Performance optimization of a bearingless pump using feedback linearization techniques

摘要

The reliability as well as the lifetime of rotating fluid pumps which have to fulfill very high requirements on chemical resistance and purity may be improved considerably when all rotating parts are suspended magnetically with a bearingless motor. A very simple and hence cost-efficient mechanical design can be accomplished when a bearingless slice motor with PM excitation featuring only four concentrated coils is employed. In this paper a nonlinear controller design is presented which improves the performance of the bearingless pump substantially. By means of a nonlinear state transformation and a static state feedback control law the nonlinear mathematical model of the bearingless motor can be transformed into a linear and time-invariant one. Moreover, the resulting linear model may then be split into independent systems for force and torque generation. Accordingly, independent controllers for the rotor position as well as rotational speed can be implemented.