JPH10322929A - Charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct quick charges at a low cost, and conduct detection of full charge accurately. SOLUTION: A commercial AC power source is connected to a constant- current power circuit 11 through a power supply plug 12. Charging output (charging current) from the constant current power circuit 11 is connected to a positive charging terminal 13a. A ground end of the constant current power circuit 11 is connected to a negative charging terminal 13b through FETs 14, 15. The charging voltage Vc of the charging terminal 13a is detected at a microcomputer 18, for controlling, a charging control signal from the microcomputer 18 is supplied to the gate of the FET 14, and the control signal of the charging current is supplied to the constant current power circuit 11. For example, the charging current matching with a battery of a large size is first supplied to the charging terminal 13a, and the charging voltage Vc of the charging terminal 13a is detected. After the voltage Vc exceeds a preset voltage Vcs, for example, the charging current matching with a battery of small size is supplied to the charging terminal 13a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging apparatus suitable for use in charging a plurality of types of batteries having different capacities, for example.

[0002]

2. Description of the Related Art For example, in a charging apparatus for charging a plurality of types of batteries having different capacities, charging with an appropriate charging current according to each capacity has conventionally been considered.
Therefore, according to such a charging device, since charging is always performed with an appropriate charging current, rapid charging can be performed safely and reliably.

However, in such a charging device, the capacity of the battery cannot be determined from, for example, the charging current. Therefore, conventionally, for example, a mechanism for determining the type is provided on the battery side, and a mechanism for detecting the type is provided on the charging device side, and the capacity of the battery is determined by these determination mechanisms to optimize the above-described charging current. And so on. However, such a method requires a determination mechanism for both the battery and the charging device, which leads to an increase in manufacturing cost and the like.

In such a charging device, the detection of the full charge (complete charge) of the battery is, for example, a phenomenon that the voltage of the charge terminal slightly drops after the battery is fully charged (−ΔV).
Can be detected and performed. However, in such a method of detecting a change in the charging voltage, for example, when the internal resistance of the battery is increased during charging at a low temperature or after long-term storage, the charging voltage rapidly increases immediately after the start of charging. , FIG.
As shown in A of FIG.
ΔV may not be detected.

Further, in charging a battery after long-term storage, for example, as shown in FIG. 7B, the charging voltage may suddenly rise immediately after the start of charging and then return to normal. In this case, as shown in the figure, when the charging voltage that has rapidly increased returns to normal, the voltage may temporarily decrease, and this decrease in voltage may be erroneously detected as -ΔV. In some cases, charging is not reliably performed, such as when charging is stopped due to such erroneous detection.

[0006] On the other hand, for example, a charging current corresponding to a battery having a minimum capacity is set, and all types of batteries are charged with the charging current. According to this, the battery can be charged most safely, and there is no need to provide a mechanism for discriminating the type of the battery, and reliable charging can be performed at low cost. However, in this method, when charging a large-capacity battery, the charging time is extremely long. For example, in a situation where frequent charging is required, operation may not be performed smoothly.

Therefore, the charging current is further set to be twice or more as described above, and all kinds of batteries are charged with the charging current. According to this, the charging time can be reduced without increasing the cost.

In this case, the detection of the full charge of the battery (completion of charging) can be performed, for example, by detecting when the voltage of the charging terminal does not increase (Vpeak). That is, in this method, when charging is performed normally, the voltage of the charging terminal increases as shown by the curve a in FIG. By detecting when this voltage stops rising (Vpeak) and stopping charging, the battery can be fully charged efficiently.

However, in this method, for example, in charging at a low temperature or charging a battery after long-term storage, the charging voltage sharply rises immediately after the start of charging because the internal resistance of the battery is high, for example. As shown by a curve b in FIG. 8, the upper limit voltage Vcmax of the circuit may be fixed and erroneously detected as Vpeak. Then, the charging is stopped due to such erroneous detection, or thereafter, the battery is shifted to supplemental charging (trickle charging) corresponding to spontaneous discharge of the battery. In any case, the battery cannot be fully charged.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and the problem to be solved is that when performing rapid charging, a conventional device uses a battery and a charging device. Requires a discriminating mechanism, which leads to an increase in manufacturing cost and the like.
In the method of detecting a voltage change such as V or Vpeak, the detection is not accurately performed in the charging of the battery at a low temperature or after long-term storage, and the battery may not be fully charged. is there.

[0011]

Therefore, according to the present invention, charging of all batteries is started with a charging current corresponding to the battery of the maximum capacity to be connected, and the charging terminal voltage of the batteries reaches a predetermined voltage. When charging is performed, charging is performed by reducing the value of the charging current. According to this, it is possible to perform rapid charging satisfactorily at low cost and to accurately detect full charging. Can be.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a charging apparatus in which a rechargeable battery is connected and supplies a controlled current to the battery to charge the battery. The charging of all the batteries is started with the current, the charging terminal voltage of the batteries is detected, and when the detected voltage reaches a predetermined voltage, the charging is performed by reducing the value of the charging current.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an example of a charging apparatus to which the present invention is applied.

In FIG. 1, a commercial AC power supply (not shown) is connected to a constant current power supply circuit 11 through a power supply plug 12. The charging output (charging current) from the constant current power supply circuit 11 is connected to the positive charging terminal 13a. The ground terminal of the constant current power supply circuit 11 is connected to the negative charging terminal 13b through the FETs 14 and 15.

Note that between these charging terminals 13a and 13b,
For example, a small-sized rechargeable battery as shown in FIG. 1B or a large-sized rechargeable battery as shown in FIG. 1C is connected. Here, the large-sized rechargeable battery is, for example, a battery in which small-sized rechargeable batteries are built in parallel, and has an increased charging capacity and a reduced internal resistance.

Further, an output terminal of a signal for judging the presence or absence of connection of the commercial AC power supply of the constant current power supply circuit 11 is connected to the base of the npn transistor 16, and the collector of the transistor 16 is connected to the charge output of the constant current power supply circuit 11 and FE
It is connected to the base of a pnp transistor 17 provided between the gate of T15. Thus, it is designed that the FET 15 is cut off when the connection of the commercial AC power supply is lost.

The power supply V _DD from the constant current power supply circuit 11
Is supplied to the microcomputer 18 for control. The microcomputer 18 includes a constant current power supply circuit 11.
Is connected to the positive charging terminal 13a, and the charging voltage Vc of the positive charging terminal 13a is A / D converted and detected. Further, a charge control signal from the microcomputer 18 is supplied to the gate of the FET 14, and
A control signal for the charging current is supplied to the constant current power supply circuit 11.

In the microcomputer 18, for example, when a commercial AC power is supplied from the power plug 12 and the battery is detected to be mounted by a signal from the battery detection switch 19, for example, the constant current power supply circuit 11 is provided. , A charging current control signal is supplied to the charging terminal 13a at first.
Supplied to

Further, in this state, the microcomputer 1
In step 8, the charging voltage Vc of the charging terminal 13a is detected, and it is determined whether or not this voltage Vc has exceeded a set voltage Vcs of, for example, about 80% of the upper limit voltage Vcmax of the circuit. When the voltage Vc> Vcs, a charging current control signal is supplied to the constant current power supply circuit 11, and thereafter, a charging current corresponding to, for example, a small-sized battery is supplied to the charging terminal 13a.

The microcomputer 18 detects a voltage change such as -ΔV or Vpeak of the charging voltage Vc at the charging terminal 13a. When the voltage change is detected, the microcomputer 18 responds to the charging control signal from the microcomputer 18 according to the charging control signal. , FET 14 is turned off. Note that this FE
After T14 is cut off, supplementary charging (trickle charging) equivalent to natural discharge is performed through the trickle resistor 20.

That is, in this device, the charging terminal 13
If, for example, a large-sized battery is connected between a and b, the charging voltage Vc is changed, for example, as shown in FIG. The connected battery can be fully charged, for example, by detecting a voltage change of -ΔV of the charging voltage Vc. As a result, a large-sized battery can be charged quickly.

On the other hand, if, for example, a small-sized battery is connected between the charging terminals 13a and 13b, the charging voltage Vc is, for example, as shown in FIG. A or B of FIG. Here, in the case of FIG. 3A, full charge can be detected, but in the case of B, for example, the internal resistance of the battery is increased by charging at a low temperature or charging after long-term storage. In case
Immediately after the start of charging, the charging voltage sharply rises, is fixed at the upper limit voltage Vcmax of the circuit, and there is a possibility that -ΔV cannot be detected.

Therefore, in the present invention, the above-mentioned set voltage Vcs is detected, and when the charge voltage Vc exceeds the set voltage Vcs, a charge current corresponding to, for example, a small-sized battery is supplied to the charge terminal 13a. Is what is done. As a result, the charging voltage Vc changes, for example, as shown in FIG. That is, in FIG. 4, the charging voltage Vc once drops immediately after the switching of the charging current. During this period, the detection of -ΔV is prohibited, and the conventional small-sized battery is thereafter connected by the same charging. Battery can be fully charged.

In this case, the charging is performed with a charging current corresponding to, for example, a large-sized battery from the start of charging until the charging voltage Vc is detected to exceed the set voltage Vcs. Time can be reduced.

Therefore, in this device, charging of all the batteries is started with the charging current corresponding to the battery of the maximum capacity to be connected, and when the charging terminal voltage of the battery reaches a predetermined voltage, the value of the charging current is changed. By performing charging with a small size, rapid charging can be favorably performed at low cost, and full charge can be accurately detected.

As a result, in the conventional device, a discriminating mechanism is required for both the battery and the charging device, which leads to an increase in manufacturing cost and the like, and the detection of the full charge requires the detection of a voltage change such as -ΔV or Vpeak. According to the present invention, there is a possibility that the detection may not be performed accurately during the charging of the battery at a low temperature or after a long-term storage, and the battery may not be able to be fully charged. Problems can be solved.

In the above-described apparatus, the control by the microcomputer 18 is performed according to, for example, a flowchart shown in FIG. That is, in FIG. 5, for example, when the commercial AC power is supplied from the power plug 12 and the signal from the battery detection switch 19 detects that the battery is mounted, the process is started. In step [1], the constant current power supply circuit 11 is set to form a charging current suitable for, for example, a large-sized battery, and a control signal during charging is supplied to the gate of the FET 14.

Next, in step [2], it is determined whether or not the charging voltage Vc has exceeded the set voltage Vcs. If not (No), the charging voltage Vc is determined in the following step [3].
It is determined whether a voltage change -ΔV has occurred in c. Here, if there is no voltage change -ΔV in the charging voltage Vc in this state (No), steps [2] and [3] are repeated. When a voltage change -.DELTA.V occurs in the charging voltage Vc (Yes), a control signal for terminating the charging is supplied to the gate of the FET 14 in step [4], and the operation is terminated.

If it is determined in step [2] that the charging voltage Vc has exceeded the set voltage Vcs (Yes),
In step [5], the constant current power supply circuit 11 is set to form a charging current suitable for, for example, a small-sized battery. Further, in step [6], the period during which the charging voltage Vc temporarily decreases immediately after the above-described switching of the charging current (5 to 5).
It is determined whether or not (about 10 minutes) has elapsed. If not (No), steps [2], [5] and [6] are repeated. In step [2], once the detection is performed, the detection result remains unchanged even if the voltage Vc decreases.

If the time has elapsed in step [6] (Yes), the process proceeds to step [3], and thereafter, steps [2], [5], [6], and [3] are repeated. Here, if a voltage change -.DELTA.V occurs in the charging voltage Vc, the determination in step [3] becomes (Yes), and in step [4], a control signal for charging end is supplied to the gate of the FET 14 and the operation is ended (end). .

Thus, in the above-described device, charging of all batteries is started with a charging current corresponding to the battery of the maximum capacity to be connected, and charging is performed when the charging terminal voltage of the battery reaches a predetermined voltage. Charging can be performed with a small current value.

Further, in the above-described device, the FETs 14 and 15 with small loss are used as the switching elements for charging output, but if the charging current is up to about 1 amp,
For example, a device can be formed using a bipolar transistor or a diode for preventing backflow. That is, FIG. 6 shows an example in which a device is formed using a bipolar transistor and a diode.

In FIG. 6, the charging output from the constant current power supply circuit 11 is connected to the emitter / collector of a switching pnp transistor 21 and a positive charging terminal 13a through a diode 22 for preventing backflow. The ground terminal of the constant current power supply circuit 11 is directly connected to the negative charging terminal 13b. Further, an output terminal of a charge control signal from the microcomputer 18 is connected to the base of the npn transistor 23, and the collector of the transistor 23 is connected to the base of the transistor 21.

Otherwise, the configuration is the same as that of FIG. With this, the same operation as the above-described FETs 14 and 15 can be performed. In this way, for example, when the charging current is up to about 1 amp, the present invention can be implemented with a simple configuration as shown in FIG.

According to the charging apparatus described above, a rechargeable battery is connected, and in a device that supplies a controlled current to the battery to perform charging, the charging current has a value corresponding to the maximum capacity of the connected battery. And starts charging of all the batteries at the same time, detects the charging terminal voltage of the battery, and when the detected voltage reaches a predetermined voltage, reduces the value of the charging current to perform charging. In addition to quick charging, it is possible to accurately detect full charge.

According to the charging device of the present invention described above,
Since the current is not switched according to the size of the battery, even a small-sized battery having a low internal resistance can be charged in a shorter time than in the past.

[0037]

Therefore, according to the first aspect of the present invention, charging of all the batteries is started with the charging current corresponding to the battery having the maximum capacity to be connected, and the charging terminal voltage of the batteries reaches a predetermined voltage. In some cases, rapid charging can be performed satisfactorily at a low cost by performing charging by reducing the value of the charging current, and the full charge can be accurately detected.

As a result, in the conventional apparatus, a discriminating mechanism is required for both the battery and the charging apparatus, which leads to an increase in manufacturing cost and the like, and the detection of the full charge requires the detection of a voltage change such as -ΔV or Vpeak. According to the present invention, there is a possibility that the detection may not be performed accurately at the time of charging the battery during low temperature or after long-term storage, and the battery may not be able to be fully charged. The problem can be solved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a charging device to which the present invention is applied.

FIG. 2 is a diagram for explaining the operation.

FIG. 3 is a diagram for explaining the operation.

FIG. 4 is a diagram for explaining the operation.

FIG. 5 is a flowchart for explaining the operation.

FIG. 6 is a configuration diagram of another example of a charging device to which the present invention is applied.

FIG. 7 is a diagram for explaining a conventional device.

FIG. 8 is a diagram for explaining a conventional device.

[Explanation of symbols]

11: constant current power supply circuit, 12: power plug, 13: charging terminal, 14, 15: FET, 16: npn transistor, 17: pnp transistor, 18: microcomputer for control, 19: battery detection switch, 20: trickle resistance

Claims (2)

[Claims] 1. A charging device to which a rechargeable battery is connected and which supplies a controlled current to the battery to perform charging, wherein all of the batteries have a charging current of a value corresponding to the maximum capacity battery to be connected. A charging device that starts charging of the battery, detects a charging terminal voltage of the battery, and performs charging by reducing the value of the charging current when the detected voltage reaches a predetermined voltage. 2. A connection means for a rechargeable battery, a current control means for controlling a charging current supplied to the battery, and a detection means for detecting a charging terminal voltage of the battery, Charging of all batteries is started with a charging current of a value corresponding to the capacity of the battery, and charging is performed by reducing the value of the charging current when the detection voltage reaches a predetermined voltage. Claim 1
The charging device as described.