George Papafotiou, Automatic Control Laboratory Swiss Federal Institute of Technology

Abstract: From the control point of view, power electronics systems constitute excellent examples of hybrid systems, since the discrete switch positions are associated with different modes of continuous time dynamics. The recent theoretical advances in the field of hybrid systems, together with the latest technology developments that have made available significant computational power for the control loops of power electronics systems, are inviting one to revisit the control issues associated with power electronics applications. In this talk, we demonstrate the application of hybrid optimal control methodologies to power electronics systems. More specifically, we show how Model Predictive Control (MPC) can be applied to the problems of induction motor drives and dc-dc conversion, and we illustrate the procedure using two examples: The Direct Torque Control (DTC) of three-phase induction motors and the optimal control of fixed-frequency switch-mode dc-dc converters.

Abstract: The recently introduced approach for modelling and solving the optimal control problem of fixed frequency switch-mode dc-dc converters using hybrid system methodologies is extended to the boost circuit topology, including parasitic elements. The concept of the ni-resolution model is employed to capture the hybrid nature of such circuits. As the resulting equations are nonlinear, two models are formulated, one featuring additional piecewise affine approximations of the nonlinearities and another nonlinear model that retains the nonlinearities in the related system description. An optimal control problem is formulated and solved online for both cases. Simulation results are provided to compare the outcomes of these approaches.