New 40kV / 300kVA Quasi-2-Level Operated 5-Level Flying Capacitor SiC “Super-Switch” IPM

Abstract

Emerging applications, e.g., traction systems and utility scale renewable energy systems, demand for Medium Voltage (MV)power electronic switches with blocking capabilities above 20kV, which cannot be provided with today's 10kV or 15kV SiC power semiconductors. Therefore, this work investigates different concepts for the realization of a MV half-bridge, i.e., a series connection of 10kV SiC MOSFETs, a JFET Super Cascode arrangement, and Modular Multilevel Converter (MMCs)and Flying Capacitor Converter (FCCs)topologies. The FCC topology features several advantages such as reduced switching losses, reduced chip area, lower dv/dt of the switching transitions, and robust voltage balancing. Moreover, the volume of the flying capacitors can be reduced with Quasi-2-Level (Q2L) operation of the half-bridge, where the intermediate voltage levels are only used during very short time intervals, i.e., during the switching transitions. This paper analyzes the design, the switching behavior, and the voltage balancing of the Q2L-FCC bridge-leg and confirms its suitability as a versatile MV switch. Finally, the integration of a complete bridge-leg, including gate drivers, isolated cooling interfaces, measurements, and Q2L control into a 300 kVA/40 kV SiC Super-Switch Intelligent Power Module (SiC-SS-IPM)is presented.