Fuzzy supervisory control of field oriented controlled AC drives

The problem of setting an optimum flux reference for indirect vector controlled induction motors is addressed. The flux reference is generated using a fuzzy logic supervisor (FLS) which minimizes the power input to the motor in steady-state speed operations. The FLS is based on a simple search method. However, it does not operate when the speed reference is changed, in order to keep the decoupling of the speed and flux loops obtained by vector control; and it takes into account the possible operation of the motor in the field-weakening region for speed higher than rated. The structure of the FLS makes it insensible to load torque variations, magnetic saturation and inverter voltage limitations. Simulation results show the satisfactory performance of the FLS in a wide speed range and the sensible improvement in motor power consumption, in a practical industrial application.