Electrostatic motor ‘out-performs standard designs’
An American start-up company is developing a novel motor technology that harnesses electrostatic forces instead of electromagnetism. Wisconsin-based C-Motive Technologies predicts that its technology could produce the lightest, most reliable, energy and cost-efficient electric motors, and non-contact power transfer devices, on the market. It adds that its C-Machine motors will produce high torque at a lower cost than any other motor available or under development.
Rather than relying on magnetic fields to create mechanical motion, the technology harnesses the electrostatic (static cling) force of electric fields. C-Motive’s motors use this force to align closely stacked stationary and rotating aluminium plates.
“We have proven the concept of a new motor that uses electric fields rather than magnetic fields to transform electricity into a rotary force,” explains the company's co-founder, Dan Ludois, who is also an assistant professor of electrical and computer engineering at the University of Wisconsin in Madison. The development could solve a number of practical problems while saving money, he adds.
A C-Machine motor is smaller than a conventional motor, operates without a gearbox, and eliminates the need for copper windings, electrical steel laminations and rare-earth magnets. It is designed to run at 95% efficiency, cutting losses by a factor of three compared to conventional motors. It is also low-maintenance because it is built from low-cost stacked and recyclable aluminium plates that are flexible and adjust themselves automatically, almost eliminating the need for downtime and cutting repair costs.
Electrostatic motors are not new. Benjamin Franklin and others described and built motors based on electrostatic forces in the 18th and 19th centuries, but none achieved practical operation.
Since the widespread adoption of electric motors more than a century ago, magnetism has been the only practical source of rotation. However, Ludois and his colleagues believe that advances in materials, mechanical engineering and manufacturing techniques could now revive the electrostatic motor.
When Ludois was working on his PhD thesis in 2011, he realised that instead of relying on magnetic fields, he could achieve a similar result by manipulating electric fields to create a motor based on electrostatic attraction.
In 2012, Ludois and two other PhD students set up C-Motive to develop and commercialise his ideas. The company’s non-contact capacitive power conversion technology allows power to be transferred wirelessly and could replace high-maintenance slip-rings and brushless exciters while improving control over electric machinery. The technology occupies half the volume of a standard brushless exciter and weighs a tenth as much.
C-Motive says that its innovations allow electrical charges to be stored in high enough densities to produce practical motion on an industrial scale. The secret rests in a patented technology which controls and harnesses these potentially unwieldy forces.