High-Temperature Partial Discharge Characteristics of Power Module Packaging Insulation Under Square Pulse With High Dv/Dt Based on Down-Mixing Method

Abstract

Partial discharge (PD) in the high voltage packaging insulation under square pulse with a high slew rate (SR or dV/dt) is one of the main causes of the power module failure, especially for wide bandgap (WBG) devices. But PD under fast square pulse at high temperatures is rarely studied and one of the critical reasons is the lack of an effective PD detection method under fast square pulses. In addition, the existing PD standard defines the PD criterion under sinusoidal alternating current (AC) situations, which is not the actual working condition of the power module. To address that, this paper proposes a down-mixing PD detection method and explores the influence of temperature on the PD characteristics of the power module packaging insulation. The results show that the partial discharge inception voltage (PDIV) decreases as the temperature increases. The PDIV under square pulse is always higher than that under AC voltage. The less the SR and the greater the pulse width (PW) of the square pulse, the lower the PDIV. Physical-based models for PDIV estimation concerning SR, PW, and temperature are proposed for industrial reference. Moreover, statistical analysis of PD magnitude, number, and occurrence phase under square pulse indicates that PD number decreases but PD magnitude increases with the increase in temperature. Higher temperature leads to PDs with large magnitudes, which may accelerate the degradation of packaging insulation.