Minimization of electric and magnetic losses in the speed control of induction motors

The article presents a minimization method of electric energy losses in rotor and stator windings and in the magnetic core of the motor during the frequency speed control of induction motors which limits the amplitude of the stator current. To solve this problem, the hybrid algorithm of parametric optimization, the mathematical model of the induction motor and the Pontryagin maximum principle are used. In the mathematical model of the motor both electromagnetic transients and the motor magnetic material saturation are taken into consideration. The electric energy losses in the magnetic core and in the windings of the motor are also calculated. An application example of the method developed for the idle starting of an induction motor is given.