Induction Motor Drive using Reduced Switch Multilevel Inverter

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 har