Elimination of collector current impact in TSEP-based junction temperature extraction method for high-power IGBT modules

Insulated gate bipolar transistor (IGBT) modules are widely employed in high-power conversion systems. Their junction temperature ranks as one of the most important factors in the reliability of power semiconductor devices. Thermo-sensitive electrical parameter (TSEP) is regarded as the promising solution to extract the junction temperature due to its non-invasion measurement, fast response and high accuracy. However, accurate collector current measurement is required if only the individual TSEP is adopted, which increases the complexity and cost. In this paper, the combined TSEP method is proposed to eliminate the influence of collector current (IC), where the turn-off delay time (tdoff) and maximum decrease rate of IC(max dIC/dt) are adopted and combined. The two TSEPs both have linear relationships with junction temperature and IC. When they are combined mathematically, the influence of IC is eliminated. Experiments have been implemented to validate the effectiveness of the proposed approach. The comparison between combined TSEP and two individual TSEP methods are illustrated and analyzed.