Analytical modeling of the magnetic levitation force for an inset permanent magnet type bearingless motor

Based on the operation principle of inset permanent magnet type bearingless motor and the magnetic energy approach, a relatively accurate analytical expression of the magnetic levitation force was proposed in this paper 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 calculate the suspension force and to realize the stable suspension operation, the extraction of the key parameter was studied in detail and realized by the finite element method. Moreover, the control system of the inset permanent magnet type BLM was developed based on the parameters extracted, and then, the simulation result of the suspension operation validated the accuracy of the parameter extraction method