A Led Driver Based On Energy Channeling And Energy Feedback Method To Achieve Sing-stage Electrolytic-capacitor-less Flicker Free Operation

As a new generation of electro-optic source,light-emitting diode(LED)is widely used in various lighting occasions because of its long service life,high efficiency,small size and environmental protection.LED bulbs need constant DC current support to produce stable lighting.Therefore,LED driver is the most critical part of the whole LED lighting fixture,which determines the quality of lighting and seriously affects the sales price,daily expenses and service life of the whole lighting equipment.Single stage LED driver is popular in the market because of its low cost and efficiently.When the the conventional single-stage grid connected LED driver achieving high power factor,it needs to add large capacity electrolytic capacitor to the output side to limit the double power frequency current ripple which causes the LED light flicker.However,the life of the electrolytic capacitor is far less than that of the LED lamp.In the LED driver,the application of the electrolytic capacitor will reduce the service life of the whole lighting equipment.Therefore,the design of a high efficiency,low cost,no flicker,and no electrolytic capacitor single-stage LED driver has become a research hotspot.This paper presents a single-stage LED driver based on energy channeling method and energy feedback method.The LED driver adds a ripple cancellation circuit in series with the traditional flyback circuit.The ripple cancellation circuit can output an AC ripple elimination voltage to offset the total voltage ripple,so as to realize the LED flicker free operation without using electrolytic capacitor.The LED driver has two working modes of energy channeling and energy feedback.When the output ripple elimination voltage is positive,the LED driver works in the energy channeling mode to realize single-stage energy conversion.When the ripple elimination voltage is negative,the LED driver works in the energy feedback mode and feeds back less than 4% output power to the input side.The LED driver has the advantages of low energy multiple conversion ratio and little power semiconductor devices,making its efficiency close to the real sense of single-stage LED driver.Finally,a 35 W(100 V,0.35 A)experimental platform is built to verify the effectiveness of the scheme.