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

Abstract

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 injections enable 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.