The paper presents the design of an induction motor speed estimator based on rotor slot harmonics with the focus placed on analyzing its integration within the current and speed control loops. The shaft speed is estimated based on the stator current spectrum. The estimator’s output is used as a feedback signal for the speed and vector control. The experimental results demonstrate the speed and vector sensorless closed-loop operation on three-phase 2.2kW induction motor, with 5 Hz speed closed-loop bandwidth, in a wide spreed range of the motor, including very low speeds.
