KR100216627B1 - Detecting method for full-charge of a rechargeable battery, and the Apparatus thereof - Google Patents

Abstract

The present invention provides a full charge detection method of a rechargeable battery using a phenomenon in which the internal resistance of the battery is rapidly increased when the nickel-cadmium (Ni-Cd) or nickel-hydrogen (Ni-MH) battery is about 75 to 90% charged. As for the device,

In the part where the internal resistance of the battery increases rapidly during the charging process, the difference between the charger supply voltage and the battery terminal voltage increases rapidly during constant current charging.The difference between the two voltages is measured by alternating the charger supply voltage and the battery terminal voltage at an appropriate period during charging. By detecting the point where the battery starts to increase, it stops the rapid charging and switches to the final charging so that the battery can be fully charged while suppressing the temperature rise.

Description

Detecting method for full-charge of a rechargeable battery, and the Apparatus

The present invention relates to a full charge detection method and apparatus thereof for a rechargeable battery, and more particularly, to internal battery resistance generated near a full charge of a nickel-cadmium (Ni-Cd) or nickel-hydrogen (Ni-MH) battery. The present invention relates to a full charge detection method and apparatus for a rechargeable battery capable of detecting the sudden rise of the battery to fully charge the battery.

In general, a spent nickel-cadmium or nickel-hydrogen battery is recharged by using a battery charger, and then used again. At this time, a constant continuous current flows to the battery to recharge it. Rapid charging until the voltage peak) (hereinafter referred to as full charging) and the rest is charged by reducing the charging current.

As such, when charging the battery, various methods for detecting a full charge have been proposed to ensure that the battery is normally fully charged.

That is, a timer method for charging for a predetermined time after the start of charging, a falling reverse voltage (hereinafter, referred to as -ΔV) detecting the falling reverse voltage of the battery voltage to stop charging, and charging when reaching a certain temperature. The temperature detection method to stop and the slope change of the voltage rise are measured to determine the slope change of the voltage rise to stop charging when a predetermined slope change of the voltage rise occurs. ) Detection method is used.

Among these methods, the most commonly used method is a falling reverse voltage detection method. An example thereof will be described with reference to FIG. 1 as follows.

1A is a diagram of a normal state of charge of a battery, in which the voltage of a nickel-cadmium or nickel-hydrogen battery increases with charging time until the peak voltage is reached.

After the peak voltage is reached, the nickel-cadmium or nickel-hydrogen battery does not increase due to its unique phenomenon, but rather begins to decrease slightly. Detects-△ V of cadmium or nickel-hydrogen battery voltage and immediately stops fast charging or switches to charging by microcurrent.

That is, it is possible to know that the state of charge of the battery is full by detecting -ΔV generated after full charge due to the characteristics of the nickel-cadmium or nickel-hydrogen battery.

However, in the conventional battery full charge detection method as described above, the method using ΔV is charged at the beginning of charging as shown in the diagram shown in FIG. 1B when the nickel-cadmium or nickel-hydrogen battery is charged without using the battery for a long time. When ΔV is generated to stop the charging, and even when a phenomenon in which the battery voltage falls slowly in the middle of charging occurs, as shown in the diagram shown in FIG. 1C, -ΔV is generated to stop the charging in a substantially uncharged state. There was a problem that the charging of the battery is stopped.

In addition, even in the timer method of charging for a predetermined time, the difference in the charge amount is generated depending on the ambient temperature and the remaining battery charge, and even when the battery is installed in the charger, the battery is charged for a predetermined time regardless of the state of charge of the battery. .

In addition, the temperature detection method for controlling charging by detecting reaching a certain temperature also has a problem in that an error occurs due to the influence of the ambient temperature change and the exothermic temperature of the charger, which results in uncharging.

In addition, the method of detecting the change in the slope of the voltage rise is used in parallel with the method of using -ΔV, which causes a problem that the charging is stopped when the initial peak voltage or -ΔV occurs in the middle of the charging process. The temperature of the battery rises, which contributes to the shortening of the battery life.

The present invention has been made to solve the above-mentioned problems, stops the rapid charging of the battery by accurately detecting that the charge (slightly ahead of the voltage peak point) of about 75% to 90% at the time of charging is switched to the final charging An object of the present invention is to provide a full charge detection method of a rechargeable battery and a device thereof.

In addition, an object of the present invention is to prevent the rise of the battery life by preventing the temperature rise of the battery during charging.

1A is a state diagram of normal charging of a battery;

1B to C are diagrams showing state of charge when the battery is abnormal;

2 is a circuit diagram showing an embodiment of the present invention;

3a and b is a circuit diagram of the internal resistance measurement of the battery,

4A is a state diagram showing changes in charger supply voltage and battery terminal voltage when a battery is charged;

4B is a measurement waveform diagram of the charger supply voltage and the battery terminal voltage.

Explanation of symbols for main parts of the drawings

40: first memory and arithmetic device, 50: second memory and arithmetic device,

70: charging control unit, 80: charging unit,

BAT: rechargeable battery, e5: charger supply voltage,

e6: Battery terminal voltage, A / D1, A / D2: Analog / Digital converter,

Io: charging current.

The full charge detection method of the rechargeable battery of the present invention measures the terminal voltage of the battery being charged and the charger supply voltage at an appropriate period to detect the slope of the voltage difference (the slope of the increase in battery internal resistance) at the time when the voltage difference increases. Detecting the full charge state of the battery, the rate of change of the slope of the voltage difference from the time when the voltage difference between the battery supply voltage and the battery terminal voltage starts to increase when the charging current is intermittently supplied and charged. (ΔeD / Δt) is sensed to detect a time when the battery grows beyond the set value as a time when the battery reaches a full charge state.

In other words, as the voltage difference between the charger supply voltage and the battery terminal voltage increases rapidly, since the internal resistance of the battery rapidly increases and the supply voltage from the charger must be increased in proportion to the increase of the battery internal resistance in order to flow a constant charging current, the charger supply voltage and the battery This means that the difference in the terminal voltage is increased.

In addition, the full charge detection device of the rechargeable battery of the present invention, the analog / digital converter for measuring the charger supply voltage and the battery terminal voltage at different times and convert them into digital signals, respectively, and the charger output from the analog / digital converter A first memory and a calculation device for calculating a difference between a supply voltage and a battery terminal voltage, and a second memory for outputting a slope representing a change in battery internal resistance by calculating a signal output from the first memory and the calculation device as a time change rate And a fast charging signal when the input slope is lower than the set slope, and a signal for canceling the fast charging state when the input slope is lower than the preset slope by comparing the arithmetic unit and the slope output from the second memory and the arithmetic unit to the charging unit. It consists of a charge control unit.

In the rechargeable battery full charge detection device of the present invention, since the charging current is intermittently supplied to the battery at a ratio of a current supply time and a residual supply pause time of 7: 1, the battery terminal voltage and the charge current measured when the charge current is not supplied. When the charger supply voltage is supplied, the analog / digital converter converts the digital signal into a digital signal, respectively, and detects the slope of the voltage difference by the digital signal.

(Example)

Hereinafter, an embodiment of a full charge detection apparatus for a battery of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram of a battery charging apparatus including an embodiment of a full charge detection apparatus for a battery of the present invention, which detects whether a battery BAT is inserted into a charger and generates a charging signal and a reset signal, and whether the battery is present or not; In the initial battery check unit 20 and the measurement pulse generator 30 that measure the reset unit 10 and the voltage of the inserted battery BAT to determine whether there is an abnormality of the battery and output the signal. Analog / digital converters (A / D1) (A / D2) for measuring the charger supply voltage (e5) and the battery terminal voltage (e6) at different times by converting them into digital signals, respectively, and the analog / digital The first memory and the calculation device 40 for calculating the difference between the charger supply voltage (e5) and the battery terminal voltage (e6) output from the converter, and the signal output from the first memory and the calculation device divided by the time change rate to calculate My battery The second memory and the calculation device 50 outputting a slope indicating a change in the negative resistance and the temperature of the rechargeable battery BAT are measured with a dummyster NTC to detect an operation stop signal when the temperature exceeds the allowable charge range. When the output voltage is within the allowable charging temperature range, the voltage measuring unit 60 outputs the operation signal and the voltage generated at both ends of the resistor R5 by the charging current Io is compared with the set reference voltage. A current input unit 81 outputting a control signal to the charging unit 80 so that Io) flows, and a slope inputted by comparing the slope output from the second storage device 50 with a preset slope is lower than the set slope. The charging control unit 70 outputs a fast charging signal in the case of a fast charging signal, and a signal for canceling the rapid charging state in the case of a high charge to the charging unit 80, and charges according to the signals output from the charging control unit 70 and the current sensing unit 81. Remove the current Io For example, the charging unit 80 is configured to perform rapid charging or to switch to a final charging state or a trickle charging state.

The battery presence recognition and reset unit 10, the initial battery check unit 20, the analog / digital converter (A / D1) (A / D2) and the supply voltage (Vcc2) and the voltage divider (R2 ~ R4) and excessive When the zener diode for protection against input resistance (D2) and the capacitor (C) for smoothing action are connected in series and in parallel, a voltage of 5 volts or more is applied to R3 when the rechargeable battery is not inserted. Since the voltage is less than 4 volts, the whole device is reset and charging is performed.

As in the above apparatus, the charging unit 80 supplies a charging current Io to control a signal applied to the base terminal of the transistor Tr to charge a nickel-cadmium or nickel-hydrogen battery. It is the same as before.

Here, the diode D1 and the coil L are connected in parallel to the emitter terminal of the transistor Tr so that the charging current Io supplied to the rechargeable battery BAT is constantly supplied.

In addition, the charging unit 80 is a pulse width modulation (Pulse Width Modulation (PWM)) is applied, the period of the periodic pulse width modulated in accordance with the signal of the charging control unit 70 or the current sensing unit 81 and the current flows To adjust the charging current (Io) according to each state of charge.

When the battery BAT is inserted into the above device, the battery presence recognition and reset unit 10 detects this, resets the charging control unit 70 to prepare for the charging operation, and the first memory and the calculation unit 40. And the second memory and the computing device 50, etc. are reset.

When the fully charged battery BAT is inserted into the charger, ΔeD / Δt becomes large at the initial inspection time of FIG. 4A, so that the first memory and the computing device 40 and the second memory and the computing device 50 are increased. According to the input value of), it outputs a signal to release the fast charge state and in this case, switches to the trickle charge state.

On the other hand, when the battery BAT requiring rapid charging is inserted, the charging unit 80 supplies the charging current Io supplied to the battery BAT through the transistor Tr in response to a signal from the charging control unit 70. The battery is rapidly charged by controlling the battery, and when the full charge state is detected, the battery is switched to the finish charge state, and after a predetermined time, the battery is switched to the trickle charge state.

In this way, when the charging current is supplied to the battery and charged, as shown in FIG. Finishing charge is charging current (Io) × And trickle charge is charge current (Io) × The current flowing time is controlled to be a period of.

That is, the cycle at the time of supplying the charging current (Io) is trickle in the case of the rapid charging, for example, the charging current (Io) in the cycle of 28 seconds charger, 4 seconds rest period, the final charge of 8 seconds charger, 24 seconds rest period In the case of charging, it is supplied in a cycle of 1 second charger and 127 seconds of rest period.

As such, supplying the charging current Io intermittently is for increasing charging efficiency and reducing memory phenomenon.

When the battery BAT is normally charged, the charging control unit 70 recognizes the battery presence and reset and the initial battery check unit 20, the second memory and the computing device while the battery reaches a full charge state. The control unit 80 controls the charging unit 80 by detecting a change in the internal resistance of the battery by inputting a signal output from 50 to determine which mode, that is, the rapid charging state or the trickle charging state.

At this time, the method for measuring the internal resistance of the battery used in the full charge detection device of the battery of the embodiment of the present invention is largely classified into two types as shown in FIG.

In the method of measuring the initial voltage of the battery and dividing the difference from the voltage when a small load current flows, the measured voltage when the switch SW1 is opened and the measured voltage when the switch SW1 is closed When e2, the current flowing at this time i, the battery internal resistance r is as follows.

(But i should be as small as possible)

In addition, in a method of measuring a supply voltage at this time and a terminal voltage of the battery by flowing a current externally to the battery, the terminal voltage of the battery when the switch SW2 is opened is closed by a constant charge current by closing the switch SW2. When the measured voltage of the voltmeter (V) when e flows, and the current flowing at this time is i, the battery internal resistance r is as follows.

In the above two methods, the latter method is used in the present invention.

As described above, since the internal resistance change of the battery is represented by the difference between the charger supply voltage e5 and the battery terminal voltage e6 when a constant current flows, for example, as shown in FIG. 4B, for example, the charging current Io. At 26 seconds of the current supply time of 28 seconds, the charger supply voltage (e5) is measured by the analog / digital converter (A / D1) for 1 second, and during the current supply stop time of 4 seconds when the charging current (Io) does not flow. Measure the terminal voltage (e6) of the battery with an analog / digital converter (A / D2) for 1 second at the end.

The difference between the charger supply voltage e5 and the battery terminal voltage e6 measured by the analog / digital converters A / D1 (A / D2) is stored in the first memory and the computing device 40, and the second memory. And the operation device 50 calculates a difference between the charger supply voltage e5 and the battery terminal voltage e6, which are the output signals of the first memory and the operation device 40, as a time change rate to detect whether the slope suddenly changes.

As such, when the slope calculated by the second memory and the calculation device 50 exceeds the slope set in advance in the charge control unit 70, the charge control unit 70 indicates that the state of charge of the battery BAT is full. Judgment outputs the release signal of the fast charging state to the charging unit 80, the charging unit 80 stops the rapid charging by controlling the charging current (Io) in accordance with the signal through the final charging state and fine charging current (Io) Keeps the trickle charged.

Here, the current sensing unit 81 compares the control signal by comparing the voltage generated across the resistor R5 with the set reference voltage when the battery BAT is charged with the charging current Io controlled by the charging unit 80. By outputting to the charging unit 80, a constant charging current (Io) can be supplied.

As such, in addition to controlling the state of charge by the change of the internal resistance of the battery BAT, when the temperature of the battery is outside the charge allowable temperature range, the charge control unit 70 is controlled by a signal from the temperature measuring unit 60 which detects this. Stop charging

When the battery with the remaining capacity is inserted into the charger, the charger supply voltage e5 and the battery terminal voltage e6 are stored in the first memory and the computing device 40 and the second memory and the computing device 50 in the same manner as described above. The time to reach the point where the slope of the change in the internal resistance of the battery is calculated by the rate of change of time according to the time change rate depends on the remaining capacity of the battery.

In other words, when the battery has a large capacity, the time to reach the point where the slope of the internal resistance change rapidly rises is rapidly changed to trickle charging after the final charging in a short time after the battery is inserted into the charger. .

And, the less the remaining capacity of the battery, the longer the fast charge time.

The above-described progress of the charging state or occurrence of a problem during charging is displayed on the display unit 90 constituted by the light emitting diodes D3 and D4.

As described above, when the voltage difference between the charger supply voltage (e5) and the battery terminal voltage (e6) is measured at different times, it is determined that the battery is in a fully charged state when a sudden increase in the internal resistance change of the battery occurs. The method and apparatus for detecting the full charge state by changing the internal resistance of the all belong to the scope of the invention, of course.

The present invention as described above, by using a change in the battery internal resistance can stop the charging or switching to trickle charge due to the sudden-△ V phenomenon occurring in the uncharged state of the battery to prevent the complete charging is not made It can be charged for a wide range of battery capacity (300mA / h ~ 2500mA / h) without adjusting the charging current and there is almost no temperature rise of the battery because it does not generate heat during charging by switching from full charge to finish charge. It is effective to prevent shortening of the battery life.

In addition, since the battery is not affected by the temperature around the battery when the full charge is detected, the battery can be fully charged at all times without being charged or overcharged.

Claims (9)

Measuring the charger supply voltage and the charging battery terminal voltage at different times; calculating a slope of the battery internal resistance increase by calculating a difference in the measured voltage as a time change rate; The full charge detection method of a rechargeable battery, characterized in that for detecting the full charge state when the slope of the internal resistance rise is higher than the set slope compared to the set slope. 2. The full charge detection method for a rechargeable battery according to claim 1, wherein a current is supplied by a charger intermittently. The full charge detection method for a rechargeable battery according to claim 2, wherein the supply time and the supply pause time of the charging current are set to 7: 1. 4. The full charge detection method of a rechargeable battery according to claim 2 or 3, wherein the charger supply voltage is measured at the time of charging current supply, and the charge battery terminal voltage is measured at the time of stopping the charging current supply. A charging device for a rechargeable battery that senses a charging state of a rechargeable battery BAT charged by supplying a constant current and charges it to a maximum capacity, wherein the charger supply voltage e5 and the battery terminal voltage e6 are different from each other. And analog to digital converters (A / D1) (A / D2) for measuring and converting them into digital signals, respectively, and the charger supply voltage (e5) output from the analog / digital converters (A / D1) (A / D2) and The first memory and the calculation device 40 for calculating the difference between the battery terminal voltage e6 and the signal output from the first memory and the calculation device 40 are calculated by dividing the time change rate to indicate a change in the battery internal resistance. Comparing the slope output from the second memory and the calculation device 50 with a preset slope and outputting a slope, when the input slope is lower than the set slope, the fast charging signal is output; High class Charging of the battery full charge detecting device comprising: a charge control portion 70 for outputting a signal for releasing the charge in the charging section (80). 6. The full charge detection apparatus for a rechargeable battery according to claim 5, wherein the supply of current to said rechargeable battery (BAT) is intermittently performed. 7. The full charge detection apparatus for a rechargeable battery according to claim 6, wherein a current supply time and a current supply stop time of the rechargeable battery BAT are 7: 1. The analog / digital converter (A / D1) (A / D2) according to claim 6 or 7, wherein the charger supply voltage (e5) and the battery terminal voltage (e6) are respectively supplied at a current supply time and a current supply stop time. Full charge detection device for a rechargeable battery, characterized in that measured by. The full charge detection device for a rechargeable battery according to claim 5, wherein the charging control unit (70) controls the charging unit (80) for finishing charging and trickle charging in addition to rapid charging.