Design and Implementation of a Boost-Power-Stage Converter for Photovoltaic Application
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Photovoltaic generator is a device that converts solar radiation originated from the Sun into electrical energy. Power electronics are used to feed this electrical energy into the grid. In the design of a converter that is connected to the photovoltaic generator, it is important to know the maximum values of the generator output: Maximum output power, short-circuit current and open-circuit voltage, which are dependent on the amount of incident radiation and the value of ambient temperature. Maximum value for short-circuit current and open-circuit voltage were found based on the year-round irradiation and temperature measurement data. In this thesis, two boost-power-stage converters were designed. Design of the first converter was based on the conventional method that was introduced in the literature. In that method, the inductor and semiconductors were sized by using current that was derived by dividing input power of the converter by input voltage. Value of the converter input power was calculated by multiplying the standard test condition output power of the selected photovoltaic generator by conventional sizing factor, which is the ratio of the converter nominal input power to the nominal output power of the photovoltaic generator. The second converter was designed by using the information about the real maximum output current of the selected photovoltaic generator, which is the short-circuit current. The converters were designed in such a way that both have the same amount of switching frequency input voltage ripple and equal ability to prevent the low frequency output voltage ripple from affecting the input voltage. Even if the converters are electrically similar, the conventional design method leads to higher input capacitance, larger inductor core size and more uneven temperature distribution of the power semiconductors at the maximum power point than the new design method. Thus, the conventional design method leads to unnecessary oversizing. Significant cost savings can be achieved by applying the new design method, which is presented in this thesis for the first time. The results were verified by experimental measurements.