The universal field oriented controller

The synthesis of a universal field-oriented (UFO) controller is presented. The UFO is capable of decoupling flux and torque in an arbitrary reference frame. Due to its high degree of generality, it is fully compatible with all existing field-oriented controllers, indirect as well as direct. As a consequence, the digital integration of the UFO scheme in all induction motor drives with the same hardware and software is feasible. Examples are worked out using a high-speed digital signal processor. It is noted that in certain operating conditions the flexibility of changing the flux reference frame can extend the stability region or the torque capability curves of the drive. Detuning problems in field orientation are handled in an optimal manner for each field-oriented controller by proper selection of the model of the induction machine and its reference frame.<>