CN-121461534-B - Battery pack voltage balance control system and method and battery pack

CN121461534BCN 121461534 BCN121461534 BCN 121461534BCN-121461534-B

Abstract

The invention discloses a battery pack voltage balance control system and method and a battery pack, wherein the control method comprises a charge balance control process and/or a discharge balance control process, the charge balance control process comprises the steps of detecting the voltage of each battery module to obtain the battery module with the highest voltage, controlling a bypass of the battery module with the highest voltage and controlling the rest battery modules to continue to dynamically balance charge, the discharge balance control process comprises the steps of detecting the voltage of each battery module in a discharge state to obtain the battery module with the highest voltage, controlling the battery module with the highest voltage to increase the discharge current of a battery cell to discharge and controlling the battery cells of the rest battery modules to dynamically balance discharge with normal discharge current.

Inventors

LU PENG
TIAN YUANBO
ZOU QUANFU

Assignees

惠州市乐亿通科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260105

Claims (7)

1. A battery pack voltage balance control method is characterized by comprising a charge balance control process and/or a discharge balance control process, wherein, The charge balance control process comprises the following steps: Detecting the voltage of each battery module to obtain the battery module with the highest voltage; Controlling a battery module bypass with the highest voltage and controlling the rest battery modules to continue dynamic equalizing charge; the discharge balance control process comprises the following steps: detecting the voltage of each battery module in a discharging state, and obtaining the battery module with the highest voltage; Controlling the battery module with the highest voltage to increase the discharge current of the battery cells to discharge, and controlling the battery cells of the rest battery modules to dynamically and uniformly discharge at the normal discharge current; Detecting the voltage of each battery module in a charging state in the charge balance control process, wherein the charge balance control process comprises the steps of detecting the voltage of all battery modules in a battery pack to obtain the battery module with the highest voltage at first in initial charge, detecting the voltage of the battery module in a bypass state and the voltage of all other battery modules which continue to charge at intervals of a preset first interval time, and obtaining the battery module with the highest voltage in the detection after the detection of each round is completed; The dynamic equalizing charge comprises the steps of controlling a battery cell with lower voltage in a battery module to charge when the battery cell is charged, controlling a battery cell with higher voltage in the battery module to suspend charging, controlling the battery cell with higher voltage in the battery module to discharge when the voltages of the two battery cells are equal, controlling the battery cell with higher voltage in the battery module to suspend discharging when the voltages of the two battery cells are equal, enabling the discharging current of the battery cell with higher voltage to be equal to half of the load current when the voltages of the two battery cells are equal, and enabling the discharging current of each battery cell to be equal to half of the load current when the voltages of the two battery cells are equal.
2. The control method according to claim 1, wherein detecting the voltage of each battery module in the discharge state during the discharge equalization control includes detecting the battery module having the highest voltage among all the discharged battery modules at every preset second interval time, and knowing the battery module having the highest voltage in the round of detection after each round of detection is completed.
3. A battery pack voltage balance control system is characterized by comprising a main control chip, a plurality of battery modules, a plurality of switch units and a plurality of unidirectional conduction units, wherein each battery module is provided with a charge anode, a charge cathode, a discharge cathode and a discharge anode, the main control chip is electrically connected with the battery modules and the switch units, a switch unit is connected between the charge cathode and the charge anode of each battery module, the discharge cathode and the discharge cathode of each battery module are connected with the unidirectional conduction units, when the main control chip receives a charge signal, the main control chip controls the switch units to be closed, the unidirectional conduction units to be opened, then the main control chip detects the voltage of each battery module to acquire the battery module with the highest voltage, controls the bypass of the battery module with the highest voltage and controls the rest battery modules to be dynamically balanced, when the main control chip receives the discharge signal, the main control chip controls the switch units to be opened, the unidirectional conduction units to detect the voltage of each battery module in a discharge state to acquire the battery module with the highest voltage, and controls the battery modules with the highest voltage to be discharged to perform the normal current balance of the battery cells.
4. The control system of claim 3 wherein when the main control chip receives the charge signal, the main control chip detects the voltages of all the battery modules to obtain the battery module having the highest voltage at first when the main control chip receives the charge signal, and detects the voltages of the battery module in the bypass state and all the remaining battery modules to be charged at a predetermined first interval, and obtains the battery module having the highest voltage in the detection after each detection.
5. The control system of claim 3, wherein the main control chip detects the battery module having the highest voltage among all discharged battery modules every a predetermined second interval time when the main control chip receives the discharge signal, and learns the battery module having the highest voltage in each round of detection after each round of detection is completed.
6. The control system of claim 3, wherein each battery module comprises a switching element, a first unidirectional conducting element, a second unidirectional conducting element, a first battery cell and a second battery cell, one end of the switching element is respectively connected with a charging positive electrode, a positive electrode of the first battery cell and a positive electrode of the second unidirectional conducting element, the other end of the switching element is connected with a charging negative electrode, a negative electrode of the second battery cell and a negative electrode of the first unidirectional conducting element, the switching element is also connected with a main control chip, the negative electrode of the first battery cell is respectively connected with the positive electrode of the first unidirectional conducting element and a discharging negative electrode, the positive electrode of the second battery cell is respectively connected with the negative electrode of the second unidirectional conducting element, wherein when the main control chip receives a charging signal, the switching element in the battery module with the highest voltage is controlled to be closed, so that the battery module with the highest voltage is bypassed, the main control chip also controls the switching element in the rest battery modules, the first battery cell and the second battery cell are connected in parallel, when the main control chip receives a discharging signal, the main control chip knows that the battery with the highest voltage is obtained, the battery module with the first battery cell with the highest voltage is controlled, the second battery cell is controlled to discharge the second battery cell is controlled to be in parallel, and the rest battery module with the highest voltage is normally discharged, and the current in the second battery module is controlled to be discharged.
7. A battery pack comprising the battery pack voltage equalization control system of any of claims 3-6.

Description

Battery pack voltage balance control system and method and battery pack Technical Field The invention relates to the technical field of voltage balance control, in particular to a battery pack voltage balance control system and method and a battery pack. Background With the wide application of lithium ion batteries in the fields of electric automobiles, energy storage systems, portable electronic devices and the like, the performance and the safety of lithium battery packs are increasingly concerned. In practical applications, due to differences in manufacturing process, use environment and aging degree, there is often inconsistency between the voltage and the capacity of each unit cell in the battery pack, namely, a phenomenon of so-called "imbalance of unit voltages". The imbalance phenomenon can directly influence the overall performance of the battery pack, particularly, in the charge and discharge process, a monomer with lower voltage can reach the charge and discharge cut-off voltage in advance, and a monomer with higher voltage can not fully utilize the capacity of the battery pack, so that the overall available capacity of the battery pack is reduced, and a wooden barrel effect is formed. Currently, battery pack equalization techniques are mainly divided into two major categories, passive equalization and active equalization. The passive equalization technology is to realize voltage equalization by connecting energy dissipation resistors in parallel on the battery monomers and dissipating the energy of the monomers with higher voltage in the form of heat. The method has the defects of high energy loss, low equalization speed, equalization in a static state and the like although the structure is simple and the cost is low. Especially, during the dynamic charge and discharge process, the battery pack lacks enough standing time to perform equalization, so that imbalance problems are gradually accumulated, and the service life and energy efficiency of the battery pack are seriously affected. The active equalization technology transfers the energy of the high-voltage monomer to the low-voltage monomer in an energy transfer mode, so that the energy utilization rate is improved. The existing active equalization scheme comprises topological structures such as an inductive type, a capacitive type and a transformer type, but the existing active equalization scheme generally has the problems of complex circuit, high control difficulty, high cost, difficulty in realizing dynamic real-time equalization and the like. Disclosure of Invention Aiming at the defects of the prior art, a battery pack voltage balance control system and method and a battery pack are provided. The invention provides a battery pack uniform control method, which comprises a charge balance control process and/or a discharge balance control process, wherein the charge balance control process comprises the steps of detecting the voltage of each battery module to obtain the battery module with the highest voltage, controlling a bypass of the battery module with the highest voltage and controlling the rest battery modules to continue to dynamically balance charge, the discharge balance control process comprises the steps of detecting the voltage of each battery module in a discharge state to obtain the battery module with the highest voltage, controlling the battery module with the highest voltage to increase the discharge current of a battery cell to discharge and controlling the battery cells of the rest battery modules to dynamically balance discharge with normal discharge current. According to one embodiment of the invention, in the charge balance control process, detecting the voltage of each battery module in a charged state comprises detecting the voltages of all battery modules in a battery pack to obtain the battery module with the highest voltage at the beginning of charge, detecting the voltages of the battery module in a bypass state and all other battery modules continuously charged at preset first interval time intervals, and obtaining the battery module with the highest voltage in the detection after each round of detection. According to one embodiment of the invention, in the discharging balance control process, detecting the voltage of each battery module in a discharging state comprises detecting the battery module with the highest voltage in all discharged battery modules at intervals of a preset second interval, and acquiring the battery module with the highest voltage in the detection after each round of detection is completed. According to one embodiment of the invention, the dynamic equalizing charge comprises controlling the charging of the battery cells with lower voltage in the battery module when charging, and suspending the charging of the battery cells with higher voltage in the battery module, when the voltages of the two battery cells are equal, the two battery cells are charged simultaneously. According to one emb