Super-twisting control of induction motors with core loss

A novel nonlinear affine model for the induction motor with core loss is developed in the well known (α, β) stationary reference frame. The core is represented with a resistance in paralled with the magnetization inductance. Then, an optimal rotor flux modulus is calculated such that, the power loss due to stator, rotor and core resistances is minimized, and as a consequence the motor efficiency is raised. The calculated optimal flux modulus is forced to be tracked by the induction motor along with a desired rotor velocity by means of a super-twisting sliding mode controller. Using a novel Lyapunov function, the closed-loop stability of the system is demonstrated. A simulation study is carried on, where the superior performance of the proposed controller is put in evidence when compared to the same controller when not taking into account an optimal flux modulus.