Analysis of inductor current sharing in nonisolated and isolated multiphase dc-dc converters

Current sharing among inductors is an important issue in both isolated and nonisolated dc-dc converters. In this paper, average current sharing is in-depth modeled and analyzed for both interleaved multiphase buck converters and isolated current-doubler dc-dc converters. The features and comparison of various current-sharing techniques used in isolated and nonisolated dc-dc converters are presented, and the corresponding design guidelines are provided based on the theoretical analysis. The analysis reveals that the state-of-the-art current-sharing technique for multiphase buck converters cannot be directly applied to isolated current-doubler rectifier (CDR) dc-dc converters to achieve balanced inductor currents. Passive and active current-sharing methods are proposed for isolated current-doubler dc-dc converters to balance two inductor currents. Experimental results are presented to verify the modeling analysis and the proposed current-sharing techniques for CDRs in isolated dc-dc converters.