Integrated Magnetics Design for an Interleaved Three-Phase Buck Converter

This paper discusses the optimization of a coupled inductor used in a three-phase interleaved buck converter that is part of a two-stage motor drive circuit. To achieve high efficiency and high power density, the converter uses wide-bandgap switch devices to reduce switching losses under high-frequency operation and a coupled inductor that integrate three independent inductors to reduce the number of magnetic components. The relationship between the equivalent inductance of the coupled inductor and the coupling coefficient is discussed for different core shapes under various duty cycles. The three-phase coupled inductor core structure is optimized, and the coupling coefficient is reduced by adding magnetic volume to reduce the inductor current ripple and the core loss. The prototype of the 500-W three-phase interleaved converter operates at 500 kHz with the proposed integrated magnetics technology.