Switching Pattern Analysis of Coupled Multi-phase Boost-Buck Converters

Split duty cycle coupled multi-phase variant of the cascaded boost-buck converter with multiphase low voltage buck stage, suitable for bidirectional operation provides benefits of low current ripple, small magnetic component size and high efficiency. This paper proposes an enhancement to split duty cycle switching pattern that would result in a further reduction in ripple current values in each buck phase, resulting in a much lower losses during operation and hence more efficient operation can be achieved, suitable for bidirectional operation where the low voltage port has high current, requiring a multi-phase buck stage. The paper covers split duty cycle vs. alternating split duty cycle converter operation principle using coupled inductors where the selected magnetic component used in both switching patterns is the same. Proposed analysis is validated by simulation and experimental results.