A Hybrid Current and Voltage-Source Gate Driver for Series-Connected SiC MOSFETs

The series-connection of Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) is an attractive way of increasing the blocking voltage capability of a switch. However, due to inherent transient and steady-state voltage imbalance issues, such a design imposes challenges, especially at elevated switching frequencies, where increased dv/dt is required. This paper proposes a hybrid gate driver for series-connected SiC MOSFETs, which consists of a turn-on stage with a traditional Voltage Source Gate Driver (VSGD), and a turn-off sequence with a Current Source Gate Driver (CSGD). The proposed hybrid gate driver has been validated experimentally in two series-connected SiC MOSFETs. Experimental results show voltage balancing within 2% of the total voltage and switching speeds towards 70 kV/μs.