Compact Integrated Transformer - Grid Inductor Structure for E-Capless Single-Stage EV Charger

This article proposes a planar magnetic integration technique that combines the grid inductors and transformer in the single-stage E-capless electric vehicle charger into one core. The proposed integration technique reduces the number of magnetic components; therefore, the cost, total magnetic core loss, and volume can be significantly reduced. Using the integrated structure, the overall converter power density increases up to 11.1% compared to the nonintegrated one. This article also presents a detailed analysis of the optimal printed circuit board (PCB) winding arrangement considering both ac resistance and winding stray capacitance. Due to the high dc resistance of PCB winding, Litz wire was also considered for the proposed integrated structure. The effectiveness of the proposed structure was validated by implementing it on a 3.7-kW prototype of a single-stage ac-dc converter. Results show that the prototype with the proposed integrated structure achieved higher efficiency with both PCB winding and Litz wire. Peak efficiency of 97.17% and 6.55-kW/L power density were achieved.