Research On Multi Mode Quasi Resonant Flyback Converter With Power Factor Correction

With increasing environmental and energy saving concerns, Countries around the world have established related standards which demand the switching mode power supply (SMPS) to maintain high energy conversion efficiency and low input current harmonic content over wide ranges of operating conditions. Hence, the research on "green" power supply with low harmonic content and high energy conversion efficiency has become an important research topic in the field of power electronics.On the basis of reading related literature, this paper puts forward a two-stage circuit scheme. The front-end adopts Boost-PFC in critical conduction mode. The function of the power factor correction is realized. It makes the converter meet the International Electrotechnical Commission IEC61000-3-2harmonic limit requirements in a wide range of input voltage (85VAC-265VAC). And the zero voltage switching (ZVS) of the power switch can be achieved, so the switching loss of the switch can be reduced. The back-end adopts multi mode quasi resonant flyback circuit topology. By the quasi resonant soft switching technology. Turning on the power switch on the valley of the drain voltage is realized, the loss of turning the power switch on is reduced. With the load reduction, the converter can operate in frequency foldback mode and green mode, in turns. Multi-mode controlling of the converter is realized, the energy loss of the converter is reduced. Maintaining high energy conversion efficiency is achieved in various load conditions.Firstly, this paper summarizes the development of the power factor correction technology and high efficiency of the switching mode power supply. Then, the working principle and control strategy are analyzed both the power factor correction circuit and the multi mode quasi resonant flyback circuit, respectively. On this basis, all the parameters of these two-stage converters are derived and calculated. A120W(12V/10A) switching mode power supply experimental prototype is devised and manufactured. Finally, in order to verify the feasibility of the circuit design, the relevant performance testing is carried on with this prototype, and the relevant experimental waveforms are recorded and analyzed.