Harmonic Analysis and Neutral-Point Potential Control of Interleaved Parallel Three-Level Inverters for Flywheel Energy Storage System

• Published in: Frontiers in energy research 2022-01, Vol.9
• Main Authors: Li, Zhongrui, Nie, Ziling, Xu, Jie, Li, Huayu, Ai, Sheng
• Format: Article
• Language: English
• Subjects: flywheel energy storage system; harmonic analysis; interleaved; neutral-point potential control; parallel operation; three-level inverter
• ISSN: 2296-598X; 2296-598X
• DOI: 10.3389/fenrg.2021.811845

Flywheel energy storage system is a popular energy storage technology, in which inverters are the center of electrical energy conversion, directly affecting the power capacity. Parallel operation of three-level inverters is an effective approach to achieve larger motor drive power and the interleaved operation can improve the harmonic characteristics. However, harmonic analysis models of the interleaved parallel three-level inverters are rare in the literature and how the neutral-point potential imbalance affects the harmonics characteristics has not been discussed. This article establishes the harmonic calculation for balanced and unbalanced neutral-point potential through the five-level voltage capability of the interleaved parallel three-level inverters. Moreover, a neutral-point potential control method based on zero-sequence voltage injection is proposed. The implement process of the method is proposed, and how the operating frequency affect the ability of the neutral-point potential balance is studied. Finally, the simulation and experiment results verify the feasibility and practicability of the established harmonic analysis models and the neutral-point potential control method.