Split Duty Cycle Coupled Multiphase Boost–Buck Converter

Abstract

The classic boost and buck cascaded converter has inductors at the input and output ports of the converters, which makes it ideal interface for bidirectional battery charging applications where accurate current control and low ripple currents are required. This paper proposes a split duty cycle coupled multi-phase variant applied to the cascaded boost-buck converter and utilizing coupled inductor features to achieve very lower current ripples at the output,lower power losses, reduction in magnetic component volume. Moreover, current sharing between each phase is inherently implemented, making it suitable for high conversion ratio bidirectional operation in a systematic energy storage applications where the low voltage port has very high current. The paper covers split duty cycle converter operation principle using coupled inductors between input and the multi-phase output. Magnetic component design and selection guidelines are presented. The proposed control method and coupled inductor structure are validated by simulation and experimental results.