Control of a single parallel winding bearingless machine

This paper proposes a control method for a bearing-less machine (BELM). Unlike most machines that use two separate windings - one for the torque generation and one for the force generation - this study will concentrate on a BELM using a single winding that is able to fulfil the two functions. A model of this BELM was set based on the circuit equation of the electrical machines. Two inductance parameters within the model were introduced to simplify the model of the machine and ease its control. An algebraic formulation of the BELM’s forces is found using an analytical model of the flux changes in the coils as a function of the displacement of the rotor. This is used for the formulation of the energy in the airgap. The obtained results using the analytical model are compared and verified via FEM results. Based on the analytical model of the BELM, a control system that includes a switching functionality for the Voltage Source Inverter (VSI) is implemented to investigate the dynamic control behavior. In addition, a sub-model of the rotating shaft is integrated within the dynamic model to introduce the shaft’s displacement. The obtained results under healthy and different displacement scenarios demonstrate the validity and the performance of the proposed control method for the BELM.