STATOR FOR AN ELECTRICAL MACHINE

Abstract

A stator for interacting with magnets carried by a rotor of an electric machine, the stator comprising: an active region arranged to align with the magnets carried by the rotor; a first inactive region and a second inactive region, wherein the first and second inactive regions are separated by the active region; and a slotless phase winding comprising a plurality of conducting elements, wherein each conducting element comprises a conductor provided in an insulating housing, and wherein the slotless phase winding is arranged in a serpentine structure comprising: a first active segment where the conducting elements extend through the active region from the first inactive region to the second inactive region; a second active segment where the conducting elements extend throughout the active region from the second inactive region to the first inactive region;and an inactive segment coupling the first active segment to the second active segment, where the inactive segment comprises a proportionate twist in the second inactive region, and where at least one of the conducting elements is twisted in the second inactive region.;

Description

Technical field This disclosure relates to the field of stators for electrical machines. Background of the invention Electrical machines, such as motors, are designed to convert electrical energy into mechanical energy. Electrical machines typically include a stator and a rotor. The stator surrounds the rotor and contains one or more windings. The rotor has one or more magnets and is attached to a shaft. When current is applied through the stator windings, the resulting magnetic field interacts with the rotor magnets to drive the rotation of the rotor and shaft. Today, small but powerful electric motors are used in many different mobile applications, such as lawnmowers or battery-powered or hybrid vehicles. In the past, such machines were primarily powered by combustion engines. Brief description of the invention The disclosure aspects are set forth in the independent claims, and the optional features are set forth in the dependent claims. The disclosure aspects may be provided in conjunction with each other, and the features of one aspect may apply to other aspects. In one aspect, a stator is provided for interacting with magnets carried by a rotor of an electric machine. The stator comprises: an active region arranged to align with the magnets carried by the rotor; a first inactive region and a second inactive region, wherein the first and second inactive regions are separated by the active region; and a slotless phase winding comprising a plurality of conductive elements. Each conductive element comprises a conductor provided in an insulating housing.The slotless phase winding is arranged in a serpentine structure comprising: a first active segment where the conductive elements extend through the active region from the first inactive region to the second inactive region; a second active segment where the conductive elements extend throughout the active region from the second inactive region to the first inactive region; and an inactive segment coupling the first active segment to the second active segment, where the inactive segment comprises a provided twist in the second inactive region, and where at least one of the conductive elements is twisted in the second inactive region. These modifications can provide a more efficient stator. In particular, the stator can reduce circulating voltage losses and / or eddy currents incurred during stator operation. The stator can provide an efficient, spacious stator. The insulating casing for each of the conductive elements can reduce eddy current losses associated with its respective conductor during stator operation. Twisting at least one of the conductive elements can vary the separation distance between each conductor and the magnets carried by the rotor (for example, so that this separation distance changes over the active region of the stator).This can reduce the total voltage integral associated with the stator because, while the individual subintegrals for smaller portions of the winding may deviate (e.g., increase or decrease relative to adjacent portions of the winding), these deviations will average out over the entire stator. In turn, this will reduce the overall total voltage integral for the stator, thus providing greater efficiency for stator operation. For example, the arrangement of conductive elements and one or more idle-line twists can be selected to minimize the voltage integral for the stator as a whole (e.g., across one or all of the stator phase windings). The electrical machine may comprise a slotless DC machine. The electrical machine may be arranged to operate as a motor and / or a generator. In this way, the stator and rotor windings may be arranged to interact so as to transmit: (i) electrical energy (in the form of current / voltage applied to the stator windings) from the stator to kinetic energy (in the form of rotation) of the rotor, and / or (ii) kinetic energy (in the form of rotation) of the rotor to electrical energy (in the form of resulting current) in the stator. In a motor, the stator is configured to selectively apply current to the phase winding to generate a corresponding magnetic field to interact with the rotor magnets. This magnetic field will provide a resultant force to the permanent magnets in the rotor. The force on the rotor magnets will cause the magnets (and therefore the rotor itself) to move relative to the stator windings. In particular, the rotor can be configured to rotate around an axis of rotation, and the selective application of current to the phase winding can cause the rotor to rotate around its axis of rotation. In other words, in a motor, the stator is configured to selectively apply current to the phase winding to drive rotor rotation.For example, the stator is for interacting with magnets carried by a rotor of an electric motor, and the stator is configured to apply current to the slotless phase winding to drive the rotation of the electric motor's rotor. For a generator, energy is transmitted to the rotor from an external source, causing the rotor to spin around its axis. As it does so, the rotation of the permanent magnets relative to the stator's phase winding induces a current in the phase winding. This resulting current can be harnessed as electrical energy (for example, for storage or to power electrical circuits). In other words, the stator is configured to selectively harness the electrical energy produced by the rotation of the rotor's permanent magnets relative to the stator's phase winding. For example, the stator is designed to interact with magnets carried by a generator's rotor, and the stator is configured to harness the energy of a resulting current generated in the non-slotted phase winding in response to the rotation of the generator's rotor magnets. The stator is arranged to operate in combination with the rotor. In particular, the stator can be configured so that, when used in combination with a rotor, the stator phase winding MA / t / zuzz / uouy / y will align with the rotor's permanent magnets. The permanent magnets can occupy an active area of ​​the rotor. That is, the rotor magnets can be provided on a rotor surface that forms the active area. The magnetic field of the permanent magnets will be strongest in a volume adjacent to this active area. In particular, the magnetic field will be strongest in the region aligned with the rotor's active area, and this magnetic field will decrease in strength with increasing distance from the permanent magnets. The stator can be controlled to operate based on signals received from a sensor on the electric machine. For example, a sensor can be provided to detect the rotor's rotational position, and the stator's operation can be controlled based on this detected rotational position. The stator can be arranged to align with the rotor so that the rotor's active area (where the permanent magnets are located) is aligned with the active region of the stator's phase winding. This may include the stator's active region being offset horizontally or vertically from the rotor's active area. However, the stator's active region may only be offset vertically, or only horizontally, for example, to maximize the alignment between the stator's active region and the rotor's active area. The stator's inactive regions may include areas that are not aligned with the rotor magnets. The inactive regions may also include areas located beyond the ends of the rotor's active region. In other words, the active region of the stator can be defined as the region where the magnetic field generated by the rotor's permanent magnets is strongest. For example, the active region might be the region aligned with the rotor when the rotor is in position relative to the stator in the electrical machine. The inactive regions of the stator can be defined as the region where the magnetic field from the permanent magnets is weakest (for example, regions not aligned with the magnets). The stator can be configured for one of two different types of clearance between the stator and the rotor of the electrical machine used in combination with the stator. That is, the stator / rotor can have either radial or axial clearance. As a first example, the stator can be arranged to provide a radial air gap between the stator and the rotor. In this case, the stator and rotor can be coaxial with each other about the rotor's axis of rotation, and the two can be offset radially relative to each other about the same axis. For example, the stator can be arranged radially outward from the rotor. The stator can enclose a volume within which the rotor can be provided. Therefore, the stator can form a hollow cylinder, as can the air gap between the stator and the rotor. The rotor can be cylindrical and provided within the hollow stator cylinder. Permanent magnets can be provided on a surface of the rotor cylinder. The active area of ​​the rotor can be a cylindrical surface on which the magnets are provided.The active region of the stator can be configured to correspond to the active area of ​​the rotor, such that the active region of the stator also comprises a cylindrical surface. This cylindrical surface (active region) of the stator can be arranged to align with the cylindrical surface (active area) of the rotor in such a way that the active area of ​​the rotor fits within the active region of the stator. Both longitudinal ends of the... The rotor's active area can fit within the longitudinal extent of the stator's active region (for example, the longitudinal ends of the rotor's active area and the stator's active region can be the same). The stator's inactive regions can comprise areas that are axially offset from the stator's active region and / or the rotor's permanent magnets (active area). For example, the first inactive region can be axially offset from the second inactive region. The stator's active region can be located axially between the first and second inactive regions (as can the rotor's permanent magnets). For a radial air-gap stator, the conducting elements of the phase winding can be positioned parallel to the rotor's axis of rotation in the stator's active region. That is, in the active region, the active segments extend axially. The conducting elements rotate in each inactive region so that they can then extend axially through the stator's active region into the next inactive region. The rotation in each inactive region can be through 180° to reverse the axial direction of the conducting elements. The conducting elements may twist as they extend around the rotation. As a second example, the stator can be arranged to provide an axial air gap between the stator and the rotor. In this case, an axial offset between the stator and the rotor can be provided. The stator and rotor can be coaxial with each other. Both the stator and the rotor can be circular in cross-section (in the cross-section perpendicular to their axial direction). Permanent magnets can be arranged in a ring on a surface of the rotor. The rotor surface can have a central circular region where no permanent magnets are provided. Radially outward from the central circular region can be the annular region containing the permanent magnets. Radially outward from the annular region containing the permanent magnets can be another region without permanent magnets.The annular region of the rotor surface can provide the rotor's active area (e.g., the region where the permanent magnets are located). The rotor's annular active area can be aligned with the stator's active region. In other words, the stator's active region can comprise an annular region that is aligned with the rotor's active area, such that the two are axially offset, but the rotor's active area does not extend radially into or out of the stator's active region. The stator's inactive regions can be those radially into and out of the stator's active region (e.g., regions that are not axially aligned with the rotor's permanent magnets). For an axial air-gap stator, the conducting elements of the phase winding can extend radially across the active region of the stator. In other words, the active segments of the slotless phase winding can extend in a radial direction orthogonal to the rotor's axis of rotation. That is, in the active region of the stator, the conducting elements will extend radially toward / away from a center point on the stator surface. In the inactive regions, the elements can rotate so that they extend back across the active region in a radial direction toward the other inactive region. The stator may include a flux ring. The phase winding may be coupled to the flux ring. For example, the phase winding may be mounted directly on the flux ring, and / or the phase winding may be mounted on an intermediate layer (such as a polymer layer) to secure the winding to the flux ring. For a radial air-gap stator, the flux ring may include a hollow cylinder arranged to enclose the phase winding (and permanent magnets in the rotor). For an axial air-gap stator, the flux ring may include a disk arranged to be axially offset from the active region of the stator (and permanent magnets in the rotor) and to encompass the radial extent of the winding. The flux ring may be located on the opposite side of the phase winding from the permanent magnets in the rotor.The conductive elements may be separated from the permanent magnets by the air gap (for example, and nothing else). The stator may also include a housing where the stator components are provided. Each conductive element comprises a conductor provided within an insulating shell. The insulating shell may completely enclose the conductor along its length. The insulating shell may isolate each conductor from adjacent conductors in the phase winding. The phase winding comprises a plurality of conductive elements. The conductive elements of the phase winding may be bundled. A bundle may comprise a plurality of stacked conductive elements. The conductive elements may be stacked in bundles according to a selected shape (e.g., so that the bundle provides a selected cross-sectional shape). The selected shape may be symmetrical about at least one axis. The selected shape may be symmetrical about a plurality of axes.For example, the selected shape might allow the bundle to rotate while maintaining its cross-sectional shape, but the arrangement of the conductive elements within that shape has changed. For instance, the bundle's cross-sectional shape might have orthogonal sides (e.g., squares or rectangles), or the sides might not be orthogonal but still allow rotation of the shape into a different configuration of conductive elements while preserving that shape (e.g., according to any regular polygon). For example, the conductive elements might be arranged in a hexagonal structure. The cross-sectional shape of each conductor element may be uniform. The insulating sheath may have the same thickness around the conductor. The cross-sectional shape of each conductor may be selected to correspond to the cross-sectional shape of the bundle (or not). For example, the conductors may be hexagonal, circular, or rectangular in cross-section. The conductors may be symmetrical about at least one axis. The conductor may have a cross-sectional shape such that it can be rotated around at least one angle (not a multiple of 360°) so that its shape is preserved, but its relative orientation changes. Each conductor element may have a thickness (e.g., diameter) between 10 micrometers and 2000 micrometers, such as between 100 micrometers and 700 micrometers, or, for example, between 160 micrometers and 400 micrometers. The conductor of each conductive element may be parallel to the conductors of other conductive elements in the same bundle. For example, in the stator's active region, the bundle conductors may extend across the active region parallel to each other. The conductors may be untwisted and not compressed in the active region. The conductors may be untwisted in the active region. The conductors may be arranged to increase the conductive density within the bundle in the active region; for example, the conductors may be stacked parallel to each other (geometrically parallel, rather than electrically parallel). The phase winding may include terminal wires. The phase winding may be coupled to a commutator, such as a multi-phase commutator (for example, when operating as a motor). The phase winding may be coupled to a power supply to provide current to the windings.A voltage subintegral can be created on each conducting element separately (for example, because the element is electrically isolated). The serpentine structure may comprise a plurality of active segments and a plurality of inactive segments. The serpentine structure may be arranged in series such that each active segment leads to an inactive segment, and the inactive segment then leads to a subsequent active segment. For example, in each active segment, the conducting elements may extend directly through the active region from one inactive region to the next. Each inactive segment may couple two active segments together via a turn, so that the conducting elements may again extend directly through the active region of the stator from one inactive region to the other. Each active segment in the phase winding may be separated from its adjacent active segments by a threshold distance (e.g., to allow active segments of other windings to be supplied in the separation region).Each of the conductive elements in the phase winding (for example, in the same package) can follow the same serpentine path around the stator. Each active segment may comprise a region where the conductive elements are aligned with the rotor's permanent magnets (e.g., in a region where the magnetic field strength is relatively high). Each inactive segment may comprise a region where the conductive elements are not aligned with the rotor's permanent magnets, such as being axially or radially offset from the magnets (e.g., in a region where the magnetic field strength is relatively low). The conductive elements in the active segment are arranged for interaction with the rotor magnets. For example, for a radial spacing, the conductive elements in each active segment extend axially (parallel to the rotor's axis of rotation) between the inactive regions. Therefore, the active segments are a series of straight axial segments arranged on the surface of the cylinder that is aligned with the rotor magnets.For example, in an axial space, the conductive elements in each active segment extend radially (orthogonal to the rotor's axis of rotation) between the inactive regions. Therefore, the active segments are a series of straight radial segments arranged in an annular region that is aligned with the rotor magnets. Each conducting element can move from the active region to an inactive region, and that conducting element rotates so that it can re-enter the active region from that inactive region. Current flow along the conductor of each conducting element will travel from the active region to the inactive region, where that element rotates so that current flows back to the inactive region. Each turn can provide a path of continuity by which the conducting element rotates to return to the active region. The turn may or may not include a twist. When no twist is provided, the turn can bend the conducting elements around so that they return to the active region from the inactive region in the same configuration in which they entered the inactive region.When a twist occurs in an inactive region, the conducting elements will bend back to the active region from the inactive region, but they will be arranged in a different configuration than when they entered the inactive region. The twist may involve a bend in the same plane, or the bend may include a component outside that plane. For example, the first active segment and the inactive segment may lie in the same plane, or the inactive segment may extend out of that plane as it twists in the inactive region. The twist may involve a bend of the conducting elements so that they change the direction in which they extend from a first direction (through the active region from the first inactive region to the second inactive region) to a second direction (back through the active region from the second inactive region to the first inactive region). The plurality of conducting elements may be substantially parallel to each other in the first and / or second active segment. For example, in each active segment of the phase winding, the conducting elements within that bundle will be parallel to each other across the active region. The conducting elements may not be parallel to each other in the inactive regions (e.g., when twisted and / or rotated). The conducting elements in the first active segment may be substantially parallel to the conducting elements in the second active segment. For example, for a radially spaced stator, each of the active segments may be parallel to each other and to the rotor's axis of rotation.For an axial-space stator, each active segment may not be parallel to its adjacent active segment, but the separation distance between adjacent active segments at a boundary between the active region and the first inactive region may correspond to the separation distance between those adjacent active segments at a boundary between the active region and the second inactive region. For example, two adjacent active segments in an axial-space stator may extend along lines such that the two lines would intersect at the center of the stator (if extended that far). The conducting elements may extend straight and without twisting through the active region. At least one of the conductive elements is twisted in the inactive region. For example, twisting can occur when at least one conductive element is extended around the turn. Twisting can be relative to a single conductive element within a phase winding, or relative to the plurality of conductive elements of the phase winding as a whole (e.g., the bundle of conductive elements that forms the phase winding). For example, twisting can comprise a rotation about a longitudinal axis, such as a rotation of an individual conductive element about its own longitudinal axis, and / or a rotation of a bundle of conductive elements about its own longitudinal axis. The longitudinal axis of an individual conductive element can comprise the central axis that extends along the length of that element as it traces its path along the serpentine structure.The longitudinal axis of the conductive element bundle may comprise the central axis of the bundle that extends along the length of the bundle along the serpentine structure. MA / t / zuzz / uouy / y A conductive element can be twisted in the sense that it has been rotated relative to its longitudinal axis. The conductive element can move from the first active segment to the inactive segment, which has a particular orientation, and then from the inactive segment to the second active segment, which has a different orientation. For example, the orientation of the conductive element can change, so that the conductive element is provided in a different orientation in adjacent active segments. For example, the conductive element in the first active segment may be in a different rotational position relative to the conductive element in the second active segment. A conductive element may be twisted in such a way that its position and / or orientation relative to the other conductive elements of the phase winding has changed. For example, the arrangement of the conductive elements within the plurality of conductive elements of the phase winding may have changed between the first and second active segments. For example, for any conductive element of the phase winding, its separation distance from the rotor magnets may change as it extends along the serpentine structure (e.g., so that in some active regions that conductive element is closer to the rotor magnets than in other active segments). For the phase winding, the plurality of conductive elements can be bundled into a single bundle. The bundle can have a selected cross-sectional shape. The selected cross-sectional shape for the bundle can be the same in adjacent active segments (for example, the selected cross-sectional shape can remain constant for all active stator segments). However, the arrangement of the conductive elements within that bundle can change between different active segments, for example, so that the conductive elements in later active segments have a different positional configuration. For example, when observing the cross-sectional bundle in the first active segment compared to the second active segment, one or more of the conductive elements may have rotated individually and / or the bundle itself may have rotated completely.As a result, the configuration of the plurality of conductive elements in the phase winding will change between the first and second active segments. Therefore, at least one of the conductive elements will be separated from the rotor magnets by a different distance, or will be in a different orientation relative to the magnets, in the second active segment compared to the first active segment. For example, a plurality of conductive elements can be packed into a bundle. The bundle can be twisted in the second inactive region. For example, the bundle can twist as it extends around the twist in the second inactive region. The arrangement of the different conductive elements within the bundle can change as the bundle twists. As a result, at least one of the conductive elements within the bundle will be at a different separation distance from the rotor magnets in the second active segment compared to the first active segment. For example, the twisting bundle can involve a rotation of the bundle relative to its longitudinal axis. The shape of the bundle can be the same in cross-section in the first and second active segments, but the arrangement of the conductive elements within that bundle may have changed between the first and second active segments.The coil can be twisted in each inactive region of the stator, or only in some of the inactive regions. For example, subsequent twists can be the same; for instance, a twist in the first inactive region might involve a selected amount of rotation of the coil about its longitudinal axis, and the subsequent twist in the second inactive region might involve the same amount of rotation. The subsequent twist might involve the rotation to reverse the previous twist, so that every second active segment (where the twist has occurred) will have the conducting elements arranged in the same configuration. The turn in the inactive region may involve a change in the direction of the phase winding (e.g., a change in the direction of current flow). Each turn may reverse the direction of the phase winding, so that the conductive elements can extend again through the active region from one inactive region to the other. The turn in the inactive region may involve a change in the arrangement and / or orientation of the individual conductive elements within the bundle / the bundle as a whole. Torsion may occur during the turn. The inactive segment of the serpentine structure of the slotless phase winding may be a first inactive segment, and the serpentine structure of the slotless phase winding may further comprise a second inactive segment and a third active segment. The second inactive segment may couple the second active segment to the third active segment. The second inactive segment may include a provided twist in the first inactive region. At least one of the conductive elements may be twisted in the first inactive region; for example, the twisting may occur during the turning. The twisting in the first inactive region may comprise a half-twist (for example, a 180° rotation of a bundle of conductive elements around the longitudinal axis of the bundle). The twisting in the second inactive region may also comprise a half-twist.A twist can result in a change in the position of individual conductive elements within the bundle and / or a change in the orientation of the conductive elements / bundle. For example, the twist can be configured so that the internal arrangement of the conductive elements in the first active region differs from that in the second active region. A half-twist can involve a 180° rotation when comparing the first active segment to the second active segment. The conductive elements and / or the entire bundle can be twisted and / or compressed in the inactive regions. The conductive element bundle can be at least 5 elements deep, or as deep as 10 elements. In other words, the conductive elements forming the bundle can be arranged in layers, with at least 5 (for example, 10 or more) layers of separate conductive elements included. The element bundle can be mechanically connected and / or supported. For example, an encapsulation material can be used to join the different conductive elements. For example, the conductive elements can be molded together; for example, the stator itself (including the conductive elements) can be molded from a polymer or resin to provide structural support. The conductive element bundle can be twisted through 360° in the inactive region. This twisting may not alter the spatial arrangement of the conductive elements. MA / t / zuzz / uouy / y inactive region, but can reduce the volume associated with winding. The stator may be a multi-phase stator. The slotless phase winding may be a first slotless phase winding, and the stator is a multi-phase slotless stator comprising a plurality of slotless phase windings. Each of the pluralities of slotless phase windings may be a phase winding of the type described above. The first active segment of the first slotless phase winding may be offset from the second active segment of the first slotless phase winding in the active region. Each of the pluralities of slotless phase windings may be arranged in a serpentine structure. The serpentine structure of the first slotless phase winding may be intertwined with the serpentine structure of one or more of the other slotless phase windings of the stator. For example, each of the phase windings may be arranged in a repeating serpentine structure around the stator.The repetitive structure of each phase winding can be offset with respect to the structure of other phase windings, so that all can be provided in the stator without overlapping the conductive elements of the different phase windings in the active region. A first active segment of a second phase winding without slots can be arranged between the first and second active segments of the first phase winding without slots. An inactive segment of the second phase winding without slots can be coupled to the first active segment of the second phase winding without slots. The inactive segment of the second phase winding without slots can include a twist provided in the second inactive region, and at least one of the conductive elements of the second phase winding without slots can be twisted in the second inactive region. The stator can be arranged to allow the conductive elements of the first phase winding without slots to pass through the conductive elements of the second phase winding without slots. The second active segment of the first phase winding without slots can be located in the active region between the first and second active segments of the second phase winding without slots. The conductive elements of the first phase winding without slots can be arranged adjacent to the conductive elements of the second phase winding without slots. The first phase winding without slots can be provided with the same twist as the second phase winding without slots. For example, the change in configuration / orientation of the conductive elements of the first phase winding between its first and second active segments can be the same as the change in configuration / orientation of the conductive elements of the second phase winding between its first and second active segments.A first active segment of a third phase winding without slots can be provided in the active region between the first and second active segments of the first phase winding without slots. Both the second and third phase windings can be the same as the first winding. Additional phase windings can also be provided. The aspects of this disclosure may provide an electrical machine comprising: a stator as disclosed herein and a rotor carrying a plurality of magnets. The electrical machine is arranged such that the magnets carried by the rotor are aligned with the active region of the stator. The electrical machine may comprise a motor and / or a generator, as described herein. The distance of an air gap between the rotor magnets and the active region of the stator may be less than the cross-sectional depth of the plurality of conductive elements of the slotless phase winding. For example, the depth of the conductive element bundle may be greater than the air gap. The depth of the conductive elements may be large relative to the air gap.For example, the conductive elements can fill at least half of the magnetic gap, or more than 60%. A flux ring can be provided behind the phase winding (e.g., away from the rotor). The flux ring can be configured to close the magnetic field circle. The magnetic gap can comprise the separation distance between the flux ring (e.g., its inner surface) and the rotor's permanent magnets (e.g., its outer surface). The flux ring can have a depth similar to the depth of the magnetic air gap. For example, the depth of the flux ring can be substantially the same, if not greater. For example, the air gap can be less than 1 mm, such as less than 0.6 mm. Brief description of the drawings Some examples from this disclosure will now be described by way of example only, with reference to the figures, in which: Figure 1 shows a schematic diagram of an electrical machine with a stator and a rotor. Figure 2 shows a schematic diagram of a stator winding. Figure 3 shows a schematic diagram of a stator winding. Figure 4 shows a schematic diagram of a stator winding. Figure 5 shows a schematic diagram of a stator winding. Figure 6 shows a schematic diagram of a stator winding. Figure 7 shows a schematic diagram of a stator winding. Figure 8 shows a schematic diagram of a stator winding. Figure 9 shows a schematic diagram of a stator winding. Figure 10 shows a schematic diagram of a stator winding. Figure 11 shows a schematic diagram of a stator winding. Figure 12 shows a schematic diagram of a stator winding. Figure 13 shows a schematic diagram of a stator winding. Figure 14 shows a schematic diagram of a radial space electric machine. Figure 15 shows a schematic diagram of a step in a method of manufacturing a stator winding. Figure 16 shows a schematic diagram of a stator winding. Figure 17 shows a schematic diagram of a stator winding. Figure 18 shows a schematic diagram of a step in a method of manufacturing a stator winding. Figure 19 shows a schematic diagram of cross-sections of rear active segments. MA / t / zuzz / uouy / y Figure 20 shows a schematic diagram of cross-sections of rear active segments. In the drawings, similar reference numbers are used to indicate similar elements. Detailed Description of the Invention The modalities of this disclosure pertain to stators for electrical machines. In particular, a stator is provided with one or more phase windings. The phase windings are arranged with insulated conductors that are bent and twisted in inactive regions of the stator. The conductors may be straight and untwisted through the active region of the stator. The conductors are then twisted and bent in the inactive region, changing the arrangement and / or orientation of the conductors. The distribution of the conductive elements will vary depending on the active region of the stator. This can lead to a more uniform field distribution within the stator and can also reduce circulating voltage losses when the stator is operating. Figure 1 shows an electric machine 1. The top part of Figure 1 is a cross-sectional view of the electric machine (e.g., in a plane passing through an axis of rotation). The bottom part of Figure 1 is a cross-sectional view of the electric machine in plane AB. The electric machine includes a stator 10 and a rotor 2. An air gap 9 is provided between the rotor 2 and the stator. The stator 10 includes a phase winding 7 and a flux ring 8. The stator 10 has an active region, and first and second inactive regions. An active segment 71 is shown in the active region. A first inactive segment 72 is shown in the first inactive region and a second inactive segment 73 is shown in the second inactive region. The rotor 2 has a central shaft 21, a coupling element 22 and a plurality of permanent magnets 6. Electric machine 1 includes a housing 4 with a bearing assembly 3. Housing 4 includes a mounting plate 5. In the example in Figure 1, electrical machine 1 is a radial space machine. Electrical machine 1 can be a motor, in which case the stator 10 can be used to drive the rotation of rotor 2, and / or it can be a generator, in which case the stator 10 can be used to harness the electrical energy generated by the rotation of rotor 2. The stator 10 and the rotor 2 are housed within the casing 4. The casing 4 and the mounting plate 5 surround the stator 10 and the rotor 2 to accommodate these components. The electrical machine 1 is symmetrical about a central axis; the central axis is the axis of rotation of the rotor 2. The rotor 2 is provided radially within the stator 10 (and the housing 4). The rotor 2's central shaft 21 extends along the central axis (the axis of rotation of the rotor 2). The central shaft 21 is coupled to the housing 4 via the bearing assembly 3. The bearing assembly 3 may consist of two bearing assemblies. A first bearing assembly 3 is provided at a first end of the central shaft 21 (where the shaft is surrounded by the housing 4). A second bearing assembly 3 is provided at a second region of the central shaft 21 away from the first end (where the shaft passes through the mounting plate 5). The mounting plate 5 is coupled to the shaft radially outward from the central shaft 21 (and the stator 10). The coupling element 22 extends radially outwards from the shaft to provide an external cylindrical drum for the rotor 2. Permanent magnets 6 are provided on the rotor drum.The stator 10 is located radially outward from the rotor 2. The air gap 9 is provided as the radial space between the permanent magnets 6 and the phase winding 7. The rotor 2 is cylindrical (e.g., the permanent magnets 6 are provided on a cylindrical surface). The stator 10 is cylindrical and hollow (e.g., the phase winding 7 is provided on a cylindrical surface). The cylindrical surface of the magnets 6 and the phase winding 7 are separated by a cylindrical air gap 9. The windings are provided on a mounting surface of the stator 10. The mounting surface is located radially outward from the windings so that they are oriented inward (toward the magnets 6 of the rotor 2). The stator winding 7 is circumscribed by the flux ring 8. In other words, the flux ring 8 is arranged radially outward from the phase winding 7. The flux ring 8 is provided in the active region of the stator 10.The housing 4 is provided radially outwards from the flow ring 8, to accommodate all components within it. With rotor 2 inserted into stator 10, the permanent magnets 6 of rotor 2 are aligned with the active region of stator 10. The permanent magnets 6 are located radially into the active region of stator 10. The active region of stator 10 extends along the length of the permanent magnets 6 in a direction parallel to the axis of rotation of rotor 2. Thus, there are permanent magnets 6 located radially within the active region of stator 10. There are no permanent magnets 6 located radially within the inactive region of stator 10. Therefore, the magnetic field in the active region is much greater than in the inactive region of stator 10. The inactive regions are outside the longitudinal length of the permanent magnets 6. The inactive regions are separated by the active region.In other words, a cylindrical surface of the stator 10 provides the active region, and the regions on either side of that cylindrical surface (along its axial length) are inactive regions. The phase winding 7 rotates in the idle region so that it can return to the active region. In the first idle region, the first idle segment 72 extends radially outward as it rotates. The winding 7 in the first idle region can extend radially farther from the axis of rotation of rotor 2 than the winding 7 in the active region. An inner surface of the first idle segment 72 can be located at the same distance from the axis of rotation as an inner surface of the first active segment 71. An outer surface of the first idle segment 72 can be located farther from the axis of rotation compared to an outer surface of the first active segment 71. The first idle segment 72 can curve radially outward as it rotates through 180° to return to the active region. In the second idle region, the second idle segment 73 extends radially inward as it rotates. The second idle segment 73 can extend toward the axis of rotation in ML / t / zuzz / uouy / y a hollow region of the housing 4 of rotor 2. An inner surface of the second inactive segment 73 can be located closer to the axis of rotation of rotor 2 compared to an inner surface of the active segment 71. The second inactive segment 73 can curve radially inward as it rotates through 180° to return to the second active region. In the region of the active segment 71 and the second inactive segment 73, the housing 4 can be cylindrical. The housing 4 can taper radially outward in the region of the first inactive segment 72. The first and second inactive segments can be radially adjusted within the housing 4 in regions outside the longitudinal extension of the magnets 6 in rotor 2. The rotor 2 is configured to rotate about its axis of rotation. The bearing assembly 3 is configured to allow the rotor 2 to rotate (e.g., about its axis of rotation) relative to the stator 10 (and the housing 4). Therefore, the permanent magnets 6 of the rotor 2 can move (rotate) relative to the phase winding 7 of the stator 10. The active segments of the phase winding 7 are arranged to extend across the active region of the stator 10. The active segments can extend in a straight direction parallel to the axis of rotation of the rotor 2. The inactive segments are arranged to couple adjacent active segments so that each active segment 71 can extend in a straight direction across the active region. Each adjacent active segment 71 will extend across the active region in the opposite direction (e.g., from the first to the second inactive region, then from the second to the first inactive region). The active segments can be provided across 360° of the active region of the stator 10. The inactive segments can be arranged to allow straight active segments to extend across the entire active region of the stator 10. In some or all of the idle regions, the idle segments may be twisted. For example, the phase 7 winding may twist as it rotates in one or more of the idle regions. The twist of the phase 7 winding will now be described with reference to the following figures. The top of Figure 2 shows an enlarged cross-sectional view of the stator phase windings 10. The bottom of Figure 2 shows a reduced view of a portion of an electrical machine 1 from which the enlarged view is taken. In the example in Figure 2, stator 10 has three phase windings. As shown, there is a first phase winding denoted as I', a second phase winding denoted as JI', and a third phase winding denoted as JII'. The top of Figure 2 shows a cross-section in the active region of stator 10. Two active segments are shown for each of the phase windings. Each phase segment has one active segment 71 on the left side of the centerline and one on the right side of the centerline. One active segment 71 of each phase winding on the right side is denoted by 71-1, 71-11, and 71-111, respectively. The phase windings are arranged in order. This order is repeated with each subsequent active region (e.g., I, II, III). In other words, the three phase windings are intertwined. The three phase windings extend around the entire active region of stator 10.As they spread around, they remain in a fixed phase offset from each other (e.g., they trace the same shape as they spread around the region). MA / t / zuzz / uouy / y active). Reference numbers 61 and 62 show the different pole directions for the different active segments. As can be seen, between a first active segment 71 and a subsequent active segment 71 for each of the phase windings, the pole direction has changed (for example, since the current-carrying elements have now rotated 180°). In addition to rotating 180° in an idle region, the phase winding can also be twisted in the idle region. An example of such twisting will now be described with reference to Figure 3. Figure 3 shows a schematic of a phase winding. In the central portion of Figure 3, a diagram shows the shape a phase winding can take as it extends around the stator 10. As can be seen, Figure 3 shows a flattened view, but for a radially spaced stator, the surface would be cylindrical. The phase winding includes a series of active segments 71 in the active region of the stator 10. The dashed lines along the figure show where the active region is located. Above and below these dashed lines are the inactive regions. The first inactive region is shown at the bottom of the figure with the first inactive segments 72, and the second inactive region is shown at the top of the figure with the second inactive segments 73. The phase winding consists of a plurality of conductive elements. Each conductive element comprises a conductor (e.g., copper wire) surrounded by an electrically insulating sheath. Within a phase winding, there may be a plurality of such conductive elements. The conductive elements may be arranged together into a conductive element assembly. The active segments extend across the active region of the stator 10 from one inactive region to the other. The active segments extend across the active region in alternating directions from one active segment 71 to the next. Each time the active segments extend across the active region, they extend directly across it. For a radially spaced stator 10, these active segments will extend across the active region parallel to the axis of rotation. The active segments are all parallel to each other. The bundle of conducting elements can have the same shape (in cross-section) for each active segment 71. However, the arrangement of the conducting elements within that bundle can change as the bundle is twisted. The inactive segments in the first inactive region are all identical. These first inactive segments 72a have no twist in the first inactive region. As can be seen, as the bundle of conducting elements enters the first inactive region from the active region, the bundle twists 180° toward the active region. As the bundle twists, the conducting elements that start on the outside of the twist remain on the outside of the twist all the way around and back to the active region. Likewise, the conducting elements on the inside of the twist remain on the inside of the twist. As can be seen in Figure 3, the leftmost conducting elements on the way to the first inactive region exit the first inactive region back to the active region as the rightmost conducting elements. Similarly, the rightmost elements at the entrance exit as the leftmost elements. MA / t / zuzz / uouy / y In this respect, when observing a cross-section of active segment 71 before and after passing through the first inactive region, the arrangement of the conductive elements within the bundle will be the same. That is, when observing the cross-section in a direction opposite to the direction in which the conductive elements extend (e.g., opposite to the direction of current flow). When observing the cross-section of adjacent active segments before and after turning in the first inactive region in the same plane (i.e., observing both cross-sections from the same direction), one active segment 71 will be a mirror image of the other (approximately a plane perpendicular to the separation distance between the two active segments). In the second inactive region, three different arrangements for the second inactive segments are shown. These include an untwisted second inactive segment 73.a, a half-twisted second inactive segment 73.c, and a quadri-twisted second inactive segment 73.d. The second non-twisted inactive segment 73.a is the same as the non-twisted segments shown in the first inactive region. The second half-twisted idle segment 73.c has a twist so that the arrangement of the conducting elements within the bundle changes as it moves through the second idle region. In this example, the bundle of conducting elements is twisted so that the leftmost conducting elements entering the second idle region also exit the second idle region as the leftmost conducting elements. Similarly, the rightmost conducting elements at the entrance are the rightmost conducting elements at the exit. Therefore, when viewed from the same plane and in the same direction, the elements at the exit and entrance will appear identical. However, when viewed from the same plane but in the opposite direction to the current flow, they will be a mirror image across the centerline. The second quad-twisted idle segment 73.d has a twist so that the arrangement of the conducting elements within the bundle changes as it moves through the second idle region. In this example, the bundle of conducting elements is twisted so that the elements enter aligned in a plane parallel to the stator surface 10 and exit aligned in a plane perpendicular to the stator surface 10. In other words, the elements at the exit have been rotated approximately 90° relative to the elements at the entrance. As such, the active segments will be straight and untwisted, and will be positioned parallel to each other. However, the arrangement of the conductive elements within the active segments will change. In particular, as the conductive elements pass through the second semi- and quad-twisted inactive segments, the arrangement of the conductive elements within the bundle will change (e.g., relative to the magnets 6 on rotor 2). Consequently, for at least one of the conductive elements, that element will be closer to or farther from the magnets 6 on rotor 2 in adjacent active segments that have been coupled together through an inactive segment with an inward twist. The conductive elements may or may not have the same length in the inactive regions. In the example shown in Figure 3, the black rectangles shown in the cross-sectional views above and below the main winding shape diagram represent The first turn of a 4-turn phase winding is shown in the rectangle, and the other white rectangles represent the other 3 turns. The position of the first black turn changes depending on the type of bending and twisting in the inactive regions. This allows the voltage integral along the entire active region of stator 10 in all conducting elements of the phase winding to minimize circulating voltage losses. The upper portion of Figure 4 shows a cross-sectional view of a stator 10 including a phase winding (e.g., in a plane passing through the axis of rotation). The lower portion of Figure 4 shows a cross-sectional view in the CD plane (in the active region of the stator 10). In this example, the stator 10 is a three-phase, sixteen-pole winding. Figure 4 shows stator 10 with three phase windings. As can be seen, the stator winding is straight in the active region, but not straight in the first and second inactive regions. As with the stator 10 described earlier, the first inactive segments comprise a turn that extends radially outward in the first inactive region. The second inactive segments comprise a turn that extends radially inward in the second inactive region. The three phase windings are parallel in the active region. The three phase windings are not parallel in the inactive region. Instead, the phase windings are arranged in a staggered formation so that each phase winding can pass through other phase windings in the inactive region to maintain the phase winding arrangement in the active region (e.g., I, II, III, I, II, III).For example, each idler segment can extend radially inward or outward to provide a three-dimensional twist. Each idler segment can pass within the three-dimensional fold of one or more idler segments. The upper portion of Figure 5 shows a magnified view of a phase winding of a stator 10, and the lower portion of Figure 5 shows a further magnified view of the phase winding of stator 10. The cross-section is taken in an active region of stator 10. In the example in Figure 5, the stator 10 also includes one or more winding support structures. The winding support structures are configured to mechanically support conductive elements of each phase winding. The support structures can be configured to hold a bundle of conductive elements together (for example, in a parallel configuration). The support structures can include a bundle support structure 76. The bundle support structure 76 is arranged to surround each phase winding to maintain the phase winding in a selected cross-sectional shape.The support structure of package 76 can hold the active segments of single-phase winding in a parallel arrangement with each other. The upper part of Figure 6 shows a schematic diagram to illustrate exemplary changes in the phase windings of a stator 10. The lower part of Figure 6 shows an enlarged view of a region from the upper part of Figure 6. The cross-section of Figure 6 is in the active region of the stator 10. Figure 6 shows a stator 10 with three phase windings. Four active segments (SX, S1, S2, and S3) are shown. Each of the three phase windings has four turns (e.g., elements ML / t / zuzz / uouy / y conductors) per phase. Each of these turns is indicated as 'a', 'b', 'c', and 'd' to show how its arrangement changes between adjacent segments (due to torsion in the inactive region). To illustrate this, the first turn d for the first phase winding is shown as a black rectangle. As can be seen, the arrangement of the phase windings changes between sectors S1 and S2 and between sections S2 and S3. The active segments 71,X-I, 71.X-II, and 71.X-II are shown to illustrate how the arrangement changes between adjacent active segments. The upper portion of Figure 7 shows a schematic diagram illustrating exemplary changes in the phase windings of a stator 10. The lower portion of Figure 7 also shows a schematic diagram illustrating exemplary changes in the phase windings of a stator 10, but in a later region of the stator 10. The cross-section in Figure 7 is in the active region of the stator 10. Again, two adjacent active segments, Sn and Sn+1, are shown. Each of the three phase windings has four turns, a, b, c, and d (e.g., conducting elements or groups of conducting elements). The four turns can form the winding bundle. As can be seen, the arrangement within the active segments for a phase winding changes between adjacent segments.The three phase windings remain in order (I, II, III, I, II, III), but the internal arrangement of at least one of the phase windings changes between adjacent active segments. For example, the internal arrangement of each winding changes from a, b, c, d, c, b, a. The upper portion of Figure 8 shows a cross-sectional view of a stator 10 including a phase winding (e.g., in a plane passing through the axis of rotation). The lower portion of Figure 8 shows a cross-sectional view in plane CD (in the active region of the stator 10). One phase winding is shown, although more may be provided. The winding may have a support structure in the inactive regions (shown by black fill). An inner side of the active region may have a winding support structure 76. The winding support structure 76 may comprise a covering, such as a polymer coating. The winding support structure 76 may be configured to support the phase windings to hold them in place on a mounting surface of the stator 10. Figures 9 to 11 show schematic diagrams of exemplary phase winding arrangements for a stator 10.Figure 9 shows a stator region 10 with three phase windings. Again, the view is planar, but for a radial space, this would be on the surface of a cylinder. As shown, the three phase windings interlock with each other in a repeating pattern. The active segments are adjacent and parallel. The inactive segments are arranged to maintain the interlocking pattern of the three phase windings. For example, in inactive regions, the phase windings may be bent into a three-dimensional pattern to allow them to pass through gaps in adjacent phase windings. Figure 10 illustrates one exemplary arrangement where the inactive segments extend radially inward / outward so that adjacent segments can pass through each other to return to the active region. Different bending patterns may exist for different inactive segments.The repetitive pattern of the active segments (I, II, III) is. The ML / t / zuzz / uouy / y pattern is maintained, and the twist in the idle segments is arranged to allow this pattern to be maintained with the individual idle segments passing each other in the idle regions. The three-dimensional bending in the idle region can allow for a reduction in the longitudinal extension of the phase winding (e.g., to occupy less volume within the housing 4). This can improve thermal conductivity, as well as reduce size. Figure 11 shows a stator 10 with different types of twist in the idle region. For example, as the twists in the idle region move radially inward / outward, there can also be twists in these regions (and these twists can be different). For example, quadri- and / or semi-twists can be provided. Furthermore, adjacent segments can have different twists in the same idle region. Figures 12 and 13 show a schematic diagram of a phase winding arrangement for a stator 10. The examples described above have been directed to radially spaced electrical machines. This disclosure can also be extended to axially spaced electrical machines. In this case, the stator 10 and rotor 2 will not be cylindrically separated from each other, and instead, the stator 10 and rotor 2 may be axially offset cylinders. The phase winding will instead be provided on a circular surface of the cylinder (rather than on a cylindrical surface). As a result, the phase windings extend radially inward and outward on the flat circular surface (rather than on the cylindrical surface that lies parallel to the axis of rotation). Figures 12 and 13 illustrate this arrangement. The active region of stator 10 is an annular region. The region radially inward from the ring is the first inactive region, and the region radially outward from the ring is the second inactive region. The phase windings extend across the active regions between the first and second inactive regions. As shown, the windings and phase segments are more closely packed in the inner region than in the outer region. Adjacent active segments are not parallel, but they would all intersect at the center of the circle if they continued in a straight line that far. Figures 12 and 13 also show the X and Y terminal ends for each of the three phase windings. The terminal ends are for coupling the phase windings to a power source (for a motor) or for collecting the generated power (for a generator).Figure 13 shows a similar arrangement to Figure 12 but with three-dimensional turns in the inactive regions, so that the inactive segments can pass each other when returning to the active region. Figure 14 shows an electric machine 1. The upper part of Figure 14 is a cross-sectional view of the electric machine 1 (e.g., in a plane passing through an axis of rotation). The lower part of Figure 14 is a cross-sectional view in plane AB. The electric machine 1 is similar to that in Figure 1 except that the rotor 2 is shown with a spoke coupling 24 to couple the central shaft 21 to a rotor drum 23 where the permanent magnets 6 are provided. One or more holes may be provided in the housing 4 to pass the stator terminal wires 10 through the housing 4. Figure 15 shows a step in a method of manufacturing a phase winding. Figure 15 shows an intermediate step of an exemplary production method for manufacturing MA / t / zuzz / uouy / y of a phase winding of the present disclosure. The phase winding includes a plurality of active segments 181 and inactive segments 182, 183. Terminal conductors 184 for connecting the stator winding to an external component, such as a power supply (for the motor) or a power collector (for the generator), are also shown. The active segments 181 of the phase winding are straight and are formed by parallel conductive elements. For example, clamping and / or encapsulation tools covering only the active area segments 181 may be used, or additive manufacturing of conductive elements may be provided to provide a parallel arrangement of conductive elements by means of fastening or fastening materials, such as baking enamel, polymer, or ultraviolet (UV) light-curing resin, etc.The shape of the cross-section and / or the curvature of the inactive regions may differ. The inactive areas may then be bent to provide a serpentine arrangement of the active areas, as shown in the previous figures. The conductive elements may be molded and / or fused into the active regions (for example, to provide a bundle). Figure 16 shows a schematic diagram of a phase winding where each of the active segments 181 is arranged in one of two configurations: an 'up' configuration (shown by reference numbers 181u) and a 'down' configuration (shown by reference numbers 181d). As shown, the inactive segments are divided into: (i) twisted inactive segments 185 in which the conducting elements are bent into the active region with a twist, and (ii) untwisted inactive segments 187 in which the conducting elements are simply bent into the active region without twisting. As shown, the two twisted inactive segments 185 are evenly distributed (i.e., opposite each other). Therefore, in one half, the active segments are in the up configuration, and in the other half, in the down configuration. Figure 17 shows an arrangement similar to that in Figure 16, except that there is only one twisted inactive segment 185 in the winding of Figure 17. The twisted inactive segment 185 is on one side of the phase winding opposite the terminal conductors 184. Half of the active segments are in the upward configuration and the other half in the downward configuration. Some or all of the untwisted inactive segments may be replaced by inactive segments in which the conducting elements (or bundle of conducting elements) are twisted through 360° so that they are in the same configuration as adjacent active segments, despite being twisted at the inactive segment separating those two active segments. Such an arrangement may reduce the volume requirements for the phase winding. Figure 18 shows a schematic diagram of a step in a method for manufacturing a stator winding. In particular, Figure 18 shows a potential intermediate step in the manufacturing process of a phase winding with more than one turn per phase. Figure 18 shows an active region 171, as well as a first inactive region 172 and a second inactive region 173. The phase winding includes two twisted inactive segments 185 that are twisted, but not 360° (e.g., inactive segments in which partial twist is provided). The remaining inactive segments are 360° twisted inactive segments 186 (although, of course, these could be provided by inactive segments that are twisted 720° or higher multiples of 360°, and / or inactive segments without twists).The number of active segments in each configuration is the same (for example, the partial turns are distributed around the winding so that the number of active segments in one configuration is balanced by the number in an opposite configuration, such as the up-and-down distribution in Figures 16 and 17). Figure 19 shows a further series of cross-sections through four active segments 181. The phase winding comprises a plurality of conductive elements 191 arranged in a bundle. In this example, the bundle is arranged in a rectangular shape, but other arrangements could be used. 160 conductive elements 191 are shown in four turns (T1, T2, T3, and T4). To illustrate the different changes in arrangement, a first layer FL and a last layer LL are indicated. As can be observed, between 'a' and 'b', no twist is provided while the bundle rotates in the idle segment. As such, the order is reversed (from T1 to T4 to T4 to T1), and the first and last layers remain the same as they were. This is a non-twisting turn 187. Between 'b' and 'c', a 180° twist is provided while the bundle rotates in the idle segment. As such, the order and layers are reversed. That is, the four turns change order again, and the first and last layers have changed. This is a 180° twisting turn 185. Between 'c' and 'd', a corresponding change occurs in that between 'a' and 'b', only the layers remain (so that the first and last layers are different compared to the first non-twisting turn 187). Figure 20 shows an arrangement similar to that in Figure 19. Three layers are shown in Figure 20 (T1, T2, T3). Between 'a' and 'b', a 180° twist is provided while the inactive segment rotates. As such, the order of the twists is reversed, as is the order of the layers. Between 'b' and 'c', no twist is provided, so the order of the twists changes, but the order of the layers remains the same. Between 'c' and 'd', a 360° twist is provided. As can be seen, the twists again reverse order, but the order of the layers remains the same. This is a 360° 186 twist. With reference to the darker rectangle (with filled circles), you can see how the position of the conductive elements within the bundle changes. These changes are controlled to minimize the voltage integral associated with the phase winding. It will be apparent from the preceding analysis that the examples shown in the figures are merely illustrative and include features that can be generalized, eliminated, or replaced as described herein and as set forth in the claims. With reference to the drawings in general, it will be apparent that the schematic functional block diagrams are used to indicate the functionality of the systems and apparatus described herein. As those skilled in the subject matter of this disclosure will appreciate, each of the examples described herein can be implemented in a variety of ways. Any feature of any aspect of the disclosure can be combined with any of the other aspects of the disclosure. For example, aspects of the method can be combined with aspects of the apparatus, and features described with reference to the operation of particular elements of the apparatus can be provided in methods that do not use those particular types of apparatus. Furthermore, each of the features of each example is intended to be separable from the features with which it is described in combination, unless it is expressly stated that some other feature is essential to its operation.Each of these separable features may, of course, be combined with any of the other features of the examples in which it is described, or with any of the other features or combination of features of any of the other examples described herein. Furthermore, equivalents and modifications not described above may also be employed without departing from the invention. Other examples and variations of the disclosure will be apparent to those skilled in the art of this disclosure.

Claims

1. A stator for interacting with magnets carried by a rotor of an electric machine, the stator comprising: an active region arranged to align with the magnets carried by the rotor; a first inactive region and a second inactive region, wherein the first and second inactive regions are separated by the active region; and a slotless phase winding comprising a plurality of conducting elements, wherein each conducting element comprises a conductor provided in an insulating housing, and wherein the slotless phase winding is arranged in a serpentine structure comprising: a first active segment in which the conducting elements extend throughout the active region from the first inactive region to the second inactive region; a second active segment in which the conducting elements extend throughout the active region from the second inactive region to the first inactive region;and an inactive segment coupling the first active segment to the second active segment, wherein the inactive segment comprises a proportionate twist in the second inactive region, and wherein at least one of the conducting elements is twisted in the second inactive region.; 2. The stator according to claim 1, wherein the plurality of conducting elements are substantially parallel to each other in the first and / or second active segment.

3. The stator according to any preceding claim, wherein the conducting elements in the first active segment are substantially parallel to the conducting elements in the second active segment.

4. The stator according to any preceding claim, wherein the conducting elements extend straight and untwisted through the active region.

5. The stator according to any preceding claim, wherein the slotless phase winding is a first slotless phase winding, and wherein the stator is a multi-phase slotless stator comprising a plurality of slotless phase windings.

6. The stator according to claim 5, wherein the first active segment of the first phase winding without slots is compensated by the second active segment of the first phase winding without slots in the active region.

7. The stator according to claim 6, wherein each of the plurality of slotless phase windings is arranged in a serpentine structure.

8. The stator according to claim 7, wherein the serpentine structure of the first slotless phase winding is intertwined with the serpentine structure of one or more of the other slotless phase windings of the stator.

9. The stator according to claim 8, wherein a first active segment of a second slotless phase winding is arranged between the first and second active segments of the first slotless phase winding. MA / t / zuzz / uouy / y 10. The stator according to claim 9, wherein an inactive segment of the second phase winding without slots is coupled to the first active segment of the second phase winding without slots; and wherein the inactive segment of the second phase winding without slots comprises a proportionate twist in the second inactive region, and wherein at least one of the conducting elements of the second phase winding without slots is twisted in the second inactive region.

11. The stator according to claim 10, wherein the stator is arranged to allow the conducting elements of the first slotless phase winding to pass through the rotation of the second slotless phase winding.

12. The stator according to claim 11, wherein the second active segment of the first slotless phase winding is arranged in the active region between the first and second active segment of the second slotless phase winding.

13. The stator according to any of claims 10 to 12, wherein the rotation of the first slotless phase winding is arranged adjacent to the rotation of the second slotless phase winding.

14. The stator according to any of claims 10 to 13, wherein the first slotless phase winding is provided with the same spin as the second slotless phase winding.

15. The stator according to any of claims 5 to 14, wherein a first active segment of a third phase winding without slots is provided in the active region between the first and second active segment of the first phase winding without slots.

16. The stator according to any preceding claim, wherein the inactive segment of the serpentine structure of the slotless phase winding is a first inactive segment, and wherein the serpentine structure of the slotless phase winding further comprises a second inactive segment and a third active segment; and wherein the second inactive segment couples the second active segment to the third active segment, and wherein the second inactive segment comprises a proportionate twist in the first inactive region.

17. The stator according to claim 16, wherein at least one of the conducting elements is twisted in the first inactive region.

18. The stator according to claim 17, wherein the torsion in the first inactive region comprises a half-torsion, and the rotation in the second inactive region also comprises a half-torsion.

19. The stator according to any preceding claim, wherein the conducting filaments of the slotless phase winding are packed into a fiber bundle, and wherein the fiber bundle has an orthogonal or hexagonal cross-sectional shape.

20. The stator according to any of the preceding claims, wherein the conductor of each conducting element is rectangular, circular, or hexagonal in cross-section.

21. The stator according to any preceding claim, wherein the stator is arranged to provide a radial air gap between the stator and the rotor; and wherein the active segments of the slotless phase winding extend in an axial direction parallel to an axis of rotation of the rotor.

22. The stator according to any of claims 1 to 20, wherein the stator is arranged to provide an axial air gap between the stator and the rotor; and wherein the active segments of the slotless phase winding extend in a radial direction orthogonal to the axis of rotation of the rotor.

23. The stator according to any of the preceding claims, wherein at least one of: the stator is for interacting with magnets carried by a rotor of an electric motor, and wherein the stator is configured to apply current to the slotless phase winding to drive the rotation of the rotor of the electric motor; and the stator is for interacting with magnets carried by a rotor of a generator, and wherein the stator is configured to harness the energy of a resultant current generated in the slotless phase winding in response to the rotation of the magnets of the generator rotor.

24. An electric machine comprising: the stator of any of the preceding claims; and a rotor carrying a plurality of magnets; wherein the electric machine is arranged so that the magnets carried by the rotor are aligned with the active region of the stator.

25. The electric machine according to claim 24, wherein an air gap distance between the rotor hands and the active region of the stator is less than a cross-sectional depth of the plurality of conducting elements of the slotless phase winding.

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