Pushing the envelope for electric motors

October 02, 2015 // By Robert Brand, Vacuumschmelze
Engineers developing today’s electric motors focus on power density and efficiency as the two most important parameters. The Hanau-based company Vacuumschmelze GmbH & Co. KG (VAC) supplies advanced magnetic materials and technologies for this purpose, enabling the current boundaries of feasibility to be pushed to higher levels.

Designed for high efficiency, permanently excited synchronous motors account for the majority of modern high-performance motors. A commonly found design is the internal rotor motor, in which a rotor embedded with permanent magnets follows a magnetic alternating field generated by the stator. The alternating field between the stator poles, in turn, is generated by alternating current passing through the stator windings. As the use of a solid stator would result in extremely high eddy current losses, core stacks with electrical isolation between the individual lamination layers are used.

This is where VAC’s materials and technologies can offer definite improvements. Although the electrical steel generally used for such motors is low-cost and universally available, it offers extremely limited magnetization characteristics. VAC’s CoFe alloys are far superior in this respect, as Fig. 1 shows: while the flux density of the common electrical steel type M270-50A is lower than 1.5 T at a field strength of 1000 A/m, the comparable flux density of VACOFLUX® 48 reaches an outstanding level of 2.2 T.

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