High Power Density Submodule Development for a 20 kV T-Type Modular Dc Circuit Breaker with a 3.3 kV SiC Power Module

The medium-voltage (MV) silicon-carbide (SiC) power module enhances the competitiveness of the solid-state DC circuit breaker by improving both efficiency and power density and reducing the maintenance cost. This paper presents the design, analysis, and validation of a high power density submodule for a 20 kV, 50 A SiC-based T-type modular dc circuit breaker. To realize high power density and high current capability for medium voltage applications, a novel PCB-based busbar with 14.3-oz copper layers is designed. The gate drive circuit implements a special power architecture and a discrete transformer to achieve high common mode transient immunity and high insulation voltage. The interconnection stray inductance from the submodule assembly is also evaluated and it will only bring negligible voltage overshoot during the breaking condition. A power density of 192.25 kW/L of the submodule is achieved and all the results validate the proper operation of the submodule as a building block in a circuit breaker.