The Study And Design Of High Power Factor In LED Driver

The electric consumption on lighting accounts for almost one fifth of the global electricity consumption.As the fourth generation light source, LED has many advantages, for example: high luminous efficiency, long life, safer and more environmentally friendly, so it is widely used in many fields.The paper takes high power factor LED driver as the topic and studies the two-stage PFC converter deeply.Fistly, the paper introduces the topological structure and typical control strategy of active power factor correction(APFC) in detail. The design process of the Boost APFC circuit,including EMI filters and rectifier circuit、the main circuit of Boost APFC and the control circuit which uses L6562 as the core component are given.During the design process,the calculation and selection criteria of the related components are given.An optimization method for the safety circuit and surge suppression circuit of the Boost APFC circuit is proposed.Through this method,we can not only improve the lighting protection capacity, but also improve the surge handling capability when the driver operates at continuous on-off state.Secondly, on the basis of comparing the four kinds of resonant converter,the paper selects half bridge LLC resonant converter as the topological structure for DC/DC circuit.The paper uses first harmonic approximation(FHA) method to study the gain characteristics of the half bridge LLC resonant converter.It analyses the impact of quality factor Q and inductance ratio m on the DC voltage gain.Based on the theoretical analysis,we design the main circuit and control circuit for the half bridge LLC resonant converter.Using the Saber simulation software, the parts gallery model of L6599 is built.With the model,a time domain simulation of the whole LLC resonant circuit is constructed and the simulation results prove the effectiveness of the model and design.At last, based on the theoretical analysis and simulation, a 180 W prototype is built.Then we test the prototype and the experiment results verify the effectiveness of the theoretical analysis and the design.