Sliding mode observer with its salient features is considered one of the robust observers for flux and
speed estimation of sensorless induction motor drives. However, the discontinuous switching function
of the sliding mode observer causes a significant chattering which is considered a serious drawback. In
this paper, a modified robust chatter-free sliding mode observer for sensorless induction motor drives is
presented. The discontinuous switching hnction is replaced by a continuous one to eliminate chattering.
The accuracy and robustness of the proposed sliding mode observer are examined at motor starting and
load torque variations. A floating-point Digital Signal Processor (DSP) TMS320C31 control board with
a hardwarelsoflware interface is used to implement the proposed sliding mode observer for speed
estimation. Simulation and experimental results are presented and discussed