A novel speed sensorless field-oriented control scheme of IM using extended kalman filter with load torque observer

The Extended kalman filter (EKF) has been found wide application in the sensorless control of induction motor (IM) because of its good steady and dynamic behaviour, disturbance resistance, and fast convergence. This paper presents a novel speed sensorless field-oriented control scheme of Induction motor using extended kalman filter. As the quadrature axes rotor flux is equal to zero in the field-oriented control, the observer based on the IM model in synchronous reference coordinate to estimate the flux and rotor speed simultaneously is simpler. Compared to the traditional observer using extended kalman filter, the orders of model and the matrixes are reduced, the complexity and the computational time are also decreased. The load torque is also observed by EKF and compensated to the system to reduce the ripple caused by a sudden change of the load torque. The speed and torque ripple in steady state also reduces when the load torque is included as a state variable. The simulation and experimental results show the validity and the feasibility of the presented scheme.