A dual-objective stage-by-stage equilibrium control strategy

Abstract

The invention discloses a dual-objective and phased equalization circuit control strategy of a battery pack. It is known that the working condition consistency of a battery is jointly decided by a battery end voltage and an open-circuit voltage according to a battery equivalent circuit model, while the open-circuit voltage and SOC are in one-to-one corresponding linear relation within a certain range; dual objectives means that the single battery end voltage and the SOC of a single battery are simultaneously used as equalization indexes to achieve voltage equalization and SOC equalization; and phase division means that the voltage is equalized and then the SOC is equalized within an equalization period to achieve battery end voltage equalization and SOC equalization, and the equalization of the battery end voltage and the open-circuit voltage is finally achieved. By the control strategy, the inconsistency of single batteries in the battery pack can be fundamentally eliminated. The control strategy is applicable to a battery equalization management system of an energy storage device in a hybrid electric vehicle, a pure electric vehicle or an energy storage base station.

Description

technical field [0001] The invention relates to a battery group equalization technology, which is suitable for a battery equalization management system of a hybrid electric vehicle, a pure electric vehicle or an energy storage device in an energy storage power station. Background technique [0002] In recent years, with the deteriorating air quality and the scarcity of oil resources, new energy vehicles, especially pure electric vehicles, have become the development hotspots of major automobile companies in the world today. The power battery pack is a key component of an electric vehicle, and the power battery, as a key component of an electric vehicle, has a major impact on the power, economy and safety of the vehicle. [0003] Due to the limited capacity of single cells and the low voltage of single cells, power battery packs are generally composed of multiple single cells connected in series and parallel to meet the requirements of use. In this way, in actual use, due to...

AI Technical Summary

Problems solved by technology

For the research on the control strategy of the balance circuit, Kobzev, Tae-hoon Kim, etc. all use the battery terminal voltage as the balance index to balance the battery pack. However, the performance of the battery cannot be measured only by the voltage, and the capacity of the battery pack is low When charging or after charging, the terminal voltage of the battery may be higher than that of other batteries. If this equalization method is adopted, the result of equalization is that the battery with low capacity will supplement the energy of the battery with high capacity, which will increase the power of each battery in the battery pack. capacity gap

Danielson, Huang W and others believe that the advantage of using SOC as the balance variable is that when the current changes suddenly under different working conditions, it will not cause the battery state of charge to fluctuate, making the change of the balance target relatively stable, which is conducive to reducing the impact of balance shocks on the battery, but This equalization method can only solve the problem of performance degradation of the battery with a larger capacity in the battery pack due to long-term insufficient charging, and cannot reduce or eliminate the gap in the actual capacity of each battery.

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