Analysis and enhancement of high voltage insulation for planar transformer

The planar transformers can be integrated into the isolated DC-DC converters with high manufacturability. To ensure safe operation over the medium voltage isolated DC-DC converters lifetime, the insulation performance of the planar transformer must meet the insulation demand. Designing a planar transformer with an insulation voltage of 25kV is still quite demanding. This paper analyzes the common weaknesses of the high voltage planar transformer. Several solutions are proposed to address these weaknesses. The insulation test and Finite Element Analysis prove the effectiveness of these enhancements. To improve the creepage insulation of the insulation PCB, several effective solutions are proposed. To deal with the high electric field near the insulation PCB and the connector, a PCB-made field grading structure is designed to control the field. The Equivalent Electrode Method is used to optimize the parameter.