JP2004031273A - Battery voltage monitoring device and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To immediately detect an abnormality that has occurred in a secondary battery by monitoring the voltage of the secondary battery built in a battery pack, for each battery. <P>SOLUTION: The voltage monitor device comprises a battery unit 3 constituted by connecting in parallel a battery sub unit 2a, 2b in which a plurality of secondary batteries are connected in series. A voltage detecting means which detects voltages between terminals V1-V4 for each positive electrode and negative electrode of all the secondary batteries 1a-1d is provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a voltage monitoring device that monitors each voltage of a secondary battery incorporated in a battery pack, and a battery pack including the voltage monitoring device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, electric devices such as portable audio devices, mobile phones, notebook personal computers, video recorders, and digital cameras use a battery pack as a power source. Normally, a battery pack contains a plurality of chargeable / dischargeable secondary batteries, and each battery is used while repeatedly charging and discharging within a predetermined voltage range. However, the battery may be overcharged or overdischarged due to deterioration or failure of the battery. If charging and discharging are repeated in a state where the battery has deteriorated or has failed, the abnormality of the battery is promoted, and there is a risk of generating heat or the like. For this reason, various measures have conventionally been taken in order to detect the abnormality of the battery. Above all, as one of the simplest and most versatile methods for determining a battery abnormality, the output voltage of the battery has been measured.
[0003]
An example of a conventional voltage monitoring device for a battery incorporated in a battery pack will be described with reference to the accompanying drawings. FIG. 2 is a conceptual diagram illustrating an example of a conventional voltage monitoring device.
In FIG. 2, the secondary batteries 1a and 1b are connected in parallel and constitute a battery subunit 2a, and similarly, the secondary batteries 1c and 1d constitute a battery subunit 2b. These battery subunits 2a and 2b are connected in series to form a battery unit 3. The control board 4 is each battery subunit 2a, to measure the positive electrode negative between electrode terminal voltages _{V 11, V 12} of 2b. When detecting an abnormality in the battery voltage, the control board 4 stops the charging and discharging of the battery unit 3 by opening the switch element 5.
[0004]
However, when viewed from the control board 4, the individual rechargeable batteries 1a and 1b or 1c and 1d connected in parallel are not distinguished. Therefore, for example, when an abnormality occurs in which the voltage of the secondary battery 1a drops for some reason, power is supplied to the outside even from the secondary battery 1b connected in parallel to the battery having the abnormality. For this reason, the control board 4 has to detect the abnormality of the secondary battery 1a in a so-called thin state, so that there is a problem that the detection of the abnormal voltage generation by the control board 4 is delayed.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and monitors the voltage of a secondary battery included in a battery pack for each individual battery, so that abnormalities that occur in any of the secondary batteries can be prevented. The purpose is to detect immediately.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors have proposed that all of the secondary batteries in a battery unit configured by connecting a plurality of battery subunits in which a plurality of secondary batteries are connected in series are connected in parallel. And a voltage monitoring device provided with a voltage detecting means for detecting a voltage between the positive and negative terminals. Preferably, the voltage monitoring device further includes a circuit interrupting unit that stops charging and discharging of the battery unit when detecting an abnormal voltage of any of the secondary batteries based on the detection by the voltage detecting unit.
In another aspect, the present invention provides a battery unit configured by connecting a plurality of battery subunits in which a plurality of secondary batteries are connected in series, a plurality of battery subunits connected in parallel, and a positive electrode of each of all the secondary batteries. Provided is a battery pack including: a voltage detection unit configured to detect a voltage between negative electrode terminals. Preferably, the battery pack includes a circuit interrupting unit that stops charging and discharging the battery unit when detecting an abnormal voltage of any of the secondary batteries based on the detection by the voltage detecting unit.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of a voltage monitoring device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a conceptual diagram of a voltage monitoring device according to the present invention.
As shown in FIG. 1, the secondary batteries 1a and 1b are connected in series to form a battery subunit 2a, and similarly, the secondary batteries 1c and 1d form a battery subunit 2b. These battery subunits 2a and 2b are connected in parallel to form a battery unit 3. Here, the control board 4 measures the voltage between the terminals of the positive electrode and the negative electrode of each secondary battery. That is, all of the secondary battery 1a, 1b, 1c, and 1d voltage between the respective terminals _{V 1, V 2, V 3} , V 4 is measured. When detecting an abnormality in any _{one of} these inter-terminal voltages V _{1 to} V ₄ , the control board 4 opens the switch element 5 and stops charging and discharging of the battery unit 3.
[0008]
The control board 4 can detect an abnormality of each battery by comparing the voltage between the terminals with a predetermined overdischarge determination voltage and a predetermined overcharge determination voltage. In other words, at the time of discharging, it is determined that an overdischarge abnormality has occurred when the voltage between the terminals of any one of the secondary batteries has dropped to the overdischarge determination voltage. Is determined to be an overcharge abnormality.
Alternatively, the control board 4 can detect the abnormality of each battery by comparing the voltage between the terminals and monitoring whether the voltage difference is within the abnormality determination voltage. In other words, even when the voltage between the terminals is within the overdischarge overcharge determination voltage, the voltage between the terminals is compared with the other terminal voltages, and the voltage difference is further compared with a preset abnormality determination voltage. Thus, the abnormality of the battery can be determined.
[0009]
That is, in the conventional method of measuring the voltage of a plurality of secondary batteries as one unit, it is assumed that an ideal state in which the plurality of secondary batteries constituting one unit operate in the same manner. However, in reality, each secondary battery is different, and by detecting the abnormal voltage of each one, the battery pack can be operated more safely. Become. This is because if there is a plurality of rechargeable batteries, if the abnormality of one battery cannot be detected properly, the abnormal battery may generate heat, etc., and according to the present invention, such abnormal operation can be performed in a timely manner. Can be prevented.
[0010]
Further, as the switch element 5, various elements such as an element that turns on the resistor heating element by a control signal sent from the control circuit when an abnormal voltage is detected to generate heat, and melts and cuts the fuse by the generated heat can be used.
[0011]
As described above, with the voltage monitoring device according to the present invention, even when any of the secondary batteries 1a to 1d has an abnormal voltage drop, it is possible to reliably detect the abnormal voltage drop and stop charging and discharging the batteries. It is possible to minimize damage caused by battery failure.
[0012]
In the above-described embodiment of the present invention, an example has been described in which a battery unit is configured by connecting two battery subunits in which two secondary batteries are connected in series and in parallel with each other. However, the battery unit of the voltage monitoring device according to the present invention is not limited to this configuration. That is, a battery subunit may be configured by connecting a plurality of secondary batteries in series, and a battery unit may be configured by connecting a plurality of battery subunits in parallel. Further, the number of secondary batteries included in each battery subunit may be different.
[0013]
Further, as a preferred example of the control method of the control board when detecting the abnormality of the battery, an example in which the charging and discharging of the battery unit is stopped has been described. However, the preferred control method by the control base when detecting the abnormality of the battery is described. Examples thereof include blowing of a fuse and stopping of a function of a charge / discharge circuit, but a control method using a control board is not particularly limited thereto.
[0014]
Note that the voltage monitoring device according to the present invention is preferably incorporated in a battery pack together with a plurality of secondary batteries. However, all of the voltage detecting means, the abnormality detecting means, and the circuit interrupting means which constitute the voltage monitoring device do not necessarily need to be incorporated in the battery pack, but may be incorporated in electric equipment using the battery pack. For example, although not particularly limited, the voltage detecting means may be incorporated in the battery pack, and the abnormality detecting means and the circuit interrupting means may be incorporated in electric equipment using the battery pack.
[0015]
Here, the electric device is not particularly limited, but is preferably a portable device such as a portable audio device, a mobile phone, a notebook personal computer, a video recorder, and a digital camera. The secondary battery included in the battery pack is not particularly limited, but is preferably a secondary battery such as a nickel-cadmium battery, a nickel hydride battery, a lithium ion battery, and a lithium polymer battery.
[0016]
【The invention's effect】
As is apparent from the above description, the present invention provides a voltage monitoring device that monitors the voltage of a secondary battery incorporated in a battery pack for each battery, and a battery pack including the voltage monitoring device. As a result, an abnormality that has occurred in the secondary battery built in the battery pack can be immediately detected. Thereby, damage due to battery abnormality can be minimized. As a result, the voltage monitoring device and the battery pack including the voltage monitoring device according to the present invention can improve the safety of the battery and the electric equipment using the battery.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a voltage monitoring device according to the present invention.
FIG. 2 is a conceptual diagram illustrating a conventional battery voltage monitoring device.
[Explanation of symbols]
1a to 1d Secondary Battery 2 Battery Subunit 3 Battery Unit 4 Control Board 5 Switch Element

Claims (4)

Voltage detecting means for detecting the voltage between the positive and negative terminals of each of the rechargeable batteries in a battery unit configured by connecting a plurality of battery subunits in which a plurality of rechargeable batteries are connected in series in parallel. Equipped with a voltage monitoring device. The voltage monitoring device according to claim 1, further comprising a circuit interrupting unit that stops charging and discharging of the battery unit when detecting an abnormal voltage of any one of the secondary batteries based on the detection by the voltage detecting unit. A battery unit configured by connecting a plurality of battery subunits in which a plurality of secondary batteries are connected in series,
A battery pack comprising: voltage detection means for detecting the voltage between the positive and negative terminals of each of the secondary batteries. 4. The battery pack according to claim 3, further comprising: a circuit interrupting unit that stops charging and discharging of the battery unit when detecting an abnormal voltage of any one of the secondary batteries based on the detection by the voltage detecting unit. 5.

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