JPH0424761Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a charging device, and relates to one having an overcharge prevention function for charging a secondary battery such as a lead-acid battery.

(Prior Art) As a conventional charging device equipped with an overcharge prevention function, for example, the configuration shown in FIG. 3 is known.
The charging device shown in FIG. 3 includes an AC power source 1 for charging,
A battery 6 to be charged is connected to a power supply circuit 4 consisting of a transformer 2 and a rectifier circuit 3 via a first thyristor 5 for controlling charging current, and the amount of charge of the battery 6 to be charged is detected. The first thyristor 5
The second thyristor 7 provides a signal to the gate of the second thyristor 7, and a switching transistor 9 turns on and off a light emitting element 8 for indicating completion of charging.

However, this configuration requires the use of a total of three switching elements, the first and second thyristors 5 and 7, which are three-terminal switching elements, and the transistor 9, which increases the price and complicates the circuit. As a result, the probability of failure occurrence also increases.

In addition, as a conventional charging device, the Utility Model 52-100121
The configuration described in the publication is known. As shown in FIG. 4, this configuration controls the on/off control of the first thyristor 5 for controlling the charging current of the battery 6 to be charged, and the on/off control of the light emitting element 8 for indicating completion of charging. The number of three-terminal switching elements is two compared to three in the circuit shown in FIG. 3, which simplifies the circuit configuration.

(Problem to be solved by the invention) However, in the charging device shown in FIG. 4, when the second thyristor 9 is in the OFF state, the voltage applied to the gate of the first thyristor 5 is The problem is that it is determined by
That is, when the second thyristor 9 turns off, a voltage is applied to the gate circuit of the first thyristor 5, but this causes the light emitting element 8 to conduct and emit light, so that the voltage is applied to the gate of the first thyristor 5. The voltage is determined by the on-voltage of the light emitting element 8 as described above. Here, in order for the first thyristor 5 to turn on, the gate potential must be higher than the cathode potential. Therefore, the light emitting element 8
As such, it is necessary to use one whose on-voltage is higher than the voltage of the battery 6 to be charged. but,
Since the on-voltage of a light-emitting diode used as the light-emitting element 8 is usually about 2V, there are problems in that it is troublesome to select a light-emitting diode with an on-voltage corresponding to the battery voltage, and the price is also high.

An object of the present invention is to provide a charging device that has a small number of switching elements and has an overcharge prevention function that can easily handle the voltage of the battery being charged without being subject to any restrictions.

[Structure of the invention] (Means for solving the problem) The charging device according to the invention includes a charging power source for charging a battery to be charged, an anode connected to the positive side of the power source, and a cathode connected to the battery to be charged. A first thyristor connected to the negative electrode side of the power supply through a display circuit having a constant voltage element that is connected to the negative electrode side of the first thyristor and generates an output when the potential at the intermediate point exceeds a set value, and a light emitting element that emits light by the output of the constant voltage element; a charging completion detection circuit provided between the gate side of the first thyristor and the negative electrode side of the power source and outputting an output when the potential on the cathode side rises to a set value; and an output side of the charging detection circuit provided between the gate side of the first thyristor and the negative electrode side of the power supply. and a second thyristor having a gate connected to the thyristor and turned on by the output of the charge detection circuit.

(Function) In the charging device of the present invention, when the battery to be charged is not charged to a predetermined voltage, the gate potential becomes higher than the cathode potential, so voltage is applied to the gate, the first thyristor is turned on, and the battery to be charged is turned on. Charge the battery. Further, since the potential at the midpoint of the voltage dividing resistor to which one end of the display circuit is connected is also high, the constant voltage element outputs conduction, and the light emitting element emits light to indicate that charging is in progress. When charging of the battery to be charged is completed, the potential on the cathode side of the first thyristor rises, and the charging end detection circuit outputs an output to turn on the second thyristor. Therefore, the gate potential of the first thyristor becomes lower than the cathode potential and the first thyristor remains off after being turned off, and the display circuit becomes non-conductive as the constant voltage element stops outputting due to the drop in potential at the midpoint. This turns off the light-emitting element that is being charged. Furthermore, by connecting the display circuit to the midpoint of the voltage dividing resistor, the first thyristor is less likely to be affected by voltage fluctuations due to turning on and off of the light emitting element.

(Example) An example of the present invention will be described with reference to FIGS. 1 and 2 of the drawings.

The charging power source 11 connects the primary winding to the AC power source 12.
The transformer 13 has a transformer 13 connected to the transformer 13, and the anodes of diodes 14 and 15 are connected to both ends of the secondary winding of the transformer 13. These diodes 14, 15
The cathodes of the two are commonly connected and led out as a positive electrode side electric circuit of the power source 11. Further, the midpoint of the secondary winding of the transformer 13 is led out as a negative electrode side electrical path of the power source 11. Then, a pulsating output in which the sinusoidal alternating current is full-wave rectified is generated between the positive electrode side and negative electrode side electric circuits.

The first thyristor 16 has an anode connected to the positive side of the power source 11, and a cathode connected in the forward direction to the positive side terminal of a lead-acid battery 18 as a battery to be charged. Of course, the negative terminal of this lead-acid battery 18 is connected to the power supply 1.
Connect to the negative pole side of 1. 19 is a charging current control resistor, and this charging current control resistor 19 is connected in parallel with the first thyristor 16. Further, the anode side of the first thyristor 16 is connected to the gate of the first thyristor 16 via a forward diode 20, voltage dividing resistors 21 and 22, and a forward diode 23. Note that the first thyristor 1
A resistor 24 is connected between the gate of 6 and the cathode.

The display circuit 25 is constructed by connecting a Zener diode 26 as a constant voltage element, a resistor 27, and a light emitting element 28 in series, and one end is connected to the midpoint between the voltage dividing resistors 21 and 22. Further, the other end of the display circuit 25 is connected to the negative electrode side of the power source 11. Therefore, when the potential at the midpoint between the resistors 21 and 22 exceeds the voltage determined by the Zener diode 26, conduction occurs and the light emitting element 28 emits light to indicate that it is being charged.

On the other hand, the charging end detection circuit 29 includes a Zener diode 30 and a resistor 31 provided in series with the cathode of the first thyristor 16, and a resistor 33 provided between the anode of the Zener diode 30 and the second thyristor 32. , the gate of the second thyristor 32, and a capacitor 34 provided between the cathode.The capacitor 34 becomes conductive when the potential of the cathode of the first thyristor 16 rises when charging of the lead-acid battery 18 is completed, and the capacitor 34 is charged. As a result, the gate of the second thyristor 32 is energized.

This second thyristor 32 is provided between the gate circuit of the first thyristor 16 and the negative electrode side of the power supply 11, and is turned on when the gate is energized by the output of the charge end detection circuit 29. .

35 is a smoothing capacitor, and this smoothing capacitor 35 smoothes the current supplied to the second thyristor 32, the display circuit 25, etc.

FIG. 2 shows the on/off state of the light emitting element 28, for example, a light emitting diode (LED), the change in battery voltage, and the change in charging current in FIG. 1 in relation to each other.

Next, the operation of this embodiment will be explained with reference to FIG.

The charging power source 11 generates pulsating output on its positive and negative circuits, but on the cathode side of the diode 20, it is smoothed by the capacitor 35 and becomes a DC power source.

Now, if the voltage of the lead-acid battery 18 has decreased to the point where charging is required, the second thyristor 32 is in the off state in this case, so the gate potential of the first thyristor 16 becomes higher than the cathode potential. Therefore, the first thyristor 16 is turned on, and the pulsating output generated from the power source 11 is supplied to the lead-acid battery 18 via the diode 17 to charge it. At this time, a sufficiently high voltage is generated at the midpoint between the resistors 21 and 22 leading to the gate of the first thyristor 16, so the light emitting element 28 lights up to indicate that charging is in progress.

When the above-mentioned charging is completed, the voltage of the lead-acid battery 18 rises rapidly, and the potential on the cathode side of the first thyristor 16 also rises rapidly. Therefore, the charging end detection circuit 29 detects the voltage rise on the cathode side of the first thyristor 16 and turns on the second thyristor 32. Therefore, the potential of the first thyristor 16 through which the pulsating current flows decreases and becomes lower than the cathode potential, so that the first thyristor 16 does not turn on but remains in the off state and finishes charging. In addition, at this time, the potential at the midpoint between the voltage dividing resistors 21 and 22 also decreases and becomes lower than the Zener voltage of the Zener diode 26, so the Zener diode 26 enters a reverse blocking state, the light emission blocking 28 turns off, and the charging display ends. do.

Here, since the above circuit uses only the first and second thyristors 16 and 32 as three-terminal switching elements, the circuit is simpler than the one using three three-terminal switching elements shown in FIG. and lower prices. Furthermore, since the on-voltage of the light-emitting element 28 has almost no effect on the gate voltage of the first thyristor 16, the trouble of selecting an on-voltage that is suitable for the battery voltage as in the circuit shown in FIG. 4 is eliminated. , It has become possible to reduce costs from this aspect as well.

[Effects of the invention] According to the invention, the circuit can be simplified by reducing the number of switching elements, and the first thyristor for controlling the charging current can be replaced with the on-voltage of the light emitting element for displaying the charging state, unlike the conventional one. It is not affected and can be turned off reliably, and the light emitting element can also be turned off reliably. Therefore, there is no need to choose a light-emitting element with an on-voltage that is compatible with the voltage of the battery being discharged, and the manufacturing process becomes easy and costs are reduced. Furthermore, by providing the constant voltage element in the display circuit, the light emitting element is prevented from being turned on due to a voltage drop in the second thyristor during non-charging when the second thyristor is on.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a charging device showing an embodiment of the present invention, Fig. 2 is a time chart explaining the operation of each part in the circuit of Fig. 1, and Figs. 3 and 4 are different conventional charging devices. FIG. 2 is a circuit diagram showing the device. DESCRIPTION OF SYMBOLS 11... Power source for charging, 16... First thyristor, 18... Lead-acid battery as a battery to be charged, 2
1, 22...Voltage dividing resistor, 25...Display circuit, 26
...Zener diode as a constant voltage element, 2
8...Light emitting element, 29...Charging completion detection circuit, 3
2...Second thyristor.

Claims (1)

[Claims for Utility Model Registration] A charging power source for charging a battery to be charged, and a first battery having an anode connected to the positive side of the power source and a cathode connected to the negative side of the power source via the battery to be charged. One end is connected to the midpoint of the thyristor and a voltage dividing resistor provided between the anode side and the gate of this first thyristor, and the other end is connected to the negative electrode side of the power supply, and the potential at the midpoint is the set value. A display circuit having a constant voltage element that produces an output when the voltage exceeds the level, and a light emitting element that emits light based on the output of the constant voltage element; a charge completion detection circuit that generates a charge detection circuit; and a charge completion detection circuit that is provided between the gate side of the first thyristor and the negative electrode side of the power supply, and whose gate is connected to the output side of the charge detection circuit, and is turned on by the output of the charge detection circuit. A charging device comprising: a second thyristor.