High Efficiency Bridgeless Single-Power-Conversion Battery Charger for Light Electric Vehicles

Charging batteries of light electric vehicles require chargers with high efficiency and a high power factor. To meet this need, this paper presents a bridgeless single-power-conversion battery charger composed of an isolated step-up AC-DC converter with a series resonance circuit. The bridgeless configuration reduces the conduction losses associated with the input diode rectifier, and the series-resonance circuit reduces the reverse recovery losses of the output diodes by providing zero-current switching. In addition, direct and series-resonance current injection enables bidirectional core excitation by the transformer, thereby allowing high power capability. The control algorithm derived from feedback linearization is also developed, which allows the proposed charger to correct the power factor and regulate the output power in a single-stage power conversion. This simple circuit structure leads to high efficiency and a high power factor. The theoretical concepts of the proposed charger are verified experimentally using a 1.7 kW prototype.

Index Terms—Bridge diode, series resonance, power factor correction