Extended mechanical observer structure with load torque estimation for sensorless dynamic control of permanent magnet synchronous machines

The paper describes an extended mechanical observer structure in combination with an enhanced voltage model for sensorless control of permanent magnet synchronous machines (PMSM) in the whole speed range. The observer estimates rotor speed, rotor angular position and load torque. An occurring deviation of both components; the estimated rotor position and the estimated speed, is fed back to the voltage model. Thus, a stable operation with high robustness against parameter uncertainties is obtained. The third component, the estimated load torque, gives information to the current controller, so the speed controller can be implemented as a simple proportional element.