System and apparatus for axial field rotary energy device

1. An axial field rotary energy device, comprising:

a rotor comprising an axis of rotation and a magnet;

a stator coaxial with the rotor, the stator consisting of a single, monolithic printed circuit board (PCB) having a plurality of PCB layers that are spaced apart in an axial direction, each PCB layer comprises a coil having only two terminals for electrical connections, each coil is continuous and uninterrupted between its only two terminals, each coil consists of a single electrical phase, one of the two terminals of each coil is electrically coupled to another coil on a different PCB layer with a via to define a coil pair, and the coils are connected only with vias;

each coil pair is electrically coupled to another coil pair with another via, and the coils in each coil pair are located on different PCB layers; and

adjacent coils on a given PCB layer are coupled together through one or more coils on one or more other PCB layers, so that a current flowing through a given coil on a given PCB layer flows through at least one coil on another PCB layer before flowing through an adjacent coil on the given PCB layer.

2. The axial field rotary energy device of claim 1 , wherein each PCB layer comprises a plurality of coils, and the coils in each coil pair are co-planar and located on a same PCB layer.

3. The axial field rotary energy device of claim 1 , wherein at least two of the coils are electrically coupled in series.

4. The axial field rotary energy device of claim 1 , wherein at least two of the coils are electrically coupled in parallel.

5. The axial field rotary energy device of claim 1 , wherein at least two of the coils are electrically coupled in parallel, and at least two other coils are electrically coupled in series.

6. The axial field rotary energy device of claim 1 , wherein at least two of the coil pairs are electrically coupled in parallel.

7. The axial field rotary energy device of claim 1 , wherein at least two of the coil pairs are electrically coupled in series.

8. The axial field rotary energy device of claim 1 , wherein at least two of the coil pairs are electrically coupled in parallel, and at least two other coil pairs are electrically coupled in series.

9. The axial field rotary energy device of claim 1 , wherein each PCB layer comprises a plurality of coils that are co-planar and symmetrically spaced apart from each other about the axis, and the coils in adjacent PCB layers, relative to the axis, are circumferentially aligned with each other relative to the axis to define symmetric stacks of coils in the axial direction.

10. The axial field rotary energy device of claim 1 , wherein the stator consists of a single electrical phase.

11. The axial field rotary energy device of claim 1 , wherein the stator comprises at least two electrical phases.

12. The axial field rotary energy device of claim 11 , wherein each PCB layer comprises a plurality of coils for each electrical phase, and the coils for each electrical phase are angularly offset from each other with respect to the axis within each PCB layer to define a desired phase angle shift between the electrical phases.

13. The axial field rotary energy device of claim 1 , wherein each coil is coupled to another coil with only one via.

14. The axial field rotary energy device of claim 1 , wherein each coil pair is coupled to another coil pair with only one via.

15. The axial field rotary energy device of claim 1 , wherein the via comprises a plurality of vias.

16. The axial field rotary energy device of claim 1 , wherein said another via comprises a plurality of vias.

17. An axial field rotary energy device, comprising:

a rotor comprising an axis of rotation and magnets;

a stator coaxial with the rotor, the stator comprising a single, monolithic printed circuit board (PCB) having a plurality of PCB layers that are spaced apart in an axial direction, each PCB layer comprises a plurality of coils, the coils are connected only with vias, and the stator consists of a single electrical phase;

the coils in different PCB layers are directly electrically connected to each other, and the coils within a given PCB layer that are adjacent to each other are not directly electrically connected to each other; and

adjacent coils on a given PCB layer are coupled together through one or more coils on one or more other PCB layers, so that a current flowing through a given coil on a given PCB layer flows through at least one coil on another PCB layer before flowing through an adjacent coil on the given PCB layer.

18. The axial field rotary energy device of claim 17 , wherein the stator comprises pairs of PCB layers, each pair of PCB layers is connected to a different electrical phase, and the pairs of PCB layers connected to different electrical phases are angularly phase shifted by 360°/n electrical degrees about the axis, where n=number of electrical phases.

19. The axial field rotary energy device of claim 18 , wherein each electrical phase comprises a plurality of pairs of PCB layers.

20. The axial field rotary energy device of claim 17 , wherein the stator comprises three pairs of PCB layers, each pair of PCB layers is connected to one phase of a three-phase power source, and the pairs of PCB layers are phase shifted from each other by 120° electrical degrees.

21. The axial field rotary energy device of claim 20 , wherein each of the electrical phases of the three-phase power source comprises a plurality of pairs of PCB layers.