Active charge balancing is a commonly used method to increase the usable energy of a battery stack with serially connected battery cells with different cell capacities. In this article an active charge balancing method with a multiple winding transformer DC/DC converter is described. The advantage of active charge balancing is shown using a prototype with twelve serially connected Lithium ion battery cells. Moreover, the influence of the cell capacity variance and the influence of the balancing current on the discharging energy is investigated. If several Li-ion battery cells are serially connected to a battery stack, the weakest cell limits the performance in terms of usable energy of the whole battery. When the charging/discharging voltage limit of one cell is reached, charging/discharging has to be stopped regardless how much energy is left in the other cells. If the cell capacities in a battery stack are different, active balancing helps to improve the performance of a battery stack remarkably. For a specific battery stack the usable energy was increased by 13% with active cell balancing. The influence of the balancing current and the capacity variance on the discharging energy in a battery stack was investigated. The discharging energy in a battery stack can already be increased significantly with a small balancing current especially for large capacity variations.
Charge balancing of serially connected lithium-ion battery cells in electric vehicles
Ladungsausgleich von in Serie geschalteten Lithium-Ionen-Batteriezellen in elektrisch betriebenen Fahrzeugen
e & i. Elektrotechnik und Informationstechnik ; 129 , 3 ; 167-173
2012
7 Seiten, 17 Bilder, 37 Quellen
Aufsatz (Zeitschrift)
Englisch
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