Bidirectional balanced circuit of power battery pack

Abstract

The invention discloses a bidirectional balanced circuit of a power battery pack, which is applied to a serially-connected battery pack. The bidirectional balanced circuit comprises a DC / DC (Direct Current / Direct Current) conversion circuit, an equalizer switch circuit and an MCU (Microprogrammed Control Unit) microprocessor, wherein the input end of the DC / DC conversion circuit is connected with two ends of the serially-connected battery pack; the output end of the DC / DC conversion circuit is connected with a constant-current circuit; the output end of the constant-current circuit is connected two ends of single battery of the serially-connected battery pack through the equalizer switch circuit; and the MCU microprocessor is respectively connected with the serially-connected battery pack, the equalizer switch circuit and the DC / DC conversion circuit. According to the invention, the constant-current circuit is additionally arranged at the output end of the DC / DC conversion circuit so that the constancy of the equalized current is assured and the condition of damaging the single battery due to the large current is avoided; furthermore, under the control of the MCU microprocessor, the bidirectional equalization of the serially-connected battery pack is realized, and the effects of preventing all the single batteries from over-charging and fully charging all the single batteries are assured on the base of not increasing the charging time, so that the bidirectional balanced circuit of the power battery pack can be widely applied to a BMS (Battery Management System) system of the power battery.

Description

technical field [0001] The invention relates to a battery management system for a power battery pack, in particular to a bidirectional balancing circuit for a power battery pack. Background technique [0002] Due to the large energy consumption of products such as electric vehicles and uninterruptible power systems, in order to avoid excessive current, the application of batteries in series and parallel has become a common phenomenon. A series lithium-ion battery pack is composed of two or more batteries connected in series. In this configuration, the battery voltage is equal to the sum of the individual battery voltages. After adding the load, that is, during the discharge process of the battery pack, the load current is provided by all the batteries connected in series. If the battery is charged, the charger needs to provide charging current to the battery pack connected in series. In both cases, the discharge and charge currents are the same for all cells. Over a life...

AI Technical Summary

Problems solved by technology

[0022] The output current of the digital operational amplifier is very limited, and the relative battery balancing effect is not very ideal; in addition, if only the voltage division of the resistor is used to determine the state of the battery balancing, it is not accurate enough.

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