300W 175○C Half Bridge Power Building Block with High Temperature SiC MOSFETs for Harsh Environment Applications

A 300W 175°C half bridge power building block with SiC MOSFETs is investigated for high temperature harsh environment applications in this paper. The switching energy of 1.2kV HT SiC MOSFET CHT-NEPTUNE with TO-257 package and 225°C junction temperature from Cissoid are characterized at both room temperature and high temperature. 650V SiC diode 1N8032 with TO-257 package and 250°C junction temperature from GeneSiC is used as the freewheeling diode for double pulse switching test. The turn-on loss of HT SiC MOSFET is larger than the turn-off loss. The turn-on loss gets lower when the junction temperature increase, and the turn-off loss gets higher when the junction temperature increase. A half bridge power building block prototype is built in lab to verify the power capability and circuit functionality at 175°C high temperature. The power loss and temperature rise of SiC MOSFET are comparative studied at different switching frequency for the half bridge power building block. Higher switching frequency will lead to significant temperature rise for SiC MOSFET from 20kHz to 50kHz at 175°C high temperature. The temperature rise of the SiC MOSFET and the volume of passive components which can be minimized with increased frequency need to be optimal trade-off at high temperature.