A Novel Integrated OBC and LDC System with Improved Cross-Regulation Performance for Electric Vehicles

This article presents a novel integrated on-board charger (OBC) and low-voltage dc-dc converter (LDC) system to improve the cross-regulation performance of electric vehicles. The proposed system improves the cross-regulation performance of OBC and LDC by using the magnetically decoupled OBC and LDC windings of a single transformer. Based on the above winding structure of the transformer, the proposed system operates as a dual active bridge converter for OBC and an inductor-inductor-capacitor (LLC) resonant converter for LDC without additional devices, resulting in an improvement in cross-regulation performance. Furthermore, it inherently mitigates the unintended high-voltage problem on the input dc-link capacitor caused by the multiwinding transformer in the LDC standalone mode without any additional control method. To validate the proposed system, an experimental prototype with an integrated 3.3-kW OBC and 1.0-kW LDC is configured and tested.