The electric motor is everywhere. Even more so in the age of the electric car, wind turbines and solar tracking systems. Electric motors use more than 60% of all electricity consumed by the industrial sector. Air conditioning, refrigerators, and washers and dryers are major electrical load in tens of millions of homes.
So the topic of electric motor technology is not a small issue. A few percentage points of efficiency can add up to very significant reduction in electric power consumption. This is why the Department of Energy spends a lot of time and money trying to squeeze the last bit of efficiency out of electric motors.
The options are kind of limited. There is wire, iron and sometimes magnets. There are only two magnetic fields. So there are not a lot of easy options to improve efficiency through a simple material substitution.
The problem is mostly economics. There are exotic materials available that can improve efficiency, but the costs are significant.
Copper is copper, more or less. You can coat it with silver to increase efficiency at higher frequency but this would not be a benefit at 60 Hertz which is where most AC motors operate. Silver plated copper conductors would be more expensive for sure.
Motors that use permanent magnets are generally more expensive. In part this is due to the recent attempt by China to control the supply of Neodymium permanent magnets. While the cost of magnets is not likely to decline to previous prices, there is no shortage of supply from other sources. Researchers found that the higher price premium of Neodymium could be offset by embedding small slices of magnet inside a standard induction rotor to increase it’s efficiency and power density. The reduction in overall motor size leads to other cost savings.
The iron that is used to generate the magnetic field in most electric motors is the final frontier in electric motor manufacturing. While silicon steels have been in use for some time, the core is still the greatest source of loss in most electric motors. The transformer industry provides significant materials expertise that has already led to some amazing improvements by companies like Novatorque.
We should expect more developments like this in the future.
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