Comparison of Partial Discharge Characterizations under 60 Hz Sinusoidal Waveform and High-frequency PWM Waveform

Partial discharge (PD) is a phenomenon often occurring in insulation system defects, which can significantly affect life and reliability. In this paper, PD behaviors under line-frequency sinusoidal and high frequency Pulse Width Modulation (PWM) waveforms are compared by testing samples with internal void using a 30kV/60Hz and 6 kV high-frequency PD test platforms. The differences of partial discharge inception voltage (PDIV), partial discharge extinction voltage (PDEV), PD pattern diagram and PD charge magnitude are analyzed and compared. The fundamental PD mechanism under AC waveforms is discussed. The different PD behaviors under high-frequency PWM waveforms and line-frequency sinusoidal waveforms are explained based on different slew rates and frequencies.