Space Vector Modulation Strategies for Three-Phase ANPC Inverter

Abstract

The three-phase active neutral-point-clamped topology has become an attractive solution for high-power applications, as it provides high efficiency and produces voltage and current waveforms with low harmonic distortion. Space vector modulation is widely used to control multilevel inverters because it reduces harmonic distortion, mitigates or eliminates common-mode voltage variations, and ensures balancing of direct-current link capacitors. Several modulation strategies have been proposed for the three-phase active neutral-point-clamped inverter to address these challenges, and this work reviews and compares some of the most relevant approaches. In addition, two space-vector-based modulation strategies are proposed and compared with previously reported methods. The first strategy eliminates common-mode voltage variations by using medium vectors that inherently do not generate them. The second strategy is intended to maintain a constant common-mode voltage over extended intervals by employing small vectors that share the same common-mode voltage level. Finally, experimental and numerical results are presented to assess and validate the main characteristics of the proposal, demonstrating that both proposed modulation strategies effectively reduce the leakage current. The first strategy achieves a 77% reduction compared with conventional modulation, while the second strategy further decreases the leakage current by 83%.