A Transformerless Push-Pull Partial Power Converter for On-Board EV Fast Charging

This work presents new transformerless push-pull step-down DC-DC converter with partial power processing (PPP) tailored for electric vehicle (EV) on-board charging applications. Unlike conventional push-pull converters, the proposed topology eliminates the use of high frequency transformers (HFTs) and uses only capacitive isolation. The topology mitigates high switch voltage stress problem in conventional push-pull converters, enabling its practical use in high-power EV charging. By processing only a fraction of the total battery voltage and power, i.e., partial power processing (PPP), the converter significantly reduces the voltage and current ratings of the input switches and output rectifiers, allowing the use of smaller, more efficient power devices. This results in reduced converter size, cost, and improved efficiency compared to traditional HFT based full power processing phase-shifted or LLC converters [14]–[19]. The design employs a minimal number of switches at the DC-DC stage and leverages a direct bypass path to deliver most of the charging power directly to the battery, enhancing charging speed and reducing the burden on the converter. Simulation results demonstrate a peak efficiency of upto 98 % without the use of soft-switching techniques. The possible modular nature of the proposed topology also supports scalability for ultra-fast offboard charging systems.