A 1200V/425A SiC MOSFET Power Module with Integrated Balancing Circuit For Series-connection Applications

Voltage source converters (VSCs) based on series-connected power devices can have smaller size compared to modular multilevel converters. Voltage of series-connected SiC MOSFETs can be balanced using the active clamping module (ACM). This work packages the main SiC MOSFET and the auxiliary switch in ACM as a power module, which will minimize the parasitic inductance of the ACM loop to suppress the voltage spikes when power devices turn off in the medium voltage VSC. A 1.2kV/425A SiC power module with an integrated ACM auxiliary switch is designed to ensure effective current sharing and minimal parasitic inductance. A single-phase back-to-back prototype is constructed, each arm consists of two designed modules. Experimental results show that under the condition of 100V/50A, the voltage overshoot is reduced from 215V to 13V, showing a 94% voltage spike reduction. Under 600A/300A conditions, the voltage of series-connected SiC MOSFET modules are well balanced, with the voltage overshoot of only 84V despite a DC loop inductance over 500nH.