An Asymmetrical Active-Neutral-Point-Clamped Five-Level H-bridge Inverter for Open-Winding Motor Applications With Its Modulation Strategy

Abstract

Asymmetrical active-neutral-point-clamped five-level H-bridge (ANPC5L-HB) inverter has reduced switch count and fewer high-frequency switches compared with other existing five-level H-bridge topologies. However, multiphase ANPC5L-HB inverter for open-winding motor applications is rarely researched. In this paper, a three-phase ANPC5L-HB inverter for open-winding motor applications is proposed. The modulation and neutral point (NP) voltage balance strategies for the inverter are also proposed. By using the proposed modulation strategy, transitions between different switching states are constrained to avoid unexpected intermediate states. Meanwhile, zero voltage switching (ZVS) of low-frequency switches could be achieved. For the NP voltage balance problem, optimal switching states are selected by using the MPC approach, and a better NP control performance is realized compared with the classical method. The effectiveness and high efficiency of the inverter are validated by a 25kW experimental prototype. And a peak efficiency of 98.685% is confirmed under 10kHz switching frequency. The good performances of the proposed strategies have been fully verified.