Modeling Electrical Aging of Polyimide Kapton HN Under High-Voltage High-Frequency Pulse Waveforms

Large voltage transients due to power electronic inverters are one of the major factors influencing the insulation lifetime. This article studies the effect of square voltage transients and switching frequency on insulation breakdown time based on the series of voltage endurance tests. A medium-voltage power-electronics inverter testbed is built to stress polyimide films Kapton HN with square waveforms at different frequencies. The voltage endurance test data are used to develop behavioral aging models and identify the effect of voltage transients and switching frequencies on insulation breakdown time. Results show a new correlation between switching frequency, insulation thickness, and voltage stress that have not been covered in the literature before.