Sensorlees Speed Estimation. A Review

In induction motors diagnosis, sensorless speed estimation has become a key factor when it comes to locate fault harmonics. Yet, there are some issues that have not been solved. First, since methods were mainly thought to control purposes, they are intended to provide real time response, which means short data records. In FFT techniques (widely used in fault diagnosis) those short data records mean low accuracy. Second, most methods require specific machine parameters that are neither available, nor easily estimated. The present paper is a state of the art review on sensorless speed estimation. It is intended to be a guide for industrial professionals where they may find which method fits better their problems. Moreover, it also analyzes and points out the current problems of using sensorless speed estimation in fault diagnosis to indicate future lines of research where academia could focus their efforts to finish solving the problem.