Junction temperature estimation and protection scheme for SiC MOSFET devices

A scheme of thermal estimation is proposed for SiC power MOSFET devices and applied in overcurrent fault protection. Initial junction temperature before fault occurrence is estimated by finding the instantaneous on-state resistance which is temperature sensitive and can be used as an indicator for device junction temperature estimation. Based on the scheme, a circuit is designed to detect the on-state resistance and estimate the corresponding internal temperature of the SiC MOSFET. This estimation circuit provides temperature information to protection circuit for interrupting overcurrent within allowable time. The scheme is tested on the SiC power MOSFET C2M0080120D with the laboratory measurement results verified.