Inductor design for low loss with complex waveforms

Abstract

An inductor design which uses solid and litz wire in order to attain high efficiency for waveforms with low- and high-frequency components is presented. In previous designs, leakage inductance can increase the portion of the low-frequency component that flows in the litz-wire winding, and thus increase loss. A capacitor in series with the litz-wire winding is proposed to eliminate this effect. An inductor prototype has been built and measurement results verify the benefits of the proposed concept. Both model results and measurements show that loss can be reduced by as much as 20% through adding the capacitor or by 30% compared to a solid-wire winding alone. For design optimization including cost considerations a software tool has been written in MATLAB based on the derived loss model offering a simple step-by-step process for designers.