JPH03219314A - Power supply circuit - 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 Industrial Application] The present invention relates to a power supply circuit used in electronic application equipment.

[Conventional technology]

FIG. 5 is a diagram showing a conventional power supply circuit disclosed in, for example, Japanese Unexamined Patent Publication No. 60-128869, and in the figure (1)
, (2) is the voltage input section, (3) is the rectifier diode, (
4) is a Zener diode for generating reference voltage, (51 is a thyristor for voltage comparison, (6) is a transistor for current switch, ('71 is a smoothing capacitor, (8), (9)
) is the output terminal.

The conventional power supply circuit is configured as described above, and its operation is as shown in FIG.
), and while this input voltage V(t) is lower than the reference voltage VZ of the Zener diode (4), the thyristor (5) is in a non-conducting state, the transistor (6) is in a conducting state, and the smoothing capacitor (7) is in a non-conducting state. ) Charging current flows through. On the other hand, when the input voltage V (t) becomes higher than the reference voltage Vz, the thyristoro becomes conductive, and the smoothing capacitor (71
The charging current to is cut off. As a result, the section A in FIG. 6 is the section where the charging current is supplied.

[Problem to be solved by the invention]

In the conventional power supply circuit as described above, since the thyristor (5) is used as the voltage comparator, the smoothing capacitor (7) is charged only once during one input cycle, as shown in Figure 6. First, the power supply circuit cannot output a large current, and the thyristor (51) generates noise peculiar to the circuit, resulting in malfunction.

This invention was made to solve the problem,
It is an object of the present invention to provide a power supply circuit that can generate a large amount of output current during one cycle, can output a large current, and does not malfunction due to noise from a thyristor.

[Means to solve the problem]

A power supply circuit according to the present invention is a power supply circuit that receives an AC voltage as an input and outputs a DC voltage. a voltage comparison section that compares the reference voltage output from the voltage comparison section with the rectified output from the rectification section; a switch section that turns on and off the rectified output according to the output of the voltage comparison section; and a smoothing section that smoothes the output of the switch section. It is equipped with the following.

[Effect]

In this invention, in a power supply circuit that receives an AC voltage as an input and outputs a DC voltage, a rectifier that adjusts the direction of current, a reference voltage generator that generates a reference voltage from the rectifier,
a voltage comparison section that compares the reference voltage output from the reference voltage generation section and the rectification output from the rectification section; and a switch section that turns on and off the rectification output based on the output of the voltage comparison section;
Since the smoothing section is provided to smooth the output of the switch section, the input voltage is compared with the reference voltage in the voltage comparison section, and the switch section is turned on and off by the output of the voltage comparison section.

〔Example〕

FIGS. 1 to 3 are diagrams showing an embodiment of the present invention,
In the figure, 00) is a power supply circuit (11) that is a rectifier of this power supply circuit, and one rectifier diode (12) is used.
Adjusts the direction of the input AC voltage current. (13) is a reference voltage generating section which generates a reference voltage from this rectifying section, and is composed of a constant voltage diode (14). (15) and (16) are AC voltage input terminals of the power supply circuit α0), and (17) is a voltage comparator, which compares the reference voltage output from the reference voltage generator (13) with the rectifier (11). A comparison is made with the rectified output, and the output is input to a switch section to be described later. (1
Reference numeral 8) denotes a switch section which makes the rectified output conductive using the output from the voltage comparison section (17), and becomes conductive when the input voltage is lower than the reference voltage. <19) is a smoothing section, which is composed of a smoothing capacitor (20) and smoothes the output of the switch section (18). (21) and (22) are output terminals of the power supply circuit ω, from which the converted DC voltage is output.

In the power supply circuit configured as described above, when the input voltage V(t), which is a DC voltage, is input to the AC voltage input terminals (15) and (16) as shown in FIG. When the input voltage V (t) is higher than the reference voltage Vz determined in the section (13), the voltage comparison section (17)
N, the switch section (I8) is turned OFF. Conversely, when the input voltage V (t) is lower than the reference voltage Vz, the voltage comparison section (17) is turned OFF and the switch section (18) is turned ON.
The smoothing capacitor (20) of the smoothing section (19) is charged until the terminal voltage becomes constant, and the output terminals (21) and (22)
DC voltage is output. In this case, the charging part is
This is part B in the figure, and the input voltage V (t) occurs twice in one cycle.

In the above embodiment, one rectifying diode (12) was used in the rectifying section (11), but if a bridge configuration using four rectifying diodes (12) is used as shown in FIG. 4, the input voltage V( The number of times that the smoothing capacitor (20) can be charged during the tH cycle is four times, and a large output current can be obtained, which improves the above embodiment.

In addition, as shown by C in Figure 4, the current can be increased by making the transistor that controls the current Darlington connected and the emitter grounded, or by adding a resistor (23) when C is conductive. Smoothing capacitor (2
0) can also be made smaller.

〔Effect of the invention〕

As explained above, this invention is based on a power supply circuit that receives AC voltage as input and outputs DC voltage. a voltage comparison section that compares the reference voltage output from the voltage comparison section with the rectification output from the rectification section, a switch section that values the rectified output based on the output of this voltage comparison section, and a smoothing section that smoothes the output of this switch section. The voltage comparison section compares the input voltage with the reference voltage and operates the switch section.In particular, by using a transistor in the voltage comparison section, the smoothing capacitor is charged many times during one cycle of the input voltage. Therefore, a large output current can be obtained, noise is eliminated, and malfunctions can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation, FIG. 3 is a system diagram, and FIG. 4 is a circuit diagram showing another embodiment of the invention. FIG. 5 is a circuit diagram showing a conventional power supply circuit, and FIG. 6 is a waveform diagram showing the operation of the conventional power supply circuit. In addition, QOI is a power supply circuit, (13) is a reference voltage generation part, (17) is a voltage comparison part, (18) is a switch part, and (19) is a smoothing part. Zukenkiri/?: Sui, /+1su5 /q'Mosaigo

Claims (1)

[Claims] In a power supply circuit that receives AC voltage as input and outputs DC voltage, there is a rectifier that adjusts the direction of current, a reference voltage generator that generates a reference voltage from this rectifier, and a reference voltage output from this reference voltage generator and the rectifier. A voltage comparison section that compares the rectified output from the voltage comparison section, a switch section that turns on and off the rectified output according to the output of the voltage comparison section, and a smoothing section that smoothes the output of the switch section. power supply circuit.