Minimization of Cogging Force in a Novel Linear Permanent-Magnet Motor for Artificial Hearts

This paper proposes a novel linear permanent-magnet (PM) motor, termed as double-stator tubular PM (DSTPM) motor, for artificial hearts. The key of the proposed DSTPM motor is to design the appropriate size of the inner and the outer stators so that the inner and the outer cogging forces can be counteracted by each other, thus minimizing the motor cogging force. To achieve this purpose, two stators are designed to have a special angle difference of 90 electrical degrees. Since one stator is located inside the mover, the inner space is fully used. Hence, the thrust density is enhanced and the axial direction length is reduced. Also, the PMs and the redundant windings are set in the stators, and the moving parts have only solid-iron salient poles. The electromagnetic characteristics of the proposed motor are analyzed by using the time-stepping finite-element method, confirming the validity of the proposed motor.