Torque-intensive motor

Abstract

The present disclosure describes a magnetic transmission configured as an electric motor or generator. The device comprises at least a stator structure and a rotor structure arranged to improve torque generation. The stator structure includes N > = 1 stator cores and a common annular electrical winding, and the rotor structure includes an equal number of corresponding rotor cores. The instrument device may be a vernier machine. The apparatus may include one or more thermal channels configured to transfer heat from the stator structure. Methods and systems for manufacturing the device are also described.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 364,110, filed on May 3, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The technology typically involves electric motors and generators. Background Art

[0004] Electric motors are used in a wide range of applications, from powering fans and compressor pumps in heating, ventilation and air conditioning (HVAC) systems, driving the wheels of electric vehicles (EVs), to powering propellers in ships, electric aircraft or unmanned aerial vehicles (UAVs). Currently, there is an explosion of electrification, from electric vehicles to small and medium-sized electric drones to new electric passenger aircraft in the urban air mobility (UAM) market. There is a continuous explosion in the field of robotics and automated machines that require precise positioning. These new applications require lightweight and compact motors, especially to power mobile platforms where weight and size are critical.

[0005] Electric motors produce two things: torque (twisting force) and power. Power is defined as the product of torque and shaft speed. Power can be increased by increasing torque and / or speed. Traditionally, lightweight, high power density engines have been created by running at very high speeds (>10,000RPM), which is easier to manufacture lightweight, and then using a reduction gearbox to produce the shaft speed and torque required for the load. To put this in perspective, many modern electric vehicle engines run at 12,000-16,000RPM and then use a ~8:1 reduction gearbox to provide torque to the wheels. Other new engine types, such as direct drive ironless engines, are lighter weight for the required torque and power, but must use very large diameters if the speeds are lower. Loads such as propellers typically rotate at lower speeds to maximize aerodynamic efficiency, ranging from 150RPM for helicopters, ~1,000RPM for manned electric vertical take-off and landing (eVTOL) aircraft, and ~3,000RPM for fixed-wing aircraft. For robotic applications, the driven joints rarely rotate continuously but rather move from one controlled position to another, so peak joint speeds are typically well below 1,000 RPM and robots typically require very compact high-torque, low-speed motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A A stator of a motor topology (concentrated winding, outrunner type) is shown, which provides high power density but low torque density. Figure 1BThe stator of an engine topology (Vernier, inrunner) is shown, which provides high torque density, but is relatively heavy. Figure 1C A stator is shown for an engine topology (vernier, toroidally wound double air gap) according to an example embodiment of the present disclosure. Figure 1C The engine in the GT provides both high power and high torque density.

[0007] Figure 2 An engine architecture including a double air-gap vernier electromagnetic device with an end-turn sandwich structure, an immersed liquid-lubricated bearing, and integrated power electronics is schematically illustrated according to some embodiments of the present disclosure.

[0008] Figure 3A A dual air-gap radial flux machine configuration is shown in accordance with certain embodiments of the present disclosure.

[0009] Figure 3B A dual airgap axial flux machine configuration is shown according to some embodiments of the present disclosure.

[0010] Figure 4 A three air gap (2 radial, 1 axial) flux machine configuration is shown in accordance with certain embodiments of the present disclosure.

[0011] Figure 5A and Figure 5B An engine design employing a vernier electromagnetic device with a double air-gap radial flux configuration and Halbach array rotor magnetization is schematically illustrated according to some embodiments of the present disclosure. Figure 5A A machine with a pole ratio = 5:1 is shown, while Figure 5B A machine with a pole ratio = 11:1 is shown.

[0012] Figure 6 An open slot toroidal winding is shown in accordance with some embodiments of the present disclosure, detailing the use of wide flat ribbons made from multiple strands of parallel magnet wire.

[0013] Figure 7 A double air-gap vernier machine with a Halbach rotor magnet array configured as a radial flux machine according to some embodiments of the present invention is schematically illustrated.

[0014] Figure 8 A double air-gap vernier machine with a Halbach rotor magnet array configured as an axial flux machine according to some embodiments of the present invention is schematically illustrated.

[0015] Fig. 9A three-gap machine according to some embodiments of the invention is schematically shown, comprising two axial flux gaps and one outer radial flux gap. This embodiment employs heat pipes in the cooling channels to mechanically connect the stator core to the stator structure and for heat transfer.

[0016] Fig.10 A three-gap variant with two radial flux air gaps and one axial flux air gap according to some example embodiments of the present disclosure is schematically shown.

[0017] Fig.11 An axial flux double airgap machine with integrated power electronics and cooling features according to some embodiments of the present disclosure is schematically illustrated.

[0018] Fig. 12A and Fig. 12B A fully assembled double airgap axial flux machine is schematically shown, wherein the axial cooling airflow is driven by rotor housing integrated fan blades, according to some embodiments of the present disclosure.

[0019] Fig.13A -D schematically illustrates the assembly process of the end turn cooling sandwich structure of the stator according to some embodiments of the present disclosure.

[0020] Fig.14 A liquid cooling architecture of an axial flux design according to certain embodiments of the present disclosure is shown.

[0021] Fig.15 An example thermal FEA simulation of a radial flux vernier machine using heat pipes according to some embodiments of the present disclosure is shown.

[0022] Fig.16A and Fig. 16B 3D electromagnetic (EM) FEA simulations of eddy currents induced in different aluminum end turn sandwich construction methods according to some embodiments of the present disclosure are shown.

[0023] Fig.17A and Fig. 17B An example of a wound aluminum coil having an electrically insulating surface to block eddy currents according to some embodiments of the present disclosure is shown.

[0024] Fig.18A , Fig.18B and Fig.18C An example of an axial flux double air gap end turn sandwich structure utilizing a rectangular heat pipe according to some embodiments of the present disclosure is shown.

[0025] Fig.19A and Fig.19B A larger engine made by axially stacking engines according to some embodiments of the present disclosure is shown.

[0026] FIG. 20A to FIG. 20E Aspects of a dual air-gap radial flux embodiment are shown according to some embodiments of the present disclosure.

[0027] Fig.21A and Fig.21B A rotor is shown having an array of Halbach magnets implemented thereon, according to some embodiments of the present disclosure.

[0028] Fig. 22 A split-tooth vernier stator in the form of a radial flux outer rotor is shown in accordance with certain embodiments of the present disclosure.

[0029] Fig.23A and Fig. 23B A diagram of a five-air-gap axial flux engine is shown, according to certain embodiments of the present disclosure.

[0030] Fig.24A and Fig. 24B A diagram of a three-air-gap axial flux engine is shown, according to certain embodiments of the present disclosure.

[0031] Fig.25A and Fig.25B A diagram of a dual airgap axial flux engine is shown, according to some embodiments of the present disclosure.

[0032] Figures 26A-26F An embodiment is shown where the core and magnets extend continuously on the rotor.

[0033] Fig.27A and Fig.27B A vernier machine stator is shown that may be manufactured in angular segments according to some embodiments of the present disclosure.

[0034] Fig.28A and Fig.28B A compact winding method according to some embodiments of the present disclosure is shown, wherein the coil is formed from a wide band with specific cutouts in the end turn sandwich.

[0035] Fig.29 An automatic toroidal winding machine according to some embodiments of the present disclosure is shown.

[0036] Fig. 30A , Fig. 30B and Fig. 30C An axial flux machine of windings that may be formed using a printed circuit board (PCB) process according to some embodiments of the present disclosure is shown.

[0037] Fig.31A and Fig.31B A method of additive manufacturing of an axial flux engine according to some embodiments of the present invention is shown. DETAILED DESCRIPTION

[0038] The present disclosure relates to an engine technology that has significantly higher torque density and power density than the prior art known to the inventors. Using this technology, current high-performance engines can be replaced by engines that use only about half of the expensive permanent magnet materials and high-performance electrical steel. Therefore, this technology can save costs. In addition, using the disclosed technology with low-cost electrical steel and permanent magnets can still produce a relatively high-performance engine, but the material cost can be significantly reduced. For example, replacing high-performance neodymium iron boron (NdFeB) permanent magnets with much lower cost (and lower strength) ferrite magnets is a mechanism to produce a low-cost but still high-performance engine.

[0039] Most modern light-duty electric motors use concentrated windings, such as Figure 1A As shown. The coil span of concentrated winding is 1, resulting in the absolute minimum weight wasted in the end turns. However, this method is not torque intensive. Figure 1B An example of a conventional vernier motor is shown, which employs magnetic transmission to significantly increase torque density. The disadvantage is that a high magnetic transmission ratio (called pole ratio) requires a high coil span, thus having excessive winding weight wasted in the end turns. Figure 1B The example in shows an excess of 90 mm end turn copper in the winding relative to the 70 mm effective stack length that produces torque.

[0040] Therefore, the prior art provides engines that are light in weight but lack torque density (e.g. Figure 1A ), or an engine with high torque density but too heavy (e.g. Figure 1B ). As far as the inventors know, the prior art cannot provide an electric motor that is both sufficiently light and has a high torque density.

[0041] Figure 1C A stator 100 of a lightweight, high torque density electric motor using concentrated toroidal windings according to an embodiment of the present disclosure is shown. The electric motor comprising 100 employs magnetic gearing and comprises minimal end turns. In an exemplary embodiment of the present disclosure, two cursor motors are placed back-to-back in such a manner that, for example, Figure 1B Any ratio magnetic drive in the engine, the winding has Figure 1A This combination enables the construction of a motor that is both torque-dense and power-dense.

[0042] Faced with the need for an electric motor that is lightweight and has a high torque density, the inventor initially explored magnetic transmission (replacing mechanical gears) as a zero-wear reduction method. However, magnetic transmission requires an additional set of bearings, which themselves can fail, and also adds weight to the system. In the context of using magnetic transmission for electric motors, the inventor noticed that the full output torque of the magnetic gear is generated by the magnetic field, permanent magnets, and electrical steel components. The magnets and iron in the magnetic gear have weight but do not generate power (i.e., they are passive). Therefore, the inventor began to explore why the full output torque could not be generated directly with the engine, which led him to the technology of an exemplary embodiment that achieves this goal (i.e., directly generating the full output torque with the engine)!

[0043] Figure 2 An example of this technique is shown.

[0044] While exploring the literature on magnetic gears, the inventors stumbled upon a class of machines called magnetic gear machines (MGMs), which include vernier machines, which use magnetic transmission with their rotor magnets, pole / slot combinations, and open slot construction. Vernier engines are primarily used in very high torque, very low speed applications such as wind turbine generators. Since high-efficiency propellers typically rotate much slower than lightweight electric motors, vernier machines are good candidates for applications such as the direct drive aircraft propulsion applications the inventors were exploring. The challenge was to make them lightweight.

[0045] According to the present disclosure, in the process of building a lightweight, high torque dense engine, as a first step to achieve lighter weight at low mechanical speeds, a high pole count (i.e., a large number of poles, such as greater than 4) is used, which increases the electrical speed of the machine. Next, Halbach magnetization is used on the rotor to minimize the weight of the iron in the rotor core. High electrical speeds typically produce higher core losses, so very low loss electrical steel is used in the core of the example embodiment. In addition, the magnets are segmented to minimize eddy currents in the magnets.

[0046] Figure 1BA typical Vernier engine is shown, with a large coil span due to magnetic gearing, resulting in excessive copper in the end turns. One of the key insights into the technology that enabled the embodiments of the present disclosure was the realization that a Halbach "inner rotor" Vernier engine and an "outer rotor" Vernier engine could be arranged back to back to form a double air gap machine, with the stator being clocked so that short toroidal windings could be used. This approach virtually eliminates the excess winding of the end turns and produces a very compact machine. It was discovered that cooling channels could be passed through the center of the stator and rotor yokes without degrading the magnetic performance of the machine. All of this is combined with a thermally conductive cooling sandwich around the winding end turns (typically the hottest part of the engine) to produce very effective cooling. This mechanical / thermal design approach of the embodiments is referred to in the present disclosure as a "cold sandwich" construction.

[0047] Double air gaps have been used for coreless and conventional slotted engines (e.g., U.S. Pat. No. 6,924,574), and have been proposed in the paper "Quantitative Comparison of Novel Vernier Permanent Magnet Machines" by Niu et al., IEEE Transactions on Magnetism, Vol. 46, No. 6, pp. 2032-2035, 2010. However, these known techniques do not consider vernier machines as provided by embodiments of the present disclosure. In addition, some embodiments utilize a combination of Halbach magnetization with specific cooling methods. In addition, the techniques of the embodiments are equally applicable to radial flux and axial flux machines and combinations thereof. In addition, the techniques are equally applicable to embodiments of generators, linear motors, and actuators.

[0048] Potential applications of the engine of the example embodiment include, but are not limited to, those applications where weight and volume are important considerations. At the top of the list are electric aircraft propulsion engines for fixed-wing horizontal and vertical flight (such as helicopters and multi-rotor helicopters). Another type of application is an application that seeks to reduce or eliminate the reduction gearbox. The common motivation for doing so is to eliminate wear and maintenance items and reduce system volume and weight. Using the technology of the embodiment, mobile power generation from truck traction generators to even fixed standby generators can significantly save size and weight, making it easier to transport and install these devices. Similarly, due to the demand for larger electrical loads for all applications, generators on aircraft are increasingly required to generate more electricity. Air power generation attaches great importance to lightweight, compact and efficient generators. Evolving technologies such as robots have another reason to remove the gearbox, namely to realize back-drivable actuators that are more rugged and can achieve new control algorithms and robot performance. Motors that drive fans and pumps can benefit from more compact and lightweight motors, which are other potential applications.

[0049] Because the engine technology of the example embodiments of the present disclosure has significantly higher torque density and power density than the prior art, the technology can also replace current high-performance engines with engines that use significantly fewer expensive permanent magnets and high-performance electrical steel. Therefore, this technology can save costs. Likewise, this technology using lower-cost electrical steel and permanent magnets can still produce a relatively high-performance engine, but can significantly reduce material costs. For example, replacing high-performance neodymium iron boron (NdFcB) permanent magnets with lower-cost (and lower-strength) ferrite magnets is an option for manufacturing a low-cost but still high-performance engine.

[0050] Embodiments provide a new motor technology that produces very high torque at lower required speeds while still being efficient and very compact. In embodiments, this is achieved by combining multiple technologies in a unique way. In some embodiments, multiple technologies include vernier electromagnetics, high pole counts, Halbach array rotor magnets, two or more back-to-back engine stators with appropriate clocking, cooling channels sandwiched between two or more stator yokes, cooling fins integrated into the rotor structure, high thermal conductivity stator winding end caps, windings formed by bands composed of many smaller wire harnesses, integrated cooling fins on the engine housing, drive electronics integrated in the same engine housing, and cooling channels integrated into the rotor core. In some embodiments, one or more of the integrated cooling fins on the engine housing, the drive electronics integrated in the same engine housing, and the cooling channels integrated into the rotor core can be optionally included in the engine.

[0051] A vernier electromagnetic device is a type of magnetic gear machine (MGM). Vernier MGMs produce very high torque but typically have very large end turn sizes and masses (e.g. Figure 1B ). In example embodiments, the Vernier MGM is applicable to both radial and axial flux machines as well as linear motors, and it can also be used for induction, interior permanent magnet motors (IPM), synchronous reluctance motors (SRM), and synchronous motors (SM).

[0052] The high pole count technology incorporated into the engine of the present disclosure may have 4 or more permanent magnet poles. The high pole count can increase the electrical speed of the machine while keeping the mechanical speed low.

[0053] In some embodiments, a Halbach array rotor magnet may be used to maximize the flux density toward the stator and enable a thinner rotor yoke to carry the flux.Some embodiments may use a magnet arrangement other than a Halbach array.

[0054] Two back-to-back engine stators with timing as arranged in the example embodiment allow for very compact windings with minimal (e.g., absolute minimal) copper waste in the end turns, and places the rotor outside the machine, which enables the rotor to be cooled very efficiently to maintain low magnet temperatures.

[0055] The cooling channels sandwiched between the two stator yokes give the heat a very short path to escape from the stator through the cooling channels. The cooling channels can be filled with heat-conducting solids (called cooling strips), heat pipes, or liquid coolants. The cooling channels can be cavities within the stator and rotor laminations. The cooling channels can also be formed in the aluminum sheet - for example, by mounting / joining the two stator cores to a cooling plate. Effective cooling keeps the winding temperature low, which improves efficiency and extends the life of the winding.

[0056] In an exemplary embodiment, since the rotor structure is exposed to air, cooling fins integrated into the rotor structure can directly cool the rotor core and magnets. Since engine performance is limited by magnet temperature, this improves performance. Cooling fins integrated into the rotor structure also enable the use of higher strength magnets that require lower operating temperatures.

[0057] The high thermal conductivity stator winding end caps in embodiments are arranged to contact the winding end turns, thereby providing a low resistance path for heat to flow from the winding end turns to the cooling channels and the housing, and can be specifically constructed to not generate or minimize eddy currents that may reduce efficiency.

[0058] In some embodiments, ribbon windings composed of many smaller strands also contribute multiple properties. Fine stranding can reduce winding AC resistance and reduce eddy currents generated by the strands themselves in the open slots. Square / rectangular cross-section wires can be used to form the ribbon, which can achieve very high fill factors that improve efficiency.

[0059] In some embodiments, integrated cooling fins on the engine housing provide a very compact cooling solution.

[0060] In some embodiments, the drive electronics integrated into the same engine housing use the same cooling fins to achieve a very compact system. It can also make engine mounting and system design simpler because it does not require finding a location to mount the engine drive electronics.

[0061] In some embodiments, cooling channels can be integrated into the rotor core. Such channels help cool the rotor magnets and can form an integral centrifugal coolant pump. They can also provide a mounting function.

[0062] The above components, in various combinations, describe the features that enable the high torque dense motor provided by the embodiments of the present disclosure. Some of these features are unique to this engine technology and may require new manufacturing processes and systems to produce the engine. These manufacturing processes and systems include: a toroidal winding machine that can precisely control the wire entering the slot; an integrated cutting and winding method for manufacturing axial flux machines with internal and external cutouts; laminated aluminum end cap rings with winding cutouts; square / rectangular magnet wires are joined into strips and carefully folded to compactly arrange the wire strips; segmented stator assemblies; and modular stacking capabilities of axial flux engines to form larger engines.

[0063] Electromagnetic aspects of torque-intensive electric motors

[0064] Following are some electromagnetic aspects of the technology, selected combinations used in example embodiments to produce high performance, high torque density, and high power density motor / generators.

[0065] Figure 2 A dual air gap radial flux machine (e.g. Figure 1C ), and illustrates an example arrangement of the stator core 204, windings 206, rotor core 210, magnets 218, and cooling passages 214. Figure 2 Also shown are a shaft seal 224 and submerged bearing 226, integrated electronics 228, and heat sinks 220-222. These aspects will be further described below in conjunction with various embodiments.

[0066] Figure 3A and Figure 3B Two main configurations are shown in which engine technology according to embodiments can be constructed for radial flux machines ( Figure 3A ) or axial flux machine ( Figure 3B ). Figure 3A-3B Each shows a cross-sectional view of the upper half of an engine according to some embodiments, similar to Figure 2 The view shown in . Figure 3A The radial flux machine 300 in FIG. 3 includes a stator core 304 connected to a stator structure 302 , permanent magnets 318 , and a rotor core 310 connected to a rotor structure 308 such that a flux 320 is generated in a radial direction. Figure 3B The axial flux machine 330 in the embodiment includes a stator core 334 connected to a stator structure 332, permanent magnets 348 and a rotor core 340 connected to a rotor structure 338, so that a flux 350 is generated in the axial direction. The radial machine and the axial machine of the embodiment each include two air gaps. In the example embodiment, the air gap is the mechanical gap between the rotor permanent magnets and the stator core. Figure 3A and 3B The key components constituting the subject technology are shown separately. Key features include multiple air gaps ( Figure 3A316 and Figure 3B 346), winding (ring winding; Figure 3A 306 and Figure 3B 336 in), cooling channel embedded in stator core ( Figure 3A 314 and Figure 3B 344), and the end turn cooling characteristics ( Figure 3A 312 and Figure 3B 343 in ). In addition, the stator ( Figure 3A 304 and Figure 3B 344) and its cooling features connected to the stator structure ( Figure 3A 302 and Figure 3B 332 of ). The subject technology is characterized by a very short thermal path from the cooling features (end turn areas and channels) which transfer the heat generated in the windings and stator core to the stator structure and to the heat sink. While there are multiple ways to mechanically arrange the rotor and stator structure for each radial and axial flux variant, Figure 3A-3B Two examples are shown in FIG.

[0067] Figure 4 4. The invention shows how axial flux rotor cores and magnets can be added to a radial flux configuration to construct a three-gap machine 400 according to some embodiments. As shown, a stator structure 402, a stator core 404, windings 406, a rotor structure 408, a rotor core, permanent magnets, cooling channels 414, and end turn cooling features 412 are constructed in a manner similar to the radial flux machine 300. For the three-gap machine 400, additional stator core material (with a radial lamination direction) can also be added. With the addition of axial flow rotor cores and permanent magnets, the machine 400 includes three air gaps 416, three rotor cores 410, and three permanent magnets 418. The machine provides radial flux 420 as well as axial flux 422.

[0068] In a similar manner to machine 400, in another embodiment, a radial flux section may be added to an axial flux engine (either to the ID or OD) to form a different type of triple airgap machine.

[0069] In another embodiment, another axial flux rotor may be added (e.g., to Figure 4 The right side of the device shown) to form a four or five air gap machine. However, this additional axial flux rotor must be split in half to enable the stator to be connected to the stator structure. Fig.23A -B shows an example of a five-gap configuration. Configurations with increasing numbers of air gaps can be constructed in a similar manner. Let N be the number of air gaps, then N=3 is a three-gap engine, N=4 and N=5 are four-gap and five-gap engines, respectively. In the limit, it can be considered that N tends to infinity and the components of different air gaps merge into a continuum.

[0070] Figure 5A Certain electromagnetic aspects of an engine according to one embodiment are schematically shown, for example, a 60 pole, 36 slot engine with a magnetic transmission pole ratio of 5:1. A key aspect of this engine is that the system is actually composed of two engines 502 and 504 placed back to back. The circular boundary 506 demarcates the boundary between the two engines. There is an "outer rotor" type engine 502 on the outside of the circle 506 (so called because the rotor 510 is located on the outside of the stator 508). Then there is an "inner rotor" engine 504 in the circle 506, with the inner rotor 514 located on the inside of the inner stator 512. The arrangement of Halbach magnets 526 is shown in each engine. The example shown is a vernier machine, which is defined as an engine with magnetic transmission and a pole ratio >1.

[0071] The slot fill pattern indicates the phase of each winding, with shading 516 representing phase A, shading 518 representing phase B, and shading 520 representing phase C. For each phase, there are more densely patterned slots (e.g., slots 531, 534), marked with an "x", indicating where the winding entering the page must connect to another more sparsely patterned slot (e.g., slots 532, 533), which is marked with an "o", indicating where the winding must leave the page. The outer connecting semicircle (e.g., 530 shown in dashed lines) shows what a conventional winding would look like if the engine was equipped with a conventional winding. For the example shown, the pole ratio is 5 and the coil span is 3 slots. However, in the embodiment shown, the two stators 508 and 512 are oriented so that the entry and exit directions of the same phase of each winding are aligned, thereby allowing the option of winding it with a toroidal winding (and therefore with minimal excess end turns). As an example, two examples of toroidal windings 528 are shown. One of the annular windings 528 is shown extending from the inner stator slot 532 of phase B 518 to the outer stator slot 531 of the same phase, while the other of the annular windings 528 is shown extending from the outer stator slot 533 of phase C 520 to the inner stator slot 534 of the same phase. It is the radial timing of these two stators 508 and 512 that primarily enables very short end turn windings regardless of how large the coil span is. This, therefore, allows for the use of higher pole ratios (for higher magnetic transmission) without the corresponding increase in the weight of the winding end turns that would occur with conventional windings. An example of what such a conventional winding would look like if it were used is shown as dashed lines 530 between the slot pairs of each of the three phases. It should be understood that the example embodiment would not have a physical winding such as winding 530, but rather would have an annular winding 528 located between each pair of corresponding timed slots in the engine 500.

[0072] Figure 5BAnother example of a similar engine design 540 is shown, also with 36 slots, but Figure 5B The arrangement shown in has 66 poles, which results in a vernier machine pole ratio of 11:1. This higher pole ratio requires a larger coil span (6 slots), which results in a larger end turn mass if a conventional winding is used. The larger coil span 542 is shown in dashed lines in the example conventional winding. But in Figure 5B In the exemplary embodiment shown, the two stators (similar to engine 500) are timed so that they can be wound with short toroidal windings, thereby significantly saving weight associated with the windings. Figure 5A and 5B As can be seen, the length of the toroidal winding between the back-to-back stators is the same in both embodiments, although it would be significantly different if conventional windings were used. The same is true for engine 540, and as with engine 500, it should be understood that the exemplary embodiment does not have a physical winding such as winding 542, but rather has a toroidal winding (similar to 528) between each pair of corresponding timed slots in engine 540. Figure 5A and 5B The timing angle shown in shows the timing angle that results in the lowest winding mass. It should be understood that the timing angle between the two motors can be adjusted from this angle to address other design issues, such as ripple torque or power factor, but the winding mass will increase.

[0073] The open slot geometry used with the vernier machine enables the toroidal winding used in the example embodiment to have a very high fill factor (where fill factor is defined as the ratio of copper to the cross-sectional area of ​​the slot). High fill factors are desirable in the manufacture of high efficiency engines and light engines. The toroidal winding can use a solid (i.e., non-segmented) stator core, thereby reducing assembly costs and having superior magnetic properties to segmented cores.

[0074] Figure 6Detailed description of how toroidal windings of open slots (e.g., 602, 603) can achieve very high fill factors using flat strips of conductors (e.g., strips 604 and 606). This example shows how to form a strip from 6 square cross-section magnetic wires (e.g., 608). Each 608 copper wire can be wrapped by an insulation 610. Multiple strands of wire can be joined together to form a flat strip, which is, for example, 1 conductor width high and 6 conductor widths wide. The strip can be wound in a ring, showing how the winding starts from the bottom of the slot and then wraps around itself to form a 3-turn coil in this example. For example, strips 604 and 606 are shown as being wound in a ring 3 times between slots 602 in an outer stator 614 and slots 603 in an inner stator 612 (shown as formed between two teeth 618 in a stator yoke 616 of the inner stator 612). Two strips 604 and 606 are shown to illustrate that slots 602 can be filled by winding multiple strips and then connecting them in series or in parallel. Alternatively, a single strip may fill the slot width. Thus, embodiments are not limited to any particular number of strips. Although square cross-section magnet wires are shown, embodiments are not limited to such square cross-section wires and rectangular and circular cross-section wires may be used. Figure 6 The example in FIG. 6 shows an outer stator 614 and an inner stator 612 separated by a cooling channel / plate 620, which can be made of aluminum, for example, and carries the cooling channel inside it. In some embodiments, the two stators 612 and 614 can also be made of a single piece of electrical steel and form the cooling / mounting channel inside it. Arrow 622 indicates the direction of winding.

[0075] The open slot geometry used in many vernier machines enables Figure 6 The toroidal winding based on flat ribbons described in , resulting in a very high filling factor. The conductors in the open slots will be exposed to the fringing flux from the permanent magnets. If the conductors are too large, significant eddy currents will be induced, which will produce braking torques and reduce the efficiency of the machine. Therefore, it is beneficial to make many small strands into ribbons to limit the generated eddy currents.

[0076] Figure 7 Shown with Figure 5B and Figure 6 3D model representation of a radial flux engine corresponding to the illustrated embodiment. The figure also shows circular cooling channels in the rotor and stator yokes. For example, cooling channels (such as cooling channel 746) are provided in the stator 708, and cooling channels (such as cooling channel 744) can be formed on the outer rotor 710 and the inner rotor 714. These cooling channels can be used to perform thermal and mechanical functions. For example, they can transport heat away from the core and can also be used as a mechanical mounting feature. Figure 7Also shown is an annular winding 728 between correspondingly positioned open slots on the stator 708 (or inner and outer stators arranged back-to-back) of the radial flux engine.

[0077] Figure 8 Shows Figure 7 An axial flux variant of the engine embodiment shown. Figure 8 In the embodiment, the inner rotor 810 and the outer rotor 814 may not have cooling channels, while the stator 808 may be configured with multiple cooling channels 846. It can be observed that the orientation of the cooling channels 846 and the annular winding 828 is similar to Figure 7 The engine embodiments shown are different.

[0078] Figure 9-11 Several different ways in which a vernier electromagnetic device may be mechanically configured, as well as different cooling solutions, are shown according to some embodiments.

[0079] Fig. 9 It is shown how a double air gap axial flux machine can be combined with an external radial flux machine to form a triple air gap machine. The example shown uses heat pipes 904 embedded in the stator core 906 (windings are shown in the stator core) cooling strips (also called heat pipes) that serve a dual purpose, namely, transferring heat from the core to the stator structure 902 (shown as including cooling fins) and as a structural element for mechanically attaching the stator core 906 to the stator structure 902. The rotor housing 910 is made of a lightweight thermally conductive material, such as but not limited to aluminum, and has integrated cooling fins 912. In the embodiment shown, these fins are formed as centrifugal fans that drive cooling air through the rotor structure to cool the rotor core as well as the magnets. Additional fan blades that double as rotor spokes are also integrated into the rotor core. These blades form an axial fan that blows air through the stator structure to cool the stator. An integrated rotor structure and cooling fins (aluminum) 910 , three-sided magnets and rotor core 908 , stator core and windings 906 , cooling strips 904 , and stator structure and cooling fins (aluminum) 902 are shown.

[0080] Fig.10A similar approach is shown where a double airgap radial flux machine is formed into a triple airgap machine by adding a single axial flux component. The triple airgap engine includes three rotor cores 1016, 1018 and 1020, and three rotor magnet arrays 1017, 1019 and 1021, as shown. The lamination directions of the radial flux and axial flux machines are different to prevent eddy currents from occurring in various regions of the stator core. For example, the rotor cores 1016, 1018 and magnet arrays 1017, 1019 that are part of the radial flux machine have an axial lamination direction, while the rotor core 1020 and magnet array 1021 that are part of the axial flux machine have a radial lamination direction. The stator core 1024 is part of the radial flux machine, while the additional stator core 1025 is part of the axial flux machine. The stator core structure 1010 shown includes stator cores 1024, 1025, 1027 and an annular winding 1026 between the axial slots in the stator core. The stator cooling strip 1012 can be solid material, hollow coolant tube or heat pipe, integrated into the stator core. The rotor also has cooling fan blades 1028 integrated in the rotor housing 1004, but in this case, they are all axial fan blades. The stator housing / structure 1014 is used to mechanically mount the stator core 1010 (stator cores 1024 and 1025) and the winding 1026, and has a plurality of cooling fins 1030 integrated therein to facilitate the dissipation of the stator heat conducted to it by the cooling strip 1012 and the direct conductive path from the mounting feature. The bearing assembly 1002 and the magnet retaining band 1006 of the rotor housing 1004 are also shown. As shown, the winding 1026 is annular.

[0081] Fig.11An exploded view of a double air gap axial flux machine according to some embodiments is shown. The axial flux double air gap machine shown includes integrated power electronics and cooling capabilities. This shows a stator "cold sandwich" assembly 1108, which is an integrated component featuring cooling strips / channels and features in the end turn area that can effectively conduct heat away from the end turns and stator core and to the stator heat sink 1110. This example shows a corrugated stator fin heat sink that is highly integrated into the outer stator structure to cool the engine. The example features a portion 1102 that includes integrated drive electronics 1114 (e.g., power semiconductors, processors, and sensors) and its own corrugated heat sink (shown on the periphery of the structure) to dissipate the heat generated in the drive electronics. The technology example shows a rotor housing 1112 that wraps around the stator and has integrated axial fan blades 1116, much like the compressor blades of a turbine engine. As the engine rotates, these fan blades 1016 blow air across a heat sink (e.g., stator heat sink 1110). The stator core consists of stator electromagnetic components (including toroidal windings) 1106, a stator cold sandwich 1108 and a stator heat sink 1110. A stator frame (including bearing housing) 1104 is also shown. Figure 2 shows a cross-sectional detail of the design, Fig. 12A A more complete portion of the engine is shown.

[0082] Fig. 12A and Fig. 12B for Fig.11 Unexploded view of the motor shown. Fig. 12A The rotor housings 1204 and 1206 are shown. Fig.11 A rotor housing 1112 is provided in the figure which has incorporated axial flow fan blades 1116. Fig. 12B The end view in FIG. 1 more clearly shows how the technology integrates axial fan blades into the rotor housing to drive air through the corrugated fins 1208 (eg, Fig.11 1110 in FIG. Fig. 12A Also shown is an electronic heat sink 1202 (eg Fig.11 1102 in FIG. 1104 ).

[0083] The torque-intensive motor technology of the disclosed embodiments utilizes an end-turn sandwich structure assembled in Figures 13A-13D In this case, the stator consists of two stator core halves 1302, 1303 (see Fig.13A ), each half is made of high performance electrical steel and joined to a high thermal conductivity sandwich layer composed of 1304, 1306, 1308 and 1310. The sandwich layer contains cooling channels 1304 and is made of a high thermal conductivity material (such as aluminum) for the winding end turns in the corresponding slots 1306 and 1310. The stator prepared for winding is as follows Fig. 13B shown. Fig. 13B 13 shows two stator core halves 1302 and 1303, a sandwich layer piece 1308 after the two stator core halves have been joined. The stator is then wound with toroidal coils 1312 so that the toroidal coils 1312 are located in the slots 1306 between the end turns of the sandwich layer (eg, end turns 1310). Fig. 13C The wound stator is shown.Finally, the external coolant manifold 1316 and radiator 1314 are installed. Fig.13D A wound stator is shown with a heat sink 1314 and coolant manifolds 1316 and 1318 mounted. The windings generate the largest proportion of the engine's waste heat, and the structure provides a very short thermal path for the winding heat to reach the heat sink. It should be understood that FIG. 13 is a liquid cooled machine, but other embodiments utilizing cooling strips or heat pipes or plates are also contemplated.

[0084] Fig.14 shows the axial flux stator (e.g., in the corresponding Fig.13A -D axial flux machine) is divided into half and shows a cross-section of a variant with liquid coolant channels. The diagram 1400 shows the coolant flow 1412 in dashed lines, which meanders up in the coolant channel 1410 in one stator tooth 1420 and crosses the open slot 1406 to the next tooth 1421. The open slots (e.g., 1406, 1408) of the stator include annular windings. The thin arrows 1414 show how the heat generated due to core losses flows into the coolant 1412, as well as the heat generated in the windings (as shown by the thick arrows 1416 and 1418). Fig.14 It shows how short the path is from the heat source (e.g., core 1402 and windings in slots 1406, 1408) to the heat sink 1404. There are many ways to arrange electromagnetic devices (radial flux, axial flux), and many ways to arrange coolant channels and heat sinks for each type of machine. Fig.14 The coolant channel 1410 is shown flowing through the end turn sandwich region 1420, then flowing through the stator core 1402 to the other end turn sandwich 1421, and then flowing out to the housing 1422. Optionally, the coolant channel can meander only inside the stator core, such as Fig.25B As shown, it does not pass through the end turn sandwich region. Fig.14 Integrated heat sink fins 1404 are shown, but if liquid cooling is used, the coolant can pass to a separate discrete heat sink / heatsink. The channels can also contain only cooling strips without liquid cooling.

[0085] Fig.15A thermal finite element analysis (FEA) simulation of a simplified model of a radial flux double air gap machine according to an embodiment is shown, where a heat pipe 1508 is considered to transfer heat from the leftmost portion of the end turn sandwich region 1504 through the stator core 1510, then through the other side of the end turn sandwich region 1505 and out to the heat sink 1506. It is observed that the sandwich structure can significantly reduce the winding temperature after using an efficient heat sink. The gray scale from dark to light represents the temperature distribution from high temperature to low temperature. The heat sink 1506 is shown as a lighter shade, indicating a lower temperature, and the FEA shows that the temperature rise from the heat sink to the winding is small, so the winding remains cool.

[0086] A key challenge is choosing the best end turn core material. The core material needs to be highly thermally conductive, but it is in close proximity to the windings, which carry large, time-varying currents. Therefore, any conductive material close to or passing through the coils will induce eddy currents in them. Figures 16A-16B An analysis of two different sandwich construction formation methods based on electromagnetic FEA simulations is shown. Fig.16A The sandwich construction shown uses a solid aluminum piece with segments that pass through the coils. The area near and under the coils will produce significant eddy currents that can do more harm than good. Fig. 16B The sandwich construction shown illustrates the eddy currents generated in a segmented sandwich construction with insulation under the coils and solid aluminum to conduct heat to the cooling channels.

[0087] The preferred material for the end turn sandwich is aluminum nitride (AIN), a non-conductive ceramic with a thermal conductivity close to that of aluminum. Another alternative is to use laminated thin aluminum strips / sheets bonded together (see FIG. 17A to FIG. 17B ) and machined to form a sandwich. This is the same reason that electric motor cores are made of stacks of thin electrical steel sheets that are electrically insulated from each other. Anodizing aluminum is a way to create an electrically insulating surface, which can then be joined to other anodized aluminum sheets, or it can be wound around a mandrel to form a cylinder or ring. Fig. 17B The radial stack shown in FIG. 1 (e.g., 1706, 1708, 1710, with electrical insulation between each layer) illustrates an example Fig.17A The structure of a wound anodized aluminum winding coil 1702 is shown in FIG. The surface of the coil metal can be electrically insulated (e.g., a thin insulating strip 1704) to block eddy currents.

[0088] Figures 18A-18C An example of how an end-turn sandwich structure can be formed for an axial flux double airgap machine utilizing curved rectangular heat pipes to carry heat out of the core, windings and end turns to the stator housing and its integrated heat sink is shown. Fig.18A A cold sandwich stator 1802 and heat pipes (eg, 1804) are shown. Fig.18BStator 1802 is shown mounted in a stator housing 1806 that includes a heat sink 1808 . Fig.18C A rotor housing 1810 is shown having integrated centrifugal fan blades 1812 that drive cooling air radially to cool the rotor. Ducting may be used to turn the air and drive it axially through the stator cooling fins 1808.

[0089] Fig.19A and Fig.19B Shows how axial flux machines can be stacked axially to form a larger engine. Fig.19A Three engines 1904, 1906, and 1908 are shown stacked together to form a larger engine (stacked engine / machine) 1902. This example is shown in Fig.19B The cross-section of machine 1902 shown illustrates how rotor cooling blades (eg, 1912 ) pull air from the center of the machine to the inner sections of the engine to maintain uniform cooling of the stacked machine 1902 .

[0090] Figures 20A-20E Aspects of a dual air gap radial flux embodiment are shown, e.g. Figure 3A The embodiment shown in . Fig. 20A An example of an assembled engine is shown. Fig. 20B The stator is shown with one of the multiple coils making up the winding 2006 hidden to more clearly show the slots 2002. In the illustrated embodiment, the coolant passages 2004 may include metal tubes to mechanically connect the stator core 2008 to the outer frame / housing 2010. Fig. 20C Shows Fig. 20B The side view of the stator in Fig.20D The stator is shown in a front view and includes a rotor core and magnets. Fig.20E A rotor is shown with magnet arrays 2012 and 2014 attached.

[0091] Fig.21A A rotor is shown on which a Halbach magnet array is implemented. Fig.21B The Halbach array is more clearly shown. It should be noted that although the Halbach array shown is composed of 4 magnet segments, each of which has a 90 degree change in flux direction, it is not limited to this. For example, for other methods, a Halbach array of 8 magnets (e.g., 45 degree changes in direction between magnets) can be used. In some embodiments, it can be as follows Fig.21A The Halbach array implementation of the magnets in the rotor is shown in FIG. Fig.20E The standard magnet array (ie non-Halbach) in the rotor is shown.

[0092] Fig. 22 A split tooth vernier stator in the form of a radial flux outer rotor is shown in accordance with an embodiment. One of the plurality of coils 2206 is hidden to more clearly show the semi-enclosed slots 2204 formed between a pair of "shoe teeth" 2202. The split tooth vernier machine embodiment has semi-enclosed slots, while many of the embodiments shown in the other figures have open slot vernier machines. The semi-enclosed slots can be wound using conventional manufacturing methods, but are more difficult to wind with toroidal windings than open slots. The stator teeth and split tooth tubercles in the open slot structure act as flux regulators, which are essential for the magnetic transmission effect in the vernier machine.

[0093] Fig.23A and Fig. 23B A view of a five air gap axial flux engine is shown in accordance with some embodiments. Rotor core / magnet assemblies 2302 and 2304 represent two axial flux directions, rotor core / magnet set 2306 represents one radial flux direction, and smaller rotor / magnet assemblies 2308 and 2310 represent two additional radial flux directions, thereby providing a five air gap engine.

[0094] Fig.24A and Fig. 24B A view of a three air gap axial flux engine is shown in accordance with some embodiments. Rotor core / magnet assemblies 2402 and 2404 represent two axial flux directions, and rotor core / magnet assembly 2406 represents a radial flux direction, thereby providing a three air gap engine.

[0095] Fig.25A and Fig.25B A view of a dual air gap axial flux engine is shown according to some embodiments. Rotor core / magnet assemblies 2502 and 2504 represent two axial flux directions, thereby providing a dual air gap engine.

[0096] Figures 26A-26F An embodiment is shown where the core and magnets extend continuously on the rotor rather than in segments (e.g., rather than segments, such as 2402-2406). Mathematically, this can be expressed as a representation of the engine, i.e., as the number of air gaps N in the engine tends to infinity, the spacing between them tends to zero and becomes a continuum of air gaps. Fig.26A , the rotor magnets 2602 are visible and they hide the view of the stator. Fig.26D The rotor magnets are hidden, leaving the coils 2608 and stator core 2606 visible. Fig.26B , 26C , 26E and 26F show cross sections of the motor. It should be noted that if Fig.26C The representation in is stretched to form a cylinder, similar to a hydraulic cylinder, which represents a linear actuator / motor.

[0097] Building torque-dense electric motors

[0098] FIG. 27A to FIG. 31B Technical aspects related to a unique manufacturing method for making a multi-air-gap magnetic transmission machine are shown.

[0099] Fig.27A and Fig.27B Two stator slots with the same number of slots (e.g. Fig.15 Flux lines of an FEA simulation of a vernier motor with a different magnetic transmission ratio (pole ratio) (shown in FIG. 2 ). Overlapping triangles 2702 and 2704 show the smallest atomic segment. The motor is an integer multiple of this unique segment (i.e., the flux pattern repeats). Fig.27A An engine with a pole ratio of 5:1 formed by 12 repeating segments is shown. Fig.27B An engine with a gear ratio of 11:1 formed from 6 repeating segments is shown. When manufacturing the stator, multiple segments can be made, which can be any integer multiple of the atomic segment and then assembled into the final stator. Although it may not be economical to make 12 segments, both machines can be segmented in other ways, such as in halves or thirds. Open segments make winding of stator segments easier and reduce winding costs because the topology of the toroidal winding becomes simpler. However, the individual segments must then be assembled, which increases assembly costs and reduces magnetic performance.

[0100] Figures 28A-28B A method is shown for deterministically and compactly winding a multi-gap vernier machine when using flat, wide conductor strips (e.g., strips 2802, 2804) and having fine cuts (e.g., as shown in 2806, 2808) in the end turn sandwich (e.g., 2810, 2812). Fig.28A shows the folded tape winding exit (from the winding), while Fig.28B The folded tape winding entry (into the winding) is shown. Careful design of the folds and cavities maximizes the contact area of ​​the winding to the sandwich structure while minimizing the additional end turn volume.

[0101] Fig.29 An example of a toroidal winding machine 2900 capable of winding a multi-gap vernier machine of certain embodiments is shown. The challenge with this technology is that in order to form the toroidal winding, the winding wire / ribbon must be rolled up on a sub-spool that is small enough to pass through the interior of the core. For the most compact winding, all phases must be wound sequentially, first winding all adjacent slots for one phase, then switching to the next phase and winding all adjacent slots for that phase, switching again, until the first set of slots for all phases have been wound, and then the first phase passes over or around the slots just wound and the process repeats. Fig.28AThe winding is shown leaving one slot and the end turn 2806 crosses two slots occupied by other phases and then re-enters another slot. Fig.27A As shown on the left and Figure 5A The winding pattern matches the 36-slot, 60-pole, 5:1 pole ratio motor detailed in . Since the slot-to-slot conductors must cross over to other slots, the winding process must be done slot by slot, alternating phases to form the most compact and balanced winding, but other methods are possible. Fig.29 A three-phase winding is shown, so three sub-spools (sub-spool phase A 2902, sub-spool phase B 2904, and sub-spool phase C 2906) are used for winding. The method involves an actuating ring 2908 that grabs one sub-spool and rotates it to form a toroidal winding coil in the slot. The actuating ring can be opened to unlock the interlocking of the two toroidal coils. The actuator 2908 or another robotic arm (e.g., a positioner 2910) can then, for example, move the sub-spool to a parking position and then grab the next sub-spool. The positioner 2910 can be a general purpose robotic arm or a more specialized actuator made specifically for this winding operation. If the stator core is a segment rather than a complete toroidal core, the winding process can utilize the positioner alone to manage the spool changes and stop / start operations.

[0102] Fig.28A and Fig.28B The inter-slot winding shown shows the tape crossing the top of the slot. The inter-slot tape can be placed below the end turns of the winding. To accommodate this, the end turn length must be made larger, which may not be worthwhile for wide bands, but it is possible. This end turn extra length can be reduced slightly when multiple tapes are used. In addition, each phase can be wound separately if the inter-slot tape is located below the end turns of the subsequent slot. There are challenges in ensuring that the windings are exactly the same length and balanced because each phase has a different inter-slot pattern. However, this eliminates the need to park the sub-spools after each slot is completed.

[0103] An alternative to the toroidal winding method shown in Figure 30 is to use a printed circuit board (PCB) process to form the coils and end turns of the winding. Figure 6 The PCB process is somewhat limited in the packing factor achievable compared to the wideband process shown, but it is well suited to smaller engines where it is more difficult to make a sub-spool small enough (such as would be required if machine 2900 were used) to pass through the inner diameter of the stator core. Fig. 30A Shown is how the flat PCB stator windings 3002, 3003 would be integrated into a dual air gap axial flux vernier machine. Note that there are two winding PCBs per air gap. The PCB stator would work equally well for a single air gap axial flux machine, vernier or standard. Fig. 30B and 30C Coolant ports 3004 and 3006 are shown, along with corresponding coolant passages 3008. One challenge with vernier engines is that the electromagnetic drive requires open slots, so the windings require fine insulated strands to form the windings to minimize eddy current losses in the conductors. The etching limitations of the PCB process dictate how narrow the gaps between the conductors can be. As a result, the PCB winding process will have a lower packing factor and may be less efficient than a tape winding method, or heavier. However, for low speed applications, eddy current losses are not as important, so this issue is less severe.

[0104] Fig.31A and 31B A strip of thin core material (e.g., electrical steel) is shown being wound around a mandrel to form a toroidal core. The most basic version is to wind a simple flat strip to form a cylindrical core (a toroidal coil with a rectangular cross-section). The concentric layers of the core can be connected into a rigid core in a manner similar to conventional stacked laminations, either by adhesively joining the layers, using interlocking snap features, or by welding. If the core is strong enough, features can be machined into it. However, Fig.31A It is shown that external and internal features (e.g., 3102, 3104) can be cut into the tape (e.g., 3106) before or during winding and then wound onto the full-feature core. This is the winding equivalent of the common stacking method used in radial flux machines, where the slot features and cooling cavities are laser cut, etched, or stamped into the individual stacks before the stacks are assembled. The method shown can cut the features by laser cutting, stamping, or photolithographic etching. The spacing between the slot and cavity features must be carefully controlled and constantly varied throughout the process because these features tend to be further separated as the radius of the winding increases.

[0105] Fig.31B It shows how to use this process to form complete internal channels (e.g. Fig. 30C 3008 as shown), thereby forming a serpentine coolant path such as one that passes through the entire core but has only two small ports (e.g., Fig. 30B Ports 3004, 3006 are shown). Interlocking buckles can be punched in as precision timing features to maintain proper feature registration during the winding process. Buckles can also keep the stack in precise alignment until a later resin infusion step, for example. The manufacturing method can be used for any thin ribbon or sheet material, such as aluminum or carbon fiber. The method can be used to form aluminum end turn sandwiches for radial flux machines, with cutouts for end turns, for example.

[0106] In an exemplary embodiment, the problem of high efficiency electric motors being too large and heavy is solved by a multi-gap magnetic drive machine with compact toroidal windings that utilizes thermally conductive and structural spine / sandwich components to mechanically hold the stator and conduct away waste heat.

[0107] In the engine, p r =p FM ±p s , where: p r - Number of rotor pole pairs, p s - Number of stator pole pairs, p FM -The number of flux regulators. The pole ratio is defined as p r / p s Non-magnetic drive motors (most standard motors) have a pole ratio of 1, while magnetic drive motors have a pole ratio greater than 1.

[0108] In an embodiment, the multi-airgap magnetic transmission machine comprises a vernier motor.In the open slot configuration of the example embodiment, the number of flux modulators is the same as the number of stator slots / teeth.

[0109] The stator core of the engine in the embodiment can be formed of electrically insulating layers / laminates or particles. The use of thin electrical steel laminations can minimize stator core losses. For the laminations, the lamination direction is the product of the lateral air gap surface and the direction of motion (i.e., perpendicular to both). The stator has yokes (rings) and teeth made of ferrous materials (e.g., relative magnetic permeability much greater than 1). In some embodiments, a thermally conductive frame is fixed to the back of the stator to provide mechanical structure and conduct heat out of the stator.

[0110] The engine rotor in the example embodiment can be constructed of solid steel to save cost, or can be made of insulating laminations or particles. Thin electrical steel laminations can be used to minimize the rotor core. In some embodiments, the rotor can be a surface permanent magnet (SPM) rotor, which has magnets joined to a rotor ring structure (e.g., joined to a rotor yoke). The rotor has a yoke (ring) made of an iron-containing material. In some embodiments, the rotor can have magnets buried inside the core (e.g., internal permanent magnets (IPM)). The rotor magnets may be "skewed" to reduce torque fluctuations. The rotor magnets can be segmented tangentially and axially, with an electrical insulation layer between them to reduce eddy current losses. A thermally conductive frame is fixed to the back of the rotor, providing mechanical structure and conducting heat away from the rotor.

[0111] In some embodiments, the use of Halbach magnetization for the magnets in the rotor enables a multi-gap magnetic transmission machine to have very small size and very low weight. In an embodiment, for several rotor magnetization options, it was found that the use of surface permanent magnets arranged in a Halbach array can provide the highest torque with the lowest weight.

[0112] However, embodiments are not limited to using Halbach magnetization in the rotor. The magnetic transmission of embodiments can work with many other types of rotor magnetizations, including, for example, standard magnet arrays (e.g., alternating north magnets, south magnets), consecutive poles (e.g., small steel teeth around the magnets), and interior permanent magnets (IPM). Alternatively, in some embodiments, the rotor may have no magnets at all, according to a synchronous reluctance motor (SRM) design.

[0113] The windings consist of coils connected together, made from wound strands or "formed" rectangular copper bars. Concentrated windings have minimal "end turns" to reduce weight. Formed windings have the highest "fill factor", minimizing ohmic losses.

[0114] Embodiments use toroidal windings. The technology of the embodiments provides a stator core formed by a torus with teeth (and therefore slots). The winding wires are installed in the slots, rather than being evenly distributed around the torus as in a toroidal transformer. Wire harnesses or bands can be used to mitigate skin effect losses. The position of the wire harness can be controlled to mitigate proximity effect losses (e.g., Litz wire controls the position within the slots, bands, and band segments that twist between slots). In some embodiments, the windings can be segmented for redundancy. The windings can be segmented to provide different series / parallel combinations for induced voltage / impedance control. The windings and / or end turns can be formed from PCBs of axial flux machines and radial flux machines, respectively. In some embodiments, a combination of etched copper foil laminates can be stacked or wound to form a flat or circular winding or circuit.

[0115] Embodiments arrange the stator and rotor in a multi-airgap topology by placing multiple (e.g., 2-5) engine sections "back to back" (e.g., more than 50% of the stator cross-sectional circumference has flux across the air gap). The slots associated with each air gap can be rotated or moved relative to each other (i.e., timed to move) to trade off between magnetic efficiency and winding size. Timing can be used to offset or minimize the torque fluctuations generated in each air gap. A thermally conductive and structurally strong frame is located in the "center" of the core to mechanically support the core and carry away heat. The frame can be hollow and carry a cooling fluid. In some embodiments, the stator slots can be "skewed" to reduce torque fluctuations.

[0116] The term "skew" may be used to refer to the twisting of the axis of rotation of any feature in the stator core, rotor core, or magnets. Such twisting can be configured to control torque fluctuations.

[0117] The term "timing" can be used to refer to the relative angle between two components that share the same axis of rotation. This can also be called alignment or registration. While timing usually refers to continuous angular alignment, the term "indexing" can be used to indicate a discrete integer of angular options.

[0118] The magnetic materials (cores and magnets) of the embodiments can be constructed in a variety of ways. For example, they can be constructed from laminated sheets, using thin laminates or segments with electrically insulating layers between the laminates. In another example, they can be constructed from particles, using particles with electrically insulating films / layers between the particles. These particles can be sintered into a solid (e.g., ferrites), or can be bonded to an epoxy matrix (e.g., bonded magnets).

[0119] Eddy currents are another engine construction challenge. Engines are made of ferromagnetic cores, windings made of copper, and some engines also include permanent magnets, all of which are conductive. When conductive materials are exposed to time-varying magnetic fields, eddy currents are generated, which is a significant source of power loss or energy waste in the engine. To mitigate these loss sources, embodiments can be configured to prevent eddy currents from flowing in each component.

[0120] In some embodiments, as a general description, a method of mitigating eddy currents in a conductive component is to divide the component into several smaller components and place an electrically insulating layer between them.

[0121] For example, for ferromagnetic cores (e.g., stators and rotors), one method to mitigate eddy currents in embodiments is to use a stack of thin laminations of "electrical steel" where each lamination has a thin electrically insulating coating to prevent current from flowing in the lamination direction (from lamination to lamination). Electrical steel is an iron alloy with high magnetic permeability and high electrical resistance. Another method is sintered powder metal where the ferromagnetic particles have an electrically insulating film. This results in minimal losses and the amount of flux can flow in both the axial and radial directions.

[0122] The winding is formed by a set of coils connected in series and parallel as appropriate. The coils are composed of one or more "magnet wires", each of which has a thin resistive coating to limit the current to flow only along the length of the wire. The strands are also typically selected to mitigate the "skin effect" to achieve the lowest AC resistance (thus minimizing ohmic losses). Some embodiments further improve the winding resistance by using rectangular or square magnet wires and carefully controlling the placement of each strand. This maximizes the "fill factor", that is, the ratio of the cross-sectional area of ​​the copper to the cross-sectional area available in the coil "slot". In some embodiments, the strands can be twisted in a specific manner, commonly referred to as "Litz" wire (e.g., Litz wire in a 7 / 8 type structure or strip), to mitigate the so-called "proximity effect", in which different strands in the same bundle (or electrical node) have different induced voltages due to their relative positions in the slot. Litz twisting or other controlled holding placement methods can be used to ensure that each strand spends approximately the same length in all potential slot locations, thereby equalizing the voltage difference from strand to strand.

[0123] For permanent magnets (PM), in example embodiments, the PMs may be separated in the tangential and axial / stacking directions with electrical insulation (either insulating material or just spacing) between the magnet segments to mitigate eddy currents. This is called a "segmented magnet".

[0124] In the embodiments of the present disclosure, the problem of high efficiency motors being too large and too heavy is solved by using relatively small stator and rotor masses to maximize flux linkage. In the example embodiments, the task of transferring electromagnetic torque to a moving / rotating output is solved by using electromagnets to generate a moving (e.g., time-varying) magnetic field that interacts with the magnetic field generated by permanent magnets. The task of maximizing flux linkage and torque is solved by using magnetic transmission. A vernier is a type of magnetic transmission machine used in the example embodiments.

[0125] Vernier magnetic transmission requires a coil span greater than 1, a slotted structure of the stator to enable the time-varying flux to cross the permanent magnets, and a ferromagnetic (e.g., silicon, cobalt steel, or other) rotor core to carry the vernier flux. However, these aspects of the vernier also bring challenges: large coil spans result in large end turn masses using standard winding methods; slotted structures can produce side effects due to proximity effects (e.g., uneven voltage and current distribution across the slots); time-varying flux across the permanent magnets causes magnet eddy current losses; and the vernier flux carried by the rotor core causes rotor core losses.

[0126] In an embodiment, the challenge of large end turn winding mass is solved by placing two or more stators back to back and aligning them relative to each other and forming a toroidal coil (Gramme winding) to form a compact winding with minimal end turn copper. In some embodiments, the challenge of proximity effect losses is solved by making a strip of stranded wire and controlling the twist between stator slots and / or technologies such as Litz wire braids / strips. In some embodiments, the challenge of acting torque and removing heat from the stator is solved by placing structural and thermally conductive ridges between the stators and connecting to the frame. In some embodiments, the challenge of ohmic losses (e.g., heat) in the winding is solved by forming a strip with rectangular / square wire to minimize the winding resistance in the limited slot area. In some embodiments, the challenge of minimizing the rotor mass is solved by using a permanent magnet Halbach array, which produces more flux and reduces the rotor core thickness at the same mass. In some embodiments, the challenge of rotor heating is solved by conducting the heat generated in the magnets and core to the rotor frame, which conducts the heat away, and the frame can also transfer electromagnetic torque to the load output. In some embodiments, the problem of magnet eddy current loss is solved by dividing the magnets with thin electrically insulating barriers.

[0127] The implementation of this technology makes it possible to eliminate the transmission in many applications. Eliminating or reducing the transmission helps reduce weight and eliminates or reduces lubrication systems such as pumps, filters, pipes, etc.

[0128] The embodiments discussed so far have referred to the invention as an electric motor. However, the engine can also be used as a generator or alternator. When the rotor is rotated using mechanical shaft power, a voltage is generated in the windings which will provide power to the load. Therefore, the engine is equally well suited for generator applications as for engine applications.

[0129] In one aspect, the present disclosure provides a magnetic transmission device configured as a motor or a generator. The device includes a stator structure and a rotor structure for improving torque generation. The stator structure includes N or more stator cores and a common annular electrical winding, and the rotor structure includes an equal number of corresponding rotor cores.

[0130] A device as described in the previous paragraph, wherein the device is a Vernier machine. The N stator cores of the Vernier machine are arranged back-to-back. The N stator cores can be integrated into a single physical core.

[0131] An apparatus as described in any one or more of the above paragraphs, wherein a corresponding cold sheet (e.g., a "cold plate" (i.e., a planar cooling structure) for an axial flux machine or a "cold cylinder" for a radial flux machine) and one or more cooling channels are arranged between each pair of stator cores. Each cold plate may include one or more cooling channels.

[0132] The apparatus described in any one or more of the three paragraphs above may include any one or a combination of the following: one or more thermal channels configured to transfer heat away from the stator structure; a housing structure and a plurality of mechanical supports configured to connect N stator cores to the housing structure; a plurality of magnets arranged in a Halbach configuration and attached to at least one rotor core; N stator cores and / or N rotor cores configured to reduce eddy currents; electrically insulating ferromagnetic laminations whose lamination direction is orthogonal to the air gap surface and to the direction of movement of the rotor relative to the stator, thereby limiting eddy currents within the stator and rotor cores; the N rotor cores and / or the N stator cores are formed of ferromagnetic particles that are electrically insulated from each other, thereby limiting eddy currents within the rotor and / or stator cores; the N stator cores include stator core teeth arranged in a basic slotted configuration for flux modulation.

[0133] The device described in any one or more of the above four paragraphs may have N stator cores substantially fused within the stator structure and / or N rotor cores substantially fused within the rotor structure, so that the annular winding is substantially surrounded by the substantially fused stator and / or the substantially fused rotor.

[0134] The apparatus described in any one or more of the five preceding paragraphs includes a housing structure and a plurality of mechanical supports configured to connect the N stator cores to the housing structure. The plurality of mechanical supports may be further configured to output heat from the stator structure.

[0135] The toroidal winding in the apparatus described in any one or more of the six paragraphs above may include a flat strip made of multiple strands of wire and placed in the stator core slots. The strip may be made of Litz wire construction, or the strands of wire may have a rectangular cross-section to minimize ohmic losses. The position of each wire strand within the strip may be varied with respect to the respective stator core slots in order to minimize the proximity effect and, in turn, the ohmic losses.

[0136] The apparatus described in any one or more of the above seven paragraphs may have a stator structure and a rotor structure arranged to maximize axial flux and / or radial flux.

[0137] A device as described in the previous paragraph, wherein (1) N=2, wherein N stator cores and N rotor cores are arranged to form a double air gap radial flux machine; (2) N=2, wherein N stator cores and N rotor cores are arranged to form a double air gap axial flux machine; (3) N=3, wherein N stator cores and N rotor cores are arranged to form a three air gap flux machine, which three air gap flux machine includes two axial air gaps and one radial air gap or one axial air gap and two radial air gaps; (4) N=4, wherein N stator cores and N rotor cores are arranged to form a five air gap flux machine, which five air gap flux machine includes two axial air gaps and three radial air gaps, or three axial air gaps and two radial air gaps; or (5) N stator cores and N rotor cores are arranged to form a multi-air gap machine, wherein the air gaps are continuous, wherein the multi-air gap flux machine can be configured as a linear machine.

[0138] All patents, patent applications, and publications cited herein are hereby incorporated by reference for all purposes as if expressly set forth.

[0139] While the invention has been described in conjunction with what are presently considered to be the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, but on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A magnetic transmission device configured as a motor or a generator and comprising a stator structure and a rotor structure configured to improve torque generation, wherein: The stator structure comprises N>1 stator cores and a shared annular electrical winding; as well as The rotor structure includes an equal number of corresponding rotor cores.

2. A magnetic transmission device according to claim 1, wherein the device is a vernier machine.

3. The magnetic transmission device according to claim 2, wherein the N stator cores are arranged back to back.

4. The magnetic transmission device of claim 3, wherein a respective cold plate and one or more cooling channels are provided between each pair of back-to-back stator cores.

5. The magnetic transmission device of claim 4, wherein the respective cold plates include one or more cooling channels.

6. The magnetic transmission device according to claim 3, wherein the N stator cores are integrated into a single core.

7. The magnetic transmission device of claim 1, further comprising one or more thermal channels configured to transfer heat away from the stator structure.

8. The magnetic transmission device of claim 1, further comprising a housing structure and a plurality of mechanical supports configured to connect the N stator cores to the housing structure.

9. The magnetic transmission device of claim 8, wherein the plurality of mechanical supports are further configured to output heat away from the stator structure.

10. The magnetic transmission device of claim 1 further comprising a plurality of magnets arranged in a Halbach configuration and attached to the at least one rotor core. 11 . The magnetic transmission device of claim 1 , wherein the N stator cores and / or the N rotor cores are configured to reduce eddy currents.

12. The magnetic transmission device of claim 1, wherein the electrically insulating ferromagnetic laminations are arranged with the lamination direction normal to the air gap surface and normal to the direction of motion of the rotor relative to the stator, thereby limiting eddy currents in the stator and rotor cores.

13. The magnetic transmission device according to claim 1, wherein the N rotor cores and / or the N stator cores are formed of ferromagnetic particles electrically insulated from each other, thereby limiting eddy currents within the rotor and / or the stator cores.

14. The magnetic transmission machine of claim 1, wherein the N stator cores include stator core teeth arranged in a substantially open slot configuration for flux modulation.

15. The magnetic transmission device of claim 1, wherein the N stator cores include split-tooth flux modulators.

16. The magnetic transmission device of claim 1, wherein said N stator cores are substantially fused within said stator structure and / or said N rotor cores are substantially fused within said rotor structure such that said annular winding is substantially surrounded by the substantially fused stator and / or substantially fused rotor.

17. The magnetic drive device of claim 1, wherein the annular winding comprises a flat strip made of multiple strands of wire and disposed within stator core slots.

18. A magnetic transmission device according to claim 17, wherein the belt is made of a Litz wire arrangement.

19. The magnetic actuator of claim 17 wherein each of said strands of said electrical wire has a rectangular cross-section to minimize ohmic losses.

20. The magnetic drive device of claim 17 wherein the position of each of said strands of said wire within said band is varied with respect to a respective stator core slot so as to minimize proximity effects and thereby minimize ohmic losses.

21. The magnetic transmission device of claim 1, wherein the stator structure and the rotor structure are arranged to maximize axial flux and / or radial flux.

22. The magnetic transmission device of claim 1, wherein N=2, and wherein the N stator cores and the N rotor cores are arranged to form a double air-gap radial flux machine.

23. A magnetic transmission device according to claim 22, wherein three of the four sides of the toroidal winding are cooled.

24. The magnetic transmission device of claim 1, wherein N=2, and wherein the N stator cores and the N rotor cores are arranged to form a double air-gap axial flux machine.

25. The magnetic transmission device according to claim 1, wherein N=3, and wherein the N stator cores and the N rotor cores are arranged to form a three-gap flux machine, the three-gap flux machine comprising two axial air gaps and one radial air gap or one axial air gap and two radial air gaps.

26. The magnetic transmission device of claim 1, wherein N=4, and wherein the N stator cores and the N rotor cores are arranged to form a five-gap flux machine, the five-gap flux machine comprising two axial air gaps and three radial air gaps or three axial air gaps and two radial air gaps.

27. The magnetic transmission device of claim 1, wherein said N stator cores and said N rotor cores are arranged to form a multi-air-gap machine, wherein said air gap is continuous.

28. The magnetic transmission device of claim 27, wherein the multiple air-gap flux machine is configured as a linear machine.

29. The magnetic actuator of claim 17, wherein the plurality of air gaps are combined into a single combined air gap.

30. The magnetic actuator of claim 1 wherein said toroidal winding is a printed circuit board (PCB) winding.

31. A magnetic drive double air gap device configured as a motor or generator and comprising a stator structure and a rotor structure to improve torque production, wherein: The stator structure comprises two stator cores and a common annular electric winding; and The rotor structure comprises 2 respective rotor cores, wherein the stator core and the rotor core are arranged to form a double air gap radial flux machine or a double air gap axial flux machine.

32. A magnetic drive triple air gap device configured as a motor or generator and comprising a stator structure and a rotor structure to improve torque production, wherein: The stator structure comprises three stator cores and a common annular electrical winding; and The rotor structure comprises three corresponding rotor cores, wherein the stator core and the rotor core are arranged to form a three-gap flux machine comprising two axial air gaps and one radial air gap, or one axial air gap and two radial air gaps.

Images