Metrology of magnetic losses in electrical steel sheets for high-efficiency energy conversion

Steel sheets are central to electric motors, generators, and transformers that produce and convert virtually all energy from conventional and renewable sources. These sheets undergo periodic magnetisation during operation causing up to 10 % of the energy produced to be lost. International standards and the European Ecodesign Directive specify minimum efficiencies for energy-using devices, but testing fails to consider real-world operational temperatures or the higher power levels of modern devices. The microstructure of a sheet also impacts on energy loss, yet no systematic investigations have linked micro-defects to standardised measurements.

The project examined two standard energy tests at extended frequencies and power levels and devised new measurements for power loss at temperatures up to 155°C with results validated by round-robin comparisons. The effects of mechanical damage at the micro and nanometre level on efficiency measurements were also examined. The construction of higher efficiency machinery will reduce energy losses, allow existing regulations to be met and help the EU meet the 32.5 % efficiency target for 2030 set out in the EC Energy efficiency directive.