Speed and position sensorless permanent magnet synchronous motor drives

An indirect rotor speed and position sensing technique based on computation for a permanent magnet synchronous motor (PMSM) drive is presented in this paper. New expressions in terms of stator variables for rotor speed and position angle are derived and computed using real data from a laboratory prototype PM motor. The results show that the rotor speed and angle are in close agreement with those obtained from an electro-mechanical sensor. A two-loop PMSM drive system is then simulated using the derived expressions