الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Photovoltaic (PV) power sources are gaining more attention due to lack of energy generated from conventional sources and the increasing concern about global warming. Accordingly, a large number of researchers turn their attention to power inverter circuits which act as an interface between PV sources and utility grid. These power inverters have been used in a wide variety of industrial applications, such as distributed power generators, uninterruptible power supplies and adjustable speed drive systems. Conventional voltage source inverters (VSIs) are generally buck DC-AC power conversion, where the DC source voltage is higher than the peak AC output voltage. Furthermore, For PV applications, an additional DC-DC boost converter is required as preliminary stage before the VSI to obtain a high DC-DC gain. This configuration is normally called two-stage DC-DC-AC power conversion and suffers from several drawbacks such as less efficiency, lower reliability, large size and high cost. Due to the necessity of increasing inverter efficiency and reducing overall cost, encouraged research work to develop single stage topologies that combine the performance of the two-stage topologies is the current trend of researchers objective, as they are more reliable and have lower component which increases the system power density. During the last few years, a lot of single –stage topologies are presented, such as the three-phase Z-source inverter (ZSI), the quasi-ZSI, switched-boost inverter (SBI), and quasi-switched boost inverters (QSBIs). Although they have a lot of advantages such as low input current ripples, overall voltage gain, continuity of the input current, and conversion efficiency. They suffer from the high component count, which increase the size, weight and cost of the power inverter. This thesis proposes a topology for a high efficiency single-stage single-Phase boost inverter with a simple circuit configuration and a low component count. Only four switches and one inductance are used in the proposed inverter. As a result, it offers the advantages of reduced cost, size, and weight. The proposed inverter produces instantaneous output voltages higher than the input DC voltage without an intermediate power conversion stage. A new control scheme is designed that enables the proposed inverter topology to produce a high performance , low distortion sinusoidal output waveforms and provide good load voltage regulation . The thesis also introduce a single-stage three-phase boost inverter. Only six switches are used in the proposed inverter. Reduced cost, size, weight, and complexity of the control circuit are the main advantages of the proposed inverter. The proposed circuit topology uses only one inductance on its configuration, that improve the overall circuit performance. A new control methodology is proposed to provide regulated AC output voltage and current closely to sinusoidal waveform, and it is capable of being applied to both grid-connected and stand-alone cases. As the photovoltaic generators have a nonlinear characteristics and different maximum power points which vary with the illumination level and temperature, this thesis proposes a method to track the maximum power point (MPPT) using a new technique of MPPT called voltage based method. The proposed method of MPPT has the advantage that, no loss in power delivered to the load, and decrease the sensors used that decrease the system cost and increase its reliability. The proposed inverter topologies are described and simulated using Matlab /Simulink under different cases. Also the topologies are verified experimentally by building a laboratory model using the digital signal processor (Model DS1104). The simulation and experimental results show that the proposed inverter topologies produce output AC voltages higher than the input voltage with low components used, that increase the reliability of the proposed inverters. Moreover, the proposed inverters are subjected to different conditions such as, an increase in load and a step change in reference voltage, and the obtained results verify the effectiveness and high performance of the proposed control algorithm. Also the results approve that the proposed new control methodology has the ability to achieve the desired even if the proposed topologies are supplied from DC source or supplied from PV source.