Design and Analysis of a Surface-Inserted Magnetic Screw With Minimum Thrust Force Ripple

This paper proposes a surface-inserted magnetic screw (SIMS) for electrified aircraft applications, which exhibits low ripple, high force, and simple processing. The key of the proposed SIMS is to adopt unequal segments for minimum thrust force ripple. Firstly, the generation mechanism of the force ripple based on ripple period is investigated. Then, the uniform analytical expressions of force ripple with different segments are derived. Besides, the discrete analysis method is firstly used to evaluate the helical magnetic field. Based on the discrete analysis method, the helical magnetic field can be approximated as axi-symmetric, which greatly simplifying the analysis of force ripple. Afterward, the three-dimensional (3-D) finite element method (FEM) is applied to verify the accuracy of the discrete analysis method. Finally, the correctness of the theoretical analysis is verified by experiments.