A High-power-factor Flicker-free LED Driver Research

In recent years,with the global energy problem becomes more and more serious,energy saving and environment-protecting have become growingly significant.As the fourth generation lighting,LED lighting has been used increasingly widely because its lower energy consumption,longer service life,higher security,etc.As the core part of the whole LED lighting system,the LED drive power supply which is of lower cost,higher reliability,higher power factor and no strobe flash is required to be developed ceaselessly to meet the needs of prospect of LED lighting technology development.This is going to be have profound significance.The research of high power factor without stroboscopic LED drive power.First of all,in order to improve the power factor,the characteristics of active PFC(power factor correction)circuit topology and inductor current control mode were analyzed,determined by single stage flyback topology as the LED driver's PFC stage,and the inductor current worked in the intermittent mode,to achieve high power factor.Secondly,due to the AC power supply,single stage active PFC technology will cause the LED output current with two times the power frequency component,triggered LED lighting stroboscopic effect.In order to solve this problem,this thesis based on the main structure of flyback converter,improve a new circuit structure,the secondary side of the transformer is the energy balance circuit consist of two coils,power tubes,diodes and capacitors,to balance the difference between the input power and output power by small capacitance instead of electrolytic capacitor.the capacitor release of energy,to achieve constant power output,and analyzed the principle of the control circuit.At the same time,increased the strobe elimination module between former driver and load,design the peripheral circuit by strobe eliminating chip,acquisition of load current into voltage,compared with the capacitor voltage in the peripheral circuit,then through the chip to control the LED output current,to eliminate the LED output ripple current.Finally,according to the design index,analyzed and designed of the relevant device parameters in the circuit,then validated this scheme by the experiment.Measurement data show that,added the active power factor correction technology,power factor improvement,the LED driver's overall performance is better,the proposed scheme can solve the flicker problem,proved the feasibility of high power factor without stroboscopic LED driver.