Analysis of the bearingless AC homopolar motor

The bearingless ac homopolar motor has numerous advantages over classical machines for applications such as flywheel energy storage and as a superconducting machine. In this paper, the bearingless ac homopolar motor is analyzed. Inductance matrices, alignment and reluctance torque calculations, suspension winding configurations, and radial suspension force calculations are presented for two rotor structures. Unlike previous literature, expressions for torque interference caused by suspension force winding configurations and effects of d-axis flux on suspension forces are developed and presented. Furthermore, it is demonstrated that each rotor structure can be analyzed as an equivalent classical machine to allow for easy comparison.