Principle and Analysis of Radial-Force-Based Swirling Actuator for Low-Speed High-Torque Applications

This article proposes a swirling actuator that uses the electromagnetic radial force and mechanical gears to generate rotational torque. The proposed actuator generates a rotating radial force between an inner stator and a swirler. The gears on the swirler and outer rotor convert the circular motion of the swirler to low-speed rotor rotation. Thus, the proposed actuator is aimed at low-speed high-torque applications. In this study, the air-gap radial flux density and electromagnetic radial force are investigated analytically and verified through finite-element analysis. The static radial force and output torque are measured in a prototype of the actuator. The system efficiency and the gear efficiency are evaluated. A peak torque density of 27 Nm/L with a small volume of 0.16 L is realized in the prototype.