A new two-stage converter with reduction of DC-link capacitor for plug-in electric vehicle battery charger

Abstract

The battery charger manufacturers want high power density with lower size and weight for on-board plug-in electric vehicles. But battery chargers with isolated converters is one of the major barriers for weight and power density. In addition, due to flow of second harmonic ripple in dc-link, a bulky dc-link capacitor is deployed at PFC stage, which has another cause of low power density in two stage battery charging. To deal with above aspects, this study presents a two-stage single-phase non-isolated converter for an onboard plug-in electric vehicles with sinusoidal charging battery method. The first stage is a conventional boost power factor correction (PFC) converter and the second stage is a proposed bidirectional dc/dc converter. In addition that, the second stage bidirectional dc/dc converter also has efficiency improvement compared to conventional two switches buck/ boost converter. The sinusoidal charging method of the battery allows to reduce the dc-link capacitor about 85–90% compared to conventional two-stage charging methods. The simulation results are shown to validate the proposed charger.