Research on Electromagnetic Performance of Claw-Pole Magnetic Levitation Torque Motor for 2D Valve According to Static Eccentricity

The claw-pole magnetically levitated torque motor (CPMLTM) is an electro-mechanical converter that uses the cogging torque between the stator and rotor instead of a mechanical spring for zero-point positioning, and it features a large output angular displacement and a high work-to-weight ratio. In this paper, the effect of static eccentricity on the electromagnetic performance of CPMLTM, including cogging torque, electromagnetic torque, and axial recovery force, is investigated. First, based on finite element method (FEM), the effect of static eccentricity on the air-gap flux density, unbalanced magnetic force (UMF), and static characteristics of the 14-pole/14-slot CPMLTM is investigated. Then the eccentric and non-eccentric prototypes were machined and the FEM results were verified experimentally. The FEM and experimental results show that the static eccentricity can improve the magnetic stiffness and axial recovery force, while the effect of static eccentricity on the electromagnetic torque is negligible; however, the static eccentricity generates the UMF, which increases linearly with the increase of the eccentricity, and it will cause the vibration and noise of the CPMLTM. The magnetic stiffness in the neutral position of the CPMLTM with 60% static eccentricity is 25.8 mNm/°, an improvement of 222%.