Linear-Rotary Permanent Magnet Actuator With Independent Magnetic Circuit Structure

The paper proposes a novel linear-rotary permanent magnet actuator with an independent magnetic circuit structure, which decreases the coupling relationship between the fluxes of adjacent phases. The amplitude of cogging force is reduced by choosing proper distance between adjacent stator segments in the axial direction, while the thrust force can be increased. A 3-D model is built for analyzing the air gap magnetic flux density and a simplified model of one section is built for calculating thrust force. The expression of cogging force, end force, normal force are derived by analytic method and Maxwell stress tensor method. The analytic results verified by finite element method show that the detent force can be minimized when the distance between two adjacent stators in axial direction approaches 2 tau/3.