Sensorless nonlinear control of permanent magnet synchronous motors

This paper introduces a nonlinear control scheme based on exact feedback linearization to control the speed of a permanent magnet synchronous motor (PMSM). Since the nonlinear controller needs all the states of the motor, the authors use a reduced order observer to estimate rotor position and speed, avoiding the use of mechanical sensors to build the control strategy. Exact linearization achieves a linear input/output model that is fed back in order to have a speed loop with a PI controller. The stability of the closed loop system is proved through a singular perturbation argument and the system performance is tested by simulation