| Summary: | 碩士 === 國立高雄應用科技大學 === 模具工程系碩士班 === 102 === Due to climate warming and environmental issues, the development of renewable energy has become the current trend. But the weather changes enormously, the irradi-ance of sun could be variable at any time and the output power of the renewable energy will be unstable. Therefore, the maximum power point of solar cell will be dependent on the time of year, time of day, and the latitude of the photovoltaic system. The purpose of this study is to develop a DC to DC converter with maximum power point tracking for commercial 245 W and 85 W photovoltaic modules. It can also track the maximum power point of photovoltaic modules with partial shading.
In the study, the main model of DC to DC converters is built up by using the PSpice. The model are also combined the maximum power point tracking algorithms with Perturb and Observe Method (P&O) and Incremental Conductance Method (I.C.). These effects of the different tracking methods, variation of irradiance, different rating of modules and distinct topology of converters are compared in this research. The sim-ulation can study the maximum power point tracking condition directly using the PSpice environment, without the use of additional software else. With the developed models, three topologies of converter: buck converter, boost converter and Single-Ended Primary-Inductor Converter (SEPIC) are established to simulate the performance of the MPPTs.
It is disclosed that both of boost converter and SEPIC converter have the best effi-ciency when using the algorithm of P&O. The boost converter has 94% efficiency at output power 245 W, but reduced to 83% at output power 85 W because of the transient time longer. The SEPIC converter has 95% efficiency at output power 245 W, but also reduced to 85% at output power 85 W. In addition, both of the buck converter and SEPIC converter have the best efficiency when using the algorithm of I.C. The buck converter efficiency can up to 95% at output power 245 W, but reduced to 78% at out-put power 85 W due to the transient time longer. The SEPIC converter has 94% effi-ciency at output power 245 W, and dropped to 83% at output power 85W. Finally, a 85 W buck converter with P&O MPPT algorithm was made and tested for comparing the simulation models. For the experimental test, the efficiency can up to 76% at output power 72 W and up to 85% at output power 40 W. It is also disclosed that the waveform is similar as the simulation results. Therefore, it can make sure that the technological feasibility of maximum power point tracking system built in the PSpice software.
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