Periodically Swapping Modulation (PSM) Strategy for Three-Level (TL) DC/DC Converters With Balanced Switch Currents
The asymmetrical modulation strategy is widely used in various types of three-level (TL) dc/dc converters, while the current imbalance among the power switches is one of the important issues. In this paper, a novel periodically swapping modulation (PSM) strategy is proposed for balancing the power switches’ currents in various types of TL dc/dc converters. In the proposed PSM strategy, the driving signals of the switch pairs are swapped periodically, which guarantees that the currents through the power switches are kept balanced in every two switching periods. Therefore, the proposed PSM strategy can effectively improve the reliability of the converter by balancing the power losses and thermal stresses among the power switches. The operation principle and performances of the proposed PSM strategy are analyzed in detail. Finally, the simulation and experimental results are presented to verify the proposed modulation strategy.