A contribution to the design optimization of resonant inductors for high power resonant DC-DC converters

The design and optimization of resonant inductors with ferrite cores and foil windings are presented. Finite-difference simulations show that the 1-D approximation of the magnetic field is valid for small airgaps. A method to maintain 1-D H-fields when large airgaps are required is presented. Analytical expressions for the high-frequency AC-resistance of the winding is derived. An optimization routine to minimize core and conduction losses of the inductor is shown. Experimental results on prototypes for a 2 kW converter are presented and discussed. The losses in the new inductor are three to four times smaller compared to the inductor with one large airgap