Study Of A Novel Single-stage High Power Factor LED Driver Based On LLC Converter

With the continuous advancement of science and technology,people's living standards are constantly improving,resource consumption is also increasing,and energy consumption problems are coming one after another.How to improve energy efficiency has become a major problem in contemporary society.LED as anew type of lighting technology in the new era,with high luminous effieiency,low loss,green pollution-free,long service life and other characteristics,can be applied to lighting,signal lights,computer monitors and other fields to alleviate energy The problem of consuming too fast.The driving circuit is the key to LED.Therefore,the research of LED driving circuit has become a hot spot in recent years.Firstly,this paper briefly introduces the LED and its driving circuit,and analyzes the advantages and disadvantages of the two-stage and quasi-single-level driving circuits.Based on the above analysis,the working mode of the two-stage Boost+LLC driving circuit is introduced,and the pre-Boost PFC circuit and the post-LLC circuit are respectively deduced and formulated,and a 60W prototype is developed,then the waveform and data are analyzed.Compared with the two-stage circuit,this paper introduces the quasi-single-stage Boost+LLC driver circuit,analyzes its working mode and its advantages and disadvantages,then a control method using the PWM/PFM hybrid control to reduce the bus voltage is introduced,the advantages and disadvantages of the circuit under this control mode are analyzed.Finally,the principle of the circuit and parameter design of this circuit are introduced,a 60W prototype is built,and the experimental results are analyzed.Based on the problems discussed above,this paper proposes a converter that can realize soft-switching and high-power factor.The converter makes the inductor current resonate through the resonant capacitor,which can realize the zero-voltage turn-on of the switching devices.Based on this topology and LLC resonant converter,a new quasi-single-stage high-power-factor converter is proposed.The circuit has a lower bus voltage during the working process,and the converter is analyzed and calculated by the principle of power balance.The relationship between the bus voltage and the pre-resonance parameters is derived.The reasonable pre-resonance parameters are selected,and a 60W prototype is built to verify the feasibility of this converter.At the end of the paper,the experimental results of three prototypes are compared,and their advantages and disadvantages are analyzed.