MODIFIED BI-DIRECTIONAL CUK CONVERTER FOR CELL BALANCING USING PI AND FUZZY LOGIC CONTROL METHOD

Abstract

In multi-cell battery packs, the Battery Management System (BMS) is the safety system of the battery and is responsible for keeping values such as voltage, current, and temperature within safe limits. One of its most important functions is to eliminate the imbalances caused by the voltage difference between the battery cells connected in series. Active and passive topologies are used to compensate for voltage differences between cells. In passive cell balancing, excess energy is dissipated as heat energy over a resistor, while in active cell balancing systems, excess energy is transferred between cells, thus increasing efficiency. In this study, a modular and converter-based active balancing topology is presented. In the design, there are insulated cuk converter modules that perform bidirectional energy transfer corresponding to each battery cell connected in series. Such a modular design has good flexibility and extensibility for balancing series-connected battery cells. By designing an isolated bi-directional cuk converter circuit and equalization controller, five battery cells connected in series were tested separately in charging, discharging, and idle states. The PI control and fuzzy logic control (FLC) methods have been applied to the proposed topology and verified with the Matlab/Simulink program.

Keywords

• Cell Balancing
• Cuk Converter
• Active Balance
• Battery Equalization
• BMS

References

1. Andrea, D. (2010). Battery management systems for large lithium-ion battery packs, Artech house. https://ieeexplore.ieee.org/document/9100544
2. Andrea, D. (2020). Lithium-Ion Batteries and Applications: A Practical and Comprehensive Guide to Lithium-Ion Batteries and Arrays, from Toys to Towns, Volume 2, Applications, Artech House. https://ieeexplore.ieee.org/document/9219999
3. Ling, R., Dan, Q., Wang, L. & Li, D. (2015). Energy bus-based equalization scheme with bidirectional isolated Cuk equalizer for series connected battery strings, IEEE Applied Power Electronics Conference and Exposition (APEC), 3335-3340, Charlotte, NC, USA. doi: https://doi.org/10.1109/APEC.2015.7104831
4. Zhong, H., Li, J. & Wang, Y. X. (2019). A bus-based battery equalization via modified isolated cuk converter governed by adaptive control, Chinese Automation Congress (CAC), 2824-2828, Hangzhou, China. doi: https://doi.org/10.1109/CAC48633.2019.8996984
5. Ling, R., Dan, Q., Zhang, J. & Chen, G. (2014). A distributed equalization control approach for series connected battery strings, The 26th Chinese Control and Decision Conference (2014 CCDC), 5102- 5106, Changsha, China. doi: https://doi.org/10.1109/CCDC.2014.6853089
6. Bildirici, M. & Karaarslan, A. (2017). Analysis of cuk converter using PI and OCC control method, 13th Int. Conf. Technical Phys. Probl. Eng., 2077-3528, Van, Turkey. http://mikrolit.com/PROCEEDINGS/B14.pdf
7. Karaarslan, A. (2018). Modeling and performance analysis of cuk converter using PI and OCC method, Int. J. Technical Phys. Probl. Eng, (10), (3), 1-5. http://www.iotpe.com/IJTPE/IJTPE2018/IJTPE-Issue36-Vol10-No3-Sep2018/1-IJTPE-Issue36-Vol10-No3-Sep2018-pp1-5.p