Field angle adaptation [induction motors]

In systems without converters for measuring the stator voltages, only reduced order observers based on the current equation are seen. Full order rotor flux observers are not applicable because stator voltage measurements are used. This problem is managed in this paper by an adaptive approach leading to a completely new method called field angle adaptation (FAA). The new contribution to the conventional current control system in rotor field oriented dq-coordinates is a signal added to the field angle in the transformation from rotor field coordinates to stator fixed coordinates. This signal adapts the field angle estimate to the correct rotor field angle in an induction motor