KR20000019007A - Charger for lithium-ion battery and nickel-hydrogen battery - Google Patents

Abstract

PURPOSE: A double use charger of a lithium-ion battery and a nickel-hydrogen battery is provided to charge two kinds of batteries with one charger by automatically discriminating a kind of an inserted battery and proceeding a charging process according to characteristics of the kind. CONSTITUTION: A double use charger for a lithium-ion battery and a nickel-hydrogen battery in one comprises a unit for converting common alternative current power into direct current power, outputting battery supply voltage by modulating and controlling the converted direct current power according to an amount of a detected error, and charging the outputted supply voltage to an inserted battery; a battery discriminator; a sensing resister; a controller for controlling static current charging operation; and an error detector.

Description

How to charge a lithium ion battery and a nickel metal hydride battery charger

The present invention relates to a charging method of a lithium ion battery (Li-ion battery) and a nickel-hydrogen battery (Ni-H) combined charger and a combined charger.

In recent years, as mobile phones such as cellular phones and cellular devices such as handheld PCs have increased in popularity, the use of batteries as a power supply for portable mobile products has been rapidly increasing.

There are many types of such batteries, and there are two types of disposable batteries and rechargeable batteries that can be recharged and reused (hereinafter referred to as "batteries"). And Ni-MH or Ni-Cd rechargeable batteries.

Therefore, lithium-ion chargers and nickel-hydrogen chargers are distinguished and designed for safe charging according to battery characteristics of rechargeable batteries.

Accordingly, since the user uses only a limited battery in the portable device, the charger also needs to separately use only a charger designed according to the battery.

The present invention is intended to provide a charger capable of charging both a lithium ion battery and a nickel hydride battery regardless of the type of battery for the convenience of the user.

First, FIG. 1 is a diagram illustrating characteristics of a lithium ion battery and a nickel hydride battery. Referring to FIG. 1, the characteristics of a lithium ion battery and a nickel hydride battery used in a portable device will be described.

The battery voltage of a lithium ion battery is 4.2 [V] per cell, and the internal resistance of the battery is about 0.1 [ohm]. There is a problem with stability.

Therefore, the lithium ion charger necessarily includes an overvoltage application prevention circuit, and prevents the overvoltage from being applied to the battery by precise control.

On the other hand, in the case of a nickel hydride battery, the battery voltage is 1.2 [V] per cell and the internal resistance is extremely low, about 0.02 [ohm], so that a large current charge / discharge is possible.

Therefore, when looking at the charging characteristics of the lithium ion battery, the overvoltage should not be applied. Therefore, as shown in FIG. 2A, in the initial stage of charging, a large current flows into the battery at a constant current to perform rapid charging. In order to reduce the charging current, only a small current flows into the battery.

Because of this, the charging time of the lithium ion battery can not only be extremely long.

However, as shown in FIG. 2B, the Ni-MH battery is not sensitive to overvoltage, so that it can be rapidly charged with a large current by the charging current set at the time of charging, but the 100% rechargeable battery capacity is fully charged. It is difficult to determine whether or not.

3 is a block diagram illustrating a charger configuration of a lithium ion battery, and FIG. 4 is a block diagram illustrating a charger configuration of a nickel hydride battery. Referring to FIGS. 3 and 4, the charger configuration of each battery is as follows.

The commercial power (AC 110V / 220V) supplied through the AC / DC converter 1 is converted into a DC voltage (DC), and the primary side of the transformer 3 is controlled by the PWM (Pulse Width Modulation) control unit 2. Is supplied.

The transformer 3 induces the DC voltage supplied to the primary side to the secondary side to transfer the supplied voltage.

At this time, an error detection unit 4 is configured in the secondary output voltage of the transformer 3, and detects the voltage induced in the secondary side of the transformer 3 to control the PWM through the feedback unit 5. By feeding back to (2), the PWM control unit 2 controls the voltage supplied to the primary side of the transformer 3 so that a constant voltage or current can be supplied through the transformer (3).

The voltage supplied in this way is supplied to the lithium ion battery according to the switching of the switch unit 6 to perform charging. In this case, the control unit 7 detects the battery voltage to control the charging process and to fully charge the switch unit 6. To control the end of charging,

The control unit 7 controls the constant current / constant voltage switching unit 8 in accordance with the battery voltage. As a result, the constant current / constant voltage switching unit 8 controls the switch unit 6 to control the constant current as described above. Allow constant voltage control.

Then, the battery voltage increases when the constant voltage is applied or detected, or by detecting the amount of current input to the battery to determine whether or not full charge.

Meanwhile, as shown in FIG. 4, the Ni-MH charger also has the AC / DC converter 11, the PWM controller 12, the transformer 13, the error detector 14, and the feedback unit as in the lithium ion charger. Through 15 to supply a constant voltage or current to the switch unit 16 at all times.

However, the nickel hydride charger performs charging of the battery while controlling the current to be set in the constant current setting unit 18 to flow through the constant current detector 19.

In addition, whether or not the end of the full charge is to determine the full charge by the detection of -ΔV in the control unit 17 or by the detection of dT / dt using the phenomenon that the temperature of the battery rapidly rises immediately after the full charge.

According to the characteristics of the battery as described above, the configuration of the charger as described above can not only be designed differently, the user should select and use the charger according to the battery.

The present invention is to share the charging circuit according to the characteristics of the lithium ion battery and the charging circuit according to the characteristics of the nickel-metal hydride battery, and to detect the battery by detecting the voltage of the battery to be installed to charge, the charging according to the characteristics of the determined battery By making this possible, two types of batteries can be charged with a single charger.

1 is a diagram showing the characteristics of a lithium ion battery (Li-ion battery) and a nickel-hydrogen battery (Ni-H battery).

2A is a waveform diagram of a battery voltage and a charging current with time for showing a charging process of a lithium ion battery.

Figure 2b is a waveform diagram of the battery voltage and charging current over time to show the charging process of the nickel hydride battery.

3 is a block diagram showing a charger configuration of a typical lithium ion battery.

4 is a block diagram showing a charger configuration of a typical nickel-metal hydride battery.

5 is a block diagram showing the configuration of a lithium ion battery and a nickel hydride battery charger according to the present invention;

6 is a block diagram showing a detailed circuit configuration of an error detection unit in the present invention.

Figure 7 is a flow chart showing the charging operation of the lithium ion battery and nickel hydride battery charger according to the present invention.

8 is a waveform diagram for each charging section for showing a charging control process of a lithium ion battery according to the operational amplifier output level of the error detector.

9 is a waveform diagram for each charging section for showing a charging control process of the nickel hydride battery according to the operational amplifier output level of the error detection unit in the present invention.

The present invention converts a commercial AC power source into a DC DC power source, outputs a battery supply voltage by PWM modulation control of the converted DC DC power source according to the detected error detection amount, and charges the battery into the inserted battery. In the battery charger comprising a means for,

Battery discrimination means for detecting the battery type by detecting the voltage of the inserted battery, sensing resistance means for detecting the charging current flowing through the battery, and error detection means for controlling the constant current / constant voltage or Control means for executing and controlling the constant current charging operation; and error detecting means for feeding back the detected voltage correction amount to the PWM control means through the feedback means so as to flow the constant voltage or the constant current under the control of the control means. Features,

The error detecting means includes: a constant voltage controller for detecting a DC output voltage and determining a DC output voltage correction amount of the PWM control means for controlling the constant voltage;

And a constant current controller for determining a DC output voltage correction amount of the PWM control means for the constant current control according to the charging current detected by the sensing resistor means.

The constant voltage controller and the constant current controller are characterized in that the output level is determined according to the control of the control means, the PWM control means characterized in that to determine the DC output voltage control by selecting a low output level.

The charging method of the combined charger of the present invention by such a device,

Fixing the DC output voltage to allow constant voltage control during initial operation, and then determining the type of battery without a current flowing in the battery;

Supplying a DC output voltage to the battery by turning on / off the charging start / end switch means, and determining the type of the battery in the state where the charging current is present in the battery;

Performing a charging operation of a constant voltage / constant current or a constant current by adjusting a DC output voltage supplied to the battery according to characteristics of the type of battery determined in the above process;

The procedure of performing the process to end the charging process by determining whether or not full charge according to the characteristics of the type of battery determined in the above process.

FIG. 5 is a block diagram showing the configuration of the lithium ion battery and the nickel hydride battery charger according to the present invention. Referring to FIG.

AC / DC converter 101 for converting commercial power (AC 110V / 220V) into a DC voltage, the PWM control unit 102 for controlling the DC-converted voltage, and the control of the PWM control unit 102 to the primary side The transformer 103 which induces and outputs the applied DC voltage to the secondary side, and monitors the voltage output from the transformer 103 to detect an error and feed it back to the PWM control unit 102 through the feedback unit 105 at all times. An error detector 104 for supplying a constant voltage or current, a switch 106 for switching the secondary output voltage of the transformer 103 to charge the battery 107, and an initial battery 107 The battery discrimination unit 108 for detecting a voltage to determine the type of battery, the sensing resistor unit 109 for detecting the amount of current flowing through the battery 107, and the battery discriminated through the battery determination unit 108. The error detection unit 104 is controlled according to the type so that the constant current / constant voltage or the constant Flow and to control the charging process, by detecting the current flowing through the sense resistor 109 to determine whether or not the maximum charge consists of microcomputer 110 to determine if end-of-charge.

The error detector 104 includes a constant voltage controller 104a and a constant current controller 104b, as shown in FIG.

The constant voltage controller 104a is switched and controlled under the control of the voltage divider resistors R1 and R2 for setting the level to a constant voltage (4.2V) and the microcomputer 110 for overvoltage protection of the lithium ion battery. ) Switch SW1 to prevent the risk of overvoltage of the battery and the danger of high current application, so that the voltage can be selected as a voltage drop resistor to lower the voltage level supplied to the battery, and the operational amplifier OP1 for constant voltage control. ),

The constant current controller 104b is switched under the control of the constant current control operational amplifier OP2, the voltage divider resistors R4 to R7 of the voltage across the sensing resistor unit 109, and the microcomputer 110. And a switch SW2 for selecting the resistor R5 for adjusting the output level of the OP2 and a switch SW3 for selecting the resistor R6,

The outputs of the operational amplifiers OP1 and OP2 are applied to the PWM control unit 102 through the feedback unit 105 through diodes D1 and D2 connected in opposite directions, and the PWM control unit 102 outputs the lower one of the two outputs. The power supply is controlled according to the output of the operational amplifier OP1 or OP2 having the output level.

Reference numerals C1 and C2 are capacitors.

According to the present invention having such a configuration, the constant voltage controller 104a and the constant current controller 104b included in the error detector 104 are controlled according to the characteristics of the battery 107 by the miter 110 according to the type of battery. Characterized in that it is possible to adjust the voltage and current supplied to the (107),

First, the commercial power of 110V / 220V is converted into a DC voltage through the AC / DC converter 101, and the converted DC voltage is induced and output to the secondary side through the transformer 103.

At this time, the error detection unit 104 detects an output DC voltage, detects an error so that a constant voltage is always output, and feeds it back to the PWM control unit 102 through the feedback unit 105, and the PWM control unit 102. In this case, the DC voltage applied to the transformer 103 is controlled according to the detected error amount.

When a constant voltage is output to the secondary side of the transformer 103 according to such an operation, the type of the battery 107 inserted into the microcomputer 110 through the battery discriminating unit 108 with the switch unit 106 turned off. Will be determined.

Here, since the battery voltage of the lithium ion battery is 4.2 [V] / 1 cell and the nickel hydride battery is 1.2 [V] / 1 cell, the microcomputer 110 can easily determine whether the rechargeable battery is a lithium ion battery or a nickel hydrogen battery. It becomes possible.

As described above, when the microcomputer 110 determines the type of the battery 107, the error detection unit 104 is controlled to control the secondary output voltage of the transformer 103 to be fixed to 4.2 [V], and then the switch. The unit 106 is turned on to supply the voltage to the battery 107 to determine the type of the battery 107 once again.

This is to prevent the battery 107 from being completely discharged, so that the battery voltage is not detected or the battery voltage of the lithium ion battery is extremely low, which may be incorrectly determined as a nickel hydride battery.

When 4.2 [V], which is the maximum value for preventing overvoltage of the lithium ion battery, is supplied to the battery 107 as described above, the battery voltage is increased, so that the lithium ion battery increases to 3.6 [V]. In the case of a nickel hydride battery, the battery voltage is restored to 1.2 [V].

If it is determined as a lithium ion battery through such a trial process, the microcomputer 110 controls the error detector 104 again to switch unit 106 → battery 107 → sensing resistor unit 109 → error detector 104. ) To supply a constant current to the battery 107 through.

At this time, while the microcomputer 110 supplies a constant current to the battery 107 as described above, while monitoring the battery voltage, the voltage supplied to the battery 107 is also monitored.

After a certain charging time, the supply voltage continues to rise in order to flow a constant current. At this time, when the supply voltage reaches 4.2 [V], the microcomputer 110 controls the error detector 104 to control the supply voltage. It is fixed at 4.2 [V].

This is the moment when the charging process of the lithium ion battery is changed from the constant current control process to the constant voltage control process.

The microcomputer 110 performs charging of the battery 107 through the constant voltage section as described above, continuously monitors the increase of the battery voltage, and senses the amount of current flowing in the battery 107 through the sensing resistor unit 109. do.

Then, when the moment when there is almost no amount of current flowing through the battery 107, that is, when the battery voltage and the supply voltage become the same, it is determined that the charge of the battery 107 is fully charged and the switch unit 106 is turned off. Switching is made to end charging.

On the other hand, if it is determined as a nickel-metal hydride battery, the microcomputer 110 controls the error detection unit 104 to generate a constant current through the switch unit 106 → battery 107 → sensing resistor unit 109 → error detection unit 104. To 107.

As described above, the microcomputer 110 controls the error detector 104 to supply a constant current to the battery 107, and detects an increase in battery voltage or a temperature increase of the battery to detect a full charge of the nickel hydride battery. The switch unit 106 is switched off to terminate charging of the nickel hydride battery.

7 is a flowchart illustrating an operation process of the present invention as described above.

In the charging process according to the operation as described above, the operation of the error detector 104 for performing constant current / constant voltage charging of a lithium ion battery and constant current charging of a nickel hydride battery will be described with reference to FIG. 6. As follows.

The error detector 104 includes an operational amplifier OP1 for constant voltage control and a constant voltage operational amplifier OP2 for constant current control, and includes an operational amplifier OP1 having a lower output value among the two operational amplifiers OP1 and OP2. The PWM controller 105 operates according to the output of the OP2).

The initial operation voltage is fixed to a constant voltage of 4.2 [V] to determine the battery 107,

The 4.2 [V] is the over-protection maximum voltage value of the lithium ion battery, and sets the resistance values of the resistors R1 and R2 so that the voltage can be fixed. Therefore, the output of the constant voltage control operational amplifier OP1 is low. (low).

At this time, since the switch unit 106 is turned off, no current flows into the battery 107, so that the output of the constant current control operational amplifier OP2 becomes high due to the resistors R4 and R7. The output level of the constant current control operational amplifier OP2 has a higher value than the output of the control operational amplifier OP1.

Therefore, as described above, the output voltage is fixed to 4.2 [V] before the determination of the battery is completed, and the PWM control unit 102 is operated by the output of the constant voltage control operational amplifier OP1.

Subsequently, when the type of the battery 107 is determined, the microcomputer 110 performs charging by turning on the switch unit 106.

In this case, when the inserted battery 107 is determined to be a lithium ion battery, when a current flows through the battery 107, a voltage drop occurs across the sensing resistor unit 109.

As such, the amount of voltage drop generated across the sensing resistor unit 109 is

Voltage drop = charge current (I-charge) × sensing resistance,

It can be represented as

When the voltage drop occurs as described above, the operational amplifier OP2 of the constant current controller 104b starts to operate and is lower than the output of the operational amplifier OP1 of the constant voltage controller 104a as shown in FIG. 8. In this state, the PWM controller 102 is operated by the output of the constant current control operational amplifier OP2.

In this case, since the constant current control operational amplifier OP2 is sensitively reflected on the output according to the amount of current (I-charge) charged in the battery, when the lithium ion battery is charged and the battery voltage rises, the incoming charging current decreases. Therefore, the PWM control unit 102 compensates this by reflecting this on the output of the operational amplifier OP2 so as to increase the output voltage so that it can be charged with a constant current.

While charging the battery 107 with a constant current through the operation as described above, when the battery voltage reaches about 4.2 [V] in the microcomputer 110, the switch SW2 is turned on so that the resistor R5 is connected to the circuit in FIG. 8. As shown, the output of the constant current operational amplifier OP2 is set higher than the output of the constant voltage operational amplifier OP1.

Then, after the switch SW2 is turned on, the operation of the PWM controller 102 controls the output voltage according to the output of the constant voltage operational amplifier OP1.

That is, at this time, the lithium ion battery is charged through the switch unit 106 → battery 107 → sensing resistor unit 109 at a constant voltage of 4.2 [V].

On the other hand, when the type of battery 107 is determined to be a nickel hydride battery,

In the microcomputer 110, the switch SW1 is turned on to lower the output voltage level by the resistor R3.

The nickel hydride battery has a battery voltage of 1.2 [V] / cell, which is considerably lower than that of a lithium ion battery, and its internal resistance is also about 0.02 [ohm]. Even though the secondary output voltage is less than 3 [V] (; 4A x 0.02 ohm + voltage drop) even when the voltage drop of the switch unit 106 is taken into consideration, the risk and high current of the over-voltage of the battery are applied in the case of a nickel-hydride battery. This is to set the output voltage to a slightly lower voltage in consideration of the danger of time.

After that, in the microcomputer 110, the switch SW3 is turned on to connect the resistor R6. As shown in FIG. 9, the constant voltage operational amplifier OP1 is formed by the resistors R4, R6, and R7. The output of the constant current operational amplifier OP2 has a lower value than the output.

Therefore, the PWM control unit 102 is to charge the nickel hydride battery with a constant current by the output of the constant current control operational amplifier OP2.

As described above, by automatically determining the type of battery to be inserted and charging according to the characteristics according to the type of the battery, the two different types of batteries can be charged by one charger. There is an effect that can promote the convenience and economy of the user.

Claims (4)

Means for converting a commercial AC power source to a DC DC power source, outputting a battery supply voltage by PWM modulation control of the converted DC DC power source according to the detected error detection amount, and charging control of the output battery supply voltage to the inserted battery. In the battery charger including: Battery discrimination means for detecting the battery type by detecting the voltage of the inserted battery, sensing resistance means for detecting the charging current flowing through the battery, and error detection means for controlling the constant current / constant voltage or Control means for executing and controlling the constant current charging operation; and error detecting means for feeding back the detected voltage correction amount to the PWM control means through the feedback means so as to flow the constant voltage or the constant current under the control of the control means. A lithium ion battery and a nickel metal hydride battery charger characterized by the above-mentioned. 2. The apparatus of claim 1, wherein the error detecting means includes: a constant voltage controller configured to detect a DC output voltage and determine a DC output voltage correction amount of the PWM control means for controlling the constant voltage; And a constant current controller for determining a DC output voltage correction amount of the PWM control means for the constant current control according to the charging current detected by the sensing resistor means. The constant voltage control unit and the constant current control unit, the output level is determined according to the control of the control means, the PWM control means to select the low output level to determine the DC output voltage control, characterized in that for both lithium ion battery and nickel hydrogen battery charger. The method of claim 2, wherein the constant voltage control unit is a voltage divider for lowering the voltage level to be supplied to the battery is controlled by the voltage divider resistor for setting the level to a predetermined voltage for overvoltage protection of the lithium ion battery, and the control means The output level is determined in accordance with a switch for allowing the resistance of the battery to be selected to prevent the risk of overvoltage of the battery and the risk of application of a large current, and the DC output voltage input by the voltage divider and the operation of the switch. It consists of operational amplifier for constant voltage control, The constant current control unit includes a constant current control operational amplifier whose output level is determined according to the voltage across the sensing resistor unit, and a voltage divider for adjusting the output level of the constant current control operational amplifier by dividing the voltage across the sensing resistor unit. And a switch for switching a control for controlling the output current of the constant current control operational amplifier for controlling the constant current by switching on during the constant current control after the constant voltage control of the lithium ion battery. And a switch configured to select a resistance to adjust the output level of the operational amplifier for constant current control of the nickel hydride battery. Fixing the DC output voltage to enable constant voltage control during initial operation, and then determining the type of battery without a current flowing in the battery; Supplying a DC output voltage to the battery by turning on / off the charging start / end switch means, and determining the type of the battery in the state where the charging current is present in the battery; Performing a charging operation of a constant voltage / constant current or a constant current by adjusting a DC output voltage supplied to the battery according to characteristics of the type of battery determined in the above process; The charging method of a lithium ion battery and a nickel-metal hydride battery charger characterized in that it has a procedure of determining whether or not the full charge according to the characteristics of the type of battery determined in the above process to end the charging process.