High efficiency isolated on-board EV battery charger using LLC resonant converter

In this study, high efficiency design of an on-board Electrical Vehicle (EV) battery charger is presented. The presented charger has two stages, where the first stage is conventional front-end boost converter, and the second stage is LLC resonant converter. The basic principles of both stages are discussed, and the detailed design procedures are presented in terms of wide range output voltage regulation, wide range load condition, high efficiency, and high power density. The presented design approach is tested with a prototype implemented with 2.5 kW output power at 250 V-450 V output voltage range. The peak efficiency of system is obtained as 95.53% at full load condition.