Advanced Single-Phase Onboard Chargers with Small DC-Link Capacitors

In this paper, a single-phase non-isolated onboard battery charger with small DC-link capacitors is proposed, where the low-voltage battery charger is utilized as an active power filter to reduce the inherent second-order ripple power when the high-voltage (HV) battery is charged from the grid. In this scheme, the large DC-link capacitor banks of the HV battery charger can be eliminated without additional switches, leading to the reduction of cost and volume of the onboard battery charger. Also, this structure of EV chargers has distinctive features of three different modes such as grid-to-vehicle (G2V), vehicle-to-grid (V2G), and HV-to-LV battery (H2L) modes. The simulation and experimental results have verified the effectiveness of the proposed topology.