Propulsion and levitation control in a linear electrodynamic motor

The control system designed for propulsion and levitation in an experimental electrodynamic linear motor with two degrees of freedom built at University of Sao Paulo is presented in this paper. In the experimental system built, the forces required for propulsion and levitation are determined through the equations that relate the currents in each coil and the variation of the mutual inductance between the fixed coils and the moving coil The resultant equations are undetermined and two ways to calculate the currents were developed and presented previously. The exact solutions had a great harmonic richness therefore an approximation for the current function solutions obtained was developed, implying in a nonlinearity introduced in the system. The approximation was constructed to decouple the propulsion and the levitation dynamics. Using two experimental models developed to describe the dynamics, a SISO control block was designed to control each degree of freedom of the system. The tests achieved so far produced the desired results for the propulsion and levitation control of the system. At this moment the research is directed to solving the problems related to the amplitude of disturbs present in the height of levitation during the operation of the system and the results will be described in a forthcoming paper.