• Description

    A magnetic gearbox (MG) can operate with low noise and vibration and its noncontact operation means that no gear lubrication is required. In addition, MGs have the unique ability to pole slip when overloaded rather than catastrophically failing, thereby providing built-in overload protection. An MG also has the potential for high efficiency. Coaxial MGs have experimentally been shown to be capable of achieving active region torque densities above 200 Nm/L. However, to-date single-stage coaxial MG designs have only been shown to be capable of achieving a high-torque density at a low gear ratio, typically less than 8:1. There are many applications in which a significantly higher gear ratio is desirable, such as in robotic and power generation applications.

    Mechanical cycloidal gearboxes are well known for their ability to have a high gear ratio and a high-torque density. However, their operational life is relatively low. In 2008, a paper demonstrating the capability of a contact-free cycloidal MG (CMG) was published by Jorgensen. Jorgensen demonstrated that a cycloidal rotor motion enables field harmonic modulation to be created between two magnetic rotors. Using a CMG with surface-mounted magnets, it was calculated that a CMG could achieve a peak volumetric torque density of 183 Nm/L at a gear ratio of −21:1. Rens et al. demonstrated the capability of a dual stage −360:1 gear ratio CMG in which each stage of the CMG had a 150 Nm/L torque density. Recently, Chicurel-Uziel experimentally demonstrated the performance of a similar type of CMG with a 26:1 gear ratio. Davey et al. showed that an axial-type CMG can also be built. Davey et al. studied the performance of a 30:1 gear ratio axial CMG. Despite these recent publications, very little research has been published which looks at the capabilities of the CMG. The purpose of this research is to demonstrate that a CMG is capable of achieving a volumetric torque density >200 Nm/L while also operating with a high gear ratio.

  • What problems were resolved?

    A cycloidal magnetic gear with a high gear ratio and a high torque density was designed and simulated.

    The cycloidal motion was successfully simulated in Infolytica Magnet so that the performance (peak torque, losses, efficiency, etc) of the magnetic gear could be evaluated.

  • Technical Level


Kang Li

Kang Li – University of North Carolina at Charlotte

I received my Bachelor’s degree from Shanghai University, China in 2011 and my Master’s degree in Electrical Engineering from Shanghai University, China in 2013. I’m currently pursuing my Ph.D.’s degree at the University of North Carolina at Charlotte. My research interest is in the area of applied Electromagnetics. My research work includes investigating the torque capabilities of high gear ratio magnetic gearboxes.