| The simplest form of induction motors, known as AC squirrel cage motor, is the universal workhorse of industrial and commercial premises. For many years it was restricted to constant speed applications while DC motors were preferred for high-performance variable speed and servo drives. With modern advances in semiconductor and digital signal processing technologies, it is now possible to operate induction motors in high-performance drives at a reasonable cost with Field Oriented Control methods. The latter have made induction motor drives equivalent to DC drives in terms of independent control of flux and torque; and superior to them in terms of dynamic performance.;The first system is designed to estimate online the value of the slip gain in the entire torque-speed plane in order to maintain decoupled control of torque and flux despite the so-called detuning effects. It is based on evaluating the operating condition of the drive in terms frequency and load torque, and selecting the appropriate estimation method accordingly. A fuzzy controller is used to generate the distribution factor for the methods.;The second system is a fuzzy self-tuning speed controller, with reduced sensitivity to motor parameters and operating condition changes. It has the ability to adjust its gains in real time according to the current trend of the drive system. It is designed to maintain tight control of speed and torque for high-performance applications.;The performances of the two controllers are validated through a series of simulation and experimental tests using a 2HP 3-phase induction motor with an ADMC21992 160-MHz DSP microprocessor.;In developing Field Oriented Control for induction motors engineers are faced with two major challenges: (1) the estimation of rotor data to compute for the slip gain, and (2) the compensation of changes in drive operating conditions and parameters in order to maintain the drive performance high at all time. This thesis addresses these issues by introducing two independent control systems. |
