An applicaton of the extented Kalman filter in servo motors of medical equipments

Servo motors have been widely used in medical equipment, but servo motors have the large torque and flux linkage ripple in the conventional direct torque control (DTC). The stator flux linkage estimation in the conventional DTC also needs the integration of the back electromotive force (back-emf), and is largely affected by the value of the stator resistance. The application of the extended Kalman filter (EKF) in the aspect of estimating stator flux linkage is studied in this paper, reducing the torque and flux linkage ripple and eliminating the integration of the back-emf. The simulation results indicate that the proposed method not only does well in the speed, the rotor position and the stator flux linkage estimation, but also is robust to the stator resistance.