Lappeenranta University of Technology (LUT) introduces the first electrical motor applying carbon nanotube yarn. The material replaces copper wires in windings. The motor is a step towards lightweight, efficient electric drives. Its output power is 40 W and rotation speed 15000 rpm.
Aiming at upgrading the performance and energy efficiency of electrical machines, higher-conductivity wires are searched for windings. Here, the new technology may revolutionize the industry. The best carbon nanotubes (CNTs) demonstrate conductivities far beyond the best metals; CNT windings may have double the conductivity of copper windings.
”If we keep the design parameters unchanged only replacing copper with carbon nanotube yarns, the Joule losses in windings can be reduced to half of present machine losses. By lighter and more ecological CNT yarn, we can reduce machine dimensions and CO2 emissions in manufacturing and operation. Machines could also be run in higher temperatures,” says Professor Pyrhönen, leading the prototype design at LUT.
No upper limit for conductivity
Traditionally, electrical machine windings are made of copper, having the second best conductivity of metals at room temperature. Despite the high conductivity, most of machine losses occur in copper windings. Carbon nanotube yarn, instead, does not have a pre-defined upper limit for conductivity (values of 100 MS/m measured on individual CNTs).
According to Pyrhönen, electrical machines are so ubiquitous that we often forget their presence. In our homes there can be tens of electrical machines. ”An industrial unit may include thousands of motors, all with copper windings. Thus, finding a more efficient material would revolutionize the industry.”
Carbon replaces copper?
The prototype uses carbon nanotube yarns converted into isolated tape by a Japanese-Dutch company Teijin Aramid, which has developed the spinning technology with Rice University, USA. Industrial applications are still in their infancy; increasing the production capacity and the yarn performance will allow major steps forward in development of innovative products, believes Business Development Manager Dr. Marcin Otto from Teijin Aramid.
“Electrical machines have significant improvement potential; nevertheless, considering material physics, traditional materials are reaching their limits. Here, carbon materials may be the solution: The conductivity of carbon nanotube yarns could be three times that of copper. Further, carbon is abundant while copper must be mined or recycled by industrial processes.”