Magnetic Integration of Four-Transformer Matrix with High Controllable Leakage Inductance using a Five-Leg Magnetic
Ahmed Nabih, Qiang Li, Fred C. Lee
Abstract
Recently, resonant DC-DC converters have been deployed in many fields such as information and communications technology (ICT) and with electric vehicles (EVs) due to their improved efficiency, density, and reliability. With the introduction of wide-bandgap (WBG) devices coupled with the soft-switching feature, switching frequencies can be extended beyond mega-hertz. However, the design of the magnetic components (trans-former and inductor) becomes more challenging to accommodate for high efficiency, high power density, and lower cost. This paper leverages the printed circuit board (PCB) to integrate a matrix of four transformers plus a resonant inductor in a novel five-leg magnetic core structure. The proposed design allows controllable leakage inductance for the matrix transformer within the footprint of the original matrix transformer, which offers excellent power density for the magnetics. The proposed structure is used to implement a regulated CLL resonant con-verter. The magnetic concept is demonstrated on 3kW 400V/48V CLL converter addresses for the data center applications. The converter achieves a power density of 550W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a peak efficiency of 97.3%.