Would providing a cooler environment improve motor efficiency?

[hockeyoligist2]

After reading the article below I started thinking, how much would could you gain on a regular motor?


Sumitomo Electric has developed what is being called the world?s first automobile powered by a superconducting motor. The electric passenger sedan (a modified Toyota Crown Comfort), which is powered by a 365-kilowatt high-temperature superconducting motor cooled by liquid nitrogen, was unveiled in Osaka on June 12 and will go on display at the Hokkaido Toyako G8 Summit on June 19.

Superconductors ? energy-efficient materials that can carry electrical current without resistance ? are used in applications ranging from medical devices to linear motors for trains. Until now, however, they have never been used to power an automobile, says Sumitomo.

Sumitomo?s motor uses high-temperature superconducting wires instead of the copper wire typically used in the coils in electric vehicle motors. When cooled to an extremely low temperature, electrical resistance and current loss are reduced to nearly zero, so the motor can operate with greater energy efficiency and torque ? in other words, the motor uses less electricity to do the same amount of work. The company says the prototype vehicle can travel 10% farther than conventional electric vehicles running on the same type of battery.

The development comes as demand for electric vehicles grows, and as manufacturers step up efforts to improve battery and motor performance to increase the distance that vehicles can travel on a single charge.

Sumitomo intends to further improve the motor with the aim of putting a vehicle on the market in the not-too-distant future. The company is looking to develop superconductor motors for buses and trucks as well.




http://www.pinktentacle.com/2008/06/superconductor-electric-vehicle/

 

[broadgage]

I believe that there would be an efficiency gain in cooling a regular (non superconducting) electric motor.
The gain would be very small however.
There are three sources of loss in an electric motor.
Iron losses- these are eddy current losses in the magnetic circuit, and are not affected by temperature changes.
Friction losses- these are caused by friction in the bearings, and by air resistance as the armature rotates in air. These losses would not be reduced at a lower temperature and would probably increase very slightly since air is denser at lower temperatures, and lubricants are more viscous.
The other source of loss is the resistance loss in the copper windings, this would be reduced at lower temperatures, since the resistance of the windings would be less. The saving would not be much however, since the losses in a motor are not that high, copper losses are only a part of the losses, and said copper losses would only slightly reduce.

It is generally desirable to reduce the operating temperature of a motor but this is primarily to prolong the life of the unit, not to increase efficiency.

 

[crossman]

Off the original topic, but this is more energy efficient? What about the production of liquid nitrogen? How much energy is used in cooling the nitorgen to XXXX degrees below zero? How often will the car have to have liquid nitrogen added? How much does the liquid nitrogen cost?

I have to feel certain that the energy expended in the production of liquid nitrogen is greater than the energy saved by a more efficient motor.