Asymmetrical dc side operation is a main challenge for the application of bipolar dc distribution system. As a promising solution, dual converters can balance the dc side pole voltages by integrating a center-tapped transformer. This work first proves that interleaving operation of the dual converters can realize harmonics cancellation of the neutral line current by detailed harmonics distribution analysis. Then, a phase shifting strategy is used to offer an additional degree-of-freedom (DoF), where the resultant 2DoF modulation strategy can significantly suppress the common-mode (CM) currents of converters, offering reduced size of CM choke and improved power density of converters.
