New modular structure DC-DC converter without electrolytic capacitors for renewable energy applications

Yihua Hu, Wenping Cao, Stephen J. Finney, Weidong Xiao, Fengge Zhang, Seán F. McLoone

Research output: Contribution to journalArticlepeer-review


Electrolytic capacitors are extensively used in power converters but they are bulky, unreliable, and have short lifetimes. This paper proposes a new capacitor-free high step-up dc-dc converter design for renewable energy applications such as photovoltaics (PVs) and fuel cells. The primary side of the converter includes three interleaved inductors, three main switches, and an active clamp circuit. As a result, the input current ripple is greatly reduced, eliminating the necessity for an input capacitor. In addition, zero voltage switching (ZVS) is achieved during switching transitions for all active switches, so that switching losses can be greatly reduced. Furthermore, a three-phase modular structure and six pulse rectifiers are employed to reduce the output voltage ripple. Since magnetic energy stored in the leakage inductance is recovered, the reverse-recovery issue of the diodes is effectively solved. The proposed converter is justified by simulation and experimental tests on a 1-kW prototype.
Original languageEnglish
Pages (from-to)1184-1192
Number of pages9
JournalIEEE Transactions on Sustainable Energy
Issue number4
Early online date14 Sept 2014
Publication statusPublished - Oct 2014

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  • DC-DC converter
  • electrolytic capacitor
  • fuel cells
  • modularization
  • photovoltaics
  • power loss


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