The radial suspension force with a new structure of a bearingless induction motor based on single winding is researched. Compared to the conventional double-winding structure of bearingless induction motor, torque and suspension forces are produced with a single-winding system. Bearingless induction motor is a nonlinear, multi-variable and strong coupling system. It is difficult to obtain an accurate mathematical model on the radial suspension force. So the research method about radial suspension force of a single-winding bearingless induction motor is proposed, based on two fundamentals. Firstly, a new structure and operation principle of a single-winding bearingless induction motor is introduced. Then the air-gap flux density distribution of the single-winding bearingless induction motor is analyzed in detail. The accurate mathematical model of radial suspension force is deduced by using two-fundamental wave method and Maxwell's stress tensor method. Secondly, according to the transient analysis of the single-winding bearingless induction motor which its speed is 6000 r/min, by finite element method (FEM), the component of radial suspension force in x-axis and y-axis is obtained by FEM simulation analysis. The calculation results used by FEM and the theoretical calculation results of mathematical model used by two fundamental wave method have been compared. Thirdly, an experimental prototype is produced, and suspension experiment of prototype is carried out. Then measured result of radial suspension force is analyzed. The analysis results show that the prototype has excellent suspension characteristics, and the mathematical model of radial suspension force based on two-fundamental wave method has low error and high precision.
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