application of speed estimation techniques for induction motor drives in electric traction industries and vehicles

induction motors are the most commonly used in the traction industries and electric vehicles, due to their low primary cost, low maintenance costs, and good performance. speed identification is needed for the induction motor drives. however, using of speed sensors in the induction motor drives is associated with problems such as, extra cost, reduced reliability, added mounting space, etc.. therefore, many of the recent researches had been dedicated to sensor less induction motor drives. in the induction motor, the rotor speed is estimated using measured stator voltages and currents of the induction motor, as the sensor less drive. the rotor speed for sensor less induction motor drives can be estimated by various techniques, which is designed with respect to required accuracy and sensitivity against induction motor parameter variation. in this paper, comprehensive review of different induction motor speed estimation techniques for traction applications, their special features and advantages is presented.