Part 1: What does it take to build a high-speed electric machine?

A review of electric machine technologies in today’s market

In June, I had the opportunity to visit two trade fairs related to rotating machines and explore the options that are offered today by the market.

Coiltech North America

At the first Coiltech North America expo, held in Detroit, the strong trend evident everywhere was electric vehicles (EVs).

In the EV sector, power ratings and load profiles differ from those in industrial applications. Therefore, many items on display were fairly small – typically 10–100 kW – and designed for high power density. In addition, the manufacturing batch sizes are completely different in this sector, making mass production investments more feasible.

The exhibition was filled with electric sheet materials, along with stamping and stack manufacturing technologies. Various winding configurations complemented the stator assembly options, with hairpin winding dominating the sector.

When it comes to rotor components, both stack and squirrel cage manufacturers were present, while permanent magnet technology was almost nonexistent.

It was especially interesting to see the various cooling methods that were offered for integration into electric vehicles. These included, for example, direct liquid cooling of the stator.

In addition, very complex stator and housing geometries were on display. These demonstrated the possibilities additive manufacturing offers for achieving ultimate footprint optimization and power density.

ASME Turbo Expo

Moving from Coiltech to the ASME Turbo Expo in Memphis, this year’s event offered slightly different perspectives on rotating machines. Thus, hydrogen applications were less in focus, while supercritical carbon dioxide (sCO₂) as a process medium was presented at many booths.

Not limited to a single application, sCO₂ can be used in everything from heat pumps to turbines and, of course, carbon capture, utilization and storage (CCUS). As electric machine manufacturers, we need to understand the effects and compatibility of sCO₂ when designing machines for such applications.

Electric drivetrain components were also on display at the expo, but there were no apparent breakthrough technologies. The cooled-down market demand for heat pumps, Organic Rankine Cycle (ORC) systems and hydrogen applications may have resulted in the noticeable lack of both new offerings and existing solutions that benefit from coupling the electric motors and generators with turbomachinery.

Takeaways from the events

Essentially, both exhibitions showed that the building blocks for creating highly specialized electric machines are available on the market – and that applications taking advantage of these electric drives also exist.

Yet, the wider adoption of these applications depends heavily on several factors. These include the push toward zero emissions versus the financial conditions for investing in new technologies – especially when existing “old” solutions are also getting the job done, although with higher operating costs, greater emissions and other drawbacks.

However, as our common goal is to provide a livable future for the following generations, shouldn’t we embrace low-emission technologies and start adopting them right away?