Extended Kalman filter for speed sensor-less DTC based on DSP

The Kalman filter is a special kind of observer, which provides optimal filtering of the noises in measurement and inside the system if the covariance matrices of these noises are known. Extended Kalman filter (EKF) for speed sensor-less direct torque control (DTC) of induction motor drive system is presented in the paper. EKF is used to estimate stator flux and rotor speed for DTC, especially in low-speed condition. Besides, the real time implementation method of the control strategy based on fixed pointed digital signal processor (DSP) TMS320F240 is also given. Simulation and experimental results confirm the validity of the proposed estimation technique.