Double fed induction machine drive: proposal of a speed sensorless control based on a MRAS

A criterion to estimate the speed in a double fed induction machine is proposed. It is based on a MRAS; as an innovation, the rotor flux from the reference model is introduced in the adjustable model, pre-multiplied by a scalar constant g. It allows to obtain a transfer function between the estimated and the real speed, where the integral term of the controller is not cancelled and the closed loop does not exhibit a steady state error. A method to choose the parameter g is also described. A computer simulation and an experimental test validate the proposed method