Coil structure

Abstract

A coil structure for a stator of an electric motor having a rotor configured to rotate about an axis. The coil structure comprises a conductor configured to provide a coil; the coil comprising one or more turns of wire around a magnetic core of the stator to induce a magnetic flux in the magnetic core when in use. The conductor comprises one or more first portions comprising a plurality of sub-conductors in parallel with each other; and one or more second portions coupled in series with the one or more first portions. Each of the one or more second portions comprises a single sub-conductor or a smaller number of sub-conductors in parallel; and at least one coil comprises one of the one or more first portions and one of the one or more second portions. The transition between the first and second portions occurs at both axial outer ends of the magnetic core. The invention provides optimal use of the copper area in order to provide as low resistance as possible over the entire operating frequency range of the machine and provides a method of manufacturing electric motors and transformers that are effective over a wide frequency range.

Description

Technical Field

[0001] This invention relates to coil structures, such as stator windings of electric motors. Background Technology

[0002] A typical synchronous motor consists of a stationary stator with coil windings magnetically coupled to and around the rotor. Typically, such a motor is powered by three-phase alternating current that synchronously switches the polarity of electromagnets in the stator to generate torque.

[0003] In high-frequency alternating current (AC) electromagnetic machinery, the losses in the electrical windings caused by the high AC frequency are several orders of magnitude higher than the losses in the same windings when using DC current or low-frequency current. Such electromagnetic machinery and inductor windings are typically wound with Litz wire. Litz wire is a bundle of smaller conductors with multiple thin wires, each insulated from the others and twisted in a way that minimizes the increase in resistance due to increasing frequency. Because the total copper area of ​​multiple conductors or strands is smaller compared to a solid conductor of the same outer diameter, the DC resistance of Litz wire is higher than that of a single conductor of the same size. However, as the frequency increases, the resistance of Litz wire does not increase rapidly due to the reduced AC effect. At electrical frequencies above a few kHz, Litz wire provides a more efficient conductor. Summary of the Invention

[0004] According to a first aspect of the invention, a coil structure for an electromagnetic device is provided, the coil structure comprising a conductor configured to provide a coil including one or more coil turns surrounding a magnetic core to induce a magnetic flux in the magnetic core during use. The conductor includes one or more first portions comprising a plurality of parallel sub-conductors, and one or more second portions coupled in series with the first portions, wherein the second portions or each of the second portions comprises a single sub-conductor or a smaller number of parallel sub-conductors. Thus, the conductor can be changed from a Litz wire having multiple sub-conductors in one portion of the coil to a single sub-conductor in another portion. This variation in the number of sub-conductors can be configured to occur even in a single turn of the coil to improve performance. That is, each coil turn may include a first portion of one or more first portions and a second portion of one or more second portions.

[0005] The aforementioned coil structure can be configured for the stator of an electric motor having a rotor configured to rotate about an axis. At least one coil turn may include one or more first portions and one or more second portions, wherein the transition between the first and second portions occurs substantially at the two axially outer ends of the core. Typically, the first portion is aligned axially with the stator core, transitioning to the second portion (e.g., a single sub-conductor) as it exits a slot at either end of the core. Thus, in this embodiment, the first portion of the conductor is located in the active region of the stator, while the second portion of the conductor, constituting the end winding of the coil, is located outside the active region.

[0006] The first section, or the multiple sub-conductors of each first section, may include multiple sub-conductors ranging from 2 to 10. Surprisingly, a relatively small number of parallel sub-conductors has been found to provide good results.

[0007] Preferably, the sub-conductors of the first section or each first section are intertwined (e.g., they have a helical shape). Typically, the sub-conductors are twisted about an axis (imaginary line) perpendicular to the cross-sectional profile of the conductor. The axis is typically located between the center point of the cross-sectional profile and the outer edge of the cross-sectional profile, and can be centered or off-center. The multiple sub-conductors of the first section or each first section are preferably twisted to provide one or more complete rotations for each sub-conductor. This allows each sub-conductor to have substantially equal magnetic field exposure. In embodiments, the number of turns can also be close to an integer. For example, each sub-conductor may include between 90% and 100% of a full turn, or one or more full turns and up to 10% additional turns. The sub-conductors of the first section or each first section may be braided together.

[0008] The conductors can be configured to couple the first and second portions through a single sub-conductor. The coil structure may include multiple said conductors to provide corresponding multiple coils (e.g., each stator slot of an electric motor has one coil).

[0009] According to a second aspect of this disclosure, an electromagnetic device is provided, including a coil structure according to the first aspect described above. The electromagnetic device includes first and second magnetic cores with an air gap between the cores (e.g., a stator core and a rotor core of an electric motor). For the coil or each coil, the coil turns or each coil turn are arranged around the first magnetic core such that the first portion or each first portion of the conductor is closer to the air gap than the second portion or each second portion of the conductor.

[0010] Advantageously, for the coil or each coil, the conductor can be arranged such that when the electromagnetic device is in use, the first portion or each first portion of the conductor experiences a stronger magnetic field than the second portion or each second portion.

[0011] The electromagnetic device can be an electric motor having a stator including the first magnetic core and the coil structure, and a rotor including the second magnetic core. Multiple coils are configured to provide multiple phase windings for the motor. For example, coils can be connected in series and / or in parallel with other coils to provide a three-phase winding. Each coil turn can include a first portion and a second portion, wherein the first portion is located in a slot of the stator adjacent to the air gap, and the second portion provides a return path outside that slot (e.g., for providing a toroidal coil structure). Alternatively, the coil can be wound on stator teeth such that a first portion of the conductor is located near the air gap in two adjacent stator slots, and a second portion is located in the same two stator slots but further away from the air gap, and / or positioned at the top and bottom (end windings) between the stator slots, where AC effects may be lower. The first portions in adjacent stator slots can then be connected by a single sub-conductor (i.e., a non-Litz wire at the top and bottom between two stator slots).

[0012] According to a third aspect of this disclosure, a method is provided for forming a coil structure for an electromagnetic device and including one or more coils. The method includes forming a generally U-shaped portion, forming a top, and securing the top to the generally U-shaped portion to provide a continuous conductor for the coil or each coil, the continuous conductor providing one or more coil turns. The coil turns are completed when the parts are secured together. This method can be used to form the coil structure described above according to the first aspect.

[0013] The steps of forming the generally U-shaped portion may include forming the U-shaped portion by additive manufacturing, and optionally forming the top. For example, the U-shaped portion and the top may be 3D printed separately and then attached together.

[0014] Alternatively, the steps of forming the generally U-shaped conductor portion and optionally the top may include casting one or more of these portions. For example, the mold may be formed by additive manufacturing. The steps of securing the components together may include bonding, welding, or soldering.

[0015] The method may also include inserting a magnetic core (e.g., a stator core) into the generally U-shaped section before fixing the top.

[0016] According to a fourth aspect of this disclosure, a method for forming a coil structure according to the first aspect is provided. The method includes forming the conductor or each conductor by additive manufacturing, and forming an insulating structure between a portion of the conductor or each conductor and its sub-conductors, wherein the insulating structure provides support for the conductor or each conductor during additive manufacturing. For example, the conductor and insulating structure can be formed using a dual-material 3D printing process. The method may further include inserting a magnetic core into the coil structure during conductor formation.

[0017] According to a fifth aspect of this disclosure, a computer-readable storage medium is provided for storing a design document representing the geometric arrangement or shape of a coil structure according to a first aspect.

[0018] According to a sixth aspect of this disclosure, a computer program is provided that includes computer-executable instructions, which, when executed by a processor, cause the processor to control additive manufacturing equipment to manufacture a coil structure according to the first aspect.

[0019] According to a seventh aspect of this disclosure, a method for manufacturing an apparatus by additive manufacturing is provided. The method includes obtaining an electronic file representing the geometry of a coil structure according to a first aspect, and controlling additive manufacturing equipment to manufacture the coil structure according to the geometry specified in the electronic file in one or more additive manufacturing steps.

[0020] According to an eighth aspect of this disclosure, a coil structure for a stator of an electric motor is provided, the motor having a rotor configured to rotate about an axis. The coil structure includes a conductor configured to provide a coil; the coil includes one or more coil turns surrounding a magnetic core of the stator to induce magnetic flux in the magnetic core during use. The conductor includes one or more first portions comprising a plurality of sub-conductors connected in parallel with each other; and one or more second portions coupled in series with the one or more first portions. Each of the one or more second portions includes a single sub-conductor or a smaller number of parallel sub-conductors; and at least one coil includes one of the one or more first portions and one of the one or more second portions. The transition between the first and second portions occurs at two axially outer ends of the magnetic core.

[0021] Preferably, the plurality of sub-conductors in each of one or more first portions comprises a plurality of sub-conductors ranging from 2 to 10.

[0022] Preferably, the sub-conductors of each of one or more of the first portions are intertwined.

[0023] Preferably, multiple sub-conductors of each of one or more first portions are twisted to provide one or more complete rotations of each sub-conductor.

[0024] Preferably, the conductor is configured to couple the first part and the second part through a single sub-conductor.

[0025] Preferably, the coil structure includes a plurality of said conductors to provide a plurality of corresponding coils.

[0026] According to a ninth aspect of this disclosure, an electric motor is provided, including a coil structure according to the eighth aspect above. The electric motor includes a stator core and a rotor core, with an air gap between the two cores. The coil structure includes one or more conductors, each conductor being configured to provide a coil, and for the coil of the one or more conductors, each of the one or more coil turns is arranged around the stator core such that each of one or more first portions of the conductor is closer to the air gap than at least one of one or more second portions of the conductor.

[0027] Preferably, for the coil, the conductor is arranged such that, in use, each of one or more first portions of the conductor experiences a stronger magnetic field than each of one or more second portions during the use of the motor.

[0028] Preferably, the coil structure includes multiple conductors to provide multiple coils, which are configured to provide multiple phase windings.

[0029] Preferably, for each of one or more coil turns, the first portion is located in a slot of the stator adjacent to the air gap, and the second portion provides a return path outside the slot.

[0030] According to a tenth aspect of this disclosure, a method is provided for forming a coil structure for an electric motor, the coil structure including one or more coils. The method includes: forming a U-shaped portion, forming a top, and securing the top to the U-shaped portion to provide a continuous conductor for each of the one or more coils, the continuous conductor providing one or more coil turns.

[0031] Preferably, the step of forming the U-shaped portion includes forming the U-shaped portion by additive manufacturing.

[0032] Preferably, the step of forming the top includes forming the top by additive manufacturing.

[0033] Alternatively, the step of forming the U-shaped portion includes casting the U-shaped portion.

[0034] And, the steps for forming the top, including casting the top.

[0035] In addition, the fixing process also includes bonding, soldering, or flexible soldering.

[0036] Preferably, the method further includes inserting the magnetic core into the U-shaped portion before fixing the top.

[0037] Preferably, the coil structure is the coil structure according to the eighth aspect above.

[0038] According to the eleventh aspect of this disclosure, a method for forming a coil structure according to the eighth aspect above is provided, comprising forming a conductor by additive manufacturing; and forming an insulating structure between a portion of the conductor and its sub-conductors, wherein the insulating structure provides support for the conductor during additive manufacturing.

[0039] Preferably, the conductor and insulating structure are formed by a dual-material 3D printing process.

[0040] Preferably, the method further includes inserting a magnetic core into the coil structure during conductor formation.

[0041] According to a twelfth aspect of this disclosure, a computer-readable storage medium is provided that stores computer-executable instructions thereon. When executed by a processor, the computer-executable instructions cause the processor to control additive manufacturing equipment to manufacture a coil structure according to the eighth aspect above.

[0042] According to the thirteenth aspect of this disclosure, a method for manufacturing a coil structure by additive manufacturing is provided, the method comprising: acquiring an electronic file representing the geometry of the coil structure according to the eighth aspect above; and controlling an additive manufacturing apparatus to manufacture the coil structure in one or more additive manufacturing steps according to the geometry specified in the electronic file. Attached Figure Description

[0043] Figure 1a A schematic diagram of a synchronous motor is shown;

[0044] Figure 1b The magnetic circuit connected to the coil is shown;

[0045] Figure 2a A schematic diagram of another asynchronous motor is shown;

[0046] Figure 2b The magnetic circuit with alternative coil positions is shown;

[0047] Figure 2c Showing Figure 2b Magnetic flux path in a magnetic circuit;

[0048] Figure 3 The magnetic circuit is shown, which is connected by a coil assembly with Litz wires;

[0049] Figure 4 An improved coil arrangement with different conductor profiles is shown;

[0050] Figure 5 A 3D view of the coil and magnetic circuit is displayed;

[0051] Figure 6A 3D view is shown of a twisted sub-conductor arranged in a slot of a multipole motor winding, wherein the outer conductor is solid;

[0052] Figure 7 A 3D view is shown of a twisted sub-conductor arranged in a slot of a multipole motor winding, wherein the outer conductor is also twisted.

[0053] Figure 8a The windings of an electric motor with inner conductors, outer conductors, and end winding conductors are shown.

[0054] Figure 8b The windings of an electric motor are shown, which has an inner conductor and an outer conductor, as well as end winding conductors including the top of the conductors.

[0055] Figure 9 Another winding of the electric motor is shown, including three connectors for applying voltage to the winding;

[0056] Figure 10a A mold for casting a portion of a coil winding is shown according to one embodiment;

[0057] Figure 10b The cross-section of the mold is shown; and

[0058] Figure 10c Another cross-section of the mold is shown. Detailed Implementation

[0059] Figure 1a A schematic diagram of a synchronous motor with a stator core 5 surrounding a rotor core 6 is shown. The stator comprises nine teeth with stator slots 16 between them. Coils 15 (shown for only one slot 16) are arranged around the iron core (extending from the inside to the outside of the slot 16) to induce magnetic flux in the cores 5, 6 to drive the motor. The arrangement of the coils 15 is referred to as a toroidal winding. The cross and dots shown on the coils 15 illustrate how, during use, current flows outward from the stator slot 16 along the page direction at specific times and returns inward along the page direction to the outside of the stator.

[0060] Figure 1b It shows Figure 1a A schematic cross-sectional view of a portion of an electric motor, where magnetic cores 5 and 6 are stator core 5 and rotor core 6, respectively. A single stator slot 16 with coil 15 is shown, where coil 15 has turns wound around stator core 5. An air gap 10 exists between magnetic cores 5 and 6, which allows the rotor to move relative to the stator.

[0061] Coil 15 has four turns around stator core 5, conductor portions 1, 2, 3, and 4 (as part of a continuous conductor) pass through the interior of the stator slot, and conductor portions 11, 12, 13, and 14 provide a return path for current outside the stator slot. That is, conductor portions 1 and 11 are part of the same turn of coil 15, while conductor portions 2 and 12 are part of another turn, and so on, because coil 15 runs around iron core 5.

[0062] Figure 2a A schematic diagram of a synchronous motor according to another embodiment is shown, wherein coils 15 are arranged around the stator teeth, from one slot 16 to another, rather than having a return path outside the stator. The same reference numerals are used for equivalent or similar features in different figures to aid understanding and are not intended to limit the embodiments shown.

[0063] Figure 2b It shows Figure 2a A schematic cross-sectional view of a portion of a synchronous motor, showing cores 5 and 6 with an air gap 10 between them. Four conductor portions 21, 22, 23, and 24 are positioned in conjunction with... Figure 1b The conductor portions 1, 2, 3, and 4 are in similar positions. The loop conductor portions 31, 32, 33, and 34 in this structure are located outside the magnetic core 5, close to the air gap 10.

[0064] Figure 2c A portion of the magnetic circuit is shown, for example Figure 2a and 2b The magnetic circuit of the electric motor. A magnetic field is generated in the air gap 10 as current flows through conductor sections 21 and 22 and returns through conductor sections 31 and 32. The magnetic field is visualized through equipotential lines (sometimes called flux lines). In the central section 7 of the air gap 10, these lines are parallel. At the edges of the air gap 10, the flux lines are further separated due to so-called edge flux. Edge magnetic fields 8 and 9 can pass through conductor sections 22 and 32 closest to the air gap 10.

[0065] If an alternating current is fed to the conductor portions 21, 22, 31, and 32 forming coil 15, an alternating magnetic field exists in the region surrounding the air gap 10 where the edge magnetic flux 8 passes through the conductor. This causes the electron path in conductor portion 32 to be pushed away from the air gap 10 and toward the upper surface of conductor portion 32. As a result, the current density distribution within conductor portion 32 is non-uniform. The portion of conductor portion 32 closer to the air gap 10 has a lower current density than the portion of conductor portion 32 farther from the air gap 10. A similar effect occurs in conductor portion 22 due to the presence of the edge magnetic field 9.

[0066] As the frequency of the alternating current increases, this distortion effect intensifies, and the utilization rate of the copper area in conductor sections 22 and 32 decreases. Conductor resistance increases, and conductor losses also increase. Similar effects occur in other conductor sections, such as 21 and 31, but the increase in losses is less significant because the magnetic flux is less dense at the edges of these sections far from the air gap.

[0067] Litz wire is typically used to reduce the aforementioned adverse effects, such as losses associated with high-frequency alternating current. Litz wire consists of multiple twisted strands, such as... Figure 3 As shown, each conductor section 41, 42, 43, 44 and 51, 52, 53, 54 represents four twisted wires. In practice, the number of strands in a Litz conductor is on the order of 101 to 102.

[0068] As the Litz wire extends further through the magnetic circuit, the multistrands are twisted, thus altering their position throughout the conductor. The Litz wire provides a more uniform distribution of current-carrying electrons across the entire cross-section of the conductor. This increased distribution reduces alternating current losses. However, the use of mutually insulated multistrands, and the requirement for twisting, reduces the amount of copper in the conductor's cross-sectional area; therefore, a twisted conductor may have a higher resistance to non-alternating current (DC) or lower frequency currents (e.g., <100Hz) than a solid conductor. Furthermore, there are conductors with lower edge flux in other parts of the magnetic circuit, and using Litz wire in these conductors leads to increased losses.

[0069] For example, in Figure 1b In this circuit, the return portion of conductor portion 2 is conductor portion 12. While conductor portion 2 will suffer from increased edge flux induced resistance, the edge flux of conductor portion 12 will be significantly reduced. Therefore, it is difficult to optimize the selection of individual conductor profiles to simultaneously accommodate conductor portions inside and outside the magnetic circuit.

[0070] Not all parts of an electrical winding require Litz wire, and in certain regions where AC effects due to the skin effect and proximity effect are less pronounced, winding performance degrades. In other parts of the winding, Litz wire provides performance improvements. The embodiments described herein provide coil structures with conductors that change from a single sub-conductor to multiple sub-conductors (such as Litz wire). Alternatively, the coil structure may include a section with more sub-conductors and another section with fewer sub-conductors. This solution can provide significant performance advantages to coil structures not available with conventional coil windings.

[0071] Throughout the coil structure, losses may not be uniformly distributed across a single turn; even at high frequencies, only certain portions of the turn will experience the highest AC losses. The coil structure disclosed herein features characteristics that allow it to utilize the material in the conductor as much as possible, with more sub-conductors in the areas of highest AC loss and fewer sub-conductors (or a single sub-conductor) in the areas where DC loss dominates.

[0072] The embodiments may be particularly useful for high-speed electric motors, such as those operating at speeds above 100,000 or 200,000 rpm and / or with AC frequencies greater than 1 kHz. For example, the embodiments can be advantageously used in turbochargers.

[0073] Figure 4 A magnetic circuit including coil 15 is shown according to one embodiment. The conductor portion 62 and the return conductor portion 72, located near the air gap 10 and the associated edge field, are divided into smaller conductors (i.e., each conductor portion includes multiple sub-conductors). However, the conductor portions 61 and 71, located away from the air gap 10, use solid conductors, which does not reduce the effective area available for copper. Therefore, the cross-sectional profile of the conductors can be selected to optimize the use of available area and minimize the effects of alternating current and edge magnetic flux.

[0074] It can be seen that conductor section 62 has a finite number of sub-conductors 621, 622, 623, and 624. Contrary to known design principles for Litz wire, the number of sub-conductors can be much smaller than that used in Litz wire. Surprisingly, it has been found that good performance can be obtained with fewer than 10 sub-conductors forming the cross-sectional profile of the conductor.

[0075] Furthermore, in the electromagnetic assembly according to this disclosure, a portion of the conductor can be present in the current path, thereby merging sub-conductors into a single conductor or a varying number of sub-conductors. This variation in the conductor profile can occur to optimize the use of the conductor region within the profile, minimizing DC resistance throughout the conductor path and minimizing the effects of AC resistance variations due to the skin effect or proximity effect, depending specifically on the location of the conductor portion within the magnetic assembly. This allows for optimal use of copper and minimizes copper losses throughout the electrical winding.

[0076] The cross-sectional profile of the conductor can be altered to maximize the use of material within the conductor. Depending on the position of the conductor portion relative to the magnetic circuit, it can be a single conductor with a solid or hollow profile, or it can include multiple sub-conductors.

[0077] Figure 5 A three-dimensional view of a portion of the coil structure according to this disclosure is shown. For example, it could be... Figure 4This is part of the coil structure. The coil structure has a height h. That is, the front portion of the conductor 62, which passes through the stator slot near the air gap, has a height h. The front portion of the conductor 62 includes four parallel sub-conductors. Preferably, the sub-conductors are twisted about a vertical axis (along the longitudinal direction of this portion of the conductor). The advantage of the sub-conductors being twisted within the cross-sectional profile of the conductor 62 can be seen. This advantage is maximized if the rotation of the conductor position about the axis (parallel to the current direction) results in an integer rotation at the magnetic circuit height h. This ensures that each sub-conductor has a balanced effect in the edge field near or away from the air gap.

[0078] In a further embodiment, an integer number of rotations of the sub-conductors about an axis parallel to the direction of current flow can occur over a length of N*h, where N is the number of slots through which the same conductor passes. In this way, an integer number of rotations of the sub-conductors ensures that each sub-conductor carries an equal amount of rim flux. The result should be that the resistance of each individual sub-conductor is approximately equal over the length of the conductor. In practical electromagnetic windings, it may not be possible to precisely achieve an integer number of turns of the sub-conductors. Even a non-integer number can still provide an improved current density distribution and lower resistance compared to a solid conductor.

[0079] Since twisting of the sub-conductor tends to reduce the percentage of area available for conduction, it has been found that when the conductor passes through the height (h) of N slots, the integer number of twists can be as low as 1, or 1 in each of the N slots.

[0080] exist Figure 1b In the middle, return conductors 11, 12, 13, and 14 are far from the air gap. They are not affected by the edge magnetic flux. Therefore, dividing these conductors 11, 12, 13, and 14 into sub-conductors offers little or no advantage. Thus, in one embodiment, the conductor is divided into sub-conductors and the sub-conductors are intertwined only in the portion where the resistance of the electromagnetic device would increase due to the edge magnetic flux passing through the conductor (i.e., the position of rotating the sub-conductors around an axis parallel to the direction of current flow only occurs in the portion of the electromagnetic device where the resistance would otherwise increase due to the edge magnetic flux passing through the conductor). For example, in Figure 1b In this embodiment, only the conductor portions 2 and 4 closest to the air gap can benefit from including sub-conductors and being twisted. In contrast, for conductor portions 1, 3, 11, 12, 13 and 14, the relatively large volume of the conductive material may lead to the use of a solid structure due to the lower resistance of the solid structure.

[0081] Figure 6 An example of a portion of a coil structure 100 for an electric motor according to an embodiment is shown. Below... Figure 8a and 8bThis illustrates how this section is integrated into the overall coil structure 100. The coil structure 100 can be used to provide... Figure 1a and 1b The coil 15 is shown. The coil structure 100 includes a conductor 101 providing a coil with five turns (in one stator slot). The front portion 102 (also referred to as “inner”) of each turn of the conductor 101, which forms the first part, is located in the slot of the motor near the air gap between the stator and rotor, and consists of four twisted sub-conductors 103 connected in parallel. Each twisted sub-conductor 103 is insulated from the other sub-conductors 103, for example, by a varnish coating. The rear portion 104 (also referred to as “outer”) of each turn of the conductor 101, which includes the return path, forms the second part at a (relative) long distance from the air gap of the motor, and includes (only) a single sub-conductor 105 (i.e., a single solid conductor portion). The top of the conductor 101, which closes the turn and connects the front portion 102 to the rear portion 104, is not shown in the figure. Due to the distance between the air gap and the associated edge field, having a single sub-conductor 105 may only result in a slight increase in resistance with increasing frequency. The bottom 106 of conductor 101 also includes a single sub-conductor 107 (i.e., a single solid conductor portion). Conductor 101 is U-shaped with gaps / spaces 108 for positioning a stator core (e.g., a laminated soft iron core) within the coil structure 100. The top of conductor 101 (not shown) can then be secured to the front 102 and rear 104 to close the structure 100, allowing conductor 101 to be "wound" around the core and arranged to provide magnetic flux within the core.

[0082] Figure 7 Another embodiment of the coil structure 100 is shown, which can form a coil in an electric motor. The coil structure 100 is similar to... Figure 6 The embodiment shown differs in that both the inner conductor portion 102 and the outer conductor portion 104 are composed of multiple twisted sub-conductors 103. Within each portion of the conductor, the shape of the outer contour of the conductor is different to optimize the use of the available area within the motor shape. This embodiment may be particularly useful when significant AC effects (e.g., due to edge fields) are present at both the front side 102 and the back side 104 of the conductor 101.

[0083] Figure 8a and 8b A further embodiment of the coil structure 100 is shown. Structure 100 typically includes a three-phase winding formed by connecting conductors 101 for connection to a three-phase input. The motor structure 100 may be formed in a ring shape, with the inner portion 102 of the conductors 101 close to the air gap. The outer portion 104 of the conductors 101 on the stator outer side forms the return path of the conductors 101. The coil structure 100 includes twelve conductors, providing twelve coils (one per stator slot) coupled together to provide a three-phase winding.

[0084] exist Figure 8a and Figure 8b In the stator, portions 109 and 106 of conductor 101 located at the top and bottom, also known as end windings, are made of solid conductor 107 (i.e., a single sub-conductor). Figure 8b A coil structure 100 is shown, which includes a top winding (i.e., the top 109 of conductor 101) added and connected to a corresponding conductor 101 at the bottom. The motor according to this embodiment can be made very compact. In this embodiment, portions 106 and 109 of the top and bottom conductors 101 can be solid, and a portion 102 of the conductor 101 extending through the length of the motor incorporates a twisted sub-conductor arrangement.

[0085] also, Figure 8b An assembly method is shown in which, after the stator core is inserted into the lower and vertical conductors, the top conductor is joined or welded to the other conductors.

[0086] Figure 9 An electric motor coil structure 100 is shown with three connectors 110, 111 and 112 connected to the top 109 of conductor 101 for providing three-phase input to the electric motor.

[0087] The design process for the coil structure can offer significant manufacturing advantages. In one embodiment, the coil is manufactured as a solid U-shaped structure, whereby the conductor is formed and insulated, enabling designs previously impossible using conventional invasive copper wire winding techniques. The U-shaped structure is then fitted to the top (or “end winding”) of the conductor using, for example, solder or welding. Furthermore, by using additive manufacturing (e.g., 3D printing), a stator can be added midway through the printing process, allowing the coil structure to be printed entirely around the stator. After the coils are formed, they are insulated, for example, by applying a varnish to the conductor.

[0088] These U-shaped conductors can be manufactured using additive manufacturing, or the molds can be 3D printed and cast with unique designs. Conductors made in this way allow for complete design optimization in simulation, and the exact number of conductors can be selected to balance the cross-sectional area of ​​the conductors at each point within a loop and to ensure uniformity throughout the machine or magnetic component. Furthermore, the mold itself can serve as insulation between the sub-conductors, thus remaining in place after casting.

[0089] Figures 10a to 10c A mold 114 is shown, which can be used to cast a portion of a coil structure according to an embodiment. Figure 10aThe mold 114 is shown, which can be used to cast the lower (U-shaped) conductor for the coil structure of a toroidal stator. The hollow 115 (negative space) in the mold is filled with a suitable material (typically molten copper) to form the conductor. Figure 10b A mold 114 is shown, which has a partially cut-off section to expose a conduit 116 for forming the bottom of a conductor, including a solid conductor. Figure 10c Mold 114 is also shown, but with a different cross-section to expose conduits 117 for forming the twisted sub-conductors at the front of the conductor. Mold 114 can be 3D printed and can comprise ceramic or other electrically insulating and thermally conductive materials. A similar mold can be used to cast the top of the coil structure. The stator core can be inserted into the mold before casting the coil structure around it.

[0090] The described manufacturing method allows for the production of very compact coil structures, where the length of the copper turns is as short as possible to connect the magnetic circuit. Furthermore, the optimal use of the copper region is to provide the lowest possible resistance across the entire operating frequency range of the machine, providing a method for manufacturing motors and transformers that are efficient over a wide frequency range.

[0091] Embodiments of the coil structure can be advantageously formed using additive manufacturing of the conductor portion of the coil structure, and simultaneously with insulation between the individual conductors and sub-conductors of the coil structure. An insulating layer then provides "fill" between the various portions of a conductive material (e.g., copper), while bonding the coil structure together without the need for additional supports. This is made from the conductive material itself in a single-material process and must later be cut away in a post-processing step. For example, a dual-material 3D printing process can be used. The two materials can be built simultaneously or one material at a time, but alternating between each material as the build height increases.

[0092] The manufacturing process can revolve around steel laminations. For example, a hollow shell can be printed with an insulating material first, and then the construction of copper windings (i.e., conductors with a coil structure) with continuous insulating sections can begin. An insulating layer is applied to any exposed conductors, and the steel lamination core can be inserted, after which printing can continue. The end result is a stator already completed within its shell.

[0093] Figure 6 Section 10 describes the structure of a motor with a toroidal winding scheme. This method can also be used for motor windings with the coil side placed in adjacent slots between the stator teeth. In this case, there will be some conductors on both sides of the coil close to the air gap, which will benefit from the sub-conductors. The end coils of the machine have less AC effect and can be solid conductors with a flat profile to minimize the additional length of the stator.

[0094] The examples according to this disclosure preferably use additive manufacturing processes. A common example of additive manufacturing is 3D printing. However, other additive manufacturing methods can also be used. Rapid prototyping or rapid manufacturing are also terms that can be used to describe additive manufacturing processes.

[0095] As used herein, “additive manufacturing” generally refers to a manufacturing process in which consecutive layers of material are provided on top of each other to “build” or “additively manufacture” a three-dimensional part layer by layer. This contrasts with some subtractive manufacturing methods, such as milling or drilling, in which material is continuously removed to create a part. Consecutive layers are often fused together to form a monolithic assembly that can have multiple integral sub-assemblies. In particular, the manufacturing process can allow examples of coil windings to be integrally formed and include various features that would be impossible to achieve using existing manufacturing methods. Especially, for a given volume of conductive material, a coil structure formed by additive manufacturing may occupy less space than a winding formed by conventionally winding copper wire. Additive manufacturing can also provide sharper (essentially 90°) angles for the turns of a coil winding.

[0096] The additive manufacturing methods described herein can produce any suitable size and shape with a wide range of features, which might be impossible using existing manufacturing methods. Additive manufacturing can create complex geometries without the use of any tools, molds, or fixtures, and with little or no waste. The only material used in additive manufacturing is the material required to form the part, rather than machining parts from solid plastic or metal blanks, the latter of which are mostly cut off and discarded. In particular, this allows for the formation of conductors that include both sections with multiple twisted sub-conductors and sections with a single solid conductor.

[0097] Suitable additive manufacturing techniques according to this disclosure include, for example, fused deposition modeling (FDM), selective laser sintering (SLS), direct selective laser sintering (DSLS), electron beam sintering (EBS), electron beam melting (EBM), electron beam additive manufacturing (EBAM), laser clean-shape manufacturing (LNSM), direct metal deposition (DMD), direct selective laser melting (DSLM), selective laser melting (SLM), direct metal laser melting (DMLM), direct metal laser sintering (DMLS), material jetting (MJ), drop-on-demand (DOD), laminated object manufacturing (LOM), and other known processes. The additive manufacturing processes described herein can be used to form parts using any suitable material (typically copper).

[0098] A single component made of multiple materials. For example, a component may include multiple layers, segments, or parts formed using different materials, processes, and / or on different additive manufacturing machines. In this way, components with different materials and material properties can be constructed to meet the needs of any specific application. Furthermore, additive manufacturing can be combined with other manufacturing technologies to provide a final product. For example, when forming a coil structure, a laminated core can be formed using conventional methods, and then the laminated core can be inserted into the coil structure after or during the additive manufacturing process.

[0099] Additive manufacturing processes typically manufacture components based on three-dimensional (3D) information about the components (e.g., a three-dimensional computer model (or design file)). Therefore, the examples described herein include not only the products or components described herein, but also methods for manufacturing such products or components by additive manufacturing, and computer software, firmware, or hardware for controlling the manufacturing of such products by additive manufacturing.

[0100] The structure of one or more parts of a product can be digitally represented in the form of design documents. Design documents, or computer-aided design (CAD) files, are configuration files that encode the configuration of one or more surfaces or volumes of a product's shape. In other words, design documents represent the geometric arrangement or shape of the product.

[0101] Design files can be in any file format now known or developed in the future. For example, a design file might be in stereolithography or Standard Tessellation Language (.stl) format created for a stereolithography CAD program for 3D Systems, or in the American Society of Mechanical Engineers (ASME) Additive Manufacturing File (.amf) format. The ASME standard is a format based on Extensible Markup Language (XML) designed to allow any CAD software to describe the shape and composition of any 3D object to be manufactured on any additive manufacturing printer.

[0102] More examples of design file formats include AutoCAD (.dwg) files, Blender (.blend) files, Parasolid (.x_t) files, 3D Manufacturing Format (.3mf) files, Autodesk (3ds) files, Collada (.dae) files, and Wavefront (.obj) files, although many other file formats also exist.

[0103] Design documents can be generated using modeling software (e.g., CAD modeling) and / or by scanning the product surface to measure the surface configuration of the product.

[0104] Once acquired, the design file can be converted into a set of computer-executable instructions, which, once executed by a processor, enable the processor to control the additive manufacturing equipment to produce the product according to the geometric arrangement specified in the design file. This conversion can transform the design file into slices or layers that will be sequentially formed by the additive manufacturing equipment. The instructions (also known as geometric codes or "G-codes") can be calibrated for a specific additive manufacturing equipment and can specify the precise location and quantity of material to be formed at each stage of the manufacturing process. As described above, this can be achieved through deposition, sintering, or any other suitable form of additive manufacturing method.

[0105] If needed, codes or instructions can be converted between different formats, converted into a set of data signals and sent, received as a set of data signals and converted back into codes, stored, etc. Instructions can be input to the additive manufacturing system and can come from part designers, intellectual property (IP) providers, design firms, operators or owners of the additive manufacturing system, or from other sources. The additive manufacturing system can execute instructions to manufacture products using any of the techniques or methods disclosed herein.

[0106] Design documents or computer-executable instructions can be stored in (temporary or non-temporary) computer-readable storage media (e.g., memory, storage system, etc.) that store code or computer-readable instructions representing the product to be produced. As noted, when the code or instructions are executed in the additive manufacturing system, the code or computer-readable instructions define the product that can be used to physically generate the object. For example, the instructions may include a precisely defined 3D model of the product and can be generated from any of a variety of well-known computer-aided design (CAD) software systems, such as... DesignCAD, 3D Max, etc. Alternatively, you can scan the model or prototype of the component to determine its 3D information.

[0107] Therefore, by controlling additive manufacturing equipment according to computer-executable instructions, the equipment can be instructed to print one or more parts of a product. These can be printed in assembled or unassembled form. For example, different parts of the product can be printed individually (as a set of unassembled parts) and then assembled. This may be particularly suitable for embodiments with coil structures. The U-shaped lower part and flat top of the conductor can then be formed separately and then fixed together. Alternatively, different parts can be printed in assembled form.

[0108] In view of the above, embodiments include a manufacturing method using additive manufacturing. This includes the steps of acquiring design documents representing a product and instructing additive manufacturing equipment to manufacture the product in an assembled or non-assembled form according to the design documents. The additive manufacturing equipment may include a processor configured to automatically convert the design documents into computer-executable instructions for controlling the manufacturing of the product. In these embodiments, once input into the additive manufacturing equipment, the design documents themselves can automatically lead to the production of the product. Therefore, in this embodiment, the design documents themselves can be considered as computer-executable instructions that cause the additive manufacturing equipment to manufacture the product.

[0109] In view of the foregoing, the design and manufacture of implementations of the subject matter and operations described herein can be implemented using digital electronic circuits or computer software, firmware, or hardware, including the structures disclosed herein and their structural equivalents, or combinations thereof. For example, hardware may include processors, microprocessors, electronic circuits, electronic components, integrated circuits, etc. Implementations of the subject matter described herein can be implemented using one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by a data processing device or for controlling its operation. Alternatively, the program instructions may be encoded on artificially generated propagating signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information for transmission to a suitable receiver device for execution by the data processing device. The computer storage medium may be or is contained in a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination thereof. Furthermore, although the computer storage medium is not a propagating signal, it may be a source or destination of computer program instructions encoded in artificially generated propagating signals. The computer storage medium may also be or be contained in one or more separate physical groups.

[0110] Although additive manufacturing technology is described herein as capable of fabricating complex objects by building them point-by-point, layer-by-layer, typically in the vertical direction, other manufacturing methods are possible and within the scope of this subject. For example, while the discussion herein involves adding material to form continuous layers, those skilled in the art will understand that the methods and structures disclosed herein can be practiced with any additive manufacturing technology or other manufacturing technique.

[0111] Although specific embodiments have been described above, those skilled in the art will understand that other embodiments may be provided within the scope of the claims.

Claims

1. An electric motor, comprising: The stator includes a first magnetic core and a coil structure, and a rotor configured to rotate about an axis, the rotor including a second magnetic core; An air gap exists between the first magnetic core and the second magnetic core; The coil structure said therein includes a conductor configured to provide a coil; The coil includes one or more coil turns surrounding the first magnetic core to induce magnetic flux in the first magnetic core during use, and the conductor includes: One or more first parts, which include multiple sub-conductors connected in parallel with each other; and One or more second portions coupled in series with the one or more first portions; wherein each of the one or more second portions includes a single sub-conductor, or a number of parallel sub-conductors less than the plurality of sub-conductors of the one or more first portions; and wherein at least one of the coils includes one of the first portions of the one or more first portions and one of the one or more second portions; the transition between the first portions and the second portions occurs at the two axially outer ends of the first magnetic core; and wherein each of the one or more coil turns is arranged around the first magnetic core of the stator such that each of the one or more first portions of the conductor is located in a stator slot of the stator and is closer to the air gap than at least one of the one or more second portions of the conductor.

2. The electric motor according to claim 1, wherein, The plurality of sub-conductors in each of the one or more first portions include a plurality of sub-conductors ranging from 2 to 10.

3. The electric motor according to claim 1 or 2, wherein, The sub-conductors of each of the one or more first portions are intertwined with each other.

4. The electric motor according to claim 3, wherein, The plurality of sub-conductors of each of the one or more first portions are twisted to provide one or more complete rotations of each sub-conductor.

5. The electric motor according to claim 1, wherein, The conductor is configured to couple the first part and the second part through a single sub-conductor.

6. The electric motor according to claim 1, wherein, The coil structure includes a plurality of conductors to provide a plurality of corresponding coils.

7. The electric motor according to claim 1, wherein, With respect to the coil, the conductor is arranged such that each of one or more first portions of the conductor experiences a stronger magnetic field than each of one or more second portions during use of the motor.

8. The electric motor according to claim 6, wherein, The plurality of coils are configured to provide a plurality of phase windings.

9. The electric motor according to claim 8, wherein, For each of one or more coil turns, the first portion is located in a stator slot of the stator adjacent to the air gap, and the second portion provides a return path outside the stator slot.

10. A method of forming a coil structure for an electric motor, the coil structure comprising one or more coils, the method comprising: The U-shaped portion is formed by additive manufacturing; Insert the magnetic core into the U-shaped portion; Form the top; and The top is secured to the U-shaped portion to provide a continuous conductor for each of the one or more coils, the continuous conductor providing one or more coil turns around the magnetic core; The coil structure is used for the stator of the electric motor; the electric motor includes a rotor configured to rotate about an axis; the coil structure includes a conductor configured to provide a coil, the coil including one or more coil turns around a magnetic core of the stator to induce magnetic flux in the magnetic core during use, the conductor comprising: One or more first parts, which include a plurality of sub-conductors connected in parallel with each other; and One or more second portions are coupled in series with the one or more first portions; each of the one or more second portions includes a single sub-conductor, or a number of parallel sub-conductors less than the plurality of sub-conductors of the one or more first portions; and at least one of the coils includes one of the one or more first portions and one of the one or more second portions; the transition between the first portion and the second portion occurs at the two axial outer ends of the magnetic core. Wherein, there is an air gap between the magnetic core of the stator and the magnetic core of the rotor; each of the one or more first portions of the conductor is located in the stator slot of the stator and is closer to the air gap than at least one of the one or more second portions of the conductor.

11. The method of claim 10, wherein the fixing step comprises bonding, welding, or soldering.

12. A method for forming a coil structure for an electric motor as described in any one of claims 1 to 9, comprising: Conductors are formed through additive manufacturing; and An insulating structure is formed between a portion of the conductor and its sub-conductors, wherein the insulating structure provides support for the conductor during the additive manufacturing process.

13. The method of claim 12, wherein the conductor and the insulating structure are formed by a dual-material 3D printing process.

14. The method of claim 12 or 13, further comprising inserting the magnetic core into the coil structure during the formation of the conductor.

15. A computer-readable storage medium having computer-executable instructions stored thereon, characterized in that, When executed by a processor, the computer-executable instructions cause the processor to control additive manufacturing equipment to manufacture the coil structure of the electric motor as described in any one of claims 1 to 9.

16. A method for manufacturing a coil structure by additive manufacturing, the method comprising: Obtain an electronic file representing the geometry of the coil structure of the electric motor as described in any one of claims 1 to 9; as well as Based on the geometry specified in the electronic file, the additive manufacturing equipment is controlled to manufacture the coil structure in one or more additive manufacturing steps.

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