STABILITY AND PERFORMANCE ANALYSIS OF A VARIABLE SPEED CONTROLLED SLIP INDUCTION MOTOR DRIVE

Abstract

This dissertation concerns an induction-motor drive fed from a rectifier-controlled current inverter source. The u se of a speed regulator, p-i current regul ator and slip-speed regulator makes this drive a closed-loop system. The work in the beginning discusses the steady-state performance of the drive. Effect of variation in load torque on the drive power output, induction-motor stator voltages and power factor, and drive efficiency at different p.u. operating frequencies are discussed. Induction-motor fed from rectifier-controlled-current-inverter source exhibit instability in open-loop mode of operation in unstable zone of torque-speed characteris-tic. However, this is the only region where the drive can be operated without causing saturation in the induction-motor. As such speed regulator, a p-i current regulator and a slip-speed regulator are used to stabilize the drive. The system characteristic equation is developed by employing the theory of shall displacement and the D-partitioning technique is applied for parameter coordination which ensure stable opera-tion of the drive over very wide range of speed variation with a prescribed degree of stability.