Research on bidirectional active equalization control of lithium battery pack based on inductance
Aiming at the energy inconsistency of each battery during the use of lithium-ion battery packs,an active balancing topology based on inductor energy bidirectional transfer was constructed,and a balancing control strategy of adjacent SOC difference and voltage bivariable was proposed according to the corresponding relationship between OCV and SOC.The energy transfer between the inductor and the lithium battery was realized by the combination of the main loop and the secondary loop mode.Based on the Buck-Boost equalization circuit,the PWM drive signal duty ratio was adjusted to improve the equalization speed and efficiency.The SOC was estimated by the UKF algorithm,and the SOC of each battery was estimated and sorted.The results of charge-discharge and static simulation of lithium battery showed that the SOC difference between battery packs was controlled within 3%,the voltage difference was equalized within 0.01 V,and the equalization speed was increased by 51%compared with the traditional inductance equalization.The results showed that this method could complete the energy balance management of the battery pack well,the efficiency was relatively high,and the service life of the battery was improved.
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