Observation of PWM-Dependent Chip Deformation of Automotive Power Module

Dominated by the pulse width modulation (PWM), the deformation and strain of the automotive power module challenge the safety and reliability of the electric vehicles (EV). However, the chip-level deformation of the automotive power module affected by the PWM is not available. Based on the electro-thermal-mechanical multi-physics principle, the mathematical models of the deformation of the automotive power module are created in this paper. Besides, a confocal methodology is employed to characterize the in-situ deformation of the bare die in the power module. To emulate the EV mission profile, an active power cycling test rig is set up by using a front-to-front converter. Concerning various continuous PWMs (CPWMs) and discontinuous PWMs (DPWMs), the comparative experiments are observed to assess the PWM-dominated chip deformation of the automotive power module. It is revealed that the CPWMs show higher deformation than DPWMs. Moreover, the DPWM2 has smaller deformation than other DPWMs. These findings might promote the design of the power module and control scheme of the inverter for the industrial applications.