JP2010268550A - Energy storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy storage device capable of simplifying the wiring of circuits uniformizing voltage in a plurality of power storage elements. <P>SOLUTION: The plurality of power storage elements (11) include positive and negative electrode terminals (11a), (11b) at both the edges in a prescribed direction. The plurality of power storage elements (11) are disposed side by side so that both the edges are positioned in nearly the same surface while being connected in series. Then, a first resistive element (40) is connected in parallel with a first element group comprising 2n (n is an integer hereinafter) power storage elements connected in series. Also, a second resistive element (40) is connected in parallel with a second element group which comprises 2n power storage elements connected in series. In this case, one end of the second resistive element is connected between two power storage elements included in the first element group and connected in series. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power storage device including an equalization circuit that equalizes voltages of a plurality of power storage elements connected in series.

  As shown in FIG. 7, in some battery modules in which a plurality of unit cells (secondary cells) 100 are connected in series, a discharge circuit 200 is connected to each unit cell 100 in parallel. The discharge circuit 200 includes a resistance element 201 and a switching element 202, and is provided to suppress voltage variation (in other words, capacity variation) in the plurality of single cells 100.

  Here, when the switching element 202 of the discharge circuit 200 is switched from the off state to the on state, part of the current charged in the unit cell 100 also flows into the discharge circuit 200. Thereby, compared with the case where the switching element 202 is an OFF state, the charging current which flows into the cell 100 reduces, and the charge amount of the cell 100 falls. By controlling the amount of charge in this way, voltage variations in the plurality of single cells 100 can be suppressed.

JP 2002-354703 A (paragraph 0013, FIG. 1)

  In a so-called cylindrical unit cell, a positive electrode terminal and a negative electrode terminal are provided at both ends in the longitudinal direction, and when the discharge circuit 200 shown in FIG. Becomes complicated. Specifically, the wiring of the discharge circuit 200 must be arranged along the longitudinal direction of the unit cell. In addition, when a plurality of single cells are arranged side by side in a plurality of directions, the arrangement of wirings for connecting the discharge circuit 200 tends to be complicated.

  Accordingly, an object of the present invention is to provide a power storage device capable of simplifying the wiring of the equalization circuit in a configuration including an equalization circuit for suppressing voltage variation among a plurality of power storage elements. .

  The power storage device according to the present invention includes a power storage module including a plurality of power storage elements, a first resistance element, and a second resistance element. The energy storage device has a positive electrode terminal and a negative electrode terminal at both ends in a predetermined direction, and the plurality of energy storage devices are arranged side by side so that both ends are positioned in substantially the same plane in a state of being connected in series. Has been placed. The first resistance element is connected in parallel to a first element group composed of 2n (n is an integer, hereinafter the same) storage elements connected in series among the plurality of storage elements. The second resistance element is connected in parallel to the second element group composed of 2n storage elements connected in series among the plurality of storage elements, and connected in series in the first element group. One end is connected between the two stored electricity storage elements.

  Here, the first element group includes a storage element in which a positive terminal is connected to one end of the first resistance element and a negative terminal is connected to one end of the second resistance element. Moreover, when the electrical storage elements arrange | positioned adjacently are connected in series via the bus bar, each resistance element can be connected to a bus bar via wiring. And a bus-bar and each resistance element can be attached to the board | substrate. Accordingly, the bus bar and each resistance element can be connected to the plurality of power storage elements using the substrate, and the assemblability of the power storage device can be improved.

  On the other hand, a switching element that is connected in series with each resistance element and switches between energization and non-energization of each resistance element can be provided. In this case, each resistance element and switching element may be connected in parallel to each element group.

  As the power storage element, a so-called cylindrical power storage element having a substantially circular cross-sectional shape orthogonal to the longitudinal direction can be used. In the cylindrical power storage element, a positive electrode terminal and a negative electrode terminal are respectively provided at both ends in the longitudinal direction. When the power storage element having such a configuration is used, the first resistance element and the second resistance element can be disposed on both ends of the power storage element. When a plurality of cylindrical energy storage elements are used, both ends of each energy storage element can be supported by the holder.

  According to the present invention, in a configuration in which a plurality of power storage elements are arranged side by side, the resistance element and the wiring of the resistance element can be positioned on the positive electrode terminal or negative electrode terminal side of the power storage element. Thereby, it is not necessary to arrange the wiring of the resistance element along the power storage element (predetermined direction), and the wiring arrangement can be simplified. In addition, by using the first resistance element and the second resistance element, voltage variation among the plurality of power storage elements can be suppressed.

It is an exploded view which shows the structure of the battery pack which is Example 1 of this invention. FIG. 3 is a schematic diagram illustrating a partial configuration of a battery module in Example 1; 1 is a diagram illustrating a configuration of an equalization circuit in Embodiment 1. FIG. It is a figure which shows the structure of the equalization circuit in the modification of Example 1. FIG. It is a figure which shows the structure of the equalization circuit in Example 2 of this invention. 6 is a schematic diagram illustrating a partial configuration of a battery module in Example 2. FIG. It is a figure which shows the structure of the conventional equalization circuit.

  Examples of the present invention will be described below.

  A configuration of a battery pack (power storage device) that is Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an exploded perspective view showing the configuration of the battery pack.

  The battery pack 1 of the present embodiment can be mounted on a vehicle, and examples of the vehicle include a hybrid vehicle and an electric vehicle. A hybrid vehicle is a vehicle that includes a battery pack 1 in addition to an internal combustion engine or a fuel cell as a power source that outputs energy used to travel the vehicle. An electric vehicle is a vehicle that includes only the battery pack 1 as a power source for the vehicle. The battery pack 1 according to the present embodiment outputs energy used for running the vehicle by discharging, or stores kinetic energy generated during braking of the vehicle as regenerative power. Moreover, the battery pack 1 can also be charged by supplying electric power from the outside of the vehicle.

  The battery pack 1 includes a battery module (storage module) 10 and a pack case 20. The pack case 20 includes a lower case 21 that forms a space for housing the battery module 10, and an upper case 22 that closes the opening 21 a of the lower case 21. The upper case 22 is fixed to the lower case 21 by a fastening member such as a screw or is fixed by welding.

  In the present embodiment, the inside of the pack case 20 is filled with air. However, the present invention is not limited to this, and a gas or liquid other than air can be used instead of air. As the liquid, an insulating liquid such as perfluorocarbon, a fluorine-based inert liquid, or a fatty acid ester can be used. Moreover, when using a liquid, it is preferable to keep the inside of the pack case 20 sealed.

  The battery module 10 includes a plurality of single cells (storage elements) 11 connected in series. The unit cell 11 is a so-called cylindrical battery, and a secondary battery such as a lithium ion battery can be used. Moreover, an electric double layer capacitor (capacitor) can be used instead of the secondary battery. The cylindrical unit cell 11 has a substantially circular cross-sectional shape perpendicular to the longitudinal direction, and the plurality of unit cells 11 are arranged side by side inside the pack case 20. Specifically, when viewed from the longitudinal direction of the unit cells 11, the plurality of unit cells 11 are arranged in a matrix.

  Each unit cell 11 has a power generation element (not shown) and a battery case that houses the power generation element in a sealed state. The power generation element is an element that can be charged and discharged, and can be composed of, for example, a positive electrode element, a negative electrode element, and a separator containing an electrolytic solution. In the present embodiment, a positive electrode element and a negative electrode element are arranged with a separator interposed therebetween, and this laminate is accommodated in a wound state in a cylindrical battery case. The positive electrode element has a positive electrode active material layer formed on the surface of the current collector plate, and the negative electrode element has a negative electrode active material layer formed on the surface of the current collector plate.

  A positive electrode terminal (electrode terminal) 11 a and a negative electrode terminal (electrode terminal) 11 b are provided at both ends in the longitudinal direction of each unit cell 11. The positive electrode terminal 11a is electrically connected to the positive electrode element of the power generation element described above, and the negative electrode terminal 11b is electrically connected to the negative electrode element of the power generation element. The positive electrode terminal 11 a of each unit cell 11 is electrically connected to the negative electrode terminal 11 b of another unit cell 11 disposed adjacent to the unit cell 11 via the bus bar 12. And the several cell 11 which comprises the battery module 10 is electrically connected in series.

  The plurality of bus bars 12 are fixed to the substrate 13 in a positioned state, and are attached to the plurality of single cells 11 positioned by a battery holder 14 described later. The substrate 13 is formed of an insulating material (for example, resin). Each bus bar 12 has a hole (not shown) for penetrating the electrode terminals 11a and 11b, and a nut 16 is attached to the tip of the electrode terminal 11a and 11b that penetrates the hole. With this configuration, the plurality of bus bars 12 can be easily attached to the plurality of single cells 11.

  Each unit cell 11 is supported by a pair of plate-shaped battery holders 14 at both ends. Specifically, each battery holder 14 has a hole (not shown) for penetrating the electrode terminals 11a and 11b of the unit cell 11, and supports the end of the unit cell 11 in the hole. is doing. And in the some cell 11, the both ends of each cell 11 are located in the substantially same surface (in the surface in which the battery holder 14 is located). Here, “substantially the same surface” refers to an assembly tolerance of the plurality of single cells 11.

  The battery holder 14 can be formed of resin, for example, and can be fixed to the pack case 20 (lower case 21) with a fastening member. In addition, although a pair of battery holder 14 is used in a present Example, these battery holders 14 can also be comprised integrally.

  The positive terminal 11a in a specific unit cell 11 of the battery module 10 is a total plus terminal of the battery module 10, and a total plus cable as a high voltage cable is connected to this terminal. Moreover, the negative terminal 11b in the other specific unit cell 11 of the battery module 10 becomes a total minus terminal of the battery module 10, and a total minus cable as a high voltage cable is connected to this terminal. These high-voltage cables can be connected via a system relay to a DC / DC converter that converts voltage values and an inverter that converts between DC power and AC power.

  Next, the configuration of the equalization circuit in this embodiment will be described with reference to FIGS. Here, FIG. 2 is a schematic diagram showing a configuration of a part of the battery module 10, and FIG. 3 is a diagram showing a configuration of an equalization circuit.

  As shown in FIG. 2, a resistance element (so-called balance resistor) 40 is connected to two bus bars 12 arranged adjacent to each other via a wiring 30. A plurality of resistance elements 40 are attached to each substrate 13. The resistance element 40 is used to balance the voltage across the unit cells 11 to which the resistance element 40 is connected, in other words, to suppress variation in capacity among the plurality of unit cells 11.

  FIG. 3 shows a circuit configuration equivalent to the configuration shown in FIG. 2, and each resistance element 40 is connected in parallel to a battery group (element group) composed of two unit cells 11 connected in series. Has been. Specifically, one end of the resistance element 40 is connected to the positive terminal 11 a of one unit cell 11 of the two unit cells 11, and the other end of the resistance element 40 is connected to the negative terminal 11 b of the other unit cell 11. It is connected. In addition, one end of another resistance element 40 is connected between the two unit cells 11 connected in parallel to the resistance element 40. The other resistance elements 40 are also connected in parallel to the two unit cells 11 connected in series.

  In FIG. 3, the resistance element 40 positioned above the plurality of single cells 11 indicates the resistance element 40 that is fixed to one of the pair of substrates 13. Further, the resistance element 40 positioned below the plurality of unit cells 11 indicates the resistance element 40 fixed to the other substrate 13.

  In the configuration described above, when the battery module 10 is charged, a charging current flows to the single battery 11 and also flows to the resistance element 40. Further, when the battery module 10 is discharged, a discharge current flows through the resistance element 40. By using the resistance element 40 in this way, it is possible to suppress voltage variations in the plurality of single cells 11 constituting the battery module 10.

  In the present embodiment, as described above, the plurality of resistance elements 40 can be distributed and arranged on both ends of the unit cell 11, in other words, on the side where the pair of battery holders 14 are located. And the wiring 30 for connecting the resistance element 40 and the bus bar 12 can also be distributed to both end sides of the unit cell 11, and the arrangement of the wiring 30 can be simplified. Thereby, the battery module 10 (battery pack 1) can be reduced in size.

  Here, if the resistance element 40 is to be connected in parallel to one unit cell 11, the wiring connecting the electrode terminals 11 a and 11 b and the resistance element must be arranged along the longitudinal direction of the unit cell 11. Disappear. Further, in order to connect the resistance elements 40 to the plurality of single cells 11 constituting the battery module 10, the arrangement of wirings becomes complicated.

  In the present embodiment, the wiring 30 is only arranged on both ends of the unit cell 11, and it is not necessary to arrange the wiring 30 along the longitudinal direction of the unit cell 11, and the wiring 30 can be easily arranged. In addition, the bus bar 12, the resistance element 40, and the wiring 30 can be attached to each substrate 13 disposed on both ends of the unit cell 11, and the assemblability of the battery module 10 can be improved. That is, by using the substrate 13, the plurality of bus bars 12 and the plurality of resistance elements 40 can be attached to the plurality of single cells 11 at a time, and the battery module 10 can be easily assembled.

  Further, by forming the plurality of resistance elements 40 and the plurality of wirings 30 integrally with the substrate 13 to which the plurality of bus bars 12 are fixed, the resistance elements 40 and the wirings 30 are separated from the substrate 13. Compared with the case where it arranges, it becomes easy to miniaturize the battery module 10.

  In addition, in the equalization circuit in a present Example, although the resistive element 40 is connected in parallel with respect to the two unit cells 11 connected in series, it is not restricted to this structure. Specifically, the equalization circuit can be configured as shown in FIG. FIG. 4 is a schematic diagram showing a configuration of an equalization circuit which is a modification of the present embodiment. In this modification, a switching element is added to the configuration of this embodiment. This will be specifically described below.

  In this modification, a discharge circuit 50 is connected to the plurality of single cells 11, and the discharge circuit 50 includes a resistance element (so-called balance resistance) 51 and a switching element 52. Specifically, each discharge circuit 50 is connected in parallel via the wiring 30 to two unit cells 11 connected in series, and the two unit cells 11 to which the discharge circuit 50 is connected are connected. One end of another discharge circuit 50 is connected between them.

  As in the configuration shown in FIG. 2, the discharge circuit 50 is connected to the two bus bars 12 arranged adjacent to each other in each substrate 13 via the wiring 30. , Fixed to each substrate 13. In FIG. 4, the discharge circuit 50 positioned on the upper side of the plurality of unit cells 11 is fixed to the substrate 13 disposed on one end side of the unit cell 11, and the discharge circuit 50 positioned on the lower side of the plurality of unit cells 11 is The cell 11 is fixed to the substrate 13 disposed on the other end side.

  At the base, the switching element 52 is switched between an on state and an off state by receiving a control signal from a controller (not shown). If the switching element 52 is switched from the off state to the on state, for example, when the unit cell 11 is charged, the charging current flows also to the resistor unit 51, and voltage variation among the plurality of unit cells 11 is suppressed. can do.

  Also in this modified example, since the plurality of discharge circuits 50 can be distributed and arranged on both ends of the unit cell 11, in other words, on each substrate 13, the wiring 30 of the discharge circuit 50 can be simplified. In addition, the discharge circuit 50 and the wiring 30 are integrally attached to the substrate 13 to which the plurality of bus bars 12 are fixed, thereby improving the assembling property of the battery module 10 and reducing the size of the battery module 10. You can plan.

  Next, the configuration of the equalization circuit according to the second embodiment of the present invention will be described with reference to FIGS. Here, FIG. 5 is a diagram showing a configuration of the equalization circuit in the present embodiment, and FIG. 6 is a schematic diagram showing a configuration of a part of the battery module in the present embodiment. In addition, about the member which has the same function as the member demonstrated in Example 1, the same code | symbol is used and detailed description is abbreviate | omitted. Hereinafter, differences from the first embodiment will be mainly described.

  In the first embodiment, the resistance element 40 is connected in parallel to the two unit cells 11 connected in series with each other. However, in the present example, the unit cell includes four unit cells 11 connected in series with each other. A resistance element 40 is connected in parallel to the battery group (element group).

  One of the four resistance elements 40 shown in FIG. 5 is connected in parallel via a wiring 30 to a battery group consisting of four unit cells 11 connected in series. Specifically, one end of the resistance element 40 is connected to the total plus terminal of the battery group, and the other end of the resistance element 40 is connected to the total minus terminal of the battery group.

  Further, in the four unit cells 11 to which the resistance elements 40 are connected in parallel, one end of each of the other three resistance elements 40 is connected between the two unit cells 11 connected in series. If comprised in this way, as shown in FIG. 6, the four resistive elements 40 can be distributed and arrange | positioned at the both ends of the cell 11. As shown in FIG. In FIG. 6, each resistance element 40 is connected to two bus bars 12 via wiring 30. Also in this embodiment, the resistance element 40 and the wiring 30 are attached to the substrate 13 to which the plurality of bus bars 12 are fixed.

  Also in the present embodiment, similarly to the first embodiment, by using the plurality of resistance elements 40, it is possible to suppress voltage variation in the plurality of single cells 11. Moreover, since the resistive element 40 and the wiring 30 can be distributed and arranged on both ends of the unit cell 11, the wiring 30 can be simplified. Furthermore, the assembly of the battery module 10 can be improved or the battery module 10 can be downsized by integrally attaching the resistance element 40 and the wiring 30 to the substrate 13.

  In the present embodiment, only the resistance element 40 is used. However, similarly to the case described in the modification of the first embodiment, the discharge circuit 50 including the resistance element 51 and the switching element 52 can also be used. In this case, the discharge circuit 50 may be connected in parallel via the wiring 30 to the four unit cells 11 connected in series.

  In the present embodiment, the resistance elements 40 are connected in parallel to the four unit cells 11, but the present invention is not limited to this. Specifically, the resistance element 40 can be connected in parallel to 2n (n is an integer) unit cells 11 connected in series. In the 2n unit cells 11 to which the resistor element 40 is connected, one end of another resistor element 40 can be connected between the two unit cells 11 connected in series.

  If comprised in this way, the some resistive element 40 and the wiring 30 can be distributed and arrange | positioned at the both ends of the cell 11, and the wiring 30 can be simplified. Further, similarly to the first embodiment, the resistor element 40 and the wiring 30 can be integrally attached to the substrate 13, so that the assembling property of the battery module 10 can be improved or the battery module 10 can be downsized. .

  On the other hand, although the present Example demonstrated the case where the cylindrical cell 11 was used, it does not restrict to this. That is, the present invention can be applied as long as the positive electrode terminal 11a and the negative electrode terminal 11b of the unit cell 11 protrude in different directions from the battery case. And even if it is a case where what is called a square cell 11 is used, if the positive electrode terminal 11a and the negative electrode terminal 11b are in the positional relationship mentioned above, this invention is applicable.

1: Battery pack (power storage device) 10: Battery module (power storage module)
11: Cell (electric storage element) 11a: Positive terminal 11b: Negative terminal 12: Bus bar 13: Substrate 14: Battery holder 20: Pack case 21: Lower case 21a: Opening 22: Upper case 30: Wiring 40: Resistive element 50 : Discharge circuit 51: Resistance element 52: Switching element

Claims (8)

A plurality of power storage elements each having a positive electrode terminal and a negative electrode terminal at both ends in a predetermined direction, in a state where the power storage modules are connected in series, the power storage modules arranged side by side so that the both end portions are positioned in substantially the same plane;
A first resistance element connected in parallel to a first element group consisting of 2n (n is an integer, hereinafter the same) of the plurality of power storage elements connected in series;
Among the plurality of power storage elements, two power storages connected in series to a second element group including 2n power storage elements connected in series and connected in series included in the first element group A second resistance element having one end connected between the elements;
A power storage device comprising:   2. The first element group includes the power storage element in which the positive terminal is connected to one end of the first resistance element and the negative terminal is connected to one end of the second resistance element. The power storage device described in 1. It has a bus bar for connecting the power storage elements arranged next to each other in series,
The power storage device according to claim 1, wherein each of the resistance elements is connected to the bus bar through a wiring.   The power storage device according to claim 3, further comprising a substrate for supporting the bus bar and each of the resistance elements. Each of the resistance elements is connected in series, and has a switching element for switching between energization and non-energization of the resistance elements,
2. The power storage device according to claim 1, wherein the resistance elements and the switching elements are connected in parallel to the element groups.   2. The storage element according to claim 1, wherein the cross-sectional shape perpendicular to the longitudinal direction is formed in a substantially circular shape, and the positive electrode terminal and the negative electrode terminal are provided at both ends in the longitudinal direction. The power storage device according to any one of 5.   The power storage device according to claim 6, wherein the first resistance element and the second resistance element are respectively disposed on both ends of the power storage element. The power storage device according to claim 6, further comprising a holder for supporting both ends of the power storage element.

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