Led Street Lamp Lighting System

In recent years, the LEDs as a new light source is arousing more and more interest, especially the LEDs expand its field of application from the indication and landscape lighting to the demoestic lighting, to replace the traditional incandescent lamp, fluorescent lamp,and gas discharge lamp as light source. How to provide a power driver which fit the properties of the LEDs to meet the needs of demoestic lighting, is naturally becomes a research hotspot. This paper attempts to put forward a modular LEDs power dirver based on the traditional ones.First this paper introduces the application background and prospects for the development of the LEDs, especially the huge domestic lighting market and the preferential policies which supplied by our country. And further informate the characteristics of the LED, including the lighting principle, the electric characteristics and the thermal properties. Secondly, it cite the power supply type, the connection and the dimming methods of the LEDs, then the advantages and disadvantages of LED lighting.This paper described the process of building the power supply. The fly-back converter which applicate the primary side feedback technology (PSR) supplying constant voltage to three independent constant current source module which support the LEDs,those modules with short circuit protection,output overvoltage protection and overtemperature protection. Then analysed how the power supply works, the system stability and the dynamic response. Small signal model of the fly-back converter is established. Detailly analysed the principle of the PSR technology.which different from the traditional method of using optocoupler lement, it obtain voltage information from the auxiliary winding instead of secondary winding. Also introduced how the PSR maintain constant voltage and constant current state, and how to transform each other.In the following, this paper introduced the design and implementation fo each functional circuits of the power supply,including the switched circuit,the constant current source circuit,the dimming circuit.Finally, the small signal model of the fly-back converter has been constructed, then the LEDs power driver has been verified by a simulation, and a prototype is constructed and tested, experimental results are presented to verify the stability and effectiveness of it.The paper mainly includes the finished work of the following sections: (1) In-depth research on the LEDs:the lighting principle, the electric characteristics and the thermal properties. the power supply type, the connection and the dimming methods of the LEDs(2) Combining the characteristic of LED, this paper constructs the LEDs power dirver, then introduced how it works,and its stability and dynamic response.(3) Introduced the design and implementation fo each functional circuits of the power supply.(4) The small signal model of fly-back converter has been constructed, then verified by the simulation and the prototype.