JP6341828B2 - Power storage device combined with power storage module - Google Patents

Description

  The present invention relates to a power storage device that is combined with a power storage module to increase voltage and capacity, and is particularly suitable for a secondary battery system for railway vehicles.

A secondary battery system including a plurality of high-power density storage cells such as lithium ion batteries is widely used for industrial applications. Particularly in recent years, secondary battery systems with high voltage and large capacity have begun to spread as power storage systems for vehicles.
In the field of railcars, this secondary battery system is also combined with a generator driven by a diesel engine and a secondary battery system in a hybrid railway vehicle that supplies power to the motor or an electric vehicle for regeneration. A train system that absorbs the regenerative power to the secondary battery when there is no load. Furthermore, for the purpose of eliminating overhead lines, the train runs between the stations using the secondary battery system as the power source, and the station charges the secondary battery system. It is widely used to save energy as an application of a hybrid train using a train line and a secondary battery system.

  A secondary battery system for a railway vehicle usually requires a voltage of 750 to 1500 V and a large capacity of several tens to several hundreds kWh. On the other hand, considering the ease of maintenance and inspection of the storage cell, safety, transportability, etc., it is desirable that the storage cell is modularized in units of several to several tens. Furthermore, from the viewpoint of safety, there is a strong demand for downsizing and cost reduction in consideration of the constraints of the equipment space and the like in securing both cooling performance and insulation.

As a background art of this technical field, Patent Document 1 discloses a configuration example of a power storage device box having high cooling performance and high insulation performance as a configuration example of a power storage device box mounted on a railway vehicle.
As a configuration example described in Patent Document 1, FIG. 8 shows a cross-sectional structure of a power storage device box.
In FIG. 8, 20 is a power storage device box, 21 is a power storage cell, 22 is a cooling fan, 23a and 23b are insulating materials, 24 is a heat sink, and 25a and 25b are side plates. In the example of FIG. 8, the energy storage module is mounted in four stages in the vertical direction. The side plates 25a and 25b are wind walls of cooling air, and the cooling air passes through the heat sink 24 as shown in FIG. Further, insulating materials 23a and 23b are provided between the power storage modules and between the power storage device box and the power storage module. With this configuration, a power storage device having high cooling performance while ensuring insulation performance is realized.

On the other hand, in order to ensure the cooling performance, it is necessary to consider the temperature uniformity of the storage cell. For example, when a variation occurs in the temperature of the storage cells in the storage module or between the storage modules, the storage cell that has reached a high temperature deteriorates and the capacity decreases. The capacity that can be charged or discharged is reduced due to the capacity reduction of the storage cell.
For this reason, when a storage cell or a storage module that has been deteriorated due to temperature variations and has been deteriorated is connected in series and a charge / discharge current flows, only the deteriorated storage cell is overcharged or overdischarged. When the overcharge or overdischarge state is repeated, the storage cell or the storage module further deteriorates. As the deterioration progresses, if the function of the storage cell does not meet the standard or if a short-circuit failure occurs and it is incorporated in a railway vehicle system, it will result in a system failure, resulting in an overall system lifespan. It will shrink.

  In order to prevent such a situation, it is desirable to perform cooling while achieving uniform temperature between the storage cells or between the storage modules. As a configuration for reducing the temperature difference between the power storage modules, Patent Document 2 discloses a configuration for reducing the temperature difference between power storage cells stacked in the vertical direction by turning on and off the cooling fan. In other words, if the temperature difference is below a certain value, the cooling fan is stopped and operates so that the temperature above the lower side increases, and if the temperature difference exceeds a certain value, the cooling fan is operated and the upper cell is operated. By operating to lower the temperature, the temperature of the storage cell is made uniform.

JP 2011-187275 A JP 2007-095482 A

However, the systems shown in these patent documents have the following problems.
In the configuration example described in Patent Document 1, since the storage cell is indirectly cooled by the heat sink, it is a problem to further improve the cooling efficiency. In addition, there is a problem that a heat sink is necessary, and an insulating material is mounted for each power storage module, and the device is enlarged even if cooling performance and insulation performance are secured. Further, when the power storage modules are stacked in multiple stages, the size in the vertical direction becomes large, and it is impossible to equip the railcar under the floor. Further, when the module is housed in the power storage device box and cooling is performed in units, the temperature on the upper side of the power storage module increases, and the temperature variation and current variation between the power storage modules increase.

  In the configuration example described in Patent Document 2, the temperature difference between the storage cells can be eliminated. However, in railway vehicles and the like, the charge / discharge current is large, and the temperature of the storage cell is always high in normal use. In a state in which the overall temperature has increased due to continuous use or the like, the fan needs to operate continuously, so that it cannot be used as shown in Patent Document 2, and continuous cooling by the fan and the temperature of the storage cell The difference cannot be suppressed.

  Therefore, an object of the present invention is to achieve both the high cooling performance with the temperature difference of the storage cells made uniform, the insulation performance, and the miniaturization for securing the equipment space.

In order to solve the above three problems at the same time, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-mentioned problems. To give an example, in the power storage device of the present invention, a plurality of power storage cells are connected in series, parallel, or a combination of series connection and parallel connection. A power storage module having a predetermined potential, an insulating material, and a cooling unit, wherein the power storage module is an array of the power storage cells in a case having a cooling air passage along the periphery of the body portion of the power storage cell. A plurality of the power storage modules are connected in series and arranged so that the cooling air from the cooling unit is directly introduced into the cooling air inlets provided in each of the cases, and the power storage module and the power storage with an insulating material between power storage device box for housing the modules and the cooling unit, and the storage module, between said cooling unit It was integral unit via an insulating material.

In this way, by insulating the power storage module in units of one unit and providing a cooling unit, it is possible to achieve downsizing, and in particular, the size in the vertical direction can be reduced. It is valid.
In addition, while ensuring high cooling performance, the temperature difference between power storage cells or power storage modules can be reduced, and furthermore, insulation performance can be secured with the minimum required insulating material. Miniaturization can be realized at the same time.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

FIG. 1 is a diagram illustrating a structure example of a power storage device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a cross-sectional structure of the power storage device according to the first embodiment. FIG. 3 is a diagram illustrating a circuit connection example of the power storage module according to the first embodiment. FIG. 4 is a diagram illustrating a structural example of an integrated unit of the power storage module according to the first embodiment. FIG. 5 is a diagram illustrating an internal structure example of the power storage module according to the first embodiment. FIG. 6 is a diagram illustrating a structure example of the power storage device according to the second embodiment. FIG. 7 is a diagram illustrating a structure example of the power storage device according to the third embodiment. FIG. 8 is a diagram illustrating a structure example of a conventional power storage device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Example 1]
FIG. 1 is a diagram illustrating a structure example of a power storage device according to the first embodiment of the present invention.
In FIG. 1, as will be described later, 1 is a power storage module configured by combining a plurality of power storage cells and arranging them in a case, 7 is a cooling fan unit, and 14 a is a cooling fan installed in the cooling fan unit 7. , 6 is a power storage device box that houses the power storage module 1 and the cooling fan unit 7, 2 is an insulating material between the power storage module 1 and the cooling fan unit 7, 3a and 3b are insulating materials between the power storage module 1 and the power storage device box 6, 9 is a frame for connecting the power storage device box and the power storage module, and 15 is a frame for connecting a cooling fan.
Reference numeral 16 denotes an integrated unit in which the power storage module 1, the cooling fan unit 7, the insulating material 2, and the insulating materials 3a and 3b are integrated and fixed.

FIG. 2 is a cross-sectional view of the power storage device as viewed from the direction A in FIG. 1, and a dotted arrow indicates an example of the flow of cooling air by the cooling fan. 8 is an example of a frame for mounting the integrated unit 16, and the structure for connecting and fixing the power storage device box 6 is not limited to this.
In addition, although the example of the cooling fan unit which mounted the fan is shown as a cooling unit in FIG. 1, the unit which takes in the cooling air from the outside by a duct etc. may be sufficient.

In the following, the features that are characteristic of the first embodiment will be described in order from the three viewpoints of mounting, insulation, and cooling, taking as an example a power storage module that is connected in a circuit in the vertical direction.
First, the mounting corresponding to the circuit connection of the storage module in the vertical direction will be described. FIG. 3 shows a connection example of the power storage circuit.

  In FIG. 3, reference numeral 10 denotes a storage cell, and reference numerals 1 a to 1 r surrounded by a dotted line frame denote a storage module in which a plurality of storage cells 10 are connected and combined into one case. The thing corresponding to the electrical storage modules 1a-1d in FIG. 1 respond | corresponds to the electrical storage modules 1a-1d shown in FIG.

  In FIG. 1, the storage modules in the storage device box 6 are mounted in the vertical direction by connecting the storage modules in series as in 1a to 1d and mounting them in the vertical direction. Although FIG. 1 shows an example in which the power storage modules 1a to 1d are mounted, the power storage modules 1e to 1h, 1i to 1m, and 1n to 1r shown in FIG. 3 are similarly mounted in the vertical direction. 1 and 3 show an example of four series and four parallels, but the number of series and parallel columns is not limited to this, and two or more series of power storage modules are arranged in the vertical direction by the number of power storage modules in series. It is configured to be loaded and provided in the same form for the number of parallel connections.

For example, in FIG. 4, if the power storage modules 1a, 1e, 1i, and 1n are connected in parallel in the vertical direction, and these power storage modules are combined and mounted in the vertical direction, the current flowing between the parallel connections is unbalanced. become.
This is because the power storage module mounted in the vertical direction is cooled by the cooling air and operates so that there is no temperature variation between the power storage modules, but in the power storage device box 6, warm air is on the upper side, and Cold air is distributed on the lower side. As a result, the temperature of the upper power storage module 1a is higher than that of the lower power storage module 1n. Since the internal resistance of a power storage cell such as a lithium ion battery decreases as the temperature rises, the resistance of the power storage module 1a on the upper stage is smaller than that on the lower stage, and the power storage module 1a has more current than the power storage module 1n. Will flow.

  The difference between the current values of the power storage modules 1a and 1n means that a current imbalance has occurred between the power storage modules 1a and 1n shown in FIG. 3 and that there is an unbalance between the parallel connections. As the temperature rises and the resistance decreases, the electricity storage module 1a becomes larger in current, which is further promoted to increase in temperature and easily deteriorate.

On the other hand, in the present embodiment, as shown above, by connecting the power storage modules in series and mounting them in the vertical direction, the current flowing through each power storage module becomes uniform, and this problem can be prevented. it can.
However, if the storage modules are connected in series, the total output voltage is the product of the output voltage of each storage module and the number of storage modules.Therefore, when connecting multiple storage cells in each storage module, the series and parallel are connected. In combination, the output voltage of each power storage module is adjusted to a predetermined potential.

Next, insulation will be described. In the conventional configuration shown in FIG. 8, as described above, the insulating materials 23a and 23b are inserted between the modules or between the power storage device box 20 and the power storage module. This is because electrical insulation is provided for the power storage device box 20 or the heat sink 24 having the same potential as the power storage device box 20.
On the other hand, in FIG. 1, since the cooling performance is ensured by the cooling method described later, the heat sink is not mounted and the insulation with the heat sink is unnecessary. Further, by setting the frame potential of the power storage modules to the same potential in units of combination of power storage modules connected in series, insulation in units of power storage modules becomes unnecessary. For this reason, what is necessary is just to insulate in the unit of combination of the storage module connected in series, and the quantity of an insulating material can be reduced and it can make compact.

Specifically, in FIG. 1, the power storage modules 1 a to 1 d are fixed as a combination unit on the frame 9, and the insulating material 3 a is inserted between the frame 8 for supporting the combination unit on the power storage device box 6. Thus, electrical insulation is ensured. In addition, since the cooling fan unit 7 is connected to the low voltage circuit, insulation is ensured by the insulating material 2. In addition, in order to insulate the combination unit of the power storage modules and the cooling fan unit, an insulating material is inserted in FIG. 1, but a system in which an insulation distance is secured may be used.
However, if there is a gap between the cooling fan unit 7 and the power storage module as in the conventional example, the cooling efficiency is deteriorated. Therefore, as shown in FIG. It is desirable that the cooling air be blown to the power storage cell in the power storage module without leaking to the outside as much as possible. In addition, the power storage module 1 a, the frame 9, the insulating materials 2, 3 a, 3 b and the cooling fan unit 7 are integrated to form an integrated unit 16.

Finally, cooling will be described. FIG. 5 is a diagram showing the internal structure of the power storage module 1.
In FIG. 5, 10 is a power storage cell, 11 is an electrode connection line, 12a and 12b are wind walls provided in the case of the power storage module 1, and 13a and 13b are cooling air paths. FIG. 5A shows the configuration of the power storage module showing the direction A in FIG.

  The cooling fan 14a of the cooling fan unit 7 is provided for each power storage module unit, and cools the power storage cell 10 by flowing cooling air along the dotted line arrow in FIG. By providing a cooling fan for each power storage module unit, the fan can be turned on / off or the air volume can be adjusted for each power storage module unit, and a temperature difference between the power storage modules can be reduced. In addition, since there are a plurality of cooling fans, even if one or several cooling fans fail, it can be cooled by other cooling fans, so that redundancy can be improved.

5B is a diagram viewed from the A direction in FIG. 5A, and FIG. 5C is a diagram viewed from the B direction in FIG. 5B.
The wind wall 12a is provided inside the power storage module 1 along the electrode connection portion of the row of the power storage cells 10 arranged linearly. The wind wall 12b is provided between the rows of the plurality of power storage cells, and the wind walls 12a and 12b are exited from the cooling wind inlet end in the longitudinal direction of the power storage module 1 (left-right direction in FIG. 5A). Shut off the cooling air until it reaches the edge.

By these wind walls 12 a and 12 b, the cooling air is concentrated on the cooling air passages 13 a and 13 b, and the cooling air is intensively blown directly to the body portion of the storage cell 10.
Since the power storage cell generates the most heat in the body of the cell, by concentrating the cooling air on the body of the cell, the temperature difference from the outside air temperature to be taken in becomes large, and the cooling efficiency can be improved. Furthermore, according to this structure, wind does not hit the electrode surface 11 due to the wind wall 12a, so that the electrode portion can be prevented from being stained, and there is also an effect of preventing insulation deterioration and conductivity deterioration due to electrode contamination.
1 and 5, the direction of the cooling air is taken in by the cooling fan. However, the cooling air may be exhausted from the cooling fan and sent to the power storage module. Further, the temperature of the cooling fan may be increased on the upper side where the temperature becomes higher so as to achieve further uniform temperature.

  By configuring the power storage device by combining the power storage modules characterized in terms of mounting, insulation, and cooling as described above, it is possible to reduce the temperature difference between the power storage cells or the power storage modules while ensuring high cooling performance, Further, the insulation performance can be ensured with the minimum necessary, and the necessary cooling performance, insulation performance and downsizing can be realized at the same time.

[Example 2]
FIG. 6 is a diagram illustrating a configuration example of a power storage device according to the second embodiment of the present invention. The difference from the first embodiment is that the cooling fan unit 7 has a single cooling fan (only the cooling fan 14a). Thereby, the number of fans can be reduced, and the number of wirings to the fans can be reduced, which is economical. At that time, a distribution duct is provided between the fan and each power storage module so that the cooling air introduced or sucked from the fan is evenly distributed to each power storage module, or the area of the cooling air intake of the power storage module is lowered. The temperature can be made more uniform by sequentially increasing from the top to the top.

[Example 3]
FIG. 7 is a diagram illustrating a configuration example of the power storage device according to the third embodiment of the present invention. The difference from the configuration of the first embodiment is that the power storage module has the insulating material 3c on the left and right in the horizontal direction. Thereby, the space between the integrated units 16 can be reduced, and a further miniaturized power storage device box can be realized.

In addition, this invention is not limited to an above-described Example, Various modifications are included.
For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1, 111 ... power storage module, 2 ... insulating material between cooling fans,
3a, 3b, 3c ... insulating material between power storage device boxes, 5, 2 ... cooling fan,
6 ... power storage device box, 7 ... cooling fan unit,
8: Frame for mounting the storage module,
9: Frame for connecting the power storage device box and the power storage module;
10 ... electric storage cell, 11 ... electrode connection line, 12a, 12b ... wind wall,
13a, 13b ... cooling air passages, 14a, 14b ... cooling fans,
15 ... Frame for mounting cooling fan, 16 ... Integral unit

Claims (6)

A series connection of a plurality of storage cells, a parallel connection, or a combination of series connection and parallel connection, a storage module having a predetermined potential, an insulating material, and a cooling unit,
The power storage module is a structure in which the power storage cells are arranged in a case having a cooling air passage along the periphery of the body portion of the power storage cell,
A plurality of the power storage modules are combined and connected in series, and arranged so that the cooling air from the cooling unit is directly introduced into the cooling air intakes provided in each of the cases, the power storage module, the power storage module, An electrical storage device , wherein an insulating material is provided between the electrical storage device box that houses the cooling unit, and an integrated unit is provided between each electrical storage module and the cooling unit via an insulating material. The power storage device according to claim 1,
A power storage device, wherein the integrated unit is stacked in a vertical direction, a horizontal direction, or a combination of a vertical direction and a horizontal direction. The power storage device according to claim 1 or 2,
The power storage device, wherein the cooling unit is a cooling fan unit provided for each power storage module. The power storage device according to claim 3,
The power storage device according to claim 1, wherein the cooling fan unit is configured such that, in the power storage module, an upper fan air volume is set larger than a lower fan air volume. In the electrical storage apparatus of any one of Claims 1-4,
A power storage device, wherein a wind wall is provided inside the power storage module corresponding to the electrode connection portion position in a row of power storage cells arranged linearly along the cooling air from the cooling unit. The power storage device according to claim 4,
The storage cells are provided in a plurality of rows, and between each row, along the cooling air from the cooling unit,
A power storage device provided with a wind wall.

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