Diseño e implementación de un sistema de conversión y de un prototipo de carga mediante energía solar fotovoltaica de baja potencia

Abstract

Currently the alternative energies are profiled with a solution to the continuing rise of fossil fuels and global warming; this is why today the generation of electricity from energy sources such as solar, wind, geothermal and others, are of great importance to study in the international scientific community. Additionally, the generation of electricity in inaccessible areas using alternative energy is a choice that takes strength in recent decades because of the cost of building distribution systems of electricity. In this thesis we propose the design and implementation of a conversion system and a prototype charge through low power solar energy. For this we carry into effect a study of the state of the art in relation to different types of existing power converters existing in the market. The designed system includes the steps of battery charge, boost converter and DC-AC converter for which the first one is used a reducer Buck type converter synchronous for load management activities to deep cycle batteries. Among the activities to be performed by this buck converter are primarily to search the maximum power point of the photovoltaic panels in order to extract the maximum power available from solar radiation and a constant voltage charge which limits the current injection to reach the float voltage determined by the manufacturer. The implemented charger reaches an energy efficiency of 87 % at nominal power and the control system implemented in the charger allows to easily modify the parameters of interest depending on the type of battery used in the application. For the second stage, the designed system raises the nominal battery voltage and then converts it into alternative energy; an isolated Push-Pull converter has been used with a converter transformer center tap in the primary winding and a single secondary winding followed by an uncontrolled rectifier bridge, this switched by effect transistors MOSFET field managed by a dedicated control circuit with voltage feedback and currents which guarantee the protection against overloads. This converter reached an experimental performance above 75%, typical yield for this topology, mainly copper losses in the transformer core. Finally in the line of power management it was designed an inverter with full bridge topology H using the zero crossing distortion square modulation obtaining an approximate 30% distortion in the charging voltage.