Steady-state optimization of induction motor drives operating in the field weakening region

The steady-state performance optimization of vector-controlled induction motor drives operating in the field-weakening region above base speed is discussed. Three indirect vector control schemes, stator flux field-orientation control (SFOC), rotor flux field-orientation control (RFOC), and airgap flux field orientation control (AFOC), are considered for maximum torque and maximum motor efficiency operation. The optimization of a weighted function comprising the torque and efficiency is also considered. The three field orientation schemes give the same maximum torque while the RFOC has the best optimal efficiency