Development and Demonstration of Bi-directional Battery Charger for E-Mobility Charging Station

In this paper, a modular system was designed to connect E- mobility such as electric motorcycles to the battery charging station. The proposed modular system consists of an AC-DC converter and DC-DC converters. For AC-DC converters, although the grid-connected inverter is used prevalently, it has a large filter under a low switching frequency. A bridgeless totem-pole-based power factor correction (BT-PFC) is applied for high efficiency and high-power density. The 3-kW BT-PFC is implemented to handle the two battery packs. In the case of CC-CV chargers can be used in consideration of the battery charging characteristics. Since the nominal voltage of the Li-ion battery is about 36V, an isolated DC-DC converter is applied for voltage step-down from 400V to 50V. Also, the bi-directional buck-boost converter is connected in series to control the battery voltage. Experimental results with a 3.3-kW laboratory prototype battery charger validate the effectiveness of the proposed development.