Optimal design and control of OBC-LDC integrated power unit for electric vehicles

This paper proposes an integrated circuit sharing internal parts of a low voltage DC-DC converter (LDC) and an on-board charger (OBC) for electric vehicles (EVs). The proposed circuit structure can be operated as an OBC standalone mode, a LDC standalone mode, and a simultaneous operating mode. The operating modes of the proposed system are analyzed and the advantages and disadvantages are also discussed. To improve the derived disadvantage, the expanded circuit structure is suggested and applied. Through this, the practicality of the integrated OBC with LDC is enhanced. The additionally suggested circuit is a built-in zero voltage switching (ZVS) buck unit. Prototype rated with 3.3 kW OBC and 1 kW LDC is built and the experimental results are carried out in order to verify the performance and the validity of the proposed power unit.