Online Junction Temperature Measurement via Internal Gate Resistance during Turn-On

A new method for junction temperature measurement of power semiconductor switches is presented. The measurement exploits the temperature dependent resistance of the temperature sensitive electrical parameter (TSEP): the internal gate resistance. This dependence can be observed during the normal switching transitions of an IGBT or MOSFET, and as a result the presented method uses the integral of the gate voltage during the turn-on delay. A measurement circuit can be integrated into a gate driver with no modification to converter or gate driver operation and holds significant advantages over other TSEP based measurement methods, primarily being: an absence of any dependence on operating conditions such as load current, and the potential to achieve higher sensitivity (20mV/C or more) than alternative TSEPs.