Study On The Key Issues Of Photovoltaic Power Converter Using SiC Devices

The research object of this thesis is SiC photovoltaic power converter.From the control,device and whole machine perspective,this thesis studies the following key issues through theoretical analysis,simulation,experimental verification and other methods: the maximum power point tracking problem,SiC device loss analysis and machine design issues.The traditional power tracking algorithms such as observation disturbance method are analyzed and simulated in this thesis,and the observation disturbance method can effectively track the maximum power under the condition that the PV array is not occluded.The application of particle swarm optimization(PSO)in power tracking is studied.At the same time,in order to overcome the problem of poor real-time performance of particle swarm algorithm,this thesis introduces the inherent characteristics of PV array into particle swarm algorithm initialization process,which significantly reduces the tracking error of the algorithm.The influence of parasitic inductance,nonlinear capaci tance and temperature on the loss of SiC MOSFET is analyzed in this thesis,and the Ltspice simulation experiment is designed.The experimental results show that the parasitic inductance value significantly affects the SiC MOSFET switch ing process and loss.This thesis also builds a double pulse experimental platform to measure and analyze the real switching process and loss of SiC MOSFET.A two-stage SiC MOSFET driver circuit is designed in this thesis.The drive voltage is generated by the push-pull and voltage booster circuit in the drive voltage generation stage.The drive voltage output stage first uses the optocoupler chip to isolate the drive signal,and then outputs the drive voltage by the totem pole buffer circuit which connects with the preceding stage.This thesis designs a photovoltaic power converter system,and build s a hardware experimental platform.According to the experimental results,the theoretical loss and measured loss of the power converter are compared and analyzed.When the input voltage is constant,the loss of the power converter system increases as the output load increases.When the output load is constant,the loss of the power converter system decreases as the input voltage increases.