protection within 81.6 ns, demonstrating the system's capability to enhance reliability for the 7.2kV SiC power module.