JP2002223529A - Charging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging apparatus for conducting refresh charging in a short time. SOLUTION: The charging apparatus has a charging-current supply section 10 for supplying a secondary battery 20 with a charging current, a battery hysteresis storage section 21 in which the number of the charging of the secondary battery 20 is stored and a control circuit 16 conducting overcharging up to approximately 150% of capacity, by the charging current of approximately 1C from the start of charging as refresh charging in a charging-current supply circuit section 20, when the state in which the secondary battery 20 is not charged even once or in a state in which a fixed number of normal charging has been previously conducted, after preceding refresh charging has been decided from the number of charging stored by the storage section 21. Usability can be improved by refresh-charging the secondary battery 20, without special operations by a user, while the secondary battery can be subjected to refresh charging in a time shorter than in the conventional examples.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device.

[0002]

2. Description of the Related Art In recent years, secondary batteries have been widely used as power sources, and charging devices for charging the secondary batteries have been provided. At normal time, the charging device is
For example, if the capacity of the secondary battery is about 1600 [mAh], normal charging such as supplying a large charging current of about 8 to 9 [A] to the secondary battery and fully charging the secondary battery is repeated.
The full charge refers to a state in which the battery is charged until the amount of charge with respect to the secondary battery capacity (hereinafter referred to as “charge rate”) reaches about 100%.

However, it is generally known that a secondary battery has a so-called memory effect. The memory effect is a phenomenon in which the apparent capacity of a secondary battery is reduced by repeating charging and discharging of the secondary battery shallowly. Even when the secondary battery is fully charged and power is supplied to the load, the load may not be driven for a predetermined time.

If the secondary battery is left for a long time without supplying power to the load, the secondary battery becomes inactive, and the load is applied for a predetermined period of time in the same manner as when a memory effect occurs. In some cases, it cannot be driven.

Therefore, in the conventional charging device, when charging the secondary battery, the secondary battery is once completely discharged and then charged, or the charging rate is about 250 to 300% every predetermined number of times of charging.
By overcharging the secondary battery until the condition is satisfied, the capacity of the secondary battery that has caused a memory effect or has become inactive is recovered. Here, the operation of restoring the capacity of the secondary battery by completely discharging and then charging or overcharging the secondary battery as described above is generally called refresh charging.

[0006] However, as described above, in refresh charging in which the secondary battery is completely discharged and then fully charged,
Since the charger requires a discharge circuit for completely discharging the secondary battery, there has been a problem that the cost of the entire charging device increases and the shape of the charging device increases.

[0007] On the other hand, in the refresh charging by overcharging, the charging device operates at about 8 hours at the start of charging, similarly to the normal charging.
A charging current as large as ９9 [A] is supplied to the secondary battery to rapidly charge the battery until the charging rate becomes about 100%. Thereafter, the charging current is reduced to achieve a charging rate of about 250 by trickle charging.
Overcharge until ~ 300%. Here, the reason why the charging current is reduced is that if the value of the charging current with respect to the capacity of the secondary battery is large, a chemical change or the like in the secondary battery is excessively promoted and it is difficult to overcharge.

However, since trickle charging has a small charging current, it takes a long time (about 2 hours) for refresh charging.
4 hours).

In view of the above, after the above-mentioned rapid charging, while supplying a charging current larger than trickle charging, the value of the charging current is adjusted so that the temperature of the secondary battery, which rises due to charging, is maintained at a predetermined temperature or lower. A variable charger is provided.

[0010]

However, even if the charge current after the quick charge is larger than the charge current for the trickle charge as described above, the charge current is eventually reduced in order to suppress the temperature rise of the secondary battery. As a result, there is a problem that the time for refresh charging the secondary battery is about 12 hours, although it is shorter than that for trickle charging.

An object of the present invention is to solve the above-mentioned problems, and to provide a charging device for performing refresh charging in a short time.

[0012]

In order to achieve the above object, an object of the present invention is to perform normal charging for fully charging a secondary battery and overcharging a secondary battery having a reduced capacity. A charging device that performs refresh charging to recover the capacity of the secondary battery, a charging current supply unit that supplies a charging current to the secondary battery, and a battery history storage unit that stores at least the number of times that the secondary battery has been charged, The charging current supply unit is controlled to perform normal charging, the number of times of charging is stored in the battery history storage unit, and the secondary battery has never been charged from the number of times of charging stored in the battery history storage unit. If it is determined that the state or the state in which the normal charge has already been performed a predetermined number of times since the previous refresh charge was performed, the charging current supply means performs refresh charge for about 1 C from the start of charging. Control means for overcharging up to about 150% of the capacity with the electric current, characterized in that at the time of the first charge of the secondary battery without the user performing a special operation different from the operation for normal charging Or, the secondary battery is refresh-charged every predetermined number of times of charging, thereby improving the usability, and, after performing rapid charging from the start of charging as in the conventional example, charging the secondary battery with a charging current as small as trickle charging. By performing overcharging up to about 150% of the capacity with a charging current of about 1 C from the start of charging, refresh charging can be performed in a shorter time than in the conventional example.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a timer for counting an elapsed time since the last charging, and the control means determines that the elapsed time is equal to or longer than a predetermined time. When the secondary battery is left for a long time and becomes inactive and its capacity is reduced, the secondary battery is refreshed in a short time. Can be charged.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, as shown in FIG. 1, a charger 1 connected to a commercial power supply AC and a secondary battery 2
A device-side charging unit 3 is provided on a device that operates with power from 0 as operating power and supplies a charging current to the secondary battery 20 in cooperation with the charger 1.

The charger 1 is connected to a commercial power supply AC and has an input circuit 11 composed of a transformer for stepping down the commercial power supply voltage.
A primary rectifier circuit 12 for rectifying an AC voltage output from the input circuit 11, a primary winding n1 of a transformer T connected to an output terminal of the primary rectifier circuit 12 via a switching element Q, A drive circuit 13 that operates by being supplied with power from the rectifier circuit 12 and turns on / off the switching element Q is provided.

The device-side charging section 3 includes a secondary winding n2 of the transformer T, a secondary rectifier circuit 14 for rectifying an AC voltage induced in the secondary winding n2, and a power supply circuit 15 from the AC voltage.
And a control circuit 16 including, for example, a microcomputer for controlling the drive circuit 13 of the charger 1. The battery unit 2 including the secondary battery 20 is detachably mounted. I have.

When the above-described device-side charging unit 3 is connected to the charger 1, the transformer T of the charger 1 and the device-side charging unit 3
From the secondary winding n2 and the secondary side rectifier circuit 14 to the charging current supply unit 10 for supplying the charging current of a magnitude corresponding to the ON / OFF cycle of the switching element Q to the secondary battery 20 of the battery unit 2. Is configured.

The battery section 2 has a history including the number of times of charging of the secondary battery 20 counted by the control circuit 16 and the date and time of charging specified by the internal clock provided in the control circuit 16. A battery history storage unit 21 for storing data is provided.

Here, the control circuit 16 compares the date and time at which the previous charging was performed in the history data of the battery history storage unit 21 with the current date and time of the internal clock, and determines whether the battery has been charged last time. A timer is provided for counting elapsed time.

When the device side charging unit 3 is connected to the charger 1, the control circuit 16
5 is started by the electric power supplied through the power supply 5, and the history data is read from the battery history storage unit 21. The control circuit 16 determines from the read history data that the rechargeable battery 20 has been charged last time, that the number of times of charging has not reached the predetermined number, and counts the time from the read history data. It is also determined whether or not the elapsed time from the previous charging is equal to or longer than a predetermined time by using the means. If it is determined that the predetermined time has not been reached, the switching element Q is turned on / off at a predetermined cycle. By controlling the drive circuit 13 to turn off,
The charging current supply unit 10 is caused to perform normal charging. In the normal charging performed at this time, similarly to the conventional example, the charging current supply unit 1
For example, when the capacity of the secondary battery 20 is about 1
If it is 600 [mAh], a charging current of about 8 to 9 [A] is supplied.

On the other hand, based on the read history data, the control circuit 16 determines that the secondary battery 20 has not been charged at all,
When it is determined that the normal charging as described above has already been performed, for example, 50 times, and the time elapsed since the previous charging was performed using the time counting means from the read history data is a predetermined time. When it is determined that the above is the case, the drive circuit 13 is controlled to vary the ON / OFF cycle of the switching element Q, so that the charging current supply unit 10 performs refresh charging. In the refresh charging performed at this time, the charging current supplied to the secondary battery 20 is about 1 C, and the secondary battery 20 is overcharged to a charging rate of 150%.

Here, C indicates the magnitude of the charging current, and 1C is a current value of 1.7 [A] when the capacity of the secondary battery 20 is, for example, 1700 [mAh]. Therefore, if it is 2000 [mAh], the current value is 2.0 [A].

As described above, the control circuit 16 controls the drive circuit 13 of the charging current supply unit 10 to perform normal charging,
The above-described history data is stored in the battery history storage unit 21, and the charging current supply unit 10 performs refresh charging according to the history data in the battery history storage unit 21.

As a result, the present embodiment does not allow the user to perform a special operation different from the operation for performing the normal charging, and further allows the secondary battery 20 to be further charged at the time of the initial charging of the secondary battery 20 or every predetermined number of times. When the battery is left in an inactive state for a long time and its capacity is reduced,
Can be refresh charged to improve usability.

Further, in the present embodiment, as shown in FIG. 2, for example, overcharging is performed until the charging rate reaches close to 300% as in the conventional example, and the charging is performed in a shorter time than a charging device that performs refresh charging. Refresh charging can be performed.

In the conventional charging device for overcharging by trickle charging, as shown by a in FIG. 2, a large charging current flows from the start of charging, and after about 15 minutes (about 0.25 hours).
Then, rapid charging is performed so that the charging rate A of the secondary battery reaches about 100%, and then trickle charging is performed, and the charging rate A gradually increases. After about 24 hours, the charging rate A becomes 300.
%. In addition, in the conventional charging device that performs overcharging by performing temperature control, a large charging current flows from the start of charging, as shown in FIG.
After a minute, rapid charging is performed such that the charging rate A of the secondary battery reaches about 100%, and thereafter, the value of the charging current is reduced, but the value is set to be larger than the value of the charging current for trickle charging. Have been. As a result, the charging rate A increases earlier than the case shown in a, but when the charging rate A increases, the temperature of the secondary battery also increases, and when the temperature of the secondary battery reaches a predetermined temperature, The value of the charging current can be further reduced so that the temperature does not exceed this. as a result,
About 1 hour after the start of charging, the charging rate A gradually increases, as in the case shown in a.
Reaches nearly 300%.

However, in this embodiment, as shown by c in FIG. 2, the charger 1 charges the secondary battery 20 with a charging current of about 1 C without performing rapid charging as in the conventional example from the start of charging. Therefore, the time required for the charging rate A to reach about 100% is slower than in the conventional example, but the charging rate A is about 150%.
% Can be shortened to about 1.5 hours as compared with the above-described conventional example. That is, since the value of the charging current of about 1C is larger than the value of the charging current after the rapid charging of the conventional example, the time until the charging rate A becomes 150% can be shortened. Further, in the present embodiment, since charging is performed with a small charging current of about 1 C without performing rapid charging from the start of charging, the stress applied to the secondary battery 20 is suppressed, and the charging rate A is 150% smaller than the conventional example, and the secondary battery 20 is charged. The battery 20 can be brought into a state where the capacity has been recovered to substantially the same level as in the conventional example. Moreover, in the present embodiment, as described above, the time required for the refresh charge is sufficiently reduced as compared with the conventional example, so that the temperature rise of the secondary battery 20 is suppressed without changing the charging current unlike the conventional example. You can do it.

[0028]

According to the first aspect of the present invention, the normal charging for fully charging the secondary battery is performed, and the refresh charging for restoring the capacity of the secondary battery by overcharging the secondary battery with reduced capacity is performed. A charging device, comprising: charging current supply means for supplying a charging current to a secondary battery; a battery history storage unit for storing at least the number of times of charging of the secondary battery; and normal charging by controlling the charging current supply means. At the same time, the number of times of charging is stored in the battery history storage unit, and the number of times of charging stored in the battery history storage unit indicates that the secondary battery has not been charged at all or has been refreshed since the previous refresh charging was performed. If it is determined that the normal charging has been performed a predetermined number of times, the charging current supply means performs refresh charging as a refreshing charge.
% Overcharging up to the%, the user does not perform a special operation different from the operation of performing normal charging by the battery history storage unit and the control unit at the time of initial charging of the secondary battery, or The rechargeable battery is refresh-charged every predetermined number of times to improve the usability. In addition to the rapid charging from the start of charging as in the conventional example, a small charging current such as trickle charge is supplied to the rechargeable battery. About 1C from the start of charging
By overcharging to about 150% of the capacity with the charging current, refresh charging can be performed in a shorter time than in the conventional example.

According to a second aspect of the present invention, there is provided a timer for counting the time elapsed since the last charging, and the control means determines whether the elapsed time is longer than a predetermined time. In this case, the secondary battery can be refresh-charged in a short time even when the secondary battery is left inactive for a long time and becomes inactive and its capacity is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic circuit block diagram showing a first embodiment.

FIG. 2 is a comparison diagram with a conventional example for explaining the operation of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charger 2 Battery part 3 Equipment side charge part 11 Input circuit 12 Primary side rectification circuit 13 Drive circuit 14 Secondary side rectification circuit 15 Power supply circuit 16 Control circuit 20 Secondary battery 21 Battery history storage part Q Switching element T transformer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G003 AA01 BA01 CA01 CC02 GA01 GB04 GC04 GC05 5H030 AA01 AS18 BB01 DD06 FF41 FF51 FF52 FF67

Claims (2)

[Claims] 1. A charging device for performing normal charging for fully charging a secondary battery and performing refresh charging for restoring the capacity of the secondary battery by overcharging the secondary battery with reduced capacity, comprising: A charging current supply unit for supplying a charging current to a secondary battery, a battery history storage unit for storing at least the number of times of charging of the secondary battery, and a normal charging operation performed by controlling the charging current supply unit; The number of times of charging is stored in the battery history storage unit, and a predetermined number of times of normal charging has already been performed since the secondary battery has never been charged or since the last refresh charging was performed. When it is determined that the battery is in a charged state, the charging current supply means performs overcharging to about 150% of the capacity with a charging current of about 1 C from the start of charging as refresh charging. A charging device comprising: 2. A time counting means for counting an elapsed time from the previous charging is performed, and when it is determined that the elapsed time is equal to or longer than a predetermined time, the control means performs refresh charging to the charging current supply means. The charging device according to claim 1, wherein the charging device is operated.