JP2003079065A - Charging method for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with charging by a simple method under various conditions in charging of a secondary battery. SOLUTION: A control means 3 operates a timer 5, upon detecting voltage detected by a voltage detection means 2, or a peak value of temperature detected by a temperature detection means 8, and after a certain time, switches the charging method over to a trickle charging mode or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of charging a secondary battery, which is capable of efficiently charging the secondary battery with a simple circuit and control method without overcharging. Is.

[0002]

2. Description of the Related Art In the prior art, secondary batteries such as nickel-hydrogen batteries and nickel-cadmium batteries have different charging characteristics because they have different chemical reactions.
Therefore, the charger only for those batteries was needed. Recently, a charger compatible with a plurality of secondary batteries has appeared, and the convenience of the user is improved.

[0003]

In the above-mentioned conventional techniques, the control circuit is complicated to cope with a plurality of secondary batteries, which is expensive. In addition, since the charging characteristics of the secondary battery change depending on the ambient temperature, the method of detecting full charge by observing the fluctuation of the terminal voltage of the battery differs in the way the voltage drops from the peak voltage value. There was a problem that became a state. In addition, if control is performed to avoid such a state, there is a problem in that the charge amount does not reach 100% depending on the temperature, and the characteristics of the secondary battery cannot be fully utilized. However, it was not sufficient in terms of efficient use of energy, shortening of charging time, and protection of batteries.

[0004]

In order to solve this problem, the present invention, when detecting a sign of full charge, causes the control means to start a timer and change the charging method. This allows
Even if the charging characteristics of the secondary battery change due to changes in ambient temperature, almost the same amount of charge can be obtained. Further, by specifying the type of the secondary battery from the temperature change and determining the charging current for trickle charging, trickle charging suitable for each secondary battery is possible.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The mode of carrying out the present invention will be described in detail by additionally describing the action and effect of the invention described in each claim for achieving the object of the present invention and adding an example. And

According to a first aspect of the present invention, in the secondary battery charging system, the secondary battery is charged with a constant current from the power supply source, and the charge control means is the peak of the terminal voltage of the secondary battery. When the value is detected and the peak value is detected, the charging control means activates a timer, and when the timer measures a preset time, the charging method is switched to change the charging method. When the ambient temperature is high, the voltage drop value at the end of charging cannot be detected and the charging method can be switched without overcharging.

According to a second aspect of the present invention, in the secondary battery charging system, the secondary battery is charged with a constant current from the power supply source, and the charging control means detects the temperature of the battery to be charged, and the peak value is reached. Is detected, the charging control means activates a timer, and when the timer measures a preset time, the charging method of the secondary battery is switched and the charging method is changed according to the ambient temperature and charging current during charging. Even if the temperature curve of the battery to be charged is different, the charging method can be switched without overcharging.

According to a third aspect of the present invention, in the secondary battery charging system, the secondary battery is charged with a constant current from the power supply source, and the charging control means measures the temperature of the battery to be charged at regular intervals. However, it is a method of charging the secondary battery that calculates the temperature difference and switches the charging method when the temperature difference exceeds a preset value, and it is possible to quickly detect full charge. .

The invention according to claim 4 is the method for charging a secondary battery according to claim 3, which has a plurality of preset values and can specify the type of the battery. It is possible to support various types of secondary batteries, and it is possible to perform control with the optimal charging method for each secondary battery.

According to a fifth aspect of the present invention, there is provided a method for charging a secondary battery according to any one of the first to third aspects, in which charging is performed in a trickle charge mode after switching the charging method. It is possible to maintain the fully charged state by performing trickle charging that maintains the fully charged state without causing performance deterioration of the secondary battery.

According to a sixth aspect of the present invention, there is provided a secondary battery charging method according to the fourth or fifth aspect, wherein the charging current charged in the trickle charge mode is determined according to the type of the battery. It is possible to change the current value in the trickle charge mode according to the type.

[0012]

EXAMPLES Next, examples of the present invention will be described.

(Embodiment) FIG. 1 is a block diagram of a charging circuit in an embodiment of the invention described in claims 1 to 6 of the present invention.

The power supply source 1 supplies power to the battery 6 to be charged. It is desirable that the power supply source 1 supply power to the battery 6 to be charged at a constant current. As the power supply source 1, AC power may be stepped down by a transformer for rectification, or AC power may be rectified into DC and the DC power may be switched and supplied. Further, a DC power source such as a solar power generation or a fuel cell may be used as the power supply source 1.

The voltage detecting means 2 detects the voltage of the battery 6 to be charged.

The charging control means 3 controls the switching element 4 and controls the charging of the battery 6 to be charged.
The charging control unit 3 controls the switching element 4 to open and close the switch, thereby supplying or stopping the power of the power supply source 1. When the power supply source 1 cannot output a constant current, the charging control means 3 may control the switching device 4 to a constant current. In this case, since the charging current can be freely controlled, it is possible to cope with various charging patterns such as switching between quick charging and standard charging and supplementary charging and trickle charging.

The switching element 4 may be a semiconductor power element or a mechanical switch such as a relay.

The timer 5 is for measuring the charging time. The timer 5 is controlled by the charge control means 3 to start and stop counting, and the value counted by the timer 5 is taken into the charge control means 3 as data and used as control information for the switching element 4. It is what is done.

The battery 6 to be charged receives electric power from the electric power supply source 1 and stores the electric power. The battery 6 to be charged is a secondary battery. The types of the secondary battery are nickel hydrogen battery, nickel cadmium battery, lithium ion battery,
Although lead batteries are often used, other types of secondary batteries may be used.

The temperature detecting element 7 is an element for measuring the temperature of the battery 6 to be charged. The temperature detecting element 7 may be a couple wire or the like, but may be other than that.

The temperature detecting means 8 detects the temperature of the signal from the temperature detecting element 7. The charging characteristics of the secondary battery are greatly affected by the ambient temperature, and the charged battery 6
It also generates heat. Therefore, the control means 3 needs to control the charging according to the temperature detected by the temperature detection element 7.

According to the first aspect of the invention, in the secondary battery charging system, the battery 6 to be charged is charged from the power supply source 1 at a constant current. At that time, the charging control means 3 measures the terminal voltage of the battery 6 to be charged, and the charging control means 3 detects the peak value of the terminal voltage. This is because the secondary battery has the characteristic that the terminal voltage drops when it is fully charged, and thus the full charge is detected by detecting the voltage drop.

However, the conventional method of detecting the drop of the terminal voltage has a problem. As shown in FIG. 2, a change in the terminal voltage during charging of the secondary battery draws different curves such as a curve A and a curve B due to changes in the ambient temperature. Therefore, if the drop of the terminal voltage is set in advance by a constant, depending on the ambient temperature, the
In some cases, ΔV can be detected, but on the contrary, there is a problem that −ΔV cannot be detected easily and the battery is overcharged.
That is, in the case of the charging characteristic like the curve A, −ΔV can be detected immediately, but in the case of the charging characteristic like the curve B, −ΔV cannot be detected and the battery is overcharged in some cases.
Therefore, the -ΔV voltage detection method and other control methods have to be used together.

According to the present invention, when the peak value of the terminal voltage is detected, the charging control means 3 activates the timer 5, and when the timer 5 measures a preset time, the charging method is switched to change the charging method. And As a result, the charging is switched by the timer instead of detecting the −ΔV voltage after the peak value, so that it is not necessary to detect −ΔV and the terminal voltage of the battery 6 to be charged is almost full even if it draws any curve. It becomes possible to switch the charging by charging.

Here, the operation timing of the timer 5 is set at the time of detecting the voltage peak point, because if the timer is operated at the start of charging, the remaining capacity of the battery 6 to be charged is large, and-
This is because the battery 6 to be charged is overcharged when it takes time to detect ΔV.

With the charging method according to the present invention, charging can be completed without overcharging the battery 6 to be charged and with a little charge when the remaining capacity is large. The convenience of the user of No. 6 is improved.

The invention according to claim 2 is the charging control means 3
Detects the temperature of the battery to be charged by the temperature detecting means 8,
When the temperature exceeds a preset temperature, the charging control means 3
Activates timer 5, and switches the charging method when the timer measures a preset time.

As shown in FIG. 3, when a different curve is drawn depending on the characteristics of the battery 6 to be charged, if a temperature change −ΔT is detected from the peak temperature, if a constant is set in advance,
Depending on the curve drawn by the battery 6 to be charged, there may be a case where −ΔT can be detected, and conversely, it is difficult to detect −ΔV, resulting in overcharging.

Therefore, similarly to the first aspect of the invention, the overcharge can be prevented by operating the timer 5 when the peak value is detected and switching the charging method after a fixed time.

According to a third aspect of the present invention, the charging control means measures the temperature of the battery to be charged at regular intervals, calculates the temperature difference, and when the temperature difference exceeds a preset value. Change the charging method. This is because depending on the type of secondary battery, the temperature rises abruptly when fully charged, so by calculating the temperature difference at regular intervals, it is detected whether or not the temperature difference exceeds the preset value. . As a result, overcharge can be prevented.

The invention according to claim 4 has a plurality of preset values and specifies the type of battery. Since the characteristics differ depending on the type of the battery 6 to be charged, the tendency of temperature change after full charge is different. Therefore, it is possible to detect it by a plurality of setting values and specify what kind of secondary battery it is. By specifying the type of the secondary battery, the control method after switching the charging method can be changed according to the characteristics of each secondary battery.

According to the fifth and sixth aspects of the present invention, charging is performed in the trickle charging mode after switching the charging method. Trickle charging is charging that compensates for self-discharge after completion of charging. As a result, the battery 6 to be charged can be surely brought into a fully charged state. The charging current in the trickle charge mode needs to be changed depending on the type of the secondary battery. Therefore, it is necessary to specify the type of the secondary battery, but it is possible to specify the type according to the invention of claim 4.

[0033]

As described above, according to the first aspect of the present invention, in the charging system for a secondary battery, the secondary battery is charged with a constant current from the power supply source, and the charging control means uses the peak value of the terminal voltage of the secondary battery. When the peak value is detected, the charging control means activates the timer, and when the timer measures a preset time, the charging method is to switch the charging method of the secondary battery. When the ambient temperature is high, the voltage drop value at the end of charging cannot be detected and the charging method can be switched without overcharging.

According to a second aspect of the present invention, in a secondary battery charging system, the secondary battery is charged with a constant current from a power supply source,
The charging control means detects the temperature of the battery to be charged, and when the peak value is detected, the charging control means activates a timer, and when the timer measures a preset time, the charging method is switched to change the charging method. Therefore, even if the temperature curve of the battery to be charged differs depending on the ambient temperature and the charging current during charging, the charging method can be switched without overcharging.

According to a third aspect of the present invention, in a secondary battery charging system, the secondary battery is charged with a constant current from a power supply source,
The charge control means measures the temperature of the battery to be charged at regular intervals, calculates the temperature difference, and switches the charging method when the temperature difference exceeds a preset value. It is possible to detect the full charge quickly.

Claim 4 has a plurality of preset values,
The method for charging a secondary battery according to claim 3, which enables identification of the type of battery, and is capable of supporting a plurality of types of secondary batteries. Control is possible with an optimal charging method.

A fifth aspect of the present invention is the method for charging a secondary battery according to any one of the first to third aspects, in which charging is performed in a trickle charge mode after switching the charging method. It is possible to maintain the fully charged state by performing trickle charging that maintains the fully charged state without causing deterioration.

A sixth aspect of the present invention is the method for charging a secondary battery according to the fourth or fifth aspect, in which the charging current to be charged in the trickle charge mode is determined according to the type of battery. It is possible to change the current value in the trickle charge mode.

[Brief description of drawings]

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

FIG. 2 is a diagram showing charge capacity and terminal voltage characteristics during constant current charging of a secondary battery.

FIG. 3 is a diagram showing charging capacity and battery temperature characteristics during constant current charging of a secondary battery.

FIG. 4 is a diagram showing charging capacity and battery temperature characteristics during constant current charging of a secondary battery.

[Explanation of symbols]

1 power supply 2 Voltage detection means 3 Charge control means 4 timer 5 Temperature detection means 6 Charged battery 7 Temperature detection element 8 Temperature detection means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Sadahira             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5G003 AA01 BA01 CA02 CA15 CB01                       CC02 GC04                 5H030 AA03 AS20 BB03 FF22 FF43                       FF52

Claims (6)

[Claims] 1. A rechargeable battery charging system, wherein a rechargeable battery is charged with a constant current from a power supply source, and a charge control means detects a peak value of a terminal voltage of the rechargeable battery, and the peak value is detected. Then, the charging control means activates the timer, and switches the charging method when the timer measures a preset time. 2. A rechargeable battery charging system, wherein a rechargeable battery is charged with a constant current from a power supply source, and a charging control means detects the temperature of a battery to be charged, and when a peak value is detected, charging is performed. The control means actuates a timer, and switches the charging method when the timer measures a preset time. 3. A rechargeable battery charging system, wherein a rechargeable battery is charged with a constant current from a power supply source, and a charge control means measures the temperature of a battery to be charged at regular intervals and calculates the temperature difference. The charging method of the secondary battery, which switches the charging method when the temperature difference exceeds a preset value. 4. The method of charging a secondary battery according to claim 3, wherein a plurality of preset values are provided, and the type of battery can be specified. 5. The method of charging a secondary battery according to claim 1, wherein charging is performed in a trickle charge mode after switching the charging method. 6. The method of charging a secondary battery according to claim 4, wherein the charging current charged in the trickle charge mode is determined according to the type of battery.