Active Balancing System for Electric Vehicles With Incorporated Low-Voltage Bus

Michael Evzelman, M. Muneeb Ur Rehman, Kelly Hathaway, Regan Zane, Daniel Costinett, Dragan Maksimovic

Research output: Contribution to journalArticlepeer-review

153 Scopus citations


Electric-drive vehicles, including hybrid, plug-in hybrid, and electric vehicles, require a high-voltage (HV) battery pack for propulsion and a low-voltage (LV) dc bus for auxiliary loads. This paper presents an architecture that uses modular dc-dc bypass converters to perform active battery cell balancing and to supply current to auxiliary loads, eliminating the need for a separate HV-to-LV high step-down dc-dc converter. The modular architecture, which achieves continuous balancing of all cells, can be used with an arbitrary number of cells in series, requires no control communication between converters, and naturally shares the auxiliary load current according to the relative state-of-charge (SOC) and capacities of the battery cells. Design and control details are provided for LV low-power dual active bridge (DAB) power converters serving as the bypass converter modules. Furthermore, current sharing is examined and worst-case SOC and current deviations are derived for mismatches in cell capacities, SOCs, and parasitic resistances. Experimental results are presented for a system consisting of 21 series 25 Ah Panasonic lithium-ion NMC battery cells and 21 DAB bypass converters, with combined outputs rated to supply a 650-W auxiliary load.

Original languageEnglish
Article number7368921
Pages (from-to)7887-7895
Number of pages9
JournalIEEE Transactions on Power Electronics
Issue number11
StatePublished - 1 Nov 2016
Externally publishedYes


  • Battery balancing
  • dual active bridge
  • electric vehicle
  • load sharing
  • low voltage bus
  • power converters

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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