On Ripple Reduction of PWM Coupled Inductors

This letter investigates the ripple reduction mechanisms of pulsed-width-modulated (PWM) coupled inductors based on the principles of multiphase interleaving. By adopting circuit duality and superposition analysis, the ripple reduction ratio of PWM coupled inductors is, for the first time, presented as a function of the ripple reduction ratio of multiphase interleaving and the coupling coefficient of the coupled inductor. The analysis simplifies the assumptions used in previous study, and results in concise and intuitive description of the ripple reduction mechanisms of coupled inductors. The results provide useful guidelines for designing interleaved and coupled PWM converters.