An approach to improve efficiency of EV batteries charger under light load

This paper presented an approach to improve efficiency of EV batteries charger under light load. On the basis of analysis on the original charger built upon capacitor-diode-diode clamp circuit, a modified capacitor-diode-switching clamp circuit was designed to replace the original one in the full-bridge phase-shifted zero-voltage and zero-current-switching PWM DC/DC converter. Operating principle was introduced, and the critical condition to judge whether under light load was derived. Circuit simulation and experiment on the prototype were performed under different loads. Both results show that besides the advantages of the original topology, higher efficiency and less stress on switches are achieved under light load.