In Situ Conduction Current Extraction of SiC MOSFET Modules in Switching Transient Based on Second-Order Passive Filtering

The conduction current of power semiconductor devices serves as a necessary reference value for switching trajectory optimization, junction temperature monitoring, and aging assessment functions of intelligent active gate drives. This paper proposes a detection method for conduction current during switching transient of SiC MOSFET based on second-order passive filtering. Under the high-speed variation of drain current during the switching transient, the mutual inductance coil generates an induced potential. The induced voltage can be effectively restored, and the high-frequency oscillation be attenuated by implementing a second-order passive R-C filter. By selecting specific parameters for resistance and capacitance, the analysis of a second-order low-pass filter function validates the feasibility of using filtering time as an equivalent electrical parameter for the conduction current. The effectiveness of a passive filter circuit is validated through double-pulse experiments. The results indicate that the filtering time demonstrates high sensitivity and accuracy to the conduction current during switching transient. Moreover, the filtering time remains unaffected by the rate of drain current, indicating its strong universality and applicability to different specifications of SiC MOSFET modules.