JPH0799064A - Storage battery device - Google Patents

Abstract

PURPOSE:To avoid the breakage of a three-terminal regulator even when the terminal voltage of a storage battery is in an excessive high voltage condition, by adding an excessive voltage protective circuit with a simple circuit structure. CONSTITUTION:When the terminal voltage of a Ni-Cd storage battery 1 rises, the reverse direction voltage of the Zener diode 6a of an excessive voltage protective circuit 6 rises to the Zener voltage, and the emitter voltage of an NPNTr 6b also rises. But the reverse direction voltage of the diode 6a does not rise more than the Zener voltage even though the terminal voltage of the battery 1 rises further. As a result, the power source fed to a three-terminal regulator 7 is made lower than a specific voltage constantly. The regulator 7 feeds the power source fed through the circuit 6 to the power source input terminal VDD of a battery data detecting circuit 2 by making into a constant voltage power source stabilized further. And the circuit 6 can be composed of simple elements including diodes 6a and Tr 6b, resistances R1 to R3, and a capacitor C1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery device equipped with a nickel cadmium storage battery or the like.

[0002]

2. Description of the Related Art A storage battery device equipped with a nickel-cadmium storage battery is provided with a battery information detection circuit for detecting battery information such as terminal voltage, charge / discharge current and integrated battery capacity of the nickel-cadmium storage battery. . The cumulative battery capacity is obtained by adding the charging capacity obtained by integrating the charging current with time and repeating the integration of subtracting the discharging capacity obtained by integrating the discharging current with time. It becomes possible to represent the actually stored battery capacity.

The above-mentioned conventional battery information detection circuit receives a constant voltage power supply directly from a nickel-cadmium storage battery of a storage battery device via a three-terminal regulator. The 3-terminal regulator is an IC [Integrated] constant voltage power supply circuit composed of a feedback series path regulator circuit.
Circuit] is a circuit integrated. Since such a three-terminal regulator can easily configure a power supply circuit with good performance, it is frequently used as a constant voltage power supply circuit for other electronic devices and the like.

[0004]

However, in the case of the storage battery device, since it is necessary to charge the nickel-cadmium storage battery, the terminal voltage of the nickel-cadmium storage battery becomes a voltage considerably higher than the rated voltage during this charging. . Moreover, when the electrolyte solution is consumed due to overcharging or the like and the nickel cadmium storage battery is dried up, the terminal voltage during charging is further increased due to an abnormal increase in internal resistance. However, since the three-terminal regulator is a general-purpose component, the input withstand voltage cannot be particularly increased only when it is used in a storage battery device.

Therefore, in the conventional storage battery device, the input voltage of the three-terminal regulator that supplies the constant voltage power supply to the battery information detection circuit may be an excessively high voltage during charging, and the three-terminal regulator is easily destroyed. There was a problem of becoming. Note that this problem is common not only to the storage battery device having the nickel-cadmium storage battery but also to all storage battery devices having other secondary batteries.

In view of the above circumstances, the present invention prevents the input voltage of the three-terminal regulator from becoming an excessively high voltage by supplying the voltage of the storage battery to the three-terminal regulator through the overvoltage protection circuit. It is an object of the present invention to provide a storage battery device capable of performing the above.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 is a rechargeable storage battery, and a battery information detection circuit for detecting battery information such as charging current relating to the storage battery, In a storage battery device including a three-terminal regulator that supplies a constant voltage power supply to the battery information detection circuit, a power supply from the storage battery is received, and a power supply of a predetermined voltage or less is supplied to the three-terminal regulator regardless of the level of the power supply voltage. It is characterized in that an overvoltage protection circuit for supply is provided.

According to a second aspect of the present invention, a zener voltage generating circuit for applying a terminal voltage of a storage battery to a zener diode to generate a zener voltage across the zener diode, and a zener voltage generated by the zener voltage generating circuit are bases. The overvoltage protection circuit according to claim 1 is configured by a transistor circuit in which a transistor input to the transistor is an emitter follower connection in which a storage battery serves as a power source and an input side terminal of a three-terminal regulator serves as a load.

[0009]

With the above-described structure, the overvoltage protection circuit can supply the three-terminal regulator with a power source having a predetermined voltage or lower regardless of the power source voltage of the storage battery. Therefore, during charging, the terminal voltage of the storage battery is too high. In the case of this, the 3-terminal regulator will not be destroyed by the high voltage input. In addition, this overvoltage protection circuit
It does not need to be a constant voltage power supply circuit that requires a strictly constant voltage, and can be configured by a simple circuit using a Zener diode or the like. Therefore, instead of forming a constant voltage power supply circuit that does not require an overvoltage protection circuit with a discrete circuit that uses a transistor having a high withstand voltage, instead of an integrated three-terminal regulator, the storage circuit and the three-terminal regulator are provided. The present invention in which this overvoltage protection circuit is inserted makes it possible to configure the power supply circuit of the battery information detection circuit more easily and cheaply.

A second aspect of the present invention is a non-feedback series path regulator circuit comprising a Zener voltage generating circuit for generating a Zener voltage and a transistor circuit for controlling a power supply voltage supplied to a three-terminal regulator by the Zener voltage. It shows a case where the above-mentioned overvoltage protection circuit is configured. Such an overvoltage protection circuit is
It can be configured by a simple circuit in which a zener diode and a resistor and a capacitor that are appropriately inserted in the transistor are added.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 show an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a storage battery device, and FIG. 2 shows a more specific configuration of the overvoltage protection circuit in FIG. It is a circuit block diagram shown.

In this embodiment, a storage battery device having a nickel-cadmium storage battery and a battery information detection circuit composed of a one-chip microcomputer will be described.

As shown in FIG. 1, this storage battery device has a battery information detection circuit 2 housed in a case together with a nickel-cadmium storage battery 1. The nickel-cadmium storage battery 1 has a plurality of cells connected in series so as to obtain a predetermined voltage. The positive electrode is connected to the positive electrode terminal 3 of the storage battery device, and the negative electrode is connected to the negative electrode via the shunt resistor 4. It is connected to terminal 5. The storage battery device is charged and discharged through the positive electrode terminal 3 and the negative electrode terminal 5. The shunt resistor 4 is a very low resistance resistor having a resistance value of about several mΩ, and plays a role of a galvanic detector for detecting the magnitude of the current flowing therethrough.

The battery information detection circuit 2 is a circuit consisting of a one-chip microcomputer and its peripheral circuits, and determines the charging / discharging current value by the terminal voltage value of the nickel-cadmium storage battery 1 and the voltage drop generated in the shunt resistor 4. You can enter. Then, the battery information detection circuit 2 obtains the charge capacity and the discharge capacity by time-integrating the value of the input charge / discharge current, and at the same time, integrates the charge capacity and the discharge capacity to obtain the nickel-cadmium storage battery 1. An integrated battery capacity indicating the actually stored battery capacity is calculated. When the value of the input terminal voltage is abnormally low, the number of short-circuited cells is detected by determining that the voltage has dropped due to a cell short circuit,
When the value of this terminal voltage is abnormally high, dry-up is detected. Further, the battery information detection circuit 2 can detect other various battery information. The battery information detected by the battery information detection circuit 2 is stored in the RAM [Random Access Memory] in the battery information detection circuit 2.
And EEPROM [Electrically Erasable Programmable
[Read-Only Memory].

As shown in FIG. 1, the battery information detection circuit 2 receives power from the nickel-cadmium storage battery 1 via an overvoltage protection circuit 6 and a three-terminal regulator 7.

The overvoltage protection circuit 6, as shown in FIG.
It is composed of a non-feedback type series path regulator circuit using a Zener diode 6a and an NPN transistor 6b. That is, the overvoltage protection circuit 6 has a series circuit of a resistor R1 connected between both electrodes of the nickel-cadmium storage battery 1 (including the shunt resistor 4 but ignored here) and a Zener diode 6a in the reverse direction. There is. Therefore, the terminal voltage of the nickel-cadmium storage battery 1 is divided by the voltage drop at the resistor R1 and the reverse voltage of the Zener diode 6a, and even when this terminal voltage becomes an abnormally high voltage, Diode 6a
The reverse voltage of does not exceed the Zener voltage. A capacitor C1 for eliminating noise is connected in parallel to the Zener diode 6a.

The anode of the Zener diode 6a is connected to the NPN transistor 6 via the base resistor R2.
It is connected to the base of b. The NPN transistor 6b has a collector connected to the positive electrode of the nickel-cadmium storage battery 1 and an emitter connected to the input terminal IN of the three-terminal regulator 7 via the emitter resistor R3. Therefore, this NPN transistor 6b
Becomes an emitter follower connection, and the base voltage is regulated by the Zener voltage of the Zener diode 6a. The output terminal O of the three-terminal regulator 7
The UT is connected to the power input terminal VDD of the battery information detection circuit 2. A capacitor C2 for reducing the output impedance for high frequencies is connected between the output terminal OUT of the three-terminal regulator 7 and the ground terminal GND.

In the overvoltage protection circuit 6 having the above construction, the emitter follower-connected NPN transistor 6b is driven by the reverse voltage of the Zener diode 6a which divides the terminal voltage of the nickel-cadmium storage battery 1 by the resistor R1.
Power will be supplied to the terminal regulator 7. Here, if the emitter voltage of the NPN transistor 6b rises, the base current decreases, so that the rise of the emitter voltage is suppressed, whereby the three-terminal regulator 7
It is possible to supply a power source having a substantially constant voltage according to the terminal voltage. Further, if the terminal voltage of the nickel-cadmium storage battery 1 rises, the reverse voltage of the Zener diode 6a rises up to the Zener voltage, and NP
The emitter voltage of the N-transistor 6b also rises. However, the reverse voltage of the Zener diode 6a is
Even if the terminal voltage of the nickel-cadmium storage battery 1 further rises, it does not rise above the Zener voltage. Therefore, even if the terminal voltage of the nickel-cadmium storage battery 1 becomes abnormally high at the time of charging, the base voltage of the NPN transistor 6b is regulated by this Zener voltage and does not rise further, so that it is supplied to the three-terminal regulator 7. The supplied power is always below a predetermined voltage.

The three-terminal regulator 7 uses the power supplied through the overvoltage protection circuit 6 as a more stable constant voltage power supply, and the power input terminal V of the battery information detection circuit 2.
Can be supplied to DD.

As a result, according to the storage battery device of this embodiment, even if the terminal voltage of the nickel-cadmium storage battery 1 becomes abnormally high due to dry-up during charging, the overvoltage protection circuit 6 sets this voltage at a predetermined level. Since the voltage is lowered to the voltage, there is no fear that the three-terminal regulator 7 will be destroyed by the high voltage input. Further, since this overvoltage protection circuit 6 is composed of a simple circuit in which resistors R1 to R3 and a capacitor C1 are added to the Zener diode 6a and the NPN transistor 6b, the integrated circuit 3 is integrated.
It is possible to configure the power supply circuit of the battery information detection circuit 2 more easily and cheaply than when the terminal regulator 7 is formed by a discrete circuit using a transistor having a high withstand voltage and a feedback operational amplifier (operational amplifier). Become.

[0022]

As is apparent from the above description, according to the storage battery device of the present invention, the terminal voltage of the storage battery becomes an excessively high voltage at the time of charging simply by adding the overvoltage protection circuit having a simple circuit configuration. Also in the case of the above, there is an effect that the three-terminal regulator is not destroyed by the high voltage input.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a storage battery device, showing an embodiment of the present invention.

2 is a circuit block diagram showing an embodiment of the present invention and showing a more specific configuration of the overvoltage protection circuit in FIG. 1. FIG.

[Explanation of symbols]

 1 Nickel-cadmium storage battery 2 Battery information detection circuit 6 Overvoltage protection circuit 6a Zener diode 6b NPN transistor 7 3-terminal regulator

Claims (2)

[Claims] 1. A rechargeable storage battery, a battery information detection circuit for detecting battery information such as a charging current relating to the storage battery, and a constant voltage power supply for the battery information detection circuit.
In a storage battery device having a terminal regulator, an overvoltage protection circuit is provided, which receives power supply from the storage battery and supplies a power supply of a predetermined voltage or less to the three-terminal regulator regardless of whether the power supply voltage is high or low. Storage battery device. 2. A Zener voltage generating circuit for applying a terminal voltage of a storage battery to a Zener diode to generate a Zener voltage across the Zener diode, and a transistor to which the Zener voltage generated by the Zener voltage generating circuit is input to a base. 2. The storage battery device according to claim 1, wherein the overvoltage protection circuit according to claim 1 is constituted by a transistor circuit in which the storage battery serves as a power source and the input side terminal of the three-terminal regulator serves as a load.