Fault tolerant circuit topology and control method for input-series and output-parallel modular DC-DC converters

Vijay Choudhary, Enrique Ledezma, Raja Ayyanar, Robert M. Button

Research output: Contribution to journalArticlepeer-review

136 Scopus citations


This paper presents a modular, fault tolerant dc-dc converter topology that utilizes common duty ratio control to ensure equal sharing of input voltage and output current in input-series output-parallel configuration. The input-series connection allows the use of low voltage MOSFET's optimized for very low RDS,ON resulting in lower conduction losses. The common-duty-ratio scheme does not require a dedicated control loop for input voltage or output current sharing. The fault tolerant protection and control scheme accommodates failure of one or more modules, and ensures input voltage and load current sharing among the remaining healthy modules. The design of a new sensing scheme for detection of fault is presented. The analysis of the topology and the underlying principles are presented. The dependence of peak current from the source and in the protection switch in case of failure of a single converter has been analyzed and the various design tradeoff issues are discussed. The theoretical predictions are validated with simulation and experimental results. The proposed method is simple and gives good dynamic response to changes in input, load, and during fault. This topology is especially suited for space applications where a high level of fault tolerance can be achieved through designed redundancy.

Original languageEnglish (US)
Pages (from-to)402-411
Number of pages10
JournalIEEE Transactions on Power Electronics
Issue number1
StatePublished - Jan 2008


  • Autonomous control
  • Common duty ratio
  • Fault tolerance
  • Input-series and output-parallel (ISOP)
  • Input-series connection
  • Input-voltage sharing
  • Load-current sharing
  • Modular dc-dc converters

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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