SENSORLESS FIELD ORIENTATION CONTROL OF INDUCTION MACHINES BASED ON AMUTUAL MRAS SCHEME

A mutual model reference adaptive system (MRAS) is proposed to impleme nt a position sensorless field-orientation control (FOC) of an inducti on machine. The reference model and adjustable model used in the mutua l MRAS scheme are interchangeable. Therefore, it can be used to identi fy both rotor speed and the stator resistance of an induction machine. For the rotor speed estimation, one model is used as a reference mode l and another is the adjustable model. Pure integration and stator lea kage inductance are removed from the reference model, resulting in rob ust performance in low and high speed ranges. For the stator resistanc e identification, the two models switch their roles. To further improv e estimation accuracy of the rotor speed and stator resistance, a simp le on-line rotor time constant identification is included. Computer si mulations and experimental results are given to show its effectiveness .