Novel Dynamic Resistance Equalizer for Parallel-Connected Battery Configurations

Phuong-Ha La and Sung-Jin Choi
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Phuong-Ha La: School of Electrical Engineering, University of Ulsan, Ulsan 44610, Korea
Sung-Jin Choi: School of Electrical Engineering, University of Ulsan, Ulsan 44610, Korea

Energies, 2020, vol. 13, issue 13, 1-17

Abstract: As the number of parallel battery connections in an energy storage system is increased to extend the energy capacity and second-life batteries are actively adopted, the battery is more prone to cell inconsistency issues. The difference in the internal impedance and the mismatched state-of-charge accelerates the self-balancing effect between the parallel branches to reduce cell utilization and eventually results in harmful effects, both to the lifetime and to the safety of the batteries. However, conventional methods only partially mitigate the parallel inconsistency issue. This paper proposes a dynamic resistance equalizer for parallel-connected battery configurations to improve equalization performance. The optimal design procedure is also presented to minimize the power loss and equalization time. The overall performance is experimentally verified by a sequence of tests for a Li-ion battery in a 2S-4P configuration. The experimental results show that the proposed method dissipates less external power loss than the fixed resistor equalizer and less internal loss than the conventional sequencing method. When both total loss and balancing performance are considered together, as the number of series connections increases, the merits of the proposed method stand out. This is verified by additional hardware-in-the-loop tests, presenting a fascinating feature for most practical battery applications.

Keywords: battery equalization; design optimization; dynamic resistance equalizer (DRE); state-of-charge (SOC); second-life battery energy storage system (SL-BESS) (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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