KR100720820B1 - Method of Improving the Performance of Battery Module by Leveling Voltage and Parallel Connecting Device Therefore - Google Patents

Abstract

The present invention provides a battery module in which two or more unit cells are connected in series, and the unit cells are interconnected in parallel during the manufacturing of the battery module or during use of the battery module. It provides a method of improving the performance of the battery module by minimizing the voltage difference between them, and a parallel connection device that can effectively perform such a method.

Description

Method for Improving Battery Module Performance by Voltage Leveling and Parallel Connection Device {Method of Improving the Performance of Battery Module by Leveling Voltage and Parallel Connecting Device Therefore}

1 is a block diagram for leveling the voltage of the unit cells of the battery module according to the present invention;

2 is a graph showing the results of experiments of voltage leveling on seven unit cells in accordance with the present invention;

3 is a perspective view of a parallel connection device for voltage leveling according to an embodiment of the present invention;

4 is a perspective view of one exemplary battery module capable of effectively performing voltage leveling using the parallel connection of FIG. 3;

5 and 6 are diagrams illustrating connection states of electrode terminals in the battery module of FIG. 3.

<Description of Major Symbols in Drawing>

100: battery module 200: unit battery

300: parallel connection device 400: first circuit portion

400: second circuit portion 500: third circuit portion

600: printed circuit board 700: insulating member

800: connecting member 900: fuse

The present invention provides a battery module in which two or more unit cells are connected in series, and is connected between the unit cells in parallel before the series connection at the time of manufacturing the battery module or during use of the battery module, thereby leveling (leveling) the voltages between the unit cells. The present invention relates to a method of improving the performance of a battery module by minimizing a voltage difference and a parallel connection device capable of performing the method effectively.

Recently, secondary batteries capable of charging and discharging have been widely used as energy sources of wireless mobile devices. In addition, secondary batteries are attracting attention as energy sources such as electric vehicles and hybrid electric vehicles, which are proposed as a way to solve air pollution of conventional gasoline and diesel vehicles using fossil fuel. Therefore, the type of applications using the secondary battery is very diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products from now on.

As the application fields and products of secondary batteries are diversified as described above, the types of batteries are also diversified to provide outputs and capacities suitable for them, and batteries applied to the fields and products are required to be light in size and weight. .

For example, small mobile devices such as mobile phones, PDAs, digital cameras, notebook computers, and the like are used with one or two or four small and light battery cells per device according to the miniaturization tendency of the products. On the other hand, medium and large devices such as electric bicycles, electric motorcycles, electric vehicles, hybrid electric vehicles, etc., due to the necessity of high output capacity, medium and large battery modules (or battery packs) electrically connecting a plurality of battery cells are used.

As such, the medium-large secondary battery module including a plurality of battery cells (unit cells) is particularly connected to all or at least a portion of the unit cells in series to provide a high output. The unit cells are preferably composed of cells of the same capacity and voltage standard. However, despite these same specifications, due to manufacturing limitations due to various factors, it is common for unit cells to actually exhibit voltage differences. When the unit cells constituting the battery module have such a voltage difference, the performance of the battery module is degraded. In addition, the voltage difference between the unit cells may occur due to various factors as well as in the case of manufacturing the battery module as well as the use of the battery module.

Therefore, there is a high demand for a technology capable of maintaining the operating state of the battery module in the best state by minimizing the voltage difference between the unit cells.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

The inventors have conducted in-depth research and various experiments, and when the battery cells are connected in parallel for a predetermined time during the manufacture or use of a battery module composed of a plurality of unit cells, the voltage difference between the unit cells is minimized. It has been found that can maintain the performance of the best. In addition, a new parallel connection device has been developed that can effectively perform such voltage leveling.

Accordingly, the method of improving the performance of a battery module according to the present invention includes two or more of the unit cells connected in series in a battery module including a plurality of unit cells for a predetermined time during manufacture or use of the battery module. And interconnecting in a parallel manner to minimize voltage differences between the unit cells by leveling the voltages of the unit cells.

The battery module of the present invention is a medium or large battery module that provides a high output large capacity because all or part of two or more unit cells are connected in series. Therefore, the unit cells connected in series are temporarily connected in parallel during manufacturing or use of the battery module, thereby minimizing a voltage difference between the unit cells, thereby optimizing an operating state of the battery module.

The unit cells are not particularly limited as long as they are secondary batteries capable of charging and discharging. Preferably, a lithium secondary battery using lithium transition metal oxide or composite oxide as a cathode active material may be used. In addition, the form of the unit cell is not particularly limited, and pouch-type cells and square cells, which can be charged with high density, are more preferable.

The number of unit cells constituting the battery module may vary depending on the desired capacity and output, and the connection method of these unit cells may also be in series or parallel and parallel connection.

In the present invention, at least two or more of two or more unit cells connected in series are temporarily connected to each other to level (level) the voltage of the unit cells. Preferably, the voltage of all the unit cells connected in series may be leveled, and in the combined connection method, the voltage of all the unit cells may be leveled.

The predetermined time for performing the parallel connection may vary depending on various factors such as the number of unit cells, the voltage, the capacity, and the leveling level of the desired voltage. In one preferred example, the parallel connection time can be set such that the voltage of each of the cells leveled as a result of voltage leveling matches up to a unit of 0.001 V.

The voltage leveling according to the invention can be done at any time during the manufacture or use of the battery module. In manufacturing the battery module, it is preferable to perform prior to series connection of the unit cells.

The present invention also provides a parallel connection device for voltage leveling that can effectively perform the voltage leveling.

The parallel connection device for voltage leveling according to the present invention comprises a connection device for a positive electrode terminal and a connection device for a negative electrode terminal, wherein each connection device includes conductive connection members connected to positive or negative terminals of unit cells. The connecting members consist of electrical interconnections.

In one preferred example, the connecting members are arranged in a line in a state of being electrically connected with each other as a conductive member of a plate-like strip, and are attached on an insulating body, and a wire as another connecting member is electrically connected to the connecting members. Is coupled to the insulating body in a state.

Such a parallel connection device can be effectively used for voltage leveling of a battery module in which a plurality of unit cells are sequentially stacked. Since the electrode terminals of the unit cells sequentially stacked are arranged at regular intervals, it is possible to connect the connection members of the same arrangement at once.

A preferred example of such a battery module capable of such efficient voltage leveling is the battery module of Korean Patent Application No. 2004-112589 of the applicant, which is incorporated by reference in the context of the present invention.

Hereinafter, the content of the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

1 is a structural diagram for leveling the unit cell voltage of the battery module according to the present invention.

Referring to FIG. 1, the battery module 100 includes a plurality of unit cells 200, 201, 202... 209 capable of charging and discharging, and each of the unit cells 200, 201, 202. It is connected in series to provide high power. In FIG. 1, it can be seen that the electrical connection state between the unit cells 200, 201, 202... 209 is released for voltage leveling. In this electrical disconnection state, the positive terminals 210, 211, 212 ... 219 and the negative terminals 220, 221, 222 ... 229 of each of the unit cells 200, 201, 202. Voltage leveling is performed by connecting each of them in parallel.

2 shows a graph showing the results of experiments with voltage leveling in this manner.

Voltage leveling was performed for all seven unit cells by parallel connection for about 7000 seconds. Unit cells used were randomly selected from a number of lithium secondary batteries (LG Chem .: E1 ^TM ). As shown in the graph of FIG. 2, a plurality of unit cells exhibit an initial voltage in a range of 4.150 V to 4.160 V, while some unit cells exhibit an initial voltage in a range of 4.130 V to 4.140 V, thereby reducing the number of unit cells. The voltage difference was approximately 0.030 V. However, when the parallel voltage leveling according to the present invention is performed, it can be seen that as time passes, these unit cells converge to a leveled voltage of about 4.147 to 4.148 V, respectively. Therefore, over time, all unit cells are regulated to a leveled voltage, and when unit cells are connected in series in such a state, the battery module is electrically connected to an optimal state for operation.

3 is a perspective view of a parallel connection device for voltage leveling according to an embodiment of the present invention.

Referring to FIG. 3, the voltage leveling parallel connection device 300 includes a positive terminal connection device 301 and a negative terminal connection device 302. The two connecting devices 301 and 302 have substantially the same shape, and a plurality of connecting members 320 are attached to the electrically insulating main body 310, and one wire 330 is connected thereto. The connecting members 320 have a plate-like strip structure and are spaced apart at regular intervals and are electrically connected to each other. The wire 330 has a connection cord 332 at one end and the other end is connected to the main body 310. As another connecting member, the wire 330 is also electrically connected to the connecting members 320. The positive electrode terminal connecting device 301 and the negative electrode terminal connecting device 302 may be manufactured in a completely separate structure as shown in FIG. 3, but in some cases, may be manufactured in a structure capable of being separated from each other and assembled. have. Even in the latter case, the positive electrode terminal and the negative electrode terminal are electrically insulated.

4 is a perspective view of one exemplary battery module capable of effectively performing voltage leveling using the parallel connection device of FIG. 3, and FIG. 5 and FIG. 6 show an electrode terminal connection state diagram of such a battery module. have.

First, referring to FIG. 4, the battery module 100 includes an upper case 110, a lower case 120, a plurality of unit cells 200, a first circuit unit 400, a second circuit unit 500, and a first circuit unit. Three circuit parts 600 are included. The unit cells 200 are stacked between the upper case 110 and the lower case 120 which are separated from each other, the first circuit unit 400 is located in front of the battery module 100, the second circuit unit 500 ) Is located at the bottom, and the third circuit unit 600 is located at the back.

Since the upper case 110 and the lower case 120 are separated, the number of unit cells 200 that can be stacked is not limited thereto, and according to the number of stacked units of the unit cells 200, the first circuit unit 400 is used. ) And only the third circuit unit 600, it is possible to easily design the battery module 100 of the desired capacitance and output. In addition, since the unit cells 200 are exposed, heat dissipation of the unit cells 200 may be efficiently performed during charging and discharging.

The first circuit unit 400 is attached to the electrode terminal direction of the unit cell 200. The first circuit unit 400 includes a sensing board assembly for connecting the unit cells 200 in series and detecting voltage, potential, temperature, and the like from each unit cell 200.

The unit cells 200 are electrically connected to the second circuit unit 500 mounted at the bottom of the lower case 120 via the first circuit unit 400, and the operation of the battery module is performed by the second circuit unit 500. Is controlled from the motherboard assembly.

On the opposite side of the battery module 100 on which the first circuit unit 400 is mounted, a third circuit unit 600 electrically connected to the second circuit unit 500 is mounted, and the third circuit unit 600 is a battery. The final element of the battery module 100 that controls the overcharge, overdischarge, overcurrent and the like and is connected to an external device (not shown). Control of overcharge, overdischarge, overcurrent, etc. can be performed by a switching element (not shown), such as a FET included in the third circuit portion 600.

The battery module 100 may be used as a power source for various fields and products such as a power source of a vehicle such as an electric bicycle, an electric motorcycle, an electric vehicle, a hybrid electric vehicle, and other industrial or household devices, and is compact and lightweight The structure makes it particularly preferable to use as a power source for electric bicycles.

An electrical connection state of the unit cells 200 in the first circuit unit 400 will be described with reference to FIG. 5.

The unit cells 200 and 201 are electrically connected by the insulating member 700 and the connecting member 800 having a specific structure. Specifically, each of the coupling parts 830 and 840 of the first terminal connector 810 and the second terminal connector 820 of the connecting member 800 is an indentation of the second assembly unit 740 of the insulating member. 743 is coupled to be inserted. The first terminal connector 810 is inserted into the indentation 743 with the coupling part 830 upright, and the plate-shaped body 814 is the first assembly unit 730 and the second assembly unit ( 740 is coupled to surround the bottom surface. In the process of coupling the first terminal connector 810, the side bent portion 831 of the coupling portion 830 is introduced along the lower guide groove 745 formed long at the bottom of the indentation 743. The first terminal connector 810 is formed of another insulating member (not shown) in which the protrusion is not formed, with its engaging portion 830 inserted into the indentation 743 of the insulating member 700. The coupling groove 812 is made of a closed type because it is mounted on the bottom surface.

On the other hand, the second terminal connector 820 is inserted into the indentation 743 with the coupling portion 840 inverted downward, and the plate-shaped body 824 is the top surface of the second assembly unit 740. It is combined to surround. In the coupling process of the second terminal connector 820, the side bent portion 841 of the coupling portion 840 is introduced along the upper guide groove 744 formed long on the upper end of the indentation 743. The second terminal connector 820 has an upper surface of the insulating member 700 having a protrusion 712 formed therein with its coupling part 840 inserted laterally into the indentation 743 of the insulating member 700. The coupling groove 822 is made to be open because it is mounted on.

The two terminal connectors 810 and 820 remain separated from each other, as shown in the figure (shown before coupling) even when coupled to the insulating member 700. The first terminal connector 810 is connected to the positive terminal 221 of the unit cell 201 fastened to the bottom surface of the first assembly unit 730, and the second terminal connector 820 is the second assembly unit. It is connected to the negative terminal 230 of the unit cell 200 fastened to the protrusion 712 of the (740).

An example of the assembly process is as follows.

The second terminal connector 820 is coupled to the second assembly unit 740 (S1). Then, the first terminal connector 810 is coupled to the second assembly unit 740 (S2). As described above, the coupling groove 822 of the second terminal connector 820 coupled to the second assembly unit 740 matches the through hole 240 of the negative electrode terminal 230 of the unit cell 200 (S3). ). Then, the first assembly unit 730 is coupled to the second assembly unit 740 (S4). Finally, the unit cell 200 is connected to the insulating member so that the through hole 240 of the positive electrode terminal 220 is fastened to the protrusion 710 and the through hole 240 of the negative electrode terminal 230 is fastened to the protrusion 712. It is mounted at 700 (S5). At this time, the positive electrode terminal 220 is in contact with another first terminal connector (not shown) to be coupled thereon while being fastened to the protrusion 710, while the negative terminal 230 is a protrusion 712 Contact with the second terminal connector 820 fastened to FIG.

One example of the assembly process has been described above, and the assembly order may be changed in part. For example, a process (S4) of combining the first assembly unit 710 and the second assembly unit 720 may be performed first.

FIG. 6 schematically illustrates a process of connecting a sensing board (a type of printed circuit board) constituting the first circuit unit 400 of FIG. 4 after assembly in FIG. 5. For the convenience of understanding, only the connecting member which couples the electrode terminals of the unit cell is shown as a partial perspective view.

The printed circuit board 410 is a rectangular plate-like structure, in which a wide opening 411 is formed at the center thereof, and a plurality of drilling tools 412 are formed at one side thereof. Each of the drilling tools 412 is connected to a circuit (not shown) printed on the substrate 413, which is connected to a socket 415 formed at one end of the substrate 413. . The socket 415 may be appropriately determined depending on the number of circuits that may be connected to it. In the upper left and the lower right, bores 416 and 417 of slightly larger sizes are formed to connect the final positive electrode terminal and the negative electrode terminal in series connection of unit cells (not shown), respectively. That is, the drilling tool (416, 417) is connected to the final positive wiring and the negative wiring which makes the electrical connection in the unit cells of the series system.

The opening 411 is formed to open the connection portion of the unit cell electrode terminals positioned on the opposite side of the substrate 413. The opening 411 is a fuse, bimetal, PTC, etc. in the electrode terminal portion in the state where the printed circuit board 410 is mounted. The safety device can be mounted through the opening (411).

As described with reference to FIG. 5, the extension connecting portion 815 of the first terminal connector 810 is oriented toward the printed circuit board 410 while being coupled to the insulating member. Since the first terminal connector 810 is stably fixed to a corresponding position of the electrode terminals of the unit cell, the extension connectors 815 are also positioned. Thus, by placing the printed circuit board 410 on the connecting member 800 so that the drilling tools 412 of the printed circuit board 410 can be inserted into the extension connectors 815, the first step of assembly is performed. can do. The upper end of the extension connecting portion 815 after such mounting protrudes from the substrate 414 through the drilling tool 412, and the electrical connection and physical connection of the connecting member 800 and the printed circuit board 410 by soldering such protrusions The bond is made.

Even after the connecting member 800 and the printed circuit board 410 are coupled, the first terminal connector 810 and the second terminal connector 820 of the connecting member 800 are separated from each other to maintain an insulating state. Therefore, after the assembling of the related elements is completed, they may be energized only by connecting them 810 and 820 with safety elements or separate conductive members. 6 shows a process of making an electrical connection using a fuse 900, which is a kind of safety device, and FIG. 4 shows the overall structure of the battery module 100 in which the electrical connection is made by the fuse 900. Referring to FIG. have.

That is, elastic coupling grooves 833 and 843 are formed in the coupling portions 830 and 840 of the first terminal connector 810 and the second terminal connector 820 while being coupled to the insulating member, and the fuse ( Electrical connection may be made by inserting the connection terminals 920 and 930 of the 900 into the connection grooves 833 and 843 of the coupling units 830 and 840.

Accordingly, the first terminal connector 810 and the second terminal connector 820 are respectively connected to the positive terminal connector 301 and the negative terminal connector 302 of FIG. 3 without the fuse 900 installed. Voltage leveling can be performed by connecting to the coupling portions 830 and 840. Specifically, the connecting members 320 of the plate strips arranged in a line are inserted into the connecting grooves 833 and 843, and the socket 332 of the wire 330 is connected to the final electrode terminal connecting portion (230, 240 in FIG. 4). ) Can be connected in parallel to the positive and negative terminals. Connection terminals 320 of FIG. 2 are connected to the first terminal connector 810 and the second terminal connector 820 electrically connected to the positive terminal and the negative terminal of the unit cell (not shown). Since they are spaced apart at the same interval as the arrangement, connection can be made by one mounting process, and parallel connection can be easily performed by connecting only the final electrode terminal connecting portions 230 and 240 separated by wires 330. have.

In addition, in the battery module 100 of FIG. 4, since the electrode terminals of the unit cells 200 are electrically connected to each other by the fuse 900, when the voltage leveling is to be performed while the battery module 100 is in use, the fuse 900 may be used. By removing the), the electrical connection state of the unit cells 200 is released and the parallel connection device 300 of FIG. 3 is connected instead, so that the voltage leveling of the battery module 100 in use is very easy.

Although the present invention has been described above with reference to the drawings according to embodiments of the present invention, those skilled in the art to which the present invention pertains to various applications and modifications within the scope of the present invention based on the above contents. It will be possible.

As described above, according to the method of the present invention, it is possible to minimize the voltage difference by setting the voltage level by parallel connection to the unit cells constituting the battery module and ultimately set the operation of the battery module to an optimal state. . Such voltage leveling may be optionally performed before the series connection to the electrode terminals or during the use of the battery module. In addition, the parallel connection device according to the present invention has an effect of easily performing voltage leveling in a battery module in which a plurality of batteries are constantly charged.

Therefore, the battery module of the present invention may be variously applied to medium and large battery modules such as an electric bicycle, an electric vehicle, a hybrid electric vehicle, and the like.

Claims (8)

By leveling the voltage of the unit cells by interconnecting two or more of the unit cells connected in series in a battery module including a plurality of unit cells in a parallel manner for a predetermined time during manufacture or use of the battery module. A method for improving the performance of a battery module, comprising the step of minimizing mutual voltage difference. The method of claim 1, wherein the voltages of all unit cells connected in series are leveled, or the voltages of all unit cells are leveled in series / parallel connection. 2. The method of claim 1, wherein the parallel connection time is set such that the voltage of each of the batteries leveled as a result of voltage leveling matches up to a unit of 0.001 V. The method of claim 1, wherein the voltage leveling is performed prior to series connection of the unit cells when the battery module is manufactured. And a connecting device for a positive electrode terminal and a connecting device for a negative electrode terminal, each connecting device including conductive connecting members connected to the positive or negative terminals of the unit cells, the connecting members being mutually conductive members of a plate-like strip. A parallel connection device for performing the voltage leveling according to claim 1, which is arranged in a line in an electrically connected state and is attached on an insulating body. 6. The parallel connection device according to claim 5, wherein a wire as another connection member is coupled to said insulating body in an electrically connected state to said connection members. The method of claim 5, wherein the parallel connection device, A plurality of unit cells which are rechargeable batteries capable of charging and discharging; A rectangular lower case including a lower accommodating part to which the main board assembly is attached and an upper accommodating part to sequentially stack the unit cells; A rectangular upper case including a lower accommodating part covering an upper end of unit cells stacked on the lower case; A first circuit unit including the sensing board assembly capable of performing series connection of stacked unit cells and detecting voltage, current, temperature, etc. of the battery; A second circuit portion electrically connected to the first circuit portion and including a main board assembly for overall control of the pack; And A third circuit portion electrically connected to the second circuit portion and including a switching element that controls operation of the battery during abnormal operation of the battery, such as overcharge, overdischarge, overcurrent, and overheat; Parallel connection device, characterized in that used in the voltage leveling of the medium-large secondary battery module. [8] The parallel connection of claim 7, wherein a fuse is mounted at an electrical connection between the unit cells in the first circuit unit, and the voltage leveling is performed by parallel connection to the corresponding site before or after the fuse is mounted. Device.

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