Rotor for an axial flux rotating electrical machine compressed with a band

Abstract

Embodiments involve rotors for axial flux induction rotating electric machines that use a soft magnetic composite for the rotor core. A first embodiment is directed to a rotor for a rotating electrical machine that transmits magnetic flux parallel to a shaft of the rotor. The rotor includes a rotor winding and a plurality of cores. The rotor winding consists of a solid piece of conductive material that comprises a plurality of cavities. Each core is placed in a respective cavity and comprises a highly resistive isotropic ferromagnetic powder.

1 . A rotor for an axial flux rotating electrical machine, the rotor made by a process comprising:
 fabricating a cylindrical rotor winding, the cylindrical rotor winding comprising a plurality of cores, each core substantially equidistant from an axis, wherein each of the plurality of cores is comprised of a compressed ferromagnetic powder;   fabricating a circular band sized such that the circular band applies compression to the cylindrical rotor winding when the circular band and the cylindrical rotor winding are at similar temperatures;   applying a thermal differential between the circular band and the cylindrical rotor winding;   when the thermal differential is applied, inserting the cylindrical rotor winding into an interior of the circular band; and   allowing the thermal differential to dissipate placing the cylindrical rotor winding in compression from the circular band.   
     
     
         2 . The rotor of  claim 1 , wherein the band applies a radial compressive force such that the compressive force reduces radial deformation of the rotor at high angular velocities. 
     
     
         3 . The rotor of  claim 2 , wherein the radial compressive force increases an allowable cyclical loading of the rotor. 
     
     
         4 . The rotor of  claim 1 , wherein the band has portions removed to balance the rotor when the rotor is spinning. 
     
     
         5 . The rotor of  claim 1 , wherein the band has appendages to conduct heat from the rotor winding and to dissipate heat from the rotor into a surrounding gas. 
     
     
         6 . The rotor of  claim 1 , wherein each core of the plurality of cores is not a permanent magnet. 
     
     
         7 . The rotor of  claim 1 , wherein each core of the plurality of cores is isotropic. 
     
     
         8 . The rotor of  claim 1 , wherein the rotor winding comprises a chromium and copper alloy. 
     
     
         9 . The rotor of  claim 1 , wherein each core of the plurality of cores is formed of pressed iron particles. 
     
     
         10 . The rotor of  claim 9 , wherein the pressed iron particles comprise magnetic particles coated with an insulating layer. 
     
     
         11 . The rotor of  claim 10 , wherein the insulating layer comprises silica. 
     
     
         12 . A rotor for an axial flux rotating electrical machine, the rotor made by a process comprising:
 fabricating a cylindrical rotor winding, the cylindrical rotor winding comprising a plurality of cores; and   fabricating a circular band sized such that the circular band applies compression to the cylindrical rotor winding.   
     
     
         13 . The rotor of  claim 12 , wherein the band is made of maraging steel. 
     
     
         14 . The rotor of  claim 12 , wherein each core of the plurality of cores has a magnetic permeability of at least 1. 
     
     
         15 . The rotor of  claim 12 , wherein each core of the plurality of cores has a magnetic permeability of at least 1.5. 
     
     
         16 . The rotor of  claim 12 , wherein each core of the plurality of cores has a saturation magnetic flux density greater than 1.5 T. 
     
     
         17 . The rotor of  claim 12 , wherein each core of the plurality of cores has a saturation magnetic flux density greater than 2.0 T. 
     
     
         18 . The rotor of  claim 12 , wherein each core of the plurality of cores has a magnetic flux density of at least 1.1 T when the core is subjected to a magnetic field of 4,000 Amps/m. 
     
     
         19 . The rotor of  claim 12 , wherein the band applies between of 80 and 300 megapascals of pressure to the rotor winding. 
     
     
         20 . The rotor of  claim 12 , wherein the rotor winding is configured to prevent the compressive force from adversely affecting the plurality of cores.