Research On A Kind Of LED Control Circuit With Constant Illumination

LED lamp with adaptive ambient light technology is the direction of development of LED lighting technology in the future. However, with the development of economy,energy demand and consumption continue to increase, and the traditional lighting methods are difficult to meet the development requirements already. Light waste and light pollution problem is exposed gradually because of large area of the use of LED lights. A high quality, intelligent LED drive power should have the function of higher light utilization, reduce the role of light waste and light pollution.This article designed a LED drive power with constant illumination intelligent control. The drive power supply has the function of automatically adjusting the output power according to the change in illumination of the ambient light. It can reduce the output power when the ambient light is strong, which makes current ambient light constant. This makes full use of the sun and other ambient light, and reduces the energy of the waste and the damage to the human eye of strong light. The drive power supply is particularly suitable for use in commercial lighting, public area lighting, office lighting and other occasions.In this paper, a kind of constant illumination LED control circuit is studied theoretically, including the aspects of driving power supply design, light detection and control circuit and software design. A prototype is designed to verify the theory. The main tasks of this thesis are as follows:1. In the aspect of basic knowledge, this paper introduces the structure and characteristics of LED light source, the basic concept, the common driving method,the lighting dimming method and the realization method of constant illumination,and then introduces the common topology, working mode and control mode of switching power supply.2. In the aspect of hardware design, a constant current quasi-resonant flyback switching power supply circuit is designed. Making it as the main structure, the secondary use two loop feedback ways. The first way is to detect the output current,feedback to the primary after comparing and amplifying, so that the converter works in a constant current state. The second way detects the output voltage so as to limit the output voltage in no-load conditions. The output current can be adjusted by adjusting the magnitude of the current feedback signal to adjust the output current.A light sensing circuit and a MCU circuit are designed correspondingly in this paper.3. In the aspect of software design, through the analysis of the principle of constant illumination, the corresponding system control program is written, which realizes the function of light intensity detection, manual dimming and output power regulation. After repeated comparison, it is determined that the control strategy can be used to control the system quickly.4. After theoretical analysis, the schematic and PCB are drawn and an experimental prototype is designed. After testing the prototype, it perform excellently, such as high efficiency, accurate constant current, stable luminous power and quick light intensity adjustment and so on, which verifies the design ideas and methods, and meets the design requirements.