Highest demands are placed on performance and efficiency of modern traction motors.
To achieve this, electrical steel must have the lowest possible remagnetization losses and high magnetic polarization and strength. These requirements are sometimes contradictory, but thyssenkrupp Steel has resolved the conflict with the help of an optimized alloy concept.
The newly developed e-mobility top grades of the type 025-125Y420 and 020-120Y420 – with a thickness of only 0.25 and 0.20 millimeters – have minimal remagnetization losses and a guaranteed minimum yield strength (Rp0.2 ) of 420 MPa thanks to an optimized alloy concept. Compared to the best predecessor grade in the same strength class from thyssenkrupp Steel, the magnetization losses have been reduced from a maximum of 14 W/kg (027-140Y420) to a maximum of 12.5 W/kg and only 12.0 W/kg (at 400 Hz and 1 T). With these values, the new products are among the leaders of the grades available in Europe and are therefore top grades in the e-mobility segment. The characteristics typical of the grade are even higher.
New premium grades achieve top marks for magnetism and strength
Improved efficiency for electric motors: Greater range or smaller battery thanks to 025-125Y420 and 020-120Y420.
The remagnetization loss is significantly influenced by the sheet thickness, chosen alloy, and manufacturing process of the material. It determines how efficiently a motor uses electri cal energy and can convert it into rotational energy. A low remagnetization loss in an electric motor is synonymous with high efficiency. If the efficiency increases, an electric vehicle can travel more kilometers on a single battery charge, or the battery capacity can be reduced while maintaining the same range. This saves weight and costs. We have further improved the top grade 025-125Y420, which already has excellent conversion losses, by a full 0.5 W/kg through extensive optimizations in our production and the use of new production equipment. The latest top grade 020-120Y420 is an even better NGO grade for super-efficient drive motors. High-speed drive motors in modern electric vehicles not only require excellent magnetic properties, they also place high demands on the mechanical properties of the electrical steel – primarily on the strength of the material. A guaranteed minimum yield strength of 420 MPa provides the necessary strength reserve even for high-performance drives and the opportunity to positively influence the motor design, for example in terms of compactness. In conjunction with state-of-the-art production facilities for NGO electrical steel of the highest quality, this enables significant contributions to be made to efficiency and sustainability in the powertrain.
It's all in the combination: maximum efficiency in combination with our adhesive insulating varnishes
In addition to the quality of the electrical steel used, its processing into rotor and stator packages also plays a decisive role in achieving maximum efficiency in electric motors. Our stabosol® adhesive insulation system offers not only technological but also economic efficiency advantages.
In contrast to the processes commonly used in large-scale production, such as stamping and welding, the material pro perties of the electrical steel strip for the end product, the motor, are optimally preserved in adhesive bonding: Adhesive systems prevent the adverse effects of mechanical joining of laminations, which include material damage and short circuits. Bonded stacking minimizes losses due to unwanted current paths and disturbances in the magnetic flux, enabling the construction of electric motors with significantly higher efficiency and power density. Overall, motor losses can be significantly reduced by adhesive bonding compared to stamping. Tests with prototypes developed in-house on our own research test bench for traction motors show that adhesive bonding can reduce motor losses by up to 16 % depending on the operating point. Further impro vement is possible. stabosol® is an adhesive insulation system that meets high requirements for long-term thermal stability – tested under thermal stress up to 200 °C – and package tightness, even at comparatively low baking temperatures. This is particularly important with regard to modern cooling systems in highly efficient electric motors. stabosol® can be processed in two different ways. In the offline process, the package bonded with stabosol® is cured in a separate oven process similar to that used for baking varnish. However, lower activation temperatures and cycle times are required here.
The inline process, currently under development, on the other hand, involves punching and packaging, including curing of the adhesive bond, directly in the punching tool. This offers further economic advantages, for example in terms of cycle time.
Further details on our insulation varnishes and adhesive packaging solutions can be found in our product overview "Insulation types" on our website.
E-mobility top grades for large-volume series production on state-of-the-art equipment – Made in Europe
In order to achieve the demanding product properties and high quality of the electrical steel strips, the bar is set high for our modern production facilities
That is why thyssenkrupp Steel has invested in a state-of-the art double reversing mill and a coupled annealing and insula tion line at its Bochum site. This configuration enables thin electrical steel strips with high flatness and the tightest thick ness tolerances to be rolled and manufactured with particularly homogeneous mechanical and magnetic properties. Series production of the new NGO25 and NGO20 grades will be ram ped up on these new, state-of-the-art facilities at the Bochum site. With these modern, energy-saving units, thyssenkrupp Steel is expanding its capabilities in the production of non-grain- oriented electrical steel in such a way that it can best meet the growing demand for thinner and highly siliconized materials. And all this is “Made in Europe” – top quality with high level of consulting expertise on site and a reliable supply chain for the whole of Europe.
