JPH0449819A - Battery charging controller - Google Patents

Abstract

PURPOSE:To lengthen the lifetime of a battery by continuously reducing charging currents for holding internal pressure at a determined level or less. CONSTITUTION:When charging progresses and battery terminal voltage reaches reference voltage of 102V or more, a comparator 101 is operated, a tapered charging signal 6 is applied to a charging section 3 from a voltage sensor 100, and charging currents are controlled so that battery terminal voltage reaches reference voltage or less. When the internal pressure of the cell of a battery 4 rises with the lapse of time and reaches a preset value or more, an internal pressure sensor 2 is operated, and the contact S2 of a switch 103 is closed. When battery inter-terminal voltage is higher than the inter-terminal voltage of a resistor R2, the comparator 101 applies the tapered charging signal 6 to the charging section 3, charging currents are lowered so that battery voltage reaches voltage or less between both ends of the resistor R2, and the internal voltage of the cell of the battery 4 is reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a battery charging control device, and particularly to a battery charging control device that repeatedly charges a battery used in an artificial satellite, etc. from a solar cell and discharges the battery from the battery to a load. In particular, the present invention relates to a battery charging control device for ensuring proper charging.

[Conventional technology]

In general, battery charge control methods include a charge amount control method, that is, a method that controls the charge amount so that the charge amount/discharge amount is a constant ratio (approximately 1.05 to 1.2), or an approximate charge amount control method. As a control method, there is a constant current constant voltage control method (for example, Taber charging method) using charging voltage detection.

Conventionally, as a battery charging control device realizing a constant current constant voltage control method, for example, as shown in the block diagram of FIG. Power source consisting of a pond etc. 10. A charging unit 3 that controls charging current, a battery 4 to be charged. A load 9 represented by a voltage sensor 12 for detecting battery charging voltage and a communication device. It is composed of a discharging diode 8 that forms a discharging 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. A conventional example will now be described with reference to the characteristics of a general battery charging current shown in the explanatory diagram of FIG. 4(a).

The output from the power source 10 is supplied to the battery 4 with the charging current controlled by the charging section 3 . A current sensor 7 is inserted in series between the battery 4 and the power source 10. 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 When the current exceeds a predetermined current value, this current sensor 7 outputs a control signal to the charging unit 3, and the current value flowing into the battery 4 from the power source 10 is adjusted to a predetermined constant current value. The charging unit 3 is controlled so as to maintain the voltage. This state corresponds to the full charging region A in FIG. Subsequently, charging of the battery 4 progresses, and the voltage between the terminals of the battery 4 increases, and when it reaches a predetermined voltage, the voltage between the terminals of the battery 4 is detected from the voltage sensor 1. The Taber charging signal 6 is outputted and applied to the charging section 3, and the charging section 3 is controlled so that the terminal voltage of the battery 4 is below a predetermined constant voltage.

This state corresponds to Taber charging region B in FIG.

In the above-mentioned taper charging region, the charging current of the battery 4 decreases over time.6 Note that in the charge amount control method, it is necessary to actually measure the discharge amount and charge amount using a counter, and the charge amount and discharge amount are It is not often used because it is difficult to measure.

[Problem to be solved by the invention]

The conventional battery constant current voltage charging control method described above is an effective charging method from the perspective of being able to perform control approximating an appropriate recharging rate, but it is not sufficient from the perspective of extending the life of the cells of the battery 4. In other words, if charging progresses in the taper charging region B, the battery 4 reaches an overcharged state.

When the battery 4 enters an overcurrent state, the electrolyte in the battery 4 is decomposed and gas is generated. As the composition of the electrolyte changes due to the generation of this gas, the internal pressure of the cell of the battery 4 monotonically increases as shown in FIG. This has the disadvantage that the cell performance deteriorates further. Therefore, it has been difficult to use the battery for a long period of time.

In addition, battery charging control devices that operate based on the charge amount control method have the disadvantage that the configuration is more complex than the constant current voltage control method described above, and the battery charging control device that operates based on the charge amount control method has the disadvantage that This had the disadvantage that deterioration progressed due to an increase in the internal pressure of the cells of the battery 4 in the latter half of the period and an accompanying change in the composition of the electrolytic solution.

It is an object of the present invention to provide a battery charging control device that can extend the life of a battery without making the conventional battery charging control device of this type so complicated.

[Means to solve the problem]

In a battery charging control device having a charging circuit 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, the terminal voltage means having a reference voltage as a first input and a reference voltage as a second input, outputting a control signal and applying it as a control signal to the charging circuit when the first input voltage is larger than the voltage of the second input; means for generating a first voltage lower than the reference voltage and a second voltage lower than the first voltage;
an internal pressure sensor that generates a switch control signal when its own internal pressure is greater than a preset value; and an internal pressure sensor that selects and outputs the second voltage as the reference voltage when the switch control signal is applied, and the switch control signal means for selectively outputting the first voltage as the reference voltage when the voltage is not available.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing one embodiment of the present invention. In this embodiment, an internal pressure sensor 2 detects the internal pressure of a battery cell.
have. The voltage sensor 100 also includes a comparator 101 that compares the terminal voltage of the battery 4 with a reference voltage from the outside and outputs a Taber charging signal when the terminal voltage of the battery 4 exceeds the reference voltage. Furthermore, resistors R1 and R2 for dividing a reference voltage from the outside are connected in series within this voltage sensor, and a reference voltage 102 is applied to one end of the resistor R1. A connection point between resistors R1 and R2 is connected to contact S2 of switch 103 in voltage sensor 100, and the other end of R2 is grounded. A reference voltage 102 from the outside is supplied to the contact S1 of the switch 103 described above. The switch 103 has a contact S1 that connects the reference voltage input side of the comparator 101 to the external reference voltage 102, and a contact S2 that connects the reference voltage input side of the comparator 101 to the connection point of resistors R1 and R2 that divides the reference voltage 102 and supplies a voltage lower than the reference voltage. There is.

The switch 103 is a switch whose contact S2 closes only when a switch control signal is applied from the internal pressure sensor 2, and whose contact S1 closes otherwise. 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 switch control signal and applies it to the switch 103.

When the battery 4 in FIG. 1 is discharged and the terminal voltage of this battery 4 is lower than the external reference voltage, the voltage sensor 1
00 does not operate. Since the internal pressure of the cell of battery 4 is also low, the internal pressure sensor 2 does not operate. In such a state, the current is indicated as in the conventional constant current constant voltage battery charging control device shown in Fig. 3. This corresponds to full charge area A.

As charging progresses and the terminal voltage of the battery becomes equal to or higher than the external reference voltage 102, the comparator 1/-taper 101 operates and the voltage sensor 100 outputs the Taber charging signal 6, which is applied to the charging section 3 as a control signal and is applied to the battery. The charging current to the battery 4 is controlled by the charging unit 3 so that the terminal voltage of the battery 4 becomes equal to or lower than the reference voltage 102. This state corresponds to B of the Taber charging region in FIG. Under such a Taber charging region, as time passes, the internal pressure of the cells of the battery 4 reaches the second level.
As shown in the figure, it drops once, but then rises 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 switch control signal.

This switch control signal is applied to switch 103, closing contact S2 within switch 103. Therefore, the reference voltage input to the comparator]01 is the reference voltage 1 from the outside.
02 divided by resistors R1 and R2, that is, a voltage lower than the external reference voltage 102. Therefore, when the voltage across the terminals of the battery 4 is higher than the voltage connected through the contact S2 of the switch 1.03, that is, the voltage across the terminals of the resistor R2, the comparator 101 outputs the Taber charging signal 6 to control the charging section 3. . The charging section 3 reduces the charging current while the Taber charging signal 6 is applied, so that the voltage across the terminals of the battery 4 is lower than the voltage occurring across the resistor R2. If the charging current flowing through the battery 4 is reduced in this way, the internal pressure of the cells of the battery 4 is also reduced. Such a state corresponds to the Taber charging region C shown in FIG.

By appropriately setting the values of the resistors R1 and R2 in advance, the internal pressure of the cells of the battery 4 can be lowered to a desired value or less.

〔Effect of the invention〕

As explained above, the present invention continuously reduces the charging current in order to maintain the internal pressure below a predetermined level, so it is possible to charge the battery without applying charging stress to the battery. It becomes possible. That is, it is possible to provide a battery charging control device that can extend the battery life compared to conventional devices of this type without significantly reducing charging control performance. Further, it is sufficient to simply add an internal pressure sensor, a switch, and a resistor to a conventional constant current/constant voltage battery charging control device, and the device of the present invention can be obtained without making the device configuration too complicated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing charging characteristics of the battery of the present invention, FIG. 3 is a block diagram showing an example of a conventional battery charging control device, and FIG. The figure is an explanatory diagram showing the charging characteristics of a conventional device of this type. DESCRIPTION OF SYMBOLS 1... Voltage sensor, 2... Internal pressure sensor, 3... Charging part, 4... Battery, 6... Taber charging signal, 7
...Current sensor, 8...Discharge diode, 9...
・Load, 10...Power supply, 100...Voltage sensor.

Claims (1)

[Claims] In a battery charging control device having a charging circuit 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, the terminal voltage means having a reference voltage as a first input and a reference voltage as a second input, outputting a control signal and applying it as a control signal to the charging circuit when the first input voltage is larger than the voltage of the second input; means for generating a first voltage and a second voltage lower than the first voltage; detecting the internal pressure of the battery cell and generating a switch control signal when the internal pressure is greater than a preset value; and means for selectively outputting the second voltage as the reference voltage when the switch control signal is applied, and selectively outputting the first voltage as the reference voltage when the switch control signal is not applied. A battery charging control device comprising: