IEEE Workshop on Wide Bandgap Power Devices and Applications in Asia (WiPDA Asia 2018)

344 / 2017-12-09 00:40:42

Power Loss Analysis of a Novel Modular Multilevel Converter Based on Semi-full-bridge Sub-module with SiC-MOSFET Switched Capacitors

MMC,SiC MOSFET,power losses

Plenary track > Applications in renewable energy and storage, transportation, industrial drives, and grid power

This paper presents a novel modular multilevel converter (MMC) whose sub-module (SM) is of semi-full bridge structure with SiC-MOSFET switched capacitors. Compared with conventional half- and full-bridge (H&FB) hybrid MMC, the proposed capacitor-switching semi-full-bridge (CS-SFB) MMC has the same DC fault ride through (FRT) capability due to the unchanged positive and negative output voltage levels. Moreover, thanks to the SFB structure, the currents of some Si-IGBTs are half of the arm current, thus the conduction losses are reduced. And because the SiC-MOSFETs in series with DC-link capacitors switch faster than Si-IGBTs, zero voltage switching (ZVS) and zero current switching (ZCS) can be realized for some Si-IGBTs, implying that the switching losses can be reduced simultaneously. The calculation results based on the verification model show that the conduction, switching and total power losses for the proposed CS-SFB SM can be reduced 20%, 26% and 22% respectively, compared with H&FB SM.