JPS62163531A - Charger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a charging device for a storage battery, and more particularly to a quick charging device for a sealed nickel-cadmium storage battery.

PRIOR ART AND THEIR PROBLEMS Various charging devices are known for properly performing rapid charging of sealed nickel-cadmium storage batteries. For example, the device described in Japanese Patent Application Laid-Open No. 53-28246 stores the maximum value of the terminal voltage of a storage battery and controls charging when the terminal voltage drops by a certain voltage or more from the maximum value. According to the description in this publication, a fully charged state of a sealed nickel-cadmium storage battery can be obtained by controlling charging when the terminal voltage has decreased by a certain value from the maximum value at the end of charging.

However, the above-mentioned charging device has a drawback that the maximum value decreases over time due to leakage current in the capacitor for storing the maximum value of the terminal pressure of the storage battery, making it impossible to control charging. In addition, if a storage battery is overcharged, overdischarged, or left unused for a long period of time, the terminal voltage peak value that occurs at the beginning of charging as shown in Figure 4 and at the end of charging may occur, or as shown in Figure 5. 1′! Even at the end of the L stage, the terminal voltage may hardly drop, which has the disadvantage of causing undercharging or overcharging.

Purpose of the Invention The present invention solves the above-mentioned drawbacks by reliably maintaining a voltage corresponding to the maximum terminal voltage that occurs at the end of charging of a storage battery, and at the same time preventing overcharging, overdischarging, and storage batteries that have been left unused for a long time to coexist. To provide a charging device capable of properly performing rapid charging even when the battery is in use.

Structure of the Invention The charging device of the present invention maintains a voltage lower by a fixed value than the terminal voltage of a storage battery charged via a constant voltage/constant current circuit and a switch circuit after a certain period of time has elapsed after charging has started. When the terminal voltage of the storage battery reaches the maximum value at the end of charging, the held voltage value is maintained, and charging is started when the terminal voltage matches the maintained voltage value or when a predetermined period of time has elapsed since charging was started. It is something that makes it stop.

EXAMPLES The present invention will be explained below using examples. #! Figure 1 is a block diagram of the charging device of the present invention, in which AC power is received at input terminal 1,
It is rectified and converted into a predetermined DC voltage by a constant voltage/constant current circuit 2, and charges a storage battery connected to an output terminal 11 via a switch circuit 4 that intermittents charging. Further, the AC power is input to the auxiliary power supply circuit B, which supplies control power to the constant voltage and constant current circuit 2, the reset circuit 6, the initial lock timer 8, the overcharge protection timer 10, and the like.

At the same time as charging of the storage battery is started, the initial reset timer 8 begins to operate, and when a preset period of time has elapsed, a signal e is sent to the reset circuit 6, and the reset circuit 6 is reset. is sent. Here, the fixed time set by the initial lock timer 8 is about 5 minutes, so that charging will not be stopped even if the charging characteristics shown in FIG. 4 are exhibited. The signal sent out causes the voltage holding circuit 7 to hold the terminal voltage of the storage battery at a voltage a' which is lower by a certain value than the terminal voltage obtained through the voltage dividing circuit 5, and outputs the terminal voltage to the comparator circuit 9 as the voltage C. This is a command to be input. This voltage holding circuit 7 increases as the charging of the storage battery progresses and its terminal voltage a rises, and when the terminal voltage a reaches its maximum value, it maintains the value corresponding to that value. . The terminal voltage a of the storage battery is compared with the voltage C in the comparison circuit 9, and when Sa>O, the output d is not sent out, and when -a≦C at the end of charging, the output d is sent out and applied to the switch circuit 4. This will turn off the battery and stop charging.

Furthermore, in order to prevent overcharging even if the storage battery exhibits charging characteristics as shown in FIG. 4 is turned off to stop charging.

The charging device configured as described above will be explained with reference to the main circuit diagram of FIG. 2. In FIG. 2, parts having the same functions as in FIG. 1 are designated by the same reference numerals. When charging of the storage battery is started and a certain period of time has elapsed, an L level signal θ is sent from the initial lock timer 8 to the reset circuit 6, and this signal e
As a result, the pace current flowing to the transistor 61 via the resistor 62 disappears, the short circuit of the capacitor 75 in the voltage holding circuit 7 is released, and the terminal voltage a of the storage battery applied to the voltage holding circuit 7 is lowered by a certain value. voltage a'
As a result, charging of the capacitor 75 is started via the operational amplifier 71, the diode 72, and the resistor 73. At this time, the voltage between the left and emitter of transistor 1 is set to capacitor 6.
5 gradually increases the output voltage of the operational amplifier 71 (control 1!) whose capacitor 75 is higher than the voltage a'.
The terminal voltage a of the storage battery is charged by the power supply voltage) and sent to the comparator circuit 9.
A higher voltage is applied to keep charging from stopping. In this way, as charging of the storage battery progresses and the terminal voltage rises, the voltage of the capacitor 75 also increases.
The voltage increases to match the voltage a' applied to the voltage a'. When the terminal voltage of the storage battery decreases at the end of charging, the voltage a' also decreases, and the output of the operational amplifier 71 becomes L level. However, the diode 72 is reverse biased by the voltage of the capacitor 75, and the capacitor 75 is at the highest terminal voltage. The operational amplifier 9 in the comparator circuit 9 maintains the voltage value corresponding to the value.
1 non-inverting input terminal. Charging is then stopped when the voltage matches the terminal voltage applied to the inverting input terminal. However, the leakage current of the diode 72 and the capacitor 75
Because the voltage of the capacitor 75 gradually decreases due to its own self-discharge, charging may not stop. Therefore, in the device of the present invention, one end of the capacitor 75 that is not grounded is connected to the control iai via the diode 65 and the resistor 64, and the diode 63 is connected to the control power supply voltage and the capacitor 7.
The diode 63 is reverse biased by the voltage difference between the diode 63 and the voltage of the capacitor 5, and the leakage current of the diode 63 flows into the capacitor 75, thereby suppressing the voltage drop of the capacitor 75. It should be noted that the operational amplifier 74 in the voltage holding circuit 7 is used as a voltage regulator 7, and its output C has the same value as the voltage of the capacitor 75.

Next, the above operation will be explained with reference to the charging characteristic diagram shown in FIG.

In FIG. 3, the fixed time set by the initial thick timer 8 is tl, and when this time t1 elapses, a voltage a' lower by a fixed value ΔV than the terminal voltage of the storage battery is held in the voltage holding circuit 7, and the comparator circuit 9 as a voltage C. At time t2, when the terminal voltage a of the storage battery reaches its maximum value, the voltage a' maintains the voltage at that time, but
As described above, since the one end of the capacitor 75 that is not grounded is connected to the control power source via the diode 63 and the resistor 64, the held voltage does not drop as shown in ← in FIG. 3. Then, at time t3, voltage a and voltage a'
If they match, charging will be stopped, but charging is also stopped when the predetermined time t4 set by the overcharge protection timer 10 has elapsed.
Even batteries exhibiting such charging characteristics will not be overcharged.

Effects of the Invention As detailed in the embodiments, the charging device of the present invention is configured such that the leakage current of the diode flows into the capacitor that holds the voltage corresponding to the maximum value of the terminal voltage that occurs at the end of charging of the storage battery. By ensuring that the voltage is maintained, and by providing an initial lock timer and overcharge protection timers, it is possible to properly perform rapid charging even when overcharged, overdischarged, or long-term storage batteries are mixed together. It is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a charging device of the present invention, FIG. 2 is a circuit diagram of a main part of the charging device of the present invention, and FIGS. 3, 4, and 5 are charging characteristic diagrams.

Claims (2)

[Claims] (1) After a certain period of time has elapsed after charging has started, the output of a reset circuit that is reset by applying a signal sent from the initial lock timer starts holding a voltage that is a certain value lower than the terminal voltage of the storage battery, A voltage holding circuit maintains the voltage held when the terminal voltage of the storage battery reaches its maximum value at the end of charging, and compares this maintained voltage value with the terminal voltage of the storage battery, and outputs when the two match. and an overcharge protection timer that outputs an output after a predetermined time elapses after charging has started, and the battery is configured to stop charging due to the output of the comparison circuit or the output of the overcharge protection timer. Characteristic charging device. (2) A resistor and a diode are connected in series between one end of a capacitor, which maintains a voltage lower than the terminal voltage of the storage battery by a certain value, and the control power supply, and the diode is connected to the voltage difference between the voltage of the capacitor and the control power supply voltage. The charging device according to claim 1, wherein the charging device is reverse biased.