JPS5943895B2 - battery charging circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit that operates a transistor inverter using a rectified voltage of a commercial power source and charges a battery with a half-wave current obtained by rectifying the inverter output.

With this type of circuit, the battery can be charged quickly by increasing the inverter output.

In order to prevent overcharging of the battery during rapid charging, the battery voltage is detected and the rapid charging is stopped when a predetermined voltage is reached. However, in this type of conventional device, the battery voltage is detected when the charging current flows, so the voltage drop is included in the detection due to the internal impedance of the battery, resulting in false detection of the battery voltage. .

In particular, the half-wave current obtained by rectifying the inverter output becomes a pulse current, and its peak value is larger than the average photoelectric current value. Therefore, when detecting the battery voltage when a pulse charging current flows, the battery voltage appears to be large, and immediately This has the disadvantage that charging is stopped and the battery cannot be sufficiently charged. The present invention was invented in view of this point, and one embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a full-wave rectifier circuit whose AC input end is connected to a commercial power source 2, and whose DC output end is connected to a series circuit of a reverse current blocking diode 3 and a smoothing capacitor 4. 5 is a transistor inverter, and a series circuit of the primary coil T of the oscillation transformer 6 and the collector-emitter of the oscillation transistor 8 is connected to both ends of the smoothing capacitor 4. A series circuit including a feedback coil 9, a resistor 10 for determining the oscillation frequency of the inverter 5, and a capacitor 11 is connected.

A series circuit of a resistor 12 and a capacitor 13 for absorbing spike voltage is connected to both ends of the primary coil 7. In addition, the secondary coil 14 of the oscillation transformer 6 is connected to the rectifier diode 1.
5 to the battery to be charged 16 . Next, 17 is a reference voltage circuit, and a series circuit of a resistor 18 and a Zener diode 19 is connected to the DC output terminal of the full-wave rectifier circuit 1 to obtain a constant voltage across the Zener diode 19, which is divided by resistors 20 and 21. It's pressing.

This voltage division point 22 becomes the anode voltage of a programmer's uniform union transistor (hereinafter referred to as PUT) 23. Further, the gate of PUT 23 is connected to the anode of battery 16 via resistor 24, and the cathode of PUT 23 is connected to the base of oscillation transistor 8 via resistor 25 to form a base bias circuit. In the above configuration, the voltage at the voltage dividing point 22 of the reference voltage circuit 17 has a waveform 2, which is a reference constant voltage V, as compared to the voltage waveform V1 when the Zener diode 19 is not connected, as shown in FIG.

has. On the other hand, the battery voltage at the start of charging is the reference constant voltage of waveform 2 in each half cycle. lower. Therefore, when the voltage dividing point voltage V2 is higher than the battery voltage, that is, when the anode voltage of the PUT 23 is higher than the gate voltage, the PUT 23 becomes conductive, the base current flows through the oscillation transistor 8, and the inverter 5 oscillates. Further, once the PUT 23 is conductive, it continues to conduct until the current drops to the holding current, but at the end of each half cycle, the holding current becomes less than the holding current, so the PUT 23 is cut off, and the inverter 5 oscillates every half cycle. In this way, the inverter 5 oscillates every half cycle, and the oscillation output is rectified by the rectifying diode 15, and the battery 16 is charged by the pulsed half-wave current.

In FIG. 2, 3 indicates the battery voltage waveform, and the pulse-like waveform portion 31 indicates charging by the oscillation output of the inverter 5,
The lower envelope curve V32 rises with time, indicating that the battery voltage increases. Further, the connection line section 33 between the charging end point P1 of the first half cycle and the charging start point P2 of the second half cycle is connected to the connecting line section 33 after a chemical reaction occurs rapidly within the battery due to the pulsed half-wave current. This indicates that the battery voltage is reduced as the battery enters a stable state, and as charging progresses, this connection line portion V33 gradually rises. In the figure, a shows a state when the battery voltage is low, and b shows a state when the battery voltage is high. However, when the battery voltage is low and charging is not progressing sufficiently,
Connecting line portion 3 of battery voltage waveform V3 as shown in FIG. 2a.
3 is still low because it hasn't risen enough.

Therefore, the connection line portion 33 of the battery voltage waveform 3 becomes lower than the voltage division point voltage V2 of the reference voltage circuit 17 after the point P3. As a result, the gate voltage of the PUT 23 becomes lower than the anode voltage, the PUT 23 becomes conductive, and the oscillation transistor 8
A current flows through the base of the oscillation transistor 8, and the oscillation transistor 8 becomes conductive and starts oscillating. However, the output voltage of the inverter 5 due to the oscillation of the oscillation transistor 8 is still lower than the battery voltage immediately after the oscillation of the oscillation transistor 8, and no current flows from the secondary coil 14 to the battery, and no current flows to the battery 16. Since the voltage is not supplied, the battery 16 cannot be charged immediately after the oscillation transistor 8 oscillates. Eventually, the chemical reaction inside the battery 16 charged in the first half cycle becomes stable, and the connection line portion V33 further decreases. Furthermore, the output voltage of the inverter 5 also increases. A charging current is then supplied to the battery 16 as shown by the pulse-like waveform portion 31 in the figure. Here is the charging starting point P
2 is the intersection of the upper envelope 34 of the pulse waveform section 31 and the connection line section 33, and when charging is not progressing sufficiently and the battery voltage is low, the PUT 23 becomes conductive at the point P3. However, the battery 16 is actually charged at the point P2.
It will be later. When the battery voltage increases in this manner, the connecting line portion 33 is at the reference constant voltage as shown in FIG. 2b. When the point P4 is reached as below, the inverter 5 operates to oscillate. Therefore, the period T1 of the pulse waveform portion V3 of each half cycle is shorter than the period T2 when the battery voltage is low. Therefore, the average charging current of the battery 16 gradually decreases after the predetermined charging time t, as shown at 1 in FIG. On the other hand, as shown in the figure, the average charging voltage of the battery 16 continues to rise until time t, and then becomes a constant voltage. As described above, according to the present invention, a PUT is provided for comparing the battery voltage during non-charging with a reference constant voltage between the gate and anode, and this PUT is inserted into the base bias circuit of the oscillation transistor of the inverter. Therefore, the battery voltage detection error can be reduced compared to the case where the battery voltage is detected when the charging current is flowing. Furthermore, in order to detect the battery voltage when not being charged, a pulse current with a high peak value can be used as the charging current, and the battery can be charged to a desired voltage using a transistor inverter.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a charging circuit diagram according to the present invention, FIGS. 2A and b are battery voltage waveform diagrams when the battery voltage is low and high, and FIG. 3 is a battery charging diagram. It is a characteristic diagram. 5...Inverter, 16...Battery, 2
3...PUT, 8...Oscillation transistor.

Claims (1)

[Claims] 1. In a device that operates a transistor inverter with the rectified voltage of a commercial power supply and charges a battery with a half-wave current obtained by rectifying the inverter output, a reference voltage circuit that operates with the rectified voltage is provided, and the reference voltage circuit is The cathode side of the programmable unijunction transistor whose anode side is connected is connected to the base bias circuit of the oscillation transistor of the inverter, the battery is connected to the gate side of the programmable unijunction transistor, and the reference voltage and the battery voltage,
By comparing and detecting conduction and non-conduction of the programmable unijunction transistor, the battery voltage when no charging current flows is detected, and the battery voltage is detected by the operation of the programmable unijunction transistor. A battery charging circuit configured to control the output of the inverter.