IGBT Junction Temperature Measurement via Quasi-threshold Voltage Under Constant Current Source Driver

Thermo-sensitive electrical parameter (TSEP) methods are widely applied in the junction temperature measurement of power semiconductor devices for reliability assessment. This paper proposes a method to measure junction temperatures of insulated-gate bipolar transistors (IGBTs) during the turn-on process. The quasi-threshold voltage is employed as an indicator of a TSEP to extract the junction temperature under constant current source (CCS) driver, utilizing the parasitic inductor between the Kelvin and power emitter terminals of an IGBT module. The relationship between the junction temperature and the quasi-threshold voltage is investigated. A dynamic switching characteristic test platform is established to experimentally verify the theoretical analysis. The experimental results show that the dependency between IGBT junction temperature and quasi-threshold voltage is close to linear but susceptible to bus voltage. Faint impact on junction temperature has been introduced by load current and bond wires lift-off. It can be concluded that quasi-threshold voltage under CCS driver is a potentially practical TSEP for online junction temperature measurement.