JPH04281340A - Battery charge controller - Google Patents

Abstract

PURPOSE:To prevent overcharge in a tapered charge region and to prolong the lifetime of a battery by providing an inner pressure sensor for battery and a comparator for comparing the battery voltage with a reference voltage in a voltage sensor. CONSTITUTION:When the charge operation proceeds and the terminal voltage of battery exceeds an external reference voltage 13, a comparator 12 functions to output a tapered charge signal 6A which is then delivered, as a control signal, to a charge section 3. The charge section 3 controls the charge current of a battery 4 so that the terminal voltage thereof drops below the reference voltage 13. Inner voltage of the cell in the battery 4 temporarily drops and then increases again as the time elapses and when it exceeds a preset level, a cell inner voltage sensor 2 functions to output a charge current control signal. When the inner voltage tapered charge signal is being applied, the charge section 3 decreases the charge current and lowers the cell inner voltage below a predetermined level.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a battery charging control device, and in particular, it is used for batteries used in artificial satellites, etc., which are charged from solar cells, and when the battery is repeatedly discharged to a load. The present invention relates to a battery charging control device for charging.

0002

BACKGROUND OF THE INVENTION Generally, as a method for controlling battery charging, a charging amount control method is used, that is, controlling the charging amount so that the charging amount/discharging amount is a constant ratio of usually about 1.05 to 1.2. There is a method. Another method is a constant current constant voltage control method (for example, a taper charging method) using charging voltage detection as an approximate charge amount control method.

[0003] As shown in the block diagram of FIG. 3, a battery charging control device that implements a conventional power failure current constant voltage control system includes a power source 10 such as a solar cell, a charging section 3 that controls the charging current, and a charging section 3 that controls the charging current. A load 9 represented by a battery 4, a voltage sensor 11 for detecting battery charging pressure, a communication device, etc.
, a discharge diode 8 that forms a discharge path from the battery 4 to the load 9, and a current sensor 7 that detects charging and discharging current, outputs a current control signal, and applies it to the charging section 3.

The operation of such a conventional example is shown in FIGS.
This will be explained with reference to the characteristic diagrams of general battery charging current shown in b) and (c). First, the state of the full charging area A shown in FIGS. 4(a) and 4(b) will be explained. The output from the power source 10 is supplied to the battery 4 with the charging flow controlled by the charging section 3 . A current sensor 7 is connected between the battery 4 and the power source 10.
are inserted in series. When charging is started and the terminal voltage of the battery 4 is below a preset value, the current sensor 7 monitors the charging current and discharging current of the battery 4, and when the battery 4 is in the charging state, the charging current When the current exceeds a predetermined current value, this current sensor 7 outputs a control signal to the charging unit 3, and the battery 4 is connected to the power source 1.
The charging unit 3 is controlled so that the current value flowing from 0 is maintained at a predetermined constant current value. Next, the state of taper charging region B will be explained. Next, as charging of the battery 4 progresses and the terminal voltage of the battery 4 rises and reaches a predetermined voltage, the voltage sensor 1 detecting the terminal voltage of the battery 4 outputs a taper charging signal 6. , is applied to the charging unit 3, and controls the charging unit 3 so that the terminal voltage of the battery 4 is below a predetermined constant voltage. In the tapered charging region described above, the charging current of the battery 4 is reduced over time. Note that in the charge amount control method, it is necessary to actually measure the discharge amount and the charge amount using a counter, which increases the scale of the circuit and poses a practical problem.

[0005]

[Problems to be Solved by the Invention] The battery charging control device applying the conventional battery constant current constant voltage charging control method described above is an effective charging method from the viewpoint of being able to perform control approximating an appropriate recharging rate. However, this cannot be said to be sufficient from the viewpoint of extending the life of the cells of the battery 4. That is, when charging progresses in the taper charging region B, the battery 4 reaches an overcharged state. When the battery 4 becomes overcharged, the balance between generation and absorption of oxygen gas within the battery 4 is disrupted, and the internal pressure of the cells of the battery 4 monotonically increases as shown in FIG. 4(c). Such an increase in the internal pressure of the cell causes deterioration of the cell performance, resulting in the disadvantage that the battery cannot be used for a long period of time.

On the other hand, a battery charging control device that operates based on the charge amount control method has a disadvantage in that the configuration is more complicated than the above-mentioned constant current constant voltage control method. Furthermore, the charge amount control method also has the drawback that deterioration progresses due to an increase in the internal pressure of the cells of the battery 4 in the latter half of the charging period.

The purpose of the present invention is to detect and control internal pressure using an internal pressure sensor to prevent overcharging in the taper charging region;
An object of the present invention is to provide a battery charging control device that can extend the life of a battery.

[0008]

[Means for Solving the Problems] The battery charging control device of the present invention charges a battery with a constant current when the terminal voltage of the battery is lower than a predetermined value, and when the terminal voltage exceeds the predetermined value, the battery is charged with a constant current. In a battery charging control device having a voltage charging unit and a voltage sensor for the terminal voltage, a reference voltage applied from the outside is inputted as the terminal voltage, and a control signal is generated when the terminal voltage is larger than the reference voltage. A voltage sensor with a built-in comparator that sends the voltage to the charging section and causes the transition to a taper charging region; and a voltage sensor that detects the internal pressure of the battery and sends a charging flow control signal to the charging section when the internal pressure is larger than a preset value. It is equipped with an internal pressure sensor for sending out the air pressure.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIGS. 2(a), (b), and (c) are characteristic diagrams of this embodiment. In the embodiment of FIG. 1, the same reference numerals as in the embodiment of FIG. 3 have the same structure. That is, this embodiment includes an internal pressure sensor 2 that detects the internal pressure of the battery cell. The voltage sensor 1 also includes a comparator 12 that compares the terminal voltage of the battery 4 with a reference voltage 13 from the outside and outputs a taper charging signal when the terminal voltage of the battery 4 exceeds the reference voltage 13.

Next, the operation of this embodiment will be explained. The internal pressure sensor 2 detects the internal pressure of the cells of the battery 4, and when the internal pressure reaches a preset value, outputs a charging current control signal to control the charging unit 3. In FIG. 1, when the battery 4 is discharged and the terminal voltage of the battery 4 is lower than the external reference voltage 13, the voltage sensor 1 does not operate. Since the internal pressure of the cells of the battery 4 is also low, the internal pressure sensor 2 does not operate. In this state, the charging section 3 is controlled by the control output of the current sensor 7 to perform constant current charging, as shown in the conventional example (FIG. 3). This state is shown in Figures 2(a), (b), and (c).
This corresponds to the full charging area A. As charging progresses and the terminal voltage of the battery becomes equal to or higher than the external reference voltage 13, the comparator 12 operates and the voltage sensor 11 outputs a taper charging signal 6A, which is applied to the charging section 3 as a control signal. Through this control, a current of charging to the battery 4 is supplied to the charging section 3 so that the terminal voltage of the battery 4 becomes equal to or lower than the reference voltage 13.
controlled by This state is shown in Figures 2(a), (b), and (c).
This corresponds to the taper charging area B. Under such a tapered charging region, as time passes, the internal pressure of the cells of the battery 4 decreases once as shown in FIG. 2(c), but then increases again. When the internal pressure of this cell increases and exceeds a preset value, the internal pressure sensor 2 that monitors the internal pressure of the cell of the battery 4 operates and outputs a charging flow control signal. Charging part 3
While this internal pressure taper charging signal is applied, the charging current is reduced to keep the internal pressure of the cells of the battery 4 below a certain value. Such a state corresponds to the tapered charging region c shown in FIG. 2(c).

0012

Effects of the Invention As explained above, the present invention provides a battery internal pressure sensor and a comparator with a reference voltage in the voltage sensor, so that the charging current can be maintained in order to maintain the internal pressure below a predetermined level. is continuously reduced, which has the effect of making it possible to charge the battery without applying charging stress to the battery. Therefore, it is possible to provide a battery charging control device that can extend battery life more than before without significantly reducing charging control performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a battery charging control device according to an embodiment of the present invention.

FIG. 2 is a characteristic explanatory diagram showing charging characteristics of this embodiment.

FIG. 3 is a block diagram of a conventional battery charging control device.

FIG. 4 is a characteristic explanatory diagram of a conventional battery charging control device.

[Explanation of symbols]

1,11 Voltage sensor 2 Internal pressure sensor 3　　　　Charging part 4 Battery 6 Taper charging signal 7 Current sensor 8 Discharge diode 9 Load 10 Power supply 12 Comparator 13 Reference voltage

Claims (2)

[Claims] 1. A charging unit that charges a battery with a constant current when the terminal voltage of the battery is lower than a predetermined value and with a constant voltage when the terminal voltage exceeds the predetermined value, and a voltage sensor for the terminal voltage. In the battery charging control device, a reference voltage applied from the outside is inputted to the terminal voltage, and when the terminal voltage is larger than the reference voltage, a control signal is sent to the charging unit, and the transition to a taper charging region is performed. and an internal pressure sensor that detects the internal pressure of the battery and sends a charging current control signal to the charging section when the internal pressure is greater than a preset value. battery charging control device. 2. While the charging unit is inputting the internal pressure taper charging signal from the internal pressure sensor, the charging current is reduced to keep the internal pressure of the battery cell below a certain value. The battery charging control device described.