Characterizations of Partial Discharge in Modern Power Electronics

Partial discharge (PD) is a phenomenon often occurring in insulation system defects (cavities), which can significantly affect lifetime and reliability of power electronics components and system. While broad knowledge on PD phenomenology has been achieved under ac sinusoidal voltage, much less work has been discussed to infer PD behavior under emerging high-frequency pulsewidth modulation (PWM) operation conditions. With the introduction of wide bandgap (WBG) power devices to modern power electronics, the insulation voltage stress is high-frequency PWM waveforms with high dv/dt. Moreover, in some complex modular power electronics systems face a superimposed electric stress of two different frequencies, namely, the grid frequency and the switching frequency of converter operation. This article comprehensively reviews the PD test platforms utilized in the characterization of high-frequency transformers (HFTs), power modules, printed circuit board (PCB), and medium-voltage (MV) power converters. In addition, this article compares PD behaviors under 60-Hz sinusoidal waveform and high-frequency PWM waveform. The PD mechanism under PWM pulses and the effect of the slew rate and frequency to PD characterizations are studied. Finally, PD mitigation solutions for modern power electronics components and system are discussed.