Fig. 1. The system structure of 11kW on-board charger (a) and battery charging profile (b).
Nowadays, electric vehicles (EV) are becoming more and more popular. Consumers are greatly interested in the on- board battery chargers (OBC) with higher power capability for faster charging time. The typical system structure of OBC is a frond-end ac-dc stage, followed by a step-down dc/dc converter, as shown in
Fig. 1. In this paper, the design considerations of the two-stage on-board charger are introduced, including the optimization of PCB-based magnetic design and the control strategy between stages.
A 11 kW on-board charger prototype with 57W/in3
power density is demonstrated and the efficiency of the system is above 96% over the whole battery voltage range, as shown in Fig. 2.
Fig. 2. The overall efficiency of the system: (a) ac/dc stage and (b) dc/dc stage.