A novel DSP based speed sensorless performance evaluation tool for induction motors

This paper proposes a new DSP based tool for evaluating the performance of induction motors. The approach is based on the acceleration method presented in the IEEE Std. 112. The motor´s torque is calculated using two line currents and voltages. An algorithm to track the speed related saliency induced harmonics from the machine´s line current spectrogram is presented. The use of linear and quadratic time-frequency representations is investigated as a viable solution to the task at hand. The difficulties encountered, including a limited dynamic range and the presence of cross terms, are addressed and the suggested solution is provided. The complete algorithm will then be used to obtain the induction motor´s performance curves. Experimental results corroborating the proposed algorithm are presented, and a discussion of the advantages and disadvantages of such an approach is touched. The implementation of the algorithm on the TMS320C24x family of DSP chips is also discussed. The technique is proposed to be part of a complete stand-alone panel mounted induction motor diagnostic tool currently being developed in our lab.