Cell Balancing Method in Flyback Converter without Cell Selection Switch of Multi-Winding Transformer

  • Kim, Jin-Woong ;
  • Ha, Jung-Ik
  • Received : 2015.01.16
  • Accepted : 2015.10.14
  • Published : 2016.03.01


This paper presents a cell balancing method for a single switch flyback converter with a multi-winding transformer. The conventional method using a flyback converter with a multi-winding transformer is simple and easy to control, but the voltage of each secondary winding coil might be non-uniform because of the unequal effective turn-ratio. In particular, it is difficult to control the non-uniform effect using turn-ratios because secondary coil has a limited number of turns. The non-uniform secondary voltages disturb the cell balancing procedure and induce an unbalance in cell voltages. Individual cell control by adding a switch for each cell can reduce the undesirable effect. However, the circuit becomes bulky, resulting in additional loss. The proposed method here uses the conventional flyback converter with an adjustment made to the output filters of the cells, instead of the additional switch. The magnitude of voltage applied to a particular cell can be reduced or increased according to the adjusted filter and the selected switching frequency. An analysis of the conventional converter configuration and the filter design method reveals the possibility of adequate cell balancing control without any additional switch on the secondary side.


Battery management system;Cell balancing;Flyback converter;Multi-winding transformer


  1. L. Shuai, K. A. Corzine, and M. Ferdowsi, “A new battery/ultracapacitor energy storage system design and its motor drive integration for hybrid electric vehicles,” IEEE Trans. Veh. Technol., vol. 56, no. 4, pp. 1516-1523, Jul. 2007.
  2. I. Aharon and A. Kuperman, “Topological overview of power trains of battery powered vehicles with range extenders,” IEEE Trans. Power Electron., vol. 26, no. 3, pp. 868-876, Mar. 2011.
  3. P. A. Cassani and S. S. Williamson, “Design, Testing, and Validation of a Simplified Control Scheme for a Novel Plug-In Hybrid Electric Vehicle Battery Cell Equalizer,” IEEE Trans. Industrial Electronics, vol. 57, no. 12, pp. 3956-3962, Dec. 2010
  4. F. Altaf, L. Johannesson and B. Edgardt, “On thermal and state-of-charge balancing using cascade multi-level converters,” Journal of Power Electronics, Vol. 13, No. 4, pp. 569-583, Jul. 2013.
  5. S. J. Huang, F. S. Pai, and B. G. Huang. “A matching design for ultra-capacitor and Li-ion battery cooperation in electric wheel motors.” IEEE SICE Annual Conf., Aug 2010, pp. 2646-2649.
  6. L. Y. Wang, P. Michael, G. G. Yin, W. Chen, Y. Fu, C. C. Mi, “Battery Cell Identification and SOC Estimation Using String Terminal Voltage Measurements,” IEEE Trans. Vehicular Technology, vol. 61, no. 7, pp. 2925-2935, Sept. 2012
  7. Y. Zhao, H. Yun, S. Liu, H. Jiao, C. Wang, “State-of-charge Estimation for Lithium-ion Batteries Using a Multi-state Closed-loop Observer,” Journal of Power Electronics, Vol. 14, No. 5, pp. 1038-1046, May 2015.
  8. C. Fleischer, W. Wagg, Z. Bai and D. U. Sauer, “Adaptive On-line State-of available-power prediction of lithium-ion batteries,” Journal of Power Electronics, Vol. 13, No. 4, pp. 516-527, Jul. 2013.
  9. W.C. Lee, D. Drury and P. Mellor, “Comparison of Passive Cell Balancing and Active Cell Balancing for Automotive Batteries,” IEEE Vehicle Power Propulsion Conf., Sep. 2011, pp.1-7
  10. W. C. Lee, D. Drury, “Development of a Hardware-in-the-Loop Simulation System for Testing Cell Balancing Circuits,” IEEE Trans. Power Electronics, vol.28, no.12, pp.5949-5959, Dec. 2013
  11. A. Affanni, A. Bellini, G. Franceschini, P. Guglielmi, and C. Tassoni, “Battery choice and management for new-generation electric vehicles,” IEEE Trans. Ind. Electron., vol. 52, no. 5, pp. 1343-1349, Oct. 2005.
  12. A. M. Imtiaz, and F. H. Khan. “Time Shared Flyback Converter” Based Regenerative Cell Balancing Technique for Series Connected Li-Ion Battery Strings.”, IEEE Trans. Power Electron., vol. 28, no. 12, pp. 5960-5975, Dec. 2013.
  13. W. Wang, F. Wu, K. Zhao, L. Sun, J. Duan, D. Sun, “Elimination of the State-of-Charge Errors for Distributed Battery Energy Storage Devices in Islanded Droop-controlled Microgrids,” Journal of Power Electronics, Vol. 15, No. 4, pp. 1105-1118, Apr. 2015.
  14. B. T. Kuhn, G. E. Pitel, and P. T. Krein, “Electrical properties and equalization of lithium-ion cells in automotive applications,” in Proc. IEEE Vehicle Power Propulsion Conf., 2005, pp. 55-59.
  15. C. Pascual and P. T. Krein, “Switched capacitor system for automatic series battery equalization,” in Proc. IEEE Appl. Power Electron. Conf. Exp., 1997, pp. 848-854.
  16. S. G. Song, S. M. Park, S. J. Park, “New Battery Balancing Circuit using Magnetic Flux Sharing,” Journal of Power Electronics, Vol. 14, No. 1, pp. 194-201, Jan. 2015.
  17. J. Sun, C. Zhu, R. Lu, K. Song, G. Wei, “Development of an Optimized Algorithm for Bidirectional Equalization in Lithium-Ion Batteries,” Journal of Power Electronics, Vol. 15, No. 3, pp. 775-785, Mar. 2015.
  18. A. M. Imtiaz, F. H. Khan, “Time Shared Flyback Converter Based Regenerative Cell Balancing Technique for Series Connected Li-Ion Battery Strings,” IEEE Trans. Power Electronics, vol. 28, no. 12, pp. 5960-5975, Dec. 2013
  19. Y. Yuanmao, K. W. E. Cheng, and Y. P. B. Yeung, “Zero - current switching switched - capacitor zero-voltage-gap automatic equalization system for series battery string,” IEEE Trans. Power Electron., vol. 27, no. 7, pp. 3234-3242, Jul. 2012
  20. M. Kultgen and J. Munson, “Battery stack monitor extends life of Li-on batteries in hybrid electric vehicles,” Linear Technol. Mag., vol. 19, pp. 1-8, Mar. 2009.
  21. B. Lindemark, “Individual cell voltage equalizers (ICE) for reliable battery performance,” in Proc. IEEE Int. Telecommun. Energy Conf., 1991, pp. 196-201.
  22. M. Einhorn, W. Roessler, and J. Fleig, “Improved performance of serially connected Li-ion batteries with active cell balancing in electric vehicles,” IEEE Trans. Veh. Technol., vol. 60, no. 6, pp. 2448-2457, Jul. 2011.
  23. J. C. Wu, H.L. Jou, J. H. Tsai, “A Buck-Boost Type Charger with a Switched Capacitor Circuit”, Journal of Power Electronics, Vol. 15, No. 1, pp. 31-38, Jan. 2015.
  24. A. C. Baughman and M. Ferdowsi, “Double-tiered switched-capacitor battery charge equalization technique,” IEEE Trans. Ind. Electron., vol. 55, no. 6, pp. 2277-2285, Jun. 2008
  25. N. H. Kutkut, H. L. N. Wiegman, D. M. Divan, and D. W. Novotny, “Design considerations for charge equalization of an electric vehicle battery system,” IEEE Trans. Ind. Appl., vol. 35, no. 1, pp. 28-35, Feb. 1999.
  26. W. Hu, F. Zhang, Y. Xu, X. Chen, “Output Voltage Ripple Analysis and Design Considerations of Intrinsic Safety Flyback Converter Based on Energy Transmission Modes,” Journal of Power Electronics, Vol. 14, No. 5, pp. 908-917, May 2015.
  27. N. H. Kutkut, D. M. Divan and D. W. Novotny, “Charge equalization of series connected battery strings,” IEEE Trans. Industry Applications, vol. 31, no. 3, pp. 562-568, May 1995.
  28. X. Wei, X. Zhao, and D. Haifeng, “The application of flyback DC/DC converter in Li-ion batteries active balancing,” in Proc. IEEE Vehicle Power Propulsion Conf., Sep. 7-10, 2009, pp. 1654-1656.
  29. J. W. Shin, G. S. Seo, C. Y. Chun, and B. H. Cho, “Selective Flyback Balancing Circuit with Improved Balancing Speed for Series Connected Lithium-ion Batteries,” International Power Electronics Conf, pp. 1180-1184, August 2010.

Cited by

  1. A Flyback-Assisted Single-Sourced Photovoltaic Power Conditioning System Using an Asymmetric Cascaded Multilevel Inverter vol.16, pp.6, 2016,
  2. Design of a CLC Filter for Flyback-Type Micro-inverters of Grid-Connected Photovoltaic Systems vol.63, pp.4, 2017,
  3. A Unified Control Strategy for Inductor-Based Active Battery Equalisation Schemes vol.11, pp.2, 2018,
  4. A Modular Cell Balancer Based on Multi-Winding Transformer and Switched-Capacitor Circuits for a Series-Connected Battery String in Electric Vehicles vol.8, pp.8, 2018,