Improved natural balancing with modified phase-shifted PWM for single-leg five-level flying-capacitor converters

Steven Thielemans, Alex Ruderman, Boris Reznikov, Jan Melkebeek

Research output: Contribution to journalArticlepeer-review

112 Citations (Scopus)

Abstract

Flying-capacitor converters (FCCs), like most multilevel converter topologies, require a balancing mechanism of the capacitor voltages. FCCs feature natural voltage balancing when a special modulation technique is used. The classic methods, such as phase-shifted pulse width modulation (PS-PWM), result in very slow balancing for some duty-ratio ranges. Previous work has shown that for a single-leg five-level FCC, one time constant is infinite for a zero desired output voltage. In this paper, a modified PS-PWM scheme for a single-leg five-level FCC is presented, which results in faster balancing over the total duty-ratio range. The modified PS-PWM scheme is studied, resulting in an averaged voltage-balancing model. This model is verified using simulations and experiments. The modified PS-PWM scheme solves the slow-balancing problems of the normal PS-PWM method for odd-level FCCs, while maintaining the passive control property, and it provides a self-precharge capability.

Original languageEnglish
Article number6030953
Pages (from-to)1658-1667
Number of pages10
JournalIEEE Transactions on Power Electronics
Volume27
Issue number4
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Capacitor voltage balancing
  • multilevel converters
  • power converters
  • pulse width modulation (PWM)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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