Research On High-Gain PFC Converter Based On Digital One Cycle Control

High gain power factor correction(PFC)is commonly used in electrostatic generator,high voltage LED,X-ray and new energy.Its output voltage gain is much higher than that of conventional PFC converter,so it needs to adopt high gain topology.OCC has the advantages of no multiplier,no sampling of input voltage,simple structure and fast response,but it is sensitive to the ripple and noise of the sampled current.The circuit structure of high gain converter is more complex,and its input current waveform often presents resonant or quasi resonant,or even AC characteristics.Therefore,how to select and improve the topology and select the appropriate current sampling algorithm has important research value and significance for improving the performance of PFC converter with OCC.This paper takes the high gain PFC converter as the research object.Firstly,the topology selection method of high gain PFC converter is discussed.Combined with the digital OCC,the number of switches,component stress,inductance,voltage gain,efficiency,the complexity of system loop transfer function and whether there is disturbance in input current are seven dimensions to evaluate the topology performance of single-stage converter,and one of the better schemes is selected.The steady-state analysis,circuit parameter design and closed-loop controller design of the high gain PFC converter are completed.Finally,the correctness of the theoretical analysis is verified by simulation and experiments.Then,this paper studies the two-stage high gain PFC converter,focusing on the performance improvement method of its front-stage PFC converter.Combined with digital OCC technology,a zero current ripple PFC converter is proposed.Then it makes a theoretical analysis,deduces the realization condition of zero current ripple,and gives the main circuit parameters and the design method of closed-loop compensator.Finally,the correctness of the theoretical analysis is verified by simulation and experiment.Finally,three experimental prototypes are built and verified by experiments.The experimental results show that when the AC input is 85 Vrms ～ 265 Vrms and the output power is 200 W,the PF is greater than 0.99,the THD is less than 5%,the output DC voltage can reach 800 V,and there is no large voltage spike at both ends of the switching device.Compared with the traditional Boost PFC converter,the proposed zero current ripple PFC converter has significantly reduced volume and weight,almost zero input inductor current ripple,stable output DC voltage at 400 V,PF greater than 0.99,THD less than 3.85% and maximum efficiency of nearly 97%.To sum up,this paper takes the high gain PFC converter as the research object,adopts the OCC strategy,studies and puts forward the selection method of high gain PFC topology.Combined with an example,the theoretical analysis is completed,and the performance of the proposed single-stage high gain PFC converter is verified by simulation and experiment.On this basis,a new zero current ripple PFC converter solution is proposed.By reducing(eliminating)the current ripple of the input inductance,the performance of the OCC PFC controller can be effectively improved.The converter can be widely used in various high gain PFC applications.