Dynamics of a magnetic gear with two cogging-free operation modes

TL;DR

This paper experimentally investigates the dynamics of a magnetic gear with two specific cogging-free operation modes, revealing phase-locking and complex behaviors explained by a dipole-dipole interaction model with friction.

Contribution

It introduces a detailed experimental analysis of two cogging-free modes in magnetic gears and models their dynamics using dipole interactions plus friction effects.

Findings

Identification of two cogging-free operation modes with phase-locking

Reversal of rotation sense in the two modes

Complex dynamical behaviors at other angles

Abstract

The coupling of two rotating spherical magnets is investigated experimentally. For two specific angles between the input and output rotation axes, a cogging-free coupling is observed, where the driven magnet is phase-locked to the driving one. The striking difference between these two modes of operation is the reversed sense of rotation of the driven magnet. For other angles the experiments reveal a more complex dynamical behavior, which is divided in three different classes. This is done by analysing the deviation from a periodic motion of the driven magnet, and by measuring the total harmonic distortion of this rotation. The experimental results can be understood by a mathematical model based on pure dipole-dipole interaction, with the addition of adequate friction terms.