Design And Implementation Of Dimmable LED Driver Power Supplies

LED is called the fourth generation of green lighting source, with the advantages of small power consumption, high luminous efficiency, long service life, safety and credibility, LED lighting has been gradually replacing traditional lighting and LED is widely used in many fields. However, the current LED drive power supply has low efficiency and an unstable current-output which shortens the life of LED and seriously affects the development of LED. In addition, in order to respond to the call of energy conservation and environment protection, if we can achieve intelligent dimming of LED, not only can save energy, but also extend the service life of LED.According to the design requirements of LED driver power supply, a LED driver power supply with active power factor correction circuit (APFC) and forward circuit two level structure and dimming function is designed.Firstly, the characteristics, principles, parameters of LED and DC/DC circuit topology are studied, and the APFC circuit is compared and analyzed. According to the design requirements and specifications, the monolithic construction of LED power supply system is designed.Secondly, considering the practical application, the input protection circuit,electromagnetic interference filter (EMI) and heat dissipation device are designed to improve the safety and reliability of the power supply. In order to improve the power factor and efficiency, the APFC circuit is designed by using ICE3PCS03G and the forward circuit is designed by using NCP1252. Two types of the LED constant current drive circuit are designed by LM7809 and LM3404HV.Thirdly, on the basis of studying the dimming principle, the light-adjusted system which based on ATmega128 is designed, and the minimum system of ATmege128,temperature acquisition module, illumination acquisition module and the infrared monitoring module are designed.Finally, the PCB board of LED power supply is fabricated and the main performance parameters are tested, the power factor is above 0.95, the efficiency is more than 85%, the power factor and efficiency are improved greatly. The light-adjusted system is tested under the existing conditions of the laboratory. The test results show that the LED drive power supply and the result of dimming is satisfactory.