Principle of a Radial-Foree-Based Electromagnetic Swirling Actuator for Low-Speed Applications

Abstract

This paper proposes an electromagnetic actuator that generates the radial electromagnetic force, as an extension of bearingless motors, and transforms the radial force into the rotating torque through a swirler and an integrated mechanical gear system. The structure and the operating principle of the actuator are introduced. The mathematical derivation of the airgap flux density, the radial force and the gear ratio are presented. FEM analysis is conducted to verify the feasibility of the proposed actuator. It has the potential to realize flat-shape actuator with short axial length, which is suited for low-speed applications such as robotic-joint and wearable-rehabilitation devices.