Research On Photovoltaic Power System Based On MPPT

Solar power is a new green power. It is regarded as clean, pollution-free, and inexhaustible. Photovoltaic conversion is an effective way to use solar power. Because the price of photovoltaic cell is expensive and conversion efficiency is low presently, the Maximum Power Point Tracking (MPPT) is absolutely necessary, in order to decrease system cost and increase efficiency,The paper focuses on the stand-alone photovoltaic system and analyzes it with theory. We pay our emphases on the implementation about selecting parameters, topology structure, control strategy, MPPT, maintenance of storage battery, and so on. The main contents are listed as follows:1. An overview on developing photovoltaic system is discussed presently.2. The conventional structure and MPPT structure of photovoltaic generation system are introduced respectively. The MPPT inevitability is analyzed with the output characteristic of photovoltaic cell.3. The principle and characteristic of some DC-DC conversion circuits are introduced in this paper.4. Sampling and regulating circuits of the photovoltaic array output current and voltage, DC-DC conversion circuit with MPPT are designed. Drive circuits are realized based on M57962L.5. Adopting perturbation and observation method, MPPT control software based on dsPIC30F4011 is designed.6. The charging and discharging electrochemistry mechanism of the storage battery is mentioned. MPPT control is active in charging. Because charging and discharging of storage battery are controlled effectively, the phenomenon of over charging and discharging are avoided in operation.Finally, the proposed control methods are proved practicabl by the results of experiments.