Compensation of Unbalance Forces of a Switched Reluctance Machine with Combined Current and Fluxlinkage Control

The presented work handles the compensation of unbalance forces for a 6/4-Switched Reluctance Machine (SRM), which generate significant radial magnetic forces in an eccentric motor shaft position. When the rotor is operating e.g. in its principal axis of inertia, these forces must be compensated by the bearings. This is of major interest for long term storage Flyweels where bearing efficiency is a key factor for the overall system performance. Due to the back electromotive force (BEMF) in high speed operation, precise current control is a major challenge. Hence a combination of current and fluxlinkage control is used to minimize the generated radial forces. It can be used for low and high speed applications. For the observation of fluxlinkage two different methods are described. The functionallity is shown by means of simulations and measurement.