Design And Research Of Photovoltaic Power Supply DC/DC System

With the development of economy and society,energy consumption of human increases day by day,the contradiction between economic development and environmental protection has become increasingly acute.As a big country of economic development,China's energy problem is particularly prominent.The exploitation and utilization of new energy has become the direction of this problem,and as an important new energy,the solar energy occupies a pivotal position in the economic society.At the same time,with the DC electrical appliances,DC electric vehicles and other DC load of the wide range of applications,DC power supply has become the trend of social development gradually.But,at present,there are some problems such as high cost and low efficiency in the photovoltaic DC power supply.So,the photovoltaic power supply DC/DC system will be studied and designed in this paper,and these problems will be solved in the system.Firstly,the structure of photovoltaic power supply DC/DC system is designed,the model in the system is analyzed.At the same time,the essential control strategy is be researched in the system,for the miscarriage,shock,the tracking precision and response speed can not be balanced and other defects of common MPPT methods,this paper proposed an adaptive variable step size P&O MPPT method based on hysteresis control,and the simulation results show that the algorithm is effective.The method not only can solve the algorithm defects,it but also can improve the stability and efficiency of the system.Secondly,the overall energy management strategy of the system is studied,and the energy flow of the system is regulated.Based on the variation of the DC bus voltage,the voltage hierarchical control strategy is proposed,voltage layered droop control is be used.In different working segment,each controller is coordinated to ensure the energy balance and the stabilization of DC bus voltage.At the same time,in consideration of the special load,such as DC charging pile,when there is a DC electric car charging through the DC charging pile in the system,the DC electric vehicle has the priority of charging,under the premise of ensuring important load power supply in the system.Finally,a small power experimental model based on DSP28335 is built to verify the correctness of the proposed control algorithm.The main control circuit,sampling circuit,driver isolation circuit,other auxiliary circuit,etc.is designed,also,the main program,the solar constant voltage drop program,the improved MPPT control program and the energy storage system for charging and discharging procedure software program,etc.is designed in the system.