Partial Discharge Test of High-frequency Transformers with Plastic Mold for SST

This paper reports on a fundamental evaluation of high-frequency molded transformers for solid-state transformers (SSTs). The high-frequency transformers of DC/DC converters for SST require high-voltage isolation between the primary and secondary windings. In this paper, a molded transformer with high insulation reliability is employed and evaluated by a partial discharge test, which estimates the lifetime of the insulation material. Experimental results show that the mold transformer has a discharge starting voltage of 9.67 kV for the molded transformer and 2.66 kV for the unmolded transformer, which is advantageous for the insulation of the molded transformer.