A Single Gate Driver-based Four-stage High-voltage SiC Switch Having Dynamic Voltage Balancing Capability

A wide range of pulsed power applications require controllable switches with features such as high-voltage (HV) blocking and high-current carrying capacity especially at high repetition rates. As of now, the voltage blocking ability of a single commercial off-the-shelf (COTS) SiC MOSFET is limited to 3.3 kV [1]. Stacking multiple switches in series can increase the voltage blocking ability although it comes with voltage balancing issues during steady-state and switching transitions. In order to overcome limitations such as moderate switching speed and low voltage blocking ability of existing COTS switches, we have designed a four-stage 4.8 kV HV switch with a new voltage balancing technique, which involves the use of a single gate driver and this architecture is built using four (4) 1.2 kV SiC MOSFETs. The voltage balancing across these four MOSFETs has been tested using a resistive load at a maximum switching frequency of 40 kHz and a supply voltage up to 2.5 kV, although the switching frequency can be pushed beyond 100 kHz, The switch exhibits excellent steady-state and dynamic state voltage balancing performance in addition to minimal ringing in gate-source and drain-source voltages across all MOSFETs in the series stack. In addition, we have designed and developed a four-stage 6.8 kV rated HV switch using four (4) 1. 7 kV SiC MOSFETs adopting a similar voltage balancing technique, and the switch has been tested up to a supply voltage of 4 kV and at a switching frequency up to 20 kHz.