KR930009601B1 - Battery charge control circuit - Google Patents

Abstract

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Description

Battery charge control circuit

1 is a conventional battery charge control circuit diagram.

2 is a block diagram of a battery charge control circuit of the present invention.

3 is a detailed circuit diagram showing another embodiment of the present invention.

4 is a waveform diagram showing voltage distribution for displaying a battery discharge state of the present invention.

5 is an explanatory view showing the discharge state light emitting diodes LD1-LD4 of the present invention.

* Explanation of symbols for main parts of the drawings

1: power supply 2: timer and charge control unit

3: switch part 4: discharge end detection part

5: initial timer control unit 6: discharge end control unit

7: discharge state display part R1-R23: resistance

Q1-Q7: transistor LD1-LD4: light emitting diode

ZD1-ZD5: Zener Diodes D1-D3: Diodes

PO1-PO5: Operational Amplifier RY1: Relay

C1, C2: Capacitor SW1: Tact Switch

VR1: Variable resistor

The present invention relates to a charge control circuit of a nickel-cadmium (Ni-Cd) battery, and in particular, to compensate for the shortcomings of the conventional battery in which the capacity of the battery is reduced due to the memory effect of the nickel-cadmium battery. The present invention relates to a battery charging circuit with a built-in battery discharge device capable of completely discharging and fully charging to eliminate a memory effect.

In the conventional nickel-cadmium battery charge control circuit, as shown in FIG. 1, a power supply unit 1 to which a DC power source DC is supplied, and an output power supply from the power supply unit 1 is a current limiting resistor R1. And voltages Vd1 and Vd2 detected at both ends of the resistor R1 through the non-return diode D1 and applied to the grounded battery Bt1, thereby charging the current of the power supply unit 1. Or a timer and a charge control unit 2 which controls the voltage and performs charge control by a timer.

In the conventional battery charge control circuit configured as described above, the DC power supply DC supplied from the power supply unit 1 supplies current to the battery Bt1 through the DC limiting resistor R1 and the backflow prevention diode D1.

In this case, in the case of a simple charger, charging starts by a timer without input of the voltages Vd1 and Vd2 between the resistors R1, and after a predetermined time passes, the timer and the charging control unit 2 output a control signal. In the case of a more complicated charger which cuts off the power supply of the power supply unit 1 and limits the current, the charging control is performed by the voltages Vd1 and Vd2 detected at both ends of the resistor R1. In addition, control is performed by a timer.

When the detection signal of the timer and the charging control unit 2 reaches the charging end time, the control signal is output to the power supply unit 1 to terminate the charging.

However, in such a battery charge control circuit, full discharge of the used battery is not guaranteed.

In other words, batteries used in razor camcorders, audio and cassettes, etc., cannot guarantee that the battery will always be used until the user has discharged completely.

That is, only 10% of the battery capacity may be used and left, or 50% may be used and left.

This is because the discharge state of the battery is different according to the user's product handling and usage habits. Especially, the capacity of the original battery is considerably reduced due to the memory effect, which causes inconvenience to the user.

Here, the memory effect is one of the biggest drawbacks of the nickel-cadmium battery, and discharges only 50% of the battery having a capacity of "100", for example, fully charges it again, and uses only 50% again (discharged). After recharging, the capacity of the nickel-cadmium battery is reduced to 50, which is a frequently used capacity. Accordingly, when discharged to full capacity, only about 50 capacity is obtained.

Therefore, there is a problem that affects the aging of the battery, decrease in capacity and decrease in reliability.

The present invention creates a battery charge control circuit that can almost recover the original capacity of the battery when the battery is fully discharged and then recharged three times in a way to eliminate the memory effect in order to solve such a conventional problem. If it is described with reference to the accompanying drawings as follows.

2 is a block diagram of the battery charge control circuit of the present invention, Figure 3 is a detailed circuit diagram showing an embodiment according to the present invention, as shown therein, the power supply unit 1 is supplied with a DC power (DC) The power output from the power supply unit 1 is applied to the grounded battery Bt1 through the current limiting resistor R1 and the backflow prevention diode D1, and is detected at both ends of the resistor R1. In the battery charge control circuit composed of a timer and a charge control unit (2) which controls the charging current and voltage of the power supply unit (1) by the supplied voltages (Vd1) and (Vd2) and charge control by a timer. The cathode side of the diode D1 is connected to one fixed terminal NC of the relay switch connected in parallel with the position Sw1, and the battery Bt1 and ground are connected to the movable terminal C and the other fixed terminal No. The discharge unit R3 connected to the switch unit 3, After the input voltage through the other fixed terminal (No) of the relay switch of the switch unit (3) is connected through the resistor (R3) and the capacitor (C1) connected in parallel and grounded resistor (R4) and inverting input terminal (-) The non-inverting input terminal (+) of the operational amplifier OP1 connected to the anode of the diode D1 through the variable resistor VR1 and the grounded zener diode ZD1 and the resistor R7 is connected thereto. The discharge end detection unit 4 for applying the output of the associating amplifier OP1 to the timer and the charge control unit 2, and the voltage through the other fixed terminal No of the switch unit 3 to the capacitor C2 and the ground. And then connected to the base of transistor Q1 where the emitter is grounded through resistor R5 and grounded resistor R6, and the collector output of transistor Q1 is connected to the discharge termination. An initial timer controller 5 applied to the inverting input terminal (-) of the associating amplifier OP1 of the detector 4 and one side of the resistor R1; The diode D3 and the PNP transistor Q2 are connected in parallel to the anode connection point of the diode D1, and the base and the emitter of the PNP transistor Q2 are grounded through the resistors R8 and R9. Is connected to the collector of the transistor Q3, and the switch control relay RY1, which is grounded and controls the switch unit 3, is connected to the collector of the PNP transistor Q2, while the base of the transistor Q3 is connected. The discharge end control section 6, which is connected to the input side of the timer and the charge control section 2 and the output end of the discharge end detection section 4 by connecting a grounded resistor R10 and a resistor R11, and the switch section 3 Grounded resistors and capacitors (R16, C3), (R17, C4), (R18, C5), after the battery voltage (Vd) through the other fixed terminal (No) of) through Zener diodes (ZD2-ZD5) Operational amplifier O to which a constant reference voltage Verf is applied to the inverting input terminal (-) through (R19, C6), respectively It is applied to the non-inverting input terminal (+) of P2-OP5) and compared, and the output of the operational amplifier OP2-OP5 is the transistor (Q4-Q7) in which the emitter is commonly grounded through the resistors R20-R23, respectively. Are applied to the bases of the transistors, and outputs through the switch control relay RY1 of the discharge termination controller 6 through the resistors R12-R15 and the light emitting diodes LD1-LD4, respectively. And a discharge state display unit 7 which is applied to the collector and displays the discharge state.

The operation and effects of the present invention configured as described above will be described with reference to FIGS. 4 and 5.

First, when the user presses the tack switch SW1 once, the DC battery power supply DC supplied to the power supply unit 1 at the moment of pressing the other fixed terminal (No) of the relay switch through the resistor R1 and the diode D1. Is applied to the capacitor C2 of the initial timer control unit 5, and the diode D2 grounded at the base of the transistor Q1 until the capacitor C2 is fully charged. Since the initial voltage through the resistors R5 and R6 is applied, the transistor Q1 is turned on.

At this time, the charging time of the capacitor C2 is determined by the resistor R5 which is a time constant, and since the transistor Q1 is turned on, the collector output of the transistor Q1, that is, the output of the initial timer control unit 5 It becomes " low level " and is applied to the inverting input terminal (-) of the operational amplifier OP1 of the discharge end detector 4, and an input voltage through the resistor R7 is applied to the variable resistor VR1 and the zener diode ZD1. When the initial power is applied, input power is applied to both ends of the resistor R4 as it is until the capacitor C1 of the discharge termination detector 4 is charged. Therefore, the non-inverting input terminal (+) of the operational amplifier OP1 It becomes "high level" and the output of the operational amplifier OP1 becomes "high level".

Therefore, the output of the discharge termination detector 4 is applied to the base of the transistor Q3 through the resistor R11 and the grounded resistor R10 of the discharge termination controller 6 in a "high level" state, and thus the transistors. Q3 is turned on and the PNP transistor Q2 is turned on so that the switch control relay RY1 is turned on, and the movable terminal C of the relay switch of the switch unit 3 is the other fixed terminal (No). ), The battery (Ot1) power is discharged through the resistor (R2).

In addition, the collector output voltage of the PNP transistor Q2 is supplied to the power supply of the light emitting diodes LD1-LD4 through the resistors R12-R15 of the discharge state display unit 7, respectively, while the battery voltage Vd is applied. Is the non-inverting input terminal (+1) of the operational amplifier (OP2-OP5) when the voltages (V1-V3, Vcut) due to the Zener diodes (ZD2-ZD5), time constants (R16-R19), (C3-C6) At this time, because the Zener voltage is set differently, V1-V3 and Vcut voltage are different, and if the Zener voltage is set to V _ZD2 > V _ZD3 > V _ZD4 > V _ZD5 , the voltage is Vcut>V3>V2> V1. When the full charge is applied, the V1-V3 and Vcut voltages are higher than the reference voltage Vref applied to the inverting input terminal (-) of the operational amplifiers OP2-OP5, so that the calculations pass through the resistors R20-R23, respectively. Since the outputs of the amplifiers OP2-OP5 are applied to the base of the transistors Q4-Q7 at a "high level", the transistors Q4-Q7 are turned on. All four light emitting diodes LD-LD4 are turned on, but as the battery Bt1 gradually discharges, the voltage V1 applied to the non-inverting input terminal (+) of the operational amplifier OP2 is the inverting input terminal (-). When the light emitting diode LD1 is lower than the reference voltage Vref, the light emitting diode LD1 blinks, and the light emitting diodes LD1-LD4 are sequentially turned off as they are discharged.

That is, as shown in FIG. 4, when the battery Bt1 has a full charge voltage Vo and a full discharge voltage Vcut, the remaining amount is about 75 due to the distribution of V1-V2 and Vcut battery voltage Vd. If more than% is left, the battery voltage (Vd) becomes more than V1, if more than 50% and less than 75%, the voltage is between V1 and V2, and if more than 25% and less than 50% is between V2 and V3, 0% Set the voltage to V3 to Vcut when the value is less than 25%.

Accordingly, as the battery Bt1 is discharged as shown in FIG. 5 as the battery Bt1 is discharged, the light emitting diodes LD1-LD4 are gradually turned off from the front as shown in FIG.

On the other hand, after a certain time after the discharge of the battery Bt1, the capacitor C2 of the initial timer 5 is charged to turn off the transistor Q1, and both ends of the operational amplifier OP1 are connected to the voltage Vd of the battery. ) Is detected.

That is, when the voltage Vd of the battery is reduced and the last light emitting diode LD4 is turned off, the battery voltage Vd is at the level of the full discharge voltage Vcut, so that the output of the operational amplifier OP1 is “low”. Level ", and the transistors Q3 and Q2 of the discharge end control section 6 are turned off by the signal" low level "of the discharge end detection section 4, and all of the discharge state display section 7 are turned off. As the light emitting diodes LD1-LD4 are turned off and the switch control relay RY1 is also turned off, the movable terminal C of the switch section 3 is switched from the other fixed terminal No to the one fixed terminal NC. Discharge of (Bt1) ends.

On the other hand, the timer and the charge control unit 2 outputs a charge control signal to the power supply unit 1 by the output signal in the "low level" state of the discharge end detection unit 4 to start charging.

As described in detail above, in the case of a conventional nickel-cadmium battery charging control circuit or a system using a nickel-cadmium battery (particularly, a shaver and a camcorder), if the battery is repeatedly recharged without complete discharge of the battery, the capacity of the battery may increase due to the memory effect. Harden to the capacity you use often.

In other words, if the battery having the capacity of 100 is used by 50%, recharged, and then used again by 50%, the capacity of the battery decreases from the initial 100 to 50.

Therefore, the present invention can eliminate the memory effect by repeating the cycle of discharging the original battery 100%, fully recharging, and then fully discharging about three times, thereby helping in various aspects such as efficient use of the battery, cycle life, and reliability. In addition, since the charge state capacity of the battery is displayed through the light emitting diode, the charge state and discharge state of the battery can be checked at any time.

Claims (2)

The DC power supply DC through the power supply 1 is applied to the battery Bt1 through the resistor R1 and the diode D1, and is applied by the voltages Vd1 and Vd2 across the resistor R1. In a battery charge control circuit comprising a timer for controlling the power supply unit 1 and the charge control unit 2, a switch unit for switching the battery (Bt1) is fully discharged and fully charged by pressing the tack switch (Sw) ( 3), an initial timer unit 5 for charging the input voltage through the switch unit 3 to output a control signal based on a time constant, and an input voltage and the initial timer charged through the switch unit 3. A discharge end detection unit 4 which detects a complete discharge by the control voltage of the unit 5 and outputs a control signal to the timer and the charge control unit 2, and a switch by the control output signal of the discharge end detection unit 4; A discharge for controlling the switching unit 3 by driving a control relay RY1. A battery charge control circuit, characterized in that consisting of not detecting section (6). The light emitting diode of claim 1, wherein the light emitting diode supplied from the discharge end air unit 6 is outputted by comparing the battery discharge voltage Vd sensed by the zener voltage differently set by the switch unit 3 with a reference voltage. A battery charge control circuit comprising a discharge state display unit 7 that sequentially turns off.