Novel Modulation with Flexible Power Distribution for Single-Phase Dual-Port DC-AC Converters

Dual-port dc-ac converters utilizing the Neutral-Point-Clamped (NPC) multilevel topology are increasingly considered for the compact integration of multiple sources and loads in various applications. NPC-based dual-port converters (NPCDPC) allow the interconnection of dc and ac systems in a single conversion stage, eliminating the need for magnetics typically required in conventional dc-dc converters. Despite increasing research interest in this area, the majority of studies have focused on three-phase applications, with no documented studies on NPCDPC in single-phase systems to date. This paper introduces a new modulation technique for NPC-DPC connecting two dc sources to a single-phase ac system. The innovative algorithm achieves the twofold objective of ac current control and flexible power distribution between dc sources. The mathematical formulation of the proposed modulation is described and the limits of linear modulation are discussed. To validate the proposed modulation, numerical simulations are conducted and their results are discussed.