Active junction temperature control of IGBTs for electric vehicle drive system based on hybrid control strategy

Junction temperature swing is the most important factor to induce the IGBTs failure due to the associated internal temperature gradient acting on the mismatch of coefficients of thermal expansion between adjacent layers and internal temperature gradients, and smoothing the junction temperature fluctuation is a valid way to prolong the lifespan of IGBT modules. This paper investigates the dependency of the junction temperature fluctuation smoothing effect on the stator current and switching frequency, and presents a hybrid control strategy to smooth the junction temperature swing. Depending on the heating up or cooling down stages of IGBTs, the proposed strategy adjusts the stator current and switching frequency respectively. For simulation, Urban dynamometer driving schedule (UDDS) for the VEH_SMCAR model in ADVISOR is used to verify the effectiveness, where the evaluated result shows that the proposed method can effectively reduce the number of the large junction temperature fluctuation cycles and the life-span increases by 90 %. Meanwhile, the experimental results also validate the effectiveness of the proposed hybrid control strategy in smoothing junction temperature fluctuation.