Research on Electromagnetic Suspension Characteristics of 12-slot 6-Pole Single-winding BL-BLDCM

Abstract

Background: The independent suspension winding in the dual-winding bearingless motor reduces the power density of the motor, and the amplitude of radial magnetic suspension force is affected by the limited slot space. As for the single-winding bearingless brushless direct current motor (BL-BLDCM), although preliminary researches have been carried out, a detailed analysis of its electromagnetic suspension characteristics is lacking. Objective: The magnetic suspension force mathematical model and electromagnetic suspension characteristics are analyzed through a single winding BL-BLDCM with a 12-slot/tooth stator and a 6-pole permanent magnet (PM) rotor. Method: First, the structure and working principle of the motor are introduced, and the mathematical model of the magnetic suspension is derived. Then, through Maxwell software, a twodimensional finite element model of the single-winding BL-BLDCM is established. Finally, the variation of the controllable magnetic suspension force and the coupling radial force along the vertical axis with the key structural parameters such as the air gap length, the PM pole arc coefficient, and the PM thickness are studied. Results: The law of radial controllable magnetic suspension force and the coupling radial force along the vertical axis changing with related parameters is given, and the analytical model of radial magnetic suspension force is verified. Conclusion: The proposed radial suspension force mathematical model is effective; the analysis results of electromagnetic suspension characteristics can provide a reference for the optimal design of single winding BL-BLDCM.