Multi-pole rotating electromechanical devices, such as motors, generators, re-gen motors, alternators, brakes and magnetic bearings are comprised of rotors and electro-mechanical components. AC motors rotate by producing a rotating magnetic field pattern in the electro-mechanical component that causes the rotor to follow the rotation of this field pattern. As the frequency varies, the speed of the rotor varies. To increase the speed of the motor, the frequency of the input source must be increased.
High frequency motors manufactured with the proper materials can be very efficient. For certain applications, like electric or hybrid cars, highly efficient electric motors are desirable.
The construction of electro-mechanical components for high frequency electric motors and generators is problematic. Iron or steel components are quite common in electric motors and generators. However, at high frequencies, such as those greater than 400 Hz, conventional iron or steel components are no longer practical. The high frequency of the AC source increases the core losses of the iron or steel components, reducing the overall efficiency of the motor. Additionally, at very high frequencies, the component may become extremely hot, cannot be cooled by any reasonably acceptable means and may cause motor failure.
For construction of electro-mechanical components used in high frequency electric motors, ribbon made from soft magnetic material provides distinct advantages. Examples of soft magnetic ribbon materials would be either 1) conventional material typically defined as 0.008″ and thicker, non grain oriented with a typical Si content of 3%+/− ½% or 2) alternate soft materials that are 0.007″ or thinner with Si content of 3% to 7%, amorphous, or nanocrystalline alloys and other grain oriented or non grain oriented alloys. Some soft magnetic ribbon materials exhibit inherent characteristics that make their use in high frequency electro-mechanical rotating devices highly desirable. Some soft magnetic ribbons are easy to magnetize and demagnetize, which means an electro-mechanical component made with these metals would have low power loss, low temperature rise at high frequency, extremely fast magnetization and easy conversion of electrical to mechanical energy. An electro-mechanical component made of such an metal would generate less core losses and be able to operate at much higher frequencies, resulting in motors and generators of exceptional efficiency and power density.
Soft magnetic materials are commercially produced as ribbon or strip. A preferred example of a soft magnetic metal ribbon is Metglas®, which is an amorphous material, manufactured by Honeywell, Inc. Soft magnetic metal ribbons are very thin and of varying width. Manufacturing components of soft magnetic metal ribbon requires winding the soft magnetic ribbon into a shape and then heat processing the shape. Simple three dimensional shapes, such as toroids, can currently be constructed from soft magnetic metal ribbon.
However electro-mechanical components are often not simple three dimensional shapes. The electro-mechanical component can have numerous slots for accommodating motor coils in a generally toroidal structure.
Attempts to create complex three dimensional configurations from soft magnetic metal ribbon have heretofore been commercially unsuccessful. Various manufacturing techniques have been attempted by industry such as but not limited to: wire electrical discharge machining, electrochemical creep grinding, conventional electrical discharge machining, cutting, stamping, acid etching and fine blanking. None have proven satisfactory for reasons such as cost-effectiveness, manufacturing repeatability, or process cycle time.
This inability to fabricate complex three dimensional shapes from soft magnetic ribbon has been the significant impediment to producing high efficiency axial flux motors and generators. A method to produce electro-mechanical components from soft magnetic ribbon in a cost effective, end use functional, high volume capable method that will also provide substantial design flexibility for end use requirements is highly desirable.