Control no Lineal Robusto de una Máquina para Fabricación de Películas Delgadas

Abstract

This paper presents a control scheme for a machine used to make thin films, with a brushless direct current motor, based on the spin-coating method. The nonlinear brushless motor model is included, which corresponds to a three-phase synchronous machine, with rotor flux linkages and stator currents, as the electric dynamics, and the rotor speed, as the mechanical dynamics. In order to achieve the speed regulation, the block control technique was used to obtain a sliding manifold. The sliding mode control technique was applied to ensure that the chosen manifold is attractive and to obtain robustness in the closed - loop system. To complete the control scheme, an observer is included to estimate the unmeasurable states, in this case, the rotor flux linkages. The proposed control scheme was implemented in a machine to make thin films, as well as a controller based on a gain scheduling PID, to perform the comparison of both controllers. The proposed sliding mode control scheme shows some advantages over the PID controller, since the rotor speed regulation is obtained, without steady state error, considering parameter variations.