JP2709217B2 - AC voltage regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC voltage regulator for controlling 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 supply, 12 is a switching element, 13 is a load such as a lamp and a heater, and they are in a series circuit configuration. 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 via the insulating tratons 22. The voltage detector 21 outputs a DC voltage corresponding to the detected AC voltage to the controller 17. The control unit 17 controls conduction of the switching element 12 to keep 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 configured as described above, the transformer 22 is required, and there is a problem that it is expensive, large in size, and heavy.

The present invention has been made to solve the above problems, and has as its object to provide an inexpensive, compact, and lightweight AC constant voltage device.

[0006]

An AC constant voltage apparatus according to the present invention comprises a first voltage detecting section 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 the voltage of the first voltage detection unit, a subtraction unit for outputting a difference voltage between the output of the first voltage detection unit and the output of the second voltage detection unit, And a control unit for controlling conduction of the switching element.

[0007]

In the present invention, the subtraction section calculates and outputs the difference voltage between the output from the first voltage detection section and the output from the second voltage detection 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 One 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 detector, 15 is a second voltage detector, and 16 is a first voltage detector. 14 is a subtraction unit for obtaining a difference voltage between the output of the first voltage detection unit 14 and the output of the second voltage detection unit 16; A control unit for controlling conduction of the switching element 12 according to the output; 18, a resistor for the second voltage detection unit 15 to detect the voltage of the switching element 12; 19, a first voltage detection unit 14 for the AC power supply 11 is a resistor for detecting voltage.

Next, the operation will be described. The first voltage detector 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 calculating the difference voltage between the output of the second voltage detector 4 and the output of the second voltage detector 15. The difference voltage is obtained by the subtractor 16. The control unit 17 controls the 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 an alternating current, it is necessary to convert this to a direct current. For this reason, an absolute value circuit or a rectifier circuit for converting an AC waveform into a DC is required.
May be provided in the preceding stage inside the voltage detecting unit 14 and the second voltage detecting unit 15, or may be provided in the subsequent stage inside the subtracting unit 16, but there is no particular restriction.

[0011]

As described above, according to the present invention, the voltage of the AC power supply and the voltage of the switching element are respectively detected via the resistors, and the difference voltage is detected as the load voltage. There is an effect that an inexpensive, compact and lightweight device can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a conventional AC constant voltage device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 AC power supply 12 Switching element 13 Load 14 First voltage detection unit 15 Second voltage detection unit 16 Subtraction unit 17 Control unit 18 Resistor 19 Resistor

Claims (1)

(57) [Claims] A first voltage detector 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 detector for detecting a voltage of the switching element; 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 a control unit that controls conduction of the switching element according to the output of the subtraction unit. An AC constant voltage device.