Bypass type battery equalization device and control method

Abstract

The invention designs a bypass type battery equalization device and a control method. The device comprises a battery pack formed by connecting a plurality of single batteries in series, a constant current module, a charging control module, a bypass module, a sampling module, a control module and a discharging control unit. Compared with the prior art, the balanced energy comes from the external charging power supply, the discharging process of the single battery with high energy is avoided, the discharging frequency of the single battery is reduced, and the service life of the battery is prolonged; in the process of charging the single batteries with relatively low energy, the constant current module and the bypass module are coordinated and matched, so that the fully charged single batteries are protected, the overcharge phenomenon of the batteries is avoided, and meanwhile, all the single batteries can be fully charged, so that the effective capacity of the battery pack is fully utilized; through bypass module current control, energy loss is reduced; and an equalization circuit does not need to specially carry out digital control on each battery monomer, so that the workload of a CPU in the BMS is reduced.

Description

technical field [0001] The invention relates to a battery bypass type active equalization device, which belongs to the management system of related batteries such as lithium ion batteries, in particular to an equalization circuit for equalizing a plurality of single batteries in series. Background technique [0002] With the development of lithium battery and energy storage technology, the requirements for battery management system are getting higher and higher. If multiple single cells are connected in series, due to the inconsistent performance of the single cells, there will be imbalance problems during the charging and discharging process, which will cause the aging of the battery and affect the life and safety of the battery. [0003] At present, methods for balancing batteries mainly include passive balancing methods and active balancing methods. Among them, the passive equalization method is mainly the resistive energy consumption type. A resistor shunt is connected ...

AI Technical Summary

Problems solved by technology

Regardless of whether inductive energy storage or capacitive energy storage is used, multiple high-speed switching power switching devices are required, the cost is high, the control is complicated, and it is impossible to perform equalization control on any single battery at the same time, so the equalization efficiency is low

[0005] Chinese patents CN104577227A, CN104201743, CN107785957A, and CN107834655A disclose several centralized active equalization circuits using transformer isolation or DC / DC converters. Since only one transformer is used to balance all single cells, the transformer has many taps and is difficult to manufacture and install. Variations of suitable battery packs

However, the circuit structure is relatively complicated, requiring the same number of power switches, selector switches, power diodes, and electrolytic capacitors as the number of single cells, so the cost is very high

Moreover, the circuit can only transfer energy to one single battery or several adjacent batteries at the same time through the selection switch, so it cannot balance any number of batteries, and the equalization efficiency is low

In addition, the final equalization effect of the equalization circuit cannot make the electric energy fully charged, and additional control is required to charge the battery pack

[0007] To sum up, the passive equalization circuit in the prior art not only consumes precious energy, but also causes many problems such as system heating.

Active equalization requires multiple high-speed power switching devices, high cost, complex control, heat dissipation, cannot balance multiple arbitrary single cells at the same time, and low equalization efficiency

In addition, some circuits cannot replenish the energy of the battery pack through equalization to fully charge the battery.

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