Sensorless speed control of permanent magnet motors with torque ripple minimization

A sensorless speed control strategy for permanent magnet AC machines with nonsinusoidal EMF waveform is presented in this paper. First, a nonlinear observer is proposed to estimate the EMF as well as rotor speed. Assuming that the EMF waveform is unknown, a high gain observer is proposed to estimate the time derivative of the position derivative of linked flux, which is needed for the EMF estimation. Then, the estimates are employed in the implementation of a torque control with minimum ripple. The performance of the proposal is validated through simulation.