QCM-Enabled SiC Three-Phase Traction Inverter

This article proposes a quadrilateral current mode (QCM) soft-switching scheme for three-phase traction inverters with multiple SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs) in parallel. A phase-shift modulation scheme is applied to inductor-decoupled parallel half-bridge legs, generating a circulating current flowing through these commutation inductors. Thus, the current of each half-bridge leg is reshaped as quadrilaterals, which enables all the parallel MOSFETs to achieve zero-voltage switching (ZVS). The switching losses of the 650-V STPAK™ SiC MOSFET at different junction temperatures are characterized with double-pulse tests. Then the operation principle and characteristics of QCM are detailed. Finally, a QCM-enabled three-phase traction inverter using the STPAK SiC MOSFETs is developed and tested to verify the advantages of QCM operation in power loss reduction and efficiency improvement.