Speed estimation for induction machines using imaginary power

This paper presents a novel algorithm for sensorless speed estimation for induction machines. The algorithm uses the instantaneous imaginary power flowing into the machine as the basis of the estimation technique. The algorithm is simple and requires minimal parameter knowledge. Furthermore, being based on imaginary power, it does not suffer from accuracy problems at low speeds due to the influence of stator resistance. The paper outlines the algorithm and then presents simulation and experimental results on an induction machine drive system.