High Efficiency LED Driver Study

When the problem of energy shortage is worsing and the demand of environmental protection is increasing, countries around the word start focuse on the development of green efficient lighting. With its high efficiency, energy saving, environmental friendliness, long lifetime, safety and reliability, high-brightness LED (Light Emitting Diode) will serve as a revolutionary energy-efficient lighting technology in different areas and gradually become the first choice for lighting. The rapid development of LED technology also makes LED driving a hot study spot.According to the application demand of LED lighting, this article proposed a two-stage LED driver. First, a detailed analysis of power factor correction's working principle which based on L6562A and works atTCM mode was given out, the design process and methods of main parameters of LED driver and control circuit was shown at the same time. Then in chapter 3 it analyzed the characteristics of LLC resonant converter under different frequencies, discussed the influence of main parameters by setting up a first harmonic approximation model, it also provides the design process of resonant network and control loop in detail. Finaly, experimental results was shown by testing a wild range voltage input (85V-265V/50Hz), 0.6A/96V output LED driver model, results indicates that the LED driver was design with strong feasibility and rationality.In addition, because of the use of short-lifetime electrolytic capacitor in power factor correction converter, lifetime of LED lighting driver is far less than the LED light source. This problem has affected the wild application of LED lighting technology. Therefore, this article proposed a non-electrolytic capacitor power factor correction converter. By analyze the role of electrolytic capacitor plays and the factors which decide the electrolytic capacitor's size, it offers the method by injecting the third time harmonic current into the reference signal to help decrease the capacity of ouput capacitor. Then electrolytic capacitor can be replaced by film capacitor.