KR20050005925A - Charge control device of battery - Google Patents

Abstract

PURPOSE: A charge control device is provided to control the charge operation of a battery cell in a safe manner by detecting charge voltage and charge current directly from a battery cell in a battery pack. CONSTITUTION: A charge control device comprises a battery pack(60) and a charge control unit. The battery pack includes a battery cell(64), a voltage detection unit(62) for detecting charge voltage of the battery cell, and a current detection unit(66) for detecting charge current of the battery cell. The charge control unit controls the charge operation of the battery cell on the basis of the detection values of the voltage detection unit and the current detection unit for detecting voltage and current from the battery cell. The charge control unit includes a DC/DC switching portion(52) and a charge control portion(54).

Description

Charge control device of battery

The present invention relates to a charge control device for a battery, and more particularly, to a charge control device for a battery for controlling the charging of the battery by detecting the battery cell voltage / current.

Portable devices, such as laptop computers and PDAs, are supplied with commercial AC power using an adapter or with the power required by the product using a battery. Since these portable devices are mobile and portable, the weight, size and battery management of the main body are vital.

The battery used in the portable device is a rechargeable secondary battery. In recent years, the development of portable and wireless electronic products has been increasing, and the need for a secondary battery having high energy density has emerged for miniaturization and light weight of these products. In addition, as interest in environmental conservation increases, so does interest in environmentally friendly products.

In this respect, the lithium ion secondary battery satisfies the above requirements. The lithium ion battery has many advantages such as high energy density, high operating voltage, long life, and excellent storage capacity. Accordingly, lithium ion secondary batteries have been widely applied to portable devices such as personal computers, camcorders, portable telephones, CD players, and PDAs.

Next, a charging control apparatus for a battery according to the prior art will be described with reference to FIG. 1.

The conventional battery is configured in the form of a cell array inside the battery pack 13. The charger unit 17 for charging the battery inside the battery pack 13 is connected between the power input unit 1 for supplying charging power to the battery pack 13 and the battery pack 13. The charger unit 17 includes a DC / DC switching unit 3 for converting a power inputted through the power input unit 1 into a voltage and a current according to a battery charging power and outputting the battery pack 13. A current detector 11 for detecting a charging current of the battery through the current sensor 5, a voltage detector 9 for detecting a voltage of the battery pack 13, the current detector 11, and a voltage detector 9. Is provided with current and voltage information of the battery from the battery, and controls to perform constant current charging at a predetermined constant current value until the battery voltage reaches 4.2 V / cell voltage, and when the battery voltage reaches 4.2 V / cell voltage, And a charge control unit 7 for controlling the constant voltage charge to the output voltage of the charger unit 17 at 4.2 V / cell.

In addition, a connector unit 15 connecting the charger unit 17 and the battery pack 13 is provided between the charger unit 17 and the battery pack 13.

In the conventional battery charge control device having the above configuration, the charge voltage of the battery pack 13 is detected at the output of the charger unit 17 of the battery to control the charger unit 17. Accordingly, when the battery is being charged, a voltage drop occurs due to an impedance component from the output of the charger unit 17 to the input of the battery cell inside the battery pack 13, and the output of the charger unit 17 and the actual battery are generated. Voltage difference occurs between cells.

Between the output of the charger unit 17 and the battery cells in the battery pack 13, the connector unit 15 connecting the battery pack 13 and the charger unit 17, and the safety inside the battery pack 13 A protection circuit is provided. This is shown in FIG.

That is, as shown, between the charger unit 17 and the battery cells 27 in the battery pack 13, the connector 15, the fuse 19, the charge switching device (FET: 21), the discharge switching device (23), and there is a pattern impedance connecting the elements.

Due to these configurations, even though the output voltage of the charger unit 17 is 4.2V / cell, the actual battery cell 27 voltage inside the battery pack 13 is lower than 4.2V / cell. Therefore, when the charging voltage detected from the voltage detector 9 reaches 4.2V / cell, the charger unit 17 may not charge the battery controller 27 even though the actual battery cell 27 voltage does not reach 4.2V / cell. (7) switches from the constant current mode to the constant voltage mode to control the charging of the battery.

That is, as shown in FIG. 2A, when the charging voltage of the charger unit 17 reaches 4.2 V / cell, the output of the charger unit 17 switches from the constant current mode to the constant voltage mode under the control of the charging control unit 7. It is done. However, the battery cell voltage has not reached 4.2V / cell.

Therefore, when the actual battery cell 27 voltage becomes 4.2V / cell, the charging control unit 7 should be controlled in the constant voltage mode, but before the constant current charging time is shortened by changing from the constant current mode to the constant voltage mode. As the amount of current input to the battery pack 13 is small, the charging time becomes long.

In addition, the charging voltage of the battery is lowered due to a large error in the charging voltage due to the impedance component from the output of the charger unit 17 to the actual input of the battery cell 27, thereby reducing the charging capacity of the battery cell 27. .

In particular, as shown in FIG. 2B, the lithium ion battery can increase the amount of charge of the battery by controlling the charge so that the control of the charge voltage is not exceeded while accurately controlling the charge voltage to 4.2V. If the error is large, there is a risk of overcharging and the charging voltage cannot be increased. As a result, the battery charge can only be lowered.

As described above, in a lithium ion battery, the charge voltage level of the battery immediately indicates the charge capacity of the battery. Therefore, when the charge voltage of the battery is less than 0.1 V / cell at 4.2 V / cell, the total capacity of the battery is about 10%. Since the degree is reduced, it is important to control the charging voltage so as not to exceed the 4.2V / cell voltage while increasing the charge voltage to 4.2V / cell as much as possible. However, precision control is difficult due to the error due to the impedance component, and the charge capacity is low because the battery charge voltage is low.

As described above, the charging of the battery is controlled by detecting the charging voltage and the current of the battery from the output of the charger unit 17 at the time of charging the battery. Therefore, it was not the charge control by the charge voltage and the current of the actual battery. Therefore, due to the impedance between the output of the charger unit 17 and the battery cell 27 that is actually charged, due to the voltage difference between the output of the charger unit 17 and the battery cell 27 is the output voltage of the charger unit 17 Even when the battery cell 27 does not reach 4.2V / cell even when the battery cell 27 reaches the 4.2V / cell and is switched to the constant voltage charging mode, the charging time is long because the constant current charging time is short.

In addition, an error between the output of the charger unit 17 and the battery cell 27 being actually charged causes an error in the charging voltage of the battery cell 27, and this error is caused by the charge voltage control of the battery cell 27. Decreases precision. Therefore, while the charge voltage of the battery cell is charged at a voltage lower than the full charge voltage (4.2V / cell), the charge amount is reduced, due to this has a problem that the battery usage time is shortened.

Accordingly, an object of the present invention is to provide a charge control apparatus for a battery that can safely control charging of a battery cell by detecting a charge voltage and a charge current directly from the battery cell inside the battery pack.

Another object of the present invention is to provide a charge control apparatus for a battery capable of detecting a charge voltage and a charge current directly from a battery cell inside a battery pack to increase and control the charge voltage of the battery cell and shorten the charging time.

Still another object of the present invention is to detect the charge voltage and the charge current directly from the battery cell inside the battery pack to precisely control the battery cell charge voltage, increase the charge rate of the battery charge control device of the battery can be extended In providing.

1 is a configuration diagram of a charging control device for a battery according to the prior art;

2A is an output waveform diagram illustrating a difference between an output voltage of a charger unit and a charge voltage of a battery cell according to the prior art;

2b illustrates a typical battery voltage operating region;

3 is a configuration diagram of various electrical elements provided between a general charger unit and a battery pack;

4 is a configuration diagram of a battery charge control device according to the present invention;

5 is a detailed circuit diagram of a battery charge control apparatus according to the present invention;

Figure 6 is an output waveform diagram showing the difference between the output voltage of the charger unit and the battery cell charging voltage according to the present invention.

Explanation of symbols on the main parts of the drawings

50: power input unit 52: DC / DC switching unit

54: charge control unit 56: charger unit

58, 68, 70: connector 60: battery pack

62: voltage detector 64: battery cell

66: current detector

Charge control device for a battery according to the present invention for achieving the above object, the battery cell; A voltage detector detecting a charging voltage of the battery cell; A battery pack having a current detector for detecting a charging current of the battery cell, and charging control means for controlling charging of the battery cell based on detection values of the voltage detector and the current detector for detecting voltage and current from the battery cell; It is configured to include.

The charging control means may include: DC / DC switching means for converting a power inputted to the battery cell into a voltage and a current according to a battery charging power and outputting the converted power; And a charging control section for controlling the switching operation of the DC / DC switching means based on the detected values of the voltage detecting section and the current detecting section.

The voltage detector includes a voltage divider connected to one side of the battery cell; And a comparator for outputting the voltage distribution means as the first input and outputting the difference between the two signals with the reference voltage as the second input.

The current detector is characterized in that for using a current / voltage converter.

Hereinafter, a charging control apparatus of a battery according to the present invention will be described in detail with reference to the accompanying drawings.

The battery charge control device of the present invention is configured to detect a charge current and a charge voltage from a battery cell inside a battery pack. To this end, the present invention includes a charge control device as shown in FIG.

As shown in the drawing, the battery charge control apparatus of the present invention includes a power input unit 50 for supplying battery charging power and a charger unit 56 between the battery pack 60.

The charger unit 56 may include a DC / DC switching unit 52 for converting power input from the power input unit 50 to a voltage and a current necessary for charging a battery, and inside the battery pack 60. By using the detected charging current and the charging voltage as the battery control information, the constant current charging is controlled to a set constant current value until the battery voltage reaches 4.2V / cell voltage, and the battery voltage reaches 4.2V / cell voltage. If the battery voltage is a constant voltage control to 4.2V / cell voltage is configured to include a charge control unit 54.

As shown in FIG. 5, the switching unit 52 includes a switching element (FET) that opens and closes a power supply path so that power output from the power input unit 50 can be supplied to the battery pack 60. A diode (D) connected between the output terminal of the switching device (FET) and the ground, an inductor (I) connected to the output terminal of the switching device (FET), and a rear end of the inductor (I) and ground. The capacitor C is comprised.

Between the charger unit 56 and the battery pack 60, connectors 58, 68, and 70 for electrically connecting the charger unit 56 and the battery pack 60 are provided.

The battery pack 60 includes a battery cell 64 configured by connecting the plurality of cells in series or in parallel, a current detector 66 detecting a current of the battery cell 64, and the battery cell 64. It is configured to include a voltage detecting unit 62 for detecting the voltage of). The charging current and the charging voltage detected through the current detector 66 and the voltage detector 62 are input to the charge control unit 54 of the charger unit 56 through the connectors 68 and 70.

As illustrated in FIG. 5, the voltage detector 62 uses the resistors R1 and R2 connected in series to one side of the battery cell 64 and the divided voltages of the resistors R1 and R2 as inverting terminals. The reference voltage source V1 is connected to an input comparator OP1 and a non-inverting terminal of the comparator OP1. One side of the resistor R2 is configured to be connected to ground. The comparator OP1 is configured of an op amp.

As illustrated in FIG. 5, the current detector 66 connects a resistor R3 between the battery cell 64 and the ground and connects both terminals of the resistor R3 to the inverting terminal of the comparator OP2. And non-inverting terminals, respectively. The comparator OP2 is configured of an op amp. The current detector 66 may use a current / voltage converter.

Next will be described the operation of the charge control device of the battery according to the present invention having the above configuration.

As shown in FIG. 2B, the lithium ion battery can increase the battery charge amount as the control of the charging voltage is more precise (control close to 4.2 V / cell). In addition, lithium ion batteries need to prevent overcharge and overdischarge in order to protect them from safety hazards. However, when the impedance error between the battery and the charger is large, the charging voltage cannot be increased due to the fear of overcharging, and the battery charging amount can only be lowered due to this problem.

However, in the present invention, the charge voltage and the charge current are detected directly from the battery cell 64. That is, as illustrated in FIGS. 4 and 5, the voltage detector 62 and the current detector 66 connected to both ends of the battery cell 64 directly detect the charge voltage and the charge current of the battery cell 64. do.

The voltage detector 62 divides the charging voltage of the battery cell 64 by the resistors R1 and R2 and inputs the same to the comparator OP1, and the comparator OP1 is detected by comparison with a reference voltage. Generate square wave pulses for charging voltage. In addition, the current detector 66 detects the charging current of the battery cell 64 through the resistor R3. That is, a value corresponding to the charging current is detected by the comparator OP2 as a voltage value across the resistor R3, and a square wave pulse corresponding to the charging current is generated.

The square wave pulse corresponding to the charging voltage detected by the voltage detector 62 is connected to the charge control unit 54 of the charger unit 56 through a connector 68 connecting the battery pack 60 and the charger unit 56. It is input. In addition, the square wave pulse corresponding to the charging current detected by the current detector 66, the charging control unit 54 of the charger unit 56 through the connector 70 connecting the battery pack 60 and the charger unit 56. Is entered.

The charging control unit 54 controls the charging of the battery pack 60 based on the detected charging voltage and charging current. That is, during the charging operation of the battery, the charging of the battery cell 64 is controlled with a constant current set until the charging voltage detected from the battery cell 64 reaches 4.2 V / cell. At this time, the charging current detected through the current detecting unit 66 is fed back, and the control is performed such that constant current charging is performed.

When the charging voltage detected from the battery cell 64 reaches 4.2 V / cell, the charging control unit 54 is charged from the voltage detecting unit 62 so that the charging voltage can maintain 4.2 V / cell. Receives feedback and controls constant voltage charge.

With this control, the present invention can control the charge voltage of the battery cell 64 high, thereby increasing the charge amount. That is, as shown in FIG. 6, in the present invention, when the voltage of the battery cell 64 reaches 4.2 V / cell, the control is such that the switching from the constant current mode to the constant voltage mode is performed. At this time, the output voltage of the charger unit 56 is higher than 4.2V / cell, thus the constant current section is longer than in the prior art. In addition, since the constant current charging time T3 is longer than that of the conventional T1, the total charging time T4 is shorter than that of the conventional T2.

As described above, the charging control apparatus for a battery according to the present invention detects the charging voltage and the charging current directly from the battery cell when the battery is charged, and controls the charging of the battery cell using the detected value. It has its features. To this end, the present invention comprises a current detector for detecting the charge current of the battery cell and a voltage detector for detecting the charge voltage of the battery cell, the charge current and the charge voltage detected by the current detector and the voltage detector It is configured to be delivered to the charger unit for controlling the charging of the battery. According to the above control, the present invention suppresses the impedance error existing between the output voltage of the charger unit and the battery cell, thereby shortening the total charging time and increasing the charging capacity while increasing the constant current charging time.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

The charging control device of the battery according to the present invention described above can obtain the following effects.

First, the present invention has the effect of shortening the charging time as the constant current charging time is longer by controlling the charging voltage higher than in the prior art that lowered the battery charging voltage in consideration of the amount of voltage drop between the output of the charger and the actual battery cell. Get

Second, the present invention enables precise control of the battery charging voltage by controlling the charging of the battery by detecting the charging voltage and the charging current from the actual battery cell. Therefore, while the error of the charging voltage is suppressed, the charging rate of the battery fully charged battery is increased, and at the same time, the battery discharge time is increased by increasing the charging capacity.

Third, the present invention can control the charging of the battery safely by detecting the battery voltage and current being actually charged from the battery cell to control the charging of the battery.

Claims (4)

A battery cell; A voltage detector detecting a charging voltage of the battery cell; A battery pack having a current detector detecting a charging current of the battery cell; And charge control means for controlling charging of the battery cell based on a voltage detector and a voltage detector for detecting voltage and current from the battery cell. The method of claim 1, The charging control means may include: DC / DC switching means for converting a power inputted to the battery cell into a voltage and a current according to a battery charging power and outputting the converted power; And a charging control unit for controlling the switching operation of the DC / DC switching means based on the detected values of the voltage detection unit and the current detection unit. The method of claim 1, The voltage detector includes a voltage divider connected to one side of the battery cell; And a comparator for outputting the voltage distribution means as a first input and a reference voltage as a second input to output a difference between the two signals. The method of claim 1, And the current detector uses a current / voltage converter.