Abstract: In order to consider the influence on the suspension operation of the inductance difference between direct and quadrature axis in an inset permanent magnet type bearingless motor, a new approach is proposed to realize analytical modeling of the suspension force and its parameter extraction to implement the stable suspension with the rotor saliency. Based on the operation principle of the inset permanent magnet type bearingless motor and the magnetic energy approach, a relatively accurate analytical expression of the magnetic levitation force is established with the rotor saliency effect and the eccentricity in the location of stator and rotor taking into consideration. As the parameter of the levitation force model is the key to control the suspension force and realize the stable suspension operation, the extraction principle of the key parameter is studied, and is realized by the finite element method. Moreover, the control system of the inset permanent magnet type bearingless motor is developed based on the parameters extracted, and then, the simulation result of the suspension operation validate the accuracy of the parameter extraction method.

Key words: Inset permanent magnet type bearingless motor Location eccentricity, Magnetic levitation force, Parameter extraction