A DC/DC Fast Charger for Electric Vehicles with Minimum Input/Output Ripple Based on Multiphase Interleaved Converters

An off-board dc fast battery charger for electric vehicles (EVs) with an original control strategy aimed to provide minimum input voltage ripple and zero output current ripple in the typical EV batteries voltage range is presented in this paper. Currently, due to an infant development stage of high-power, high-energy batteries for EV application, there is no clear consensus on allowable output current ripple for fast chargers. However, there are different charging protocols, which are optimized for short charging time and efficiency, while maintaining a long-life cycle of a battery. Common feature of these protocols is an underlying assumption of minimum (or null) instantaneous charging current ripple. The fast charger configuration proposed in this paper is based on a modular three-phase interleaved converter, used as an interface between the dc-link (dc supply) and the battery. The use of low-cost, standard and industry-recognized three-phase power modules for high-power fast EV charging stations enables the reduction of capital and maintenance costs of the charging facilities, enhancing further expansion of the eco-friendly transport. Numerical simulations are carried out in Matlab/Simulink to confirm the feasibility and the effectiveness of the whole EV fast charging configuration, with emphasis to input voltage ripple and output current ripple of the interleaved three-phase dc/dc converter.