A New Cascaded Multilevel Inverter Topology with Galvanic Isolation

This paper presents a new compact three-phase cascaded multilevel inverter (CMLI) topology with reduced device count and high-frequency magnetic link. The proposed topology overcomes the predominant limitation of separate dc power supplies, which CMLI always require. The high-frequency magnetic link also provides a galvanic isolation between the input and output sides of the inverter, which is essential for various grid-connected applications. The proposed topology utilizes an asymmetric inverter configuration that consists of cascaded H-bridge cells and a conventional three-phase two-level inverter. A toroidal core is employed for the high-frequency magnetic link to ensure compact size and high-power density. Compared with counterpart CMLI topologies available in literature, the proposed inverter has the advantage of utilizing the least number of power electronic components without compromising the overall performance, particularly when a high number of output voltage levels is required. The feasibility of the proposed inverter is confirmed through extensive simulation and experimentally validated studies.