JPS6159048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charging device for charging a storage battery such as a Ni--Cd battery used in electronic equipment, etc., and particularly to a charging device that can minimize the power supply voltage of the charging device to the necessary minimum.

Generally, when a Ni-Cd battery is charged with a constant current, the voltage between the terminals of this storage battery is approximately as shown in Figure 1.
It gradually increases slightly until the 80% charging point T ₁ , and from this approximately 80% charging point T ₁ until approximately 100% charging point T ₂ , the slope increases relatively steeply, and from this approximately 100% charging point T 1 It is known that the voltage between the terminals decreases after time _T2 . In particular, the phenomenon shown in Figure 1 is 1/2C (here, if the discharge capacity of a storage battery (100% charged) is, for example, 1 hour with a current of 4A flowing through it, then charging this storage battery with a current of 4A) This is noticeable when charging with a current higher than 1C.

A multiple charging device as shown in FIG. 2 is a system that effectively utilizes the phenomenon shown in FIG. is proposed.

In Fig. 2, 1 indicates a commercial power input terminal to which commercial power is supplied, and this commercial power input terminal 1
The commercial power supplied to the
are supplied to fixed contacts 3b, 3c, 3d and 3e, respectively. The movable contacts 3 of each of the first, second, third and fourth switches 3, 4, 5 and 6 of this switching device 2
A, 4a, 5a, and 6a are controlled by a switching control device 7 so that each time a control signal is supplied to the switching control device 7, they are sequentially linked and switched one stage at a time. Further, the commercial power obtained from the movable contact 3a of the first switching device 3 is supplied to a constant current circuit 9 via a rectifier circuit 8, and a current of about 2/3C, for example, is supplied to the output side of the constant current circuit 9. The constant current obtained at the output side of the constant current circuit 9 is connected to the movable contact 4 of the second switching device 4 of the switching device 2 so that a constant current of 3A is obtained.
supply to a. The first, second, third and fourth fixed contacts 4b, 4c, 4d and 4e of this second switch 4 are connected to the first, second, third and fourth charging terminals 10a, 10b, 10c, respectively. and 10d, respectively, and the constant current obtained at the output side of the constant current circuit 9 is used to charge a storage battery such as a Ni-Cd battery. Reference numeral 11 denotes a sampling pulse generator which generates one pulse every 2 to 10 minutes, for example, which is constructed using an astable multivibrator. The pulse interval generated by the sampling pulse generator 11 is set to a time period during which a change in the voltage between the charging terminals can be detected during charging of the Ni--Cd battery. The sampling pulse obtained at the output side of this sampling pulse generator 11 is supplied to one input terminal of each of AND circuits 12 and 13, and the sampling pulse obtained at the output side of this AND circuit 12 is applied to the sampling hold circuit 14. Supplied to pulse input terminal. Also, the first, second, and third switches of the second switch 4
and the fourth fixed contacts 4b, 4c, 4d and 4e are connected to the first, second, third and fourth contacts of the third switching device 5, respectively.
are connected to fixed contacts 5b, 5c, 5d, and 5e, respectively, and the terminal voltage of the Ni-Cd battery being charged, which is obtained at the movable contact 5a of this third switching device 5, is supplied to this sampling hold circuit 14 and compared. It is supplied to one input terminal of the circuit 15. This sampling hold circuit 14 is designed to hold the terminal voltage of the Ni--Cd battery at that time every time a sampling pulse is present at the sampling pulse input terminal. The output signal of the sampling and holding circuit 14 is supplied to the other input terminal of the comparison circuit 15. This comparison circuit 15 compares the output signal of the hold circuit 14 with the terminal voltage of the Ni-Cd battery, and this terminal voltage is determined by the output signal of the hold circuit 14.
When the voltage is higher than the voltage of the output signal of the hold circuit 14, a high signal H, for example, a positive voltage is obtained on the output side, and when this terminal voltage is lower than the voltage of the output signal of the hold circuit 14, a low signal L, for example a negative voltage, is obtained on the output side. This is done to obtain voltage. The signal obtained at the output side of this comparison circuit 15 is supplied to the other input terminal of the AND circuit 12, and the output signal of this comparison circuit 15 is passed through the inverter circuit 16 to the AND circuit 13.
to the other input terminal. This AND circuit 1
The output signal of No. 3 is supplied to the switching control device 7 via the OR circuit 17 as a control signal.

Also, in this example, charging terminals 10a, 10b, 1
The positive side ends a of 0c and 10d are grounded through a series circuit of a resistor 18a with a relatively large resistance value, e.g. 10KΩ, and a resistor 18b with a relatively small resistance value, e.g. 1KΩ, and the connection point of the resistors 18a and 18b is connected to the ground. A contact b is provided between the positive side end a and the positive side end a, and this contact b is electrically separated from the positive side end a when the Ni-Cd battery charging plug 20 is inserted, and when it is not inserted. is electrically connected to this positive side end a, that is, the resistor 18a is short-circuited. That is, the voltage obtained at the connection point of these resistors 18a and 18b is the same as that of the Ni-Cd battery charging plug 20.
When the charging plug 20 is plugged in, a relatively low voltage Va is divided by the resistors 18a and 18b, and when the charging plug 20 is not plugged in, the voltage obtained at the positive end a of the charging terminal is obtained as is. Therefore, a relatively high voltage Vb can be obtained. In this example, the first, second and fourth charging terminals 10
Three Ni− to be charged to a, 10b and 10d
It is assumed that the charging plugs 20 for the CD batteries 19a, 19b, and 19d are inserted. Also charging terminal 10
In each of a, 10b, 10c and 10d,
c is a grounding end.

These charging terminals 10a, 10b, 10c and 10
The connection points of the resistors 18a and 18b of d are respectively connected to the first, second, third and fourth fixed contacts 6b, 6c, 6d and 6e of the fourth switching device 6, and the fourth The movable contact 6a of the switch 6 is connected to the input side of the level detection circuit 21, and the level detection circuit 2
A control signal is obtained on the output side of 1 when the voltage supplied to this input side reaches a relatively high voltage Vb, and the control signal obtained on the output side of this level detection circuit 21 is switched via an OR circuit 17. Supplied to device 7. 7a is a power supply terminal to which DC voltage is supplied, and the first, second, third and fourth switching devices 3,
Fifth fixed contacts 3f, 4, 4, 5 and 6, respectively
f, 5f and 6f are electrically floating.

Next, to explain the operation of FIG. 2, Ni-Cd batteries 19a, 19b and 1
It is assumed that each charging plug 20 of 9d is inserted, and the first, second, and third charging plugs of the switching device 2 are initially connected.
The movable contacts 3a, 4a, 5a and 6a of the fourth switching devices 3, 4, 5 and 6 are connected to the first fixed contacts 3b, 4b, 5b and 6b, respectively. At this time, the commercial power from the commercial power input terminal 1 is rectified by the rectifier circuit 8 and supplied to the constant current circuit 9, and the current from this constant current circuit 9 is supplied to the charging terminal 10a, and connected to the charging terminal 10a. The charged Ni-Cd battery 19a is charged. In this case, since the charging plug 20 is inserted into the charging terminal 10a, the contact b is separated from the positive end a, and the resistors 18a and 18b
The voltage at the connection point becomes a relatively low voltage Va, and no control signal is obtained at the output side of the level detection circuit 21. At this time, it is assumed that a sampling pulse signal as shown in FIG. 3A is obtained on the output side of the sampling pulse generator 11, in which one pulse 11a exists every five minutes, for example. At the start of charging, Ni-Cd battery 1
Since the terminal voltage of terminal 9a is increasing as shown by curve S in FIG. 3B, sampling and holding circuit 14
At this time, the output side of the comparator circuit 15 receives a high signal H as shown in FIG. 3C.
Therefore, the AND circuit 12 becomes conductive, and a sampling pulse signal 12a as shown in FIG. 3D is obtained on the output side of the AND circuit 12.
The sampling pulse signal 12 obtained on the output side of
a is supplied to the sampling hold circuit 14, and depending on this sampling pulse, the Ni-Cd battery 19a is
The terminal voltages of the sampling and holding circuit 14 are sequentially sampled, and a stepped voltage as shown by the curve 14a in FIG. 3B is obtained at the output side of the sampling and holding circuit 14. this
While the voltage between the terminals of the Ni--Cd battery 19a is increasing, that is, until approximately 100% charging time _T2 , the above-described operations are performed sequentially. At this time, the output side of the inverter circuit 16, ie, the other input terminal of the AND circuit 13, is the low signal L, so the AND circuit 13 is non-conductive. Next, after this Ni-Cd battery 19a is charged to 100%, the terminal voltage S of this Ni-Cd battery 19a is
is the output voltage 14 of the sampling hold circuit 14
a, the output side of the comparison circuit 15 becomes a low signal L, the other input terminal of the AND circuit 12 becomes a low signal L, this AND circuit 12 becomes non-conductive, and the sampling and holding circuit 14 is supplied with a sampling pulse. The previous state is maintained. Also, at this time, the output side of the inverter circuit 16, that is, the other input terminal of the AND circuit 13, receives a high signal H.
Then, this AND circuit 13 becomes conductive, and a control signal 13a as shown in FIG. , the movable contacts 3a, 4a, 5a and 6a of the third and fourth switching devices 3, 4, 5 and 6 are connected to the second fixed contacts 3c, 4c, 5c and 6c, respectively, and the Ni-Cd battery 19a, and the second charging terminal 10b
The current from the constant current circuit 9 is supplied to the next Ni−
Charging of the CD battery 19b is started.

In this case, using the terminal voltage characteristics of the battery during charging as shown in Figure 1, the sampled terminal voltage and the terminal voltage of this battery are compared and approximately
This is approximately 100% because it detects when it is 100% charged.
You can reliably know when to charge. Therefore, it is possible to quickly charge the storage battery to 100% charge, reducing charging time. For example, I was able to charge it with a current of 2/3C and finish charging it in about 2 hours. Furthermore, as the charging current is further increased, the peak of the terminal voltage characteristic during charging as shown in FIG. is easy to obtain, and if the pulse interval of the sampling pulse generator 11 is made small, rapid charging becomes possible more quickly.

Also, in this case, as mentioned above, since the terminal voltage characteristics of the storage battery are used during charging, the voltage is always maintained at approximately 100% regardless of variations in the battery itself, temperature changes, etc.
There is a profit that can be charged by %.

Further, this Ni-Cd battery 19b is charged in the same manner as described above, and when the charging of this Ni-Cd battery 19b is completed, a control signal 13a as shown in FIG. 3E is obtained on the output side of the AND circuit 13, and this control signal 13a Accordingly, the switching control device 7 is operated, and the movable contacts 3 of each of the first, second, third and fourth switching devices 3, 4, 5 and 6 are operated.
a, 4, 5a and 6a respectively as third fixed contacts 3
Connect to d, 4d, 5d and 6d. In this case, since the charging plug 20 is not inserted into the third charging terminal 10c, the resistors 18a and 18b
The voltage at the connection point becomes a relatively high voltage Vb, and a control signal is obtained at the output side of the level detection circuit 21, and this control signal is supplied to the switching control device 7.
This switching control device 7 operates, and the first, second and third
The movable contacts 3a, 4a, 5a and 6a of the fourth switching devices 3, 4, 5 and 6 are respectively connected to the fourth fixed contacts 3e, 4e, 5e and 6e, and the fourth charging terminal 10d is connected to the fourth fixed contacts 3e, 4e, 5e and 6e. A current is supplied from the constant current circuit 9 to start charging the next Ni-Cd battery 19d. This Ni-Cd battery 19d is also charged in the same manner as the Ni-Cd battery 19a described above. When charging of the Ni--Cd battery 19d is completed, a control signal 13a as shown in FIG. The movable contacts 3a, 4a, 5a and 6a of the second, third and fourth switching devices 3, 4, 5 and 6 are connected to the fifth fixed contacts 3f, 4f, 5f and 6f, respectively. In this case, the fifth fixed contacts 3f, 4
Since f, 5f and 6f are each in an electrically floating state, the commercial power from the commercial power input terminal 1 is turned off.

As mentioned above, according to Fig. 2, multiple Ni−
Storage batteries 19a, 19b, 19c such as CD batteries are 1
Can be charged sequentially with multiple charging devices. Also, according to FIG. 2, a plurality of charging terminals 10a, 10b,
Even if there is a charging terminal in 10c or 10d to which a storage battery to be charged is not connected, current will be supplied to the next charging terminal by skipping over that charging terminal, so there will be no inconvenience even if there is a charging terminal to which a storage battery is not connected. There is no profit. Also, according to Figure 2, since the storage batteries to be charged are charged one by one, the charging current can be increased and the charging time for each can be reduced, compared to the case where multiple storage batteries are charged in parallel. As a result, the charging time for multiple storage batteries can be shortened.

However, in general, for storage batteries such as Ni-Cd batteries, the charging voltage when charged at a lower temperature (e.g. 0°C) than in a fully discharged state is higher than the charging voltage when charged at room temperature (e.g. 20°C). A battery cell whose charging voltage is 1.5V will have a charging voltage of 1.6V at 0°C. Also, when the temperature is low, for example 0
When a battery that has been charged once at ℃ is re-charged without discharging, as shown in Figure 4, the maximum charging voltage increases as the number of times it is charged increases, compared to the first time it is charged. I'll go. This tendency is particularly noticeable when the charging current is 1/2C or more during rapid charging. In FIG. 4, the symbols between each number of times are pause times. Here, H indicates the time and day indicates the day.

Therefore, if a battery that has been charged once is mistakenly charged a second time, a third time, etc. using a charging device as shown in FIG. 2, the battery can be charged again. Moreover, when the output voltage of the constant current circuit 9 is lower than this maximum charging voltage, the battery cannot be charged, so there is a problem that charging is not completed. In order to eliminate this inconvenience, the output voltage of this constant current circuit 9 must be made higher than necessary, and at this time, if the charging current from the constant current circuit 9 is greater than the current required for charging, this current The difference had to be absorbed by the constant current circuit 9, which caused the inconvenience that the constant current circuit 9 generated heat.

In view of this point, the present invention is designed to prevent recharging of a charged battery and to improve the above-mentioned disadvantages. An embodiment of the charging device of the present invention will be described below with reference to FIG. In FIG. 5, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and their explanation will be omitted.

In this example, the sampling hold circuit 14
A charging Ni-Cd battery 1 obtained on the output side of
The terminal voltage of 9a is supplied to the voltage detection circuit 22.
This voltage detection circuit 22 detects that the voltage of the storage battery to be charged has reached a predetermined value, for example, 0.1V higher than the maximum charging voltage when the first charge was performed at a low temperature, for example, 0°C, and sends a control signal to its output side. It was designed so that it could be obtained. 22a is a reference voltage setting device. Depending on the control signal obtained at the output side of the voltage detection circuit 22, a low signal L is sent to the output side of the comparison circuit 15.
The comparison circuit 15 is controlled so as to obtain . The rest of the structure is the same as in FIG. 2.

Since the present invention is configured as described above, when a storage battery that has been charged once is accidentally recharged, the terminal voltage is changed to the first charging voltage, e.g.
When a predetermined voltage, for example 17.7V, is higher than 17.6V by 0.1V, a control signal is obtained at the output side of the voltage detection circuit 22, which causes the output side of the comparator circuit 15 to become a low signal L, and the output side of the inverter circuit 16. That is, the other input terminal of the AND circuit 13 becomes a high signal H, this AND circuit 13 becomes conductive, and a control signal 13a as shown in FIG. 3E is obtained at the output side of this AND circuit 13. Accordingly, the switching control device 7 is operated to start charging the next storage battery. Other operations are the same as in FIG.

As described above, according to the present invention, when a storage battery that has been charged once is accidentally charged again, a predetermined value, e.g.
Since charging ends when the voltage increases by 0.1V, charging will not end even if the output voltage of the constant current circuit 9 is set to the minimum necessary level, for example, a predetermined value higher than the highest charging voltage during the first charging at low temperature. There are no inconveniences, and since the output voltage of the constant current circuit 9 can be minimized, there is an advantage that the charging current from the constant current circuit 9 does not become larger than the necessary current, and heat generation can be reduced.

In the above embodiment, the peak voltage is determined by comparing the memorized voltage with the current voltage, but it is of course possible to detect this peak voltage using a differentiating circuit. . Furthermore, in the above example, it was detected based on the stored voltage whether the terminal voltage reached a predetermined value higher than the highest charging voltage during the first charging at low temperature. Of course, it is also possible to detect whether the voltage has reached a predetermined value higher than the maximum charging voltage during charging.

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

[Brief explanation of the drawing]

1, 3, and 4 are diagrams for explaining the present invention, FIG. 2 is a configuration diagram showing an example of a charging device, and FIG. 5 is a configuration diagram showing an embodiment of the charging device of the present invention. It is a diagram. 1 is a commercial power supply input terminal, 2 is a 4-stage 5-stage switching device, 7 is a switching control device, 8 is a rectifier circuit, 9 is a constant current circuit, 10a, 10b, 10c and 10d are charging terminals, 11 is a sampling pulse generator 12 and 13 are AND circuits, 14 is a sampling hold circuit, 15 is a comparison circuit, 19
a, 19b and 19d are Ni-Cd batteries, 21
2 is a level detection circuit, and 22 is a voltage detection circuit.

Claims (1)

[Claims] 1. Compare the output of a circuit that samples and holds the terminal voltage of the Ni-Cd battery at predetermined time intervals with the above terminal voltage during charging, and determine the charging peak when the above terminal voltage becomes smaller than the sampled and held voltage. In a charging device that detects voltage and stops charging, the above conditions are met at the lowest operating temperature.
An erroneous charge detection circuit is provided that detects a voltage that is a predetermined value higher than the charging peak voltage when the Ni-Cd battery is 100% charged. A charging device characterized in that charging is stopped to prevent malfunctions during recharging.