Go ahead. Tell me it can’t be done. We love to challenge convention, pioneer new perspectives – and redefine the possible. Once our dedicated Hi-Lite team accepts the assignment, you are on course for success. Our ultra-thin-gauge electrical steel laminations already handle the highest rotational speeds recorded. Specified for the greenest hybrid vehicles, the most advanced vacuum cleaners and the fastest cars in the F1 circus, Hi-Lite puts a new spin on innovation. So: tell me it can’t be done – and let me prove you wrong. Challenges of manufacturing electrical steel Magnus Lindenmo, head of the electrical steels development team at Surahammar, describes the challenges of manufacturing electrical steel, its many benefits and the evolution of Surahammars Bruk’s Hi-Lite high-speed/low-loss laminated silicon-steel components. “Today’s high-tech electrical steels are essential in the manufacture of the cost-effective stators and rotors needed for a huge range of electric motor applications, as well as in generators and transformers. They ensure high magnetic permeability and low power losses, to secure peak performance. Power losses in electrical steels derive from several factors. Eddy currents, induced by the alternating magnetic field, play a critical role. Rolling steel to a thinner gauge confines these eddy currents to a smaller volume, reducing ‘classical’ eddy current losses. Losses can of course also be limited by increasing the silicon or aluminium content, for improved resistivity.” “Some ten years ago we were among the first in the world to produce thin gauge electrical steels at a 4-high wide-strip mill, making these grades more generally available to the market. Now that some producers cater to this need, we have taken the next step in further facilitating the design, manufacture and use of thin gauge electrical steels – by introducing Hi-Lite.” Quality Control Hi-Lite grades are subject to rigorous quality control procedures throughout their manufacture. Every coil or sheet supplied is fully traceable back to its original heat treatment at the steel plant. The quality management system employed by Cogent Surahammar and all its suppliers is ISO 9001 approved. Most importantly, everyone at Cogent Surahammar have long experience of manufacturing high quality thin-gauge electrical steels. High frequencies – but low losses “For application frequencies beyond the standard 50 or 60 Hz, thinner steel may be needed to maintain low losses. The Hi-Lite range, available with a Suralac®7000 insulating coating, and now also with the Suralac®9000 bonding coating, has been optimized for medium to high fundamental frequencies (200 -2500 Hz) and harmonics up to about 25 kHz. For the most extreme applications, we have developed Hi-Lite NO 10, the thinnest wide strip electrical steel on the market.” “The special qualities of the Hi-Lite range are particularly relevant to today’s automotive industry. Global interest in electric vehicles (EVs) and hybrid electric vehicles (HEVs) is growing dramatically: the key technological enablers for these applications are electric machines (motors), along with their drive systems. Design optimization of electric motors for automotive applications has become an urgent priority.” The problem of stress “The electrical steel in an IPM (Internal Permanent Magnet) electric motor is not only important for minimising losses in the stator. It also plays an important structural role in the rotor. At high rotational speeds of several thousands of rotations per minute (rpm), electrical steel in the rotor can experience high levels of stress. High stresses are particularly prevalent in regions around the magnet slots, where narrow ‘bridges’ keep the magnets in place.” Extending rotor life Since 2007, Surahammars Bruk and Tata Steel Product Engineering group have jointly explored ways of optimizing the durability and efficiency of EV/HEV motors. Particular attention has been paid to understanding the influence of magnet pole arrangements, magnet slot geometry and ‘bridge’ dimensions on rotor fatigue lives and air-gap flux densities. This joint research clearly demonstrates that it is now possible to design durable IPM motor rotors with a service life beyond that of the host EV/HEV vehicle. The design knowledge and unique data on the fatigue properties of electrical steels is now a part of the Hi-Lite concept. Development Although the basic types of thin-gauge electrical steels are based on established technologies, products and processes continue to be improved to meet users’ increasing demands for enhanced properties and greater cost efficiency. Special grades (to satisfy particular strength requirements, for example) can be tailored for specific customers. Much of Cogent Power’s R&D is carried out in cooperation with experts in different fields outside the company. Important R&D partners include Tata Steel as well as respected universities and research institutes like the Wolfson Centre of Magnetics, at Cardiff University. Via our partners, we can offer specialist design support in optimizing the strength and durability of high-speed motor components, as well as assistance with non-standard magnetic measurements. Filter applications “A growing area of interest is filters related to variable speed drives. The principles are the same as for smaller motors for HEV/EV vehicles: higher frequency means higher power density. But this also results in higher frequency harmonics from the converter. The use of Hi-Lite thin electrical steel grades enables the design of energy efficient harmonic filters for these applications.” Supply chain Management We are more than a steel supplier and materials data resource. We can help you select the best supplier of laser cut laminations for prototypes and provide stamped laminations or finished cores through a subcontractor. Backed by the multiple skills of our international network, we’ll help transform your innovative visions into commercial reality. From single elements to the design, manufacture and supply of complete components, the choice is yours.