الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The output voltage of the square wave inverters is rich of harmonics. These harmonics have negative effects on the source and the load. To overcome their negative effect, many researches have worked on eliminating and/or reducing the harmonic content in the inverter output voltage.
In this thesis, Selective Harmonic Elimination (SHE) pulse width modulation (PWM) technique is used to produce a predefined switching pattern at the inverter output voltage. This pattern is determined by solving a set of nonlinear equations using Genetic algorithm optimization technique in order to eliminate specific lower-order harmonics.
The performance of single-phase SHE-PWM inverter with unipolar and bipolar switching patterns has been investigated. To further improve the quality of the load voltage and obtain a nearly perfect sinusoidal voltage, a second-order low-pass filter is employed at the inverter output.
The performance of an open-loop, single-phase inverter with a second-order low-pass filter and feeding a resistive and R-L loads is investigated through both simulation and experimental results. It is shown that, using the proposed SHE-PWM technique, a high quality inverter with nearly perfect sinusoidal load voltage is achieved. The Total Harmonic Distortion (THD) of the load voltage is measured to be 4.5% at a reasonable switching frequency of 1450 Hz and small size filter.
In order to account for load dynamics and maintain a well regulated load voltage, a multi-loop feedback control is employed. The control scheme comprises of inner capacitor current and outer load voltage feedback loops. A Proportional-Resonant (PR) controller is employed in the feed-forward path of the inner feedback loop for
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the load voltage to faithfully track its reference signal with very low steady-state error.
Finally, speed control of three-phase induction motor (IM) using the constant V/f control is investigated using the proposed SHE-PWM technique. It is shown that the proposed SHE-PWM technique provides a low cost method for speed control of three-phase IM.