Unified Switching Loss Comparison Method for SiC MOSFETs in Electric Vehicle Traction Inverters

For future high-power Electrical Vehicles (EVs), the traditional 400V battery system will be replaced by 800V battery system. 1200V SiC MOSFETs may dominate the future high-voltage high-power EV traction inverters. Comparing different SiC devices and selecting suitable devices for EV traction inverter design are becoming very critical. Since the current EV motors are designed based on IGBT inverters, the dv/dt must be limited to under 15V/ns, even 10V/ns or 6V/ns. However, the traditional device comparison methods don't consider this extremely important limitation. This paper proposes a unified switching loss comparison method for SiC MOSFETs in EV traction inverters. In this method, the switching loss of different devices will be evaluated under the same dv/dt. This paper provides a detailed loss model based on this method. We find out that the switching turn on loss depends on the ratio of Q <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</inf> /Q <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</inf> under the same dv/dt condition. Using this method, we evaluate and compare the switching turn on losses of some 1.2kV SiC MOSFETs from different vendors with different technologies under the same DC link voltage and switching current.