An Electrolytic Capacitor-less Bi-Directional EV On-Board Charger Using Harmonic Modulation Technique

This paper suggests a new electrolytic capacitor-less bi-directional on-board charger for electric vehicle. It has a cascade structure of constant frequency resonant converter for electrical isolation and DCM buck/boost converter for charging/discharging control and input harmonic regulation. Harmonic modulation technique is also proposed to obtain a high power factor and structure change method has been adopted to cope with a wide line voltage condition. Harmonic regulation and charging/discharging control can be accomplished with very simple control algorithm so that high performance controller is not required. Its feasibility has been verified with a 3-kW prototype.