A speed estimator for sensorless vector control of induction machines in the field weakening region

A number of speed estimation schemes for sensorless vector control of induction machines utilise a mathematical model of the machine in the estimation process. Operation of a sensorless indirect rotor flux oriented machine in the field weakening region requires that the variable degree of main flux saturation is recognised and compensated in the speed estimator. The paper describes implementation of a proposed modified version of the rotor flux based MRAC type of speed estimator, that fully compensates for the variable degree of main flux saturation. Effectiveness and accuracy of the developed sensorless vector control scheme for operation in the field weakening region are verified by experimentation