Lithium battery pack stepless active and passive equalization circuit and method

Abstract

The invention relates to a lithium battery pack stepless active and passive equalization circuit and method. The circuit comprises an equalization direction selection circuit, a switch array and an LCresonance energy storage and energy transfer branch with three differentiated capacities, and the passive equalization circuit adopts a resistance shunt structure and comprises a measurement and control circuit composed of voltage, current and temperature. Temperature interference factors are added into the non-level active and passive equalization method, a dynamic double-threshold criterion with voltage, SOC and temperature as input quantities is obtained, and the active equalization circuit and the passive equalization circuit are respectively accessed by taking state of charge (SOC) as ademarcation standard, so that the purpose of reducing invalid cyclic charging and discharging times is achieved, the equalization efficiency is improved, and the reduction speed of the cycle service life of the lithium-ion battery pack is delayed. According to the invention, useless cyclic charging and discharging times can be reduced, the equalization time is shortened, the equalization time in acharging state is shortened by about 15% compared with a single threshold voltage equalization method, and the equalization time in a discharging state is shortened by about 19%.

Description

technical field [0001] The invention belongs to the technical field of battery equalization, and in particular relates to a non-hierarchical active and passive equalization circuit and method for a lithium battery pack. Background technique [0002] In the era of new energy development and utilization and increasing demand for energy storage technology, lithium-ion batteries, as environmentally friendly energy storage components with great development value, are widely used in electric vehicles, portable electronic products, military, aviation and other fields . Lithium-ion battery is a kind of rechargeable battery, which has the advantages of high energy density, low self-discharge rate, high working voltage, and long life. It is more effective in industrial environments that require energy storage devices. In order to meet the needs of different voltages and powers, lithium-ion batteries are often connected in series and parallel, which exposes the problem of inconsistenc...

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Problems solved by technology

[0006] (3) The battery capacity or remaining capacity is used as the balance criterion, and it is very easy to have extreme changes in the voltage or state of charge of the single battery when each single battery is charged or discharged with the same amount of electricity;

[0007] (4) Establish a balanced control strategy based on the open-circuit voltage. The charge-discharge characteristic curves of various types of batteries are inconsistent and are easily affected by the working environment. Moreover, during the rest period of measuring the open-circuit voltage of the battery, it is very easy to cause instability due to error fluctuations. The accuracy inaccuracy problem

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