Phase-shifted full-bridge converter with integrated flyback operation for high-efficiency light-load EV charging

Photovoltaic (PV)-aided electric vehicle (EV) charging systems are gaining prominence as they reduce dependency on the grid and lower carbon emissions. However, conventional phase-shifted full-bridge (PSFB) converters, although efficient at medium and high loads, suffer from poor light-load performance due to loss of soft switching and increased ripple when pulse-skipping control is employed. This work aims to develop and experimentally validate a load-adaptive integrated PSFB-flyback converter that sustains high efficiency across a wide load range without additional hardware. The proposed approach reconfigures the same full-bridge switching network and isolation transformer to operate in flyback mode during light-load conditions, guided by an online power measurement unit and leveraging inherent device parasitic to support soft-switching operation. A 3 kW PV-aided EV charging prototype is implemented to validate the concept. Compared to a conventional PSFB converter with pulse-skipping control, the proposed scheme improves light-load efficiency from 72.29 % to 86.19 % at 300 W, reducing total converter losses by 13.9 %. The prototype achieves a peak efficiency of 91.75 % at rated power and maintains efficiency above 80 % between 300 W and 900 W. These results confirm that the proposed integrated PSFB-flyback operation provides a simple, cost-effective, and practical solution for PV-aided EV charging systems subject to wide load variation.