Proposed torque optimized behavior for digital speed control of induction motors

In this paper. a control strategy for speed control of induction motors with field orientation is proposed. The proposed method adjusts the output voltage and frequency of the converter to operate the motor at the desired speed with maximum torque per ampere at all load torques keeping the torque angle equal to 90degrees. A comparison between the performance characteristics of a 2 lip induction motor using three methods of speed control is presented. These methods are the proposed method. the direct torque control method and the constant V/f method. The comparison showed that better performance characteristics are obtained using the proposed speed control strategy. A computer program, based on this method, is developed. Starting from the motor parameters, the program calculates a data set for the stator voltage and frequency required to obtaining maximum torque per ampere at any, motor speed and load torque. This data set can be used by the digital speed control system of induction motors. (C) 2002 Published by Elsevier Science Ltd.