Transmissions are essential for many mechanical devices. They allow components that rotate at different speeds to work together. For example, the blades of a wind turbine are not directly connected to the electric generator. A transmission takes the relatively low rotational speed of the blades and raises it to the RPM necessary to spin the generator fast enough to produce electricity. Gears are the secret sauce inside any transmission. They are quite reliable, but if one breaks, it can be expensive to repair. And if you’re on top of a wind turbine out at sea, accessing it for a repair can be difficult.
At Texas A&M, Ph.D. student Matthew Gardner is working to replace mechanical gears with magnetic gears. If successful, the result will be smaller, lighter and less expensive drives that transmit power more efficiently. His research is being closely watched by several companies, including ABB, the Swiss-based global technology company.
Magnetic gears require less maintenance, generate less noise and vibrations, and are more durable than mechanical gears. If too much power is applied to a conventional gear, it breaks, but when too much power is applied to a magnetic gear, it just slips away without mechanical damage. In essence, it acts as a clutch built into the transmission that can absorb spikes in applied load without breaking.
” Much of the research in electrical machines represents incremental improvements in technology that has been developed over the past hundreds of years, ” says Gardner.
One of the projects Gardner is working on is building a transmission for a wave power generator. Ocean waves can have huge peaks of energy. The transmission has to be able to reliably absorb high loads over and over again. By definition, repairing a broken component that mounts underwater is a daunting and expensive job.
” Our analysis found that using a magnetic gear generator would be 50% smaller, 50% lighter and 25% cheaper than using a gearless generator for this wave power application, ” says Gardner.
In collaboration with the US Department of Energy and ABB, it has built a prototype transmission with magnetic gears that can handle up to 4000 newton meters of torque. Most of the magnetic gear solutions to date are limited to about 150 newton meters of torque.
” Magnetic gears and magnetic gear machines offer the potential to provide significant, not just incremental, improvement in systems involving electrical machines ,” Gardner said.
Anything that reduces upfront costs and ongoing maintenance expenses for renewable energy systems is a step forward for clean energy. Lowering the costs of renewables will also make nuclear power unprofitable. With magnetic gears, 100% renewable energy becomes a more realistic possibility.
More information: tees.tamu.edu