الفهرس 
INTRODUCTION 1Only 14 pages are availabe for public view
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Abstract
Induction motor typically rotates with un-controllable speed; the
speed fluctuates with load variation. In order to satisfy the required
development in various industries, it is targeted to get a motor of
controllable speed, fast and stable dynamic response. Here comes the need
for motor drives, which are capable to control the motor speed or torque
within certain dynamic response limits. Hence, induction motor drives
represent an essential interest for the academic research and engineering
industries. Currently, the latest researches aim to enhance the performance
of the induction motor drives especially for applications demanding
precise control of speed or torque like laser cutting, welding and polishing
industries. Also these researches target to reduce the harmonics injected
by the induction motor drives through applying novel control techniques
and utilizing multilevel inverters.
Basically, the induction motor drives performance is determined
based on two essential concepts; the utilized inverter and the applied
control principle. For the utilized inverter, the thesis proposes a modified
cascaded thirteen-level multilevel inverter topology and an improved
modulation technique. where the proposed multilevel inverter topology
accompanied by the improved modulation technique grants a multilevel
inverter of compact size, simple control, and staircase sinusoidal output
waveform with reduced harmonic distortion content. For the control
principle, the thesis applies the vector control principle, Direct Torque
control specifically. Since the direct torque control methodology offers an
enhanced dynamic response performance. Hence, the combination
between the proposed multilevel inverter and direct torque control leads to
an induction motor drive of fast dynamic response and less harmonic
distortion content.
The thesis presents detailed simulations to validate the
performance and features of the proposed cascaded thirteen-level
multilevel inverter configuration, modulation technique, and motor drive.
The results show that the proposed multilevel inverter along with the
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modified modulation technique succeeds to reduce the total harmonic
distortion. Also, this proposed multilevel inverter enhances the dynamic
performance of induction motor drive and limits its injected harmonics.
These simulations are presented through MATLAB/Simulink environment
software.