Robust output feedback linearizing speed sensorless control of PMSM

This work addresses the problem of robust output feedback speed sensorless control of a three-phase permanent magnet synchronous motor (PMSM). A cascaded observer scheme is proposed comprising a continuous sliding mode observer (SMO) and an extended high-gain observer (EHGO) that provides robust estimation of motor position, speed and lumped system uncertainties. For the speed control problem, a robust feedback linearization controller is presented that uses the estimated lumped disturbance provided by EHGO to actively compensate for uncertainties. This observer based scheme helps to recover the motor speed tracking performance achievable under exact feedback linearization. The overall scheme works in output feedback; that is, without speed sensor, requiring motor current as the only output measurement. Simulations and experiments confirm the efficacy of the proposed scheme.