A Health-Sensitive Parameter for Noncontact Condition Monitoring of SiC MOSFET in LCL Wireless Charging Circuit

Condition monitoring of SiC MOSFET modules is an effective way to improve the reliability of electric vehicle (EV) wireless charging devices. This paper proposes a new health-sensitive parameter for noncontact monitoring of SiC MOSFET modules in EV wireless charging devices. This parameter can be captured on the charging coil without any electrical connection to the the SiC MOSFET under test. To avoid the influence of battery voltage on the captured parameter, a construction method of two monitoring loops is presented on the inductor-capacitor-inductor (LCL) wireless charging circuit. By comparing the impedance magnitude of the two loops, the impedance magnitude difference at the resonant frequency is selected as the health-sensitive parameter. To ensure its effectiveness in practical applications, the influence of charging coil offset is analyzed, and a calibration method of the parameter is proposed to reduce such influence. Theoretical analysis shows that the proposed parameter is sensitive to the bond wire lift-off and less affected by the coil offset.