Nonlinear optimal control for Synchronous Reluctance Machines

Abstract

A nonlinear H-infinity (optimal) control approach is proposed for the problem of control of Synchronous Reluctance Machines (SRMs). Approximate linearization is applied to the dynamic model of the Synchronous Reluctance Machine, round a local operating point. To accomplish this linearization Taylor series expansion and the computation of the associated Jacobian matrices are performed. The robustness of the control scheme assures that the modelling error due to truncation of higher order terms from the Taylor expansion will be compensated. Next, an H-infinity feedback controller is designed. After solving an algebraic Riccati equation at each iteration of the control algorithm, the feedback gain is computed. Lyapunov stability analysis proves that the control loop satisfies an H-infinity tracking performance criterion. This in turn signifies elevated robustness to model uncertainty and external perturbations. Moreover, under moderate conditions it is proven that the control loop is globally asymptotically stable.