22 Jul 2024


$3.8m project aims for better motors using high-Si steels

A consortium of American researchers has won a $3.8m grant from the US Department of Energy to develop better materials for electric motors, especially for use in transport applications. The project – which includes researchers from Iowa State University, the DOE’s Ames Laboratory, the University of Delaware, and the United Technologies Research Center – is part of a $59.2m federal programme comprising 35 research projects aimed at cutting the costs and improving the efficiencies of electric, alternative-fuel and conventional vehicles.

During the three-year project, the motor researchers will develop stator cores with laminations formed from a new electrical steel containing 6.5% silicon – twice the amount typically found in today’s motors. Jun Cui, an Iowa State University associate professor of materials science and engineering, and a senior scientist with the Ames Laboratory, says that the extra silicon will increase electrical resistivity by about 50%, thus reducing eddy currents, heating and power losses in motors.

Cui foresees the next generation of electric motors running at much higher frequencies – 400Hz, rather than today’s 60Hz. This will lead to higher power densities, resulting in motors that are smaller, lighter, more powerful and more cost-effective.

Running at higher frequencies reduces motor efficiencies, but Cui reports that the new electrical steel can help to minimise those losses.

However, steel containing extra silicon is also brittle and expensive to produce. “It will crack if you drop it,” Cui reports. The researchers will therefore study and characterise different processes for making electrical steel to try to deliver materials that are more ductile and cheaper to manufacture. One technique is to use a spinner that solidifies molten metal rapidly into thin ribbons.

The researchers are also committed to developing materials and motors that do not rely on magnets based on costly rare-earth materials.

“The fundamental drive for this project is that we want more cost-effective and efficient electric motors,” Cui says. “In about 10 years, if we’re lucky, we should see a real impact of this work. We should see these motors on the road.”

The US DOE wants plug-in electric vehicles to be as affordable and convenient as todays internal-combustion machines, within a few years. It is aiming to reduce electric vehicle weights by 30%, battery costs from $500 to $125 per kWh, and the cost/kW of electric drive systems from $30 to $8.