Series lithium battery pack voltage balancing device and control method

Abstract

The invention discloses a series lithium battery pack voltage balancing device and a control method, the series lithium battery pack voltage balancing device is used for a battery pack Pack1 and a battery pack Pack2 which are connected in series, two ends of a capacitor C1 are connected to two ends of the battery pack Pack1 and the battery pack Pack2 which are connected in series, one end of a first switch S1 is connected with one end of the capacitor C1, the other end of the first switch S1 is connected with one end of a first inductor L1 and an anode of a first diode D1, and the other end of the first inductor L1 is connected with the anode of a second diode D1. The other end of the first inductor L1 is connected to the joint of the battery pack Pack1 and the battery pack Pack2, one end of the second switch S2 is connected with one end of the second inductor L2 and the cathode of the second diode D2, the other end of the second switch S2 is connected with the other end of the capacitor C1, the anode of the second diode D2 is connected with one end of the capacitor C1, and the other end of the second diode D2 is connected with the other end of the capacitor C1. The other end of the second inductor L2 is connected to the joint of the battery pack Pack1 and the battery pack Pack2, and the duty ratio of the first switch S1 and the duty ratio of the second switch S2 are controlled through a controller. Energy conversion in the series battery pack can be achieved, and the purpose of balancing the series battery pack is achieved.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, and more particularly, to a voltage balancing device and a control method of a series-connected lithium battery pack. Background technique [0002] With the wide application of power batteries and energy storage batteries, battery packs packaged into modules often need to be connected in series to increase the voltage and system capacity. Due to the inconsistency of the cells, the battery packs connected in series usually have inconsistent battery packs after a period of use. Since the battery pack is managed by the BMS, considering the protection of the battery, the BMS will perform low-voltage protection for battery pack discharge and high-voltage protection for charging. When the battery pack is inconsistent, when charging, the BMS will use the relatively high-voltage battery pack as the protection object; and when discharging, the BMS will use the relatively low-voltage battery pac...

AI Technical Summary

Problems solved by technology

In addition, the resistor itself will continue to consume the energy of the battery, which is not an optimal solution for the battery itself.

[0004] In addition, the existing technology also uses inductors and switches for energy transition, but due to the design of the circuit, it is necessary to adjust the switch on the basis of a relatively large occupation ratio (such as 50%)

This adjustment method will make the current ripple on the inductor larger. Considering that the switch also has loss, the loss of the switch will also increase when the current is large.

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