Electric motors seem like they’re the key to the green energy revolution, a cleaner alternative to the fossil-fuel-guzzling engines that currently power automobiles and machinery. But it turns out electric motors are pretty inefficient. Large industrial motors currently use about 15 percent of the power produced in the United States, wasting about 80 percent of that electricity. There are several reasons why motors are so inefficient, and the bearings that hold the motors in place are one factor. Lubricants needed to keep bearings running can transfer heat, reducing efficiency. Because they wear out quickly, bearings also limit the use of more efficient upgrades like variable speed motor drives.
Eric Severson, assistant professor of electrical and computer engineering at the University of Wisconsin-Madison, hopes that with the support of a prestigious National Science Foundation CAREER award he can develop bearingless magnetic motors that would lead to new types of more efficient, more adaptable motors.
Several research groups are looking into motors which would use magnetic bearings to levitate a motor’s shaft, allowing it to spin without resting on a bearing, essentially creating a friction-free motor. Doing that means the mechanical aspect of the motor can be simplified, but the machine is more electronically complicated.
Severson plans to take that idea one step further, letting the motor serve as its own bearing. His design does that by stripping away redundant parts, like extra battery backups, and simplifying the electronic components. “My design can do the same thing as these magnetic bearings,” he says. “But it uses the magnetic materials that are already in the motor. So, it’s a step more integrated.”
The advantage of non-contact bearings, he says, is that the design decreases cost and allows the motor to be configured in all kinds of shapes and tilted at various angles. Severson believes these motors could replace the energy-draining behemoths currently used in industry, but they could also have other uses. For instance, they would allow the production of very short motors with very large diameters, which could be used in electrified flight. A friction-free motor sealed in a vacuum chamber could also be used as a flywheel to store energy from a green energy grid, converting solar and wind energy to on-demand energy. “There’s no friction because it levitates,” he says. “It would have no self-discharge and wouldn’t slow down.”
At least, that’s how it works in theory. The CAREER award will help Severson and his students test out their designs. “We’re to the point that we’re ready to start building some prototypes and find out how true the assumptions we made really are,” he says.
Severson’s interests aren’t all mechanical. Another part of his CAREER proposal involves outreach. He’s working with 4-H, the youth mentoring organization, to create open source lab kits that will allow participants to do their own magnetic and motor-based investigations. He’s also working with Joanna Skluzacek, the 4-H STEM specialist at UW-Madison, Division of Extension, to develop summer camps at the University’s Upham Woods Outdoor Learning Center in Wisconsin Dells, Wisconsin, where budding engineers can tinker with motors, magnets and other mechanical devices.
4-H holds a special place for Severson, who was part of the organization growing up in rural Chanhassen, Minnesota, and where he completed several engineering projects he displayed at fairs. “My interest really is on trying to create STEM career pathways for rural kids and female youth,” he says. “And I think 4-H is a great network for that.”
Author: Jason Daley