Study on the Breakdown Characteristics of Metallized Film under AC/DC Superimposed Voltage

Owing to the advantage of high reliability, metallized film capacitors are widely used in DC-link applications withstanding DC/AC superimposed voltage. An experimental platform for studying the breakdown characteristics of metallized film under AC/DC superimposed voltage was established. The breakdown characteristics of metallized films under different AC/DC voltage ratios were studied. The results show that the distribution of breakdown field strength and breakdown phase angle of metallized film are significantly related to the AC/DC voltage ratio. The breakdown field strength of the metallized film decreases significantly with the increase of $k$ . The breakdown mainly occurs on the rising edge before the peak of AC voltage and keeps approaching the peak as $k$ increases.