Asymmetric PWM for Reliability Enhancement of Multi-Chip IGBT Module in Motor Drive Inverters

In a multi-chip IGBT power module, imbalance of thermal loads among the chips may occur due to differences in thermal impedance and thermal coupling effects arising from their geometry. Thermal load imbalance among chips leads to different lifetime distributions across devices, and the reliability of the power module highly relies on the specific power devices that experience the highest thermal stress. Hence, the reliability of the multi-chip IGBT module could be enhanced by improving the lifetime of chips with the highest stress through the reduction of their thermal loading. In this paper, imbalance of thermal loads among the chips of the multi-chip IGBT module is analyzed through thermal modeling, which includes the thermal coupling effect. Then, the asymmetric Pulse Width Modulation (PWM) method to enhance the reliability of the IGBT power module is proposed and, finally, is verified through comparison with the SVPWM method.