A novel speed sensorless technique for obtaining the speed-torque characteristics of induction motors for commissioning

This paper proposes a new approach for obtaining the induction motor speed-torque curve. The approach is based on the acceleration method presented in the IEEE Std. 112. The motor starting torque is calculated using two line currents and voltages. An algorithm to track the speed related saliency induced harmonics from the machine line current spectrogram is presented. The difficulties encountered using such an approach are addressed and the suggested solution is provided. The complete algorithm is then used to obtain the induction motor speed-torque curve at the steady state. Experimental results corroborating the proposed algorithm are presented, and a discussion of the advantages and disadvantages of such an approach is given.