A Method for the Suppression of Fluctuations in the Neutral-Point Potential of a Three-Level NPC Inverter with a Capacitor-Voltage Loop

Yun Zhang, Jing Li, Xinmin Li, Yanfei Cao, Mark Sumner, Changliang Xia

Research output: Journal PublicationArticlepeer-review

40 Citations (Scopus)
5 Downloads (Pure)

Abstract

This paper investigates the problem of fluctuation of the neutral-point potential (NPP) in a three-level NPC inverter with a capacitor-voltage loop. The phase pulse width duty cycle disturbance pulse width modulation (PWM) method is proposed to suppress the NPP fluctuation efficiently. Based on the basic carrier-based phase-disposition PWM method, the average pulse neutral-point current model is established. Then, the frequency, amplitude, and equivalent initial phase of the NPP fluctuation are analyzed based on the current model. According to the alternating error of the dc-link capacitor voltages, a capacitor-voltage loop with a quasi-proportional resonant (PR) controller is presented. The control variable, which varies with the modulation index, phase current, load power factor, etc., can be obtained from the quasi-PR controller. Finally, an experimental three-level NPC inverter is described and the validity and feasibility of the proposed method are verified by experimental results.

Original languageEnglish
Article number7422833
Pages (from-to)825-836
Number of pages12
JournalIEEE Transactions on Power Electronics
Volume32
Issue number1
DOIs
Publication statusPublished - Jan 2017

Keywords

  • Capacitor-voltage loop
  • fluctuation suppression
  • neutral-point potential (NPP)
  • three-level NPC inverter

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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