A Multilevel-Modular 10 kV Silicon Carbide MOSFET Module using Custom High-Voltage Isolated Gate Driver, Coupling, and Snubber Circuits

This paper presents a multilevel-modular high voltage (HV) switch architecture comprised of series-connected SiC MOSFETs and a voltage balancing method that achieves <1.1% voltage mismatch under steady-state and switching modes. An individual module consists of four series-connected 1.7-kV rated SiC MOSFETs, yielding a breakdown voltage of 6.8-kV, and driven by a single custom 10-kV isolated gate driver. One gate driver per module and 46 passive components (e.g., coupling capacitors, resistors, etc.) per module lead to low-cost fabrication and simpler operation of this HV switch. The unique modularity feature of the proposed switch enables voltage scalability to the limit of the weakest passive link. Any single or a combination of multiple passive components (e.g., capacitors, diodes, resistors, etc.) can form the weakest passive link in a module. Further, the high volumetric power density realized by the physical layout and modular stacking is within 80% of a fully custom/integral design. The working principle of the HV switch during switching transients and steady-state are demonstrated and compared in simulation and from measurements. Simulation and experimental results demonstrate excellent voltage balancing as supported by a minimal voltage imbalance of <80-V among the individual MOSFETs in the HV switch at a supply voltage of 6-kV and a switching frequency of 15-kHz.