Abstract
High-frequency voltages and the thermal effects cause a premature insulation breakdown, a key issue on High-frequency power transformers (HFPT). An experimental setup containing a ball-plate and breakdown measurement unit was established under high-frequency voltages. This paper builds a multi-physical field coupling model using the finite element method. The model studied the coupling effect of voltage, frequency, and temperature. We applied sinusoidal voltage with an amplitude of 2 kV, 3 kV, and a frequency of 20kHz, and 30 kHz to the polyimide (PI) film. At 2kV, the maximum amplitude is 0.03 and 0.037 with the increase of frequency. At 3kV, the maximum amplitude is 0.048 and 0.052 at the respective frequencies. As the frequency increased, there were fewer discharges but maximum discharge amplitude. The phase width of the partial discharge in the positive and negative half cycle affects by the applied voltage magnitude and frequency. The effects of breakdown strength were maximum influenced by voltage and frequency. The acceleration of electric breakdown due to high-frequency sinusoidal voltages is revealed to be enhanced by dielectric heating. Additionally, high-frequency voltages contributed to the increased electric field and dielectric loss, reducing breakdown strength.
Published Version
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