JP3505747B2 - Charging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device having a constant current charging control circuit and a constant voltage charging control circuit capable of charging a plurality of secondary batteries.

[0002]

2. Description of the Related Art As a charging device for charging a plurality of secondary batteries, there is a difference in the charging capacities of the secondary batteries to be charged (differences in the voltage of the secondary batteries). As shown in FIG. 8, a series charging type charging device has been proposed which sequentially charges a plurality of secondary batteries.

Referring to FIG. 8, reference numeral 1 in FIG. 8 denotes a power supply circuit which supplies commercial power from a plug 2 to a rectifying circuit 4 via an input filter 3 for removing noise. The DC signal obtained at the output side of the rectifier circuit 4 is supplied to one end of the primary winding 5a of the conversion transformer 5.

The other end of the primary winding 5a of the conversion transformer 5 is connected to the collector of an npn transistor 6 for switching, the emitter of the transistor 6 is grounded, and the pulse width modulation control circuit is provided at the base of the transistor 6. A pulse width modulation signal from the power supply circuit 7 is supplied to control the ON period of the transistor 6 and the voltage and current of the output signal of the power supply circuit 1.

One end of the secondary winding 5b of the conversion transformer 5 is connected to the other end of the secondary winding 5b through a series circuit of a rectifying diode 8 and a smoothing capacitor 9, and this secondary winding 5b is connected. The other end of the wire 5b is grounded.

The connecting point of the diode 8 and the capacitor 9 forming the rectifying circuit is connected to the movable contact 1 of the changeover switch 10.
0a, and one fixed contact 10 ₁ of this changeover switch 10 is grounded via a series circuit of a first secondary battery 11a to be charged and resistors 12a and 13 for current detection, and this changeover is also made. The other fixed contact 10 ₂ of the switch 10
Rechargeable secondary battery 11b, current detecting resistor 12
It is grounded through the series circuit of b and 13.

The diode 8 which constitutes this rectifying circuit
And the connection point of the capacitor 9 to the resistor 1 for detecting the output voltage
This resistor 14 is grounded through a series circuit of 4 and 15.
And the middle point of connection of 15 are connected to the inverting terminal (− terminal) of the operational amplifier circuit 16 which constitutes the constant voltage charging control circuit, and the non-inverting terminal (+ terminal) of this operational amplifier circuit 16 is the output of this power supply circuit 1. The side is grounded via a battery 17 which obtains a reference voltage for obtaining a constant voltage Vo, for example, 8V.

The connection point of the resistors 12a, 12b and 13 is connected to the inverting terminal (-terminal) of the operational amplifier circuit 18 constituting the constant current charge control circuit, and the non-inverting terminal (+ terminal) of the operational amplifier circuit 18 is connected. ) Is grounded to the output side of the power supply circuit 1 via a battery 19 which obtains a constant current I, for example, a reference voltage for obtaining a constant current of 1A.

The output side of the rectifying circuit, that is, the ground point of the diode 8 and the capacitor 9 is connected to the anode of the light emitting diode 20a constituting the photocoupler 20, and the cathode of the light emitting diode 20a is connected to the backflow preventing diode 2.
1 and 22 are connected to the output terminals of the operational amplifier circuits 16 and 18, respectively.

A signal corresponding to the impedance change of the phototransistor 20b constituting the photocoupler 20 is supplied to the pulse width modulation control circuit 7, and the pulse width modulation control circuit 7 produces a pulse corresponding to the impedance of the phototransistor 20b. A pulse width modulated signal of the width is obtained.

Further, the inverting terminal (-terminal) of the operational amplifier circuit 23 constituting a current detection circuit for detecting the current at the time when the charging of the secondary battery is completed at the connection midpoint of the secondary battery 11a and the resistor 12a. And the non-inverting terminal (+ terminal) of the operational amplifier circuit 23 is grounded via the battery 24 that can obtain the reference voltage corresponding to the charge termination current of the secondary battery. In the operational amplifier circuit 23, the high level signal "1" is sent to the charge control circuit 25 when the charging of the secondary battery 11a is completed.
To supply.

Further, the inverting terminal (-terminal) of the operational amplifier circuit 26 constituting a current detection circuit for detecting the current when the charging of the secondary battery is completed at the midpoint of connection between the secondary battery 11b and the resistor 12b. And the non-inverting terminal (+ terminal) of the operational amplifier circuit 26 is grounded via the battery 27 that can obtain the reference voltage corresponding to the charging end current of the secondary battery. Also in the operational amplifier circuit 26, the high level signal "1" is supplied to the charge control circuit 25 when the charging of the secondary battery 11b is completed.

The charge control circuit 25 is used for the secondary battery 1
The light emitting diode 28 provided in the display unit 28 while charging 1a
The display unit 2 is turned on while a is turned on and the secondary battery 11b is being charged.
The light emitting diode 28b provided in FIG. 8 is turned on, and after the secondary batteries 11a and 11b are charged, the light emitting diodes 28a and 28b are turned off. The charge control circuit 25 controls switching of the movable contact 10a of the changeover switch 10. At the start of charging, the movable contact 10a is connected to _one fixed contact 10 ₁ to connect the secondary battery 11a. After charging and charging the secondary battery 11a,
This movable contact 10a is connected to the other fixed contact 10 ₂ ,
The secondary battery 11b is charged.

In the charging device as shown in FIG.
When charging the secondary battery 11a or 11b, as shown in FIG.
As shown in B and C, the secondary battery 11a or 11 is initially charged.
Since a relatively large current flows through b, the output side of the operational amplifier circuit 18 which constitutes the constant current charge control circuit becomes the low level signal "0", and the constant current charge control is performed. At this time, the voltage across the secondary battery 11a or 11b is lower than the rated voltage of the secondary battery 11a or 11b, as shown in FIG. 9A, and the output side of the operational amplifier circuit 16 that constitutes the constant voltage charging control circuit is at a high level signal. It is "1", and the constant voltage charging control circuit is inoperative.

Next, when the voltage across the secondary battery 11a or 11b reaches the rated voltage, the output side of the operational amplifier circuit 16 constituting the constant voltage charging control circuit becomes the low level signal "0", and the constant voltage charging is performed. Under control, the current flowing through the secondary battery 11a or 11b droops and becomes smaller than the value determined by the battery 19, so that the output side of the operational amplifier circuit 18 constituting this constant current charging control circuit outputs a high level signal "1". ", And this constant current charge control circuit becomes inoperative.

Next, when the current flowing through the secondary battery 11a or 11b becomes lower than the value determined by the battery 24 or 27, the charging is terminated.

[0017]

However, such a charging device as shown in FIG. 8 is such that when one secondary battery 11a is charged, another secondary battery 11b is switched to charging and the conventional charging device is used. In the charging device, the charging time is determined by the number of secondary batteries to be charged. For example, if the charging time of one secondary battery is 2 hours, the charging time of 2 batteries will be 4 hours. there were.

In view of the above point, the present invention has an object of enabling a plurality of secondary batteries to be favorably charged in parallel and shortening the charging time.

[0019]

The charging device of the present invention, for example, as shown in FIG.
The direct current signal obtained at the output side of the rectifier circuit 4 is turned on / off by the pulse width modulation signal from the pulse width modulation control circuit 7, and the switching element 6 is supplied to the primary winding 5a of the conversion transformer 5. Secondary winding 5b of conversion transformer 5
Of the secondary batteries 11a, 11b to be charged by rectifying the voltage of
To each of the plurality of secondary batteries 11a and 11b, and resistors 12a and 12b inserted in series in the respective current paths of the plurality of secondary batteries 11a and 11b.
The constant current charging control circuit 18 for controlling the pulse width modulation control circuit 7 by comparing the value obtained by adding the voltage between terminals of a and 12b with the reference value, and the terminal voltage of the plurality of secondary batteries 11a, 11b. A constant voltage charge control circuit 1 for controlling the pulse width modulation control circuit 7 by comparing the reference value with a voltage comparator.
6 and a constant current / constant voltage charge determination circuit 30 for detecting the operation of the constant current / charge control circuit 18 and the operation of the constant voltage / charge control circuit 16. The end of charging of the plurality of secondary batteries 11a and 11b is determined.

[0020]

According to the present invention, the constant current / constant voltage charging determination circuit 30 is provided.
Therefore, when it is determined that the state of charge of the plurality of secondary batteries is constant current charging, the output of the constant current / constant voltage charging determination circuit 30 prohibits the determination of the end of charging by the current detection circuit. Therefore, it is possible to avoid erroneous detection of the end of charging when a plurality of secondary batteries are charged in parallel.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the charging device of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 8 are designated by the same reference numerals, and detailed description thereof will be omitted. In this example, a commercial power source from the plug 2 is supplied to the rectifier circuit 4 via an input filter 3 that removes noise that constitutes the power source circuit 1 for charging, and a DC signal obtained at the output side of the rectifier circuit 4 is supplied. Primary winding 5a of conversion transformer 3
Supply at one end of.

The other end of the primary winding 5a of the conversion transformer 5 is connected to the collector of an npn transistor 6 for switching, the emitter of the transistor 6 is grounded, and the base of the transistor 6 has a pulse width modulation control circuit. The pulse width modulation signal from the power supply circuit 7 is supplied to control the ON period (ON duty) of the transistor 6 to control the voltage and current of the output signal of the power supply circuit 1.

One end of the secondary winding 5b of the conversion transformer 5 is connected to the other end of the secondary winding 5b through a series circuit of a rectifying diode 8 and a smoothing capacitor 9, and this secondary winding 5b is connected. The other end of the wire 5b is grounded.

The connection points of the diode 8 and the capacitor 9 which form the rectifying circuit, which is the output terminal of the power supply circuit 1, are connected to the first and second secondary to be charged via the backflow preventing diodes 31a and 31b, respectively. The positive electrodes of the batteries 11a and 11b are respectively connected, and the negative electrodes of the secondary batteries 11a and 11b are grounded via the current detecting resistors 12a and 12b, respectively.

Further, the diode 8 constituting this rectifying circuit
And the connection point of the capacitor 9 to the resistor 1 for detecting the output voltage
This resistor 14 is grounded through a series circuit of 4 and 15.
And 15 are connected to the inverting terminal (− terminal) of the operational amplifier circuit 16 that constitutes the constant voltage charging control circuit, and the non-inverting terminal (+ terminal) of this operational amplifier circuit 16 is connected to the power supply circuit 1. The output side is grounded via a battery 17 that obtains a reference voltage for obtaining a constant voltage Vo, for example, 8V.

The connection point between the secondary battery 11a and the resistor 12a is connected via the resistor 32a to the inverting terminal (-terminal) of the operational amplifier circuit 18 constituting the constant current charge control circuit, and the secondary battery 11b is connected. The connection point of the resistor 12b and the resistor 12b is connected via the resistor 32b to the inverting terminal (-
Terminal).

In this case, the voltage corresponding to the combined current of the charging currents flowing in the secondary batteries 11a and 11b is supplied to the inverting terminal (-terminal) of the operational amplifier circuit 18. Further, in this case, if the resistance values of the resistors 32a and 32b are made larger than the resistance values of the resistors 12a and 12b, the current flowing through the resistors 32a and 32b can be ignored. At this time, the inverting terminal (-
Since the impedance of (terminal) is large, this resistor 32
Little current flows in a and 32b, and a small resistor having a small withstand power can be used.

The non-inverting terminal (+ terminal) of the operational amplifier circuit 18 is grounded to the output side of the power supply circuit 1 through a battery 19 which obtains a constant current I, for example, a reference voltage for obtaining a constant current of 1A.

The operational amplifier circuit 23, which constitutes a current detection circuit for detecting the current when the secondary battery 11a and the resistor 12a are connected to each other via the resistor 34a, when the charging of the secondary battery is completed. The operational amplifier circuit 23 is connected to the inverting terminal (− terminal), and the non-inverting terminal (+ terminal) of the operational amplifier circuit 23 is grounded via the battery 24 that can obtain the reference voltage corresponding to the charge termination current of the secondary battery.

Further, the operational amplifier circuit 26 constituting a current detection circuit for detecting the current when the secondary battery 11b and the resistor 12b are connected to each other via the resistor 34b at the midpoint of the connection between the secondary battery 11b and the resistor 12b. The operational amplifier circuit 26 is connected to the inverting terminal (− terminal), and the non-inverting terminal (+ terminal) of the operational amplifier circuit 26 is grounded via the battery 27 that obtains the reference voltage corresponding to the charge termination current of the secondary battery.

In this example, the output terminal of the operational amplifier circuit 16 which constitutes the constant voltage charge control circuit is connected to the inverting terminal (-terminal) of the operational amplifier circuit 30 which constitutes the constant current constant voltage charge discriminating circuit, and the constant current. The output terminal of the operational amplifier circuit 18 forming the charge control circuit is connected to the non-inverting terminal (+ terminal) of the operational amplifier circuit 30 forming the constant current / constant voltage charge determination circuit.

In this case, the output terminal of the operational amplifier circuit 30 which constitutes the constant current / constant voltage charge discrimination circuit is when the output terminal of the operational amplifier circuit 18 in which the constant current charge control circuit is operating is the low level signal "0". Is a low level signal “0”, and the operational amplifier circuit 1 in which the constant voltage charge control circuit is operating
When the output terminal of 6 is a low level signal "0", it becomes a high level signal "1".

Further, in this example, the operational amplifier circuit 3
The output terminal of 0 is connected to the other input terminal of each of the AND circuits 33a and 33b, and the output terminals of the operational amplifier circuits 23 and 26 for detecting the charging end current are connected to one of the AND circuits 33a and 33b, respectively. And the output signals of the AND circuits 33a and 33b are supplied to the charge control circuit 25.

According to this example, the AND circuits 33a and 33a
When the constant current charge control circuit is in operation by 3b, the judgment of the end of charging is not made.

In the charge control circuit 25, when the secondary batteries 11a and 11b start charging, the light emitting diodes 28a and 28b of the display unit 28 are turned on, and the output signals of the AND circuits 33a and 33b are at a high level. When the signal becomes "1", the light emitting diodes 28a and 28b are turned off and the charging is terminated.

The operation of the example of FIG. 1 will be described. First,
A case where charging of the secondary batteries 11a and 11b is started at the same time will be described with reference to FIG. In this case, since the backflow prevention diodes 31a and 31b are provided in FIG. 1, even if there is a difference in the battery voltage between the secondary batteries 11a and 11b, there is no inconvenience that the backflow current flows, and charging is performed. The current is shunted to the secondary batteries 11a and 11b and can be charged in parallel.

When the secondary batteries 11a and 11b are simultaneously charged in parallel, as shown in FIGS. 2A, 2B and 2C, a relatively large current flows through the secondary batteries 11a and 11b at the beginning of charging and a constant current charge control circuit is provided. Operational amplifier circuit 1
The secondary batteries 11a and 11b are connected to the inverting terminal (-terminal) of No. 8
A voltage corresponding to the combined current of the charging currents flowing to each of them is supplied, the output side of the operational amplifier circuit 18 becomes a low level signal "0", and constant current charging control is performed.

At this time, the voltage across the secondary batteries 11a and 11b is as shown in FIG. 2A.
Lower than a predetermined voltage Vo determined by the rated voltage of 1b,
The output side of the operational amplifier circuit 16 constituting the constant voltage charge control circuit is the high level signal "1", and the constant voltage charge control circuit is inoperative.

Next, when the voltage across the secondary batteries 11a and 11b reaches a predetermined voltage Vo, the output side of the operational amplifier circuit 16 constituting the constant voltage charging control circuit becomes a low level signal "0". , Controlled by constant voltage charging.

At this time, the currents flowing through the secondary batteries 11a and 11b droop as shown in FIGS. 2B and 2C, and the voltage determined by this combined current becomes smaller than the reference voltage of the battery 19. Operational amplifier circuit 1
The output side of 8 becomes a high level signal "1", and this constant current charging control circuit becomes inoperative.

Next, when the currents flowing through the secondary batteries 11a and 11b become lower than the values determined by the batteries 24 and 27, respectively, the constant voltage charging control circuit is already in operation and the output side of the operational amplifier circuit 30. Is a high level signal "1", the charging is terminated respectively.

According to the present example, the two secondary batteries 11
The time for constant current charging control to charge a and 11b was about 40 minutes, which is about twice as long as 20 minutes for charging one secondary battery, but the time for constant voltage charging control is Almost equal to the case of charging one secondary battery, for example, 1 hour 10
According to this example, there is an advantage that the charging time can be significantly shortened as compared with the case where two secondary batteries are sequentially charged.

Next, referring to the example of FIG. 1, when the charging of the secondary battery 11b is started while the secondary battery 11a is being charged (the same applies when the battery voltages of the two secondary batteries 11a and 11b are different). Will be described with reference to FIGS. 3A, 3B, 3C and 3D.

First, the secondary battery 11a is mounted on the charging device of FIG. 1, and as shown in FIGS. 3A and 3B, similarly to the conventional example, the constant current charge control is first performed, and then the constant voltage charge control is performed and the charging current droops. It is assumed that the charging of the secondary battery 11b is started when the charging is completed but the charging is not completed (after the lapse of the period I).

At this time, since the voltage of the secondary battery 11b is lower than the predetermined voltage Vo, the charging device is again in the constant current charging control state as shown in FIG. 3C, and the voltage on the output side of the power supply circuit 1 becomes The voltage drops to the voltage of the secondary battery 11b.

At this time, since the output voltage of the power supply circuit 1 is lower than the voltage of the secondary battery 11a (II period), the charging current is extremely reduced in the II period as shown in FIG. 3B. At this time, the output side of the operational amplifier circuit 30 which constitutes the constant current / constant voltage charge determination circuit has the low level signal "0" as shown in FIG.

Next, the charging of the secondary battery 11b proceeds and the current drops (III period), but the charging current also starts flowing to the secondary battery 11a. This is a state in which the battery voltage on the secondary battery 11b side is very close to the battery voltage on the secondary battery 11a.

At this time, the output side of the operational amplifier circuit 30 is still under constant current charge control when the combined current of the secondary batteries 11a and 11b is a predetermined constant current I, for example 1A, as shown by the chain line in FIG. 3B. .

When the charging current of the secondary battery 11a rises and then drops again (IV period), the output side of the operational amplifier circuit 30 switches from the low level signal "0" to the high level signal "1". At this time, as shown in FIGS. 3B and 3C, the combined charging current of the secondary batteries 11a and 11b is drooping, and thereafter, the charging end determination signals of the operational amplifier circuits 23 and 26 for detecting the charging end current are valid. Becomes

In this example, a plurality of secondary batteries are charged in parallel by distinguishing between constant current charging control and constant voltage charging control by the operational amplifier circuit 30 which constitutes the constant current / constant voltage determining circuit as described above. There is an advantage that it is possible to avoid the false detection of the end of charging that occurs.

Further, according to this example, the current detection for controlling the constant current charging of the charging device is performed by the plurality of secondary batteries 11a and 11b.
Of the charging current detection resistors 12a and 1 connected to the respective
2b is used to take out as a combined current of the charging currents of the plurality of secondary batteries 11a and 11b, so a large-sized resistor 13 having a large withstand power for current detection for constant current control, which has been conventionally required. There are benefits that do not require.

FIG. 4 shows another embodiment of the present invention.
4 will be described. In FIG. 4, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 4, the output side of the operational amplifier circuit 30 is provided without the AND circuits 33a and 33b of FIG. 1 via the diodes 35a and 35b for preventing backflow, respectively, and the operational amplifier circuit 23 for detecting the charging end current and 26 is connected to each inverting terminal (-terminal). Others are the same as those in FIG.

Also in FIG. 4, in the constant current charging control, the output side of the operational amplifier circuit 30 becomes a high level signal "1", which is supplied to the inverting terminals (-terminals) of the operational amplifier circuits 23 and 26. Therefore, at this time, the operational amplifier circuits 23 and 26 do not determine the end of charging. Therefore, it can be easily understood that the same effects as those in the example of FIG. 1 can be obtained in the example of FIG.

FIG. 5 shows another embodiment of the present invention. 5 will be described. In FIG. 5, parts corresponding to those in FIGS. 1 and 8 are designated by the same reference numerals, and detailed description thereof will be omitted. In the example of FIG. 5, the positive terminal of the power supply circuit 1 is connected to the movable contacts 36a and 37a of the connection switches 36 and 37, respectively.
The fixed contact 36b of the connection switch 36 is connected to the negative terminal of the power supply circuit 1 through the series circuit of the secondary battery 11a and the resistor 12a, and the fixed contact 37b of the connection switch 37 is connected to the secondary battery 11b. And a resistor 12b connected in series to the negative terminal of the power supply circuit 1.

Further, the connection point of the secondary battery 11a and the resistor 12a is connected to the inverting terminal (-terminal) of the operational amplifier circuit 23 for detecting the charging end current, and the connection point of the secondary battery 11b and the resistor 12b is charged. The reference voltage corresponding to the charging end current is obtained by connecting to the inverting terminal (− terminal) of the operational amplifier circuit 26 for detecting the termination current, and each non-inverting terminal (+ terminal) of the operational amplifier circuits 23 and 26. Grounded via battery 24.

In the operational amplifier circuits 23 and 26, the high level signal "1" is supplied to the charge control circuit 25 when the secondary batteries 11a and 11b have been charged, respectively.

In this example, the charge control circuit 25 is composed of a microcomputer, and the control operation is performed as shown in the flow chart of FIG. Others are the same as those in FIG.

The operation of the example of FIG. 5 will be described with reference to FIGS. 6 and 7. In FIG. 5, the secondary battery 11a
In order to describe the case of charging 11 and 11b, charging is started first. At this time, the charge control circuit 25 displays
The light emitting diodes 28a and 28b of No. 8 are turned on (step S1).

Next, the connection switch 36 is turned on as shown in FIG. 6D (step S2), and the secondary battery 11a is turned on as shown in FIG. 6A.
Constant current charging control as shown in B, and operational amplifier circuit (CP
This state is continued until the output side of the (M)) 30 becomes the high level signal "1" as shown in FIG. 6F (step S
3), when the output side of the operational amplifier circuit 30 becomes the high level signal “1”, the connection switch 36 is turned on as shown in FIG. 6D.
It is turned off as shown in (step S4).

Next, the connection switch 37 is turned on as shown in FIG. 6E (step S5), and the secondary battery 11b is turned on as shown in FIG.
Constant current charge control is performed as shown in A and C, and the operational amplifier circuit (C
This state is continued until the output side of the P (M)) 30 becomes the high level signal "1" as shown in FIG. 6F (step S
6) When the output side of the operational amplifier circuit 30 becomes the high level signal "1", the two connection switches 36 and 37 are turned on as shown in FIGS. 6D and 6E (step S7), and the secondary switch The batteries 11a and 11b are charged in parallel. In this case, constant voltage charging control is performed as shown in FIGS. 6A, 6B and 6C.

Next, it is judged whether the output side of the operational amplifier circuit (CP (A)) 23 for detecting the charging end current of the secondary battery 11a is the low level signal "0" (step S8) and the secondary battery It is determined whether or not the output side of the operational amplifier circuit (CP (B)) 26 for detecting the charging end current of 11b is the low level signal "0" (step S9). At this time, the constant current charging control is continued.

Next, when charging of the secondary batteries 11a and 11b is completed and the output sides of the operational amplifier circuits 23 and 26 become high level signals "1", the light emitting diode 2
8a and 28b are turned off respectively (steps S10 and S1).
1). When it is determined that both of the light emitting diodes 28a and 28b are turned off (step S12), the connection switches 36 and 37 are turned off and the charging is completed.

In this example as well, a plurality of secondary batteries 11a and 11b are charged in parallel during constant voltage charge control, so that the same effect as in FIG. 1 can be obtained in this FIG. 5 example as well. Of course.

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

[0065]

According to the present invention, there is an advantage that a plurality of secondary batteries can be favorably charged in parallel and the charging time can be shortened. Further, according to the present invention, a constant current / constant voltage charge determination circuit is provided, and when the state of charge for the plurality of secondary batteries is constant current charge, the determination of the end of charging is prohibited. There is a benefit of avoiding false detection of the end of charging when parallel charging is performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a charging device of the present invention.

FIG. 2 is a diagram used to explain FIG.

FIG. 3 is a diagram used for explaining FIG.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the present invention.

FIG. 6 is a diagram used to explain FIG.

FIG. 7 is a flowchart used to explain FIG.

FIG. 8 is a configuration diagram showing an example of a conventional charging device.

9 is a diagram used to explain FIG. 8. FIG.

[Explanation of symbols]

1 Power Supply Circuit 6 Switching Transistor 7 Pulse Width Modulation Control Circuits 11a, 11b Secondary Batteries 12a, 12b Resistor 16 Operational Amplifier Circuit 18 Constituting Constant Voltage Charging Control Circuit Operational Amplifier Circuit 20 Constituting Constant Current Charging Control Circuit Coupler 23, 26 Charging end current detection operational amplifier circuit 25 Charge control circuit 28 Display unit 30 Constant current constant voltage charge operational amplifier circuit 33a, 33b AND circuit 35a, 35b Diode forming a discrimination circuit

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J 7/02 H01M 10/44

Claims (3)

(57) [Claims] 1. An AC power supply is supplied to a rectification circuit, and a DC signal obtained at the output side of this rectification circuit is turned on / off by a pulse width modulation signal from a pulse width modulation control circuit to control the switching element to turn on / off. A power supply circuit that supplies the power to the primary winding and rectifies the voltage of the secondary winding of the conversion transformer to supply charging power to the plurality of secondary batteries to be charged, and each of the plurality of secondary batteries. A constant current charge control circuit for controlling the pulse width modulation control circuit by comparing a value obtained by adding a voltage between terminals of the resistor in series with the current path of the resistor and a reference value; A constant voltage charge control circuit for controlling the pulse width modulation control circuit by comparing the terminal voltage of the secondary battery with a reference value by a voltage comparator, and the operation of the constant current charge control circuit and the operation of the constant voltage charge control circuit. Constant current to detect And a 圧充 conductive discrimination circuit, the charging apparatus being characterized in that so as to determine the charge end of the plurality of secondary batteries by the output of the constant current constant voltage charging judgment circuit. 2. The constant current / constant voltage charge determination circuit compares a value obtained by adding voltages between terminals of resistors inserted in series in respective current paths of the plurality of secondary batteries with a reference value. A first voltage comparator, a second voltage comparator for comparing a combined terminal voltage of the plurality of secondary batteries with a reference voltage, an output of the first voltage comparator and a second voltage comparator. The charging device according to claim 1, comprising a third voltage comparator for comparing the output with the third voltage comparator. 3. The charging device according to claim 2, wherein the display of the end of charging of the plurality of secondary batteries is controlled by the output of the constant current / constant voltage charging determination circuit.