Speed sensorless direct torque control of induction motors using an adaptive flux observer

The authors present a new sensorless induction motor drive. The drive uses an adaptive flux observer for speed estimation and the discrete-time direct torque control technique for torque and stator flux control. The adaptive flux observer uses a mechanical model to improve the behavior during speed transients. The estimated stator flux of the adaptive observer is used in the discrete-time direct torque control method to provide fast torque response combined with torque ripple free operation over the whole speed range. The sensorless drive system is capable of working from very low speed to high speed and exhibits good dynamic and steady state performance. The authors demonstrate the steady state and dynamic performance of the proposed sensorless drive using simulation and experimental results