Improving Electric Motors

Electric motors keep the modern world moving. Air conditioning, refrigerators, washers, and dryers are major electrical load in millions of homes. Electric motors use more than 60% of all electricity consumed by the industrial sector. Therefore, the U.S. Department of Energy puts a large amount of time and energy into researching ways to increase electric motor efficiency. Even a two or three percent increase in efficiency could mean millions of dollars saved and millions of pounds of carbon dioxide that was not released into the atmosphere. However, achieving that two or three percent increase is difficult and the options for doing so are limited.

Electric motors are quite simple machines. There is copper wire, iron, magnets and two magnetic fields in all electric motors. Due to their simplicity, just trying different materials is a viable way to improve efficiency. However, the problem becomes economics.  There are materials available today that can improve efficiency, but the motors would cost more to produce. One could coat copper with silver to increase efficiency at higher frequencies, but this would not be a benefit at 60 Hertz which is where most AC motors operate. Silver plated copper conductors would definitely be more expensive than normal copper wire.

Motors that use permanent magnets are also more efficient, but again more expensive. This is due to the recent attempt by China to control the supply of Neodymium permanent magnets. The cost of magnets will only be increasing. Fortunately, researchers have found that the higher price of Neodymium could be offset by embedding small slices of magnet inside the induction rotor thus reducing the size of the magnets needed for the motor to operate properly while still yielding a higher efficiency.

Finally, the iron core that is used to generate the magnetic field in most electric motors is the last area of improvement in electric motor manufacturing. Silicon steels have been used instead of iron with success, but the core is still the greatest source of loss in most electric motors.  The transformer (which also utilize large iron cores to operate) industry provides significant materials expertise that has already led to some improvements by companies like Novatorque. More research is needed to improve the efficiency of electric motors.