高dv/dt方波电压与高温下局部放电导致的功率模块封装绝缘老化与寿命研究

The application of wide bandgap semiconductors poses challenges to the packaging reliability of power modules under high dV/dt square wave voltage and high temperatures. The partial discharge (PD) occurring in the encapsulant is one of the main causes resulting in packaging insulation aging and failure. However, limited research focuses on the effects of temperature and square wave parameters on packaging insulation aging principle and the exact mechanisms remain largely unknown. To address that, this article focuses on the aging process of power module packaging insulation due to PD under high dV/dt square wave and high-temperature coupling stresses. The specially designed down-mixing PD detection system is applied to extract PD signals during aging. The experimental results indicate that the magnitude of PD shows a fluctuating growth trend during aging, and PD activity reaches severest before breakdown. As the temperature rises, the lifetime of the power module packaging insulation decreases, accompanied by an increase in the magnitude and pulse repetition rate of PDs. The longer rise time and lower voltage frequency of the square wave usually lead to longer lifetimes. The effects of temperature, rise time, and voltage frequency on PD behaviors are analyzed based on the discharge mechanism and finite element electric field simulation. Moreover, the total accumulation damage of PD during aging is primarily correlated with temperature, and based on that, the lifetime estimation model of power module packaging insulation considering temperature and PD aging factors is proposed for the first time, which provides the reference for the condition evaluation of the power module.