| Nowadays，energy and environment are two major issues in the world.After coal, oil, natural gas and other fossil fuel largely mined, many countrieshave been focusing on the research and development of renewable energy. Solarenergy has the characteristics of renewable and clean, which is inexhaustible insupply and always available for use for human beings. So solar energy usedwidely at home and abroad, which has become the mainstream of the worlddevelopment trend of new energy utilization today.According to remote areas using electricity with the difficulty, this paperestablished the structure of a new household photovoltaic power system. Subjectmainly researched on the DC-DC converter, with a single set of independentMPPT control mode and battery charging control strategy to solve the problemof the efficiency of photovoltaic power generation which is reduced in shadowand the problem of short service life of battery. The main research contents areas follows:This paper introduced the principle of photovoltaic cells. Based on thecircuit model of photovoltaic cells, the simulation model of photovoltaic moduleis established, the output characteristic curve matching with actual curve. Thispaper expounds the influence factors of the maximum power point and theessence of the maximum power point tracking control algorithm. Simulation andcomparison of the three kinds control algorithm of MPPT, results show that theduty ratio perturbation method can quickly track the maximum power point. Theproblems of the MPPT technology put forward, the main content of this paper is determined.Analysis the output characteristics impact of PV modules in series, PVmodules in parallel and photovoltaic array in shadow. The output characteristicof centralized photovoltaic array is experimented in shadow. Results show thatshadow causes the problem of multiple extreme point appearance and the outputpower decrease in the power voltage curve. The more numbers of seriescomponents result in the bigger mismatch loss. The photovoltaic array structureand shadow type can cause the change of the output characteristics, leading tothe lower efficiency.The structure of the four kinds of photovoltaic power generation system isintroduced and analyzed the advantages and disadvantages in detail. Accordingto the design requirements of household photovoltaic power generation system,the structure of a new household photovoltaic power generation system isestablished, with a single set of independent MPPT control mode to solve theproblem of the lower efficiency of photovoltaic power generation in shadow.The hardware control circuits based on STM32F100C8T6has beendeveloped and debugged, which include several circuits such as MOSFETdriving circuit, sampling circuit, power supply circuit, battery prevented thereverse circuit. It is proved by experimental results that the designed circuits arestability and meeting the design requirementsSystem software architecture is planned on the designed hardware platform.With the modular design, in RealView MDK of software development platform,the software of timer interrupt service, A/D conversion, software filtering,maximum power point tracking control and battery charging control have beenwritten. Software is debugged on the designed hardware platform. It is verifiedby the debugging results that the software is feasible and stable running, whichcan able to finish the required function.The maximum power point tracking control and battery charging controlare carried out respectively on the experimental platform. The results show thatthe design of hardware and software is reasonable and feasible, which canfinish the design requirements. |
PDF Full Text Request