JP4560825B2 - Assembled battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an assembled battery formed by connecting a plurality of batteries, and more particularly to an assembled battery configured by appropriately connecting single cells such as a lithium ion secondary battery. Is suitably used as a power source for electric vehicles and hybrid vehicles.
[0002]
[Prior art]
In recent years, the need for electric vehicles and hybrid vehicles has increased from the viewpoint of energy saving and air pollution problems, and the importance of batteries for electric vehicle power supplies has also increased. One of the important technologies for such electric vehicle power supply batteries is ensuring reliability. When an abnormality occurs in a battery, the abnormal battery is made independent from the system to reduce the impact on other batteries. However, there is a need for technology that does not interfere with the subsequent driving of the car.
As such a technique, conventionally, a unit battery or an assembled battery configured by connecting a group of cells connected in series to each other in parallel has been proposed in which a fuse is connected in series to a unit cell or a series battery group. (Japanese Patent Laid-Open No. 5-250799).
[0003]
[Problems to be solved by the invention]
However, simply connecting a fuse in series to the battery as in the conventional technique has a problem that sufficient reliability as a battery for an electric vehicle power source cannot be ensured for the following reason.
In other words, for batteries where a constant load current always flows, the fuse blown current value can be set close to the load current value, and the fuse can be blown with a small excessive current. There is a large difference between the load current during normal driving and the maximum load current (although there is not much flow of the maximum load current), and the load fluctuation is large, so the fuse used for this must have a large capacity In such a large-capacity fuse, for example, there is a possibility that a small leakage current when a micro short circuit occurs in the battery cannot be detected.
[0004]
In addition, when an abnormal battery occurs, it is necessary to leave a power source for the vehicle to move to a safe place. In consideration of this, all batteries, especially in an electric vehicle and a series hybrid vehicle, should be kept. There is also a problem that it is difficult to separate the load from the load at once.
[0005]
The present invention has been made paying attention to such problems of the prior art, and the object of the present invention is to reliably detect abnormalities such as micro short-circuits occurring in the battery and disconnect the abnormal battery from the system. Another object of the present invention is to provide an assembled battery that can secure the minimum necessary power without causing the adverse effect of the abnormal battery to affect other parallel batteries.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have made it possible to detect battery abnormality even in a battery parallel circuit, and when abnormality occurs in the battery, the abnormality is detected with a voltmeter, In response to the signal, a large current is passed through a current bypass circuit connected in parallel to the battery, and the circuit is surely interrupted. The present invention has been found to solve the above problems, and the present invention has been completed.
[0007]
That is, the assembled battery of the present invention is an assembled battery in which batteries are connected in parallel.
Means for detecting abnormality of the battery, means for controlling energization, a current bypass circuit having a resistor connected in parallel to each of the batteries, and an overcurrent connected in series to the bypass circuit and the battery Means for electrically interrupting the circuit.
[0008]
In a preferred embodiment of the assembled battery of the present invention, the battery is a battery group in which a plurality of single cells are connected in series.
[0009]
Furthermore, in another preferred embodiment of the assembled battery of the present invention, the means for detecting abnormality of the battery detects a voltage of a part or all of the series battery group with a voltmeter, and the voltage exceeds a predetermined value. In this case, the voltmeter is installed for each battery, and when any of the batteries shows a voltage higher than a predetermined value, the voltage is parallel to the battery. It is desirable that the voltmeter connected to be detected and send a signal to the switch of the bypass circuit to close the bypass circuit.
[0010]
Furthermore, in another preferred embodiment of the assembled battery of the present invention, the average voltage of the unit cell is V (V), the internal resistance is rc (Ω), the number of series connections of the series battery group is m (pieces), When the number of parallel connections of the assembled battery is n (pieces), and the normal maximum load current is (Imax),
The capacity of the fuse is 2Imax, and the resistance value of the bypass circuit is (mV / 2Imax) − (rcm / n) (Ω) or less .
[0011]
[Action]
In the assembled battery of the present invention, a means for detecting abnormality of a battery connected in parallel or a series battery group in which a plurality of single cells are arranged in series, a means for controlling energization, and a current bypass circuit having a resistor are combined. Therefore, it is possible to reliably detect abnormalities such as micro short-circuits that could not be detected by the fuse, etc., and disconnect the abnormal battery from the circuit at an early stage. The minimum power required for the assembled battery can be ensured without overdischarge or the like reaching other batteries.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the assembled battery of the present invention will be described in detail.
The assembled battery of the present invention is formed by connecting batteries in parallel, and is connected in parallel to means for detecting an abnormality of a part or all of the battery (hereinafter abbreviated as “abnormality detection means”) and each of the batteries. In addition, a means for controlling energization (hereinafter abbreviated as “energization control means”), a current bypass circuit having a resistor, and the bypass circuit and the battery connected in series, the circuit is electrically interrupted by an overcurrent. Means (hereinafter abbreviated as “circuit interruption means”). Moreover, as the battery, a battery group in which a plurality of single cells are connected in series can be applied.
[0013]
Here, as the abnormality detecting means, it is appropriate to detect an abnormality when a predetermined value is exceeded with a voltmeter, for example, because of its high accuracy. Further, as the energization control means, for example, a switch is appropriate from the viewpoint of convenience and reliability. Further, as the circuit breaking means, for example, a fuse is appropriate from the viewpoint of reliability.
[0014]
The average voltage of the unit cells is V (V), the internal resistance of the unit cells is rc (Ω), the number of series connections of the series battery group is m (pieces), and the number of parallel connections of the assembled batteries is n ( When the maximum normal load current is (Imax), the capacity of the fuse is appropriate to be twice the maximum load current during normal use in consideration of the safety factor. The resistance value of the bypass circuit is , (MV / 2Imax) − (rcm / n) (Ω) or less .
[0015]
Furthermore, examples of the unit cell include a sodium sulfur battery, a nickel cadmium battery, a nickel metal hydride battery, a lithium battery, and a lithium ion battery. In particular, it is preferable to use a lithium ion secondary battery in which lithium manganate is used for the positive electrode and carbon is used for the negative electrode from the viewpoints of suitability for a parallel assembled battery and suitability as a battery for an electric vehicle power source. In addition, since the lithium ion battery does not cause a problem even if an external short circuit occurs, the minimum value of the resistance of the bypass circuit can be set to 0Ω.
[0016]
Next, the assembled battery of the present invention described above will be described based on a preferred embodiment.
[0017]
(Embodiment 1)
As shown in FIG. 1, in this assembled battery 8, a voltmeter 2, which is an example of an abnormality detection means, is connected to each unit cell 1, and a series battery group 7 formed by the unit cells 1 has an energization control unit. An example switch 4 and a current bypass circuit 3 having a resistor 5 are connected in parallel, and the current bypass circuit 3 and the series battery group 7 are connected in series with a fuse 6 as an example of the circuit interrupting means. . The switch 4 can be controlled to open and close by a switch controller 9 connected to each voltmeter 2.
As the unit cell 1, a lithium ion secondary battery using lithium manganate as a positive electrode and carbon as a negative electrode is used, and the assembled battery 8 is installed in a hybrid vehicle.
[0018]
Moreover, this assembled battery 8 detects the abnormal voltage of any single cell with the voltmeter 2, and allows a current to flow through the bypass circuit 3 connected to the series battery group 7 in which an abnormality has occurred by the switch 4. it can. When a current is passed through the bypass circuit 3, an overcurrent is caused to flow through the fuse 6 due to the overcurrent, so that the circuit including the abnormal battery can be made independent from the system.
[0019]
Furthermore, this assembled battery 8 has an average voltage V (V) of the unit cells, an internal resistance of the unit cells rc (Ω), a number of series connections of the series battery group m (pieces), and a number of parallel connections of the assembled cells. Is n (pieces) and the normal maximum load current is (Imax), the fuse capacity is 2Imax, and the resistance value of the bypass circuit is (mV / 2Imax) − (rcm / n) (Ω) or less. It becomes.
[0020]
In the assembled battery 8 described above, when an abnormality such as an internal short circuit occurs, it is desirable to comprehensively cut off the current of the abnormal battery, and can typically be executed according to the flowchart shown in FIG. .
[0021]
Hereinafter, the flowchart illustrated in FIG. 2 will be described in the order of processes.
First, in process 1 (hereinafter abbreviated as [P1]), the voltage of each unit cell 1 is measured. For example, when an abnormality such as an internal short circuit occurs, the abnormality is detected by the voltmeter 2 as a voltage abnormality of the unit cell.
Next, it is determined whether the voltage detected by the voltmeter 2 is an abnormal voltage (in the case of this battery, when it exceeds 4.3 V or less than 1.5 V) [P2]. When the detected voltage is within such a range (Yes: 1.5 to 4.5 V), normal use is continued.
[0022]
When the detected voltage is an abnormal voltage (when No: when it exceeds 4.3 V or when it is less than 1.5 V), a signal is sent from the switch controller 9 connected to the voltmeter 2 to the switch 4 of the bypass circuit 3. The switch is closed (P3).
When the switch 4 of the bypass circuit 3 is closed, a current flows through the bypass circuit 3 where no current normally flows [P4]. Since the current value at this time is more than twice the maximum load current value during normal use and is a current value sufficient to blow the fuse 6, the fuse 6 is blown and the series battery group 7 is opened. [P5].
[0023]
In addition, the series battery group including the abnormal battery keeps flowing the current through the bypass circuit even after the fuse is blown, so that the voltage gently reaches 0V, and thereafter does not function as a battery [P6].
On the other hand, other series battery groups that do not include abnormal cells do not have any effect, so the maximum output that can be used as a vehicle is reduced, but the vehicle can still be driven and moved to a safe place. It is possible to perform repair or the like [P7].
[0024]
As described above, the assembled battery can flow a sufficient current to fuse the fuse safely and securely, and the fuse connected in series to the series battery group and the bypass circuit can be surely blown, Only the series battery group including the abnormal battery can be disconnected from the parallel circuit.
In addition, since the series battery group including the abnormal battery continues to pass the current through the bypass circuit even after the fuse is blown, the voltage reaches 0V gently, and the abnormal battery can be safely processed.
Furthermore, since energization to the series battery group other than the series battery group including the abnormal battery is maintained, the vehicle can be traveled thereafter.
Furthermore, the bypass circuit can also be used for battery capacity variation adjustment during normal use.
Moreover, since the said assembled battery can ensure large output and a large capacity | capacitance, it is not restricted to the battery for hybrid vehicles, It can be used also for the electric power supply source for electric vehicles with high reliability.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to detect battery abnormality even in a battery parallel circuit, and when abnormality occurs in the battery, the abnormality is detected by a voltmeter, etc. Since a large current is passed through the current bypass circuit connected in parallel to the battery and the circuit is reliably shut off, abnormalities such as micro short-circuits that occur in the battery are reliably detected, abnormal batteries are disconnected from the system, and abnormal Thus, it is possible to provide an assembled battery that can secure the minimum necessary power without causing the adverse effect of the battery that has occurred on other parallel batteries.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of an assembled battery of the present invention.
FIG. 2 is a flowchart showing a method for interrupting current of the abnormal battery in the embodiment of FIG. 1;
[Explanation of symbols]
1 Cell 2 Voltmeter 3 Current Bypass Circuit 4 Switch 5 Resistor 6 Fuse 7 Series Battery Group 8 Assembly Battery 9 Switch Controller

Claims (8)

In a battery pack in which batteries are connected in parallel,
Means for detecting abnormality of the battery, means for controlling energization, a current bypass circuit having a resistor connected in parallel to each of the batteries, and an overcurrent connected in series to the bypass circuit and the battery And a means for electrically interrupting the circuit.  The assembled battery according to claim 1, wherein the battery is a battery group in which a plurality of single cells are connected in series.  The means for detecting an abnormality of the battery detects a part or all of the voltage of the series battery group with a voltmeter, and determines that the abnormality is detected when the voltage exceeds a predetermined value. The assembled battery as described.  The assembled battery according to any one of claims 1 to 3, wherein the means for controlling energization is a switch, and the means for electrically interrupting the circuit by the overcurrent is a fuse.  The voltmeter is installed for each battery, and when any of the batteries shows a voltage of a predetermined value or more, the voltmeter connected in parallel to the battery detects the voltage, and the bypass circuit The assembled battery according to claim 3 or 4, wherein a signal is sent to the switch to close the bypass circuit. The average voltage of the unit cells is V (V), its internal resistance is rc (Ω), the number of series connections of the series battery group is m (pieces), the number of parallel connections of the assembled batteries is n (pieces), and the normal time When the maximum load current is (Imax), the capacity of the fuse is 2Imax, and the resistance value of the bypass circuit is (mV / 2Imax) − (rcm / n) (Ω) or less. The assembled battery as described in any one of Claims 2-5.  The assembled battery according to any one of claims 2 to 6, wherein a lithium ion secondary battery using lithium manganate as a positive electrode and carbon as a negative electrode is used as the unit cell. In an assembled battery in which a series battery group in which a plurality of single cells composed of lithium ion secondary batteries using lithium manganate as a positive electrode and carbon as a negative electrode are connected in series is connected in parallel,
Abnormality detection means for detecting a voltage of a part or all of the series battery group with a voltmeter, and determining that the voltage is abnormal when the voltage deviates from a predetermined value;
A current bypass circuit having a switch and a resistor and connected in parallel to each of the series battery groups;
An assembled battery for a vehicle comprising a fuse connected in series to the bypass circuit and the series battery group.

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