Switching Cell Design for Medium Voltage Flying Capacitor Converter with 10 kV SiC MOSFET

This paper presents the switching cell design for medium voltage (MV) flying capacitor converter (FCC) with emerging 10 kV SiC MOSFET using a 5-level FCC for the 13.8 kV MV grid as an example. The design of flying capacitors and decoupling capacitors to achieve compact size, loop inductance minimization, high voltage insulation, and good scalability is discussed. The flying capacitor switching cell double pulse test (FCC-DPT) concept is proposed for switching evaluation. With detailed switching loop characterization and analysis, the switching speed of this 10 kV 20 A SiC MOSFET discrete device is pushed to exceed 100 V/ns. Hardware of the 5L-FCC phaseleg is built and continuous power test experimental results up to 23 kV dc voltage are demonstrated.