JPH01107651A - Power control circuit - Google Patents

Abstract

PURPOSE:To prevent higher harmonics and noise by turning ON and OFF a load at the zero-crossing point of a power frequency and by adjusting the number of half-wave or full-wave cycles to be turned ON according to a power controlled variable. CONSTITUTION:A power control circuit is equipped with a set point register 1, a sine wave number counter 2, a comparison operation circuit 3, a zero- crossing inspection output circuit 4, and a load closing signal generation circuit 5 to control supplying a load (lighting device) 7 with AC power according to a signal generated in a load closing signal generation circuit 6. Further, a pulse by the number proportional to the value of the set point register 1 appears as the output in the comparison operation circuit 3 and, as the output of said generation circuit 5, a pulse for connecting the AC power with a load for 180 degrees appears together with the zero-crossing pulse of the AC power at the first zero-crossing point after an output has appeared in the comparison operation circuit 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power control circuit used in a dimmer of lighting equipment or an electric heating device used with an AC power supply, and relates to a power control circuit used in a power supply frequency zero-crossing point. The present invention relates to a power control circuit that has been improved so as to perform power adjustment by turning on and off a load and adjusting the number of half-wave or full-wave cycles of load turning on according to a power control amount.

[Conventional technology]

Conventionally, this type of power adjustment circuit has a negative -
The power was adjusted by shifting the phase point at which the power was applied from the zero-crossing point.

[Problem that the invention seeks to solve]

The above-mentioned conventional power control circuit adjusts the power based on the amount of deviation of the load application point from the zero-crossing point, so it has the disadvantage that it generates a large amount of harmonics when the load is applied, which becomes a noise source.

[Means for solving problems]

The power control circuit of the present invention uses a comparison calculation circuit to check a counter that counts the number of sine waves in an AC power source and a value of a digitizer that sets the required degree of dimming as a numerical value, and sets it to a predetermined setting value. A circuit that outputs a proportional number of pulses as the result of the comparison operation, and detects this output and the zero-crossing point of the AC power supply, turns on the load at the zero-crossing point of the AC power supply, and calculates the power output as the result of the comparison operation. It has a function to apply load for the number of half-wave or full-wave cycles depending on the control amount.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. The set value digitizer 1 is a cell that stores a set value for dimming as a numerical value. The sine wave number counter 2 is a circuit that continuously counts the number of sine waves in the AC power source. The comparison calculation circuit 3 is a circuit that compares the values of the set value register 1 and the sine wave number counter 2, and allows only the number of pulses proportional to the value of the set value register to pass within a unit time. The zero-crossing point detection circuit 4 generates a pulse when the phase of the sine wave of the AC power source crosses zero; the load-on signal generating circuit 5 temporarily holds the pulse output from the comparison calculation circuit 3; This circuit generates a pulse that applies a load for 180 degrees of the sine wave from the zero cross point of the sine wave detected by the zero cross point detection circuit 4. The load application control circuit 6 connects the AC power supply to the load application signal generation circuit 6.
This circuit actually opens and closes the circuit to the load (lighting device) according to the signals generated by the

FIG. 2 is a waveform diagram showing the operation of the embodiment shown in FIG. For an AC power source as shown in FIG. 2A, a number of pulses proportional to the value of the set value digitizer 1 appear in the output of the comparator circuit as shown in FIG. 2B. Further, as shown in FIG. 2C, the output of the zero-crossing point detection circuit 4 appears as a pulse when the AC power supply zero-crosses. As shown in the second diagram, the output of the load application signal generation circuit 5 is connected to the AC power supply at the first zero cross point after the output appears in the comparison calculation circuit 3.
A pulse appears as an output for connecting to a minute load. As shown in FIG. 2E, the output of the load application control circuit 6 closes the open circuit in which the output of the load application signal generation circuit 5 appears, and connects the AC power source to the load.

〔Effect of the invention〕

As explained above, the present invention turns the load on and off at the zero-crossing point of the power supply frequency,
In addition, by controlling the power by adjusting the number of half-wave or full-wave cycles that are turned on according to the amount of power control, power control can be performed without generating harmonics or noise due to steep circuit input. effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the operation of FIG. 1. 1...Set value digitizer, 2...Sine wave number counter, 3
. . . Comparison calculation circuit, 4 . . . Zero cross point detection circuit, 5 . . . Load application signal generation circuit, 6 . . . Load application control circuit.

Claims (1)

[Claims] A power control circuit characterized by turning on and turning off a load at a zero-crossing point of a power supply frequency, and adjusting the number of half-wave or full-wave cycles for turning on according to a power control amount. .