WO2011157116A1

WO2011157116A1 - Lithium battery module parallel using method and system

Info

Publication number: WO2011157116A1
Application number: PCT/CN2011/074912
Authority: WO
Inventors: 水伟; 刘新宇; 刘伟
Original assignee: 华为技术有限公司
Priority date: 2010-12-31
Filing date: 2011-05-30
Publication date: 2011-12-22
Also published as: CN102082307B; CN102082307A

Abstract

A lithium battery module parallel using method and system are provided. The method comprises: collecting a voltage value of each lithium battery module when initially electrifying (S1); based on information collected, controlling a voltage difference between the lithium battery module and the bus in accordance with a voltage sharing mode and orderly inserting the lithium battery module with a minimal voltage difference into the bus (S2); charging or discharging the lithium battery module after the lithium battery module is inserted into the bus (S3). The method can maintain the voltage difference of the lithium battery module in a certain range for inserting the module in a parallel manner, reduce the voltage difference in the interior-group, avoid high current impact between the battery groups, reduce damages of the battery management system (BMS) circuit, and improve the safety of the lithium battery module by using parallelly.

Description

Method and system for parallel use of lithium battery module This application claims priority to Chinese patent application filed on December 31, 2010, the Chinese Patent Office, Application No. 20101 0620101. 0, the invention titled "Liquid Battery Module Parallel Use Method and System", The entire contents of this application are incorporated herein by reference.

Technical field

The invention relates to a method and a system for parallel use of lithium battery modules. Background technique

Lithium batteries have high energy density, high single cell voltage, long life, no memory effect, and no pollution. Therefore, the use of lithium battery power supply is the development trend of battery applications. In high-power applications, the battery cells are first connected in series to form a battery pack to increase the supply voltage, and then the battery packs are connected in parallel to increase the output power of the power supply. Both the single cell and the battery pack in series require a Battery Management System (BMS) monitoring management. The lithium battery pack and the BMS together form a lithium battery module.

The main problem with the parallel use of lithium battery modules is the large current surge between groups. Since the voltages of the battery packs are different and directly connected in parallel, there is a process of voltage balance at the convergence point. In the process, by

This can cause damage to the BMS circuit. Summary of the invention

Embodiments of the present invention provide a method and system for parallel use of a lithium battery module, which can reduce damage to the BMS circuit and improve the safety of the lithium battery module in parallel use.

The embodiment of the invention adopts the following technical solutions:

A method for parallel use of a lithium battery pack, comprising:

Collecting voltage values of the respective lithium battery modules at initial power-on;

According to the collected information, the voltage difference between each lithium battery module and the busbar is controlled according to the voltage equalization mode, and the lithium battery module having the smallest voltage difference from the busbar is sequentially connected to the busbar;

The lithium battery modules after accessing the busbar are simultaneously charged and discharged. A system for parallel use of a lithium battery module includes: one or more lithium battery modules and a main control unit; wherein the main control unit is configured to collect voltage values of the lithium battery modules at initial power-on, according to the collected information, according to the voltage equalization The method controls the voltage difference between each lithium battery module and the busbar, and sequentially connects the lithium battery module having the smallest voltage difference with the busbar to the busbar, and then simultaneously connects the lithium battery modules after the busbar is connected Discharge.

According to the above technical solution, the embodiment of the present invention controls the voltage difference between each lithium battery module and the busbar according to the voltage equalization mode, and sequentially connects the lithium battery module with the voltage difference between the busbar and the busbar to the busbar. The voltage difference of each lithium battery module can be kept within a certain range and then connected in parallel to reduce the voltage difference between the battery groups, thereby avoiding large current surge between the battery groups, thereby reducing damage to the BMS circuit and improving the parallel use of the lithium battery modules. safety.

DRAWINGS

The drawings used in the description of the present invention are briefly described below.

1 is a schematic structural diagram of a method for controlling parallel use of a lithium battery module according to an embodiment of the present invention; FIG. 2 is a structural block diagram of a system for controlling parallel use of a lithium battery module according to an embodiment of the present invention; FIG. 3 is a charging equalization method according to Embodiment 1 of the present invention; Schematic diagram of the parallel mode;

4 is a schematic diagram of a parallel mode of discharge voltage equalization according to Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram of a charge and discharge cooperation parallel manner according to Embodiment 3 of the present invention; FIG.

Figure 6 is a schematic diagram of a parallel method of charging current limiting.

detailed description

The technical solutions of the present invention are clearly and completely described below in conjunction with the accompanying drawings and embodiments. Referring to FIG. 1, a method for parallel use of a lithium battery module according to an embodiment of the present invention includes:

511. Collect voltage values of the respective lithium battery modules at the initial power-on.

512. According to the collected information, the voltage difference between each lithium battery module and the busbar is controlled according to the voltage equalization mode, and the lithium battery module having the smallest voltage difference from the busbar is sequentially connected to the busbar.

513. Simultaneously charge and discharge each of the lithium battery modules after accessing the busbar.

Referring to FIG. 2, a lithium battery module parallel use system provided by an embodiment of the present invention includes: one or more The lithium battery module and the main control unit; wherein, the main control unit is configured to collect the voltage values of the lithium battery modules at the initial power-on, and according to the collected information, the voltage difference between the lithium battery modules and the bus bars is controlled according to the voltage equalization mode. And sequentially, the lithium battery module having the smallest voltage difference from the busbar is connected to the busbar, and then the connected lithium battery modules are simultaneously charged and discharged.

Specifically, the lithium battery module parallel use system is mainly composed of a lithium battery module, a main control unit, a system power source, and a load, wherein the lithium battery module is composed of a battery pack and a BMS (battery management system). The functions of each component are as follows:

The lithium battery module (101, 102, 103) is a backup power supply unit in the DC power supply system, which is used to discharge the system when the system is powered off, and keep the system working normally. The lithium battery module consists of a lithium battery pack and a BMS.

Battery Management System BMS (201, 202, 203) is a device for managing lithium battery packs. It is used to detect the voltage and current of lithium battery packs and single cells, to determine abnormal conditions and to perform protection actions. The BMS can exchange information with the main control unit 401 through a communication interface such as serial port/network port/CAN/wireless/dry node/inter-module communication. In the system of the embodiment of the present invention, the BMS can receive the control of the main control unit and perform the action of hooking up to the system power supply.

The lithium battery pack (301, 302, 303) is a device for storing electrical energy, which is formed by connecting a single battery cell in series. Depending on the application scenario, large-capacity cells are connected in series, and small-capacity cells can be connected in parallel and then in series.

The main control unit 401 is a device for performing data calculation and signal control processing, and performs collection of each BMS voltage, calculation of a voltage equalization algorithm, access of alarm data, and output of an alarm signal. The main control unit can be a stand-alone component or it can be stored in the BMS as software.

The system power supply 501 is a DC output power supply unit, and the communication field is generally 48V DC. In the system of the inventive embodiment, the system power supply acts as a device for charging the lithium battery pack and also supplies power to the load. The system power supply can control whether it is discharged externally.

Load 601, which is a general term for electrical equipment, consumes electrical energy. The loads mentioned in this article are all DC powered devices. The busbar 701 is a convergence point of the system power supply, the lithium battery module, and the load.

It can be understood that FIG. 2 only cites the case where three sets of lithium battery modules are connected in parallel. The method and system of the embodiments of the present invention can theoretically support an infinite number of sets of lithium battery modules in parallel.

The working principle of the system in the embodiment of the present invention is as follows: During initial power-on, the main control unit 401 controls the BMS of each lithium battery module to disconnect the lithium battery module from the busbar, and reports the voltage value of the managed lithium battery module to the communication interface. The main control unit, according to the reported result, collects the voltage value of each lithium battery module at the initial power-on, controls the voltage difference between each lithium battery module and the busbar according to the voltage equalization mode, and sequentially connects the busbar with the busbar The lithium battery module with the smallest voltage difference is connected to the busbar, and then the lithium battery modules connected to the busbar are simultaneously charged and discharged.

According to the above technique of the embodiment of the present invention, the voltage difference between each lithium battery module and the busbar is controlled according to the voltage equalization mode, so that the voltage difference of each lithium battery module is maintained within a certain range and then connected in parallel to reduce the battery pack. The voltage difference between the two groups avoids large current surge between the battery packs, thereby reducing the damage to the BMS circuit and improving the safety of the parallel use of the lithium battery modules.

Hereinafter, an embodiment will be described in which the main control unit controls the voltage difference between each lithium battery module and the busbar in a voltage equalization manner.

Embodiment 1: Charging voltage equalization parallel mode

Referring to FIG. 3, FIG. 3 is a schematic diagram of a parallel mode of charging and voltage equalization according to the embodiment, including:

531. Sort the voltage values of the lithium battery modules that are not connected to the busbar from low to high;

532. According to the sorting result, the lithium battery module with the lowest voltage value is connected to the busbar for charging;

533, when the voltage value of the busbar rises to the voltage value of the second lowest lithium battery module, the second low lithium battery module is connected to the busbar for charging;

534, and so on, until all lithium battery modules are plugged into the busbar.

Take the system structure diagram shown in Figure 2 as an example. When the system is powered on initially, the system power supply works. The BMS of all lithium battery modules disconnects the lithium battery module from the busbar, and is in a state of restlessness. At this time, the initial voltage value of the busbar is zero. Each BMS detects the voltage value of the lithium battery module it manages and reports it to the main control unit. The main control unit compares the voltage values of the lithium battery modules and sorts them. The BMS of the lowest lithium battery module (for example, 101) is connected to the busbar, and the lithium battery pack 301 is charged by the system power supply, and when the busbar voltage rises to the voltage value of the second lowest lithium battery module (for example, 102), The BMS of the second set of lithium battery modules is notified to be connected to the busbar, the lithium battery pack 302 is charged by the system power supply, and so on, until all the lithium battery modules are connected to the busbar.

Embodiment 2: Parallel mode of discharge voltage equalization

Referring to FIG. 4, FIG. 4 is a schematic diagram of a parallel mode of discharge voltage equalization according to the embodiment, including:

541. Sort the voltage values of the lithium battery modules that are not connected to the busbar from high to low;

542. According to the sorting result, the lithium battery module with the highest voltage value is connected to the busbar for discharging;

543, when the voltage value of the busbar drops to the voltage value of the second highest lithium battery module, the second high lithium battery module is connected to the busbar for discharging;

544, and so on, until all lithium battery modules are plugged into the busbar. Achieve some small differences. The system structure diagram shown in Figure 1 is still taken as an example. When the system is powered on initially, the system power supply works. The BMS of all lithium battery modules disconnects the lithium battery module from the busbar, and is in a state of restlessness. At this time, the initial voltage value of the busbar is zero. Each BMS detects the voltage value of the lithium battery module managed by the BMS and reports it to the main control unit. The main control unit compares the voltage values of the lithium battery modules and sorts them, first notifying the BMS of the highest voltage lithium battery module (for example, 101) to the busbar. Then, the system power is disconnected, the lithium battery pack 301 is discharged, and when the busbar voltage drops to the voltage value of the second highest lithium battery module (for example, 102), the BMS of the second lithium battery module is notified to the mother. On the top, disconnect the system power to discharge the lithium battery pack 302, and so on, until all the lithium battery modules are connected to the busbar. Then turn on the system power to charge and discharge each lithium battery module in parallel.

Embodiment 3: Charging and discharging voltage equalization parallel mode

Referring to FIG. 5, FIG. 5 is a schematic diagram of a parallel connection mode of charge and discharge voltage equalization according to the embodiment, including:

551. Calculate an average voltage value of voltage values of each lithium battery module that is not connected to the busbar;

552, the lithium battery module whose voltage value is lower than the average voltage value is sequentially connected to the busbar from low to high for charging, until the voltage value of the busbar rises to the average voltage value; S53, the lithium battery module whose voltage value is higher than the average voltage value is sequentially connected to the busbar from high to low for discharging until the voltage value of the busbar falls to the average voltage value.

Specifically, the lithium battery module whose voltage value is lower than the average voltage value is connected to the busbar from the lithium battery module with the lowest voltage value for charging, and when the voltage value of the busbar rises to the voltage value of the second lowest lithium battery module. And charging the second low lithium battery module into the busbar for charging, and so on, until the voltage value of the busbar rises to the average voltage value; and the lithium battery module having a voltage value higher than the average voltage value The lithium battery module with the highest voltage value starts to be connected to the busbar for discharging. When the voltage value of the busbar drops to the voltage value of the second highest lithium battery module, the second high lithium battery module is connected to the busbar for discharging, Such a push until the voltage value of the busbar drops to the average voltage value.

The above steps S52 and S53 have no specific order requirements, and may be performed simultaneously or in any step.

Still taking the system structure diagram shown in Figure 1 as an example, when the system is powered on initially, the system power supply works, and the BMS of all the lithium battery modules disconnects the lithium battery module from the busbar, and is in a state of restlessness. At this time, the initial voltage value of the busbar is zero. Each BMS detects the voltage value of the lithium battery module it manages and reports it to the main control unit. The main control unit compares the voltage values of the lithium battery modules and sorts them to calculate the average voltage value. If the comparison result is: The lithium battery pack 301 voltage value < When the voltage value of the lithium battery pack 302 < average voltage value < the voltage value of the lithium battery pack 303, the lithium battery module 101 having the lowest voltage can be first connected to the busbar, and the lithium battery pack 301 can be charged by the system power source 501, and the busbar is arranged. When the voltage rises to the voltage value of the lithium battery pack 302, the lithium battery module 102 is notified to be connected to the busbar, and the lithium battery pack 302 is charged by the system power supply until the voltage value of the busbar rises to the average voltage value. Then, the highest voltage lithium battery module 103 is notified to be connected to the busbar, and then the system power supply is disconnected, and the lithium battery pack 303 is discharged. When the busbar voltage drops to the average voltage value, the system power supply is turned on in parallel. Each lithium battery module is charged and discharged.

It should be noted that, in the foregoing Embodiments 1 to 3, when the actual logic is controlled, when the voltage difference between the lithium battery pack and the busbar is less than a certain range (the difference range is determined according to the test condition, generally set to ± 0.5V ), then inform the BMS to attach the lithium battery module, and then determine whether the lithium battery module is All hooks are completed. If not all hook complete, the charging or discharging of the battery continues to wait until all the modules are attached to the lithium busbars _fi system is then controlled by the master unit to each power module the access lithium busbar simultaneously charge and discharge.

The main air unit of the embodiment of the present invention described above may be a separate component or may be present as a software function module in the battery management system BMS of each lithium battery module.

Further, in each of the lithium battery modules of the above embodiments of the present invention, a charge current limiting circuit is disposed in the BMS of at least one of the lithium battery modules. As shown in Fig. 6, for the BMS provided with the charge current limiting circuit, the charge and discharge circuits of each BMS are completely independent. Due to the limitation of the charging curve of the lithium battery, the limited current function in the charging circuit, before the parallel connection of the electric modules in the ^!, the BMS is set to the charging state, because of the function of the current limiting, the large current surge can be further avoided. It should be noted that the positive junction point in Figure 6 is only a schematic diagram. In the actual system, it may be a negative current sink, or both the positive and negative poles are converging.

The method and system for controlling the parallel use of the lithium battery modules provided by the embodiments of the present invention can be applied to all scenarios in which the lithium battery modules are connected in parallel.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of this issue. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Claim

A method for parallel use of a lithium battery module, characterized in that it comprises:

The lithium battery modules after accessing the busbar are simultaneously charged and discharged.

2. The method according to claim 1, wherein the collecting the voltage values of the respective lithium battery modules at the initial power-on comprises:

At the initial power-on, the battery management system of each lithium battery module disconnects the lithium battery module from the busbar, and reports the voltage value of the managed lithium battery module through the communication interface;

According to the reported result of the battery management system of each of the lithium battery modules, the voltage values of the respective lithium battery modules at the time of initial power-on are collected.

The method according to claim 2, wherein the communication interface is any one of the following: a serial port, a network port, a CAN, a wireless, a dry node, or an inter-module communication interface.

The method according to claim 1, wherein the voltage difference between each lithium battery module and the busbar is controlled according to the collected information, and the voltage between the busbar and the busbar is sequentially The lithium battery module with the smallest difference is connected to the busbar:

Sorting the voltage values of the lithium battery modules that are not connected to the busbar from low to high;

According to the sorting result, the lithium battery module with the lowest voltage value is connected to the busbar for charging;

When the voltage value of the busbar rises to the voltage value of the second lowest lithium battery module, the second low lithium battery module is connected to the busbar for charging;

And so on, until all lithium battery modules are connected to the busbar.

Sorting the voltage values of the lithium battery modules that are not connected to the busbar from high to low; According to the sorting result, the lithium battery module with the highest voltage value is connected to the busbar for discharging;

When the voltage value of the busbar drops to the voltage value of the second highest lithium battery module, the second high lithium battery module is connected to the busbar for discharging;

And so on, until all lithium battery modules are connected to the busbar.

Calculating an average voltage value of voltage values of each lithium battery module that is not connected to the busbar;

And charging the lithium battery module whose voltage value is lower than the average voltage value into the busbar from low to high for charging until the voltage value of the busbar rises to the average voltage value;

The lithium battery modules having a voltage value higher than the average voltage value are sequentially connected to the busbar from high to low for discharging until the voltage value of the busbar drops to the average voltage value.

7. The method of claim 6 wherein:

And charging the lithium battery module whose voltage value is lower than the average voltage value into the busbar from low to high for charging until the voltage value of the busbar rises to the average voltage value comprises:

The lithium battery module with the lowest voltage value is connected to the busbar for charging. When the voltage value of the busbar rises to the voltage value of the second lowest lithium battery module, the second low lithium battery module is connected to the busbar for charging, Such a push until the voltage value of the busbar rises to the average voltage value;

The lithium battery module having a voltage value higher than the average voltage value is sequentially connected to the busbar from high to low for discharging, until the voltage value of the busbar drops to the average voltage value, including:

Discharging the lithium battery module with the highest voltage value into the busbar for discharging. When the voltage value of the busbar drops to the voltage value of the second highest lithium battery module, the second high lithium battery module is connected to the busbar for discharging, Such a push until the voltage value of the busbar drops to the average voltage value.

8. A method according to any one of claims 1-7, characterized in that a charging current limiting circuit is provided in the battery management system of at least one of the lithium battery modules.

9. A system in which lithium battery modules are used in parallel, characterized in that it comprises: one or more lithium electric modes Block, main control unit;

The main control unit is configured to collect voltage values of the lithium battery modules at the initial power-on, and according to the collected information, control the voltage difference between the lithium battery modules and the busbars according to the voltage equalization mode, and sequentially and the busbars The lithium battery module with the smallest voltage difference is connected to the busbar, and then the lithium battery modules after the busbar are connected are simultaneously charged and discharged.

10. The system according to claim 9, wherein the manner in which the main control unit controls the voltage difference between each of the lithium battery modules and the busbars according to the voltage equalization method comprises any one of the following:

Charge equalization, discharge equalization, or charge and discharge equalization.

The system according to claim 9 or 10, wherein the main control unit is a separate component, or the main control unit is present as a software function module in a battery management system of each lithium battery module.