09 Sep '14 14:41>5 edits
http://phys.org/news/2014-09-tabletop-motor-principle.html
"...."We have proven the concept of a new motor that uses electric fields rather than magnetic fields to transform electricity into a rotary force,"
....
The distinction may sound minor, but it could solve a number of practical problems while saving money,
Actually, the concept is not entirely new: Benjamin Franklin and others described and built motors based on electrostatic forces back in the 18th and 19th centuries, but none achieved practical operation. Since the widespread adoption of electric motors a century ago, magnetism has been the only practical source of rotation. Magnetism is easier to exploit than electrostatic fields due to the properties of naturally occurring materials and simple engineering techniques. However, new advances in materials, mechanical engineering and advanced manufacturing may enable electrostatic motors.
In 2011, while Ludois was finishing a Ph.D. thesis at UW-Madison, he realized 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. The new technique, he realized, could deliver major advantages in weight, material cost, operating efficiency and maintenance requirements.
In the motor on display, nested stationary and rotating plates are held hairs-width apart by a unique air-cushioning strategy. An electric voltage delivered to the fixed plates creates an electrostatic field that attracts the rotating plates in a way that forces them to spin.
The breakthrough relies on electronics that precisely control a high-voltage, high-frequency electric field and fluid mechanics to keep the surfaces close without touching. "Nothing is touching, because you are using electric fields to couple the stationary and rotating parts," Ludois says. "There is no contact, and no maintenance.
Because motors and generators are essentially mirror images of each other, the invention may first meet the market in the form of a generator for wind turbines,
....
By saving weight and materials, and boosting efficiency, the new design should give the company a bottom-line advantage. The new design avoids the use of precious "rare earth" metals and substitutes aluminum for the more expensive copper found in magnet windings of conventional motors and generators.
...
..."
I had independently once thought roughly along the same lines but sadly didn't have the means to take the idea any further.
I note that they mention "boosting efficiency" above but wonder if they can really boost energy efficiency by getting rid of the magnets because I happen to know that the most energy efficient electric motors and generators to date are a vary impressive 98% energy efficient which I assume would be rather hard to beat!? I know that often the main loses from conventional motors come from the resistance in the magnetic windings but, at the cost of reducing power density and also more manufacturing cost of the windings, it is simple enough to replace the windings with thicker ones that produce very little lose.
"...."We have proven the concept of a new motor that uses electric fields rather than magnetic fields to transform electricity into a rotary force,"
....
The distinction may sound minor, but it could solve a number of practical problems while saving money,
Actually, the concept is not entirely new: Benjamin Franklin and others described and built motors based on electrostatic forces back in the 18th and 19th centuries, but none achieved practical operation. Since the widespread adoption of electric motors a century ago, magnetism has been the only practical source of rotation. Magnetism is easier to exploit than electrostatic fields due to the properties of naturally occurring materials and simple engineering techniques. However, new advances in materials, mechanical engineering and advanced manufacturing may enable electrostatic motors.
In 2011, while Ludois was finishing a Ph.D. thesis at UW-Madison, he realized 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. The new technique, he realized, could deliver major advantages in weight, material cost, operating efficiency and maintenance requirements.
In the motor on display, nested stationary and rotating plates are held hairs-width apart by a unique air-cushioning strategy. An electric voltage delivered to the fixed plates creates an electrostatic field that attracts the rotating plates in a way that forces them to spin.
The breakthrough relies on electronics that precisely control a high-voltage, high-frequency electric field and fluid mechanics to keep the surfaces close without touching. "Nothing is touching, because you are using electric fields to couple the stationary and rotating parts," Ludois says. "There is no contact, and no maintenance.
Because motors and generators are essentially mirror images of each other, the invention may first meet the market in the form of a generator for wind turbines,
....
By saving weight and materials, and boosting efficiency, the new design should give the company a bottom-line advantage. The new design avoids the use of precious "rare earth" metals and substitutes aluminum for the more expensive copper found in magnet windings of conventional motors and generators.
...
..."
I had independently once thought roughly along the same lines but sadly didn't have the means to take the idea any further.
I note that they mention "boosting efficiency" above but wonder if they can really boost energy efficiency by getting rid of the magnets because I happen to know that the most energy efficient electric motors and generators to date are a vary impressive 98% energy efficient which I assume would be rather hard to beat!? I know that often the main loses from conventional motors come from the resistance in the magnetic windings but, at the cost of reducing power density and also more manufacturing cost of the windings, it is simple enough to replace the windings with thicker ones that produce very little lose.