Nonlinear Optimal Control of Magnetically Geared Induction Motors

The present article proposes a non-linear optimal control method for magnetically geared induction motors (MGIMs). It is proven that the dynamic model of the magnetically geared three-phase induction motor is differentially flat, which confirms the controllability of this system. Next, to apply the non-linear optimal control scheme, the dynamic model of the magnetically geared motor undergoes approximate linearisation with the use of a first-order Taylor-series expansion and through the computation of the associated Jacobian matrices. For the approximately linearised model of the MGIM, an H-infinity optimal feedback controller is designed. To compute the controller’s stabilizing feedback gains, an algebraic Riccati equation has to be solved repetitively at each time-step of the control algorithm. The global stability properties of the non-linear optimal control scheme are proven through Lyapunov analysis.