Detent-Force Minimization of Double-Sided Interior Permanent-Magnet Flat Linear Brushless Motor

New detent-force minimization methodologies for a 6/4 double-sided interior permanent-magnet flat linear brushless motor configured with alternate teeth windings are presented in this paper. Based on the superposition principle, the end-effect and cogging forces are separately minimized using two different techniques. The end-effect force is reduced by a new 2-D optimization using the step-shaped end frames in the slotless stators. The cogging force is minimized through a destructive interference using the slot-phase shift between the upper and lower stators. Each technique is verified experimentally, and the optimal design parameters are formulated using Fourier series. The total detent-force reduction of 94% is achieved as compared with the base model. The steady-state force after applying these new detent-force-free techniques is demonstrated with actual measurements, and also compared with the finite-element analysis result and analytic solution.