A reduced-part single stage direct AC/DC On-board charger for automotive applications

Design of on-board chargers for plug-in electric vehicles (PEVs) is a challenging issue due to size and weight of high-power switching converters, as charging power can be up to 19.2kW in level-2 charging scheme. This paper proposes a reduced-part single stage on-board charger topology, which is integrated to the dc/dc converter used for adjusting voltage levels of battery and dc link during propulsion and regenerative braking. In the proposed topology, one inductor is shared between the dc/dc converter and the charger, eliminating the need for an additional inductor for the charging stage. In charging mode, the proposed interface operates asymmetrical depending on the positive and negative half cycles of the grid. Hence, a charge nonlinear-carrier control method is adopted, and different nonlinear reference voltage waveforms are generated for each half cycles of the grid to ensure unity power factor and stable operation. The operation of the converter is verified through tests carried out for level-1 and level-2 charging and a minimum power factor of 0.99 is achieved at the heavy load condition.