Research Of Cross Flyback Photovoltaic Equalizer Based On SiC MOSFET

In recent years,the traditional energy sources tend to dry up,environmental deterioration is increasingly serious.In this context,clean energy solar energy as the source of photovoltaic industry has been rapid development.The energy output of photovoltaic module is reduced and the energy loss is caused by production error,shadow shadowing and uneven illumination in the process of photovoltaic power generation.The output energy can be improved by optimizing the structure of photovoltaic module.In this paper,photovoltaic energy equalizer based on wide band-gap devices is studied.By comparing the advantages and disadvantages of each power optimization structure,the series self-compensation structure is selected as the equalization structure of photovoltaic equalizer.For the research of SiC MOSFET,a new model based on physical model and analytical model is proposed in this paper.The model is analyzed and verified,which provides the theoretical basis and applied reference value for the design of driving circuit and peripheral circuit of SiC MOSFET.The physical characteristics and switching characteristics of SiC MOSFET and Si MOSFET are compared,and the high temperature resistance and low loss of SiC MOSFET are verified by experiments.In this paper,the main power circuit-Cross Flyback topology circuit is deeply studied,and the realization of ZVS technology of the system is designed,the loss of the system is reduced.By using the high frequency characteristic of the new wide band gap device SiC MOSFET and the interleaving control strategy,the working frequency of the system is improved and the miniaturization of the system is achieved.Due to the advantages of digital control system in speed,precision,cost-performance and so on,this paper chooses the digital control mode based on Digital Signal Processing(DSP).According to the derived system small signal model,the compensator is designed by using MATLAB,on the transfer function of the system.Finally,a photovoltaic equalization experimental platform is built in this paper.The experimental results of the staggered-parallel Flyback converter and the equalization system are carried out and the experimental waveforms are obtained.The output of the simulation circuit based on the new SiC MOSFET model is consistent with that of the simulation circuit.The energy balance is achieved and the correctness of the model is verified again.In addition,in the equalizer based on Si MOSFET and SiC MOSFET,the efficiency of equalizer based on SiC MOSFET is increased by 4.1%.