JP2000324709A - Charging device - Google Patents

Abstract

(57) [Summary] In a conventional battery charger for a plurality of batteries, the battery is charged in order, so that the user can use, for example, four batteries.
Even if the user wants to move the device driven by the battery in a short time, he or she has to wait until the fourth battery is charged for a certain time. SOLUTION: A power supply unit 1 for supplying a charging current, a charging control circuit unit 2 for performing a charging control, and switch elements SW1 to SW4 for performing a charging current control are provided to supply a charging current to a battery B1 for a predetermined time. After that, the charging current is supplied to the battery B2 at the same time, and the charging current is supplied to all the connected batteries as one charging cycle T, and the charging cycle T is repeated until the completion of the charging is detected. In addition, it is possible to provide a charging device that can charge a plurality of connected batteries at the same capacity with an inexpensive configuration, and has an excellent effect that the capacity variation between the batteries does not easily occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for charging a rechargeable battery such as a nickel cadmium storage battery or a nickel hydride storage battery.

[0002]

2. Description of the Related Art Conventionally, as a charging method for charging a rechargeable battery such as a nickel cadmium storage battery or a nickel hydride storage battery, a charging current controlled at a constant current is continuously supplied to a battery to be charged, and the battery voltage peaks. A charge control method for detecting completion of charging and detecting completion of charging after that, that is, a so-called -ΔV control method, has been widely used. FIG. 3 shows a circuit block diagram, and FIG. 4 shows a charging current and a battery voltage according to the conventional method.

In FIG. 3, reference numeral 11 denotes a charging device, in which a DC power supply 12, a switch element 13, and a charging control unit 1 are provided.
4. A constant current control unit 15 is provided. Reference numeral 17 denotes a secondary battery to be charged. The DC power supply 12 is connected to an external AC power supply, supplies a charging current, and outputs a constant current in a constant current control unit. Then, the charging current is turned on and off by the switch element 13, and the charging current is supplied for a predetermined time or stopped. The charge control unit 14 detects the battery voltage and detects the completion of charging.

[0006] The charging operation in this configuration is performed by using the voltage
This will be described with reference to a current correlation diagram. In FIG. 4, I is a charging current controlled by a constant current, and flows to the battery continuously from the start of charging to the completion of charging. Vb is the battery voltage,
The voltage rises as the charging progresses due to the charging current I, and when the charging is completed, the battery voltage Vb reaches a peak due to self-heating inside the battery, and then starts decreasing. The battery voltage drop after this voltage peak is detected to detect the completion of charging of the battery.

In this conventional configuration, when a plurality of batteries (for example, four batteries) are charged at the same time, a battery shown in FIG.
As shown in the voltage-current correlation diagram, it was necessary to first complete the charging of the battery B1 to a fully charged state, and then proceed to charging the battery B2. After the charging of the battery B2 was completed, the batteries B3 and B4 had to be similarly charged in order.

When four batteries are simultaneously charged, four constant current circuits and four charge control circuits are provided, or at least four constant current circuits and one charge control circuit as shown in FIG. Was needed.

In the conventional device shown in FIG. 3, since the battery voltage is always detected while the charging current is flowing, the voltage drop due to the charging current occurs in the contact resistance between the output terminal of the charging device and the battery terminal. Occurs, and the charging control unit 14 of the charging device detects the voltage obtained by adding the voltage drop in the contact resistance of the terminal to the actual battery voltage as the battery voltage. Therefore, the contact resistance between the charging device output terminal and the battery is detected. Changes, the voltage drop at this contact resistance also changes,
The charge control unit considers that the battery voltage has changed. In the charging control method that detects that the battery voltage has peaked and dropped, if the voltage drop in the contact resistance increases, it is determined that the battery voltage has risen and there is no problem, but if the voltage drop in the contact resistance decreases. Is detected as a drop in battery voltage, it is determined that charging is completed, and charging ends. Specifically, when the user touches the battery during charging, or when the charging device is being charged by placing the charging device in a constantly vibrating place, there is a possibility that the charging may be terminated halfway due to the above operation. Was. In addition, it is necessary to provide a constant current control unit for the charging current so that the charging current decreases when the input voltage decreases and the battery voltage does not drop due to the reduction in the charging current, and the cost is reduced. There was also a problem that this was the case. The present inventors have solved this problem in Japanese Patent Application No. 10-171027, and the charging does not end prematurely even if the contact resistance between the battery charger output terminal and the battery changes. A charging device that does not require a constant current control unit has already been proposed.

[0008]

However, in the charging device described in Japanese Patent Application No. 10-171027, charging of a plurality of batteries is not taken into account. Charge the batteries in order as shown, or
It was necessary to configure an expensive device as shown in FIG.
In the case of a configuration in which batteries are sequentially charged, even if a user wants to move a device driven by four batteries in a short time, it is necessary to wait until the fourth battery is charged for a certain time. There was an inconvenience. Also, if the user wants to use only two of the four charged batteries early,
It is conceivable to notify the user of the charged battery by display or the like so that the battery can be used. However, adding a display device or the like makes the entire device expensive, and also causes a difference in the use time of each storage battery. For this reason, there is a possibility that the degree of deterioration is varied, and when all four batteries are used, there is a possibility that only a considerably shorter time than the scheduled time can be used.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a charging apparatus which can charge a plurality of batteries simultaneously, in other words, with the same capacity, with an inexpensive configuration.

[0010]

In order to achieve the above object, a charging apparatus according to the present invention comprises a power supply unit for converting a commercial power supply into a direct current and supplying a charging current, and a charging control for detecting a battery voltage and performing a charging control. A battery unit, and a plurality of switch elements that receive a signal from the charge control circuit unit and perform ON-OFF control of a charging current. Supply charging current to B2,
Performing this for all the connected batteries is referred to as one charging cycle T, and the charging cycle T is repeated until the completion of charging is detected. This makes it possible to provide a charging device that can charge a plurality of connected batteries for the same capacity with an inexpensive configuration, and has an excellent effect of preventing variations in capacity between batteries.

Further, by detecting the voltage of each battery during the charging current suspension time, it is possible to perform error-free detection, and since a plurality of batteries are charged, the voltage of the other battery B1 is detected when the battery B2 is charged. To be able to do
There is also an excellent effect that no loss of charging time occurs.

Further, by setting the charging current supply time to one battery per cycle to a constant value of 0.1 second or more and 0.8 second or less, accurate battery voltage detection can be performed without deterioration of the battery. Can be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to a circuit block diagram shown in FIG. 1 and a charging current time chart shown in FIG.

In FIG. 1, reference numeral 1 denotes a DC power supply for converting AC current to DC and supplying a charging current to the entire apparatus.
Is a charge control circuit that detects at least the voltage of each battery and detects the completion of charging. In the present embodiment, a case where four batteries (B1 to B4) are charged is shown.
The effect of the present invention is not limited to this case, and it goes without saying that the present invention is always effective when charging two or more batteries.

SW1 to SW4 are switch elements for receiving an output from the charge control circuit, turning on / off the charge current to the corresponding batteries B1 to B4, and supplying or stopping the charge current for a predetermined time. .

The operation of the charging device configured as described above will be described below. First, the charging control circuit unit 2 detects that the battery is mounted at a predetermined position, outputs a charging start signal, turns on the switch element SW1, and switches the DC power supply 1 to the battery B1 via the switch element SW1. A charging current flows, and charging is started. After a lapse of time T1 from the start of charging, the charging control circuit unit 2 issues a charging current OFF signal for the time T0, and the supply of the charging current to the battery B1 is stopped.

During the charging current suspension time T0, the charging control circuit 2 reads the voltage of the battery B1, and the detected voltage is changed to the actual battery voltage VB1 by the charging device output +
Between terminal and battery + terminal, and charger output-terminal and battery-
A voltage VB1 'is obtained by adding a voltage drop generated by the flow of the charging current to the contact resistance between the terminals.

However, the above-mentioned Japanese Patent Application No. Hei.
By performing the battery voltage detection during the charging current stop time as shown in No. 27, the voltage VB1 ′ becomes the actual battery voltage VB.
The value can be substantially equal to 1. In addition, when charging a plurality of batteries at the same time as in the present application, any one of the batteries is charged during the charging current stop time T0 for the battery B1, and therefore, T0 = T1 = T3 (battery). 4), T0 = T1 (2 batteries), etc., and it is not necessary to consider the value of the charging pause time. This is advantageous.

After a lapse of time T1 from the start of charging,
As described above, the supply of the charging current to the battery B1 is stopped. At the same time, the signal output from the charging control circuit unit 2 turns on the switch SW2 to start supplying the charging current to the battery B2. As in the case of the battery B1, the charging of the battery B2 is stopped by issuing a charge current OFF signal for the time T0 from the charge control circuit unit 2 after a lapse of time T2 (T2 = T1).

Similarly, at the same time as the supply of the charging current to the battery B2 is stopped, SW3 is turned on by the signal output from the charging control circuit 2, and the supply of the charging current to the battery B3 is started. As in the case of the battery B1, the charging of the battery B3 is stopped by issuing a charge current OFF signal for a time T0 from the charge control circuit unit 2 after a lapse of time T3 (T3 = T1).

Similarly, at the same time as the supply of the charging current to the battery B3 is stopped, SW4 is turned on by the signal output from the charging control circuit unit 2, and the supply of the charging current to the battery B4 is started. As in the case of the battery B1, the charging of the battery B4 is stopped by issuing a charge current OFF signal for the time T0 from the charge control circuit unit 2 after a lapse of time T4 (T4 = T1).

The time (T1 + T2 + T3 + T3) for completing the supply of the charging current to the batteries B1 to B4 once at a time.
4) is defined as one charging cycle T, and charging is continuously performed in this charging cycle T until the battery is fully charged. In the above description, charging is always performed in the order of the batteries B1, B2, B3, and B4. However, in the next cycle, charging may be performed in the reverse order, or charging may be performed in a random order. .

The voltage of the battery whose charging current has been stopped starts to drop, but considering that the gradient of the battery voltage drop immediately after stopping the charging current is steep, the voltage reading of the battery B1 is started in the latter half of the period T2. It is desirable to perform it during the T3 period or the T4 period. After the start of the reading, the battery voltage is read at points at regular time intervals, the average value of all the read values is calculated, and this average value is stored as the detected voltage VB1 'of the battery B1 at the time of this detection. Similarly, the reading of the voltage of the battery B2 starts in the T4 period or the T1 period, and the reading of the voltage of the battery B3 starts in the T1 period or the T1 period.
It is desirable that the voltage reading of the battery B4 be started in the T2 period or the T3 period for two periods.

The charge control circuit 2 reads the VB1 'at the time of each detection and compares it with the VB1' at the previous detection. Update and store. If the value is lower than the previous value, the value is not updated as a peak value, and is read next time and one after another. When VB1 ′ lower than the stored peak value by a predetermined voltage or more continues for a predetermined number of times, the battery B1 Is determined to be fully charged. In addition,
The same applies to batteries B2, B3, and B4.

For the battery for which the above-described full charge determination is made, the ON operation of the corresponding switch elements SW1 to SW4 is stopped thereafter, and the charging is completed. When a charge display lamp is provided for each battery as the charge display, the corresponding charge display lamp is switched from the charge display to the completion display in accordance with the full charge determination of each battery. If only one charging indicator lamp is used for all the batteries, the charging indicator lamp is switched from the charging display to the completion display when all the batteries are determined to be fully charged, and the charging is completed. It should be noted that trickle charging may be performed thereafter for a battery that has been determined to be fully charged.

The charging current supply time is desirably set to a constant value of 0.1 seconds or more and 0.8 seconds or less. This is because, according to the experimental data, if the time is shorter than 0.1 second, the voltage at the portion where the voltage drop is steep is read, so that the voltage of the accurate value cannot be detected. (Error) and the error at each measurement time are large, so that accurate voltage detection cannot be performed. In addition, since the charging current supply time is too close, the influence of contact resistance and the like appears, accurate voltage detection cannot be performed. This is because the possibility is high. When four batteries are charged by the device of the present invention, the voltage detection of B1 is performed by T3 as described above.
However, in this case as well, it is necessary to change settings and specifications to change the charging current supply time in accordance with the number of connected batteries, which causes a cost increase. Considering that there is no merit even if it is shorter than 1 second, it is desirable to set the same charging current supply time even when charging three or more batteries as when charging two batteries.

Further, in the present invention, in order to make the time required for charging equal to that of the related art, the amount of charge for one battery in one cycle is made substantially equal to the amount of charge that is normally charged at a normal 1C. That is, when two batteries are charged, an excessive current, for example, nearly twice the standard value is supplied during the charging current supply time. For this reason, if the time is longer than 0.8 seconds, a case in which the battery deteriorates due to an excessively long period in which an excessive current flows through the battery has been accepted. Therefore, preferably, the charging current supply time is set to a constant value of 0.1 seconds or more and 0.8 seconds or less, for example, 0.2 seconds. In this case, the period during which the charging current supply is stopped is also 0.2 seconds or more (0.2 seconds for charging two batteries, 0.6 seconds for four batteries).
The detection of the battery voltage is started 0.1 seconds after the supply of the charging current is stopped, the battery voltage is detected a plurality of times, and the average value can be used as the battery voltage value.

[0028]

As described above, according to the present invention, a plurality of connected batteries can be charged at the same capacity with an inexpensive configuration.
It is possible to provide a charging device having an excellent effect in which a variation in capacity between batteries does not easily occur. In addition, by performing the voltage detection of each battery during the charging current suspension time, error-free detection can be performed, and a plurality of batteries are charged,
For example, since the voltage of the battery B1 can be detected when the battery B2 is charged, there is also an excellent effect that no loss of charging time occurs.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram according to an embodiment of the present invention.

FIG. 2 is a correlation diagram between a battery voltage and a charging current according to an embodiment of the present invention.

FIG. 3 is a conventional circuit block diagram.

FIG. 4 is a conventional correlation diagram between battery voltage and charging current.

FIG. 5 is a correlation diagram between a battery voltage and a charging current when charging a plurality of batteries according to the related art.

FIG. 6 is a circuit block diagram when a conventional battery is charged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Charge control circuit part SW1, SW2, SW3, SW4 Switch element B1, B2, B3, B4 Battery

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G003 AA01 BA04 CA02 CA16 CA17 CC02 5H030 AA03 AS18 FF42 FF43 FF44 FF52

Claims (3)

[Claims] A power supply unit for converting a commercial power supply into a direct current and supplying a charging current; a charging control circuit unit for detecting a battery voltage to perform charging control; and receiving a signal from the charging control circuit unit to turn on the charging current. -A charging device including a plurality of switch elements for performing OFF control and charging a plurality of connected batteries. After supplying a charging current to the battery B1 for a predetermined time, charging the next battery B2 for the same time A charging device characterized in that current supply is performed and the current is supplied to all of a plurality of connected batteries as one charging cycle T, and the charging cycle T is repeated until the completion of charging is detected. 2. The charging device according to claim 1, wherein voltage detection of each battery is performed during a charging current stop time. 3. The charging device according to claim 1, wherein a charging current supply time for one battery in one cycle is a constant value of 0.1 second or more and 0.8 second or less. .