Hardware Design of Medium Voltage SiC-based Modular Multilevel Converters for Grid-tied Applications

• Published in: 2021 IEEE 8th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) pp. 339 - 344
• Main Authors: Wang, Ke, Ma, Dihao, Hu, Boxue, Wang, Jin, Singh, Akanksha, Mather, Barry
• Format: Conference Proceeding
• Language: English
• Published: IEEE 07-11-2021
• Subjects: auxiliary power supply; busbar; Electric potential; gate driver; Insulation; modular multilevel converter; MOSFET; Multilevel converters; Partial discharges; Power supplies; SiC MOSFET; Silicon carbide
• DOI: 10.1109/WiPDA49284.2021.9645106

This paper presents a design of a 10 kV silicon carbide (SiC) MOSFET based modular multilevel converter (MMC). The MMC functions as the interconnection between a 24 kV dc bus and a 13. SkV distribution grid. This paper focuses on the hardware design of the MMC and its submodules. The gate driver, auxiliary power supply and bus bur in submodules are major components that need to meet high dv/dt immunity and high insulation voltage requirements. The gate driver achieves over 200 kV/\mus common mode transient immunity (CMTI). Its associated auxiliary power supply is based on an on-board transformer with over 30 kV insulation capability and 1.4 pF barrier capacitance. The busbar achieves less than 11 kV/cm electric field in the air to avoid partial discharges. Validation tests of the MMC submodule were performed by double pulse tests at 5 kV and buck converter tests at3 kV, 52A (peak). Reliable operations were achieved in validation tests.