Research And Implementation Of Photovoltaic Array Simulator Based On DSP

As the important part of a photovoltaic system,the photovoltaic array is the basics of the key technology of photovoltaic systems,such as in the respects of maximum power point tracking,photovoltaic grid-connected inverters and photovoltaic charging stations.The output characteristics of the actual photovoltaic array are easily affected by the external environment,and it is difficult to play its role in the experimental stage.The use of photovoltaic array simulators can greatly shorten the development cycle of photovoltaic power generation equipment,reduce related costs and improve research and development efficiency.Firstly,this article introduces the development status of the photovoltaic industry,clarifies the research value and significance of photovoltaic array simulators.The paper proposes a method for simulating the output characteristics of photovoltaic cells,which can reduce the difficulty of endpoint selection during segmented fitting.By the analysis and deduction of the conduction states of the bypass diode and the isolation diode,a mathematical model of the photovoltaic array considering the voltage drop of the diode is established to realize all-weather simulation.The typical faults of the photovoltaic array are analyzed,and the photovoltaic array model in the cases of open circuit,short circuit and aging failure are built to simulate typical faults of photovoltaic array.Secondly,the design and optimization of the simulator topology and control strategy are given.The working process of the ZVS phase-shifted full-bridge is analyzed in detail,and the conditions for achieving ZVS with the leading arm and the lagging arm are deduced.The resonance process of the secondary rectifier junction capacitance is analyzed,and the Tr-Lag clamp diode is used to suppress the resonance spike.In order to improve the efficiency of the simulator,a synchronous rectifier MOSFET is used to replace the rectifier diode,and the driving waveforms and selection conditions of the three working states of the synchronous rectifier MOSFET are analyzed.Different control modes are proposed for different simulation objects.The small signal model of ZVS phase-shifted full-bridge converter is built,and PI compensation network is used for loop compensation.The delay problem caused by ADC sampling is optimized to reduce the system control delay.Finally,the hardware platform is built with TMS320F28335,the code generation of CCS project is realized by PSIM.A design scheme based on the isolation measurement module for power conversion system test is proposed,which can reduce the test cost and improve the test accuracy.The experiments are carried out on this experimental platform to simulate the output characteristics of the photovoltaic array under the conditions of uniform illumination and mismatch phenomena.The feasibility of the designed topology and control strategy is verified.