Optimal field-weakening algorithm for direct torque control of sensorless traction drive with induction motor

This paper deals with the field-weakening of the traction induction motor drive. The field-weakening method is optimal with respect to the voltage and current limits. The drive is controlled using the Direct Torque Control method with the Space Vector Modulation algorithm, DTC-SVM. The speed of the drive, used in the system, is estimated using two estimators, both are the Model Reference Adaptive System (MRAS) type. One of them takes the advantage of the PI controller, the second one uses the sign function, what is typical for the Sliding-Mode theory. The described issues are illustrated using experimental tests results, obtained on a laboratory setup with 50 kW induction motor