JP4042260B2 - Battery pack and charging method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an assembled battery comprising a plurality of unit cells.
[0002]
[Prior art]
In a high-voltage, large-capacity assembled battery, for example, a power battery for an electric vehicle, as shown in FIG. 3, a large number of single cells 1 are connected in series to increase the voltage, and the series circuit 2 is configured in a plurality of rows. The capacity is increased by parallel connection, and this is connected to the load 3.
On the other hand, when charging the assembled battery, as shown in the figure, it is common to connect to the charging device 4 while maintaining the above-described series-parallel connection state.
[0003]
[Problems to be solved by the invention]
However, in the above charging method, if any single cell 1 causes an internal short circuit during charging, even if the operation of the charging device 4 is interrupted, a short circuit current flows from the other series circuit 2. With conventional low-voltage and small-capacity assembled batteries with a small number of series connections and parallel circuits, the value of short-circuit current does not increase so much, and accident currents tend to gradually fall, but with high-voltage and large-capacity assembled batteries, The effect turned out to be enormous.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an assembled battery that can prevent a serious accident from occurring even if a short-circuit accident of a single battery occurs during charging. It is in providing the charging method.
[0005]
[Means for Solving the Problem and Action]
The invention of claim 1 is a battery pack in which a series circuit in which a plurality of single cells are connected in series is connected in parallel and connected to a load . It is characterized in that the charging device is connected to each of the series circuits connected in series .
In this configuration, since the series circuit in which the single cells are connected in series is not connected in parallel at the time of charging, even if an internal short circuit of the single cell occurs at the time of charging, no accident current flows from other series circuits, It is possible to prevent an accident such as abnormal heat generation or ignition of a short-circuited unit cell.
[0006]
The invention of claim 2 is characterized in that a charging device is connected to each series circuit. There is an advantage that the capacity of the charging device can be reduced.
The assembled battery according to the invention of claim 3 is composed of a plurality of single cells, wherein a series circuit in which the single cells are connected in series is connected in parallel and connected to a load, and the series circuits are separated from each other. It has a feature in that it includes a switch that switches from the parallel connection state to a state in which each series circuit is connected to the respective charging device, and has the same operations and effects as the invention of claim 1.
[0007]
Further, in the assembled battery according to the invention of claim 4, the switch is configured such that only a part of the plurality of series circuits is connected in parallel and connected to the load, and the other series circuits are disconnected from the load. Has characteristics. If it does in this way, while being able to suppress unnecessary heat_generation | fever of the cell group disconnected from load, it is desirable from the surface of ensuring safety | security, and when using a lithium ion secondary battery as a cell especially, it is suitable.
[0008]
【The invention's effect】
As described above, according to the present invention, a large accident is caused even if an internal short circuit occurs during charging in a case where a large number of single cells are connected in series and parallel to increase the voltage and capacity. This can be prevented beforehand.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The cell 10 is, for example, a lithium ion type secondary battery, and for example, 120 of these are connected in series to form a series circuit 11. For example, seven series circuits 11 are provided, and a high-voltage, large-capacity assembled battery is configured in which the total number of single cells 10 is 120 × 7 = 840.
[0010]
Terminals 12 and 13 are provided on both the positive side and the negative side of each series circuit 11, and a single-pole single-throw switch 14 is provided between adjacent series circuits 11. Therefore, when all the switches 14 are closed, all the series circuits 11 are connected in parallel, and when all the switches 14 are opened, each series circuit 11 is released from the parallel connection and becomes independent.
[0011]
In the above configuration, when the assembled battery is connected to the load 20, as shown in FIG. 1, the switch 14 group is closed so that the entire series circuit 11 is in a parallel connection state, 20 is connected. At this time, the discharge state can be managed by measuring the voltage for each cell 10, the overall output voltage, the load current of each series circuit 11, the overall load current, and the like.
[0012]
On the other hand, when the assembled battery is charged, as shown in FIG. 2, all the switch 14 groups are opened and the series circuits 11 are released from the parallel connection state, so that the seven series circuits 11 are made independent. Thereby, 120 unit cells 10 constitute a single series circuit 11. Therefore, charging is performed by connecting the charging device 30 to the terminals 12 and 13 of each series circuit 11. In this case, for example, the charging operation can be managed by detecting the voltage of each cell 10 and the voltage / current of each series circuit 11.
[0013]
If an internal short circuit accident occurs in any of the unit cells 10 during this charging operation, the current suddenly increases in the series circuit 11 to which the unit cell 10 belongs. The operation of the connected charging device 30 is stopped.
At this time, since there is no circuit connected in parallel to the unit cell 10 causing the internal short circuit, if the charging device 30 is cut off, the accident current immediately converges and the unit cell 10 may be abnormally heated or ignited. There is no.
[0014]
As described above, according to the present embodiment, a large number of single cells 10 are connected in series and parallel to increase the voltage and capacity, but even if an internal short circuit of the single cells 10 occurs during charging, The effect of preventing an accident from occurring can be obtained.
[0015]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention. Various modifications can be made without departing from the scope.
(1) The present invention is particularly effective when the unit cell is a lithium ion secondary battery. However, the present invention is not limited to this, and can be applied to other types of batteries such as a nickel hydrogen type.
(2) In the above embodiment, 840 unit cells 10 are connected in series and parallel, but the number of cells used is not limited to this. Further, although during charging was to use a charging device 30 of a total of seven to connect the charging device 30 to the respective series circuits 11 is not limited to this, a plurality of series circuits 11 of the part For instance series And it is good also as a structure which connects a charging device to each.
(3) In the above embodiment, all the series circuits 11 are connected in parallel and connected to the load 20 at the time of discharging. However, when the load capacity is small, only one or a plurality of some series circuits 11 are connected. It is good also as a switch structure which connects in parallel and connects to the load 20, and disconnects the other series circuit 11 from the load 20 (invention of Claim 4). If it does in this way, while being able to suppress unnecessary heat_generation | fever of the cell group 10 separated from the load 20, it is desirable from the surface of ensuring safety | security, and when using a lithium ion secondary battery as a cell especially, it is suitable.
[Brief description of the drawings]
FIG. 1 is a circuit diagram during discharging of an assembled battery according to an embodiment of the present invention. FIG. 2 is a circuit diagram during charging. FIG. 3 is a circuit diagram showing a state of charging and discharging of a conventional assembled battery. ]
10 ... cell 11 ... series circuit 14 ... switch 20 ... load 30 ... charging device

Claims (4)

In an assembled battery in which a series circuit in which a plurality of single cells are connected in series is connected in parallel and connected to a load,
A method for charging an assembled battery, wherein the series circuit is unwound from a state of being connected in parallel at the time of charging, and a plurality of series circuits are connected in series and a charging device is connected to each of them. In an assembled battery in which a series circuit in which a plurality of single cells are connected in series is connected in parallel and connected to a load,
  A method for charging an assembled battery, wherein the series circuit is solved from a state of being connected in parallel at the time of charging, and a charging device is connected to each series circuit.   In the case of a plurality of unit cells, a state in which a series circuit in which the unit cells are connected in series is connected in parallel and connected to a load, and each series circuit is uncoupled from each other by disconnecting the series circuits from each other. An assembled battery comprising a switch for switching to a state of being connected to each charging device.   4. The assembled battery according to claim 3, wherein the switch has a configuration in which only a part of the series circuit is connected in parallel and connected to a load, and the other series circuit is disconnected from the load.

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