Analysis and comparative study of different converter modes in modular second life hybrid battery energy storage systems

Nilanjan Mukherjee*, Dani Strickland

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The use of ex-transportation battery system (i.e. second life EV/HEV batteries) in grid applications is an emerging field of study. A hybrid battery scheme offers a more practical approach in second life battery energy storage systems because battery modules could be from different sources/ vehicle manufacturers depending on the second life supply chain and have different characteristics e.g. voltage levels, maximum capacity and also different levels of degradations. Recent research studies have suggested a dc-side modular multilevel converter topology to integrate these hybrid batteries to a grid-tie inverter. Depending on the battery module characteristics, the dc-side modular converter can adopt different modes such as boost, buck or boost-buck to suitably transfer the power from battery to the grid. These modes have different switching techniques, control range, different efficiencies, which give a system designer choice on operational mode. This paper presents an analysis and comparative study of all the modes of the converter along with their switching performances in detail to understand the relative advantages and disadvantages of each mode to help to select the suitable converter mode. Detailed study of all the converter modes and thorough experimental results based on a multi-modular converter prototype based on hybrid batteries has been presented to validate the analysis.
Original languageEnglish
Pages (from-to)547-563
Number of pages17
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number2
Early online date23 Jul 2015
Publication statusPublished - Jun 2016

Bibliographical note

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Funding: EPSRC (EP/1008764/1).


  • boost-multilevel buck converter
  • comparison
  • hybrid battery energy storage system (HBESS)
  • multiple battery types
  • second-life battery energy storage systems (SLBESS)


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