Patent Description:
Some axial field electric machines, such as motors or generators, use printed circuit board (PCB) stator structures. Examples of such apparatuses are described in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

<CIT> discloses another example of an axial field electric machine with a printed circuit board stator structure. These PCB stator structures are produced through a combination of etching, laminating, drilling and plating operations that can be repeated until a complete PCB stator is obtained. While the manufacturing process of these PCB stators is well established, it is desirable to simplify the manufacturing process to reduce costs. Some PCB stator designs require the PCB stator to be split into PCB panels that are processed individually, namely going through etching, laminating, drilling and plating operations, then undergoing additional laminating, drilling, and plating operations. By selecting and applying design features to the PCB stator, some of the previously mentioned repetitive operations can be eliminated resulting in a faster and more economical manufacturing process.

In a first aspect an axial field rotary energy device according to claim <NUM> is disclosed.

So that the manner in which the features and advantages of the embodiments of the aspects are attained and can be understood in more detail, a more particular description can be had by reference to the embodiments thereof that are illustrated in the appended drawings. However, the drawings illustrate only some embodiments and therefore are not to be considered limiting in scope as there can be other equally effective embodiments.

<FIG> disclose various embodiments of axial field rotary energy devices. Some axial field electric machines can include one, two or more PCB stators, such as one for each electrical phase of the machine. <FIG> depict a typical multiphase axial field rotary energy device, or multiphase device <NUM>. The multiphase device <NUM> can include at least one rotor <NUM> (two shown, in <FIG>) with an axis of rotation <NUM>. Each rotor <NUM> can comprise at least one magnet <NUM>. The multiphase device <NUM> can also include at least one PCB stator <NUM> that is coaxial with the rotor <NUM>.

Each PCB stator <NUM>, as shown in <FIG>, which is not according to the invention, can include a plurality of coils <NUM> etched, for example, in the copper foil of a laminated structure of the PCB. The coils <NUM> can be supported by a dielectric structure <NUM> made of, for example, epoxy-glass laminate, polyimide-glass laminate, or PTFE-ceramic laminate. The coils <NUM> can include multiple turns depending on the design of the PCB stator <NUM>. The coils <NUM> in the PCB stator <NUM> can be interconnected by means of traces (not shown in <FIG>) etched in the copper foil of a PCB laminate structure to form north and south poles. While <FIG> shows an example of a <NUM>-pole stator, many other pole configurations are possible.

<FIG> which is not according to the invention, depicts a coil <NUM> in more detail. Coil <NUM> can be formed as a continuous conductive trace <NUM> that can be etched out of a layer of copper foil laminated on a dielectric laminate such as FR4 glass-epoxy laminate, for example. The continuous conductive trace <NUM> of coil <NUM> can have perforations <NUM> at both of its terminal ends. The perforations <NUM> can connect coil <NUM> to other coils in the PCB stator <NUM>. Although coil <NUM> is shown as having <NUM>-turns, other PCB stators may have coils with different numbers of turns.

<FIG> which is not according to the invention, shows an embodiment where the coils are interconnected to form a continuous path, which is hereinafter referred to as a coil subassembly <NUM>. In <FIG>, the dielectric material of the PCB laminate structure is not shown for better visualization of the coil structure. In the coil subassembly <NUM>, a first coil <NUM> located on one layer of the PCB structure can have a first terminal <NUM> that can be connected to other coils, or to an external voltage source such as a variable frequency drive (VFD). A trace <NUM> can be etched on the copper of a PCB laminate structure to form turns that are terminated at a second terminal <NUM>. The second terminal <NUM> is coupled to a third terminal <NUM>, that is part of a second coil <NUM> located in another layer of the PCB structure, by means of a via, such as a plated via <NUM>. The second coil <NUM> can have a trace <NUM> that can be etched on the copper of the PCB laminate structure to form turns. The trace <NUM> can seamlessly connect and form turns of a third coil <NUM> that terminates at a fourth terminal <NUM>. The fourth terminal <NUM> can be coupled to a fifth terminal <NUM> that is part of a fourth coil <NUM> located in the same PCB layer as the first coil <NUM>. The fourth coil <NUM> can have a trace <NUM> that can be etched on the copper of the PCB laminate structure to form turns and terminate at a sixth terminal <NUM>. The sixth terminal <NUM> can be connected to still other coils, or to an external voltage source such as a VFD. Although coil subassembly <NUM> is shown as having coils with <NUM> turns, it should be understood that other coil subassemblies can have different numbers of turns.

<FIG> and <FIG> which are not according to the invention, show partial views of an embodiment of the PCB stator <NUM> where the dielectric material is not shown and the length of the vias is increased for better visualization. <FIG> shows an example of a <NUM>-phase PCB stator with two layers per phase. Each pair of layers can form a PCB panel that comprises a plurality of coil subassemblies <NUM>, <NUM> and <NUM>, respectively. Each PCB panel can be assigned to one electrical phase. Each coil subassembly <NUM>, <NUM>, <NUM> can comprise a set of plated vias <NUM>, <NUM> and <NUM>, respectively, that connect the coils in each coil subassembly <NUM>, <NUM>, <NUM> to form a continuous path.

<FIG> shows that the stator panels, and therefore the coil subassemblies, can be rotatably shifted relative to each other by <NUM> electrical degrees, which is <NUM> electrical degrees divided by the number of phases. Hereinafter, it should be noted that <NUM> electrical degrees cover the angular span of two consecutive poles, or a pair of poles. The PCB stator example shown in <FIG> has <NUM> poles. Thus, each pole in this one example has a physical span of <NUM> mechanical (or electrical) degrees and a pair of poles has a physical span of <NUM> mechanical (or electrical) degrees. In this example, <NUM> electrical degrees are equivalent to <NUM> mechanical degrees and <NUM> electrical degrees are equivalent to <NUM> mechanical degrees. The formula for this conversion is: mechanical degrees = electrical degrees / number of pairs of poles.

Although <FIG> and <FIG> show a <NUM>-phase stator structure, it should be understood that PCB stators can have <NUM>, <NUM>, <NUM>, <NUM>, or another number of phases. It should also be noted that although each phase in PCB stator <NUM> has one pair of layers per phase, other PCB stators can have <NUM>, <NUM>, <NUM> or more pairs of layers per phase.

In the example shown in <FIG> and <FIG>, it can be seen that if one of the vias <NUM> in coil subassembly <NUM> was extended along the line <NUM>, which is substantially co-linear with said one of the vias <NUM>, it would intersect the trace <NUM> in coil subassembly <NUM>. Similarly, if one of the vias <NUM> in coil subassembly <NUM> was extended along line <NUM>, which is substantially co-linear with said one of the vias <NUM>, it would intersect the trace <NUM> in coil subassembly <NUM>. Finally, if one of the vias <NUM> in coil subassembly <NUM> was extended along line <NUM>, which is substantially co-linear with said one of the vias <NUM>, it would intersect trace <NUM> in coil subassembly <NUM>.

<FIG> shows a top view of the PCB stator <NUM> where the locations of vias <NUM>, <NUM> and <NUM> are indicated. Similarly to <FIG>, it can be seen that vias <NUM>, which are in coil subassembly <NUM>, are substantially vertically aligned with traces <NUM> from other layers. Similarly, vias <NUM>, which are in coil subassembly <NUM>, are substantially vertically aligned with traces <NUM> from other layers. Finally, vias <NUM> of coil subassembly <NUM> are substantially vertically aligned with traces <NUM> from other layers. As this vertical alignment can cause vias to intersect traces in other PCB layers it requires that, during the PCB manufacturing process, each PCB panel can undergo the manufacturing process depicted in <FIG>.

<FIG> shows a flow diagram of an embodiment of a manufacturing process <NUM> for a PCB stator which is not according to the invention, were vias could intersect traces as depicted in the example in <FIG> and <FIG>. In the process shown in <FIG>, each PCB panel can undergo the process <NUM> that can include application of a photoresist, etching, resist stripping, panel lamination, via drilling and via plating. The process can be repeated for each phase of the PCB panel. After that, the phases panels of the PCB stators can undergo process <NUM>, where they are laminated together to form the complete PCB stator. Subsequently, they can be drilled, plated, coated with resist, etched, stripped of remaining resist and coated with a solder mask, for example. Although <FIG> describes a process for a stator with three PCB panels with one panel per electrical phase, it should be understood that other PCB stators can have <NUM>, <NUM>, <NUM>, <NUM> or more PCB panels with one panel per phase, so the process <NUM> can match the number of panels and/or phases.

In the example depicted in <FIG> and <FIG>, the reason that the vias <NUM>, <NUM>, <NUM> can intersect the other coil traces is because the number of coil turns is not a multiple of the number of phases. The example in <FIG> and <FIG> has coils with <NUM> turns which is not a multiple of <NUM>, which is the number of phases.

In contrast, <FIG> and <FIG> show an example of a <NUM>-phase PCB stator <NUM> that have coils with <NUM> turns, which is multiple of <NUM>, which is the number of phases in PCB stator <NUM>. In <FIG> and <FIG>, the dielectric material is not shown and the length of the vias are increased for easier visualization. In this example, the <NUM>-phase PCB stator <NUM> has <NUM> layers per phase. Each pair of layers can form a PCB panel that comprises a plurality of coil subassemblies <NUM>, <NUM> and <NUM>, respectively, and each PCB panel can be assigned to one electrical phase. Each coil subassembly can comprise a set of plated vias <NUM>, <NUM> and <NUM>, respectively, that connects the coils in each coil subassembly <NUM>, <NUM>, <NUM> to form a continuous path. Similarly to the example shown in <FIG> and <FIG>, the PCB stator panels in <FIG> and <FIG> are rotatably shifted relative to each other by <NUM> electrical degrees, which is <NUM> electrical degrees divided by the number of phases. It should be noted that although each phase in PCB stator <NUM> has one pair of layers, other PCB stators can have <NUM>, <NUM>, <NUM> or more pairs of layers per phase.

In the example shown in <FIG> and <FIG>, it can be seen that via <NUM> in coil subassembly <NUM> can be extended along the line <NUM>, which is substantially co-linear with via <NUM>, without intersecting any traces <NUM> in any other layers. Similarly, via <NUM> in coil subassembly <NUM> can be extended along the line <NUM>, which is substantially co-linear with via <NUM>, without intersecting any traces <NUM> in any other layers. Finally, via <NUM> in coil subassembly <NUM> can be extended along the line <NUM>, which is substantially co-linear with via <NUM> without intersecting any traces <NUM> in any other layers.

<FIG> shows a top view of PCB stator <NUM> where the vias <NUM>, <NUM> and <NUM> are indicated. It can be seen that the vias <NUM>, <NUM>, <NUM> do not intersect any traces <NUM> other than the traces in the layers that form the coils they are coupled to. In this embodiment where the number of turns of the coils is a multiple of the number of electrical phases, a via and its extension will intersect traces only in coils that belong to layers associated to that one phase. Said via and its extension will not intersect traces in coils that belong to layers associated with the other phases.

The via arrangement depicted in <FIG> and <FIG> allows for a PCB manufacturing process <NUM> depicted in <FIG>, which has fewer steps than the manufacturing process <NUM> depicted in <FIG>. This is because all PCB stator layers can be laminated, via drilled and plated in one single step, which is faster and more economical than the manufacturing process <NUM> depicted in <FIG>.

Due to requirements of axial field electric machine applications such as power, current and voltage, the PCB stator can have coils connected in series, parallel, or a combination of both. According to the invention, each coil of the PCB stator has two or more parallel traces. Thus, the current flowing through the coils of the PCB stator can be split among parallel traces.

The traces do not intersect each other along the coils, because that would create paths for eddy current circulation, which would create eddy current losses and degrade machine efficiency.

<FIG> shows an example of a PCB stator <NUM> according to the invention with parallel traces that can include a plurality of coils <NUM>, <NUM> through <NUM>. m, and coils <NUM> through <NUM>. The coils may be etched, for example, in the copper foil of a laminated structure of the PCB. These copper coils can be supported by a dielectric structure <NUM> formed from, for example, epoxy-glass laminate, polyimide-glass laminate, or PTFE-ceramic laminate. The coils <NUM>, <NUM> through <NUM>. m, and <NUM> through <NUM>. n can include multiple turns depending on the design of the PCB stator. While <FIG> shows an example of a <NUM>-pole stator, many other pole configurations are possible. The PCB stator example shown in <FIG> has three turns per coil, however, other PCB stators can have coils with other numbers of turns.

<FIG> shows an embodiment of an individual coil <NUM> which can have a terminal <NUM> that can be connected to an external voltage source, such as a VFD, at a first end <NUM>. At a second end <NUM>, the terminal <NUM> can be split into multiple parallel traces <NUM> that form the coil <NUM>. Although <FIG> shows the coil <NUM> with three parallel traces <NUM>, other embodiments can have coils with two, four, five or more parallel traces.

Each trace <NUM> in coil <NUM> (which, in <FIG>, is the coil 610a, on the left) terminates in a respective terminal <NUM> (<FIG>). The terminals <NUM> are not connected to each other in any of the coils 610a, <NUM> through <NUM>. m, or <NUM> to <NUM>. n, until they circumscribe (in a counterclockwise direction, in <FIG>) the entire PCB stator <NUM>. The only point where the traces <NUM> reconnect is the second end <NUM> of terminal <NUM> of the second coil 610b (on the right side of <FIG>). Thus, the current from the external source can enter at coil 610a (via terminal <NUM>), split into traces <NUM> and then exit at the terminal <NUM> of coil 610b.

<FIG> shows a detailed view of an embodiment of a PCB stator where the dielectric structure is not shown for ease of understanding. In some versions, the coil <NUM> can be in one layer and connected to a coil <NUM> in another layer with vias <NUM>. Coil <NUM> can have a first part <NUM>. <NUM> that can be circumferentially aligned with coil <NUM>. A second part <NUM>. <NUM> can be in the same layer and adjacent to the first part <NUM>. <NUM> to form a continuous path of three non-intersecting traces. The second part <NUM>. <NUM> can be connected (with vias <NUM>) to a first part <NUM>. <NUM> of a coil <NUM> that is in the same layer as coil <NUM>. Second part <NUM>. <NUM> and first part <NUM>. <NUM> can be circumferentially aligned.

The second part <NUM>. <NUM> of coil <NUM> can be connected with vias <NUM> to a first part <NUM>. <NUM> of a coil <NUM> that is located in the same layer as the coil <NUM>. Coils <NUM> and <NUM> can be identical to each other. Second part <NUM>. <NUM> and <NUM>. <NUM> can be circumferentially aligned. The second part <NUM>. <NUM> of the coil <NUM> can be connected to the first part <NUM>. <NUM> of a coil <NUM> that is located in the same layer as the coil <NUM> and coil <NUM>. Coils <NUM>. And <NUM> can be identical to each other. Coils <NUM>. <NUM> and <NUM>. <NUM> can be circumferentially aligned. This pattern can repeat for the entire circumference of the PCB stator for up to coils <NUM>. m and <NUM>. In an example, the second part <NUM>. <NUM> of the last coil <NUM>. m can connect to another coil <NUM> (which can be identical to the original coil <NUM>), as shown in <FIG>.

According to the invention, the traces <NUM> (<FIG>) only intersect each other at the terminals <NUM> at both ends of the PCB stator panel winding. A continuous serial path is formed through the vias connections that each trace in each coil forms with corresponding traces in other coils.

Embodiments of the PCB stator <NUM> can have coils where the number of turns is a multiple of the number of phases. <FIG> depicts a partial view of the PCB stator <NUM> having three panels <NUM>, <NUM> and <NUM>, and each panel is assigned to one phase. In this embodiment, panels <NUM>, <NUM> and <NUM> have one pair of layers each, however other embodiments can have more than one pair of layers.

<FIG> shows a detailed view of a portion of the PCB stator <NUM> where the dielectric structure is not shown for ease of understanding. PCB Stator <NUM> is <NUM>-phase stator and has coils with <NUM> turns. There is a <NUM> electrical degree phase shift between the vias <NUM>, <NUM> and <NUM>, which can represent the phase shift between panels <NUM>, <NUM> and <NUM>, respectively. The via extensions <NUM>, <NUM> and <NUM> can extend from the vias <NUM>, <NUM> and <NUM>, respectively, and intersect only the traces associated with the respective phases.

<FIG> is an enlarged cross-sectional view of a portion of a PCB stator showing a via and PCB layer details.

<FIG> is a process flow chart for manufacturing an embodiment of a PCB stator.

<FIG> is an enlarged view of a surface detail of a PCB stator.

<FIG> is a further enlarged view of the detail shown in <FIG>.

<FIG> shows a partial cross section of a PCB stator <NUM>. PCB stator <NUM> includes a via <NUM> that can extend from one major surface (e.g., flat surface, in some examples) of the PCB stator <NUM> to another major surface thereof. The via <NUM> can be plated (see, e.g., step <NUM> in the manufacturing process <NUM> shown in <FIG>) with a material having high thermal conductivity, such as copper, for example. The vias <NUM> can include one or more substantially cylindrical, electrically conductive tubes <NUM> that extend from one major surface of the PCB stator to the opposing major surface. The conductive tubes <NUM> are alternatively depicted as vias <NUM> and <NUM> in <FIG>, for example. As shown in <FIG>, the tube <NUM> can be electrically connected to selected ones of the traces <NUM> while selectively not intersecting other traces <NUM> in the PCB stator <NUM>.

During the plating process <NUM> (<FIG>), and in addition to the conductive tube <NUM>, a conductive pad <NUM> can be formed on the outer surface of the PCB stator <NUM>. In normal operation of the axial field rotary energy device, a voltage of hundreds of volts can be applied to the pad <NUM>, in some examples. In order to prevent an electrical hazard, such as an electric discharge between a pad <NUM> and the surface of a rotor <NUM> of the axial field rotary energy device <NUM> shown in <FIG>, layers of B-stage glass-epoxy laminate, for example, can be laminated onto the external major surfaces of the PCB stator <NUM>. The laminate can form a dielectric layer <NUM> that can completely cover and isolate the pad <NUM> electrically from surrounding components, such as rotor <NUM>.

The lamination of the dielectric layer <NUM> is represented by step <NUM> (<FIG>) in the PCB stator manufacturing process <NUM>. This process can be simpler and more economical than the manufacturing processes <NUM> and <NUM> (<FIG> and <FIG>, respectively) where a solder mask coat is applied to the surfaces of the PCB stator. The dielectric layer <NUM> can have a high dielectric strength, such as <NUM> kV/mm, for example, and can enable the PCB stator <NUM> to withstand up to <NUM>,<NUM> Vdc or more during high voltage testing in some embodiments. This represents a substantial improvement over a typical solder mask coat which is not intended to provide dielectric protection and cannot withstand more than <NUM>,<NUM> Vdc in a high voltage test, for example. Embodiments of the PCB stator manufacturing process <NUM> can include other steps such as a resist coat lamination <NUM>, an etch and strip resist <NUM>, stator lamination <NUM> and stator drilling <NUM>.

Some embodiments can have a laminated dielectric layer <NUM> made of a B-stage glass epoxy laminate, with typical off-plane thermal conductivity of <NUM> to <NUM> W/m. Other embodiments can employ a B-stage glass epoxy laminate with high off-plane thermal conductivity in the <NUM> to <NUM> W/m. Furthermore, some embodiments can employ glass reinforced laminates with other resins, such as polyimide or polytetrafluorethylene based resins or others.

The dielectric layer <NUM> can be configured to conform to features on the surface of the PCB stator <NUM>. <FIG> shows an example of an embodiment of the dielectric layer <NUM> with a cutout <NUM> forming a recess providing clearance around conductive pads <NUM>. The conductive pads <NUM> can receive, by means of soldering, an resistance temperature detector (RTD), for example, to sense the temperature of the PCB stator <NUM> during operation. The conductive pads <NUM> can be configured to receive other sensors <NUM> (shown schematically in <FIG>) such as thermistors, accelerometers, or other sensing devices. The conductive pads <NUM> can be connected to terminals <NUM> (<FIG>) by means of conductive traces <NUM>. The conductive pads <NUM>, terminals <NUM> and conductive traces <NUM> can be made from copper or other metal or alloy with good electrical conductivity and can be formed by etching.

In order to contain the solder alloy and prevent it from causing a short circuit or a runoff on the surface of the PCB stator <NUM> while soldering a device to pads <NUM>, a masking pattern <NUM> can be applied to the surface of the PCB stator <NUM>. The masking pattern <NUM> can be applied with a silk-screen printing or ink jet printing, for example. Such processing can eliminate the need to apply a solder mask, which is a more complicated and expensive process. As shown in <FIG>, the masking pattern <NUM> can be configured to cover the conductive traces <NUM> that connect the conductive pads <NUM> to terminals <NUM> to protect conductive traces <NUM> from oxidation. The masking pattern <NUM> can comprise an extension <NUM> that provides a barrier to prevent molten solder from bridging the gap between the adjacent conductive pads <NUM> during the soldering operation. The masking pattern <NUM> can further comprise a contour <NUM> for preventing molten solder from running off over the surface of the PCB stator <NUM>. The masking pattern <NUM> can be <NUM> thick, for example, however other thicknesses can also be employed.

Other embodiments can include one or more of the following items.

In particular according to a twenty-ninth embodiment, an axial field rotary energy device comprising:.

In particular in a thirtieth embodiment that may refer to the twenty-ninth embodiment, the device comprising one or more of:
each end of the plated vias comprises plated pads; the dielectric layer has an off-plane thermal conductivity that is greater than <NUM> W/m. K; or the dielectric layer has a dielectric strength of <NUM> kV/mm or more.

In particular in a thirty-first embodiment that may refer to the twenty-ninth embodiment, the device further comprising one or more of:.

In particular in a thirty-second embodiment that may refer to the thirty-first embodiment, the device further comprising one or more of:
the masking pattern is at least <NUM> thick; the plated vias have plated pads at each end; the dielectric layer has an off-plane thermal conductivity that is greater than <NUM> W/m. K; or the dielectric layer has a dielectric strength of <NUM> kV/mm or more.

In particular in a thirty-third embodiment that may refer to the twenty-ninth embodiment, the device further comprising:.

In particular in a thirty-fourth embodiment that may refer to the twenty-ninth embodiment, the plated vias have plated pads at each end.

In particular in a thirty-fifth embodiment that may refer to the twenty-ninth embodiment, the layer of dielectric material has an off-plane thermal conductivity that is greater than <NUM> W/m.

In particular in a thirty-sixth embodiment that may refer to the twenty-ninth embodiment, the layer of dielectric material has a dielectric strength of <NUM> kV/mm or more.

In particular in a thirty-seventh embodiment that may refer to the twenty-ninth embodiment, the device further comprising conductive pads coupled to sensors, and the conductive pads are connected to terminals through conductive traces.

In particular in a thirty-eighth embodiment that may refer to the thirty-seventh embodiment, the conductive pads, terminals and conductive traces, are comprised of an electrically conductive material.

In particular in a thirty-ninth embodiment that may refer to the thirty-seventh embodiment, the dielectric layer on at least one of the major surfaces of the PCB stator has cut outs that provide clearance around the conductive pads.

In particular in a fortieth embodiment that may refer to the thirty-seventh embodiment, the device further comprising a masking pattern that covers conductive traces and forms barriers to prevent molten solder from bridging across adjacent ones of conductive pads and from running off on the major surfaces of the PCB stator.

In particular in a forty-first embodiment that may refer to the twenty-ninth embodiment, each major surface of the PCB stator is laminated with the dielectric material layer.

In particular according to a forty-second embodiment, an axial field rotary energy device comprising:.

In particular in a forty-third embodiment that may refer to the forty-second embodiment, the layer of dielectric material has an off-plane thermal conductivity that is greater than <NUM> W/m.

In particular in a forty-fourth embodiment that may refer to the forty-second embodiment, the device further comprising:.

In particular in a forty-fifth embodiment that may refer to the forty-fourth embodiment, the masking pattern is at least <NUM> thick.

In particular in a forty-sixth embodiment that may refer to the forty-fifth embodiment, the layer of dielectric material has an off-plane thermal conductivity that is greater than <NUM> W/m.

Spatially relative terms, such as "inner," "outer," "beneath," "below," "lower," "above," "upper," "top", "bottom," and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The device may be otherwise oriented (rotated degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

This written description uses examples to disclose the embodiments, including the best mode, and also to enable those of ordinary skill in the art to make and use the invention. The patentable scope is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

In the foregoing specification, the concepts have been described with reference to specific embodiments. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of invention.

It can be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term "communicate," as well as derivatives thereof, encompasses both direct and indirect communication. The phrase "associated with," as well as derivatives thereof, can mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items can be used, and only one item in the list can be needed.

This description should be read to include one or at least one and the singular also includes the plural unless it states otherwise.

The description in the present application should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims.

However, the benefits, advantages, solutions to problems, and any feature(s) that can cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, sacrosanct or an essential feature of any or all the claims.

Claim 1:
An axial field rotary energy device (<NUM>), comprising:
a rotor (<NUM>) comprising an axis of rotation and a magnet;
a stator (<NUM>,<NUM>) coaxial with the rotor, the stator comprising printed circuit board (PCB) panels, each PCB panel is assigned to one electrical phase of the device, each PCB panel comprises at least one pair of PCB layers, and each PCB layer comprises coils;
characterized in that each coil in each PCB layer of a given PCB panel is circumferentially aligned with a corresponding coil in another PCB layer of the given PCB panel; wherein
one coil in one PCB layer is coupled to a corresponding coil in another PCB layer of the given PCB panel with a respective via (<NUM>,<NUM>); and
a number of turns in each coil is a multiple of a number of electrical phases configured for the device so that said vias (<NUM>) and its extensions will not intersect traces (<NUM>) of coils that belong to PCB layers associated with other phases,
or
each coil in each PCB layer of said given PCB panel is circumferentially aligned and coupled with a corresponding coil in another PCB layer of the given PCB panel; and each coil comprises traces (<NUM>) that are not connected to each other except at terminals (<NUM>) of a first coil and a last coil of the coupled coils of a respective one of the pair of PCB layers.