KR950009298B1 - Alternation circuit of recharging mode for the battery - Google Patents

Abstract

The circuit switches charge mode from a CC mode to a CV mode according to the charge state of a secondary battery. The circuit includes a CC and a CV mode controller(23,24) for charging a battery with CC or CV mode, a power supply(22) for supplying power to a battery according to charge mode, a charge end detector(15) for detecting charge end of a battery, and a re-charge state detector(26) for recharging battery according to the state of a battery.

Description

Battery charge mode switching circuit

1 is a block diagram of a conventional battery constant voltage charging circuit.

2 is a block diagram of a conventional battery constant current charging circuit.

3 is a block diagram of a charging mode switching circuit of the battery of the present invention.

4 is a detailed circuit diagram of FIG.

* Explanation of symbols for main parts of the drawings

21: rectifier 22: operation unit

23: constant voltage controller 24: constant current controller

25: buffer voltage detection unit 26: recharge detection unit

27: latch portion 28: reference voltage portion

The present invention relates to a charging circuit of a secondary battery, and in particular, when charging, it is charged with a constant current to prevent the battery from being incompletely charged, and after a full charge, the battery can be switched to the constant voltage mode to prevent the charging voltage of the battery and overcharging. It relates to a charge mode switching circuit of a battery.

In the conventional battery constant voltage charging circuit, as shown in FIG. ₁ , a commercial AC voltage is stepped down through a transformer T ₁ , and a rectifier 1 for rectifying the stepped AC voltage to DC, and the rectifier 1 ) And a constant voltage section (2) for setting the voltage output from the battery to the buffer voltage of the battery, and a current limiting resistor (R ₁ ) for preventing overcurrent from flowing during initial charging of the battery (BT ₁ ).

In addition, the conventional constant current charging circuit of the battery has a commercial AC voltage stepped down through the transformer T ₁ as shown in FIG. 2, and a rectifying unit 11 for rectifying the stepped AC voltage to DC, and the battery at the time of charging. Regardless of the voltage rise of BT ₁ , the constant current unit 12 for supplying a constant current from the rectifying unit 11 and the buffer voltage of the battery BT ₁ are sensed to cut off the constant current unit 12. It consists of a constant voltage detecting section 13, and a resistor R ₁₁ for creep charging which supplies a self-discharge by flowing a small current after buffering.

The conventional technical operation configured as described above is as follows.

First, the smoothing receives the pulsating voltage rectified in the first degree holding portion (1) at a constant voltage unit (2) and create a stable DC voltage to supply to the battery (BT _1), the charge voltage of the charge initially battery (BT ₁₎ Since the internal resistance value is low and the overcurrent flows, the constant voltage part 2 becomes unreasonable. Accordingly, the current limiting resistor R ₁ is connected in series between the battery BT ₁ and the constant voltage part 2. Insertion limits the maximum charging current.

In FIG. 2, the pulse current rectified by the rectifying unit 11 is supplied to the battery BT ₁ by controlling the constant current in the constant current unit 12.

At this time, in the even voltage is the voltage increase of the battery (BT _1), because it is higher than the full charging voltage of the battery (BT _1), the constant current portion 12 of the holding portion 11 always is charged at a constant current, the constant current unit ( 12) continues to charge the current even when the battery (BT ₁ ) is fully charged, the constant current unit 12 continues to flow current even when the battery (BT ₁ ) is fully charged, so the battery (BT ₁ ) in the constant voltage detection unit (13) Senses the full charge voltage, thereby stopping the constant current unit 12 to complete charging.

Then, the resistor R ₁₁ is connected in parallel with the constant current portion 12, and even after the full charge, a small current flows into the battery BT ₁ to charge the cree.

However, the conventional constant voltage charging method of the conventional battery is the safest method for the battery, but when the voltage of the battery rises to almost the same value as the constant voltage output under the influence of the current limiting resistance, the charging current decreases and it takes a long time to fully charge. As the battery is used for a long time, the charge completion voltage increases, thereby causing an incomplete charge state.

In the constant current charging method of the battery, if the charge completion detection voltage is set high enough to cope with the change of the battery, the problem in the constant voltage charging type can be solved, but there is a problem in that recharging cannot be performed automatically.

For example, in the case of a telephone handset, it needs to be recharged if it is disconnected from the main unit for a long time, and in this method, it is necessary to press the charge button manually to recharge it. Even if the phone is not used, even if the phone is removed from the main body even when combined with a constant current charge is performed, rather causing a problem in the battery.

In order to solve such a conventional problem, the present invention, in the charging circuit of the secondary battery, during initial charging, rapid charging is performed by the constant current charging method, and at some point, the charging is performed by switching to the constant voltage charging method, and then charging is performed. When the charging is completed, the battery is protected, and the charging mode switching circuit of the battery which automatically performs the entire process of charging is created. The detailed description with reference to the accompanying drawings is as follows.

FIG. 3 is a block diagram of a charging mode switching circuit of the battery of the present invention, and FIG. 4 is a detailed circuit diagram of FIG. 3. As shown therein, an AC voltage stepped down through a transformer T ₁ is applied to a diode D ₁ , The rectifier 21 rectified by (D ₂ ) and the output voltage of the rectifier 21 are smoothed by the capacitor C ₁ and made constant by the constant voltage integrated circuit VS _I and the capacitor C ₂ . After the voltage divider (R ₁ , R ₂ ), (R ₃ , R ₄ ), (R ₆ , R ₇ ) to make a reference voltage and supply it to each part, and supply a constant current during charging Constant current control unit 24 for detecting the error of the current through the operational amplifier (OP ₂ ) from the reference voltage of the resistors (R ₁ , R ₂ ) and the voltage applied to the resistor (R ₅ ), and the resistor (R ₆₎ , R ₇₎ a reference voltage and the battery (floating through the operational amplifier (OP ₁₎ from the voltage of the variable resistor (R ₉₎ according to the terminal voltage of the BT ₁₎ of Transistor (Q ₁₎ by the constant voltage control part 23, the constant voltage control part 23 and the constant current control section 24 to allow the former, (Q ₂₎ is operating the output of the rectifying section (21), the battery ( BT ₁ ) of the operation unit 22 to perform the constant voltage and constant current charging operation, and the reference voltage of the resistors R ₆ and R ₇ and the battery BT ₁ during the constant current charging according to the operation unit 22. A buffer voltage sensing unit 25 for detecting a fully charged voltage through the operational amplifier OP ₄ from the voltages of the variable resistor R ₈ and the capacitor C ₃ according to the charging voltage, and the resistors R ₃ and R _4. Recharge sensing unit 26 for detecting a current flowing in the constant voltage state through the operational amplifier OP ₃ from the reference voltage of the reference voltage and the voltage applied to the resistor (R ₅ ), and generates a signal to perform the constant current charging if a predetermined value or more. And the outputs of the recharge detection unit 26 and the buffer voltage detection unit 25. Lip-flop latch for switching the floating charge or the constant current charging mode of the constant voltage control part 23 and stores the state through the output terminal (Q) for receiving a set (S) and reset (R) terminal of the (FF ₁₎ It consists of a part 27.

Referring to the operation and effects of the present invention configured as described above in detail.

The AC voltage stepped down by the transformer T ₁ is rectified through the diodes D ₁ and D ₂ of the rectifier 21 and smoothed by the capacitor C ₁ , and the smoothed voltage is a constant voltage integrated circuit VS. _I) the condenser is at a constant voltage of + 5V by a (C ₂₎ charging and the charging voltage is the resistance (R _1, R ₂₎ of the capacitor (C _{2) to, (R 3, R 4)} , (R 6, The voltage is divided by R ₇ ) and applied to each part as a reference voltage.

At this time, when the battery BT ₁ is not coupled, the voltage smoothed in the capacitor C ₁ is applied to the base of the transistor Q ₂ through the resistor R ₁₀ , and the transistor Q ₂ is conducted. Transistor Q ₁ is conductive. Accordingly, the voltage smoothed in the capacitor C ₁ is output through the transistor Q ₁ , and the output voltage is charged through the variable resistor R ₈ and then charged in the capacitor C ₃ to the operational amplifier OP ₄ . Is compared with the reference voltage by the resistors R ₆ and R ₇ , whereby the charging voltage of the capacitor C ₃ As soon as it becomes higher, the high potential signal is output from the operational amplifier OP ₄ and the flip-flop FF ₁ is reset. Therefore, since the low potential signal is output to the output terminal Q of the flip-flop FF ₁ , the operational amplifier OP ₁ , which is the constant voltage control unit 23, operates to control the constant voltage.

That is, the voltage output through the transistor Q ₁ is applied to the inverting input terminal of the operational amplifier OP ₁ through the variable resistor R ₉ , and the reference voltage by the resistors R ₆ and R ₇ is applied. since the operation is the non-inverting input terminal of the amplifier (OP _1), according to the operational amplifier (OP ₁₎ the voltage applied to the inverting input terminal of the resistance (R _6, R ₇₎ a reference voltage Negative feedback is applied to the base of transistor Q ₁ so that it remains in the same state, and the emitter of transistor Q ₁ maintains a constant voltage.

Wherein the voltage and are aligned in a slightly higher voltage than the nominal voltage of the battery (BT ₁₎ by a variable resistor (R _9), wherein when binding the battery (BT ₁₎ used in the (B +), (B-) terminal voltage In this state, the charging current flows to the battery BT ₁ .

Thus, because the current through the battery (BT ₁₎ is run through a resistor (R _5), the connection point (b) of the resistor (R ₅₎ is the electric potential there is go up than the connection point (a), the potential at the connection point (b) resistance Reference voltage divided by (R ₃ ), (R ₄ ) When higher than an operational amplifier (OP ₃₎ the high potential signal is outputted is and sets the flip-flop (FF _1), whereby the high potential signal outputted to the flip-flop output terminal (Q) of (FF ₁₎ in accordance with the constant voltage from the The control terminal 23 is applied to the control terminal of the operational amplifier OP ₁ .

Accordingly, the operational amplifier OP ₁ stops the constant voltage control operation, so that the output voltage of the rectifying unit 21 is directly applied to the (B ⁺ ) terminal through the transistor Q ₁ , and the charging current is increased.

At this time, the connection point b of the resistor R ₅ becomes higher in potential than the connection point a due to the increased current, and this voltage is the reference voltage of the constant current controller 24, that is, the non-inverting of the operational amplifier OP ₂ . Reference voltage applied to input terminal If it goes higher, the output of the operational amplifier OP ₂ is at a low level, and the current of the transistor is reduced by dropping the base potential of the transistor Q ₁ , which is a negative feedback in operation. It is kept in the state.

That is, the constant current is supplied to the battery BT ₁ .

On the other hand, charging continues, and the voltage of the battery rises, and this voltage is applied to the operational amplifier OP ₄ of the buffer voltage detecting unit 25. Becomes higher than the operational amplifier is a high potential signal output from the (OP ₄₎ flip-flop (FF ₁₎ to Li was set, so that the flip-flop (FF ₁₎ is a low potential signal to the output terminal (Q) is the output of the The operational amplifier 23 again controls the constant voltage operation.

Since this state is lower than the charge completion voltage, the current decreases and falls below the recharge sensing current. In other words, the voltage of the battery BT ₁ is maintained as it is.

As described in detail above, the present invention charges with a constant current at the time of charging and switches to the constant voltage mode at some point to perform the floating charging in a fully charged battery while protecting the battery, after which the charging is completed, By automatically starting the charging, completion of charging, floating charging, etc., the battery can be quickly charged and fully charged by simply connecting the battery to the charger, and the battery can be protected.

Claims (1)

Rectifier 21 for rectifying the AC voltage stepped down through the transformer (T ₁ ), a reference voltage unit 28 for receiving the output voltage of the rectifier 21 and supplying a reference voltage to each sphere, and the reference voltage unit The constant voltage control unit 23 controls the floating charging by applying a constant voltage upon completion of charging according to the reference voltage of the battery and the charging voltage of the battery, and charges according to the reference voltage of the reference voltage unit 28 and the charging current of the battery. A constant current controller 24 for supplying a constant current at a time to control the constant current charging, and an operation unit 22 for charging the battery with the output voltage of the rectifier 21 under the control of the constant voltage controller 23 and the constant current controller 24. ), A buffer voltage detecting unit 15 for detecting a charging completion voltage according to the reference voltage of the reference voltage unit 28 and the charging voltage of the battery, and the reference voltage of the reference voltage unit 28 and the charging of the battery. Floating or constant current charging depending on current A recharge detection unit 26 for detecting whether to perform the operation, and a latch unit 27 for controlling driving of the constant voltage control unit 23 according to output signals of the buffer voltage detection unit 25 and the recharge detection unit 26. A charge mode switching circuit of a battery, which is configured.