Speed and rotor flux estimation of induction motors based on extended kalman filter

Two problems must be solved in the speed sensorless vector control of induction motor drive: the speed estimation and rotor flux observation. Because of the multiplication terms of state variables, the induction motor model is the non-linear state equations. To estimate the state variables of motor model and gain the rotor flux and speed signals, the paper proposes a method to estimate them using extended Kalman filter. Experiment is based on the DSP design system for digital motor control. Software programs carry out extended Kalman filter algorithm to estimate the rotor speed and fluxes. The satisfied experimental results prove that extended Kalman filter algorithm can real time estimate rotor speed and flux very accurately, and based on which the speed sensorless drive system has good static and dynamic performance.