Axial flux generators having a flat strip conductor with particular axial widths for long term reliability
An axial flux rotary generator comprising: two magnetic annuli; a coil annulus; the magnetic annuli and coil annulus having a common axis; the two magnetic annuli defining a plurality of magnetic fields around the common axis extending across a gap between the two magnetic annuli and the coil annulus having a sequence of coils around the common axis in the gap such that lines of magnetic flux from the magnetic fields cut the turns of the coils and thus induce electric current in the coils as the magnetic annuli are caused to rotate relative to the coil annulus; characterised in that the coils comprise a wound flat strip conductor.
1. An axial flux rotary generator comprising:
two magnetic annuli;
a coil annulus;
the magnetic annuli and coil annulus having a common axis;
the two magnetic annuli defining a plurality of magnetic fields around the common axis extending across a gap between the two magnetic annuli and the coil annulus having a sequence of coils each coil being wound spirally in a layer, the sequence of coils being around the common axis in the gap such that lines of magnetic flux from the magnetic fields cut the turns of the coils and thus induce electric current in the coils as the magnetic annuli are caused to rotate relative to the coil annulus;
wherein the coils comprise a wound flat strip conductor;
wherein the flat strip conductor has an axial width of within +1% and −5% of the axial width of the coil annulus and the axial width of the coils is within +1% and −5% of the axial width of the coil annulus.
2. The axial flux generator of claim 1 , wherein the flat strip conductor has an axial width of between +0% and −2% of the axial width of the coil annulus.
3. The axial flux generator of claim 1 , wherein the flat strip conductor is insulated by a layer of electrically insulating material on one or both flat sides.
4. The axial flux generator of claim 3 , wherein the one or both flat sides are anodised to provide the layer of electrically insulating material.
5. The axial flux generator of claim 3 , wherein a thickness of the layer of electrically insulating material is 1-5 μm.
6. The axial flux generator of claim 1 , in which the width of the flat strip conductor is several times, or more, than a thickness of the flat strip conductor.
7. The axial flux generator of claim 1 , in which the material of the flat strip conductor used to form the coil is aluminium.
8. The axial flux generator of claim 1 , in which the flat strip conductors used for the coils have an axial width of 60 mm or less.
9. The axial flux generator of claim 1 , wherein magnets of the magnetic annuli are ferrite permanent magnets.
10. The axial flux generator of claim 1 , wherein an axial width of permanent magnets of the magnetic annuli is at least twice the axial width of a coil of the coil annulus.
11. The axial flux generator of claim 1 , wherein the coils have an elliptical cross-section.