Design of a time-divided torque and suspension force control type bearingless motor

This paper presents the structure, winding distribution and control circuit topology of the time-divided torque and suspension force control type bearingless motor (BELM). The conventional bearingless motor has separate motor winding and suspension winding in stator core, so outer diameter of this motor is larger than that of the conventional motor in which the shaft is supported by the mechanical bearings. On the other hand, in the proposed BELM, the motor and suspension windings are integrated. Thus, the features of the proposed BELM are simple and smaller in size as compared to the conventional BELM while maintaining the similar torque and suspension force generation capabilities. The detailed design of the proposed motor including the control circuit topology is discussed in this paper. The paper also describes the structure and principle about the torque and suspension force generation of the proposed motor. The control circuit topology and the operation principle are explained in detail. The performance of the proposed BELM is simulated using FE analysis software. A performance comparison of the proposed BELM with the conventional BELM is also provided. The results show that the proposed motor can generate same torque but higher suspension force as compared to the conventional BELM.