Nonlinear control of induction motors: the observed field oriented control scheme

In this paper, we modify the standard field-oriented control (FOG) transformations to facilitate the design of an adaptive observed field-oriented control (OFOC) scheme which is free of singularities, does not require rotor flux measurements, and provides for simultaneous rotor flux tracking/rotor position tracking. Specifically, given measurements of rotor position, rotor velocity, and stator current, the controller ensures global asymptotic rotor position/rotor flux tracking despite the uncertainty associated with the mechanical subsystem parameters and the stator circuit electrical parameters.