Reduction of Tilt Suspension Force Pulsation and Interference in a 4-Pole 6-Slot Axial Maglev Motor

This study presents the design, control strategy, and experimental validation of a 4-pole, 6-slot axial-gap magnetically levitated motor intended for use in implantable artificial heart systems. The proposed motor integrates a permanent magnet stator and a maglev motor structure capable of actively controlling three degrees of freedom (axial and tilt directions), while achieving passive stabilization in the radial directions. To address the issue of tilt-direction suspension force pulsation and interference, a novel control method is introduced. This method employs a pseudo-inverse matrix derived from three-dimensional finite element method analysis to optimize the distribution of control currents and minimize force ripples. The motor's structural and electromagnetic characteristics were analyzed, and its performance was evaluated through both static and dynamic experiments. Static force measurements confirmed that the axial suspension force can be balanced at a 1.5 mm air gap, enabling near-zero control current operation. Dynamic tests demonstrated stable levitation and rotation in both air and water environments, with improved damping and vibration suppression observed in water due to fluid viscosity. The system achieved stable operation up to 2000 rpm in water, while maintaining an experimentally verified controllable axial range of 0.67 mm. These results validate the feasibility of the proposed maglev motor for artificial heart applications. Future work will focus on expanding the levitation range, refining tilt control gains, and redesigning the fluidic housing to incorporate a volute structure with inlet and outlet ports, thereby enabling higher rotational speeds and improved pressure generation suitable for physiological conditions.