Propulsion control in a linear electrodynamic motor with two degrees of freedom

The study of propulsion 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 fixed coil and the variation of the mutual inductance between the fixed coils and the moving coils. The resultant equations are undetermined and two ways to calculate the currents were developed. One way developed to calculate the currents in the fixed coils for a given propulsion force is based on an optimization approach. A solution to the time varying linear equations is computed off line, giving one possible combination of currents that provides the required propulsion forces in the moving coil. Another way to calculate them uses an inverse matrix exact solution for the time varying linear equations at several points over the fixed coils. The tests achieved so far produced the desired results for the propulsion open loop control of the system. At this moment the research is directed to solving the dynamic problem related to the control of levitation and propulsion simultaneously and the results will be described in a forthcoming paper.