JPH1066278A - Charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a charging device by which a secondary battery is charged properly without being influenced by a change in the temperature of the battery due to a change in the ambient temperature of a battery pack by a method wherein the remaining capacity, of the secondary battery, computed on the basis of a charging and discharge current detection value is at a set value or higher and a charging operation is stopped when the temperature rise rate of the secondary battery is at a prescribed value or higher. SOLUTION: A battery-temperature detection means 5 and a charging-and-discharge- current detection means 10 are built in a battery pack 2. Then, the temperature detection means 5 outputs a charging-finish signal when the temperature rise rate of a secondary battery 4 reaches a prescribed value. On the other hand, on the basis of detection data on a charging and discharge current by the charging-and-discharge- current detection means 10, a remaining-capacity detection means 9 computes the remaining capacity of the secondary battery 4, and it outputs a charging finish signal when its value is at a set value or higher (a fully charged state). At this time, a charging control means 6 outputs a charging stop signal to a power supply 3 only when both the temperature detection means 5 and the remaining-capacity detection means 9 output a charging finish signal, and it finishes the charging operation of the secondary battery 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack containing a plurality of secondary batteries and a charger for supplying a charging current to the battery pack. The present invention relates to a charging device provided with means for detecting a remaining capacity.

[0002]

2. Description of the Related Art In recent years, a secondary battery used as a power source for a portable device or a mobile body is charged by a so-called quick charge, which is supplied with a constant current and is completed in about several hours. Often. When performing this rapid charging, it is necessary to accurately grasp the state of charge of the secondary battery and to terminate charging when the secondary battery is fully charged in order to prevent the secondary battery from being overcharged. is there.

As a method of detecting the end point of the charging,
A method of detecting a point at which the battery voltage has risen to a specified value or a method of detecting a point at which the battery voltage has dropped by a set value from the peak value of the battery voltage has been adopted. In particular, in the nickel-metal hydride battery, a method of detecting a rate of increase in battery temperature per unit time and detecting a point at which the rate of increase reaches a predetermined set value is used.

Hereinafter, the configuration and operation of a known charging device having a function of detecting a rate of change in temperature rise of a secondary battery (hereinafter, referred to as a temperature rise rate) will be described with reference to the drawings.

FIG. 3 is a configuration diagram of a known charging device.
1 is a charger, 2 is a battery pack, and the charging device is composed of the charger 1 and the battery pack 2. When charging the battery pack 2, the battery pack 2 is connected to the charger 1 and receives power supply. After charging is completed, Charger 1
The battery pack 2 removed from the battery pack is mounted on a device such as a mobile phone, which is a load, and supplies power to these devices.
Reference numeral 3 denotes a power supply for supplying a charging current. Reference numeral 4 denotes a chargeable / dischargeable secondary battery incorporated in the battery pack 2, and has a configuration in which, for example, a plurality of nickel-metal hydride batteries are connected in series. The battery pack 2 has a built-in temperature detecting means 5 for detecting the temperature of the secondary battery.

On the other hand, the charger 1 is provided with charge control means for controlling the charge current supplied from the power supply 3 to the battery pack 2 based on the temperature signal output from the temperature detection means 5. ing. The charger 1 and the battery pack 2 are connected via terminals. Reference numeral 7 denotes a charging connection terminal, and 8 denotes a temperature detection terminal. These terminals connect the power supply 3 to the charging path of the secondary battery 4 when the charger 1 and the battery pack 2 are connected, and the temperature detection means and the charging. This is a terminal for connection with the control means.

Next, the operation of the charging device will be described.
When charging the secondary battery 4, the battery pack 2 is
The temperature signal indicating the secondary battery temperature detected by the battery temperature detection means 5 is input to the charge control means 6 via the temperature detection terminal 8. When detecting the signal input, the charging control means 6 outputs a charging output signal for starting charging to the power supply 3 and starts charging the secondary battery 4.

FIG. 4 shows a change over time of a battery voltage, a battery temperature, and a charging current during charging of a secondary battery. As charging proceeds, both the battery voltage and the battery temperature increase. The state of the temperature change of the secondary battery 4 is input from the battery temperature detection unit 5 to the charge control unit 6.

At the end of charging as charging progresses, the battery temperature rises compared to the initial stage of charging, and the rate of temperature rise per unit time (ΔT / Δt) increases. When the temperature detecting means 5 detects that the rate of increase has reached a predetermined value, the charging control means 6 outputs a charge stop signal for stopping the current to the power source 3 and the secondary battery 4 is incorporated. The supply of the charging current to the battery pack is stopped, and the charging is terminated.

[0010]

However, in the charging device having the above configuration, there is a possibility that the temperature detecting means may malfunction due to a sudden change in the ambient temperature before or during charging.

For example, when a portable device is brought into a warm room from a cold place, the battery pack 2 attached to the portable device is taken.
The temperature conditions of the environment in which the is placed change rapidly and drastically.
Immediately after this, when the battery pack is connected to the charger and charging is started, the temperature of the secondary battery housed in the battery pack rapidly rises due to a change in the ambient temperature.

As is apparent from the graph of FIG. 5 showing the change in the battery temperature with respect to the charging time, when the ambient temperature of the battery pack 2 suddenly changes from a low temperature to a high temperature, the secondary battery is changed due to the change in the ambient temperature. 4 rises, and the temperature detecting means 5 detects a change in the battery temperature caused by the change in the ambient temperature. For this reason, before detecting the temperature rise change of the secondary battery 4 at the end of charging, which should be detected as indicated by the dotted line, the charging control means 6 malfunctions, and the secondary battery in the battery pack becomes fully charged. Before the charging device stops.

Conversely, when the ambient temperature at which the secondary battery 4 is placed changes from a high-temperature environment to a low-temperature environment, the battery temperature of the secondary battery 4 decreases with the change in the ambient temperature. I do. At this time, as the battery temperature decreases, the rate of increase of the battery temperature becomes smaller than that in the normal state. That is, the temperature increase rate of the battery does not reach the specified value due to a change in the ambient temperature. Therefore, even though the battery is fully charged,
The charging control means 6 continues charging, and the secondary battery may be in an overcharged state.

As described above, a change in the battery temperature due to a change in the ambient temperature of the battery pack causes the battery to change to a non-charged state or an overcharged state. Therefore, it is necessary to monitor the charged state without being affected by the temperature change. There was a problem that there is. An object of the present invention is to provide a charging device that suppresses the occurrence of excessive or insufficient charging capacity of a secondary battery and appropriately detects a fully charged state.

[0015]

To achieve this object, a charging device according to the present invention comprises a plurality of chargeable / dischargeable secondary batteries,
A battery pack containing temperature detecting means for detecting the temperature of the secondary battery and charging / discharging current detecting means for detecting the charging / discharging current of the secondary battery; and a charging current connected to the battery pack to charge the secondary battery. The battery charger includes a power supply to be supplied, charge control means for controlling the charge current, and remaining capacity detection means for calculating the capacity of the secondary battery output from the charge / discharge current detection means.

The remaining capacity detecting means detects the remaining capacity of the secondary battery from the charging / discharging current value output from the charging / discharging current detecting means, and the charging controlling means detects the remaining capacity detected by the capacity detecting means. When the temperature rise rate detected by the temperature detecting means is equal to or higher than a predetermined set value and is equal to or higher than a specified value, a signal to stop charging is output to the power supply,
This is to stop charging.

With this configuration, by accumulating the amount of charge of the secondary battery, it is possible to prevent malfunction of the charge control means and appropriately charge the secondary battery without excessive or insufficient charging.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a charging device according to the present invention. In FIG. 1, those having the same configuration as the above-mentioned known charging device and those having the same function are denoted by the same reference numerals.

The charging device of the present invention comprises a charger 1 and a battery pack 2 as in the above-described conventional example. The charging current supplied from the power source 3 to the secondary battery 4 is controlled by the charging control means 6. Controlled. The temperature detection means incorporated in the battery pack detects the temperature of the secondary battery 4 and outputs the detection result to the charge control means 6 via the temperature detection terminal 8.

Reference numeral 9 denotes remaining capacity detection means for calculating the remaining capacity of the secondary battery based on the charge / discharge current flowing through the charge / discharge path. Reference numeral 10 denotes a charging / discharging current detecting means built in the battery pack 2, and measures and detects a charging / discharging current flowing through a charging / discharging path in the battery pack. The detected current value is output to the remaining capacity detection circuit 9 via the current detection terminal 11, and the capacity of the secondary battery is calculated based on this value.

As described above, the charger 1 and the battery pack 2
The operation of the charging device according to the present invention, which is configured from the above, will be described.

When charging the secondary battery 4, when the battery pack 2 is attached to the charger 1, a signal indicating the temperature of the secondary battery detected by the temperature detecting means 5 is input to the charging control means 6. Is done. The charging / discharging current detecting means 10 includes:
A charging current supplied from the charger to the battery pack and a discharging current supplied to the device by the battery pack are detected, and the detection result is output via the current detection terminal 11. At the time of charging, the remaining capacity detecting means 9 constituting the charger 1
Calculates the capacity of the secondary battery 4 based on the output current signal. The calculated result is stored in the remaining capacity detecting means 9.
Is output to the charge control circuit 6 as a capacity calculation signal.

On the other hand, when the battery pack 2 is connected to the device, a signal including the value of the discharge current detected by the charging / discharging current detecting means 10 is output from the current detection terminal 11, and the device outputs this signal. The remaining capacity of the secondary battery is calculated from the dischargeable battery capacity of the secondary battery 4, and based on the result, information useful for the user of the device, for example, an estimate of the available time of the device, etc. indicate.

When the charge control means 6 detects the temperature detection signal from the temperature detection means 5 and the capacity calculation signal from the remaining capacity detection means 9, it determines that these two detection means are functioning normally. Further, the charge control means 6 instructs the power supply 3 to start supplying current to the secondary battery 4,
The charger 1 starts charging the battery pack 2.

FIG. 2 shows changes over time in battery voltage, battery temperature, charge current, and battery capacity when a secondary battery pack is charged using the charging device of the present invention.

The supply of the charging current to the secondary battery 4 is started, and as the charging proceeds, the voltage, temperature and capacity of the secondary battery each begin to increase gradually. Charge control means 6
, The change in the temperature of the secondary battery 4 is input from the battery temperature detecting means 5, and the charge control means 6 refers to the temperature change and the battery capacity calculated by the remaining capacity detecting means 9. 4 is controlled.

If the ambient temperature of the battery pack 2 fluctuates during charging, the battery pack 2 is stored inside the battery pack, for example, as the ambient temperature of the battery pack 2 rises due to being brought into the room from a low-temperature environment. The temperature of the rechargeable battery changes rapidly. At this time, the battery temperature detected by the battery temperature detecting means also increases, and the temperature rise rate increases. The temperature detection means 5 outputs to the charge control means 6 that the temperature rise rate has reached a specified value. But,
The remaining capacity detecting means 9 for monitoring the state of charge of the secondary battery 4 from the charging current flowing through the charging / discharging path does not output a charge completion signal indicating that the secondary battery is fully charged to the charging control means 6. The charge control unit 6 determines that the amount of electricity supplied to the secondary battery has not reached the capacity of the secondary battery. It is determined that the temperature has risen, and charging of the battery pack 2 is continued.

As the charging progresses, and the battery approaches the end of charging, the temperature of the battery rapidly changes, and the rate of temperature rise per unit time increases. As in the conventional example, when the temperature rise rate reaches the specified value, the temperature detecting means 5 increases the temperature rise rate to the specified value, and sends a charge completion signal to the charge control means 6. At this time, based on the detection data of the charging / discharging current by the charging / discharging current detecting means 10, the remaining capacity detecting means determines whether the rechargeable battery 4
Is calculated to determine the state of charge of the secondary battery. If the calculated result is not less than a certain value (full charge capacity), a charge completion signal is input from the remaining capacity detection means 6 to the charge control means 6. That is, the charging control unit 6 outputs a charging stop signal to the power supply 3 only when each of the temperature detecting unit 5 and the remaining capacity detecting unit 9 outputs a charge completion signal, and charges the secondary battery. To end.

As described above, according to the present embodiment, the temperature and the battery capacity of the secondary battery are detected, and the charging is controlled based on these values. Malfunction of temperature detection due to the fluctuation can be eliminated, and the secondary battery can be appropriately charged.

[0031]

As described above, in the charging apparatus according to the present invention, the signal indicating the remaining capacity of the secondary battery is equal to or higher than a certain value, and the temperature increase rate output from the temperature detecting means is equal to or higher than a certain value. At this time, by providing a signal for stopping charging to the power source and providing charging control means for stopping charging, the secondary battery can be appropriately charged by preventing overcharging.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a charging device according to the present invention.

FIG. 2 is a diagram showing a change over time of a battery temperature and a battery capacity in the charging device of the present invention.

FIG. 3 is a configuration diagram of a known charging device.

FIG. 4 is a diagram showing changes over time in battery voltage, battery temperature, and charging current during charging.

FIG. 5 is a diagram showing a change in battery temperature with respect to a charging time;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charger 2 Battery pack 3 Power supply 4 Secondary battery 5 Battery temperature detection means 6 Charge control means 9 Remaining capacity detection means 10 Charge / discharge current detection means

Claims (1)

[Claims] A battery pack accommodating a plurality of chargeable / dischargeable secondary batteries, temperature detection means for detecting the temperature of the secondary batteries, and charge / discharge current detection means for detecting a charge / discharge current of the secondary batteries; A power supply connected to the battery pack for supplying a charging current to the secondary battery, a charge control means for controlling the charging current, and a remaining capacity detection for calculating a capacity of the secondary battery output from the charge / discharge current detecting means A charging device comprising a charger having means for ending the charging of the secondary battery when a rate of increase in the temperature of the secondary battery detected by the temperature detecting means per unit time reaches a predetermined value. Wherein the remaining capacity detection means detects the remaining capacity of the secondary battery from the charge / discharge current value output from the charge / discharge current detection means, and the charge control means detects the remaining capacity detected by the capacity detection means But Located above defined et al was set value, and when the detected temperature increase rate is above a specified value by the temperature detecting means, outputs a signal to stop charging to the power supply, the charging device stops the charging.