JPS6018177B2 - Storage battery charging device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a storage battery charging device.

In conventional devices that rapidly charge storage batteries such as nickel-cadmium batteries by high-current charging, the high-current charging is stopped by detecting the storage battery voltage.

However, storage batteries such as nickel-cadmium batteries are the first
It has a charging voltage characteristic A as shown in the figure, and a peak point P before the saturation point t of the charging amount characteristic B. Therefore, the maximum detection of the storage battery voltage is at the peak time t2, and in practice, since the charging voltage characteristic A near the peak point has a gentle slope, it is very difficult to detect the peak point voltage V, and at the peak point Since the storage battery voltage V2 is detected at time t3 in the range where the slope before t is steep, the charge amount q
was smaller than its saturation value Q. Further, due to variations in storage batteries, the charging voltage characteristics have variations as shown in A, A2 in FIG. 2, and if the detection voltage V2 is uniquely determined, the amount of charge may be very small depending on the storage battery. The present invention was invented in view of the above points, and focuses on the point that the charging voltage characteristics of a storage battery gradually decreases after the peak point, stores the peak point voltage or its corresponding voltage, and stores the peak point voltage or its corresponding voltage, and stores the peak point voltage or its corresponding voltage. The system attempts to stop high-current charging by comparing and detecting a predetermined decrease in voltage difference of 0 voltage between the decreasing storage battery voltage or its corresponding voltage.

An embodiment of the present invention will be described below with reference to FIG.

1' is a step-down transformer, and its primary coil 2 is connected to AC power supply terminals 3, 3, and its secondary coil 4' is connected to a series circuit of a rectifier diode 5 and a smoothing capacitor 6.

Both ends of this capacitor 6 form positive and negative charging lines 8 and 9 via a switch transistor 7. A base resistor 10 is connected between the base and collector of the switch transistor 1, and a collector and emitter of a control transistor 11 are interposed between the base and the negative charging line 9. A storage battery 12 is connected between the positive and negative charging lines 8 and 9, and a voltage detection circuit 13 is provided at both ends of the storage battery to detect a voltage corresponding to the storage battery voltage, and a voltage detection circuit 13 corresponding to the peak point voltage V of the charging voltage characteristic A. A memory circuit 14 for storing the voltage applied thereto is provided in parallel.

The voltage detection circuit 13 is composed of a constant voltage element 15 and a resistor 16 connected in series. The memory circuit 14 is a constant voltage element 17
The main circuit is composed of a series circuit of a reverse current blocking diode 18 and a capacitor 19, and the collector and emitter of a short-circuit transistor 20 are connected to both ends of the capacitor 19. A starting switch 21 is inserted. Next, 22 is a comparison circuit connected between the charging lines 8 and 9, and is configured with an operational amplifier 23 as its main elements.
The voltage at the connection point 24 and the diode 18 of the memory circuit 14
The output terminal of the amplifier 23 is connected to the base of the control transistor 11, and the output terminal of the amplifier 23 is connected to the voltage at the connection point 25 between the capacitor 19 and the connection point 24.
is inserted.

In the above configuration, when AC power is applied to the primary coil 2 and the starting switch 21 is temporarily opened, the short-circuit transistor 20 becomes conductive at the storage battery voltage, so the capacitor 19
The storage voltage of becomes zero.

Therefore, there is no output from the operational amplifier 23, the control transistor 11 is cut off, and the switch transistor 7 is turned on to charge the storage battery 12. As the charging time elapses, the storage battery 12 is charged according to the charging voltage characteristic A. Corresponding to this characteristic, the detected voltage at the connection point 24 is
In the figure, the characteristic is A, and the storage voltage at the connection point 25 is the characteristic A2.
becomes. In this case, up to the peak time point t2, the connection point 2
The difference voltage between the detection voltage of 4 and the storage voltage of connection point 25 is constant △
V, and there is no output from the operational amplifier 23. After the peak point, the storage voltage at the connection point 25, ie, the capacitor voltage, is maintained at a constant value by the presence of the backflow blocking diode 18. On the other hand, as is clear from the characteristic A, the detected voltage at the connection point 24 decreases in response to a decrease in the storage battery voltage. When this detection voltage becomes equal to the storage voltage, the operational amplifier 23 performs comparison detection and outputs an output, thereby turning on the control transistor 11. Therefore, the switch transistor 7 is cut off due to a drop in its base voltage, and charging of the storage battery is stopped. The detected voltage at the connection point 24 corresponding to the storage battery voltage is determined by the constant voltage value of the constant voltage element 15, and the difference voltage E between characteristics A and A is equal to the constant voltage value of the constant voltage element 15. Become.

Furthermore, the memory voltage corresponding to the peak voltage V of the storage battery is determined by the constant voltage value of the constant voltage element 17 and the forward rising voltage value of the diode 18, and the voltage difference between characteristics A and A2 is
is the sum of the constant voltage value of the constant voltage element 17 and the forward rising voltage value of the diode 18. Therefore, the predetermined drop in differential voltage ΔV after the peak point in characteristic A is equal to the difference between voltages V and V2. Therefore, for example, if the constant voltage value of the constant voltage element 15 is selected so that the detected voltage characteristic of the connection point 24 becomes A', the predetermined voltage drop difference voltage of the detected voltage with respect to the storage voltage becomes ΔV'. In this way, by selecting the detection corresponding voltage corresponding to the storage battery voltage and the storage corresponding voltage corresponding to the peak point voltage of the storage battery, it is possible to adjust the predetermined decreased differential voltage AV. Note that it is desirable to set the predetermined decreased differential voltage ΔV so that its detection time coincides with the saturation time t of the charge amount characteristic B.

Furthermore, the starting switch 21 may be connected across the capacitor 19 without using the shorting transistor 20. 2
As mentioned above, the present invention utilizes the point that the charging voltage characteristic of a storage battery increases with the passage of charging time and gradually decreases after the peak point,
The corresponding voltage corresponding to the peak point voltage is memorized, and the charging current of the storage battery is cut off by comparing and detecting a predetermined voltage drop difference between the stored voltage and the corresponding voltage of the storage battery voltage, so that charging occurs after the peak point of the characteristics. Since the battery can be stopped, the amount of charge in the storage battery can be brought close to its saturation value (100%). Furthermore, even when the characteristics vary depending on the storage battery, the storage battery can be charged according to the peak point of the characteristics of each storage battery, and the variation in the amount of electricity charged by the storage battery can be reduced compared to conventional counterfeiting. Furthermore, by selecting a storage voltage corresponding to the peak point voltage and a detection voltage corresponding to the storage battery voltage,
The predetermined voltage drop difference can be determined almost arbitrarily, and the storage battery can be charged to a desired state.

[Brief explanation of drawings]

FIG. 1 is a charging characteristic diagram of a storage battery, FIG. 2 is a characteristic diagram showing variations in charging voltage characteristics, and FIG. 3 is an electric circuit diagram showing an embodiment of a charging device according to the present invention. 12...Storage battery, A...Charging voltage characteristics, V
．． ... Peak point voltage, 13 ... Detection circuit, 14 ... Memory circuit, 22 ... Comparison circuit, △V ... Predetermined decrease Differential voltage, 21...
...Start switch. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A storage circuit that stores a corresponding voltage corresponding to a peak point voltage of a charging voltage characteristic of a storage battery, a detection circuit that detects a corresponding voltage that corresponds to a storage battery voltage after the peak point of the characteristic; A comparator circuit that controls charging of the storage battery by detecting when the detection voltage of the detection circuit drops by a predetermined difference from its peak value with respect to the storage voltage of the storage circuit, and the difference between the two voltages becomes substantially zero. A charging device for a storage battery, comprising: determining the predetermined reduced voltage difference by selecting the storage compatible voltage and the detection compatible voltage. 2. The storage battery charging device according to claim 1, wherein the storage circuit includes a start switch that sets the storage voltage to zero at the start of charging the storage battery.