Winding arrangement for an electrical machine

Abstract

A design for and method of winding an electric motor, generator or other electrical machine using multiple strands of wire preformed into a wave shape with a plurality of legs connected by shaped end turns. This results in efficient packing and improved machine performance in terms of both efficiency and power density without the need for flux concentrators. The conductors or windings may be preformed so as to be a self supporting structure, aiding assembly and eliminating the need for an iron core.

We claim: 
     
         1 . A preformed conductor for use in the manufacture of a winding for an electrical machine, the conductor comprising multiple strands of wire and an outer insulating layer, the conductor having a self supporting wave shape comprising a plurality of legs connected by end turns, wherein at least a portion of a least one end turn follows a curved path. 
     
     
         2 . A preformed conductor as claimed in  claim 1 , wherein the cross section of the end turn at at least one point on the curved path, viewed normal to the curved path, is thicker in a radial direction than an axial direction, the radial and axial directions being with respect to the instantaneous centre of curvature of the curved path at the point. 
     
     
         3 . A preformed conductor as claimed in  claim 1 , wherein the curved path is three dimensional. 
     
     
         4 . A preformed conductor as claimed in  claim 3 , wherein the curved path is helical. 
     
     
         5 . A preformed conductor as claimed in  claim 1 , wherein the cross sectional shape of at least one of the legs is approximately rectangular. 
     
     
         6 . A preformed conductor as claimed in  claim 1 , wherein the multiple strands of wire of the conductor comprises at least two sub-bundles of twisted wire strands, each sub-bundle having an outer insulating layer. 
     
     
         7 . A preformed conductor as claimed in  claim 1 , wherein the conductor has a substantially constant cross sectional area. 
     
     
         8 . A method of manufacturing a wave winding for an ironless core electrical machine, the winding comprising at least one conductor arranged into a wave pattern, each conductor comprising multiple strands of wire and an outer insulating layer, the method comprising preforming each conductor such that it has a self supporting wave shape, the wave shape comprising a plurality of legs connected by end turns that progresses around the winding, characterised in that the method further comprises weaving each preformed conductor together to form the wave pattern. 
     
     
         9 . A method of manufacturing a winding as claimed in  claim 8 , wherein the wave pattern is bonded to form a rigid structure. 
     
     
         10 . A method of manufacturing a winding as claimed in  claim 8 , wherein each conductor is made from a length of flexible multi-strand wire, and the conductor is preformed into the self supporting wave shape by pressing the flexible multi-strand wire.