JP2006174664A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the possibility of inadequate reliability and very expensive constitution for the case of conventional protective circuit, in which the switch-on current to the battery becomes tens to 100 A or higher for a battery type power tool or battery-type electric cleaner having a high-output motor as the load. <P>SOLUTION: A current fuse 2 is provided in a discharge circuit and a semiconductor switching element 7 or an electromagnet type contactor controlled by a control means 3 is arranged, on the terminal side farther away from a secondary battery 1 and the current fuse 2. In this constitution, a positive-side charge and discharge terminal 4 and a negative-side discharge terminal 6 can be short-circuited by the semiconductor switching element 7 or the electromagnet type contactor, so that a low cost battery pack with high reliability can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack using a current interrupt circuit that interrupts an output circuit of a secondary battery pack.

Rechargeable batteries, especially sealed secondary batteries, can be dangerous due to leakage of electrolyte or release of flammable gas when overcharged, overdischarged or reverse charged. It is known that For this reason, an electromagnetic contactor, a semiconductor switching element, etc. are generally arranged as a current circuit switching element for stopping charging / discharging by opening the circuit in a circuit for charging / discharging the secondary battery. In particular, in a lithium secondary battery that is highly dangerous during overcharge or overdischarge, in many cases, these current circuit switching elements are built in the battery pack. In addition, as a means of battery protection whose main purpose is to prevent overcharging from the viewpoint of double protection, a semiconductor switching element installed between the positive and negative terminals by a thyristor or the like when the battery voltage exceeds a predetermined value Has been proposed (for example, see Patent Document 1).
JP 2002-095157 A

  However, in the conventional configuration, in the case of a battery type power tool or a battery type vacuum cleaner having a high output motor as a load, an energization current to the battery ranges from several tens of amperes to 100 amperes or more. Current interrupting elements such as electromagnetic contactors and semiconductor switching elements to be installed in the circuit board are required to have low internal resistance and high reliability, which are very large and expensive. In addition, since an instantaneous surge current due to the back electromotive force when the motor is stopped flows, the protection circuit using a thyristor or the like as disclosed in Patent Document 1 has a very high possibility of malfunction. The present invention proposes an inexpensive and highly reliable current interruption circuit in such a battery pack that requires high output.

  In order to achieve the above object, the battery pack of the present invention monitors one or a plurality of secondary batteries, a positive charge / discharge terminal, a negative charge terminal, a negative discharge terminal, and the state of the secondary battery. And a control means for controlling, a current fuse is disposed in the discharge circuit, and a semiconductor switching element or an electromagnetic contactor controlled by the control means is provided at a position closer to the terminal than the secondary battery and the current fuse. The positive charge / discharge terminal and the negative discharge terminal can be short-circuited by the semiconductor switching element or the electromagnetic contactor.

In the present invention, the discharge terminal to which a large current is applied and the charging terminal to which a large current is not applied, such as during discharging, are separated. A current interrupting element such as a semiconductor switching element can be installed. On the other hand, in a discharge circuit in which these elements are difficult to install, a control means for monitoring and controlling the state of the battery detects an overcharge from this discharge terminal or is expected to cause an overdischarge. The battery is short-circuited by operating a semiconductor switching element or electromagnetic contactor located inside the negative discharge terminals and outside the secondary battery and fuse, and the current fuse is blown by passing an excessive short-circuit current. So the circuit is safely shut off. Furthermore, according to this circuit configuration, the semiconductor switching element or the electromagnetic contactor is energized only when the discharge circuit is interrupted, and is not energized at all during normal operation, so the power consumption of the control circuit can be greatly reduced. It becomes. Furthermore, since these elements do not normally operate, the required value of the repeated life is small, and therefore, an element having sufficient reliability for this application can be obtained at a lower cost than an element that directly opens and closes the discharge circuit. .

  As described above, according to the present invention, it is possible to provide a discharge circuit for abnormal use such as overcharge of a secondary battery without providing a current interruption means such as a semiconductor switching element or an electromagnetic contactor in a discharge circuit that requires energization of a large current. It becomes possible to block.

  In addition, the determination of abnormality does not depend only on a simple battery voltage or temperature, but is performed by calculation in the control means, so that a reliable determination without malfunction can be made. Furthermore, semiconductor switching elements and electromagnetic contactors that short-circuit between the positive side discharge terminal and the negative side discharge terminal do not operate during normal use, and thus do not consume power.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  FIG. 1 shows the configuration of a circuit according to an embodiment of the present invention. 1 is a secondary battery such as a lithium ion secondary battery, 2 is a current fuse that interrupts charging / discharging of the secondary battery 1, and 3 is voltage / temperature information of the secondary battery 1 and information from a current sensor 10 and the like. Control means for performing charge / discharge control, 4 is a positive charge / discharge terminal, 5 is a negative charge terminal, and 6 is a negative discharge terminal. 7 is a semiconductor switching element that receives a signal from the control means 3 and short-circuits the secondary battery 1, 8 is a temperature sensor for measuring the ambient temperature of the secondary battery 1 and sending information to the control means 3, and 9 is a control means A charging circuit switching semiconductor switching element 10 that receives a signal from 3 and stops charging the secondary battery 1 is a current sensor that measures the value of the current flowing to the secondary battery 1.

  A current fuse 2 is connected to the secondary battery 1 connected between the positive side charge / discharge terminal 4 and the negative side discharge terminal 6. The control means 3 monitors the temperature of the secondary battery 1 with the temperature sensor 8 and also monitors the voltage. Further, the current sensor 10 monitors the charge / discharge current. A charging circuit comprising a negative charging terminal 5 and a charging circuit switching semiconductor switching element 9 controlled by the control means 3 is provided in parallel with the discharging circuit. The discharge circuit is connected at a position closest to the terminal of the circuit via the semiconductor switching element 7 controlled by the control means 3. Although the current fuse 2 is connected to the positive side of the secondary battery 1, it functions in the same manner even if it is connected to the negative side of the discharge circuit.

  Hereinafter, a series of operations according to this configuration will be described. At the time of charging, charging current is supplied from the positive side charging / discharging terminal 4 and the negative side charging terminal 5. Normally, the charger measures the voltage between the positive charge / discharge terminal 4 and the negative charge terminal 5 to prevent the secondary battery 1 from being overcharged. However, when energization is continued due to a failure of the charger, the control means 3 detects overcharge to the secondary battery 1 based on the voltage of the secondary battery 1 and the temperature detected by the temperature sensor 8. The charging can be stopped by opening the charging circuit switching semiconductor switching element 9.

On the other hand, since only the discharge is normally performed from the plus-side charge / discharge terminal 4 and the minus-side discharge terminal 6, such protection against overcharge becomes unnecessary. However, it is important to ensure safety even when the battery is charged from the discharge circuit by an incorrect usage method. In this way, when charging is performed from the plus side charge / discharge terminal 4 and the minus side discharge terminal 6, the control means 3 moves to the secondary battery 1 based on the voltage of the secondary battery 1 or the temperature detected by the temperature sensor 8. Is detected, the semiconductor switching element 7 is activated. As a result, the secondary battery 1 is short-circuited via the semiconductor switching element 7, an excessive current flows through the current fuse 2, and the circuit is opened when the current fuse 2 is blown, so that charging from the discharge circuit is stopped and the battery Is safe.

  In the present embodiment, the charging circuit and the discharging circuit are separated, and the minus side charging terminal 5 and the minus side discharging terminal 6 are provided separately, but the charging circuit and the discharging circuit are not separated. You can also. In this case, only one terminal may be provided as the negative charge / discharge terminal.

  Even in this case, protection against normal overdischarge can be performed by opening and closing the charging circuit switching semiconductor switching element 9. When the battery is charged by an incorrect usage method such as reverse connection or when the control means 3 outputs a signal to open the charging circuit switching semiconductor switching element 9, the secondary battery The semiconductor switching element 7 is operated from the control means 3 based on the voltage 1 and the temperature detected by the temperature sensor 8. As a result, the secondary battery 1 is short-circuited via the semiconductor switching element 7, an excessive current flows through the current fuse 2, and the circuit is opened when the current fuse 2 is blown, so that the safety of the battery can be protected.

  The secondary battery pack of the present invention is useful as a battery pack using a current interrupt circuit that interrupts the output circuit of the secondary battery pack because it has simple and high reliability and consumes very little power.

The figure which shows an example of the electric current interruption circuit concerning this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Current fuse 3 Control means 4 Positive side charge / discharge terminal 5 Negative side charge terminal 6 Negative side discharge terminal 7 Semiconductor switching element 8 Temperature sensor 9 Charging circuit switching semiconductor switching element 10 Current sensor

Claims (2)

A battery pack comprising one or more secondary batteries, a positive charge / discharge terminal, a negative charge terminal, a negative discharge terminal, and a control means for monitoring and controlling the state of the secondary battery. ,
The semiconductor switching element or the electromagnetic contactor includes a semiconductor switching element or an electromagnetic contactor controlled by the control means at a position closer to the terminal side than the secondary battery and the current fuse. The battery pack is characterized in that the plus-side charge / discharge terminal and the minus-side discharge terminal can be short-circuited. A battery pack comprising one or a plurality of secondary batteries, a positive charge / discharge terminal, a negative charge / discharge terminal, and a control means for monitoring and controlling the state of the secondary battery,
A current fuse is disposed in the charge / discharge circuit, and a semiconductor switching element or an electromagnetic contactor controlled by the control means is provided at a position closer to the terminal than the secondary battery and the current fuse, and the semiconductor switching element or the electromagnetic contactor A battery pack characterized in that the positive charge / discharge terminal and the negative charge / discharge terminal can be short-circuited by a contactor.