An integrated design of power converters for electric vehicles

This paper proposes a novel integrated power system for electric vehicles (EVs) to improve the power density and efficiency at a less cost. It integrates the on-board charger (OBC) and the low-voltage DC/DC converter (LDC) by common use of semiconductor devices, capacitors and magnetic components. Therefore, the volume and cost of the integrated system is reduced compared with the conventional two independent converters. The proposed system can operate in three modes: OBC standalone mode, LDC standalone mode and OBC-LDC simultaneous mode. The phase-shift control is the main control strategy for this system. For a light load, a PWM plus phase shift (PPS) control is added to provide expending soft switching range. As the most important integrated component, the transformer is designed by considering the soft switching ranges. The theoretical analysis of topology, operating modes, control strategy and transformer design are presented. A prototype integrating a 3.3-kW OBC and a 2-kW LDC is built to demonstrate the validity and advantages of the proposed system.