It is of paramount importance to measure the operating temperature of power semiconductor devices that form the essential part of electric power drive trains for electric vehicles. This paper introduces an alternative method to determine the junction temperature of Insulated Gate Bipolar Transistor (IGBT) power modules. The proposed scheme relies upon injecting a high frequency/low power signal into the gate-emitter terminals of an IGBT and then analysing the corresponding frequency response characteristics of the gate-emitter circuit. A small-signal model for the gate-emitter impedance of a 100 A IGBT power module has been developed, and its frequency response is examined and analysed by SaberRD. The frequency response of the model is compared with experimental data obtained from a network analyser. Both, simulation and practical results confirm the feasibility to detect the junction temperature of IGBTs.