Research And Design For Single-stage PFC Flyback LED Driver Control Loop

After the experience of world-warming and the lack of resources, low-carbon green environmental now become an irreversible trend energy development. researchers continue to pursue limit of technology in the lighting field, light-emitting diode(LED) successfully applied in the daily lighting environment has attracted a lot of attention. As a solid-state light source, LED lighting’s features such as green and energy saving, long-life, safe-using, reliable and flexible design that will gradually replace the other sources to become a leader in the field of lighting.Experienced ten years of continuous development, LED drivers as a key link of LED lighting technology, spans from immature into today’s universal application, has played a significant role in the popularize of LED lighting. however, before the technical pace is never-ending, LED controller is developing toward the direction of simplistic and functional. Universality of lighting needs demonstrates its huge base in the application, in the international or national harmonic standards the power threshold for the electrical equipment become increasingly lower, those LED lighting equipment with power factor correction(PFC) function undoubtedly has great practical value.This paper studies and analyzes of a single-stage PFC flyback LED driver control loop, circuit uses a flyback converter topology, use voltage follower control technology to achieve power factor correction function, regulates on-time of switch MOSFET by voltage error comparator that change power delivery from input side to the output to stabilize the output current, in other assistive technology, drawing on the primary side feedback technology to achieve feedback control loop, as well as quasi-resonant detection technology to achieve soft-switch for switching MOSFET that improve energy efficiency.The paper firstly analyze the basic principle of a single-stage PFC implementation, then research and analysis the theoretical basis of the implementation of a single-stage PFC flyback LED driver control loop in determinate circuit architecture, for each of the main aspects of the control loop, some circuit module has been designed including the inductor current sampling, voltage pretreatment, the voltage error amplifier, on-time modulation, the inductor current fall time detection and quasi-resonant detection and so on, and make the simulation and analysis for functional and performance of the above circuit module, at last converged the above major modules into the overall system circuit using HSPICE simulation tool to verify the design.