Current ripple cancellation for asymmetric multiphase interleaved dc-dc switching converters

Abstract

Multiphase dc-dc converters are widely used in power electronics, as they enable the processing of high power by splitting the load-current into multiple phases. Conventional multiphase circuits are supplied by a common source, and the goal is to distribute the processed power evenly between the phases. The best possible ripple cancellation can then be performed by shifting the switching operations of each phase by angles of even distance. However, in recent applications, such as maximum power point (MPP) tracking for solar photovoltaic (PV), multiple converters are supplied by sources that are often restricted to operate at different voltages and currents leading to asymmetric converter operation. To achieve improved ripple cancellation under these conditions, phase-shifting by uneven phase-angles is required. In this work, analytic formulas are derived to obtain suitable angles for phase-shifting. Simulations are used to evaluate the performance of the proposed technique, and a practical example of implementation with three dc-dc buck converters is presented.