JPH02254934A - Charging apparatus for storage battery - Google Patents

Abstract

PURPOSE:To prevent an insufficient charge and to cause a battery life not to shorten by correcting a charging voltage according to a battery temperature and by increasing a charging current, when a storage battery is charged appropriately according to the rise and fall of said battery temperature. CONSTITUTION:A battery temperature sensor T is an element, of which the value of resistance has a negative temperature coefficient and a battery upper limit temperature sensor H is an element, which is turned OFF when temperature rises. A charging voltage selection circuit E detects a battery temperature to select a constant voltage value VD and an amplifier circuit G detects the time when a battery voltage exceeds said voltage value VD. A voltage control signal issuing circuit J issues a signal to charge at said constant voltage VD. A charging current lower limit storage circuit K stores that a charging current is minimized, and an amplifier circuit M detects the time when said charging current is higher than a minimum limit. A boosting charge stop signal issuing circuit N issues a signal charging to a trickle charge. A charging current cancel circuit P stops the function of said charging current lower limit storage circuit K and a charging current monitor circuit L.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a charging device for storage batteries that charges at a constant voltage, and is particularly applied to a rapid charging device for sealed nickel-cadmium storage batteries.

Prior art As a conventional example of this type of charging device, for example, Japanese Patent Application Laid-Open No. 49-7
Those described in Publication No. 3634 can be listed. This charging device charges a storage battery with a constant voltage and limits charging when a change in charging current exceeds a predetermined positive value.

Problems to be Solved by the Invention In general, when a storage battery approaches a fully charged state during charging, its temperature begins to rise, and as charging continues, the temperature begins to rise rapidly. Then, the apparent internal resistance decreases, and when constant current charging is performed, the storage battery voltage also decreases accordingly. Furthermore, during constant voltage charging, the charging current increases.

In the conventional technology, as mentioned above, in constant voltage charging, the charging th current increases at the end of charging, and when this change exceeds a certain positive value, the charging is detected and the charging is restricted. This was a convenient charging method because the temperature rise of the storage battery was large and the change in charging current was therefore noticeable.

However, since the storage battery voltage has a negative characteristic with respect to the storage battery temperature, when charging with a constant voltage regardless of the storage battery temperature as in the conventional technology, if the storage battery temperature is low! Since the battery voltage is high, a certain constant voltage of 1V is set from the beginning of charging. , and the charging current decreases from an early stage.
Sometimes the battery became insufficiently charged, or it took a long time to reach a fully charged state. Conversely, when the temperature is high, the storage battery voltage is low, so the voltage is constant at 1V. If the current is not reached, a large current continues to flow, resulting in overcharging, which not only drastically shortens the life of the battery, but also, in the worst case, causes the battery to explode.

There was a risk of explosion.

Means for Solving the Problems The present invention is intended to solve the above-described drawbacks of the prior art. By correcting the value to an appropriate value, the charging current will increase when a certain appropriate charging state is reached, depending on the temperature of the storage battery, and by detecting that point, it will be possible to detect an abnormal state. It is an object of the present invention to provide a charging device for a storage battery that is characterized in that it limits charging extremely well without deviation. Another object of the present invention is to provide a storage battery charging device which is equipped with a storage battery upper limit temperature detector to improve safety and which limits charging when the storage battery temperature becomes abnormally high during charging.

Function: The charging device according to the present invention includes a temperature sensor in the storage battery and adjusts the charging voltage to an appropriate value according to the temperature of the storage battery, so that charging can be controlled extremely well regardless of whether the temperature of the storage battery is high or low. . Additionally, it is equipped with a storage battery upper limit temperature detector and can limit charging when the storage battery temperature becomes abnormally high, allowing safe charging even during ultra-rapid charging.

Example Next, specific examples of the present invention will be described.

FIG. 1 is a block diagram showing an example of the charging device of the present invention. In the figure, A is a power supply circuit, which receives commercial power, transforms it, and further converts it into DC power. B is a sealed nickel-cadmium storage battery (hereinafter referred to as a storage battery) for rapid charging, which is made up of 10 cells connected in series with a rated capacity of 1.28H. C is a charging circuit that can pass a maximum current of 24 A (20 C, that is, a current value 20 times the rated capacity of the storage battery). D is a backflow prevention diode, which is used to prevent current from flowing back from the storage battery to the charging device. R is a current detection resistor. Therefore, the storage battery B is charged in a loop consisting of the power supply circuit A, the charging circuit C1, the backflow prevention diode D, and the current detection resistor R.

1 is a storage battery bag, which is composed of a storage battery B, a storage battery temperature sensor T, and a storage battery upper limit temperature detector H.

The storage battery temperature sensor T is an element whose resistance value has negative temperature characteristics. The storage battery upper limit temperature detector H is an element that is always in an ON state and turns OFF when the temperature rises to 55°C. This element has a differential of 20°C and does not return to the ON state until the temperature drops to 35°C.

After bringing these elements 1 and H into contact with battery B and fixing them with adhesive tape, cover the whole thing (B, T, and H) with a heat shrink tube so that these elements can accurately sense the battery temperature. It is.

2 is a charging voltage control circuit, which includes a charging voltage selection circuit E, a storage battery voltage monitor circuit F, an amplifier circuit G, and a voltage control circuit t11.
It consists of an I signal issuing circuit J.

The charging voltage selection circuit E is for detecting the temperature of the storage battery at the start of charging and selecting a constant voltage of 1Vo commensurate with the temperature. This circuit corrects the temperature of the charging voltage based on the resistance value of the storage battery temperature sensor', and its set value Vo is determined by the following equation.

■ゎ=16.5-0.04X (t-20)
[V] t here; Storage battery temperature [”C] However, if the storage battery temperature is low, the set value (vo) is set to 1 to prevent the charging voltage from becoming abnormally high.
It is set so that it does not rise above 6.8V.

The storage battery voltage monitor circuit F is for monitoring the storage battery voltage. In the amplifier circuit G, the storage battery voltage obtained from the storage battery voltage monitor circuit F is the voltage ■ obtained from the charging voltage selection circuit E. This is a circuit that detects when it exceeds even the smallest value. The voltage control signal issuing circuit J is for receiving the above detection signal from the amplifier circuit G and issuing a signal to the charging circuit C to charge at a constant voltage VD.

3 is a ΔI detection circuit, which detects that a change in charging current exceeds a predetermined positive value.

This circuit includes a current detection resistor R1, a charging current lower limit storage circuit, a charging current monitoring circuit, and an amplifier circuit M.

It consists of a quick charge stop signal issuing circuit N and a charging current detection canceling circuit P. The charging current lower limit storage circuit stores the fact that when the storage battery is charged at a constant voltage of 0, the battery approaches a fully charged state and the charging current becomes minimum. The charging current monitor circuit is for monitoring the charging current. The amplifier circuit M is configured such that the charging current obtained from the charging current monitor circuit is 0.6 A (0.5 C, that is, 0.5 times the rated capacity of the storage battery) than the minimum value obtained from the charging current lower limit storage circuit K. This is a circuit that detects when the value) has become large. The quick charge stop signal issuing circuit N is for receiving a detection signal from the amplifier circuit M and issuing a signal to the charging circuit C to change from quick charging to trickle charging. Note that the trickle charging current is 4 (h
It is set to be g^ (1/30 C). The charging current detection canceling circuit P is a circuit for stopping the functions of the charging current lower limit value storage circuit and the charging current monitoring circuit only for 10 seconds after the start of charging.

This is because when a storage battery has been left unused for a long period of time, the internal resistance at the beginning of charging appears to be abnormally high, and as the charging progresses, it decreases, causing the charging current to increase even though it is not fully charged. be. This is to prevent a quick charge stop signal from being issued in this case. In addition, in order to prevent the storage battery from being exposed to high temperatures, the storage battery upper limit temperature detector H detects that the storage battery temperature has reached 55°C, and the quick charge stop signal issuing circuit N receives this and starts charging. A signal is issued to the charging circuit C to change from quick charging to trickle charging.

Q is a memory clearing circuit, which is used to clear the memories in the charging voltage selection circuit E and the charging current lower limit storage circuit at the start of charging.

When the charging device and storage battery manufactured as described above were combined, the storage battery could be completely charged in about 5 minutes at a storage battery temperature of 10°C to 35°C.

The charging characteristics at a battery temperature of 23°C were as shown in Figure 2.

In addition, as an example of detecting that the charging current has increased, instead of detecting that the charging current has increased by 0.6A from the minimum value, the charging current is sampled every 3 seconds and the value is changed 5 times in a row. It is also possible to issue a signal to the charging circuit C to switch from quick charging to trickle charging when the voltage rises.

In addition, to protect the storage battery, a timer (setting [6 minutes)]
It is also possible to install a circuit to forcibly stop rapid charging and switch to trickle charging.

Effects of the Invention As described above, the charging device according to the present invention has the following effects:
Since the charging voltage value is corrected each time according to the TI battery temperature, it can be charged in a very short time and well over a wide range of battery temperatures.It also has a storage battery upper limit temperature detector for protection, so the storage battery Prevents exposure to abnormally high temperatures. Therefore, when the storage battery is at low temperature as in the past,
It is highly effective as a storage battery charging device because it eliminates the risk of insufficient charging, long charging time, overcharging at high temperatures, rupture, explosion, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the charging device of the present invention;
FIG. 2 is a characteristic diagram of the storage battery voltage, charging current, amount of charge, and storage battery temperature when a storage battery at 23° C. is charged with the charging device of the present invention.

Claims (1)

[Claims] 1. A charging device that charges a storage battery with a constant voltage and limits charging when a change in charging current exceeds a predetermined positive value at the end of charging, the charging device adjusting the charging voltage according to the storage battery temperature. A storage battery charging device characterized by correcting a value. 2. The storage battery charging device according to claim 1, which has a function of limiting charging when the storage battery temperature reaches 40 to 120° C. during charging.