A systematic approach to selecting optimal flux references in induction motors

The problem of optimal selection of the flux reference in induction machines is addressed. The results are based on a standard differential equation model of the induction machine and give the value of the flux reference which maximizes the torque at constant speed given a bounded source voltage (optimal field weakening). Both the motor and the generator modes are considered. The formulae are useful for the real-time programming of digital controllers designed to achieve maximum performance of AC drives at high speeds. The optimal choice of flux reference is also calculated for the purpose of energy minimization and compared with torque maximization. The results are illustrated with numerical computations and simulations