A Junction Temperature Online Monitoring Method for IGBTs Based on Turn-off Delay Time

Online monitoring of junction temperature (T_j) for insulated gate bipolar transistors (IGBTs) is an important basis for life prediction and health management of IGBT devices. Because the traditional turn-off delay time monitoring method needs to measure multiple signals or only applies to the IGBT structure with Kelvin emitter. To this end, this article proposes an online monitoring solution with thermal sensitive electrical parameters (TSEP) based on the redefining turn-off delay time (t_re-doff), which only depends on the gate voltage signal without real-time acquisition of collector-emitter voltage or collector current. The experimental results have verified the correctness of the relationship between the redefining turn-off delay time and junction temperature. The proposed online monitoring method of IGBT junction temperature is feasible and has the advantages of simplicity, low cost, and high linearity with the maximum measurement error and error percentage of 3.3 °C and 4.5%, respectively.