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More powerful, sustainable, economical: voestalpine has set the future of electric motor cooling in motion. Successful development will be followed by a manufacturing process for integrated stator cooling. The material and electrical steel specialists are developing a novel solution for cooling-media-tight, self-bonding varnish rotor stacks.
In contrast with conventional technologies in which only the rotor shaft is cooled, direct cooling in the rotor stack ensures better cooling of the rotor. The new production process will enable electrical steel stacks with media-tight cooling ducts for decisive advantages that are dependent on machine design.
Permanent magnets manufactured from dysprosium, a rare-earth metal, are used in the magnetic excitation field of permanently excited synchronous machines. The rotor cooling developed by voestalpine lowers the engine operating temperature and reduces the proportion of expensive and rarely available dysprosium in the magnets. Rotors can be produced cost-efficiently and sustainably.
Rotor stacks with integrated cooling provide decisive advantages in externally excited machinery. The voestalpine solution leads to a reduction of copper losses in the rotor winding. Lower heat loss levels result in improved efficiency. Higher power density can also be achieved as required through better heat dissipation.
Our patented stator cooling sets a standard. But centrifugal forces make it difficult to achieve rotor tightness because of the high pressure in the cooling medium as it is forced radially against the duct wall. But we have met the challenge successfully.
Ronald Fluch, Project Management
The basis for our considerations was that, as in the stator solution developed by voestalpine, a 100% full-surface bond would not be required. The self-bonding varnish laminations must be absolutely tight in the area of the cooling duct. This involves using the geometric to apply high and localized pressure around the duct. The duct area is very moderately deep-drawn. In contrast with classic punch stacking, however, heavy material damage and shorts are avoided. The technique can also be applied to rotor stacks that can be bonded with self-bonding varnish after being fitted with permanent magnets.
Development partnerships are required to ensure that the production process is completely ready for serial production. The patented manufacturing technology will be made available to interested companies as part of a license model.
