High-Density Litz-Wired Integrated Magnetics Combining OBC and LDC Transformers With an Integrated Resonant Inductor for Electric Vehicle Charging Systems

Integrated on-board charger (OBC) and low-voltage DC-DC converter (LDC) system is attractive for electric vehicles (EVs) due to its reduced number of switching devices and magnetic components. This paper proposes a novel high-density integrated magnetic component (IMC) that achieves the integration of the high-frequency transformers of the OBC and the LDC with the resonant inductor of the OBC, which reduces the cost, the weight, and the volume of the charging system. Based on the proposed IMC, the system can simultaneously charge the high-voltage battery (HVB) and the low-voltage battery (LVB). Moreover, an elliptical ring-shaped magnetic shunt is employed to achieve controllable leakage inductance, and Litz wire is adopted to replace the conventional busbar winding of the LDC to reduce eddy-current losses and support high-current output. Detailed analysis and design guideline of the proposed IMC are provided. To validate the feasibility of the proposed IMC, a prototype with an integrated 6.6 kW OBC and 2 kW LDC is built. The experimental results show that the proposed IMC achieves a power density of 660 W/in3 and enables the prototype to achieve a peak efficiency of 98.17