Optimal Design of Resonance Parameters for Minimizing Common-Mode Leakage Current and Narrowing Frequency Operating Range in SRC Converter for Electric Vehicle On-Board Charger

This paper explores the high-density optimization of the on-board charger (OBC) system, the charging system for electric vehicles. The OBC comprises a power factor correction (PFC) stage converting AC input to DC output and a DC–DC stage generating a wide range of final output voltages based on the PFC stage&quots DC output. While isolated LLC resonant converters with excellent ZVS are commonly used in the DC–DC stage, the large transformer in LLC resonant converters designed for broad output ranges limits high-density design. This paper therefore proposes a non-isolated series resonant converter (SRC). However, SRCs face safety concerns due to the overlap of common mode (CM) leakage current from Y-capacitors for EMI reduction, and operational challenges from ground fault circuit interrupter tripping. To address this, the paper analyzes the causes of CM leakage current, presenting a design method for resonance parameters to minimize CM leakage and reduce the operating frequency of the SRC.