JPH08275404A - Charging circuit - Google Patents

Abstract

PURPOSE: To provide a charging voltage circuit capable of charging electricity efficiently and sufficiently to a battery through an internal resistance. CONSTITUTION: Voltages at connecting points between a battery 5 of a battery pack 3 and internal resistors Ri1 and Ri2 are detected by a monitor amplifier, an error signal corresponding to the difference between a monitor signal detected by the monitor amplifier 7 and the reference voltage VZD is detected by an error amplifier 9, a control element 4 is controlled, and a voltage between the voltage output terminals T1 and T3 of the battery pack 3 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging circuit, and more particularly to a charging circuit for charging a battery via an internal resistance. Generally, when charging a battery, install a charging device because applying a voltage that is higher than the maximum output voltage of the battery will damage the battery, and charging with a voltage that is too low will require charging time. Charging should be done at the optimum voltage.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing an example of a conventional charging circuit. The conventional charging circuit 11 is activated by the voltage from the AC adapter 14 and generates an error signal according to the voltage of the battery pack 12. An error signal generation unit 13 and a power supply according to the error signal generated by the error signal generation unit 13 The control element 15 controls the supply of current from the battery pack 14 to the battery pack 12.

The AC adapter 14 is connected to an AC power supply such as a commercial power supply and converts an AC voltage supplied from the AC power supply into a DC voltage of a predetermined voltage and outputs the DC voltage. AC adapter 14
In transformed output DC voltage is supplied to the terminal T ₁₁ of the error signal generator 13, it is supplied to the terminal T ₁₂ of the battery pack 12 via the control element 15.

The error signal generator 13 comprises a one-chip monolithic IC (Integrated Circuit), and voltage control for controlling the supply voltage to the starter circuit 16 and the battery pack 12 which are activated by the DC voltage from the AC adapter 14 to be constant. It is composed of a circuit 17. The starting circuit 16 is connected to the terminal T ₁₁ to which the DC voltage from the AC adapter 14 is supplied. When the DC voltage is supplied from the AC adapter 14, the starting circuit 16 supplies the voltage to the internal circuits such as the error signal generating unit 13. ,
The internal circuit is activated so that the control element 15 is turned on.

The error signal generator 13 includes resistors R ₁₁ and R ₁₂ that divide the voltage applied between the terminals T ₁₃ and T ₁₄ , a current source 18 that generates a reference voltage, a Zener diode D ₁₁ and a resistor R ₁₁ ,
Error amplifier (operational amplifier) 19 that generates an error signal according to the difference voltage between the voltage divided by R ₁₂ and the reference voltage
Be more configuration will be output from the pin T ₁₅ an error signal corresponding to the difference between the terminal T _13, the divided voltage V ₁₁ corresponding to the applied voltage between T ₁₄ and the reference voltage V _f.

The control element 15 is a P-channel type MOS-FE.
T (Metal-Oxide-Semicouductor type Field Effect Trans
istor). AC is used as the source of the control element 15.
DC voltage converted by the adapter 14 output is supplied, the drain is connected to the terminal T ₁₃ of the terminal T ₁₂ and the error signal generation unit 13 of the battery pack 12, the gate is connected to a terminal T ₁₅ of the error signal generator 13 To be done.

The control element 15 controls the current supply from the AC adapter 14 to the terminal T ₁₂ to be small when the error signal is large,
When the error signal is small, it is controlled to be small. The battery pack 12 is composed of a battery 20 to be charged and internal resistors R _i11 and R _i12 that control the current from the battery 20. The battery 20 is a rechargeable battery such as a lithium-ion battery, the positive electrode is connected to the positive output terminal T ₁₂ via the internal resistance R _i11 , and the negative electrode is connected to the negative output terminal T ₁₆ via the internal resistance R _i12. Connected.

During charging, the terminal T of the battery pack 12₁₂Is wrong
Terminal T of the differential voltage generator 13₁₃Connected to the terminal T₁₆Is the edge
Child T₁₄Connected to and grounded. At this time, the conventional charging
Terminal T on path 11₁₃, T₁₄Detects the voltage between the terminals
T ₁₃, T₁₄It is configured to keep the voltage applied to
I was

FIG. 4 shows an operation waveform diagram of a conventional example. Therefore, when the voltage V ₂ is applied between the terminals T ₁₃ and T _{14 as} shown by the broken line in FIG. 4, the voltage V ₁ dropped to the battery 20 by the internal resistances R _i11 and R _i12 shown by the solid _lines in FIG. Will be applied.

[0010]

However, in the conventional charging circuit, the voltage of the external output terminal of the battery pack 12 is detected, and the current from the power source is controlled so that the voltage of the external output terminal of the battery pack becomes a constant voltage. Therefore, the voltage is applied to the battery 20 via the internal resistances R _i1 and R _i2, and therefore the voltage actually applied to the battery is smaller than the voltage capable of efficiently charging the battery. It cannot be charged efficiently.

Further, when the charging voltage is set to a large value, there is a problem that a large current may flow into the battery and the battery may be damaged. The present invention has been made in view of the above points, and an object of the present invention is to provide a charging circuit that can perform efficient and sufficient charging.

[0012]

In order to solve the above-mentioned problems, the present invention provides a charging circuit for supplying a charging current from a charging power source to a battery to be charged through an internal resistor for charging. Voltage detecting means for detecting the voltage at the connection point between the internal resistance and the internal resistance, reference voltage generating means for generating a reference voltage, detection voltage detected by the voltage detecting means, and reference generated by the reference voltage generating means. A configuration including a differential voltage detection unit that detects a differential voltage from the voltage, and a control element that controls the supply of a charging current from the charging power supply to the battery according to the differential voltage detected by the differential voltage detection unit. And

[0013]

According to the present invention, by connecting the voltage detecting means to the connection point between the internal resistance and the battery, the voltage of the battery itself, which does not include a voltage drop due to the internal resistance, can be detected by the voltage detecting means. The charging current supplied from the charging power source to the battery via the internal resistance can be controlled according to its own voltage.

Therefore, it is possible to control the battery so as to supply the optimum current that can be efficiently charged without damaging the battery, and it is possible to shorten the charging time and increase the charging amount. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit configuration diagram of an embodiment of the present invention. The charging circuit 1 according to the present embodiment is provided inside the current pack 3 and a control element 4 that controls the current supplied from the AC adapter 2 to the battery pack 3, and includes a battery 5 in the battery pack 3 and internal resistors R _i1 and R _i2 . It is connected to the connection point, is activated by the detection resistors R ₁ and R ₂ that limit the current from the battery 5, and the voltage from the AC adapter 2, and is driven by the charging voltage after activation and detected by the detection resistors R ₁ and R _2. The error signal generating circuit 6 controls the control element 4 by generating an error signal according to the detected voltage.

The AC adapter 2 is connected to an AC power source such as a commercial power source and converts an AC voltage supplied from the AC power source into a DC voltage of a predetermined level set in advance and outputs the DC voltage. A
The DC voltage output from the C adapter 2 is supplied to the error signal generation circuit 6 and the battery pack 3 via the control element 4.

The battery pack 3 is a battery 5 to be charged, internal resistances R _i1 and R _{i2 for} protecting the battery 5 from overcurrent at the time of power supply, and a detection resistance R for detecting the voltage from the battery 5 at the time of charging.
_It is composed of ₁ and R ₂ . The battery 5 is composed of a rechargeable battery such as a lithium ion battery. The positive electrode of the battery 5 is connected to the output terminal T ₁ via the internal resistance R _i1 and the detection element T ₂ via the detection resistance R ₁ , and the negative electrode is output via the internal resistance R _i2. It is connected to the terminal T ₃ and also to the detection terminal T ₄ via the detection resistor R ₂ .

Output terminal T of battery pack₁, T₃, Detection end
Child T₂, T_FourIs the drive voltage of the error signal generation circuit 6 during charging.
Pressure terminal T_Five, Ground terminal T₆And detection terminal T₇, T₈Contact
Continued. The error signal generation circuit 6 is a monolithic IC (In
integrated circuit) detection terminal T₇, T₈Electricity between
Monitor amplifier 7, terminal for generating monitor signal according to pressure
T _Five, T₆A reference that generates a constant reference voltage from a voltage between
Monitor signal monitored by voltage circuit 8 and monitor amplifier 7.
And the difference between the reference voltage generated by the reference voltage circuit 8 is detected
Error amplifier that generates an error signal according to the detected difference
9. Monitor when the DC voltage is input from the AC adapter 2.
Start-up circuit for starting the amplifier 7, reference voltage circuit 8 and error amplifier 9
It is composed of the passage 10.

The monitor amplifier 7 is composed of an operational amplifier circuit, the non-inverting input terminal is connected to the detection terminal T ₇ , the inverting input terminal is connected to the detection terminal T ₈ , and the power supply terminal is connected between the terminals T ₅ and T _6. , Terminals T ₅ and T ₆ are driven. The monitor amplifier 7 generates and outputs a monitor signal according to the voltage between the terminals T ₇ and T ₈ .

The reference voltage circuit 8 is composed of the terminal T _5, T constant current source connected in series with each other between ₆ 8a and a zener diode D _1. One end of the constant current source 8a is a terminal T ₅
And the other end is connected to the cathode of the Zener diode D ₁ . The Zener diode D ₁ has its anode connected to the terminal T ₆ . A constant current is supplied to the Zener diode D ₁ by the constant current generator 8a. Therefore, a Zener voltage V _ZD of a constant level is generated between the cathode and the anode of the Zener diode D ₁ . The reference voltage circuit 8 outputs the connection point between the constant current source 8a and the Zener diode D ₁ and outputs the Zener voltage V _ZD as the reference voltage.

The error amplifier 9 comprises an operational amplifier circuit,
The output monitor signal of the monitor amplifier 7 is supplied to the non-inverting input terminal, the reference voltage generated by the reference voltage circuit 8 is supplied to the inverting input terminal, and the monitor signal from the monitor amplifier 7 and the reference voltage of the reference voltage circuit 8 are supplied. An error signal is generated according to the difference from the voltage. The error amplifier 9 is connected between terminals T _5, T _6, it is driven by the voltage between the terminals T _5, T _6.

The output error signal of the error amplifier 9 is the terminal T₉To
Supplied. Terminal T₉Is the control element T ₉Is supplied to. end
Child T₉Is connected to the control terminal of the control element 4. Control element
4 is composed of a P-channel MOSFET, and the gate is at the end
Child T₉And the source is connected to the AC adapter 2.
And the drain is the terminal T of the error signal generator 6._FiveConnected to
It

The control element 4 controls so as to control the supply of the direct current from the AC adapter 2 to the terminal T _{1 as} the error signal from the terminal T ₉ increases. The starting circuit 10 is A
It is connected to the terminal 10 connected to the connection point between the C adapter 2 and the control element 4, and AC regardless of the state of the control element 4.
It is similarly driven by the direct current from the adapter 2.

When charging the battery pack 3, a battery is used.
Terminal T of pack 3₁Is a terminal T of the error signal generation circuit 6._FiveTo
Connect to the terminal T of the battery pack 3₃Error signal generation circuit 6
Terminal T₆Connected to the detection terminal T of the battery pack 3₂Wrong
Detection terminal T of the difference signal generation circuit 6₇Connect to the battery pack
3 detection terminals T_FourIs a detection terminal T of the error signal generation circuit 6. ₈
Connect to.

Next, the operation of this embodiment will be described. FIG. 2 shows an operation waveform diagram of one embodiment of the present invention. First, when the AC power source is turned on and the DC voltage is output from the AC adapter 2, the starting circuit 10 is driven and the error signal generating circuit 6 is started.

Next, when power is consumed and the consumed battery pack 3 is connected to the corresponding terminal of the error signal generating circuit 6 via a connector or the like, charging of the battery pack 3 is started.
When charging is started, the voltage of the battery 5 is small at first, the output monitor signal of the monitor amplifier 7 is small, and the difference from the reference voltage is large, so that the output error signal of the error amplifier 9 is large.

Therefore, the current flowing through the control element 4 increases, and the charging current is supplied to the battery 5. At this time, since the charging current is controlled according to the voltage of the battery 5, the terminals T ₁ and T
₅ , the optimum voltage V ₂ for the battery 5 is shown by the broken line in FIG.
A larger voltage V ₃ is applied, and the optimum voltage V ₂ for charging the battery 5 can be applied to the battery 5 without being affected by the internal resistances R _i1 and R _i2 as shown by the solid line in FIG. For this reason,
The most chargeable current can be supplied most efficiently without damaging the battery 5.

[0028] Thus, can be charged in accordance with only the characteristics of the battery 5, the internal resistance R _i1, the influence of R _i2 is not subjected, the internal resistance R _i1, R _i2 battery even for different battery packs If the charging voltage of 5 is the same, charging is possible.

[0029]

As described above, according to the present invention, by connecting the voltage detecting means to the connection point between the internal resistance and the battery, the voltage detecting means detects the voltage of the battery itself not including the voltage drop due to the internal resistance. Since the charging voltage supplied from the charging power source to the battery via the internal resistance can be controlled according to the voltage of the battery itself, the battery can be charged efficiently without being damaged. It is possible to control so as to supply an optimum voltage, and has features such as shortening the charging time and increasing the charging amount.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of an embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a conventional example.

FIG. 4 is an operation waveform diagram of a conventional example.

[Explanation of symbols]

1 charger 2 AC adapter 3 Battery pack 4 control element 5 cell 6 the error signal generating circuit 7 monitors the amplifier 8 reference voltage circuit 9 error amplifier 10 starts amplifier R _1, R ₂ detection resistor R _i1, R _i2 internal resistance

Claims (1)

[Claims] 1. A charging circuit for supplying a charging current from a charging power source through an internal resistance to a battery to be charged for charging, and detecting a voltage at a connection point between the battery and the internal resistance. A detection means, a reference voltage generation means for generating a reference voltage, a detection voltage detected by the voltage detection means, and a differential voltage detection means for detecting a difference voltage between the reference voltage generated by the reference voltage generation means, And a control element that controls the supply of a charging current from the charging power source to the battery according to the difference voltage detected by the difference voltage detection means.