JP2627328B2 - Battery charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention relates to a charging device capable of charging a storage battery and discharging from the storage battery.

(B) Conventional technology In the case of a battery pack of Ni-Cd battery used as a power source of an electric device, for example, a camera-integrated video, the battery is discharged when its output voltage falls below a load driving threshold voltage of a motor or the like. The battery becomes exhausted, and the battery needs to be charged. By the way, the threshold voltage for driving the load is usually set to be higher than the discharge end voltage of the battery, and a small amount of remaining capacity is constantly left when the battery is charged.

As shown in FIG. 6, when the battery (B ₁ ) discharged to the discharge end voltage is once charged to a full charge and then discharged again,
Even if this operation is repeated several times, no significant change is observed in the discharge characteristics. On the other hand, as described above, when the charge / discharge cycle of charging the battery (B ₂ ) having the remaining capacity to full charge and discharging again to the extent that the remaining capacity was present was repeated, the battery was discharged to the discharge end voltage in its discharge characteristics. A phenomenon occurs in which the level of the terminal voltage is lower than that of the battery (B ₁ ). This phenomenon is called the memory effect of the battery, and when detecting the full charge of the battery by the change in the terminal voltage, it becomes difficult to reach the preset full charge voltage in the case of the battery having the remaining capacity, and the battery becomes full. There has been a problem that charging continues even after the battery has been charged.

It is well known from experience that the memory effect of such a battery is removed by forcibly discharging a battery having a remaining capacity once to a discharge end voltage, charging the battery to a full charge and repeating the same operation once more. ing.

Before starting the charging of the storage battery, the storage battery is once discharged to equalize the initial capacity of all the storage batteries and to perform uniform charging (see Japanese Patent Publication No. 60-31175). Since the memory effect is not eliminated, there is a problem that a full charge detection cannot be accurately performed by a charge control method of a battery terminal voltage detection type.

(C) Problems to be solved by the invention A problem to be solved by the present invention is to develop a storage battery charging device having a function of improving a storage battery that has become defective due to a memory effect of the battery by discharging.

(D) Means for Solving the Problems A charging power supply for supplying a charging current to a storage battery connected to a charging circuit, and a terminal when the terminal voltage of the storage battery being charged is detected and the detected terminal voltage is fully charged. A discharge circuit for discharging the storage battery which is connected to the charging means and is in a fully charged state to a discharge termination state, comprising a charging means comprising an arithmetic circuit for interrupting the charging circuit and terminating the charging by matching the voltage; And a display circuit for integrating a discharge current amount at the time of discharge by the arithmetic circuit and displaying the integrated discharge current amount as a discharge capacity, wherein when the discharge capacity does not reach a predetermined capacity, the charging is performed. The full charging operation by the means and the discharging operation by the discharging means are repeated again.

(E) Function In normal charging, a charging current is supplied from a charging power supply to a storage battery, a full charge is determined by an arithmetic circuit, and the charging circuit is cut off to terminate charging. When a rechargeable battery having a memory effect is regenerated and charged, the storage battery is once reached a fully charged state, the storage battery is discharged from this state, and its discharge capacity is displayed, thereby judging whether the storage battery is good or defective. Then, the charge and discharge are repeated to remove the memory effect.

(F) Embodiment Hereinafter, a charging device for a storage battery of the present invention will be described in detail with reference to an embodiment of the drawings.

FIG. 1 shows a basic block circuit diagram. In the figure,
(1) is a commercial AC power supply, (2) is the commercial AC power supply (1)
A charging power supply for rectifying and smoothing the AC output from the DC power supply to generate a DC charging current and outputting the charging current; (B) charging in which charging control switch means (3) is arranged in the charging power supply (2); A battery pack connected in series with five unit cells connected via a path (4) and supplied with the charging current, (5)
Is a discharge circuit connected to the storage battery (B) via the discharging switch means (6) to discharge the remaining capacity of the storage battery (B). (7) detects a terminal voltage of the storage battery (B) during charging. When the terminal voltage reaches a predetermined end-of-charge voltage, the charge control switch means (3) is opened to interrupt supply of charging current to the storage battery (B), and the discharge switch means (6) is closed. An arithmetic circuit that integrates the discharge current during discharge and inputs the integrated value as a discharge capacity to the display circuit (8).

FIG. 2 is a circuit diagram showing one embodiment in which the above basic block circuit is applied to an actual charger. In the figure, a transistor (Q1) has its emitter-collector circuit connected to a storage battery (B).
The resistor (R) is a discharging resistor, which is inserted in the charging circuit of FIG.
The transistor (Q2), which functions as a discharge circuit (5) in FIG. 1, is connected between the resistor (R) and the storage battery (B), and functions as a discharge switch means in FIG. In FIG. 2, the arithmetic circuit (7) in FIG. 1 is a 4-bit microcomputer (manufactured by Sanyo Electric).
LC6520H) (9) and A / D conversion circuit (ladder resistance circuit, etc.)
(10) and a multiplexer (NEC μPD4051 (11). The microcomputer (9) supplies + V power from a [power supply for charging (2)] through a resistor (R6) and a light emitting diode (LED6). Connect to the output terminal (P11) .Light emitting diodes (LED1) to (LED5) are resistors (R1) to
Together with (R5), they are connected to the power supply (+ V) and the output terminals (P1) to (P5) of the microcomputer (9), respectively, and function as the display circuit (8) in FIG. The multiplexer (11) selectively receives either the terminal voltage of the storage battery (B) during charging or the voltage across the discharge resistor (R), and converts the received data into an A / D conversion circuit (10). Is input to the output terminal (P6) of the microcomputer (9) as an 8-bit signal via the. The microcomputer (9) receiving this input outputs an operation signal to the base resistance (R7) of the transistor (Q1), the base resistance (R8) of the transistor (Q2), or the light emitting diodes (LED1) to (LED5). .

In the above circuit diagram, when the charging power supply (2) is turned on, the microcomputer (9) stores the reference values of the charge end voltage and the discharge end voltage. When the storage battery (B) is set in the circuit, first, the transistor (Q1) ) Is turned on, the transistor (Q2) is turned off, and a charging current is supplied from the charging power source (2) to the storage battery (B). During this time, the multiplexer (11) successively detects the terminal voltage of the storage battery (B) and continues charging until reaching the voltage at the time of full charge. Then, during charging, the output terminal (P11) of the microcomputer (9) is at the "L" level, and the light emitting diode (LED6) is lit to indicate that charging is in progress.

In normal charging, when the terminal voltage of the storage battery (B) reaches the voltage at the time of full charge, the voltage is supplied from the multiplexer (11) via the A / D conversion circuit (10) to the microcomputer (9).
The microcomputer (9) inverts the output of its output terminal (P10), turns off the transistor (Q1), terminates charging, and turns off the light emitting diode (LED6).

When it is suspected that the storage battery (B) has a memory effect, the program of the microcomputer (9) is manually changed. For example, in the case of a charger having a plurality of battery storage sections, a method of changing the program of the microcomputer (9) by providing a battery storage section dedicated to removing the memory effect and storing the target storage battery (B) therein. Is an example. In the case of charging the storage battery (B), when the terminal voltage of the storage battery (B) reaches the voltage at the time of full charge, the A / D conversion circuit (1) is output from the multiplexer (11).
0) is input to the microcomputer (9), which inverts the output of the output terminal (P10), the transistor (Q1) becomes non-conductive, and the light emitting diode (LED6) Goes off, the output of the output terminal (P9) is inverted, and the transistor (Q
2) becomes conductive. Therefore, the storage battery (B) discharges through the discharge resistor (R). The current resulting from the discharge is supplied to the microcomputer (9) in the form of a terminal voltage via an A / D conversion circuit (10) by taking in the terminal voltage of the resistor (R) by the multiplexer (11). The microcomputer (9) sends a start signal to each of the light emitting diodes (LED1) to (LED5) based on the input data, and turns on the light emitting diodes (LED1) to (LED5) as shown in the following table.

Next, a method of calculating the discharge capacity will be described with reference to FIG. In the figure, the vertical axes Vo to Vn indicate the terminal voltage of the discharge resistor (R) taken into the multiplexer (11) by the A / D converter (10) by the A / D converter (10) at the sampling intervals o to n every minute. Indicates the D-converted voltage value. Vs indicates the discharge end voltage, which is set to 1 [V] per unit cell in advance in the microcomputer (9). That is, when the storage battery (B) is discharged to the voltage Vs, the microcomputer (9) detecting this discharge turns off the transistor (Q2) and stops discharging the storage battery (B), thereby preventing overdischarge.

The discharge capacity is obtained by the following equation by trapezoidal approximation of the discharge curve (12) with the voltage every minute.

Therefore, assuming that the nominal capacity of the storage battery (B) is Y, the discharge capacity can be calculated as Y ₁ / Y × 100 [%].
The result is obtained within the light emitting diode (LED1)-(LE
D5).

FIG. 4 shows a flowchart of the above-described discharge program, and FIG. 5 shows a flowchart of the discharge routine program in FIG. In this case, the discharge capacity [%] in the first discharge
If it exceeds 60, it is recharged and the charging is terminated in the same manner as a normal storage battery (B). On the other hand, when it is less than 60, it is discharged again and then discharged again. End charging. This is to take advantage of the fact that the discharge capacity [%] does not exceed 60 when the defective battery having the memory effect of the battery is discharged, and to regenerate the defective battery in the next charge and discharge.

 In FIG. 5, the reference numerals are as follows.

V _n : Terminal voltage of discharge resistor (R) detected at that time V _n-1 : Terminal voltage of discharge resistor (R) detected last time (one minute before) Y _n : Discharge capacity up to this time [%] Y _n-1 : Discharge capacity up to the previous time [%] (g) Effect of the Invention As described above, the present invention provides a charging power supply for supplying a charging current to a storage battery connected to a charging circuit, and the storage battery being charged And an arithmetic circuit for terminating the charging by interrupting the charging circuit when the terminal voltage of the storage battery is equal to the terminal voltage of the battery, and discharging the storage battery that is connected to the charging means and is in a fully charged state to a discharge termination state. Circuit, and a discharge circuit comprising a display circuit for integrating the discharge current amount at the time of discharge by the arithmetic circuit and displaying the integrated discharge current amount as a discharge capacity, and when the discharge capacity does not reach a predetermined capacity, Full charge operation by the charging means and before Since those repeating the discharge operation by the discharge means again, the charging device and the discharging device can structurally integrated, there is no need to prepare separately.

By discharging the storage battery to the discharge end state,
The memory effect can be eliminated.

Since the discharge capacity from the fully charged state of the storage battery to the end of discharge is displayed, the current state of performance deterioration of the storage battery can be determined at a glance.

And other effects can be expected.

[Brief description of the drawings]

FIG. 1 is a basic block circuit diagram showing a battery charging device of the present invention, FIG. 2 is a block circuit diagram showing one embodiment of a circuit based on the block circuit diagram of FIG. 1, and FIG. 3 is a discharge characteristic of the battery. FIG. 4 is a flowchart showing a discharge program, and FIG.
FIG. 4 is a flowchart showing the discharge routine of FIG. 4, and FIG. 6 is a discharge characteristic diagram showing the memory effect of the battery. (B) ... storage battery, (2) ... power supply for charging, (5) ...
Discharge circuit, (7) arithmetic circuit, (8) display circuit.

Claims (1)

(57) [Claims] 1. A charging power supply for supplying a charging current to a storage battery connected to a charging circuit, and a terminal voltage of the storage battery being charged is detected, and the detected terminal voltage matches the terminal voltage when fully charged. A discharging circuit connected to the charging means for discharging the storage battery in a fully charged state to a discharging end state, and a discharging circuit for discharging at the time of discharging. A discharge circuit comprising a display circuit for integrating the amount of current by the arithmetic circuit and displaying the integrated discharge current amount as a discharge capacity, and when the discharge capacity does not reach a predetermined capacity, a full charge operation by the charging means. And a discharging operation by the discharging means is repeated again.