A transputer-based speed identifier for induction motor drives using real-time adaptive filtering

A novel sensorless speed identifier for induction motor drives is proposed. It is based on the real-time calculation of rotor slot harmonics (RSHs) using an adaptive digital filter. It outperforms any other analogue or spectrum-based speed identifier in terms of accuracy and speed of response. The new identifier measures the speed, by processing two stator currents, with an accuracy better than 0.1% on a sample-by-sample basis. It is also capable of tracking speed transients, of high slew rates, with similar accuracy. This is notable as the first effective tracking of RSHs during transients ever reported. The proposed algorithm is computationally very efficient, and requires only a single processor for its real-time implementation. Simulated and experimental data were used to validate the algorithm.