The LED Driver Circuit Design With Intelligent Control

Although, LED lighting has been widely used recently, it still exist some problemson the LED driver, such as unconformity homogeneity of the quality, low efficiency,low reliability, bad electro magnetic compatibility(EMC). So, the research anddevelopment of high-power LED driver with good EMC is very significance fortheoretical study and practical application.This dissertation analyzes the working principle of the high-power LED drivercircuit. Comparing two-stage active power factor correction (PFC) with single-stagePFC. It can be categorized as either two-stage PFC or single-stage. Two-stage of thePFC circuit includes a PFC stage and a DC/DC stage which have been widely used innotebook adapter. Single-stage PFC circuit is integrated with PFC stage and DC/DCstage that makes topological structure simple and cost-down. And they are suitable forlow-power applications. Only the isolated can meet the requirements of LED drivercircuit. So the single-stage PFC are obviously better suited that with lower cost andhigher power factor. By farther research, we made some improvements on thesingle-stage PFC circuit of flyback topologic structure.In this dissertation, we adopted single-stage PFC topological structure, in themean time, it required high-power factor correction, constant current and limitingvoltage feedback controlling etc. We designed a LED constant current feedback circuitto meet the requirements of this special circuit by analyzing this special structure of thesingle-stage PFC circuit. The heating problem of the circuit has been fully considered.Excellent heating dissipation can improved the performance of the circuit.Through analysis the high efficiency, low EMC, low temperature rise, suitablecircuit for single-stage PFC flyback structure, the working principie of single-stage PFCflyback transformer, we designed and produced a kind of transformer that hasadvantages performance when it used in switching power supplier.This dissertation introduces the design of a street lighting system with threeconstant current outputs. The system utilizes flyback topology to meet the function ofisolation between input voltage and output voltage and power factor correction (PFC).The system adopts twostage structure, one is to realize the function of isolation betweeninput voltage and output voltage and power factor correction (PFC), Another stage is designed to realize three independent constant current output. In the normal inputvoltage (AC185V-AC250V), the power of the system is up to100W, the efficiency isup to87%, and power factor (PF) is also corrected to morethen0.98. Furthermore theoutput voltage ripple is less than5%. And, this system also has the function ofautomatic dimming and shutdown.