A dual fuzzy logic controller-based active thermal control strategy of SiC power inverter for electric vehicles

Thermal stress is one of the most important factors leading to power module failure. Under the load condition of high current with low fundamental frequency or largely changed load current, it would cause high junction temperature swing amplitude (JTSA) of chips, which could accelerate the failure of power module. To address this issue, this paper proposes a dual fuzzy logic controller-based active thermal control (ATC) strategy to reduce the JTSA of chips in cases of variable power profiles. Two fuzzy logic controllers are designed to reduce the JTSA of chips by adjusting the switching frequency and pulse width modulation (PWM) strategy, respectively. One fuzzy logic controller is designed to reduce the transient JTSA of chips, which is done by changing the switching frequency according to the fundamental frequency and transient JTSA. The other one is to reduce the mean JTSA of chips, which is implemented by regulating the switching frequency and PWM modes according to the mean junction temperature and its variation. The minimum one is selected as the switching frequency of power inverter. Finally, the effectiveness of the proposed ATC strategy is verified by simulation and experimental results.