چكيده به لاتين
Due to the increase in energy demand and costs in recent years and the decrease in the price of photovoltaic systems, the possibility of connecting photovoltaic systems to the grid has increased. Grid-connected photovoltaic systems draw maximum power from the photovoltaic arrays and inject it into the grid. Most grid-connected systems are used to inject the power of photovoltaic arrays into the grid at a single power factor. Grid-connected photovoltaic systems in many countries of the world are installed in small units from one kilowatt to 5 kilowatts on the roofs of residential houses and in larger units as photovoltaic power plants. In order to design a microinverter connected to the network, various issues must be considered. These issues include circuit configuration, inverter efficiency, MPPT implementation, power quality and cost. The choice of circuit configuration depends on the input voltage and the number of processing steps. In the proposed microinverter, the power level for the simulation is 3.5kW single-phase, which is used in domestic and commercial applications. The ideal multi-stage micro-inverter (DC-AC-DC-AC) is proposed to provide all the desirable features of the mains connection system and load power supply. This microinverter has four main parts, high frequency all-phase phase shift, high frequency transformer, single-phase rectifier and single-frequency single-phase inverter (full frequency) (network frequency). In the first part, the dc voltage generated by the solar cells is converted to high frequency ac power by Full-Bridge, the topology of which is Full Bridge Phase-Shift, in this design using the parasitic elements of power switches. And the inductor added in the high frequency transformer path with ZVS technique reduces switching losses, increases switching frequency and also reduces the volume of transformers and inductors. In the second part, high frequency ac power passes through the high frequency transformer. In this stage, the transformer does two important things for us. Firstly, it transforms the transformer to the desired voltage level, and secondly, it creates isolation between the dc section and the ac section, and due to this separation, it increases the safety and reliability of the system. In the third part, the high frequency ac voltage produced with the desired voltage level is converted to dc by the rectifier. In this part, we use MOSFET to increase the efficiency of the system instead of using a diode in a diode, and also by designing a control circuit. Suitable for rectifiers The desired MOSFETs are also turned on by soft switching, which also reduces switching losses. Finally, in the fourth part of the generated dc power, it injects a 50 Hz ac voltage into the network and load by a low frequency single-phase inverter by means of unipolar modulation.
