1 Introduction
With the development of China's economy and society, lighting power consumption has accounted for 10% to 12% of total electricity consumption. Lighting energy conservation has become an important aspect of energy conservation and environmental protection. The purpose of lighting energy saving is to reduce the energy loss in the lighting system and to make the most efficient use of electric energy under the premise of ensuring the lighting scale and lighting quality.
The mainstream lighting energy-saving technologies include energy-saving lighting sources (such as LED lighting) and energy-saving circuits (such as dimming circuits, energy-saving switches), and the comprehensive application of these two technologies is a new trend of lighting energy-saving technology. In China, the development prospects of LED lighting equipment are good, but the existing energy-saving circuit technology generally has the following two shortcomings:
(1) Most of the dimming circuits are composed of chips such as single-chip microcomputers, and the cost is high, which is not conducive to installing and replacing the original circuit;
(2) The energy-saving circuit is relatively complicated. When installing related equipment, it is necessary to make major modifications to the original lighting system in indoor or other application places. The installation and maintenance costs are relatively high, and the implementation is difficult.
In view of the above shortcomings, this paper designs and implements a general-purpose intelligent switch with low cost, miniaturization, environmental protection, energy saving, easy installation and maintenance for LED lighting equipment, using simple components commonly used in analog and digital circuits.
2. System circuit and working principle
2.1 Working principle
The LED intelligent switch designed in this paper mainly includes two parts: intelligent control circuit and intelligent dimming circuit, as shown in Figure 1.
The intelligent control circuit interface C and D are connected to the control circuit which can be turned on and off according to the illumination intensity. The control is mainly completed by the thyristors D1 and D2; the intelligent dimming circuit interfaces A and B are connected to change the thyristor with the illumination intensity. The control circuit of the conduction angle. The working principle of the intelligent switch is shown in Figure 2.
2.2 Intelligent control circuit
The intelligent control circuit can automatically turn the light on and off according to the brightness set by the user. The circuit connected to the C and D interfaces (see Figure 1) is mainly composed of LM339 and 74LS02, as shown in Figure 3.
Among them, the resistance value of R6 can set the sensitivity of the switch according to different environments, and LM339 mainly compares whether the voltage across R5 is between the voltage across the photoresistor and the voltage across R6; 74LS02 mainly replaces the result of comparison with high and low voltage. Flat, and then through the triode and relay to control the conduction and shutdown of the thyristor; adjust the adjustment knob 1 to set the brightness limit reached by the continuous on and off lamps. The intelligent control circuit mainly controls the lighting device to be brightened and extinguished by controlling the on and off of the thyristors D1 and D2 (see FIG. 1). The working principle is shown in FIG. 4.
2.3 Intelligent dimming circuit
When the LED lighting device starts to work, the intelligent switch designed in this paper will automatically change the brightness of the lighting device through the intelligent dimming circuit according to the change of the ambient lighting condition. The circuit of the intelligent dimming circuit interface A and B shown in FIG. 1 is shown in FIG. 5.
The user conveniently adjusts the brightness that the environment needs to maintain by means of the adjustment knob 2; the intelligent switch automatically changes the brightness of the LED lighting device according to the set brightness and the change of the actual ambient light intensity to maintain the set brightness requirement. Play a role in energy saving.
The working principle of the intelligent dimming circuit is shown in Figure 6, where the change of the resistance value of R19 causes the oscillator frequency to change, and this frequency change can change the charging time of the capacitor C3, and the resulting sharp pulse can control the conduction of the thyristor D13. The angle of intersection, in turn, controls the effective voltage across the luminaire to achieve the purpose of controlling the change in brightness of the luminaire.
3. Work performance testing and analysis
In order to test the actual working performance of the intelligent switch designed in this paper, the author built a test environment indoors.
The environment is kept in line with the outdoor brightness through a transparent glass window, and the change in outdoor brightness is simulated by artificially blocking the light entering the room. The brightness of the light that needs to be maintained indoors is set between 40lx and 50lx. The simulated outdoor ambient brightness, the actual brightness of the room, and the actual brightness of the LED light are measured by a photosensor. The experimental curve shown in Figure 7 is the average of the results of repeating more than 20 experiments in the same configuration environment.
The curve shown in Figure 7 shows that when the brightness of the outdoor ambient light gradually weakens, the intelligent switch of this paper can automatically adjust the brightness of the LED light to make it gradually brighten, so that the brightness of the indoor light remains within the preset range. . Similarly, when the brightness of the outdoor light gradually becomes stronger, the smart switch can control the brightness of the LED light to gradually darken to maintain the preset indoor brightness. It can be seen that the use of the intelligent switch designed in this paper can save the power consumption of the LED lamp while maintaining the brightness of the room.
4 Conclusion
This paper proposes a design scheme of a universal intelligent switch based on LED lighting equipment. The scheme integrates simple analog circuits and basic components of electronic circuits, and designs and implements a smart switch suitable for LED lighting equipment. The working performance of the smart switch was tested experimentally. Different from the intelligent switch based on single chip microcomputer, the intelligent switch of this paper has the following characteristics: 1 pure hardware circuit implementation, no need for software programming and setting during manufacturing and use; 2 simple operation and control, simple installation, easy to use; 3 low cost switch Suitable for occasions with high cost control requirements.
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