Magnetizing and Leakage Inductance Integration for Split Transformers With Standard UI Cores

The magnetic elements are the important parts of the dc–dc converters, which is the constriction to improve the power density of the systems. In this letter, a magnetic integration structure is proposed to integrate the magnetizing and leakage inductance for split transformer with standard UI cores, which are mass-produced. Compared with the EI/EE-core structure to achieve magnetic integration, the magnetic field is theoretically evenly distributed in a UI core, and the center leg is removed because of the flux cancelation during the derivation process of the proposed magnetic structure. In this magnetic integration structure, the magnetizing inductance and the leakage inductance can be controlled accurately by designing the numbers of printed circuit board (PCB) windings and the air gap length of the UI core. The derivation process of the proposed magnetic integration and mathematical analysis is studied. The step-by-step design process is investigated, and a design example is given. A 250 kHz, 800 W, 360/380 V
LLC
prototype is built to verify the feasibility of the proposed magnetic integration method.