ANALYSIS OF THE CHARACTERISTICS OF PLANAR POWER MAGNETICS FOR HIGH-FREQUENCY DC/DC CONVERTERS

Although magnetic components combining planar construction windings and flat cores have begun to be applied to planar-type dc/dc converters, there are many unclear points regarding action of the leakage magnetic flux when the core is made extremely thin. In this paper, combining the analysis by finite element method and experiment, the quantization of the influence on excitation inductance and winding loss by the leakage magnetic flux is attempted. Also, the flatter the core is, the more the leakage magnetic flux linking and the winding increase. Also, although there is the advantage that the excitation inductance increases, it was clarified that, on the one hand, it is accompanied by the disadvantage of increase of winding loss by the leakage magnetic flux. Winding losses in various winding constructions are compared, and it is shown that the sandwich construction is the best from the viewpoint of decrease of loss. The suitability of this result was verified by a 1.2-MHz, 126-W prototype voltage resonant dc/dc converter.