Adaptive-speed identification scheme for a vector-controlled speed sensorless inverter-induction motor drive

The authors describe a model reference adaptive control system for speed control of the vector-controlled inverter induction motor drive without a speed sensor. The rotor speed is estimated with a full-order adaptive observer and is used as the feedback signal for the vector and speed controls. In order to estimate the speed accurately at low speeds, the motor stator resistance is also identified at the same time to correct the mismatched resistance value used in the observer. The resulting system is verified to be hyperstable. As a result, the drive can be operated in a wide range of speed, and especially, it can be operated stably at the state of zero speed. Experiments also show that the scheme is effective