Winding arrangement for an electrical machine
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.
1. A wave winding for an ironless core electrical machine, comprising at least one conductor, the conductor comprising multiple strands of wire and an outer insulating layer, and having a wave shape that progresses around the winding comprising a plurality of legs connected by end turns, with at least a portion of at least one end turn following a curved path, wherein the cross section of the end turn at least at 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 center of curvature of the curved path at the point the end turn flattens with respect to the legs to form said cross section, and that the curved path combined with flattening of the end turn relative to the legs allows the end turn of the conductor to be nested with the end turn of a like conductor.
2. A winding for an electrical machine as claimed in claim 1 wherein the curved path is three dimensional.
3. A winding for an electrical machine as claimed in claim 2 wherein the curved path is helical.
4. A winding for an electrical machine as claimed in claim 1 wherein the cross sectional shape of at least one of the legs is approximately rectangular.
5. A winding for an electrical machine as claimed in claim 1 wherein the at least one conductor comprises two or more conductors arranged in a wave pattern.
6. A winding for an electrical machine as claimed in claim 5 wherein the wave pattern has two layers and the at least one conductor comprises at least one pair of conductors, the legs of each pair of conductors being aligned together or skewed to each other at an included acute angle of up to 60 degrees, the legs of each conductor alternating between the two layers with the end turns at each side of the winding being skewed in substantially the same direction such that the end turns do not cross over each other.
7. A winding for an electrical machine as claimed in claim 1 wherein the electrical machine is an axial flux electrical machine, and the winding is tapered such that the active portion of the winding becomes thinner as the radius of the winding increases.
8. A winding for an electrical machine as claimed in claim 7 wherein at least one of the legs of the conductor is tapered such that it becomes thinner in the plane of the wave shape as the radius of the winding decreases.
9. A winding for an electrical machine as claimed in claim 1 wherein the conductor is continuous for at least one complete turn of the electrical machine.
10. A winding for an electrical machine as claimed in claim 1 wherein the multiple strands of wire of the conductor comprise at least two sub-bundles of twisted wire strands, each sub-bundle having an outer insulating layer.
11. A winding for an electrical machine as claimed in claim 1 , wherein the electrical machine is any one of a radial flux machine or a conical flux machine.