Robust observer with higher-order sliding mode for sensorless speed estimation of a PMSM

This paper addresses the problem of sensorless speed estimation for the permanent magnet synchronous motor (PMSM). A higher-order sliding mode (HSM) observer is developed to provide estimation of back electro motive forces (EMFs) that are treated as unknown inputs without the use of lowpass filter. A finite-time smooth estimation is obtained and the chattering phenomenon is eliminated. An accurate speed estimate of PMSM can be algebraically computed with the estimated back EMFs. Experimental results show the effectiveness of the proposed method.