الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Voltage source inverter (VSI) and current source inverter (CSI) are commonly the main power inverters utilized in various industrial applications. However, both have a drawback of limited voltage range operation. The growth of renewable energy sources as an alternative energy source has drawn the attention to improve power converters characterized with wide operating range with the capability of voltage bucking/boosting for maximum power point tracking and grid integration purposes. In addition, it must have the ability of power inversion from DC to AC and vice-versa to deliver and control the renewable harvested power to the grid. In order to add these features to conventional VSI and CSI, a dedicated stage of DC-DC converter must be implemented before the inversion stage. The inserted stage utilizes active and passive circuit components in order to buck/boost the input DC link of the inverter bridge. This type of converters is widely known as two stage converters and can be categorized according to the usage of high frequency transformers into two main types: • Isolated two stage converters. • Non-isolated two stage converters Regardless of the remarkable robust performance of the two stage converters, adding an extra stage with extra active and passive components increases system complexity, losses, cost and footprint size. Consequently, single stage buck/boost inverters were introduced, offering better features compared to two-stage converters. Impedance source inverter (ZSI) was introduced as a single stage converter with the ability of voltage bucking/boosting and inversion without introducing any extra active switches to the main topology of VSI and with relatively simpler control strategies and implementations. Nevertheless, ZSI has drawbacks of high voltage stresses on the utilized power electronic devices, sharp non-linear voltage gain variation and large size impedance network, which creates a research gap that initiates attempts to improve ZSIs’ performance by proposing new to pologies based on the basic X-shaped ZSI topology or by introducing new pulse width modulation techniques. This thesis focuses on the main improvements of ZSIs’ topology and pulse width modulation (PWM) techniques. A MATLAB/SIMULINK® simulation comparative study is carried out for various PWM techniques of three-phase ZSI. A proposed modified discontinuous PWM (MDCPWM) technique is introduced as a contribution to the research in order to achieve better performance for three-phase ZSI. The proposed approach is experimentally validated using a laboratory prototype in addition to rigorous simulation study.