JPH0797893B2 - Peak voltage detection circuit in charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a charging device for a battery to be charged, a first delay circuit composed of a capacitor and a resistor is connected to both ends of a resistor for generating a voltage proportional to the charging voltage of the battery to be charged. A second delay circuit is further connected to the capacitor of the first delay circuit, and first and second discharge circuits composed of a diode and a resistor are provided to accelerate the discharge time of the capacitor in the delay circuit after completion of charging. It is possible to prevent erroneous detection of an operational amplifier that detects the completion of charging of a storage battery to be charged, reduce the number of steps for charging, and allow another storage battery to be charged immediately after the completion of charging of the storage battery.

[Industrial application field]

TECHNICAL FIELD The present invention relates to an improvement of a peak voltage detection circuit of a charging voltage in a charging device for a storage battery used in various electric circuits.

In the above charging of the storage battery, it is possible to prevent erroneous detection when detecting the completion of charging of the storage battery, to reduce the number of steps for charging, and to successively charge a plurality of storage batteries in a short time. Is desirable.

[Conventional technology]

FIG. 3 is a diagram of a storage battery auxiliary charging device using a conventional peak voltage detection circuit.

FIG. 4 is a diagram showing the characteristics of the input voltage of the operational amplifier that detects the completion of charging when the storage battery is charged.

FIG. 5 is a diagram of a storage battery charging device used in combination with the conventional device of FIG.

In FIG. 3, when the switch 6 is turned on, the charging power source 7 starts charging the rechargeable storage battery 8 via the resistor R. In addition, in order to support the charging voltage of such a storage battery to be charged, a low resistance R ₁ and a Zener diode D ₁ are connected in parallel with the storage battery.
When a charging voltage exceeds the reverse voltage of the Zener diode D ₁ and a series circuit is connected, a voltage corresponding to the charging voltage is generated in the resistor R ₁ . Furthermore, in order to reduce the input voltage to the operational amplifier 2, the series circuit of the capacitor C ₁ and the diode D ₂ is connected as shown in the figure, and the currents i ₁ and i ₂ start to flow. Then, it is known that an input voltage having a voltage characteristic as shown in FIG. 4 is generally given to the input terminal of the operational amplifier corresponding to the voltage across the storage battery 8.

In FIG. 4, among the characteristics of the input voltage to the operational amplifier corresponding to the charging voltage of the storage battery, the solid line shows the characteristics of the input voltage when the storage battery is normally charged, and the dotted line shows, for example, the battery left discharged for a long time. It is an input voltage characteristic to an operational amplifier at the time of charging a storage battery such as an abnormal storage battery.

That is, when charging a normal storage battery, the terminal voltage of the storage battery rises with the progress of charging, but in the case of an abnormal storage battery, the charging voltage temporarily rises immediately after the start of charging, then drops and then rises, and thereafter. It takes almost the same process as the charge characteristic of a normal storage battery.

Therefore, when the normal storage battery is charged, the input voltage to the operational amplifier is generated after the charging voltage exceeds the reverse voltage of the Zener diode D ₁ , and the input voltage is up to the fully charged state of the storage battery in FIG. Since it rises as shown in I), the operational amplifier is in the ON state during this period, and the ON output causes the switch drive circuit to keep the switch 6 in the closed state, and after the input voltage reaches the peak value V _P corresponding to full charge. When the input voltage changes in the negative direction, the operational amplifier is turned off, the switch 6 is opened again by the control of the switch drive circuit,
Charging of the storage battery is completed.

On the other hand, when the voltage of the storage battery before charging is higher than the reverse voltage of the Zener diode D ₁ when charging the abnormal storage battery, the input voltage to the operational amplifier is indicated by the dotted line in the input voltage characteristic (II) of FIG. As shown in the figure, an abnormal peak V ₁ is shown at the initial stage of charging, and after that, the voltage changes temporarily in the negative direction.Thus, due to this change in the negative direction, the operational amplifier that had been in the on-state output until then becomes the off-state. The switch drive circuit 5 opens the switch.

Therefore, the storage battery 8 cannot be charged up to the peak value V _p of the input voltage value to the operational amplifier. In order to avoid this, as shown in FIG. 5, the constant current source 9 charges the storage battery 8 for a predetermined time (for example, t _{1 in} FIG. 4) by the timer 11, and then the circuit shown in FIG. The storage battery 8 was connected to charge the storage battery up to the rated value.

[Problems to be solved by the invention]

However, in the above-described conventional peak voltage detection circuit, two circuits must always be prepared, and there is a problem that the number of steps for charging becomes large.

Also, when one storage battery is charged and another storage battery is charged after a short time, the internal impedance between the resistor R ₁ and the two input terminals of the operational amplifier 2 with respect to the charge charged in the capacitor C ₁ However, since the internal impedance value is extremely large, it takes a long time to discharge, and there is a problem that the next storage battery cannot be charged until the discharge is completed.

[Means for solving problems]

According to the present invention, the above-mentioned problem is caused by the present invention. A peak in a charging device in which a switch connected in series to a power source for charging a battery to be charged is controlled by an output of an operational amplifier via a switch drive control circuit as shown in FIG. In the voltage detection circuit, the resistor R ₁ that configures the series circuit connected in parallel with the battery to be charged together with the Zener diode D ₁ in the blocking direction has the first delay circuit composed of the resistor R ₂ and the capacitor C _2. The circuit is connected, and the diodes D ₂ and D _{5 in} opposite directions are connected in parallel between the two input terminals of the operational amplifier, and the one input terminal is
Connect the resistor R ₂ of the first delay circuit and the capacitor C ₂ to the connection point via the second delay circuit consisting of the series circuit of the resistor R ₅ and the capacitor C _3, and connect the other input terminal to the other end of the capacitor C _2. The resistor R ₂ of the first delay circuit has a first discharge circuit formed of a series circuit of a diode D ₃ and a resistor R ₃ in the blocking direction, and a series circuit of a diode D ₄ and a resistor R _{4 in the} blocking direction. The peak voltage detection circuit in the charging device is characterized in that the series circuit of the second discharging circuit and the resistor R ₅ of the second delay circuit is connected in parallel.

[Action]

That is, in the present invention, in the peak voltage detection circuit at the rear of the battery to be charged, the first delay circuit including the series circuit of the resistor R ₂ and the capacitor C _2, and the first delay circuit including the series circuit of the resistor R ₅ and the capacitor C ₃ . 2 delay circuit, a first discharge circuit consisting of a series circuit of a diode D ₃ and a resistor R ₃ , a second discharge circuit consisting of a series circuit of a diode D ₄ and a resistor R _4, and a discharge path of an operational amplifier by a diode D ₅ . It is provided in the front position.

By increasing the capacitances of the capacitors C ₂ and C ₃ in the first and second delay circuits, the input voltage characteristic of the operational amplifier corresponding to the initial charging voltage in the storage battery has a gentle slope.

This allows, for example, a storage battery that has been left for a long time after being discharged,
Moreover, when the voltage in the uncharged state is higher than the reverse voltage of the Zener diode D ₁ , even if there is an abnormal peak due to a temporary increase in the charging voltage immediately after the start of charging, the abnormal peak portion is generated by the delay circuit according to the present invention. Has a gradual voltage characteristic and is input to the operational amplifier without any negative voltage change in the middle, so the operational amplifier remains on until the storage battery is fully charged. False detection of the operational amplifier is prevented.

Further, after the charging of one storage battery is completed, the charges of the capacitors C ₂ and C ₃ of the first and second delay circuits are immediately discharged through the first discharging circuit and the second discharging circuit. Therefore, when the next battery to be charged is charged, the first and second delay circuits are in a state in which they can fully exercise their functions, so that charging is immediately performed.

〔Example〕

The function of FIG. 1 as an embodiment according to the present invention will be described in more detail.

In FIG. ₁ , a series circuit of a resistor R ₁ having a small resistance value and a Zener diode D ₁ is connected in parallel to the storage battery (8) to be charged, and when the charging voltage exceeds the reverse voltage of the Zener diode D ₁ , the resistor R 1 _{At 1} , a voltage proportional to the voltage of the rechargeable battery is generated.

In the present invention, a series circuit including a resistor R ₂ and a capacitor C ₂ as a first delay circuit is connected in parallel with the resistor R ₁ .

A series circuit composed of a resistor R ₅ and a capacitor C ₃ as a second delay circuit is further connected to a connection point between the resistor R ₂ and the capacitor C ₂ in the first delay circuit, and the other end of the series circuit is operated. It is connected to one input terminal of the amplifier and the other input terminal is connected to the other end of the capacitor C ₂ .

On the other hand, between the two input terminals of the operational amplifier 2, diodes D ₂ and D _{5 in} opposite directions are connected in parallel.
D ₅ fulfills a part of the function of the discharge path in the present invention.

The discharging circuit according to the present invention includes a first discharging circuit including a series circuit of a blocking diode D ₃ and a resistor R ₃ and a second discharging circuit including a series circuit of a blocking diode D ₄ and a resistor R _4. It is provided, with respect to the resistance R _2, a first discharge circuit, and the second discharge circuit is connected in parallel via the resistor R _5.

In the configuration as shown in FIG. 1, when the switch 6 is pressed to charge the storage battery 8, the storage battery 8 is charged by the charging power source 7 via the switch 6 and the resistor R, and the zener diode D ₁ is reversely charged. When the charging voltage exceeds the directional voltage, a voltage proportional to that voltage is generated across the resistor R ₁ .

Then, the voltage at the resistor R ₁ charges the capacitor C ₂ of the first delay circuit, and then the capacitor C ₃ through the resistor R ₅ of the second delay circuit.

Thus, the voltage corresponding to the charging voltage to the storage battery 8 is the resistance
Although appearing at both ends of R ₁ , the input voltage to the operational amplifier corresponding to this voltage has a smooth slope until the charging of the capacitors C ₂ and C ₃ is completed, as shown in FIG. Become.

For this reason, among storage batteries to be charged, for example, a storage battery that has been left discharged for a long period of time and is charged when the voltage in the uncharged state is higher than the reverse voltage of the Zener diode D _1. Even if there is an abnormal peak of the voltage in the initial stage, the abnormal peak and the voltage change in the negative direction do not occur in the input voltage to the operational amplifier.

Therefore, the operational amplifier continues to be in the ON state, reaches the peak value V _P of the input voltage corresponding to the full charge of the storage battery, and is turned off by the voltage change in the negative direction.

That is, when charging of the battery to be charged is completed, the operational amplifier is turned off to detect the completion of charging, and by this output turning off, the switch drive circuit sets the switch 6 to the open state again, and the charging power supply circuit is disconnected.

When the charged battery to be charged is removed, the charge of the capacitor C ₂ of the first delay circuit passes through the first discharge circuit and the resistor R _1, and the charge of the capacitor C ₃ of the second delay circuit changes to the second charge. Immediately discharges through the discharge circuit, resistor R ₁ and diode D ₅ .

Therefore, as soon as a new battery to be charged is connected, this battery can be charged by pressing the switch 6 again.

The gently sloping portion in the characteristic of FIG. 2 can be formed in a desired shape by appropriately selecting the capacitance values of the capacitors C ₂ and C ₃ of the first and second delay circuits.

That is, according to the present invention, even in the case of charging a storage battery that causes an abnormal peak during charging, the operational amplifier does not malfunction due to the abnormal peak, and after the charging of the storage battery is completed, another storage battery is charged. Before, the capacitor in the delay circuit according to the present invention is immediately discharged by the discharge circuit according to the present invention, so that the charging operation for a new storage battery can be immediately performed.

〔The invention's effect〕

As described above, according to the present invention, erroneous detection of the operational amplifier at the time of charging the battery to be charged is prevented, the number of steps for charging is reduced, and the other batteries are sequentially charged in a short time. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an input voltage characteristic to an operational amplifier corresponding to a charging voltage of a storage battery in the embodiment, and FIG. FIG. 4 is a diagram showing the input voltage characteristic of the operational amplifier corresponding to the charging voltage of the storage battery to be charged in the circuit of FIG. 3, FIG. 5 is the peak voltage detection circuit diagram of the charging device of the example, and FIG. It is a figure of the charging device of the storage battery of the prior art example used in combination. In the figure, 1 is a charger, 2 is an operational amplifier, 3 is a delay circuit, 4 is a discharge circuit, 5 is a switch driving circuit, 6 and 10 are switches, 7 is a power source for charging, 8 is a storage battery to be charged, and 9 is a storage battery. Constant current source, 11 indicates a timer.

Claims (1)

[Claims] 1. A peak voltage detection circuit in a charging device in which a switch connected in series to a power supply for charging a battery to be charged is controlled by an output of an operational amplifier via a switch drive control circuit, A first delay circuit composed of a series circuit of a resistance R ₂ and a capacitor C ₂ is connected to a resistance R ₁ which forms a series circuit connected in parallel with a Zener diode D ₁ in the blocking direction, and a series circuit of a resistance R ₂ and a capacitor C ₂ is connected to the resistance R ₁ . Diodes D ₂ and D _{5 in} opposite directions are connected in parallel between the input terminals, and one input terminal is
Connect the resistor R ₂ of the first delay circuit and the capacitor C ₂ to the connection point via the second delay circuit consisting of the series circuit of the resistor R ₅ and the capacitor C _3, and connect the other input terminal to the other end of the capacitor C _2. The resistor R ₂ of the first delay circuit has a first discharge circuit composed of a series circuit of a diode D ₃ and a resistor R ₃ in the blocking direction, and a series circuit of a diode D ₄ and a resistor R _{4 in the} blocking direction. A peak voltage detection circuit in a charging device, wherein a series circuit of a second discharging circuit and a resistor R ₅ of a second delay circuit each of which is connected in parallel.