Dual Magnetic Gear for Improved Power Density in High-Gear-Ratio Applications

Mechanical gears, which have applications in several modern industrial fields, are used mostly for power-transmitting mechanical devices. However, because the mechanical gear operates, in principle, by engaging the gear teeth, it is difficult to avoid problems, e.g., friction loss from physical contact, noise, and vibration. A magnetic-gear design that solves the physical-contact problems of mechanical gears has drawn considerable research attention. A magnetic gear has no mechanical friction loss, creates very little noise or vibration, and does not require lubricants. We attempt to apply magnetic gears to wind-turbine systems, which experience a catastrophic economic loss when the mechanical gears break down. However, a conventional magnetic gear has too low power density to support the high gear ratio required by the wind power-generation system. A novel shape for a high gear ratio is proposed and a design guide is shown.