Home Lighting Research Power LED Drivers

In the field of lighting incandescent bulbs because of its big power consumption, short service life, performance is far lower than the other new type of light source gradually eliminated by countries. LED lamp is a new type of lighting products called "green lighting" light source, has a development potential. The drive power supply is a key factor restrict LED lights access to the field of household lighting, when designing the LED driver power supply should be considered the volume, efficiency, power factor, the effect of constant current constant voltage and other factors.This paper analyzed the characteristics of the LED and the drive’s requirements,and made a summary of the current situation and development about LED drivers.Based on this theory,this paper designed a two-stage LED drive power supply,its PFC stage adopts boost topology,DC/DC stage adopts quasi-resonant flyback topology. The switches of the DC/DC stage and PFC stage were centralized control by a controller iw3614. Prototype made quasi-resonant opened, constant voltage and constant current, and other related experiments. The results show that the power supply has the advantages of simple structure, good constant voltage constant current characteristics, small loss, high power factor.The main contents of this paper are as follows:(1) A two-stage circuit topology was chosed as the main framework of drive power supply, and selected the appropriate circuit topology for PFC stage and DC/DC stage respectively.Each performance index of the drive power supply are given, and the iW3614chip power factor correction principle was introduced in detail. While the dimming circuit was designed for the power supply with better application in the field of household lighting.(2) The basic principle of the primary side control to ensure power supply constant voltage constant current output was analyzed. The operation mode of the quasi resonant flyback circuit was introduced, and how to reduce the switching loss was analyzed. The high frequency transformer, RCD absorbing circuit and anti-EMI circuit was designed.(3) The iW3614chip was choosed as PFC circuit and DC/DC circuit’s control chip. The function of each pin and internal structure of the iW3614chip were briefly introduced.(4) The related experiments have been conducted on the design of power supply prototype, the results show that the designed LED driver power supply can meet the requirements. It has small volume, high efficiency, constant current constant voltage output effect was good, high power factor and so on.