Study On Battery-Photovoltaic Charging System

Against the background of energy shortage and its pollution, solar energy as a new kind of energy is with large reserves, economic, cleanliness and so on. So, people begin to pay more attention to the use of solar energy. The paper designs a feasible solar energy charging controller and storage batteries are charged to meet the requirement from miniwatt appliance.A set of elementary solar energy charging system consists of solar cells, charging controller and batteries. The solar cells are basic and supply the energy for the system. The controller is the core of the system. And, based on the various states of solar cells and storage batteries, different control strategies are chosen and the storage batteries are also protected.The studying ways are the following:Firstly, the paper introduces the structural principle of solar cells. The solar cells, as a typical nonlinear element, use the photovoltaic effect to change solar energy into electric energy. The physical and mathematics models are showed and the analog simulation of about the solar panels'output under different solar intension and situations is also seen in this paper. At last, the nonlinear is verified.Secondly, the battery, as an energy storage device, is a most important part of the whole system. Thus, a lot of research work had been done to prolong the life-span of using the storage batteries. This paper analyses the basic structure and principle of the lithium batteries, and introduces the common battery charging method and the solar-cell--battery charging method.Finally, a sample circuit of solar-electric vehicle charging system is built, charging effect is availably. The paper designs a kind of charging controller based on pulse-width modulation technique. The controlling core is single-chip and the LM331 realizes to A/D switch (V/F). Then, ensuring the duty ratio is depend on the computing charge states of storage batteries. It is for ensuring the enough charging circuits in the early time and preventing from over-changing in the latter period. At last, the storage batteries can be protected. The experiment results show that the system can judge the statement of the charging mode and adopt the corresponding charging methods.