A constant voltage circuit of series battery cells and its control method

Abstract

The invention discloses a constant voltage circuit of series-connected battery cells, including batteries and a DC power supply. A battery constant voltage unit is connected in parallel at both ends of each battery, and all battery constant voltage units are connected to a state-controlled constant voltage unit. On the control unit, the feedback positive terminal of each battery constant voltage unit is connected to the positive terminal of the DC power input, and the feedback negative terminal of each constant voltage unit is connected to the negative terminal of the DC power input. The control unit controls the state of the constant voltage unit. The overall constant current charge and discharge step, and also realize the constant voltage charging step for a single battery; in addition, during the single battery constant voltage step, the excess energy is fed back to the DC power supply process. The invention also discloses a control method of the constant voltage circuit of the battery cells connected in series. The invention can realize the constant current charging and discharging step of the whole battery under the state of the batteries being connected in series, and simultaneously realize the constant voltage charging step of the single battery.

Description

technical field [0001] The invention relates to the technical field of battery charge-discharge control circuits, in particular to a constant voltage circuit of series-connected battery cells and a control method thereof. Background technique [0002] In the lithium battery formation / capacity division process, the battery needs to be charged / discharged with a constant current first. When the battery is charged / discharged with a constant current to a certain voltage, the battery needs to be charged / discharged with a constant voltage. [0003] At present, the conventional solution is to charge / discharge a battery with constant current and constant voltage for one channel, but due to the differences between different channels, it is easy to cause battery consistency problems. It was then proposed to connect the batteries in series and use the same channel to charge / discharge them. [0004] Because after the batteries are connected in series, when the batteries are charged / disc...

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Problems solved by technology

[0004] Because after the batteries are connected in series, when the battery is charged / discharged, the current flowing through each battery should be equal, but due to the difference of the batteries, this will cause some batteries to enter the constant voltage step first, and others The battery is still in the constant current step. After entering the constant voltage step, the current flowing through the battery will decrease, while the current of the battery in the constant current step will remain unchanged, which creates a contradiction.

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