JPH0546262A - Alternating current fixed voltage device - Google Patents

Abstract

PURPOSE:To make low-priced, small and light-weight by detecting respectively the voltage of an alternating current power and the voltage of a switching element through a resistor and detecting as the load voltage with the difference voltage. CONSTITUTION:A first voltage detecting part 14 detects the voltage of an alternating current power 11 through a resistor 19. A second voltage detecting part 15 detects the voltage of a switching element 12 through a resistor 18. In this case, the voltage of a load 13 is the value to subtract the voltage of the switching element 12 from the voltage of the alternating current power 11. That is, by obtaining the difference voltage between the output of the first voltage detecting part 14 and the output of the second voltage detecting part 15, the load voltage can be detected. The difference voltage is obtained by a subtracting part 16. In accordance with the size of the output of the subtracting part 16, a control part 17 controls the conduction of the switching element and the load voltage is made constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC constant voltage device which constantly controls an AC load voltage of a lamp, a heater or the like.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional AC constant voltage device. In the figure, 11 is an AC power source, 12 is a switching element, 13 is a load such as a lamp or a heater, and these have a series circuit configuration. Reference numeral 21 is a voltage detection unit, 22 is a transformer, and 17 is a control unit.

Next, the operation will be described. Voltage detector 2
1 detects the AC voltage of the load 13 through the insulating traton 22. The voltage detector 21 outputs a DC voltage corresponding to the detected AC voltage to the controller 17. The control unit 17 controls the conduction of the switching element 12 in order to make the AC voltage of the load 13 constant according to the voltage from the voltage detection unit 21.

[0004]

Since the conventional AC constant voltage device is constructed as described above, there is a problem that the transformer 22 is required, which is expensive, large in size and heavy in weight.

The present invention has been made to solve the above problems, and an object thereof is to obtain an AC constant voltage device which is inexpensive, small in size, and lightweight.

[0006]

An AC voltage regulator according to the present invention comprises a first voltage detector for detecting a voltage of the AC power source in a series circuit of an AC power source, a load and a switching element, and the switching element. A second voltage detection unit that detects the voltage of the first voltage detection unit, a subtraction unit that outputs a difference voltage between the output of the first voltage detection unit and the output of the second voltage detection unit, and And a control unit for controlling conduction of the switching element.

[0007]

In the present invention, the subtracting section obtains and outputs the difference voltage between the output from the first voltage detecting section and the output from the second voltage detecting section. The difference voltage is used as the detection voltage of the load voltage, and the control unit controls the switching element.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is an AC power supply, 12 is a switching element, 13 is an AC load such as a lamp or a heater, 14 is a first voltage detection unit, 15 is a second voltage detection unit, and 16 is a first voltage detection unit. 14 is a second voltage detection unit, 16 is a subtraction unit for obtaining a voltage difference between the output of the first voltage detection unit 14 and the output of the second voltage detection unit 16, and 17 is a subtraction unit from the subtraction unit 16. A control unit for controlling conduction of the switching element 12 according to the output, 18 is a resistor for the second voltage detection unit 15 to detect the voltage of the switching element 12, and 19 is a first voltage detection unit 14 for the AC power supply. 11 is a resistor for detecting the voltage of 11.

Next, the operation will be described. The first voltage detection unit 14 detects the voltage of the AC power supply 11 via the resistor 19. The second voltage detector 15 detects the voltage of the switching element 12 via the resistor 18. The voltage of the load 13 is a value obtained by subtracting the voltage of the switching element 12 from the voltage of the AC power supply 11. That is, the first voltage detector 1
The load voltage can be detected by obtaining the differential voltage between the output of No. 4 and the output of the second voltage detection unit 15. The subtraction unit 16 obtains the difference voltage. The control unit 17 controls conduction of the switching element according to the magnitude of the output of the subtraction unit 16 so that the load voltage becomes constant.

Since the voltage detected through the resistors 18 and 19 is AC, it is necessary to convert this to DC. Therefore, an absolute value circuit or a rectifier circuit for converting an AC waveform into a DC is required.
The voltage detection unit 14 and the second voltage detection unit 15 may be provided at a front stage inside the subtraction unit 16 or may be provided at a rear stage inside the subtraction unit 16, but there is no particular limitation.

[0011]

As described above, according to the present invention, the voltage of the AC power source and the voltage of the switching element are respectively detected through the resistors, and the difference voltage between them is detected as the load voltage. There is an effect that the device is inexpensive, small, and lightweight.

[Brief description of drawings]

FIG. 1 is an AC voltage regulator according to an embodiment of the present invention.

FIG. 2 is a conventional AC constant voltage device.

[Explanation of symbols]

 11 AC Power Supply 12 Switching Element 13 Load 14 First Voltage Detection Section 15 Second Voltage Detection Section 16 Subtraction Section 17 Control Section 18 Resistor 19 Resistor

Claims (1)

[Claims] 1. A first voltage detection unit for detecting a voltage of the AC power supply in a series circuit of an AC power supply, a load, and a switching element, a second voltage detection unit for detecting a voltage of the switching element, and a first voltage detection unit. A subtraction unit that outputs a voltage difference between the output of the first voltage detection unit and the output of the second voltage detection unit; and a control unit that controls conduction of the switching element according to the output of the subtraction unit. AC constant voltage device characterized by.