A New Multilevel AC/DC Topology Based H-Bridge Alternate Arm Converter

Abstract

The current popular modular multilevel converter topology (MMC) needs a large number of cascaded sub modules and switches, a high voltage level of DC bus and a large loss. Based on these problems, a new multilevel converter topology with H-bridge alternate arm is proposed. This topology combines two structures of H-bridge sub module cascade and H-bridge switch series arm. In high-voltage and high-power applications, on the premise of outputting the same AC voltage level, this topology reduces the DC bus voltage level, system loss and cost, and the number of components, simplifies the control method, and improves the system reliability compared with the MMC structure. In this paper, the working mechanism of the topology is described in detail. On this basis, the control strategy of sub module capacitor voltage balancing is proposed. Finally, the PSIM simulation of the topology is carried out, and a single-phase prototype is made in the laboratory. The simulation and experimental waveforms are obtained, which verify the correctness and feasibility of the topology structure.

Keywords

• Multi-level
• high voltage and large capacity
• H-bridge alternate arm
• voltage balancing of sub module capacitor