Improved planar composite structures and assemblies for axial flux motors and generators

Abstract

Providing improved planar composite structures and assemblies for axial flux motors and generators. A planar composite structure (PCS) for use in an axial flux motor or generator may include a conductive layer disposed on a dielectric layer, the conductive layer having conductive traces that, when energized, form portions of at least two windings that generate magnetic flux for at least two corresponding phases of the motor or generator. The PCS may additionally or alternatively include a first conductive layer having a first conductive trace that, when energized, forms a first portion of the winding that generates magnetic flux for a first phase of the motor or generator, and a second conductive layer having a second conductive trace different from the at least one first conductive layer that forms a second portion of the winding. The first portion of the winding may be connected in series with the second portion of the winding, and the first and second portions of the winding may be configured and arranged so that the same amount of current flows through each of the first and second portions of the winding.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to each of (A) U.S. Patent Application No. 15 / 852,972, filed December 22, 2017, entitled "PLANAR COMPOSITE STRUCTURES AND ASSEMBLIES FOR AXIAL FLUX MOTORS AND GENERATORS," and (B) U.S. Provisional Patent Application No. 62 / 530,552, filed July 10, 2017, entitled "STRUCTURES AND METHODS OF STACKING SUBASSEMBLIES IN PLANAR COMPOSITE STATORS TO OBTAIN HIGHER WORKING VOLTAGES." The contents of each of the above applications, publications, and patents are incorporated herein by reference in their entirety for all purposes. [Background technology]

[0002] The use of planar composite structures (PCS) as stators in axial flux motors or generators is known, and an example of such a stator is described in U.S. Patent No. 7,109,625 (the "'625 patent"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,109,625 Summary of the Invention [Means for solving the problem]

[0004] In some embodiments, a planar composite structure (PCS) for use in an axial flux motor or generator includes a dielectric layer and a first conductive layer disposed on the dielectric layer, the first conductive layer including first conductive traces that form a first portion of a first winding that, when energized, generates magnetic flux for a first phase of the motor or generator, and a first portion of a second winding that, when energized, generates magnetic flux for a second phase of the motor or generator.

[0005] In some embodiments, a planar composite structure (PCS) for use in an axial flux motor or generator includes a dielectric layer, a first conductive layer located on a first side of the dielectric layer, and a second conductive layer located on a second side of the dielectric layer. The first conductive layer includes a first conductive trace that forms a first portion of a winding that, when energized, generates magnetic flux for a first phase of the motor or generator. The second conductive layer includes a second conductive trace that forms a second portion of the winding. The first portion of the winding is connected in series with the second portion of the winding, and the first and second portions of the winding are configured and arranged so that the same amount of current flows through each of the first and second portions of the winding.

[0006] In some embodiments, a planar composite structure (PCS) for use in an axial flux motor or generator comprises a first conductive layer comprising a first conductive trace, a second conductive layer comprising a second conductive trace, a third conductive layer comprising a third conductive trace, and a fourth conductive layer comprising a fourth conductive trace, wherein the first conductive trace comprises a first radial conductor extending radially from a first radial distance to a second radial distance greater than the first radial distance, the second conductive trace comprises a second radial conductor extending radially from the first radial distance to the second radial distance, the third conductive trace comprises a third radial conductor extending radially from the first radial distance to the second radial distance, and the fourth conductive trace comprises a fourth radial conductor extending radially from the first radial distance to the second radial distance. The first radial conductors are electrically connected to corresponding ones of the second radial conductors by first blind or buried vias, and the third radial conductors are electrically connected to corresponding ones of the fourth radial conductors by second blind or buried vias.

[0007] In some embodiments, a planar composite structure (PCS) for use in an axial flux motor or generator includes a subassembly having a first conductive layer including first radial conductors extending radially from a first radial distance to a second radial distance greater than the first radial distance, first end-turn conductors, and second end-turn conductors. The first end-turn conductors interconnect a first group of the first radial conductors to form a first winding for a first phase of the axial flux motor or generator. The second end-turn conductors interconnect a second group of the first radial conductors to form a second winding for a second phase of the axial flux motor or generator. The first subassembly includes more second end-turn conductors than the first end-turn conductors. The present invention provides, for example, the following. (Item 1) 1. A planar composite structure (PCS) for use in an axial flux motor or generator, said PCS comprising: a dielectric layer; a first conductive layer disposed on the dielectric layer; and Equipped with The first conductive layer comprises a first conductive trace, the first conductive trace comprising: a first portion of a first winding that, when energized, generates magnetic flux for a first phase of the motor or generator; a first portion of a second winding that, when energized, generates magnetic flux for a second phase of said motor or generator; Forming PCS. (Item 2) The first conductive trace comprises: first radial conductors, each of the first radial conductors extending radially between at least a first radial distance and a second radial distance greater than the first radial distance; a first conductive end turn; and Equipped with Item 1. The PCS of item 1, wherein each of the first conductive end turns interconnects a respective pair of the first radial conductors. (Item 3) the first conductive end turn comprises a first outer end turn and a second outer end turn; the first outer end turn electrically interconnects portions of a first pair of the first radial conductors at the second radial distance; the second outer end turn electrically interconnects portions of a second pair of the first radial conductors at the second radial distance; the first portion of the first winding comprises the first outer end turn; Item 3. The PCS of item 2, wherein the first portion of the second winding comprises the second outer end turn. (Item 4) the first conductive end turn comprises a first inner end turn and a second inner end turn; the first inner end turn electrically interconnects portions of a first pair of the first radial conductors at the first radial distance; the second inner end turn electrically interconnects portions of a second pair of the first radial conductors at the first radial distance; the first portion of the first winding comprises the first inner end turn; Item 3. The PCS of item 2, wherein the first portion of the second winding comprises the second inner end turn. (Item 5) the first winding includes a second portion electrically connected in series with the first portion of the first winding; the first conductive end turn further comprises a first outer end turn; the first outer end turn electrically interconnects a portion of one of the first pair of first radial conductors at the second radial distance with a portion of another of the first radial conductors at the second radial distance; Item 5. The PCS of item 4, wherein the second portion of the first winding comprises the first outer end turn. (Item 6) Item 6. The PCS of item 5, wherein the first inner end turn and the first outer end turn are arranged such that the first and second portions of the first winding form a serpentine pattern. (Item 7) the first conductive layer is on a first side of the dielectric layer; the PCS further comprising a second conductive layer located on a second side of the dielectric layer; 7. The PCS of claim 5 or 6, wherein the second conductive layer comprises a second conductive trace forming a third portion of the first winding, the third portion of the first winding being connected in series with the second portion of the first winding. (Item 8) The second conductive trace comprises: second radial conductors, each of the second radial conductors extending radially between at least the first radial distance and the second radial distance, and each of the second radial conductors electrically connected to a corresponding one of the first radial conductors; a second conductive end turn; Equipped with Item 8. The PCS of item 7, wherein each of the second conductive end turns interconnects a respective pair of the second radial conductors. (Item 9) the second conductive end turn comprises a third inner end turn; the third inner end turn electrically interconnects portions of a first pair of the second radial conductors at the first radial distance; Item 9. The PCS of item 8, wherein the third portion of the first winding comprises the third inner end turn. (Item 10) the first winding includes a fourth portion electrically connected in series with the third portion of the first winding; the first conductive end turn further comprises a second outer end turn; the second outer end turn electrically interconnects portions of a second pair of the second radial conductors at the second radial distance; 10. The PCS of claim 8 or 9, wherein the fourth portion of the first winding comprises the second outer end turn. (Item 11) the first winding includes a fourth portion electrically connected in series with the third portion of the first winding; the second conductive end turn further comprises a second outer end turn; the second outer end turn electrically interconnects a portion of one of the first pair of second radial conductors at the second radial distance with a portion of another of the second radial conductors at the second radial distance; 10. The PCS of claim 8 or 9, wherein the fourth portion of the first winding comprises the second outer end turn. (Item 12) 12. The PCS of any one of items 8-11, further comprising vias through the dielectric layer, the vias electrically interconnecting each of the second radial conductors with a corresponding one of the first radial conductors. (Item 13) 13. The PCS of any one of items 8-12, wherein the first winding comprises a first serpentine winding and the second winding comprises a second serpentine winding. (Item 14) 1. A planar composite structure (PCS) for use in an axial flux motor or generator, said PCS comprising: a dielectric layer; a first conductive layer located on a first side of the dielectric layer, the first conductive layer including a first conductive trace that, when energized, forms a first portion of a winding that generates magnetic flux for a first phase of the motor or generator; a second conductive layer located on a second side of the dielectric layer, the second conductive layer including a second conductive trace forming a second portion of the winding; and Equipped with the first portion of the winding is connected in series with the second portion of the winding; The first and second portions of the winding are constructed and arranged so that the same amount of current flows through each of the first and second portions of the winding. (Item 15) The first conductive trace comprises: first radial conductors, each of the first radial conductors extending radially between at least a first radial distance and a second radial distance greater than the first radial distance; a first conductive end turn; and Equipped with each of the first conductive end turns interconnecting a respective pair of the first radial conductors; The second conductive trace comprises: second radial conductors, each of the second radial conductors extending radially between at least the first radial distance and the second radial distance, and each of the second radial conductors electrically connected to a corresponding one of the first radial conductors; a second conductive end turn; Equipped with Item 15. The PCS of item 14, wherein each of the second conductive end turns interconnects a respective pair of the second radial conductors. (Item 16) the first conductive end turn comprises a first inner end turn; the first inner end turn electrically interconnects portions of a first pair of the first radial conductors at the first radial distance; the first portion of the winding includes the first inner end turn; the second conductive end turn comprises a second inner end turn; the second inner end turn electrically interconnects portions of a first pair of the second radial conductors at the first radial distance; Item 16. The PCS of item 15, wherein the second portion of the winding comprises the second inner end turn. (Item 17) the winding further comprises a third portion electrically connected in series between the first portion of the winding and the second portion of the winding; the first conductive end turn further comprises a first outer end turn; the first outer end turn electrically interconnects a portion of one of the first pair of first radial conductors at the second radial distance with a portion of another of the first radial conductors at the second radial distance; Item 17. The PCS of item 16, wherein the third portion of the winding comprises the first outer end turn. (Item 18) Item 18. The PCS of item 17, wherein the first inner end turn, the second inner end turn, and the first outer end turn are arranged such that the first, second, and third portions of the first winding form a serpentine pattern. (Item 19) the winding includes a fourth portion electrically connected in series with the second portion of the winding; the first conductive end turn further comprises a second outer end turn; the second outer end turn electrically interconnects portions of a second pair of the second radial conductors at the second radial distance; Item 19. The PCS of item 17 or item 18, wherein the fourth portion of the winding comprises the second outer end turn. (Item 20) the winding includes a fourth portion electrically connected in series with the second portion of the winding; the second conductive end turn further comprises a second outer end turn; the second outer end turn electrically interconnects a portion of one of the first pair of second radial conductors at the second radial distance with a portion of another of the second radial conductors at the second radial distance; Item 19. The PCS of item 17 or item 18, wherein the fourth portion of the winding comprises the second outer end turn. (Item 21) 21. The PCS of any one of items 15-20, further comprising vias through the dielectric layer, the vias electrically interconnecting each of the second radial conductors with a corresponding one of the first radial conductors. (Item 22) the first conductive layer is included in a first subassembly of the PCS; the second conductive layer is included in a second subassembly of the PCS; the first subassembly includes a third portion of the winding; the third portion of the winding includes the first portion of the winding; a third portion of the winding encircling the first region of the first subassembly at least once; the second subassembly includes a fourth portion of the winding; the fourth portion of the winding includes the second portion of the winding; 17. The PCS of any one of items 14-16, wherein the fourth portion of the winding encircles the second region of the second subassembly at least once. (Item 23) 1. A planar composite structure (PCS) for use in an axial flux motor or generator, said PCS comprising: a first conductive layer comprising a first conductive trace, the first conductive trace including a first radial conductor extending radially from a first radial distance to a second radial distance greater than the first radial distance; a second conductive layer comprising a second conductive trace, the second conductive trace including a second radial conductor extending radially from the first radial distance to the second radial distance; a third conductive layer comprising a third conductive trace, the third conductive trace including a third radial conductor extending radially from the first radial distance to the second radial distance; a fourth conductive layer including a fourth conductive trace, the fourth conductive trace including a fourth radial conductor extending radially from the first radial distance to the second radial distance; Including, the first radial conductors are electrically connected to corresponding ones of the second radial conductors by first blind or buried vias; The PCS, wherein the third radial conductors are electrically connected to corresponding ones of the fourth radial conductors by second blind or buried vias. (Item 24) the first conductive trace further comprises first conductive end turns, each of the first conductive end turns interconnecting a respective pair of the first radial conductors; the second conductive trace further comprises second conductive end turns, each of the second conductive end turns interconnecting a respective pair of the second radial conductors; the third conductive trace further comprises third conductive end turns, each of the third conductive end turns interconnecting a respective pair of the third radial conductors; Item 24. The PCS of item 23, wherein the fourth conductive trace further comprises fourth conductive end turns, each of the fourth conductive end turns interconnecting a respective pair of the fourth radial conductors. (Item 25) the first radial conductor, the second radial conductor, the first conductive end turn, and the second conductive end turn, when energized, establish an electrical path for a first portion of a winding that generates magnetic flux for a first phase of the motor or generator; the third radial conductor, the fourth radial conductor, the third conductive end turn, and the fourth conductive end turn establish an electrical path for a second portion of the winding; Item 25. The PCS of item 24, wherein the first portion of the winding is connected in series with the second portion of the winding. (Item 26) 1. A planar composite structure (PCS) for use in an axial flux motor or generator, the PCS comprising a first subassembly including a first conductive layer, the first conductive layer including a first radial conductor extending radially from a first radial distance to a second radial distance greater than the first radial distance, a first end-turn conductor, and a second end-turn conductor; the first end-turn conductor interconnects a first group of the first radial conductors and forms a first winding for a first phase of the axial flux motor or generator; the second end-turn conductors interconnect a second group of the first radial conductors and form a second winding for a second phase of the axial flux motor or generator; The PCS, wherein the first subassembly includes more second end-turn conductors than first end-turn conductors. (Item 27) a second subassembly, the second subassembly comprising a second conductive layer different from the first conductive layer, the second conductive layer including a second radial conductor, a third end turn conductor, and a fourth end turn conductor; the third end-turn conductor interconnects the first group of the second radial conductors and forms a third winding for a first phase of the axial flux motor or generator; the fourth end-turn conductor interconnects a second group of the second radial conductors and forms a fourth winding for a second phase of the axial flux motor or generator; 27. The PCS of claim 26, wherein the first subassembly includes more third end-turn conductors than fourth end-turn conductors. (Item 28) Item 28. The PCS of item 27, wherein the third winding is connected in series with the first winding and the fourth winding is connected in series with the second winding. (Item 29) 29. The PCS of claim 27 or 28, wherein the number of the first end-turn conductors plus the number of the third end-turn conductors is equal to the number of the second end-turn conductors plus the number of the fourth end-turn conductors. (Item 30) the first end turn conductor comprises a first inner end turn conductor and a first outer end turn conductor; the second end turn conductor comprises a second inner end turn conductor and a second outer end turn conductor; each of the first inner end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the first radial distance; each of the first outer end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the second radial distance; each of the second inner end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the first radial distance; each of the second outer end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the second radial distance; the first subassembly includes a same number of first inner end-turn conductors as second inner end-turn conductors; 30. The PCS of any one of items 26-29, wherein the first subassembly includes more second outer end-turn conductors than first outer end-turn conductors. [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1A illustrates a "layer of turns" of a planar stator having a winding layout such as that described in US Pat. No. 7,109,625 ("the '625 patent").

[0009] [Figure 1B] FIG. 1B illustrates the "link layer" of a planar stator having a winding layout such as that described in the '625 patent.

[0010] [Figure 1C] FIG. 1C illustrates the link layer shown in FIG. 1B over the turn layer shown in FIG. 1A, with hidden lines removed.

[0011] [Figure 2] FIG. 2 shows a view of a selected portion of a stator configuration having a stack of three six-layer subassemblies.

[0012] [Figure 3]FIG. 3 shows radial traces at a single angular position across the 12 conductive layers of a PCS organized in three parallel groups connected by blind or buried vias.

[0013] [Figure 4] FIG. 4 shows an inner end turn of the type described in the '625 patent that is similar to the inner end turn shown in FIG. 1A.

[0014] [Figure 5] 5A and 5B show alternative arrangements of the inner end turns on two respective conductive layers of the PCS.

[0015] [Figure 6] FIG. 6 shows an outer end turn of the type described in the '625 patent that is similar to the outer end turn shown in FIG. 1A.

[0016] [Figure 7] 7A and 7B show alternative arrangements of the outer end turns on two respective conductive layers of the PCS.

[0017] [Figure 8] FIG. 8 shows the inner and outer end turns that interconnect the radial traces and form a single coil of the stator in accordance with the winding layout taught by the '625 patent.

[0018] [Figure 9] FIG. 9 shows the alternating arrangement of inner and outer end turns for a single phase in a plan view of multiple layers.

[0019] [Figure 10A] FIG. 10A shows an enlarged perspective view (in the z-axis) of a subassembly including four conductive layers, with the inner and outer end turns corresponding to selected phases for clarity.

[0020] [Figure 10B] FIG. 10B illustrates the location of the inner and outer end turns for the first phase in the subassembly shown in FIG. 10A.

[0021] [Figure 11A] FIG. 11A illustrates the location of the inner and outer end turns for the second phase in the subassembly shown in FIG. 10A.

[0022] [Figure 11B] FIG. 11B illustrates the location of the inner and outer end turns for the third phase in the subassembly shown in FIG. 10A.

[0023] [Figure 12A] FIG. 12A shows an enlarged perspective view (in the z-axis) of an assembly of three subassemblies, each similar to the subassembly shown in FIG. 10A.

[0024] [Figure 12B] FIG. 12B illustrates the location of the inner and outer end turns for the first phase in the stack of three subassemblies shown in FIG. 12A.

[0025] [Figure 13A] FIG. 13A illustrates the location of the inner and outer end turns for the second phase in the stack of three subassemblies shown in FIG. 12A.

[0026] [Figure 13B] FIG. 13B illustrates the location of the inner and outer end turns for the third phase in the stack of three subassemblies shown in FIG. 12A.

[0027] [Figure 14]FIG. 14 shows an enlarged perspective view (in the z-axis) of an exemplary embodiment of a stator employing serpentine windings such as those shown in FIG. 9, with inner end turns of the type shown in FIGS. 5A and B and outer end turns of the type shown in FIGS. 7A and 7B employed to establish all of the winding connections required for three phases in an assembly including only two conductive layers.

[0028] [Figure 15A] FIG. 15A shows an enlarged perspective view (in the z-axis) of only a portion of the assembly shown in FIG. 14 corresponding to the first phase of the stator.

[0029] [Figure 15B] FIG. 15B shows a portion of the upper conductive layer shown in FIG. 15A that contributes to the winding for the first phase.

[0030] [Figure 15C] FIG. 15C shows a portion of the lower conductive layer shown in FIG. 15A that contributes to the winding for the first phase.

[0031] [Figure 16A] FIG. 16A illustrates how the windings for the second phase can make their way through the assembly shown in FIG. 14, with the portions of the assembly corresponding to the other two phases removed for illustration purposes.

[0032] [Figure 16B] FIG. 16B illustrates how the windings for the third phase can make their way through the assembly shown in FIG. 14, with the portions of the assembly corresponding to the other two phases removed for illustration purposes.

[0033] [Figure 17] 17A and 17B illustrate an example process for forming a multi-layer PCS assembly / subassembly.

[0034] [Figure 18A] FIG. 18A illustrates a system in which a PCS such as those described herein is employed as a stator in an axial flux motor or generator.

[0035] [Figure 18B] FIG. 18B illustrates an expanded view of the system shown in FIG. 18A. DETAILED DESCRIPTION OF THE INVENTION

[0036] For example, a planar composite structure (PCS) that may be used as a stator in an axial flux motor or generator can be constructed by forming multiple layers of conductive traces (conductive layers) on one or more layers of non-conductive dielectric material (dielectric layers). Examples of this type of stator are described in U.S. Pat. No. 7,109,625 (the "'625 patent"), U.S. Pat. No. 9,673,688, U.S. Pat. No. 9,673,684, and U.S. Pat. No. 9,800,109 (the entire contents of each of which are incorporated herein by reference).

[0037] 1A-C show plan views of two conductive layers of a planar stator having a winding layout such as that described in the '625 patent. Together, the layers shown establish the inner and outer "end turns" required for a single phase. FIG. 1A shows a single "turn layer" L1 with inner end turns 102a and outer end turns 106 that arrange radial traces 104 within the coil, each associated with a pole pair. On this 16-pole stator, there are eight such coils. In the example shown, the coils spiral so that the end of each coil cannot be routed to the start of a subsequent coil on the same layer. This routing difficulty is explained in more detail below in connection with FIG. 8. FIG. 1B shows a "link layer" L2, including links 108, which serve to connect subsequent coils without interference with turn layer L1. Each of the radial traces 104 on layer L1 is connected to a corresponding (and parallel) radial trace 104 on layer L2, for example, using vias (not shown). Link layer L2 also includes an inner end turn 102b that overlaps with an inner end turn 102a in turn layer L1. FIG. 1C shows link layer L2 on top of turn layer L1, with hidden lines removed. As can be seen, in this configuration, the outer end turns 106 and links 108 occupy some of the same space on the outer radius of the stator. Therefore, a complete three-phase stator with a winding layout such as that taught by the '625 patent requires a minimum of six conductive layers (i.e., three phases × two layers per phase). A balanced stator employing such a winding layout therefore requires a number of conductive layers that is a multiple of six. As used herein, a "balanced stator" refers to a stator in which the electrical load characteristics (in motor mode) or power supply characteristics (in generator mode) of each phase are equal up to a certain electrical phase angle.

[0038] With respect to Figures 1A-C, it should be understood that certain details of the depicted designs, e.g., specific structures and / or configurations for thermal management and loss reduction (such as those disclosed in U.S. Patent Nos. 9,673,684 and 9,800,109), are not disclosed in the '625 patent. Figures 1A-C therefore illustrate only the relative positions of the radial traces, inner end turns, outer end turns, and links as taught by the '625 patent, rather than the specific structures or configurations that the '625 patent discloses for those elements.

[0039] Stators have been designed in which multiple three-phase balanced stator subassemblies (each with six conductive layers) are stacked and connected in parallel on the same planar composite structure (PCS). Such a design can increase the current capacity and efficiency of each phase of the stator, for example, because the current for each phase can be carried along parallel paths within each subassembly. FIG. 2 shows a drawing of a selected portion of a stator configuration with three six-layer subassemblies stacked in this manner, focusing on a single radial trace 204 as it is connected in parallel across 18 conductive layers (using vias 210). On the last layer, L18, two adjacent radial traces 204a, 204b are also shown as a visual guide. The parallel arrangement of radial traces 204 in the active area, connected by through vias 210, provides an opportunity to arrange inner and outer windings and links (as in FIGS. 1A-C) across multiple conductive layers. However, because these 18 radial traces are parallel, they can only contribute to a single winding structure.

[0040] Figure 3 is similar to Figure 2, but shows a structure related to the present disclosure. In particular, Figure 3 shows radial traces 304 at a single angular position across the 12 conductive layers of the PCS. As shown, each radial trace 304 extends from a first radial distance R1 to a second radial distance R2 that is greater than the first radial distance R1.In this case, the radial traces 304 are organized in three parallel groups 312a, 312b, 312c connected by blind or buried vias 310. For manufacturing reasons, it is most convenient to have a multiple of two conductive layers for each of these groups. Unlike stators constructed in accordance with the '625 patent, each parallel group 312a, 312b, 312c of radial traces 304 is connected in series, thus allowing for a higher number of windings for each coil of the stator. The number of windings for the structure shown in FIG. 3, which includes three groups of radial traces connected in parallel, can be, for example, three times higher than the number of windings for the structure shown in FIG. 2. Examples of stator implementations in which multiple parallel-connected groups of radial traces are connected in series in such a manner are described below in connection with FIGS. 12A, 12B, 13A, and 13B.

[0041] Figure 4 shows a plurality of radial traces 404, each extending from a first radial distance R1 to a second radial distance R2 greater than the first radial distance R1; and 1A shows inner end turns 402 of the type described in the '625 patent, which are similar to the inner end turns 102 shown in FIG. 1A. These inner end turns 402, together with outer end turns 606 (shown in FIG. 6), form all of the connections between the respective radial traces 404 needed to establish the three windings per pole pair of a single phase. Thus, according to the teachings of the '625 patent, one conductive layer containing inner end turns 402 like those shown in FIG. 4 and outer end turns 606 like those shown in FIG. 6 (described below) is needed to connect a single phase. For a three-phase board constructed according to this design, a minimum of three such conductive layers is needed.

[0042] 5A and 5B show alternative arrangements of inner end turns 502 on two respective conductive layers L3 and L4. It should be understood that the layer numbers used herein, e.g., “L3,” are provided solely to facilitate identification of the various layers being described and are not intended to imply an order in which the various layers are positioned. In the illustrated arrangement, when the radial traces 404 on layer L3 are connected in parallel with corresponding (and parallel) radial traces 404 on layer L4, e.g., using vias (not shown in FIGS. 5A and 5B ) similar to vias 310 shown in FIG. 3 , the inner end turn connections for all of the radial traces 404 shown in FIGS. 5A and 5B can be established on only two conductive layers. As described in more detail below, such an arrangement allows inner end turns 502 for multiple phases to be provided on the same conductive layer, and also allows inner end turns 502 for the same phase to be distributed among multiple conductive layers. This is in contrast to the configuration of FIG. 4, in which the inner end turns 402 for only a single phase are provided on a given layer, and the inner end turns 402 for a given phase are all contained on the same conductive layer.

[0043] Additionally, as discussed in more detail below, in some implementations, either or both of layers L3 and L4 may additionally include outer end turns, which may be arranged similarly to, for example, outer end turns 606 illustrated in FIG. 6 (described below). Illustrative examples of this type are described below in conjunction with FIGS. 10A, 10B, 11A, 11B, 12A, 12B, 13A, and 13B. Alternatively, the outer end turns provided on layers L3 and L4 may be identical to or similar to outer end turns 706 described below in conjunction with FIGS. 7A and 7B. Illustrative examples of the latter type are described below in conjunction with FIGS. 14, 15A, 15B, 15C, 16A, and 16B. Other configurations of outer end turns on either or both layers L3 and L4, or even configurations in which all outer end turns are included on layers other than layers L3 and L4, are possible and contemplated.

[0044] Two complementary sets of inner end turns 502 are shown in Figures 5A and 5B, with a first set of inner end turns 502a, 502b, 502c, 502d, 502e, and 502f depicted on layer L3 in Figure 5A and a second set of inner end turns 502g, 502h, 502i, 502j, 502k, and 502l depicted on layer L4 in Figure 5B. By comparing these complementary connections and understanding that inner end turns 502 for multiple phases may be provided on the same conductive layer and that inner end turns 502 for a given phase may be distributed among multiple conductive layers, it becomes apparent that all of the inner end turn connections required for a three-phase stator can be achieved within only the two layers L3 and L4 shown. For example, a first phase can be supported by inner end turns 502a and 502d on layer L3 of Figure 5A and inner end turns 502h and 502k on layer L4 of Figure 5B, a second phase can be supported by inner end turns 502b and 502e on layer L3 of Figure 5A and inner end turns 502i and 502l on layer L4 of Figure 5B, and a third phase can be supported by inner end turns 502c and 502f on layer L3 of Figure 5A and inner end turns 502g and 502j on layer L4 of Figure 5B. In such an implementation, the inner end turns 502 for each phase consume one-third of layer L3 and one-third of layer L4, so that the inner end turns 502 for each phase consume a total of two-thirds of the layer value of the locations on layers L3 and L4. Moreover, in the example implementation shown, a minimum of two conductive layers are required to form a complete inner end-turn connection for all three phases, and the number of conductive layers should be a multiple of two in order for the stator to be balanced with respect to the inner end-turns.

[0045] Further, in the exemplary configuration shown in Figures 5A and B, there are a total of 12 end turn groups 502a-502l available to establish the respective poles, and therefore, each phase of a three-phase stator employing such a configuration should preferably have four poles. In other words, for a closely packed inner end turn configuration such as that shown in Figures 5A and B, the following equation is preferably satisfied for a three-phase stator (where "k" is an integer): 4 * k=3*pole

[0046] Figure 6 shows outer end turns 606 of the type described in the '625 patent, which are similar to the outer end turns 106 shown in Figure 1A. These outer end turns 606, together with the inner end turns 402 (shown in Figure 4), form all of the connections between the respective radial traces 404 needed to establish the three windings per pole pair of a single phase. Thus, according to the teachings of the '625 patent, one layer containing outer end turns 606 like those shown in Figure 6 and inner end turns 402 like those shown in Figure 4 is needed to connect a single phase. For a three-phase board constructed according to this design, a minimum of three such conductive layers is needed.

[0047] Similar to FIGS. 5A and 5B, FIGS. 7A and 7B show alternative arrangements of outer end turns 706 on two respective conductive layers L5 and L6. In the illustrated arrangement, when the radial traces 404 on layer L5 are connected in parallel with corresponding (and parallel) radial traces 404 on layer L6, for example, using vias (not shown in FIGS. 7A and 7B) similar to vias 310 shown in FIG. 3, the outer end turn connections for all of the radial traces 404 shown in FIGS. 7A and 7B can be established on only two layers. As explained in more detail below, such an arrangement allows outer end turns 706 for multiple phases to be provided on the same conductive layer, and also allows outer end turns 706 for the same phase to be distributed among multiple conductive layers. This contrasts with the configuration of FIG. 6, in which outer end turns 606 for only a single phase are provided on a given conductive layer, and the outer end turns 606 for a given phase are all contained on the same conductive layer.

[0048] Additionally, as discussed in more detail below, in some implementations, either or both of layers L5 and L6 may additionally include inner end turns, which may be arranged similarly to, for example, inner end turns 402 illustrated in FIG. 4. Alternatively, the inner end turns provided on layers L5 and L6 may be identical to or similar to inner end turns 502 described above in connection with FIGS. 5A and 5B. Illustrative examples of the latter type are described below in connection with FIGS. 14, 15A, 15B, 15C, 16A, and 16B. Other configurations of inner end turns on either or both layers L5 and L6, or even configurations in which all inner end turns are included on layers other than layers L5 and L6, are possible and contemplated.

[0049] It should be understood that whatever the implementation, some mechanism will need to be used to get current to each phase in some way. In the example illustrated in Figures 7A and 7B, this is accomplished by configuring outer end turns 706b, 706c, and 706h differently from the other outer end turns to establish inputs 708a, 708b, and 708c to their respective winding circuits. In other implementations, current may additionally or alternatively be introduced to one or more of the phases in some other manner, such as by directly connecting wires from one or more other conductive layers to pads inside outer end turns 706 using vias / solder pads / pressure contacts or pins to dedicated connection layers, or another similar technique.

[0050] Further, it should be understood that in some implementations, current may additionally or alternatively be fed to each phase from an inner region of the stator, with one or more inner end turn groups 402, 502, such as those shown in FIGS. 4 and 5, being configured differently from the other inner end turn groups to allow inputs similar to inputs 708a, 708b, and / or 708c, but instead being located within the inner region of the stator. Moreover, in some implementations, rather than having a shaft passing through a central region of the stator, the rotor may instead operate “outside” the stator; for example, an annular or tubular rotor structure may surround and rotate about the stator. For example, in certain embodiments, such an implementation in which current is fed to each phase from an inner region of the stator may make sense.

[0051] Two complementary pairs of outer end turns 706 are shown in FIGS. 7A and 7B. 706a, 706b, 706c, 706d, 706e, and 706f The first set is depicted on layer L5 of FIG. 7A, and includes the outer end turns. 706g, 706h, 706i, 706j, 706k, and 706lA second set of outer end turns 706 is depicted on layer L6 in Figure 7B. By comparing these complementary connections and understanding that outer end turns 706 for multiple phases may be provided on the same conductive layer, and that the outer end turns 706 for a given phase may be distributed among multiple conductive layers, it becomes apparent that all of the outer end turn connections required for a three-phase stator may be achieved within only the two layers L5 and L6 shown. For example, a first phase can be supported by outer end turns 706a and 706d on layer L5 in Figure 7A and outer end turns 706h and 706k on layer L6 in Figure 7B, a second phase can be supported by outer end turns 706b and 706e on layer L5 in Figure 7A and outer end turns 706i and 706l on layer L6 in Figure 7B, and a third phase can be supported by outer end turns 706c and 706f on layer L5 in Figure 7A and outer end turns 706g and 706j on layer L6 in Figure 7B. In such an implementation, the outer end turns 706 for each phase consume one-third of layer L5 and one-third of layer L6, so that the outer end turns 706 for each phase consume a total of two-thirds of the layer value of the locations on layers L5 and L6. Moreover, in the example implementation shown, a minimum of two conductive layers are required to form a complete outer end turn connection for all three phases, and in order for the stator to be balanced with respect to the outer end turns, the number of conductive layers should be a multiple of two.

[0052] FIG. 8 shows inner end turns 802 and outer end turns 806 that interconnect radial traces 804 and form a single coil of the stator according to the winding layout taught by the '625 patent. The illustrated coil can be seen to either start at point 808 and "spiral inward" to point 810, or start at point 810 and "spiral outward" to point 808. Note that in this configuration, there are four inner end turns 802 but only three outer end turns 806. The "missing" outer end turn 806 cannot be routed on the same layer as the other turns because it must establish a connection from the inside of a spiral (e.g., point 810) to the outside of the next spiral (or vice versa). This type of connection only encircles the center point of the stator once as it progresses around the periphery of the stator.

[0053] FIG. 9 shows an alternating arrangement of inner and outer end turns for a single phase in a plan view of multiple conductive layers. Three windings are provided in the layer shown. In some implementations, inner end turns 502 such as those shown in FIGS. 5A and 5B may be employed, with the inner end turns 502 distributed across two (or more) conductive layers. In some implementations, for example, the inner end turns illustrated in FIG. 9 may include two groups of inner end turns 502 from one layer (e.g., inner end turns 502b and 502e on layer L3 shown in FIG. 5A) and two groups of inner end turns 502 from another layer (e.g., inner end turns 502i and 502l on layer L4 shown in FIG. 5B). As discussed above in connection with FIGS. 5A and 5B, the use of inner end turns 502 from two or more conductive layers can enable the formation of a complete set of inner end turn connections for a single phase. Alternatively, in some implementations, some or all of the inner end turns illustrated in FIG. 9 may be of the type shown in FIG. 4, i.e., inner end turn 402, and may be disposed within a common conductive layer.

[0054] In some implementations, some or all of the outer end turns illustrated in FIG. 9 may be of the type shown in FIG. 6 , i.e., like outer end turns 606, and may be located in a common conductive layer. Alternatively, some or all of the illustrated outer end turns may be of the type shown in FIG. 7 , i.e., like outer end turns 706, and may be distributed across two (or more) conductive layers. In some implementations, for example, the outer end turns illustrated in FIG. 9 may include two groups of outer end turns 706 from one conductive layer (e.g., outer end turns 706a and 706d on layer L5 shown in FIG. 7A ) and two groups of outer end turns 706 from another conductive layer (e.g., outer end turns 706h and 706k on layer L6 shown in FIG. 7B ). As discussed above in connection with FIGS. 7A and 7B , the use of outer end turns 706 from two or more conductive layers can enable the formation of a complete set of outer end turn connections for a single phase.

[0055] Whatever the implementation, it should be understood that, in contrast to FIG. 8 , for the majority of end turn groups, the number of turns in a given group of outer end turns 606, 706 is equal to the number of turns in an adjacent group of inner end turns 402, 502, and vice versa. The connection from the upper right terminal 902, tracing the radial trace 404, the inner end turns 402, 502, and the outer end turns 606, 706 forms a serpentine pattern that can be routed within a single conductive layer. In the implementation shown in FIG. 8 , by contrast, only the unconnected windings can be routed within a single conductive layer. As shown in FIG. 9 , the serpentine pattern starting at terminal 902 and ending at terminal 904 encircles the stator center point 906 three times (or three turns).

[0056] Figures 10A, 10B, 11A, 11B, 12A, 12B, 13A, and 13B illustrate an exemplary embodiment of a stator employing serpentine windings such as those shown in Figure 9, in which inner end turns 502 of the type shown in Figures 5A and B and outer end turns 606 of the type shown in Figure 6 are employed to establish winding connections for one or more subassemblies, each including four conductive layers. Features of a single such subassembly S1 are illustrated in Figures 10A, 10B, 11A, and 11B, and features of a stacked set of three such subassemblies S1, S2, and S3 are illustrated in Figures 12A, 12B, 13A, and 13B. In the example shown in these figures, for each subassembly S1, S2, and S3 shown, each of the radial connectors 404 on a given conductive layer of that subassembly is connected to a corresponding (and parallel) one of the radial connectors 404 in the other conductive layer of that same subassembly using vias 310, in the manner shown in Figure 3. Illustrative techniques for forming multi-layer PCS assemblies / subassemblies such as those shown are described below in connection with Figures 17A and 17B.

[0057] FIG. 10A shows an enlarged perspective view (in the z-axis) of a subassembly S1 having four conductive layers, with inner end turns 502b, 502e, 502i, 502l and outer end turn 606 corresponding to a selected phase for clarity. The locations of additional inner end turns 502 and outer end turns 606 that may be incorporated into the structure of FIG. 10A to establish the other two phases of a three-phase stator are illustrated in FIGS. 11A-11B below. FIG. 10B is similar to FIG. 10A , but for illustration purposes, additional portions of subassembly S1 corresponding to the other two phases have been removed. FIG. 10B therefore illustrates how the windings for a single phase of a three-phase stator can make their way through a subassembly S1 having four conductive layers.

[0058] 10B, FIGS. 11A-11B illustrate how the windings of the two remaining phases may make their way through subassembly S1 shown in FIG. 10A, with the portions of the subassembly corresponding to the other two phases removed for purposes of illustration. Thus, FIG. 10B illustrates the location of inner end turns 502b, 502e, 502i, 502l and outer end turn 606 for the first phase within subassembly S1, FIG. 11A illustrates the location of inner end turns 502a, 502d, 502h, 502k and outer end turn 606 for the second phase within subassembly S1, and FIG. 11B illustrates the location of inner end turns 502c, 502f, 502g, 502i for the third phase within subassembly S1. j and the position of the outer end turn 606 is illustrated.

[0059] The inner end turns 502b, 502e, 502i, and 502l for the first phase illustrated in Figures 10A and 10B appear with a multiplicity of 2 for the four conductive layers, with inner end turns 502b and 502e appearing on two of the four illustrated layers and inner end turns 502i and 502l appearing on the remaining two layers. The same is true for the inner end turns 502 for the other two phases illustrated in Figures 11A and 11B. That is, for the second phase illustrated in FIG. 11A, inner end turns 502a, 502d, 502h, 502k occur with a multiplicity of 2 for four layers, inner end turns 502a and 502d occur on two of the four illustrated layers, and inner end turns 502h and 502k occur on the remaining two layers; and for the third phase illustrated in FIG. 11B, inner end turns 502c, 502f, 502g, 502k occur on two of the four illustrated layers. j appears on four layers with a multiplicity of 2, with inner end turns 502c and 502f appearing on two of the four illustrated layers, and inner end turns 502g and 502h appearing on four illustrated layers. jappears on the remaining two layers. Thus, for all three phases of subassembly S1 shown in Figures 10A, 10B, 11A, and 11B, inner end turns 502 appear with a multiplicity of two for four conductive layers, which is balanced (equal for each phase) because subassembly S1 has a number of conductive layers that is a multiple of two.

[0060] For the particular phase shown in FIGS. 10A and 10B, i.e., the first phase, the outer end turns 606 also occur with a multiplicity of two with respect to the four layers shown. For that phase, the outer end turns 606 occupy two of the four conductive layers. The outer end turns 606 for the other two phases (shown in FIGS. 11A and 11B) are on the other two conductive layers, but without redundancy. That is, the outer end turns 606 for the second phase (shown in FIG. 11A) occur on only a single conductive layer, as do the outer end turns 606 for the third phase (shown in FIG. 11B). Thus, the subassembly S1 shown in FIGS. 10A, 10B, 11A, and 11B has all the required connections for a three-phase stator, but is not balanced due to the unequal redundancy of the outer end turns 606 with respect to the phases.

[0061] FIG. 12A shows an enlarged perspective view (in the z-axis) of an assembly of three subassemblies S1, S2, and S3, each similar to the subassembly shown in FIG. 10A. In some embodiments, two or more such respective subassemblies may be stacked together to form a single PCS. As in FIG. 10A, FIG. 12A shows, for clarity, inner end turns 502 and outer end turns 606 associated with only one of the three phases. The locations of additional inner end turns 502 and outer end turns 606 that may be incorporated into the structure of FIG. 12A to establish the other two phases of a three-phase stator are illustrated in FIGS. 13A-13B below.

[0062] FIG. 12B is similar to FIG. 12A , but for illustration purposes, additional portions of subassemblies S1, S2, and S3 corresponding to the other two phases have been removed. FIG. 12B thus illustrates how the windings for a single phase of a three-phase stator can make their way through a stacked set of three subassemblies S1, S2, and S3, each having four conductive layers. The subassemblies S1, S2, and S3 can be electrically connected in either parallel or series by through vias 1202 a, 1202 b, 1202 c, 1204 a, 1204 b, 1204 c, 1206 a, 1206 b, and 1206 c. In the example shown, the windings of the three subassemblies S1, S2, and S3 are connected in series, so that the number of windings for each phase of the entire assembly is three times greater than the number of windings of any one of the individual subassemblies S1, S2, and S3.

[0063] The manner in which current may flow through or between the windings of subassemblies S1, S2, and S3 for the phase illustrated in FIG. 12B will now be described. Although not individually described, it should be understood that similar paths may be followed for the windings of the other two phases (shown in FIGS. 13A and 13B, described below), although using different groups of through vias 1202, 1204, and 1206. For the phase illustrated in FIG. 12B, current may flow from through via 1202b into the winding of subassembly S1. Current may then exit the winding of subassembly S1 via conductive trace 1208. Current from conductive trace 1208 may flow through through via 1204b to conductive trace 1210, where it may enter the winding of subassembly S2. Current may then exit the winding of subassembly S2 via conductive traces 1212a and 1212b. Current from conductive traces 1212a, 1212b may then flow through through via 1206b to conductive traces 1214a and 1214b, where it may enter the winding of subassembly S3. The current may then exit the winding of subassembly S3 and flow to the neutral conductor, along with current from the other two phases (shown in FIGS. 13A and 13B).

[0064] Similar to FIG. 12B, FIGS. 13A-13B illustrate how the windings of the two remaining phases can make their way through the three subassemblies S1, S2, and S3 shown in FIG. 12A, with the portions of the subassemblies corresponding to the other two phases removed for illustration purposes. Thus, FIG. 12B illustrates the locations of inner end turns 502b, 502e, 502i, and 502l, and outer end turn 606, for a first phase in a stack of three subassemblies S1, S2, and S3; FIG. 13A illustrates the locations of inner end turns 502a, 502d, 502h, and 502k, and outer end turn 606, for a second phase in a stack of three subassemblies S1, S2, and S3; and FIG. 13B illustrates the locations of inner end turns 502c, 502f, 502g, and 502k, for a third phase in a stack of three subassemblies S1, S2, and S3.j , and the position of the outer end turn 606 are illustrated.

[0065] Each subassembly S1, S2, and S3 has four conductive layers, as in FIG. 10A, but differs in phase with a multiplicity of two outer end turns 606 within each assembly. Thus, for the phase illustrated in FIGS. 12A and 12B, the top subassembly S1 has two parallel layers of outer end turns 606, while the other two subassemblies S2 and S3 do not; and for the phase illustrated in FIG. 13A, the bottom subassembly S3 has two parallel layers of outer end turns 606, while the other two subassemblies S 1 and S 2 13B, the central subassembly S2 has two parallel layers of outer end turns 606, while the other two subassemblies S1 and S3 do not. Thus, the stacked assembly shown by the combination of FIGS. 12A, 12B, 13A, and 13B is arranged so that each of the three phases has the same number of parallel and series connected layers of outer windings 606, in addition to having the same number of parallel and series connected layers of inner end turns 502, and thus the entire assembly is balanced.

[0066] Figures 14, 15A, 15B, 15C, 16A, and 16B illustrate an exemplary embodiment of a stator employing serpentine windings such as those shown in Figure 9, and in which inner end turns 502 of the type shown in Figures 5A and B and outer end turns 706 of the type shown in Figures 7A and 7B are employed to establish all of the winding connections required for three phases in an assembly including only two conductive layers. In the example shown in these figures, each of the radial connectors 404 on the upper conductive layer is connected to a corresponding (and parallel) radial connector 404 in the lower conductive layer using vias 1410 similar to vias 310 shown in Figure 3.

[0067] FIG. 15A shows an enlarged perspective view (in the z-axis) of only a portion of the assembly shown in FIG. 14 corresponding to the first phase of the stator. As shown, the first phase may employ inner end turns 502b, 502e, 502i, and 502l shown in FIGS. 5A and 5B and outer end turns 706a, 706d, 706h, and 706k shown in FIGS. 7A and 7B. FIG. 15A therefore illustrates how the windings for a single phase of a three-phase stator can make their way through the assembly shown in FIG. 14. FIGS. 15B and 15C show portions of the upper and lower conductive layers shown in FIG. 15A that contribute to the windings for the first phase, respectively.

[0068] Similar to FIG. 15A, FIGS. 16A and 16B illustrate how the windings for the two remaining phases can make their way through the assembly shown in FIG. 14, with the portions of the assembly corresponding to the other two phases removed for illustration purposes. As shown in FIG. 16A, the second phase can employ inner end turns 502a, 502d, 502h, and 502k shown in FIGS. 5A and 5B and outer end turns 706c, 706f, 706g, and 706j shown in FIGS. 7A and 7B. As shown in FIG. 16B, the third phase can employ inner end turns 502c, 502f, 502g, and 706j shown in FIGS. 5A and 5B. j , and outer end turns 706b, 706e, 706i, and 706l shown in Figures 7A and 7B may be employed.

[0069] The two conductive layer implementation shown in Figures 14, 15A, 15B, 16A, and 16B represents a practical limit for reducing the number of layers required for a complete three-phase stator. However, it should be understood that for such a configuration, some mechanism would be required to establish an electrical connection from the drive circuit (not shown) to a location inside the serpentine winding for each phase. For example, with reference to Figure 15A, an electrical connection is provided through vias 1410 to allow the drive circuit to establish a complete circuit for the first phase. b(or another conductor). An electrical connection to the other end of the meander winding for the first phase can be established using through via 1402b shown in FIG. 15A. Similarly, with reference to FIGS. 16A and 16B, electrical connections can be made to vias 1410 to allow the drive circuit to establish a complete circuit for the second and third phases, respectively. c and 1410 a (or other conductors) would need to be made from the drive circuitry. Electrical connections to the other ends of the meander windings for the second and third phases can be established using through vias 1402c and 1402a shown in Figures 16A and 16B, respectively.

[0070] Such electrical connections can be established using any of several mechanisms, including vias / solder pads / pressure contacts or pins to a dedicated connection layer, directly connecting wires to pads on the inside of the outer end turns, or another similar technique. Assuming no additional layers are required to provide the electrical connections, the greatest advantage of a two-conductive layer approach such as that illustrated in FIGS. 14, 15A, 15B, 15C, 16A, and 16B is that the number of windings per layer can be increased by a factor of three over configurations such as those described in the '625 patent or by a factor of two over the configurations described above in connection with FIGS. 10A, 10B, 11A, 11B, 12A, 12B, 13A, and 13B. This advantage is diminished if additional layers are required, for example, to build a complete stator with neutral connections and terminals outside the outer end turn radius. Additionally, high density outer end turns can strongly impact the ability to utilize thermal features directly connected to the active area.

[0071] Although not shown in the drawings, it should be understood that it is also possible to stack two or more assemblies similar to those shown in FIGS. 14, 15A, 15B, 15C, 16A, and 16B and connect the windings of those assemblies together in either parallel or series. In some implementations, for example, via 1410a shown in FIG. 15A may be connected to the “input” of a serpentine winding of another similar assembly having two conductive layers, e.g., using one of the connection techniques described in the preceding paragraph, thus establishing a series connection to the additional winding for the first phase. In some embodiments, such a serpentine winding in the second assembly may, for example, travel a counterclockwise serpentine path similar to the first assembly, but instead wind “outward” toward the outermost outer end turn 706. Additional electrical connections may similarly be established from the outermost end turns of the second assembly to the input of yet another serpentine winding on yet another assembly having only two conductive layers, with that additional serpentine winding traveling, for example, a counterclockwise serpentine path similar to the second assembly, but again wound "in," similar to the configuration of FIG. 15A. Such a technique of winding "in" and then "out" on each serially connected layer may be repeated any number of times, continuing to increase the number of windings in each phase. In some embodiments, two or more such respective assemblies may be stacked together to form a single planar composite structure (PCS).

[0072] 17A and 17B illustrate an example of a process for forming a multi-layer PCS assembly / subassembly 1700. In the example shown, the PCS assembly / subassembly 1700 includes four conductive layers CL1, CL2, CL3, and CL4 and three non-conductive dielectric layers DL1, DL2, and DL3. However, it should be understood that the described techniques may additionally or alternatively be used to form PCS subassemblies and / or subassemblies with different numbers of layers.

[0073] In some embodiments, two or more dielectric layers DL1, DL2, DL3 may be interleaved and stacked together with multiple conductive layers CL1, CL2, CL3, CL4. The pattern of conductive traces on each conductive layer CL1, CL2, CL3, CL4 may be arranged to form conductors for one or more circuit elements (e.g., portions of a stator winding) and may be formed of a conductive material such as copper. Each conductive layer CL1, CL2, CL3, CL4 may be mechanically supported by at least one dielectric layer DL1, DL2, DL3. The dielectric layer may be formed of a non-conductive material such as fiberglass. Each dielectric layer DL1, DL2, DL3 may thus electrically insulate each pair of conductive layers CL1, CL2, CL3, CL4.

[0074] The conductor patterns of each conductive layer CL1, CL2, CL3, and CL4 can be produced by various methods, including, but not limited to, etching, stamping, spraying, cutting, or machining. In some implementations, for example, the conductor patterns can be chemically etched into both sides of multiple double-sided circuit boards, each of which includes one sheet of fiberglass (e.g., dielectric layer DL1 or DL3 in FIG. 17A ) sandwiched between two sheets of copper (e.g., CL1 and CL2, or CL3 and CL4 in FIG. 17A ). Multiple double-sided circuit boards thus formed can then be stacked together, with a dielectric (e.g., fiberglass) sheet (e.g., dielectric layer DL2 in FIG. 17A ) sandwiched between each pair. The stacked double-sided circuit boards and fiberglass sheets can then be laminated together using heat and pressure to form a multiple-plate array such as the one shown in FIG. 17B . As described, the resulting PCS can be used, for example, as a stator for an axial-flux motor or generator.

[0075] In some embodiments, PCSs of the type described above may employ copper sheets that are thicker than those used in most commonly produced circuit boards. In some implementations, for example, the copper sheets may have thicknesses ranging from 0.004 inches to 0.007 inches. Holes 1702 may be drilled in precise locations through one or more (or all) of the multiple circuit boards of PCS 1700, and the inner walls of the holes may be plated with a conductive material such as copper. The plated holes, also known as vias (e.g., blind or buried vias 310 shown in FIG. 3 or through vias 1202a, 1202b, 1202c, 1204a, 1204b, 1204c, 1206a, 1206b, and 1206c shown in FIG. 12A), may serve as interlayer conductors that electrically interconnect conductive traces on different conductive layers of the PCS. However, it should be understood that other types of interlayer conductors may additionally or alternatively be employed, including, but not limited to, holes filled with conductive material, metal pins, crimp points, spot welds, or wires. Various conductors on different layers of the PCS may be connected together in series and / or parallel by such vias or other interlayer conductors.

[0076] As shown in FIG. 17B, PCS 1700 may additionally include a central bore 1704 for accommodating the shaft of a rotor of an axial flux motor or generator, as described below.

[0077] The assemblies and / or subassemblies described herein may be employed in any known or future-developed motor or generator, including the axial flux motor / generator described in the '625 patent, and the motors and generators described in U.S. Pat. Nos. 9,673,688, 9,673,684, and / or 9,800,109 (the entire contents of which are incorporated by reference above).

[0078] FIG. 18A illustrates rotor components 1804a and 1804b, a shaft 1808, Screw 1802 andFIG. 18A shows an example of a system 1800 employing a planar compound stator 1810 in assembly with wires 1814 and a controller 1812. A close-up view showing these components and the means for their assembly is shown in FIG. 18B. The magnetic pole pattern in the permanently magnetized portions 1806a, 1806b of the rotor assembly is also apparent in the close-up view of FIG. 18B. FIG. 18A is an example of an embodiment in which the electrical connections 1814 are made at the outer radius of the PCS 1810 and the stator is mounted to a frame or casing at the outer periphery. Another useful configuration, i.e., an "outrunner" configuration, involves mounting the stator at the inner radius, making the electrical connections 1814 at that inner radius, and replacing the shaft 1808 with an annular ring that separates the rotor halves. It is also possible to configure the system with only one magnet, i.e., either 1806a or 1806b, or to insert multiple stators between consecutive magnet assemblies. Wires 1814 may also carry information regarding the rotor's position based on readings from Hall-effect or similar sensors mounted on the stator. Although not shown, an encoder attached to shaft 1808 may provide position information to controller 1812.

[0079] 18A and 18B can function as either a motor or a generator, depending on the operation of the controller 1812 and components connected to the shaft 1808. As a motor system, the controller 1812 controls the current in the stator 1810 to generate current through the magnets 1808 connected to the shaft 1808. 6 a, 180 6The switches are operated to generate a torque about the shaft 1808 due to the magnetic flux in the gap resulting from a. Depending on the design of the controller 1812, the magnetic flux in the gap and / or rotor position may be measured or estimated, and the switches operated to achieve a torque output at the shaft 1808. As a generator system, a source of mechanical rotating power connected to the shaft 1808 generates a voltage waveform at the stator terminals 1812. These voltages can either be applied directly to a load, or they can be rectified using a three-phase (or polyphase) rectifier within the controller 1812. The rectifier implementation 1812 can be "self-commutated" using diodes in generator mode, or the rectifier implementation 1812 can be configured using controlled switches in the motor controller, but operated such that the shaft torque opposes the torque provided by the mechanical source and mechanical energy is converted to electrical energy. Thus, the same configuration within 18A can function as both a generator and a motor, depending on how the controller 1812 is operated. Additionally, the controller 1812 may include filter components that mitigate switching effects, reduce EMI / RFI from the wires 1814, reduce losses, and provide additional flexibility in the power supplied to or delivered from the controller.

[0080] Having thus described several aspects of at least one embodiment of this invention, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0081] Various aspects of the present invention may be used alone or in combination, or in various arrangements not specifically discussed in the above-described embodiments, and therefore this application is not limited to the details and arrangements of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0082] The present invention may also be embodied as a method, examples of which are provided. The acts performed as part of the method may be ordered in any suitable manner. Thus, although acts are shown as sequential in the illustrative embodiments, embodiments may be constructed in which acts are performed in a different order than illustrated, which may include performing certain acts simultaneously.

[0083] The use of ordinal terms such as "first," "second," "third," etc. in the claims to modify claim elements does not in itself imply any priority, precedence, or ordering of one claim element with respect to another, or the chronological order in which method actions are performed, but merely distinguishes one claimed element having a certain name from another element having the same name (but for the absence of the ordinal term), and is used as a marker to distinguish between claim elements.

[0084] The phraseology and terminology used herein is also for purposes of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof, as used herein, is meant to encompass the items listed thereafter, equivalents thereof, and additional items.

Claims

1. 1. A planar composite structure (PCS) as a stator for use in an axial flux motor or generator, said PCS comprising: a first dielectric layer; a first conductive layer on a first side of the first dielectric layer, the first conductive layer comprising a first conductive trace, the first conductive trace comprising: a first radial conductor extending radially from a first radial distance to a second radial distance greater than the first radial distance; first conductive end turns, each of the first conductive end turns interconnecting a respective pair of the first radial conductors; a first conductive layer comprising: a second conductive layer on a second side of the first dielectric layer, the second conductive layer comprising a second conductive trace, the second conductive trace comprising: a second radial conductor extending radially from the first radial distance to the second radial distance; second conductive end turns, each of the second conductive end turns interconnecting a respective pair of the second radial conductors; a second conductive layer comprising: first blind or buried vias through the first dielectric layer, each of the first radial conductors being electrically connected to a corresponding one of the second radial conductors through at least one respective first blind or buried via; a second dielectric layer; and a third conductive layer on the first side of the second dielectric layer, the third conductive layer comprising a third conductive trace, the third conductive trace comprising: a third radial conductor extending radially from the first radial distance to the second radial distance; third conductive end turns, each of the third conductive end turns interconnecting a respective pair of the third radial conductors; a third conductive layer comprising: a fourth conductive layer on a second side of the second dielectric layer, the fourth conductive layer comprising a fourth conductive trace, the fourth conductive trace comprising: a fourth radial conductor extending radially from the first radial distance to the second radial distance; fourth conductive end turns, each of the fourth conductive end turns interconnecting a respective pair of the fourth radial conductors; a fourth conductive layer comprising: second blind or buried vias through the second dielectric layer, each of the third radial conductors being electrically connected to a corresponding one of the fourth radial conductors through at least one respective second blind or buried via; a third dielectric layer between the second conductive layer and the third conductive layer; and Equipped with none of the first blind or buried vias passes through the third dielectric layer; A PCS wherein none of the second blind or buried vias passes through the third dielectric layer.

2. the first radial conductor, the second radial conductor, the first conductive end turn, and the second conductive end turn establish an electrical path for a first portion of a winding that, when energized, generates magnetic flux for a first phase of the motor or generator; the third radial conductor, the fourth radial conductor, the third conductive end turn, and the fourth conductive end turn establish an electrical path for a second portion of the winding; 2. The PCS of claim 1, wherein the first portion of the winding is connected in series with the second portion of the winding.

3. 1. A planar composite structure (PCS) as a stator for use in an axial flux motor or generator, the PCS comprising: a first subassembly including a first conductive layer, the first conductive layer including a first radial conductor extending radially from a first radial distance to a second radial distance greater than the first radial distance, a first end-turn conductor, and a second end-turn conductor; the first end-turn conductors interconnect a first group of the first radial conductors and form a first winding for a first phase of the axial flux motor or generator, each of the first end-turn conductors interconnecting a respective pair of the first radial conductors associated with the same pole of the stator; the second end-turn conductors interconnect a second group of the first radial conductors and form a second winding for a second phase of the axial flux motor or generator, each of the second end-turn conductors interconnecting a respective pair of the first radial conductors associated with the same pole of the stator; The PCS, wherein the first subassembly includes more second end-turn conductors than first end-turn conductors.

4. a second subassembly, the second subassembly comprising a second conductive layer different from the first conductive layer, the second conductive layer including a second radial conductor extending radially from the first radial distance to the second radial distance, a third end-turn conductor, and a fourth end-turn conductor; the third end-turn conductors interconnect a first group of the second radial conductors and form a third winding for a first phase of the axial flux motor or generator, each of the third end-turn conductors interconnecting a respective pair of the second radial conductors associated with the same pole of the stator; the fourth end-turn conductors interconnect a second group of the second radial conductors and form a fourth winding for a second phase of the axial flux motor or generator, each of the fourth end-turn conductors interconnecting a respective pair of the second radial conductors associated with the same pole of the stator; The PCS of claim 3 , wherein the second subassembly includes more third end-turn conductors than fourth end-turn conductors.

5. the third winding is connected in series with the first winding; 5. The PCS of claim 4, wherein the fourth winding is connected in series with the second winding.

6. 6. The PCS of claim 4 or claim 5, wherein the number of the first end-turn conductors plus the number of the third end-turn conductors is equal to the number of the second end-turn conductors plus the number of the fourth end-turn conductors.

7. the first end turn conductor comprises a first inner end turn conductor and a first outer end turn conductor; the second end turn conductor comprises a second inner end turn conductor and a second outer end turn conductor; each of the first inner end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the first radial distance; each of the first outer end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the second radial distance; each of the second inner end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the first radial distance; each of the second outer end-turn conductors electrically interconnects portions of a respective pair of the first radial conductors at the second radial distance; the first subassembly includes the same number of first inner end-turn conductors as the number of second inner end-turn conductors; The PCS of any one of claims 3 to 6, wherein the first subassembly includes more second outer end-turn conductors than first outer end-turn conductors.

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