Research on the Fuzzy-Control based Maximum Power Point Tracking Technology for Photovoltaic System

• Main Authors: Chun-Liang Liu, 劉俊良
• Other Authors: Yi-Hua Liu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/md4x7t

碩士 === 國立臺灣科技大學 === 電機工程系 === 99 === The ever-increasing demand for low-cost energy and growing concern about environmental issues has generated huge interest in the utilization of alternative energy sources such as the solar energy. A photovoltaic cell (PV cell) is a specialized semiconductor diode and can be utilized to convert the freely and abundantly available solar energy into electrical energy. One of the major advantages of PV cell is the fact that it is non-polluting, requiring only real estate in order to function. Another advantage is the fact that solar energy is unlimited. Once a photovoltaic system has been installed, it can provide energy at essentially no cost for years, and with minimal maintenance. A major challenge for using the PV cell is that its I–V characteristics is nonlinear, which result in a unique maximum power point (MPP) on its P–V curve. This matter is further complicated due to the dependence of these characteristics on solar irradiation and temperature. Therefore, a maximum power point tracking (MPPT) technology is essential for PV system. In this thesis, a fuzzy-control based MPPT algorithm is proposed. By using the deviation of power (△P) and the deviation of voltage (△V) as the fuzzy controller input，the required control variable (duty cycle) can be deduced. In this thesis, the power stage of the PV system is the boost converter and the firmware is implemented using the dsPIC digital signal controller (DSC) from Microchip. In order to validate the correctness of the proposed algorithm, a graphical user interface (GUI) is also presented to monitor and record the operating status of the proposed PV system. According to the experimental results, the proposed system can improve the tracking speed and the steady state performance of the MPPT comparing to conventional fixed-step perturb and observe (P&O) method.