Two Variations of Five-Level Hybrid-Clamped Converters and Their Voltage Balancing Control Using Three Degrees of Freedom

This paper comprehensively utilizes three control freedoms, i.e., switching state selection, zero sequence injection(ZSI) and redundant level modulation(RLM), to maintain capacitor voltage balance in two five-level three-phase converters over the full range of modulation index and power factor. The calculation process of the proposed control method is explained in detail. This method is easy to implement and can be used in other multilevel converters. The first topology is proposed for the first time in this paper. The capacitor voltage controllable region of the second topology has been extended to full operation range without extra circuits. Voltage jumps are found during the deadtime. The performance of the proposed topology and control method is verified by simulation and experiment.