A geometrical core constant approach to integrated magnetics design

Integrated magnetics, which incorporates a multiple-output transformer and several coupled inductors on the same core, can reduce the total volume, weight and cost of converters while providing better performance through the coupled inductor current ripple steering phenomena, independent of the converter topology, control, and operation mode. In this paper, an improved integrated magnetics design procedure is developed using a geometrical core constant approach in which the copper power dissipation limit of the integrated magnetics can be specified. The procedure gives the core size, the numbers of turns and the wire gauges of the windings, and the air gap of the component without requiring design iterations. An integrated magnetic structure consisting of a two-output transformer and two coupled inductors designed by this procedure has achieved less than 3% peak-to-peak current ripple on both coupled inductors. Compared to separate magnetics with the same performance, magnetics integration uses about half of the volume by a separate magnetics approach