Nonlinear control for magnetic bearings in deployment test rigs: simulation and experimental results

In this paper three control schemes for a test set-up of a magnetic bearing system for deployment rigs of solar arrays are described. The air gap of the magnet has to be controlled to a constant value independent of the deployment of the solar array. The deployment of the rig has been modeled as a variation in the load of the magnetic bearing. The considered controller design procedures are linear PD, nonlinear PD, and sliding mode. For all three schemes simulations are presented in order to make a comparison. However, the experiments with a test set-up have only been done for the linear PD and the sliding mode control scheme, since they were simple to implement. The results suggest to take the nonlinearities into account, since the nonlinear control schemes give better performance