Design of Optimized Coupling Factor for Minimum Inductor Current Ripple in DC-DC Converter using Multi-winding Coupled Inductor

The magnetic coupling of filter inductors is widely utilized in various power electronics application fields, including dc-dc converters in EV charger systems, in order to enhance the filtering performance while maintaining the minimal filter size. The optimal distribution of self and mutual inductance of the coupled inductor is regarded as one of the important design tasks with respect to the coupled inductor. This paper proposes a novel method to design the optimal coupling factor for a generalized n-winding coupled inductor, which generates the least size of inductor current ripple in phase-staggered multi-paralleled dc-dc converters. The explicit mathematical form of the optimal coupling factor for a generalized n-winding coupled inductor in n- phase staggered multi-paralleled dc-dc converters is presented. The general equations for the n-winding coupled inductor are verified through the example case of the 3-winding coupled inductor. The experimental results successfully confirmed the newly proposed method of obtaining the optimal coupling factor.