JP2002152983A - Charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the charging time of a charger for simultaneously charging a plurality of batteries, which require constant voltage control. SOLUTION: The charger comprises a first charging circuit, including a main transistor Q1 and a second charging circuit which includes a main transistor Q2 A charging voltage of each charging circuit is controlled to a constant voltage with an individual voltage monitoring means and a feedback circuit, including the main transistors and a charging current of each charging circuit is controlled to a constant current, with a current monitoring means for common sum of such charging currents and a plurality of feedback circuits including main transistors of the charging circuits. The voltage-monitoring means includes a circuit, comprising an operational amplifier IC3 in the first charging circuit, a circuit comprising an operational amplifier IC4 in the second charging circuit, while the common current monitoring mans comprises a resistor R1 for current detection and an operational amplifier IC1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for simultaneously charging a plurality of batteries requiring constant voltage control, for example, a plurality of lithium ion batteries.

[0002]

2. Description of the Related Art FIG. 2 is a circuit diagram of a conventional charger, in which a first charging circuit for charging a battery 10 connected between a pair of charging terminals 11 and 12 and a pair of charging terminals 21 and 22 are provided. And a two-output charging circuit having a second charging circuit for charging the battery 20 connected between them. The charging voltage of each charging circuit is controlled at a constant voltage, and the charging current is controlled at a constant current.

[0003] That is, the first charging circuit, and its emitter is connected to the charging terminal 11 via a current detection resistor R ₁ is its collector to charge the connected battery 10 between a pair of charging terminals 11 and 12 There the first transistor _{Q 1} which is connected to the power supply terminal 31 of the power source 30, the first transistor _{Q 1}
A first control circuit for controlling the first voltage comparison circuit that constantly detects the voltage V _1, to generate a voltage control command signal by comparing the detected voltage with the reference value between the charging terminals 11 and 12 If, and detects the charging current I ₁ at all times, the detected current is compared with a reference value and a first current comparator circuit for generating a command signal for current control.

[0004] The first control circuit includes a first output terminal for applying an operational amplifier IC ₅ which is connected to the base of the transistor Q ₁ via a resistor R _25, a reference voltage V _ref1 to the inverting input terminal of the operational amplifier IC ₅ And a reference voltage circuit for transistor control. The first transistor control reference voltage circuit includes a resistor voltage dividing circuit including a resistor R ₁₇ and a resistor R ₁₉ connected between the common side power supply terminal 32 of the power supply 30 and the reference voltage terminal 33.

The first voltage comparison circuit has an output terminal connected to a resistor.
R_{twenty three}And diode D₃Operational amplifier IC through a series circuit
₅Operational amplifier IC connected to the non-inverting input terminal₃When,
This operational amplifier IC₃Reference voltage V_ref2
A first voltage control reference voltage circuit for applying
The voltage of the charging terminal 11 of the road to the operational amplifier IC₃Non-anti
Resistor R transmitted to the input terminal₁₅Consists of This first voltage
The control reference voltage circuit is a common side power supply terminal 32 of the power supply 30.
And a resistor R connected between the ₁₁And resistance
R₁₃And a resistor voltage dividing circuit.

[0006] The first current comparator circuit, the collector of the transistor Q ₁ and the current detection resistor R ₁ which is inserted between the charging terminal 11, the output terminal resistor R ₂₁ and diode D ₁
An operational amplifier IC ₁ which is connected to the non-inverting input terminal of the operational amplifier IC ₅ via a series circuit of a resistor R ₉ to convey the reference voltage V _ref to the inverting input terminal of the operational amplifier IC _1, also the inverting input of the operational amplifier IC ₁ a resistor R ₇ connected between one end of the terminal and the current detection resistor R _1, by applying a voltage between the other end and the common line of the current detection resistor R ₁ minute non-inverting input of the operational amplifier IC ₁ It is composed of a resistor R ₃ to give the terminal a resistor divider resistor R _5.

[0007] The second charging circuit for charging the battery connected 20 between the pair of output terminals 21 and 22, and its emitter is connected to the charging terminal 21 via a collector current detection resistor R ₂ There a second transistor _{Q 2} to which is connected to the power supply terminal 31 of the power supply 30, the second transistor _{Q 2}
A second control circuit for controlling the second voltage comparison circuit that constantly detects the voltage V _2, to generate a voltage control command signal by comparing the detected voltage with the reference value between the charging terminal 21 and 22 If, and detects the charging current I ₂ at all times, the detected current is compared with a reference value and a second current comparator circuit for generating a command signal for current control.

[0008] The second control circuit includes an operational amplifier IC ₆ connected to the base of the transistor Q ₂ through the output terminal of the resistor R _26, the second to apply a reference voltage V _ref1 to the inverting input terminal of the operational amplifier IC ₆ And a reference voltage circuit for transistor control. The reference voltage circuit for controlling the second transistor comprises a resistor voltage dividing circuit of a resistor R ₁₈ and a resistor R ₂₀ connected between the common side power supply terminal 32 of the power supply 30 and the reference voltage terminal 33.

The output terminal of the second voltage comparison circuit is a resistor.
R_{twenty four}And diode D₄Operational amplifier IC through a series circuit
₆Operational amplifier IC connected to the non-inverting input terminal₄When,
This operational amplifier IC₄Reference voltage V_ref2
A second voltage control reference voltage circuit for applying
The voltage of the charging terminal 21 of the road to the operational amplifier IC₄Non-anti
Resistor R transmitted to the input terminal₁₆Consists of This second voltage
The control reference voltage circuit is a common side power supply terminal 32 of the power supply 30.
And a resistor R connected between the ₁₂And resistance
R₁₄And a resistor voltage dividing circuit.

[0010] The second current comparator circuit, the transistor Q and the current detection resistor R ₂ that is inserted between the collector and the charging terminal 21 of _2, the output terminal resistor R ₂₂ and diode D ₂
An operational amplifier IC ₂ connected to the non-inverting input terminal of the operational amplifier IC ₆ via a series circuit of, the operational amplifier IC ₂
A resistor R ₁₀ to convey the reference voltage V _ref to the inverting input terminal of
Similarly voltage dividing between the resistors R _8, which are connected between one end of the inverting input terminal and the current detection resistor R ₂ of the operational amplifier IC _2, the other end and the common line of the current detection resistor R ₂ Resistor R _{4 applied} to the non-inverting input terminal of the operational amplifier IC ₂
And a and the resistor divider resistor R _6.

FIG. 4 is a characteristic curve diagram when the lithium ion batteries 10 and 20 are simultaneously charged by the conventional charger configured as described above. That is, FIG. 4A shows a charge characteristic curve of the fully-discharged lithium-ion battery 10, and FIG.
(B) is a charging characteristic curve of the lithium ion battery 20 of 50% discharge, the time t ₁ is the 50% discharge terminal voltage of the lithium ion battery 10 has reached the set voltage in the drawing,
t ₂ is the time when the terminal voltage of the lithium ion battery 20 of the full discharge has reached the set voltage. As is clear from FIG.
t ₂ is about 2 times of _{t 1.} This is because in the conventional charger, the first charging circuit and the second charging circuit independently perform constant current and constant voltage control. Therefore, the conventional charger in which each charging circuit is independently controlled at a constant current and a constant voltage has a problem that the charging time of the completely discharged lithium ion battery 10 cannot be shortened.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the charging time in a charger for simultaneously charging a plurality of batteries requiring constant voltage control.

[0013]

In order to solve the above-mentioned problems, in a charger for charging a plurality of batteries at the same time, a constant voltage is individually set so that a charging voltage between respective charging terminals is maintained at a constant voltage value. The control is performed, and the constant current control is performed such that the sum of the respective charging currents is maintained at a constant current value.

In order to solve the above-mentioned problem, in a charger comprising a plurality of charging circuits each having a main transistor, the charging voltage of each charging circuit is controlled by individual voltage monitoring means and a feedback circuit including the main transistor. The configuration is such that the constant voltage control is performed, and the constant current control of the sum of the charging currents of the charging circuits is performed by a plurality of feedback circuits including a common current monitoring unit and a main transistor of each charging circuit.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 which is a circuit diagram of one embodiment of the present invention, a first charging circuit for charging a battery 10 connected between a pair of charging terminals 11 and 12 has a collector. power supply terminal 31 of the plus side connected to the charging terminal 11 and the power source 30 through the emitter of the current detection resistor R ₁
Voltage V between the first transistor Q ₁ which is connected, a first control circuit for controlling the first transistor is connected to the first base of the transistor Q _1, the charging terminals 11 and 12 to
₁ constantly detect, compare the detected voltage and the first voltage comparison circuit that generates a command signal for voltage controlled as compared with the reference value, and detects the charging current I ₁ at all times, the detected current with a reference value And a shared constant current comparison circuit for generating a current control command signal.

The first control circuit for controlling the first transistor, an operational amplifier IC ₅ whose output terminal is connected to the base of the transistor Q ₁ via a resistor R _25, the operational amplifier I
Consisting of the transistor control reference voltage circuit shared for applying a reference voltage V _ref1 to the inverting input terminal of the C _5. This shared transistor control reference voltage circuit includes a resistor voltage dividing circuit of a resistor R ₁₇ and a resistor R ₁₉ connected between the common side power supply terminal 32 of the power supply 30 and the reference voltage terminal 33.

[0017] The first voltage comparator circuit comprises an operational amplifier IC its output terminal through a series circuit of a resistor R ₂₃ and diode D _3
5 , an operational amplifier IC ₃ connected to the non-inverting input terminal of
Reference voltage V _ref2 to the inverting input terminal of the operational amplifier IC ₃
And a common voltage control reference voltage circuit for applying a voltage, and the voltage of the plus side charging terminal 11 of the first charging circuit to the operational amplifier I
And a resistor R ₁₅ Metropolitan convey to the non-inverting input terminal of C _3. The voltage control reference voltage circuit for sharing a resistor divider common side power supply terminal 32 and the resistor connected between the reference voltage terminal 33 R ₁₁ and the resistor R ₁₃ of the power supply 30.

The second charging circuit for charging the battery 20 connected between the pair of charging terminals 21 and 22 has a collector connected to the positive charging terminal 21 and an emitter connected to the current detecting resistor R. Power supply terminal 3 of power supply 30 through ₁
A second transistor Q ₂ to which are connected to one, and a second control circuit for controlling the second transistor is connected to the second transistor Q ₂ of the base, constantly detects the voltage V ₂ between the charging terminal 21 and 22 and, a second voltage comparator circuit the detected voltage to generate a voltage control command signal by comparing with the reference value, and detects the charging current I ₂ at all times, the current control command by comparing the detected current with a reference value And a shared current comparison circuit for generating a signal.

A second control circuit for controlling the second transistor has an operational amplifier IC ₆ whose output terminal is connected to the base of the transistor Q ₂ via a resistor R ₂₆ , and a reference voltage V which is applied to an inverting input terminal of the operational amplifier IC _{6. ref1} is applied to the above-mentioned common transistor control reference voltage circuit.

[0020] The second voltage comparator circuit comprises an operational amplifier IC its output terminal through a series circuit of a resistor R ₂₄ and diode D _4
6 , an operational amplifier IC ₄ connected to the non-inverting input terminal of
The reference voltage V _{ref2 is} applied to the inverting input terminal of the operational amplifier IC _4.
A voltage control reference voltage circuit shared above for applying a, a resistor R ₁₆ Metropolitan convey a voltage of positive charge terminal 21 of the second charging circuit to the non-inverting input terminal of the operational amplifier IC _4.

The above-mentioned common current comparison circuit is provided with a power supply 30.
Source terminal 31 and transistor Q₁And transistor Q₂husband of
Current detecting resistor R inserted between each emitter
₁And its output terminal is a resistor R_{twenty one}And diode D₁Series
Operational amplifier IC through circuit₅Connected to the non-inverting input terminal of
And resistance R_{twenty two}And diode D₂Through a series circuit of
Amplifier IC₆Operational amplifier connected to the non-inverting input terminal of
IC₁And this operational amplifier IC₁To the inverting input terminal of
Pressure V_refThe resistance R that conveys₉And this operational amplifier I
C₁Input terminal and current detection resistor R₁Between one end of
The resistor R connected to ₇And the current detection resistor R₁And the other end of
Divide voltage between common line and operational amplifier IC₁Non
Resistance R given to inverting input terminal₅And resistance R₆Partial pressure consisting of
And a circuit.

Next, a first charging circuit in the case where a fully-discharged lithium ion battery 10 and a 50% -discharged lithium ion battery 20 are simultaneously charged by the charger of one embodiment of the present invention configured as shown in FIG. And the operation of the second charging circuit will be described with reference to the characteristic curve diagram of FIG. Here, the set voltage of the charger is 4.2 V, and the set current is 1 A.

[0023] From the start of charging until the time _{t 1,} an operational amplifier IC ₃ and the operational amplifier IC _4, since the configuration to the inverted input terminal voltage 4.2V less voltage is applied, the output is either LOW . Also, the current detection resistor R
₁ has become a 1A set current, the operational amplifier IC ₁ 'and its output and its inverting input is HIGH has become HIGH. Therefore, the operational amplifier IC ₅ and the operational amplifier IC
₆ has an operational amplifier IC at its inverting input terminal.
₁ output voltage is applied. Thus, in the first charging circuit supplies a charging current _{I 1} first transistor _{Q 1} is controlled by operational amplifier IC ₅ to the battery 10. At the same time, in the second charging circuit, a second transistor _{Q 2} is controlled by the operational amplifier IC ₆ cell 20
Supplying the charging current _{I 2} in.

Therefore, the time t from the start of charging₁Until
Charging current I₁And terminal voltage V₁Is as shown in FIG.
All of them gradually rise. Similarly, from the start of charging
Time t ₁Until the charging current I₂And terminal voltage V₂Figure 3
As shown in (B), each of them gradually rises. In addition,
Flow detection resistor R₁1A flowing through the charging current I₁
And charging current I₂The current is the sum of
For I₁And I₂Were both set to 0.5A.

[0025] Time _t charging terminal voltage _{V 2} to ₁ is to have reached the set voltage 4.2 V, the output of the operational amplifier IC ₄ is higher than the output voltage of the operational amplifier IC _1. Then
The output of the operational amplifier IC ₆ is raised, thereby reducing the charging current I ₂ is a second transistor Q ₂ in the collector current. Therefore, after time _{t 1,} the charging current _{I 2} is as shown in FIG. 3 (B), gradually decreases from 0.5A.

[0026] On the other hand, voltage _{V 2} between the charging terminal operational amplifier I
Since the constant voltage is controlled by a constant voltage control circuit including C ₄ , operational amplifier IC _6, and second transistor Q ₂ , as shown in FIG. 3B, the set voltage is 4.2 V after time t _1.
Is held.

Charging current I₂Is the charge current I₁Increase
It will be added. That is, the current detection resistor R₁Is the charging current I₂
Operational amplifier IC₁Through operational amplifier
IC ₄Tell Therefore, the operational amplifier IC₄Output voltage
Is reduced by that amount, so that the first transistor Q₁No
Lector current rises. Thus, the time t₁Or later
Is the charging current I₁Is 0.5 A, as shown in FIG.
Then increase the rate of increase and further increase. Also, between the charging terminals
Voltage V₁Is increased by increasing the rate of increase as shown in FIG.
Go.

[0028] Then, when the voltage _{V 1} between the charging terminals at the time _{t 3} has reached the set voltage 4.2V, the operational amplifier IC ₃
The output is higher than the output voltage of the operational amplifier IC _1.
Then, the output of the operational amplifier IC ₆ is raised, thereby the first transistor to Q ₁ collector current, thus reducing the charging current I _1. That time t ₃ after the charging current I ₁ of the first charging circuit, as shown in FIG. 3 (A), gradually decreases from the peak value at time t _3. Time _{t 3} is,
This is the time when the terminal voltage of the completely discharged battery 10 reaches the set voltage, and after this time, the current flowing out of the shared constant current control circuit becomes equal to or less than the set current value.

[0029] On the other hand, voltage _{V 1} between the charging terminal operational amplifier I
Since the constant voltage is controlled by a constant voltage control circuit including C ₃ , the operational amplifier IC ₅ and the first transistor Q ₁ , as shown in FIG. 3A, the set voltage is 4.2 V after time t _3.
Is held.

3 and 4, it can be easily understood that when a plurality of batteries are charged simultaneously, the charging time of the charger according to the present invention is shorter than that of the conventional charger. . Also, when charging only one battery, it is clear that the charging time of the charger according to the present invention is shorter than that of the conventional charger.

As described in detail above, in the present invention, in a charger for charging a plurality of batteries at the same time, constant voltage control is individually performed so as to maintain a charging voltage between respective charging terminals at a constant voltage value. In addition, constant current control is performed so that the sum of the respective charging currents is maintained at a constant current value.

In the circuit shown in FIG. 1 according to an embodiment of the present invention, in a charger comprising a plurality of charging circuits each having a main transistor, the charging voltage of each charging circuit is individually monitored by the voltage monitoring means and the main transistor. , And the sum of the charging currents of the charging circuits is controlled by a plurality of feedback circuits including a common current monitoring unit and a main transistor of each charging circuit. . The voltage monitoring means may include an operational amplifier IC in the first charging circuit.
₃ and a circuit including the operational amplifier IC ₄ in the second charging circuit. Furthermore, common current monitoring means described above, a circuit which includes a current detection resistor R ₁ and an operational amplifier IC _1.

[0033]

According to the present invention, the charging time can be shortened in a charger for simultaneously charging a plurality of batteries requiring constant voltage control, for example, a plurality of lithium ion batteries. Moreover, the more batteries that are simultaneously charged, the more remarkable the effect of the charger of the present invention in reducing the charging time.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of a two-output charger according to the present invention.

FIG. 2 is a circuit diagram of one embodiment of a conventional two-output charger.

FIG. 3 is a diagram showing a charging characteristic curve of the two-output charger according to the present invention.

FIG. 4 is a diagram showing a charging characteristic curve of a conventional two-output charger.

[Description of Signs] 10 Battery 11 Charging Terminal 12 Common Charging Terminal 20 Battery 21 Charging Terminal 22 Common Charging Terminal 30 Power Supply 31 Power Supply Terminal 32 Common Power Supply Terminal 33 Reference Voltage Terminal Q ₁ First Main Transistor Q ₂ Second Main transistor IC ₁ First current monitoring operational amplifier IC ₂ Second current monitoring operational amplifier IC ₃ First voltage monitoring operational amplifier IC ₄ Second voltage monitoring operational amplifier IC ₅ First transistor controlling operational amplifier IC ₆ Second transistor control operational amplifiers R ₁ , R ₂ Current detecting resistors R _{3 to} R ₂₆ Resistors D _{1 to} D ₄ Diode

Claims (2)

[Claims] In a charger for simultaneously charging a plurality of batteries, constant voltage control is individually performed so as to maintain a charging voltage between respective charging terminals at a constant voltage value, and a current equal to a sum of respective charging currents is provided. A constant current control is performed so as to maintain a constant current value. 2. A charger comprising a plurality of charging circuits each having a main transistor, wherein a charging voltage of each charging circuit is controlled by a constant voltage by an individual voltage monitoring means and a feedback circuit including the main transistor. A charger characterized in that the sum of the charging currents of the circuits is controlled by a plurality of feedback circuits including a common current monitoring means and a main transistor of each charging circuit.