Ripple minimization in asymmetric multiphase interleaved DC-DC switching converters

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. Ripple minimization can then be performed by shifting the switching operations of each phase by angles of an 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 based on given operating conditions. Moreover, a resulting control technique is presented. Simulations are used to evaluate the performance of the proposed technique in the aforementioned application of MPP tracking. Measurements taken from an experimental prototype, which consists of three dc-dc buck converters, further validate the results.