Enhanced bipolar stacked switched capacitor energy buffers

Khurram K. Afridi, Minjie Chen, David J. Perreault

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The stacked switched capacitor (SSC) energy buffer is a recently proposed architecture for buffering energy between single-phase alternating and direct current. When used with film capacitors, it can increase the life of grid-interfaced power converters by eliminating limited-life electrolytic capacitors while maintaining comparable energy density. This paper introduces an enhanced version of the bipolar SSC energy buffer that achieves higher effective energy density and round-trip efficiency while maintaining the same bus voltage ripple ratio as the original design. Furthermore, the enhanced buffer uses fewer capacitors and switches than the original design. The enhancement in performance is achieved by modifying the control and switching patterns of the buffer switches. A prototype enhanced SSC energy buffer, designed for a 320-V bus and a 135-W load, has been built and tested. The design methodology and experimental results for the enhanced SSC energy buffer are presented and compared with the original design. This paper also presents a comparison of unipolar and bipolar SSC energy buffers. It is shown that, although bipolar designs are superior in terms of effective energy density at low ripple ratios, unipolar designs can outperform bipolar designs at high ripple ratios.

Original languageEnglish (US)
Article number6567991
Pages (from-to)1141-1149
Number of pages9
JournalIEEE Transactions on Industry Applications
Issue number2
StatePublished - 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


  • AC-DC power conversion
  • dc-ac power conversion
  • electrolytic capacitors
  • energy storage
  • film capacitors
  • switched capacitor circuits
  • twice-line-frequency energy buffer


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