Modular symmetric and asymmetric reduced count switch multilevel current source inverter

Abstract

Current source inverters (CSIs) have prominent features compared to voltage source inverters. The CSIs are less affected by grid voltage fluctuations, their control is simple and they have inherent short-circuit protection. This study proposes a novel multilevel CSI based on modular cells. The proposed topology is performed based on the parallel connection of two-switch modules. According to the value of current sources in each module, the proposed configuration can be operated in two modes of operation: symmetric and asymmetric. A comparison study is carried out between the proposed topology, the cascaded H-bridge and a recently developed topology in terms of the number of switches, the number of sources, total switch device power, and power losses. The comparison study shows a great improvement in performance of the proposed symmetric and asymmetric topologies compared to conventional structures. In addition, the proposed circuit shows an interesting feature which is the common emitter connection of the main switches. This arrangement leads to simple gate drive circuits. Finally, seven-level symmetric topology and fifteen-level asymmetric topology are simulated and the laboratory prototypes of them are implemented. The presented simulation and experimental results validate the feasibility of proposed topologies.