JPS6039218A - Load controller - Google Patents

Abstract

PURPOSE:To control a load by a desired power consumption without being affected by the fluctuation of a power supply voltage and the length of a line applying power to the load by comparing a control signal with a detection signal and controlling a conduction angle of a triac circuit so that the detection signal is coincident with the control signal. CONSTITUTION:The load 2 comprising lighting fixtures is energized by an AC power such as a commercial power supply 6 and the triac circuit 11 is inserted in series with the load 2. Further, a current transformer 14 is connected to detect a load current, its output is rectified 15 and given to an operational amplifier 19 of a multiplier 18 and a rated power of the load is set via a variable resistor 21. A fadar 1 introduces the control signal representing the rate of the rated power of the load 2 to the power consumption, the signal is amplified 25 in a comparator circuit 23 and given to a subtractor 24. An output of the multiplier 18 is given to the subtractor 24 and a difference of both inputs is led to a comparator 28 of a conduction angle control circuit 27. A sawtooth wave signal from a sawtooth wave generating circuit 29 is applied to other input of the comparator 28 so as to drive the load 2 by a prescribed power consumption via a trigger circuit 32 and the circuit 11.

Description

TECHNICAL FIELD The present invention relates to a device for controlling the conduction angle of a load such as a lighting fixture.

BACKGROUND ART A typical prior art is shown in FIG. fader 1
The ratio of power consumption to the rated power of the lighting fixture 2 is set by . The output from this fader 1 is, for example, 5
For example, it is set to -5V as shown in FIG. 2 fl) corresponding to 0%. The signal from the fader 1 is inverted by an inverting amplifier 3 with a gain of 1, and a voltage of 5V is derived from the line 4 as shown in FIG. 2(2). From the sawtooth wave generating circuit 5, a sawtooth wave synchronized with the voltage of the AC power source 6 is derived from a line 7 as shown in FIG. 2(3). The comparator circuit 8 outputs a signal that is at a high level only during the period when the signal level from the line 4 exceeds the signal level from the line 7 to the line 9 as shown in FIG. 2(4). Trigger circuit 10 is connected in series to lighting fixture 2 and power source 6. triac 11
The gate [fJZ gives the signal shown in diagram (5). In this way, the triac 11ij conducts at a rate of 50%, as shown in FIG. 2 (6), thereby performing square conduction control.

In such prior art, when the line length between the triac 11, the lighting equipment 2, and the power supply 6 is long, a voltage drop occurs, and this causes the power consumption ratio to the rated power of the lighting equipment 2 to be lower than 1-t50%. When the value becomes small, for example, about 45 to 48%, the voltage waveform applied to the lighting fixture 2 becomes low as shown in FIG. 2 (7).

To solve this problem, the prior art shown in FIG. 1 adjusts the gain of the 1-inverting amplifier 3. Such adjustment is troublesome because the inverting amplifier 3 must be adjusted individually due to differences in line lengths related to the lighting fixtures 2, differences in the rated power of the lighting fixtures 2, differences in the output voltage of the power supply 6, etc. It is. Moreover, although it is desirable to visually check the brightness of the lighting fixture 2 from the position where such an inverting amplifier 3 is installed, in reality, from the position where such an inverting amplifier 3 is installed, for example, from a dimming room. In many cases, it is not possible to see the stage on which the lighting equipment 2 is installed, and therefore it is extremely difficult to adjust the gain of the inverting amplifier 3.

Furthermore, when a plurality of lighting fixtures 2 are connected in parallel with mutually different line lengths and the energization angle is controlled by a common triac 11, due to the difference in line length,
A problem arises in that the brightness of the lighting fixture 2 varies.

Purpose An object of the present invention is to provide a load control device that can accurately control the ratio of power consumption to a rated 1 hour power of a load such as a lighting fixture to a predetermined value. .

Example FIG. 3 is an electrical circuit diagram of one embodiment of the present invention.

The lighting fixture 2#'i is energized by AC power from a commercial AC power source 6, etc. A triac 1 is connected in series to this load 2.
1 is mediated. Current transformer 14 to detect load current
is connected. The output from this current transformer 14 is the rectifier circuit 1
A resistor 20 is connected to one input of an operational amplifier 19 which is rectified by
given through. A variable resistor 21 for setting the rated power of the lighting fixture 2 is connected to the multiplier 18 .

The output from multiplier 18 is applied from line 22 to one input of a subtracter 24 included in comparator 23 .

The fader 1 derives a control signal representing the ratio of power consumption to the rated power of the load 2, and provides the control signal to an amplifier 25 included in a comparator 23. Gain i'i of amplifier 25
It is 2. The output from amplifier 25 is provided to subtracter 24. Subtractor 24 subtracts the output from multiplier 18 via line 22 from the output from amplifier 25 and provides the subtracted value from line 26 to one input of comparator 28 of conduction angle control circuit 27 . A sawtooth wave is applied to the other input of the comparator 28 via a line 30 from a sawtooth wave generation circuit 29 . Comparator 28 sends a high level signal to trigger circuit 32 via line 31 when the signal level on line 26 exceeds the sawtooth signal level on line 30.
give to

A signal from this trigger circuit 32 is applied to the gate of triac 11 via line 33.

Referring to FIG. 4, in order to set the power consumption ratio of the fader 1 to the rated power of the lighting fixture 2 to 50%, a voltage of 5V shown in FIG. 4 (1) is applied from the fader 1 to the comparator 23. derived. In fact, when the ratio of the power consumption to the rated power of the lighting fixture 2 is 49%, 4.0% is generated in the period from time t1 to time t2, which is the inverse period of the power supply voltage of the line 22, as shown in FIG. 4(2). A voltage of 9■ is derived. This causes the subtractor 24 to
Then, a voltage of 5.1V is derived as shown in FIG. 4(3).

From the sawtooth wave generation circuit 29 to the line 30, ij, m4 (
4), in each half cycle of the power supply voltage 1.
A sawtooth wave that decreases linearly from OV to Ov is provided. Therefore, the comparator 28 derives the signal shown in FIG. 4(5), and the trigger circuit 32 triac 1
All the signals shown in FIG. 4 (6) are derived to the gate No. 1.

As a result, the triac 11 conducts at a conduction angle of 51%, as shown in FIG. 4 (7), and the actual power consumption ratio of the lighting fixture 2 becomes 50%.

During the period from time 12 to t3, which is the next half cycle of the power supply voltage, the load current is detected by the current transformer 14, and the rectifier circuit 15 uses the full-wave rectified direct current (Af,'R voltage is the fourth
It has the waveform shown in Figure (8). The value corresponding to the load power from this line 16 is multiplied by a 1 multiplier 18 and the level is converted.

When the rated power of the lighting fixture 2 is 1 kW and dimming is performed at a rate of 50%, the load current is 5 A when the 2 power supply voltage is 100 V, and the voltage derived from the line 16 is 5 V. At this time, the variable resistor 21 is 1 multiplier 1
The gain of operational amplifier 19 at 8 is adjusted to be 1.

When the rated power of lighting fixture 2 is 2 and dimming is performed at a rate of 50%, the load current is IOA, and line 1
The voltage derived from 6 is 11tl OV. Therefore, the variable resistor 21 is adjusted so that the gain of the operational amplifier 19 is set to 1. The voltage Il″t of the signal thereby derived from line 22.

It becomes 5v corresponding to a ratio of 50%.

Thus, during the half cycle from time t2 to time t3, the voltage on the line 22 rises to 5V, and therefore the dimming level settles to 50%.

Waveforms are shown when the dimming level is changed in each of the other half cycles t3 to t4; t4 to t5.

The present invention can be implemented not only for dimming a lighting device, but also for controlling the conduction angle of other loads.

According to the embodiment described above, even if the rated power of the lighting equipment is different, it is easy to set the rated power using the variable resistor 21. Moreover, such a setting operation of the variable resistor 21 can be performed without actually seeing the brightness of the lighting fixture 2.

Effects As described above, according to the present invention, the ratio of power consumption to the rated power of the load is
It becomes possible to control the desired power consumption without being affected by the length of the line that supplies power to the load.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of the prior art, FIG. 2 is a waveform diagram for explaining the operation shown in FIG. 1, FIG. 3 is an electric circuit diagram of an embodiment of the present invention, and FIG. 4 is a waveform diagram for explaining the operation shown in FIG. FIG. 7 is a waveform chart for explaining the operation of the embodiment shown in the third figure. 1...Fader, 2...Lighting equipment, 6...AC power supply. 11...Triac, 14...Current transformer% 15.
... Rectifier circuit, 18 ... Multiplier, 21 ... Variable resistor, 23 ... Comparator, 27 ... Continuity angle control circuit Agent Patent attorney Kei Nishi

Claims (1)

[Claims] A switching element interposed in series with a load energized by AC power. Means for detecting load current Kk. Means for deriving a control current representing a ratio of power consumption to the rated power of the load. means for deriving a detection signal representing a ratio of power consumption to the rated power of the load in response to the output from the load current detection means; 1. A load control device comprising: means for comparing a control signal and a detection signal, and changing an energization angle of a switching element so that the detection signal matches the control signal.