Investigations on Online Junction Temperature Measurement for SiC-MOSFETs Using the Gate-Signal Injection Method

This paper presents investigations on the suitability of using the gate-signal injection method for junction temperature measurement of SiC-MOSFETs. The method is based on the temperature sensitivity of the internal gate resistance. A high frequency signal is injected into the gate circuit while the MOSFET is operating. The response of the injected signal is a high frequency current, which depends on the temperature sensitive gate circuit’s impedance. This current causes a voltage drop across the external gate resistor. This voltage depends on the junction temperature and is evaluated. This method was successfully implemented on Si-IGBTs in the past. However, there are challenges to face in implementing this method on SiC-MOSFETs. This paper shows the challenges and proposes solutions to overcome them.