Integrated Grid Inductor-Transformer Structure with Reduced Core Loss and Volume for E-Capless Single-Stage EV Charger

This paper presents the design and optimization of an integrated magnetic structure that combines the grid inductors and transformer in the single-stage EV -charger. The proposed integration technique reduces the number of magnetic bodies, hence reducing the cost and total magnetic core loss while increasing the power density. By utilizing the fixed 50% duty cycle operation of the converter, a further reduction in core loss can be achieved resulting in improved light-load efficiency. This paper also presents an analysis of the optimal PCB winding arrangements for the proposed structure to achieve low winding AC loss and stray capacitance. To validate the proposed integrated magnetic structure, a 3.7 kW single-stage AC-DC converter prototype with four different cases of magnetic structures is built. Experimental comparison of these four cases shows that the proposed integrated magnetic structure has higher efficiency and power density compared to the non-integrated ones. U sing the proposed integrated magnetic structure, the core loss that dominates at light-load is improved resulting in an increase of efficiency by 0.9%. At the same time, the proposed integration technique reduces the number of magnetic cores as well as total core volume, reducing the cost and improving the converter power density by up to 11.1 %.