Instantaneous Balancing of Neutral-Point Voltages for Stacked DC-Link Capacitors of a Multilevel Inverter for Dual-Inverter-Fed Induction Motor Drives

Apurv Kumar Yadav, K. Gopakumar, Krishna Raj, Loganathan Umanand, Kouki Matsuse, Hisao Kubota

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

This paper proposes a novel method for instantaneous balancing of neutral-point (NP) voltages with stacked multilevel inverters (MLIs) for variable-speed drives. The stacked MLI uses series-connected dc sources and NPs (connecting points of dc sources) to obtain the desired levels. The balancing of NP voltages are obtained by using a low-voltage-capacitor-fed cascaded H-bridge (CHB) per phase of a symmetrical six-phase induction machine (IM), which ensures zero current drawn from NPs (at any given instant). Since no current is drawn from NPs, the single dc-link operation with stacked capacitors is also possible. The scheme is suitable for applications, where low-voltage dc sources and batteries are stacked to form a dc link. A variable-speed operation is done using a seven-level inverter scheme for a symmetrical six-phase IM, which is formed by three dc-link stacked capacitors cascaded with two low-voltage-capacitor-fed CHBs per phase. Furthermore, the method is extended for an open-end IM to obtain a seven-level common-mode eliminated space vector structure using a single dc link. The generalization of this method for any stacked n-level inverter without NP voltage deviation is also presented in this paper. The experimental results and analysis are included to validate the proposed method.

Original languageEnglish
Article number8360462
Pages (from-to)2505-2514
Number of pages10
JournalIEEE Transactions on Power Electronics
Volume34
Issue number3
DOIs
Publication statusPublished - Mar 2019

Keywords

  • Cascaded H-bridge (CHB)
  • common-mode elimination
  • induction motor drive
  • multilevel converter
  • stacked inverter

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