Electric machine system and method

Abstract

An electric machine includes a rotor body defining a rotor axis, the rotor body including a back iron, a plurality of handles extending radially away from the back iron, and a plurality of pole caps each removably coupled to a respective one of the plurality of handles. The back iron, the handle and the pole cap may be made of different materials, and the rotor may be re-magnetized to change the number of poles of the motor. A pre-tensioned retention wrap is provided to help secure the rotor components together and allow for increased rotor speed. A retention body is positioned between the rotor body and the retention wrap to compensate for thermal expansion and maintain the retention wrap within a predetermined tension range.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 467,512, filed May 18, 2023; U.S. Provisional Patent Application No. 63 / 536,302, filed September 1, 2023; and U.S. Provisional Patent Application No. 63 / 553,029, filed February 13, 2024, each of which is incorporated herein by reference in its entirety.

[0003] Explanation of federally sponsored research or development

[0004] not applicable. Background Technology

[0005] This disclosure generally relates to systems and methods for electric motors, and more specifically, to arrangements and manufacturing methods for multi-material rotors, as well as rotor retention systems and rotors with reconfigurable poles. Summary of the Invention

[0006] According to one aspect of this disclosure, a rotor for an electric motor is provided. The rotor may include a rotor body and rotor windings. The rotor body may define a rotor axis and a plurality of teeth extending radially away from the rotor axis. The rotor body may include a back iron, a plurality of shanks, and a plurality of pole caps. The plurality of shanks may extend radially away from the back iron, and each of the plurality of shanks may correspond to one of the plurality of teeth. The plurality of pole caps may be removably coupled to a corresponding one of the plurality of shanks. The rotor windings may be wound around the plurality of teeth.

[0007] In some examples, multiple pole caps may be made of a first material, and one or more shanks of the back iron may be made of a second material different from the first material. In some cases, the first material may be electrical steel, and the second material may be carbon steel. In some cases, the back iron may be made of a second material, and multiple shanks may be made of a third material.

[0008] In some examples, the back iron may have a first grain orientation, and the multiple shanks may have a second grain orientation. In some cases, the first grain orientation is oriented circumferentially relative to the rotor axis, and the second grain orientation is oriented radially relative to the rotor axis.

[0009] According to another aspect of this disclosure, an electric motor is provided. The electric motor may include a stator and a rotor configured to rotate relative to the stator. The rotor may include a rotor body, rotor windings, a retaining winding, and a compliant member. The rotor body may define a plurality of teeth, and the rotor windings may be wound around the plurality of teeth. The retaining winding may be wound around the rotor body and configured to apply a compressive force to retain the rotor windings on the rotor body. The compliant member may be configured to maintain the retaining winding within a predetermined tension range.

[0010] According to another aspect of this disclosure, an electric motor with reconfigurable poles is provided. The motor may include a stator and a rotor configured to rotate relative to the stator. The rotor may include a plurality of rotor windings wound around corresponding plurality of teeth extending from a rotor core. The rotor core may be made of a magnetizable material and may be configured to be selectively magnetized into a first pole configuration having a first number of poles and a second pole configuration having a second number of poles different from the first number of poles.

[0011] According to another aspect of this disclosure, a rotor assembly for an electric motor is provided. The rotor assembly includes: a rotor shaft having a flange disposed at an end of a rotor shaft; a rotor body coupled to the rotor shaft; and rotor windings supported on the rotor body. The rotor assembly further includes a balancing ring for retaining the rotor windings on the rotor body. The balancing ring defines an inner lip, on which the flange is bent to retain the rotor windings on the rotor shaft. Attached Figure Description

[0012] The invention will be better understood when considering the following specific embodiments, and features, aspects, and advantages in addition to those described above will become apparent. This specific embodiment is illustrated in the following figures.

[0013] Figure 1 This is a schematic diagram of an electric motor including a stator and a rotor according to various aspects of this disclosure.

[0014] Figure 2 for Figure 1 Exploded view of the motor.

[0015] Figure 3 for Figure 1 A cross-sectional view of the first rotor configuration.

[0016] Figure 4 for Figure 1 A cross-sectional view of the second rotor configuration.

[0017] Figure 5 for Figure 1 A cross-sectional view of the third rotor configuration.

[0018] Figure 6 for Figure 1 A cross-sectional view of the fourth rotor configuration.

[0019] Figure 7 To show the passage Figure 1 A partial schematic diagram of the magnetic flux path of the rotor.

[0020] Figure 8 This is a cross-sectional view of a rotor with six rotor poles in the first configuration.

[0021] Figure 9 For the second configuration with two rotor poles Figure 8 A cross-sectional view of the rotor.

[0022] Figure 10 This is a schematic diagram of a rotor with eight rotor poles in the first configuration.

[0023] Figure 11 For the second configuration with four rotor poles Figure 10 A schematic diagram of the rotor.

[0024] Figure 12 For the third configuration with two rotor poles Figure 10 A schematic diagram of the rotor.

[0025] Figure 13 A partial perspective view of a bobbin winding mounted on a rotor, which includes a circumferentially retained winding.

[0026] Figure 14 A partial side view of a rotor with axially retained windings.

[0027] Figure 15 for Figure 14 A partial top view of the rotor.

[0028] Figure 16 To show Figure 14 Schematic diagrams of various aspects of the rotor.

[0029] Figure 17 To illustrate the stress distribution in the bonded pole cap.

[0030] Figure 18 To illustrate the stress distribution in the unbonded pole cap.

[0031] Figure 19 A perspective view of the rotor winding fixed in a compliant component configured as a cooling tank.

[0032] Figure 20 This is a partial cross-sectional view of rotor teeth with pole caps having angled inner surfaces.

[0033] Figure 21 A cross-sectional view of a rotor having a balance ring fixed by the rotor shaft.

[0034] Figure 22 for Figure 21 A front equidistant view of the rotor shows the balance ring fixed to the rotor shaft.

[0035] Figure 23 for Figure 21 A rear isometric view of the rotor, showing the balance ring fixed to the rotor shaft. Detailed Implementation

[0036] Before providing a detailed description of any embodiment of the invention, it should be understood that the invention is not limited to applying it to the structural details and component arrangements described in the following specification or drawings. The invention is capable of having other embodiments and can be practiced or implemented in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The terms "including," "comprising," or "having," and variations thereof, as used herein, are intended to cover the items listed thereafter and their equivalents, as well as additional items. Unless otherwise specified or limited, the terms "installation," "connection," "support," and "coupling," and variations thereof, are used broadly and cover direct and indirect installation, connection, support, and coupling. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings.

[0037] As used herein, the term "about" refers, for example, to a variation in numerical quantity that may occur through typical measurement and manufacturing processes used for footwear articles or other articles that may include embodiments of the present disclosure; through unintentional errors in these processes; through differences in the manufacture, origin, or purity of the ingredients used to manufacture the composition or mixture or to implement the method, etc. Throughout the disclosure, the terms "about," "substantially," and "approximately" refer to a range of ±5% of the value of the numerical value following that term.

[0038] The following discussion is provided to enable those skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the general principles herein can be applied to other embodiments and applications without departing from the embodiments of the invention. Therefore, embodiments of the invention are not intended to be limited to the illustrated embodiments, but are to conform to the widest scope consistent with the principles and features disclosed herein. The following detailed description should be read with reference to the accompanying drawings, in which the same elements in the different drawings have the same reference numerals. The drawings, not necessarily drawn to scale, illustrate selected embodiments and are not intended to limit the scope of embodiments of the invention. Those skilled in the art will recognize that the examples provided herein have many useful alternatives and that fall within the scope of embodiments of the invention.

[0039] An electric motor can be used to convert electrical potential energy into kinetic energy that can be used to perform work. In some motors, such as electric motors or generators, the motor includes a stationary component (e.g., a stator) and a rotating component (e.g., a rotor). In an electric motor, current is converted into an electromagnetic field, applying a mechanical force or torque between the stator and rotor that can be used to do work. Generators operate on a similar principle to electric motors, but in which mechanical force is converted into current. Although primarily described in terms of rotational force or torque, the principles described herein also apply to linear motors. For example, in some linear motors, the rotor serves as the stationary component, while the stator serves as the switching component.

[0040] A rotor for an electric motor may include a rotor body defining a rotor axis. The rotor body typically includes a back iron and a plurality of teeth extending radially from the back iron relative to the motor axis. The teeth are configured to receive and retain windings that can be energized to generate a rotor magnetic field that interacts with the stator magnetic field, thereby causing rotation of the rotor. More specifically, each tooth may include a shank extending from the back iron around which the windings can be wound, and a pole cap is coupled at the distal end of the shank, the pole cap being configured to retain the windings on the rotor body during rotor rotation.

[0041] In conventional designs, the rotor body can be made from multiple stamped or laser-cut laminations stacked together (e.g., in the axial direction) to form the rotor body. Each lamination is a monolithic structure made of a single piece of material (e.g., electrical steel), meaning the rotor body is essentially made of a single material (although insulating layers can be placed between the laminations to help reduce eddy currents during dynamic magnetic loading). Thus, each lamination forms a corresponding axial slice of the rotor body, which includes a portion of the back iron and each of the multiple teeth (e.g., the shank and pole cap). While using monolithic laminations simplifies the construction of the rotor body, it can also lead to performance losses because different regions of the rotor body experience different levels or rates of flux change during normal operation, and the rotor material may be selected only according to the needs of a specific region (e.g., using electrical steel for the entire rotor body due to rapid flux changes at the pole cap).

[0042] Accordingly, specific rotor designs may introduce certain trade-offs. For example, in wound-fed synchronous motors (WFSMs), there is a trade-off between the copper area and the steel area within a given WFSM rotor diameter. More copper generally allows for higher rotor excitation within a given current density limit, resulting in higher torque / ampere, but the reduced steel area can lead to higher magnetic flux density and rotor magnetic saturation, and also increased mechanical stress in the steel due to centripetal acceleration. Therefore, depending on the rotor design, a high-performance motor may be limited to its maximum operating speed due to the increasing rotational inertial stress in the rotor with increasing speed square, or due to the tendency of soft-annealed copper windings to plastically deform outward at high speeds.

[0043] In some cases, to achieve improved performance (e.g., efficiency, torque output), WFSMs can be combined with permanent magnet-based or permanent magnet-assisted rotors, which may employ expensive, high-coercivity, low-permeability magnets (e.g., neodymium magnets). However, these magnets may be designed to be too large for peak torque conditions and to account for performance degradation as the magnet heats up. Furthermore, the permanent magnetization state of these magnets is fixed and cannot be changed in response to operating conditions. While induction motors can be robust and inexpensive to manufacture, they also have several drawbacks: lower power factor and efficiency under light load conditions; difficulty in speed control due to the machine's inherently constant-speed nature; and relatively poor starting torque.

[0044] Therefore, this disclosure provides alternative rotor arrangements and configurations that, compared to conventional rotor designs (including those with and without permanent magnets), enable improved performance (e.g., peak torque, starting torque, efficiency, etc.) over a wide range of operating conditions. For example, the rotor can be constructed as a multi-material rotor body without relying on a conventional monolithic lamination stack. Instead, the individual structures of the rotor body can be made as independent components (e.g., as a lamination stack or using other construction methods), and these components can be interconnected to form the rotor body, as generally described below.

[0045] Therefore, each component of the rotor body can be made of a material selected according to the electromagnetic requirements of that particular component. For example, the pole cap can be made of a first material configured to withstand the rapidly changing magnetic field and temporary magnetization experienced by the pole cap (e.g., a material with low hysteresis and high permeability, such as electrical steel), while the rotor back iron or shank can be made of a second material configured to be magnetized or have oriented grains to control the magnetic flux through the rotor body between the rotor poles (e.g., a material with relatively high hysteresis and low permeability, such as carbon steel).

[0046] Figure 1 and Figure 2A non-limiting example of an electric motor 100 is shown. The electric motor 100 can be configured as a wound-rotor synchronous motor, comprising a stator 102 and a rotor 104 configured to rotate relative to the stator 102; however, the principles described herein are equally applicable to other types of motors. As generally described above, current can be supplied to the windings in the stator 102 to generate a (rotating) stator magnetic field. Accordingly, current can be applied to the windings in the rotor 104 to generate a rotor magnetic field that interacts with the stator magnetic field. More specifically, the stator magnetic field interacts with the rotor magnetic field, thereby generating a pushing and / or pulling force on the rotor 104, causing the rotor 104 to rotate relative to the stator 102. The rotor 104 includes a rotor shaft 106 that defines a rotor axis 108. The rotor 104 and stator 102 are concentrically aligned about the rotor axis 108, and the rotor 104 is removably coupled to rotate about the rotor axis 108 within an internal cavity 110 of the stator 102. In some examples, rotor 104 may also include one or more permanent magnets that help to form a rotor magnetic field and also interact with the stator magnetic field to cause rotation of rotor 104.

[0047] As generally described below, a rotor can be constructed as a multimaterial rotor. A multimaterial rotor may include one or more separate components that are joined together to form the multimaterial rotor. Accordingly, the various components of a multimaterial rotor may be made of different types of materials, including, for example, steel (e.g., electrical steel, carbon steel, martensitic steel), aluminum, plastics, rubber, foamed plastics, and fiber-reinforced composite materials such as glass fiber or carbon fiber.

[0048] In some cases, the rotor may include a multi-material rotor body configured to support the rotor windings. The rotor body can be constructed in various ways to achieve desired performance characteristics, efficiency, etc. Therefore, further consideration is needed. Figure 3-6 The rotor 104 (e.g., rotors 104A-D) typically includes a rotor core or rotor body 202. The rotor body 202 may be arranged to receive a rotor shaft (e.g., rotor shaft 106). For example, the back iron 204 may define an opening 203, and the rotor shaft 106 may be inserted into the opening 203, thereby enabling the rotor body 202 to be coupled to the rotor shaft 106.

[0049] The rotor body 202 may support the rotor windings and may include a back iron 204 (e.g., defining an opening 203) and a plurality of teeth 208 extending radially away from the rotor axis 108 to support the rotor windings 214. In the non-limiting example shown, the rotor 104 includes six teeth; however, other configurations may have different numbers of teeth (e.g., two, four, eight, etc.). Each tooth 208 includes a shank 206 coupled to the back iron 204 and extending radially away from the back iron 204, and a pole cap 210 coupled to a radially distal end 212 of the shank 206. In other words, the rotor body 202 typically includes a plurality of shanks 206 and a plurality of pole caps 210 that together form the plurality of teeth 208.

[0050] As mentioned above, the rotor teeth can be configured to receive and retain the rotor windings. Figure 3-6 As shown, the rotor 104 includes a rotor winding 214 wound around each tooth 208 (e.g., via a bobbin winding structure). More specifically, each winding 214 is wound around one of the shanks 206 and secured to the shank 206 by a pole cap 210. Thus, the shank 206 can have a chord length 216 smaller than the chord length 218 of the pole cap 210. The chord length is a dimension taken perpendicular to the radial and axial directions of the rotor (e.g., the tangential direction). In this way, the pole cap 210 can define an overhand relative to the corresponding shank 206, which helps to retain the winding 214 on the rotor body 202 during rotor rotation.

[0051] The back iron, shank, and pole cap of the rotor body can be connected in various ways, including, for example, through direct mechanical connection between adjacent components, indirect connection via a fastening system, or integrally formed together (e.g., as a monolithic substructure). Accordingly, the connection between two or more components can be permanent or removable. Additionally, any one of the back iron, shank, and pole cap can be formed as a stack or monolithic structure (e.g., as a single, solid piece of material).

[0052] For example, in some cases, the back iron and multiple shanks can together define the rotor core. For instance... Figure 3-5 As shown, the shank 206 is integrally formed with the back iron 204 to form the rotor core 202. In this case, the rotor core 202 is formed as a stack of laminations having multiple laminations stacked in the axial direction. Accordingly, each lamination is formed as an integral lamination, which includes a corresponding back iron 204 and a shank 206. Thus, each shank 206 extends integrally from the back iron 204 and is radially away from the rotor axis 108.

[0053] However, in some cases, the shank and back iron are formed separately. For example, as shown in... Figure 6As shown, each shank 206 is formed separately from and connected to the back iron 204. More specifically, a mechanical interlock 220 is formed between each shank 206 and the back iron 204, which is configured as a dovetail connection to secure the shank 206 to the back iron 204. Furthermore, the back iron 204 can be constructed as a segmented back iron, having multiple back iron segments 222 connected together (e.g., via mechanical interlock). In this case, each shank 206 is connected to a corresponding back iron segment 222. In other non-limiting examples, a similar principle can be applied to other rotor components (e.g., shanks and pole caps), which can also be segmented.

[0054] Accordingly, the pole cap can be formed as a separate component attached to the shank (e.g., the rotor core). Figure 3 As shown, each pole cap 210 is configured as a separate component to be coupled to a corresponding handle 206. In this example, each pole cap 210 is coupled to a corresponding handle 206 via a direct mechanical interlocking connection 224. Specifically, each handle 206 includes a protrusion 230 configured to be received in a slot 232 defined by the pole cap 210 (or vice versa). The protrusion 230 is positioned at the distal end of the handle 206 opposite to the proximal end of the handle 206, which is coupled to the back iron 204. The protrusion 230 and the slot 232 are complementary in shape and configured such that when the pole cap 210 is coupled to the handle 206, the interlock between them resists disengagement of the pole cap 210 from the handle 206 due to the centripetal force experienced during rotation. In the illustrated example, the protrusion 230 includes opposing lateral flanges 229 that extend from the base 231 of the protrusion 230 (e.g., circumferentially or otherwise substantially perpendicular to the radial direction). Each flange 229 is received in a chamfer 233 (e.g., a channel) within a recess 235 defined in the slot 232. In other examples, the protrusion 230 and the slot 232 are configured with different specific shapes. In this way, the mechanical interlocking connection 224 can operate similarly to a dovetail connection, and the winding 214 can also be retained on the rotor body 202.

[0055] In other non-limiting examples, the pole caps may be retained on the shank in other ways. Specifically, the rotor may include a fastening system configured to secure the pole caps to the shank. For example, as... Figure 4As shown, the pole cap 210 can be secured to the shank 206 by fasteners 234 (e.g., pins, threaded rods, nuts, and bolts). More specifically, the shank 206 can define an orifice 236 that can be aligned with a corresponding orifice on the pole cap 210, allowing the fasteners 234 to be inserted therein. In this way, the fasteners 234 can form a pin-fit connection between the protrusion 230 and the slot 232 to securely fasten the pole cap 210 to the plurality of shanks 206 and retain the winding 214 on the rotor body 202. As another non-limiting example, such as Figure 5 As shown, the pole cap 210 can be secured to the shank 206 by a retaining winding 240. The retaining winding 240 is typically configured to be wound around the outer periphery of the rotor core 202 to apply radial compression between the pole cap 210 and the shank 206. Additional details of the retaining winding will be described in more detail below.

[0056] Because the pole caps can be formed separately from the shank (i.e., the rotor core), windings can be mounted on the rotor more easily compared to conventional rotor designs. This allows for more compact windings, resulting in improved efficiency and power density. More specifically, in conventional windings, the pole caps are not removable, and the windings must be wound in place around each rotor tooth (e.g., around the shank and below the pole cap). However, as... Figure 3-6 As shown, since the pole caps 210 of rotors 104A-D are removable from the shank 206, the windings 214 can be wound around the shank 206 before the pole caps 210 are fixed. Alternatively, the removability of the pole caps 210 also allows the shank 206 to receive pre-made windings.

[0057] More specifically, the pre-made winding can be a spool-wound winding. Spool winding is a process in which the winding (i.e., the wires constituting the winding) is wound on a separate spool before being mounted onto the shank 206. The spool winding process allows for a higher copper slot fill factor (i.e., fill ratio or fill fraction) in at least some examples, for example, because it allows the slots to be completely filled without concern for interference between the geometry of the winding machine and the rotor core 202 (e.g., the pole cap or shank). Furthermore, this process allows for compression of the winding before mounting onto the shank 206, which is difficult, if not impossible, for conventional rotor designs that require in-situ winding. For this purpose, spool-wound and compressed windings can achieve a slot copper fill factor of approximately 70%, while in-situ winding typically only achieves a fill fraction between approximately 50% and 60%. This increase in winding density enables higher winding densities, resulting in motors with higher power density and higher efficiency. Furthermore, since the winding of the bobbin can be done separately from its mounting on the rotor, parallel installation can be easily achieved during manufacturing and assembly, whereas in-situ winding cannot, resulting in a shorter cycle time.

[0058] The formation of integral and discrete components allows for the use of different materials in different regions of the rotor. For example, electrical steel can be selectively used in regions subjected to strong or rapidly changing magnetic fields (e.g., in or near the air gap between the rotor and stator, such as at the pole caps). Electrical steel typically has a high silicon content (e.g., up to about 6.5% silicon, or more specifically about 1% to about 3%, about 2% to 5%, or about 3% to about 6.5%, or any range thereof), which increases resistivity and thus reduces eddy currents and their associated losses (e.g., core losses in the rotor core). Furthermore, electrical steel typically has a low carbon content (e.g., less than 0.05% carbon, or more specifically, less than about 0.01% carbon, or less than about 0.005% carbon, or any range thereof), which reduces hysteresis losses and increases permeability.

[0059] As mentioned earlier, electrical steel can reduce eddy currents and losses caused by rapid changes in magnetic flux. Therefore, in some examples, the rotor core can be made entirely of electrical steel. However, because rapid changes in magnetic flux are more common in certain regions of the rotor core, in some examples, electrical steel is used in these regions, while other materials are used in regions where less rapid changes in magnetic flux are more likely to occur. For example, as... Figure 7 As shown, since this rapid change in magnetic flux 250 is primarily dominated by the passage of stator teeth / slots and is generally confined to the region very close to the air gap 252 between rotor 104 and stator 102 (e.g., in pole cap 210), most of the rotor flux is substantially constant (e.g., in shank 206 and back iron 204). Accordingly, carbon steel can be used, for example, in the rotor core where the flux is generally constant, or in regions where selective magnetization, depending on operating conditions, can help improve rotor performance (e.g., in shank or back iron). Carbon steel typically has a high carbon content (e.g., between about 0.4% and about 4% carbon, between about 0.4% and about 2%, between about 2% and about 4%, between about 1% and about 3%, or any range between about 0.4% and about 4%) and is generally cheaper than electrical steel. Therefore, by selectively combining electrical steel and carbon steel in certain configurations, a more efficient rotor body with higher power density can be produced compared to conventional rotor constructions.

[0060] For example, such as Figure 3-5 and Figure 7As shown, the shank 206 and back iron 204 together form the rotor core 202 and are positioned away from the air gap 252, and can be made of carbon steel (e.g., as a lamination stack). The back iron 204 and shank 206 provide a relatively long arc length 251 for the magnetic flux 250, which can induce a significant magnetomotive force (MMF) even at the low coercivity achievable with carbon steel. Accordingly, the pole cap 210, positioned immediately adjacent to the air gap 252 (e.g., between the rotor core 202 and the air gap 252), can be formed of electrical steel (e.g., as a lamination stack) because during operation, the pole cap 210 tends to experience a larger flux change compared to the shank 206 and back iron 204, and its corresponding magnetic flux 250 has a shorter arc length 253.

[0061] In addition to helping improve motor performance and efficiency through optimal or targeted material usage, the use of carbon steel in the rotor core can further improve performance by allowing the rotor to be remagnetized and to change the number of rotor poles (i.e., the magnetic poles of the rotor). That is, as discussed in general above, the selective magnetization and demagnetization capabilities of carbon steel enable the (instantaneous) reconfiguration of the number of poles during motor operation. Therefore, according to some examples of this disclosure, multi-material rotors can be selectively remagnetized to multiple pole configurations with different numbers of poles, including a number of poles that may differ from the number of teeth. This reconfigurability contrasts with rotor cores that use only electrical steel. Such rotor cores are typically not remagnetized and have a fixed number of poles equal to the number of rotor teeth.

[0062] To control reconfigurability, the motor may include a controller configured to switch between a first-pole configuration and a second-pole configuration based on motor operating parameters such as speed command or output, torque command or output, operating temperature, etc. In some cases, the controller can re-flux the rotor by controlling the energization of the stator windings. For example, the stator may include stator windings, and the controller may be configured to control the current flow in the stator windings to induce a corresponding current in the rotor core to switch the rotor core between the first-pole and second-pole configurations.

[0063] Accordingly, the rotor can be refluxed to have a specific number of poles, which can be selected based on the rotor's operating parameters or conditions (e.g., speed, torque output, etc.) or the vehicle's operating parameters or conditions (e.g., vehicle speed, drive mode, traction / towing mode, gradient, commanded acceleration, etc.). Therefore, different numbers of rotor poles can provide enhanced performance under different operating conditions. Specifically, a higher number of poles generally results in higher torque, which is particularly useful at low speeds (e.g., at low vehicle speeds and low rotor speeds), during high acceleration, or when driving uphill or traction / towing loads. However, at high speeds, a higher number of poles typically generates a higher back EMF current in the stator, which can limit the maximum achievable speed, increase temperature, or degrade motor performance. Conversely, a lower number of poles generally favors low torque, high-speed operation, which is common during highway driving. This is because a lower number of poles typically generates a relatively smaller back EMF current in the stator, allowing for higher speeds while maintaining high motor efficiency.

[0064] Generally, rotors have an even number of poles so that each north pole corresponds to a south pole. For example, Figure 8 and Figure 9 A rotor 104 with six teeth 208 is depicted, which can be refluxed into two configurations. Figure 8 In the first configuration shown (e.g., a high-torque or low-speed configuration, such as greater than half the rated torque or less than half the rated motor speed), the rotor 104 is refluxed to a first number of poles with six rotor poles. In the first configuration, each tooth 208 defines a north pole 260 or a south pole 262, and the polarities of adjacent shanks 206 are different from each other. In other words, the polarities of the teeth 208 are in an alternating pattern, with a total of three north poles and three south poles, wherein each north pole has a corresponding south pole on a radially opposite side of the rotor 104. Therefore, due to the attraction between different polarities and the repulsion between like polarities, the flux 264 in one tooth extends to each adjacent tooth with the opposite polarity.

[0065] However, in Figure 9In the second configuration shown (e.g., for low torque or high speed configurations, such as less than half the rated torque or greater than half the rated motor speed), the rotor 104 can be refluxed to a different number of second poles with two poles. In this second configuration, teeth with the same polarity are grouped together to form a first pole 260 on the first half of the rotor (e.g., a first semi-cylindrical region of the rotor comprising three adjacent teeth 208) and a second pole 262 on the corresponding second half of the rotor (e.g., a second semi-cylindrical region of the rotor comprising three adjacent teeth 208). Here, the first pole 260 comprises three adjacent teeth 208, each tooth 208 having a north pole polarity, and the second pole 262 similarly comprises three adjacent teeth 208, each tooth 208 having a south pole polarity. Therefore, in this configuration, the magnetic flux 264 through the rotor 104 typically extends from the second pole 262 to the first pole 260.

[0066] Additionally, as a non-restrictive example, Figure 10-12 A rotor 104 with eight teeth 208 is depicted, which can be reconfigured into three different configurations. Figure 10 In the first configuration shown (e.g., a high-torque or low-speed configuration, such as greater than two-thirds of the rated torque or less than one-third of the rated motor speed), the rotor 104 is refluxed to a first number of poles with eight rotor poles, such that each tooth 208 defines a north pole 260 or a south pole 262, wherein the polarities of adjacent shanks 206 are different from each other. In other words, the polarities of the teeth 208 are in an alternating pattern, with a total of four north poles and four south poles, wherein each north pole has a corresponding south pole on a radially opposite side of the rotor 104.

[0067] exist Figure 11 In the second configuration shown (e.g., a medium torque or medium speed configuration, such as between one-third and two-thirds of the rotor torque or motor speed), the rotor 104 is refluxed to a second number of poles with four poles. In this second configuration, two adjacent teeth are grouped together to form a pole in each quadrant of the rotor 104. More specifically, the rotor 104 has a first quadrant defining a first north pole 260, a second quadrant defining a first south pole 262, a third quadrant defining a second north pole 260, and a fourth quadrant defining a second south pole 262, and these quadrants are arranged in an alternating pattern around the rotor 104. Thus, in this second configuration, the magnetic flux 264 through the rotor 104 generally extends from one tooth to each adjacent tooth (i.e., from the tooth adjacent to one of the south poles 262 to the tooth adjacent to one of the north poles 260), such that the magnetic flux entering the south pole is distributed to each of the two adjacent north poles. For example, the magnetic flux entering the first tooth of the South Pole usually flows to the first North Pole, while the magnetic flux entering the second tooth of the South Pole usually flows to the second North Pole, which is opposite to the first North Pole.

[0068] exist Figure 12 In the third configuration shown (e.g., a low-torque or high-speed configuration, such as less than one-third of the rated torque or greater than two-thirds of the rated motor speed), the rotor 104 is refluxed to two different third pole numbers. Figure 9 Similarly, in this third configuration, teeth 208 of the same polarity are grouped together to form a first pole 260 on the first half of the rotor (e.g., the first semi-cylindrical region of the rotor) and a second pole 262 on the corresponding second half of the rotor (e.g., the second semi-cylindrical region of the rotor). Here, the first pole 260 is defined by four adjacent teeth 208, while the remaining four adjacent teeth 208 define the second pole 262. Therefore, in this third configuration, the magnetic flux 264 through the rotor 104 typically extends from the second pole 262 to the first pole 260.

[0069] In some cases, different material arrangements of the rotor can be used to enhance motor performance in other ways. Specifically, grain-oriented steel (GOES, grain-oriented electrical steel) and non-grain-oriented steel (NGOES, non-grain-oriented electrical steel) can be used in different regions of the rotor, depending on (e.g., approximating) the optimal or target magnetic flux path through the rotor. NGOES steel has randomly oriented magnetic grains that do not provide a preferred or optimal direction for the magnetic flux. Therefore, the magnetic flux passing through the rotor core in a specific direction is not particularly aided or hindered by the grains—NGOES provides an overall neutral effect on the magnetic flux. Thus, NGOES can improve the efficiency of rotor operation in situations where the flux lines may not be well aligned in a single direction (e.g., at the pole cap) or are dispersed.

[0070] Compared to NGOES, GOES has magnetic grains aligned in a specific direction, resulting in magnetic properties aligned with a preferred orientation (e.g., to increase permeability along a specific direction). This grain orientation helps guide magnetic flux through the rotor along a desired path, leading to more efficient rotor operation. Furthermore, GOES can increase the magnetic flux density within the rotor, for example, by approximately 30% compared to NGOES. However, due to the grain orientation, GOES may exhibit greater losses when the magnetic flux does not travel along the grain direction. Therefore, GOES can be advantageously applied in situations where the magnetic flux direction is substantially constant along a known direction, such as in the shank and back iron.

[0071] Some rotor cores may comprise an integral structure consisting entirely of NGOES or entirely of GOES. However, in some examples, the rotor is provided as a combination of GOES and NGOES, each positioned in specific locations within the rotor core to achieve more efficient rotor operation. For example, the rotor core may include NGOES in areas where the flux lines may not be well aligned in a single direction (e.g., at the pole cap) or where the flux line density may be low. Additionally, the rotor core may include GOES in areas where the flux lines are aligned or have a relatively high density, such as in the shank and back iron. Such a combination allows for the utilization of the advantages of both GOES and NGOES while avoiding those aspects of GOES and NGOES that might reduce or limit efficiency.

[0072] For example, see Figure 6 and Figure 7 The orientation of grains can essentially align the magnetic properties of a material with the flux lines, thereby increasing the flux density and allowing for higher torque within a given current density limit, or reducing the required current density by decreasing the rotor core area and increasing the copper area (e.g., winding area). For example, Figure 7 It is shown that the flux lines 250 generally extend between the back iron 204 and the pole cap 210 in a direction substantially perpendicular (e.g., circumferential and / or radial) to the length 216 of the shank 206. Therefore, as Figure 6 As shown, the shank 206 may have a first grain orientation 268 along a first direction (e.g., the radial direction relative to the rotor axis 108) to be substantially parallel to the optimal magnetic flux path in the shank 206. Similarly, the magnetic flux lines generally extend in a circumferential or tangential direction within the back iron 204. Therefore, each back iron segment 222 may have a second grain orientation 270 that is substantially circumferential or tangential relative to the rotor axis 108. In this way, the back iron segments 222 can collectively approximately form a circumferential grain orientation in the back iron 204. Accordingly, the grain orientation of the back iron segments 222 and the grain orientation of the shank 206 may be substantially orthogonal to each other.

[0073] As described above, in some cases, retaining windings can be used to help hold rotor components together, enabling multi-material rotors to operate at higher speeds (e.g., greater than approximately 15,000 revolutions per minute). The retaining windings can be thinner relative to the radial direction of the rotor to minimize the impact on the air gap and thus on electromagnetic properties (e.g., between approximately 0.2 mm and approximately 5 mm, approximately 0.2 mm and approximately 1 mm, approximately 0.2 mm and approximately 2 mm, or approximately 0.2 mm and approximately 3 mm, depending on specific operating conditions). However, thicker windings can generally also apply greater forces to the rotor (e.g., for a given winding material), allowing for higher rotational speeds and, in some cases, reducing the need for bonded connections between rotor components. In some cases, retaining windings are made of composite materials, such as carbon fiber composites, or more specifically, unidirectional epoxy carbon composites, due to their high strength-to-weight ratio. Accordingly, the winding configuration of the retaining windings on the rotor can be optimized or selected to provide the necessary reinforcement required for a specific application while also minimizing weight.

[0074] For example, such as Figure 13 As shown, in some applications, the retaining winding 240 can be configured as a circumferential retaining strip that can wrap around part or all of the axial length of the rotor 104. Due to this circumferential configuration, the retaining winding 240 can apply compressive force in the radial direction to both the winding 214 and the rotor body 202 (e.g., at the pole cap 210). Accordingly, the retaining winding 240 can also counteract the centripetal force experienced by the rotor components during rotation. In other non-limiting examples, more than one retaining winding can be used, and they can be positioned at arbitrary locations along the axial length of the rotor 104.

[0075] In some examples, to allow the retaining winding 240 to apply force to the winding 214 more effectively, the rotor 104 may include a retainer 242 positioned between the retaining winding 240 and the winding 214 (see also). Figure 3 , 5 (and 6). More specifically, the retainer 242 may be positioned within the winding channel between each pair of teeth 208 and may span the inter-pole tip gap. Circumferential retaining windings may necessitate designs that increase the air gap between the rotor 104 and stator 102 to accommodate the thickness of the retaining winding. Thus, in some examples, to help reduce the air gap, the rotor 104 may define a channel 244 (e.g., a localized area or reduced perimeter of the rotor body 202), and the retaining winding 240 may be disposed within this channel 244. As a result, rotor laminations wound with the retaining winding 240 may have a smaller diameter to accommodate the presence of the retaining winding 240, while unwound rotor laminations may have a larger diameter. This combination can simultaneously achieve a smaller air gap and improve the electromagnetic performance of the motor 100.

[0076] In other examples, such as Figure 14 and Figure 15 As shown, the retaining winding 240 can be configured as an axial retaining strip. That is, the retaining winding 240 can be wound around two teeth and around each end of the rotor, such that the winding extends along the length axial direction of the teeth 208 (e.g., perpendicular to the circumferential direction). The axial portion of the retaining winding 240 can be received in and extend along the winding channel between the teeth 208. In this way, the overall diameter can be reduced, thereby minimizing the air gap between the rotor 104 and the stator 102. Accordingly, similar to... Figure 13 For circumferential winding, retainer 242 can be positioned between retainer winding 240 and winding 214 (see...). Figure 16 To facilitate the radial transmission of force to winding 214, in some examples, retainer 242 has a crown-shaped outer surface 246.

[0077] When using an axially wound configuration, the rotor may include multiple axially retained wound elements 240. For example... Figure 15 As best shown, rotor 104 includes six axially retained windings 240A-240F. The windings 240A-240F are arranged in a star pattern, wherein each tooth 208 is wound together with its immediate neighboring tooth. In other words, the retained winding 240 extends beyond the end of rotor 104 and crosses between two adjacent teeth along the winding channel. In other examples, the retained windings 240 may be arranged in other ways.

[0078] Accordingly, since the axial winding causes the retained winding 240 to extend around the end of the rotor 104, a cap 248 can be provided on the end of the rotor 104. In some cases, the cap 248 can be constructed as a molded or 3D-printed cap made of plastic, composite materials (e.g., glass fiber, carbon fiber, etc.), steel, aluminum, or other materials. In some cases, the cap 248 can be constructed as an end plate for bolting or clamping the rotor (e.g., applying axial compression to the rotor 104) and for rotational balancing of the rotor 104. The cap 248 can help guide, support, and secure the retained winding 240 between the winding channels. Additionally, the cap 248 can also help guide, support, and secure the winding 214 between the winding channels (e.g., see...). Figure 16 In some cases, cap 248 can also function as a retainer by ensuring that proper tension is maintained on rotor 104.

[0079] In some cases, the retaining winding can be pre-tensioned to apply a predetermined compressive force to the rotor (e.g., a rotor in a non-rotating state). For example, the retaining winding can be wound under tension to apply a radial compressive force to the rotor, thereby compressively preloading it so that the components remain in contact under rotational inertial loads, which represent "unloading" the preload. Specific pre-tension ranges can be between about 10% to about 50% of the ultimate strain of the retaining winding material, or between about 20% and about 30%. In this way, the retaining winding can maintain compression on the rotor components despite the centripetal force that acts during rotation to reduce the pre-tension load.

[0080] Furthermore, the compression applied to the rotor can reduce the stress on rotor components (e.g., pole caps) during operation, thereby allowing for higher maximum rotational speeds (e.g., achieving speeds two times or more higher than those of rotors not wound with pre-tensioned windings). For example, Figure 17 The stress present in the bonded pole cap during rotor rotation is shown. By applying preload with retained windings, the stress within the pole cap can be reduced, allowing for higher rotational speeds. See also... Figure 18 If the preload is high enough that bonding connections are not required at the pole cap, the stress within the pole cap can be further reduced, allowing for higher speeds. In each case, a specific preload can be selected such that the stress in the pole cap does not exceed the yield strength of the pole cap material.

[0081] In some cases, the preload of the retaining winding can be completed with lower tension to simplify the manufacturing process. That is, the total preload required to retain the copper winding, pole cap, and retainer can range from thousands to tens of thousands of Newtons, depending on the machine size and expected speed. Winding the entire winding at full preload tension can be difficult and requires larger and more robust machines. However, it is possible to perform the winding process, or at least partially winding, with lower tension. Specifically, uncured unidirectional fiber composites (i.e., the fibers forming the retaining winding) can be wound in small, multi-layered increments, reducing the required winding tension while retaining the total compressive strength of the winding. For example, a circumferential winding requiring a 4,000-pound preload can be wound in two 20-segment layers with a tension of only 100 pounds. This winding can even be done with small amounts of fiber at a time, or even fiber by fiber, reducing the required winding tension to a few Newtons.

[0082] The winding rotor can begin with very low tension; as the wound length increases, the friction generated throughout the previously wound length will support increasingly higher winding tensions until the target tension is reached. Similarly, at the end of the winding process, the tension can be gradually reduced. This reduces the need to secure the ends of the winding under high tension (e.g., using fasteners). The winding can then be cured to form a pre-tensioned, integral, unidirectional composite tape. In some cases, the ends of the winding can also be wound to reinforce the radial support of the end windings.

[0083] While the pretensioning of the retained winding allows composite-wound rotors to achieve significantly higher speeds than their equivalent unwound counterparts, the different materials in the retained winding and the rotor typically have different coefficients of thermal expansion. For example, the coefficient of thermal expansion of steel can be greater than that of the fiber-reinforced composite material (e.g., epoxy carbon) that makes up the retained winding. More specifically, the steel in the rotor can have a positive coefficient of thermal expansion, while the retained winding can have a negative coefficient. Therefore, when the temperature rises, such as during motor operation, the rotor may expand, while the retained winding may contract. This differential thermal expansion / contraction between the rotor steel and the retained winding can, in some cases, lead to the generation of additional stresses as the temperature rises.

[0084] To help account for the differential thermal expansion / contraction between the rotor steel and the retained winding, the rotor may also include a compliant member. The compliant member can be positioned between the rotor body and the retained winding and can be configured to deform flexibly to reduce stress caused by differential thermal expansion. Specifically, the compliant member allows the rotor body and the retained winding to change shape with temperature without substantially altering the overall outer diameter of the rotor. Therefore, the compliant member allows the rotor body to change shape with temperature because the steel expands while the belt (essentially) does not, allowing the outer diameter of the rotor body across the pole caps to increase while the total length of the belt remains substantially constant, thus avoiding increased stress in the belt. This provides more leeway for belt pretensioning, thinner belts, higher speeds, or some combination thereof. Furthermore, the substantially constant outer diameter of the rotor allows the retained windings to continue applying the required amount of inward radial force to the rotor (e.g., pole caps and windings) and mitigates the tendency for gaps to appear between different sections of the rotor body under rotational inertial loads. The ability of the compliant member to accommodate the different expansion and contraction of rotor components can be determined by the material properties or geometry of the compliant member.

[0085] In some respects, the compliant member can be configured to contract and / or expand during operation to maintain tension on the retained winding during operation. For example, during operation, heat and centripetal forces may cause the rotor to expand and the retained winding 240 to contract, which may result in increased tension, thereby increasing the force and stress on the rotor components. However, in other examples, considering that the rotor and the retained member may have different coefficients of thermal expansion, heat and centripetal forces may cause the retained winding 240 to expand. This may result in decreased tension, thereby reducing the force on the rotor components. To counteract this expansion and maintain a (minimum) predetermined tension on the retained winding 240, the compliant member 280 may also expand, such as Figure 5 and Figure 13 As shown. In this respect, the compliant member 280 can be constructed as an elastic member, which can be preloaded by the tension winding 240. As the centripetal force causes the tension winding 242 to expand, the compliant member 280 can expand due to the reduced load, thereby absorbing the expansion of the retained winding 240 and ensuring that proper tension is applied to the rotor. In some cases, the compliant member 280 may undergo thermal expansion due to temperature rise. This thermal expansion is sufficient to cause the compliant member 280 to expand, thereby absorbing the expansion of the retained winding 240 and ensuring that proper tension is applied to the rotor. Accordingly, although only a single retained winding is depicted, it is understood that multiple retained windings can be used.

[0086] In some cases, the compliant member can be positioned within the winding channel to retain the winding between the coil and the coil. For example, as... Figure 5 and Figure 13 As shown, the compliant member 280 can be positioned within the winding channel, between the retainer 240 and the winding 214. More specifically, the compliant member 280 can be positioned between the retainer 242 and the winding 214, such that the compressive force from the retainer 240 is more evenly distributed along the compliant member 280.

[0087] The compliant member and the retainer can together constitute the retention body. Alternatively, the compliant member and the retainer can form a single retention body. For example, as... Figure 3 As shown, the retainer body 282 is positioned between the retainer winding 240 and the winding 214. The retainer body 282 is specifically shaped to function as both the compliant member 280 and the retainer 242. Specifically, the arcuate outer surface increases the rigidity of the retainer body 282, making it function similarly to the retainer 242, while the substantially flat inner surface provides compliance, making it function similarly to the compliant member 280.

[0088] In some cases, the compliant component can also be configured to provide cooling for the rotor. For example, see... Figure 19In some cases, the compliant member 280 may cover the winding 214. In this way, the compliant member 280 may also serve as a cooling tank 284 to contain and control the flow of coolant around the winding 214. Accordingly, the end cap 248 may be used to form a tightly closed space or chamber around the end of the rotor winding, or to form multiple closed spaces around the end of a single coil, through which coolant (e.g., ATF oil) may be injected to absorb and dissipate waste heat from the winding.

[0089] Alternatively, the coolant can be forced downward along the rotor length axially between the winding and the rotor core within an insulating cooling tank formed by the compliant member 280. For this purpose, the use of an axial cooling tank is made possible by the removability of the spool winding and the pole caps, since it would otherwise be difficult to manufacture an axial cooling tank in situ on the rotor. Therefore, according to this disclosure, the cooling tank can be fixed around the spool winding before it is mounted onto the plurality of shanks.

[0090] Using a cooling canister can also allow for higher current densities, increasing by two times or more, resulting in higher power, torque, and efficiency. Accordingly, regardless of whether the rotor includes a cooling canister, it can be shaped to allow for higher winding packing densities. More specifically, it can be advantageous to shape the pole caps with inwardly sloping protruding tips. These protruding tips allow the pole caps to retain the rotor windings and the retainers used to hold the rotor windings in place, while reducing stress caused by the rotor windings and retainers.

[0091] Specifically, see Figure 20 The pole cap 210 typically includes a protruding tip 274 that extends circumferentially away from the shank 206. The tip 274 defines a radially inner surface 276 that engages with the winding 214. The inner surface 276 may be angled relative to the radial direction at an angle 278, which can be selected based on the cross-sectional shape of the conductor constituting the winding 214. In the case of round conductors, the angle 278 may be an acute angle relative to the radial direction, for example, between about 50 degrees and about 70 degrees, or more specifically, about 60 degrees relative to the radial direction. Besides allowing for denser windings, the angle 278 can also reduce the normal force applied to the pole cap 210 during rotation, thereby reducing stress in the material and allowing for higher rotational speeds.

[0092] As discussed above, retaining the winding can be used to hold rotor components together to allow the rotor to operate at higher speeds. Specifically, retaining the winding can counteract the centripetal forces experienced by the rotor components during rotation, thereby ensuring that the various internal components maintain contact under rotational inertial loads. Relatedly, caps (e.g., end caps) can be used to further enhance the structural integrity of the rotor by providing axial compression to the rotor relative to the rotor axis defined by the rotor shaft. Furthermore, balancing rings can be provided to cover the end caps, and the rotor shaft can define flanges to compress the balancing rings at both axial ends of the rotor, which in turn holds the rotor components together and further maintains contact under rotational inertial loads.

[0093] See now Figure 21 The diagram shows a cross-sectional view of a rotor 104, which may include rotor windings 214 that can be secured within a retainer 242. Furthermore, caps 248 may be configured for bolting or clamping end plates of the rotor 104 to apply axial compression to the rotor 104, as discussed above. Another rotor component, such as a balance ring, may be used to secure the caps to the axial ends of the rotor to help minimize rotational imbalance in the rotor. For example, as shown in a non-limiting example, caps 248 may be coupled to retainer 242. To help secure caps 248 to retainer 242, first balance rings 286 may be placed on each cap 248. That is, first balance rings 286 may sit above caps 248 to secure caps 248 and rotor windings 214 between the first balance rings 286 and retainer 242. In some cases, retainer 242 may be configured to prevent the first balance rings 286 from rotating relative to the rest of the rotor 104 during operation (e.g., ensuring common rotation of all rotor components).

[0094] Furthermore, in some examples, the second balancing ring 288 may at least partially sit on one or both of the first balancing rings 286 to secure the first balancing ring 286 between the cap(s) 248 and(s) the second balancing rings 288. Specifically, the second balancing ring 288 may be bent or folded over the first balancing ring 286 to secure the first balancing ring 286 to the rotor 104 (e.g., via a roll forming process). For example, the outer edge 290 of the second balancing ring 288 may be bent or folded over the radially inner lip 292 of the first balancing ring 286. In this way, the second balancing ring 288 can serve as a retaining structure, providing axial compression to the rotor 104 and securing the first balancing ring 286 to the rotor 104. In some examples, the second balancing ring 288 may define a diameter smaller than that of the first balancing ring 286, and the second balancing ring 288 may be arranged concentrically relative to the first balancing ring 286. Although only a single second balancing ring is shown in the non-limiting example, it will be understood that multiple second balancing rings may be used (e.g., second balancing rings positioned at either axial end of the rotor).

[0095] Therefore, according to aspects of this disclosure, the balance ring can be secured without the use of separate fasteners, whereas fasteners are typically used in conventional rotor structures. See also: [link to relevant documentation] Figure 21-23 The first balancing ring 286 and / or the second balancing ring 288 can be secured to the rotor 104 via the rotor shaft 106. More specifically, the rotor shaft 106 may include a flange 294 at each end. The flange 294 can be bent or folded onto the balancing rings 286, 288 to secure the balancing rings 286, 288 to the rotor 104 (e.g., via a roll forming process). For example, the flange 294 can be bent or folded onto the radially inner lip 292 of the first balancing ring 286, and / or the flange 294 can be bent or folded onto the base 296 of the second balancing ring 288 (i.e., the base 296 integral with the outer edge 290 and radially inward relative to the outer edge 290). In this way, the flange 294 can serve as a retaining structure to provide axial compression to the rotor 104. Specifically, flange 294 can provide axial compression to back iron 204, rotor winding 214, retainer 242, end cap 248, first balance ring 286, and / or second balance ring 288. Constructing rotor 104 in this way reduces rotor complexity while providing enhanced structural integrity. For example, balance rings 286, 288, and end cap 248 can individually or in combination provide mechanical support for rotor winding 214 at a range of rotor speeds.

[0096] As described above, the rotor can be used in conjunction with a cooling device. As used in the claims, the phrase "at least one of A, B, and C" means at least one of A, B, and / or C, or any one of A, B, or C, or a combination of A, B, and C. A, B, and C are elements in the list, and A, B, and C can be anything included in the specification.

[0097] The invention has been described with reference to one or more specific embodiments, and it should be understood that many equivalents, substitutions, variations and modifications may be made within the scope of the invention, in addition to those expressly stated.

[0098] Other examples

[0099] Example 1: A rotor for an electric motor includes: a rotor body defining a rotor axis and a plurality of teeth extending radially away from the rotor axis, the rotor body including: a back iron; a plurality of shanks extending radially away from the back iron, each of the plurality of shanks corresponding to one of the plurality of teeth; a plurality of pole caps, each of the plurality of pole caps being removably coupled to a corresponding one of the plurality of shanks; and a rotor winding wound around the plurality of teeth.

[0100] Example 2: The rotor according to Example 1, wherein a plurality of pole caps are made of a first material, and at least one back iron or a plurality of shanks are made of a second material different from the first material.

[0101] Example 3: The rotor according to Example 2, wherein the first material is electrical steel and the second material is carbon steel.

[0102] Example 4: The rotor according to Example 2 or 3, wherein the back iron is made of a second material and the plurality of shanks are made of a third material.

[0103] Example 5: The rotor according to Example 4, wherein the second material is a first electrical steel having a first grain orientation, and the third material is a second electrical steel having a second grain orientation.

[0104] Example 6: The rotor according to Example 5, wherein a first grain orientation is oriented in a circumferential direction relative to the rotor axis, and a second grain orientation is oriented in a radial direction relative to the rotor axis.

[0105] Example 7: The rotor according to Examples 1 to 6, wherein the rotor body comprises a stack of laminations formed by stacking a plurality of laminations along the rotor axis.

[0106] Example 8: The rotor according to Example 7, wherein each of the plurality of laminations is an integral lamination forming both a back iron and a plurality of shanks.

[0107] Example 9: The rotor according to Example 7 or 8, wherein the plurality of laminations include a plurality of back iron laminations and a plurality of shank laminations, the plurality of back iron laminations together forming a back iron, and the plurality of shank laminations together forming a plurality of shanks.

[0108] Example 10: The rotor according to Examples 7 to 9 further includes a first end cap and a second end cap disposed at opposite ends of the rotor body to provide clamping force on the plurality of laminations and retain the rotor windings on the rotor body.

[0109] Example 11: The rotor according to Example 10, wherein each of the first end cap and the second end cap is made of at least one of a polymeric material and a composite material.

[0110] Example 12: A rotor according to Examples 1 to 11, wherein a plurality of pole caps are retained on the rotor body by retaining windings.

[0111] Example 13: The rotor according to Examples 1 to 12, wherein each of the plurality of pole caps is connected to a corresponding one of the plurality of shanks by a keyway connection.

[0112] Example 14: The rotor according to Examples 1 to 13, wherein each of the plurality of pole caps is connected to a corresponding one of the plurality of shanks by fasteners.

[0113] Example 15: The rotor according to Examples 1 to 14, wherein each of the plurality of shanks is connected to the back iron by a keyway connection.

[0114] Example 16: The rotor according to Examples 1 to 15, wherein the back iron includes a plurality of back iron segments, each of the plurality of back iron segments being configured to be connected to a corresponding one of the plurality of shanks.

[0115] Example 17: An electric motor includes: a stator; and a rotor configured to rotate relative to the stator, the rotor including: a rotor body defining a plurality of teeth, a rotor winding wound around the plurality of teeth, a retaining winding wound around the rotor body, the retaining winding wound being configured to apply a compressive force to retain the rotor winding on the rotor body, and a compliant member configured to maintain the retaining winding wound within a predetermined tension range.

[0116] Example 18: The motor according to Example 17, wherein the predetermined tension range is between 10% and 50% of the ultimate strain of the retaining winding.

[0117] Example 19: The motor according to Example 18, wherein the retaining winding is pre-tensioned to about 30% of the ultimate strain of the retaining winding.

[0118] Example 20: The motor according to Examples 17 to 19, wherein the compliant member is positioned within a winding channel formed between two adjacent teeth of a plurality of teeth.

[0119] Example 21: The motor according to Examples 17 to 20, wherein the compliant member is configured as a cooling tank, which may be configured as a coil enclosing the rotor winding.

[0120] Example 22: The motor according to Examples 17 to 21, wherein the compliant member is radially positioned between the retaining winding and at least one of the rotor bodies and the rotor windings.

[0121] Example 23: The motor according to Examples 17 to 22, wherein the retaining winding is circumferentially wound around the rotor body.

[0122] Example 24: The motor according to Examples 17 to 23, wherein the retaining winding is axially wound around the rotor body, and the retaining winding extends between a first channel formed between a first pair of adjacent teeth of a plurality of teeth and a second channel formed between a second pair of adjacent teeth of a plurality of teeth.

[0123] Example 25: The motor according to Example 24, wherein the rotor includes a first end cap and a second end cap positioned at opposite ends of the rotor body, and wherein a retaining winding extends along each of the first and second end caps between a first channel and a second channel to apply axial compression to the rotor body.

[0124] Example 26: The motor according to Examples 17 to 25, wherein the compliant member is configured to compensate for thermal expansion between the rotor and the retained winding to maintain the retained winding within a predetermined tension range.

[0125] Example 27: The motor according to Examples 17 to 26, wherein the rotor further includes a retainer positioned between the retaining winding and the compliant member, the retainer being configured to maintain the retaining winding in a predetermined shape.

[0126] Example 28: The motor according to Example 27, wherein the retainer and the compliant member are integrally formed as a retaining body.

[0127] Example 29: An electric motor with reconfigurable poles, the motor comprising: a stator; and a rotor configured to rotate relative to the stator, the rotor comprising a plurality of rotor windings wound with respective plurality of teeth extending from a rotor core, the rotor core being made of a magnetizable material and configured to be selectively magnetized into a first pole configuration having a first number of poles and a second pole configuration having a second number of poles different from the first number of poles.

[0128] Example 30: The motor according to Example 29, wherein both the first number of poles and the second number of poles are divisible by the total number of teeth in the plurality of teeth.

[0129] Example 31: The motor according to Example 29 or 30, wherein at least one of the following is true: the plurality of teeth consists of four teeth, the first number of poles includes four poles, and the second number of poles includes two poles; the plurality of teeth consists of six teeth, the first number of poles includes six poles, and the second number of poles includes two poles; and the plurality of teeth consists of eight teeth, wherein the first number of poles and the second number of poles are selected from the group consisting of eight poles, four poles, and two poles.

[0130] Example 32: The motor according to Examples 29 to 31 further includes a controller configured to selectively magnetize the rotor core to switch between a first pole configuration and a second pole configuration.

[0131] Example 33: The motor according to Example 32, wherein the controller is configured to switch between a first pole configuration and a second pole configuration based on the motor's operating parameters.

[0132] Example 34: The motor according to Example 33, wherein the operating parameters include at least one of the motor's torque output or speed.

[0133] Example 35: The motor according to Examples 32 to 34, wherein the stator includes stator windings and the controller is configured to control the current flow in the stator windings, which induces a corresponding current in the rotor core to switch the rotor core between a first pole configuration and a second pole configuration.

[0134] Example 36: The motor according to Examples 29 to 35, wherein each of the plurality of teeth includes a pole cap made of electrical steel and the rotor core is made of carbon steel.

[0135] Example 37: A rotor assembly for an electric motor, the rotor comprising: a rotor shaft including a flange disposed at an end of the rotor shaft; a rotor body coupled to the rotor shaft; a rotor winding supported on the rotor body; and a balancing ring for retaining the rotor winding on the rotor body, the balancing ring defining an inner lip, the flange being bent on the inner lip to retain the rotor winding on the rotor shaft.

[0136] Example 38: The rotor assembly according to Example 37, wherein the flange provides axial compression to the balance ring, rotor winding and back iron relative to the rotor axis defined by the rotor shaft.

[0137] Example 39: The rotor assembly according to Example 37 further includes a retainer positioned between the rotor winding and the rotor body.

[0138] Example 40: The rotor assembly according to Example 39 further includes an end cap configured to enclose the rotor winding on the retainer, the end cap being positioned between the rotor winding and the balance ring.

[0139] Example 41: The rotor assembly according to Example 40 further includes an end cap configured to enclose the rotor winding on the retainer, the end cap being positioned between the rotor winding and the balance ring.

[0140] Example 42: The rotor assembly according to Example 41, wherein the second balancing ring retains the first balancing ring on the rotor shaft.

[0141] Example 43: The rotor assembly according to Example 42, wherein the second balancing ring defines an outer edge that bends over a second inner lip of the first balancing ring to retain the first balancing ring on the rotor shaft.

Claims

1. A rotor for an electric motor, comprising: A rotor body defining a rotor axis and a plurality of teeth extending radially away from the rotor axis, the rotor body comprising: Back iron; A plurality of shanks extending radially away from the back iron, each of the plurality of shanks corresponding to one of the plurality of teeth, and A plurality of pole caps, each of the plurality of pole caps being removably coupled to a corresponding one of the plurality of handles; and Rotor windings with the multiple teeth wound around them.

2. The rotor according to claim 1, characterized in that, The plurality of pole caps are made of a first material, and at least one of the back irons and the plurality of handles are made of a second material different from the first material.

3. The rotor according to claim 2, characterized in that, The first material is electrical steel, and the second material is carbon steel.

4. The rotor according to claim 2, characterized in that, The back iron is made of the second material, and the plurality of handles are made of the third material.

5. The rotor according to claim 4, characterized in that, The second material is a first electrical steel with a first grain orientation, and the third material is a second electrical steel with a second grain orientation.

6. The rotor according to claim 5, characterized in that, The first grain orientation is oriented circumferentially relative to the rotor axis, and the second grain orientation is oriented radially relative to the rotor axis.

7. The rotor according to claim 1, characterized in that, The rotor body comprises a stack of multiple laminations stacked along the rotor axis.

8. The rotor according to claim 7, characterized in that, Each of the plurality of stacked pieces is an integral stacked piece, forming both the back iron and the plurality of handles.

9. The rotor according to claim 7, characterized in that, The plurality of stacked plates includes a plurality of back iron stacked plates and a plurality of handle stacked plates, the plurality of back iron stacked plates together forming the back iron, and the plurality of handle stacked plates together forming the plurality of handles.

10. The rotor according to claim 9, characterized in that, It also includes a first end cap and a second end cap disposed at opposite ends of the rotor body to provide clamping force on the plurality of laminations and retain the rotor windings on the rotor body.

11. The rotor according to claim 10, characterized in that, Each of the first end cap and the second end cap is made of at least one of polymeric materials and composite materials.

12. The rotor according to claim 1, characterized in that, The multiple pole caps are retained on the rotor body by retaining the winding.

13. The rotor according to claim 1, characterized in that, Each of the plurality of pole caps is connected to a corresponding one of the plurality of handles via a keyed connection.

14. The rotor according to claim 1, characterized in that, Each of the plurality of pole caps is connected to a corresponding one of the plurality of handles by a fastener.

15. The rotor according to claim 1, characterized in that, Each of the plurality of handles is connected to the back iron via a keyway.

16. The rotor according to claim 1, characterized in that, The back iron includes a plurality of back iron segments, each of which is configured to be connected to a corresponding one of the plurality of handles.

17. An electric motor, comprising: stator; as well as A rotor configured to rotate relative to the stator, the rotor comprising: A rotor body with multiple teeth; Rotor windings with the multiple teeth wound around them. A retaining winding element wound around the rotor body, the retaining winding element being configured to apply a compressive force to retain the rotor winding on the rotor body, and A compliant member configured to maintain the retained winding within a predetermined tension range.

18. The motor according to claim 17, characterized in that, The predetermined tension range is between 10% and 50% of the ultimate strain of the retained winding.

19. The motor according to claim 18, characterized in that, Pre-tension the retained winding to approximately 30% of its ultimate strain.

20. The motor according to claim 17, characterized in that, The compliant member is positioned within the winding channel formed between two adjacent teeth of the plurality of teeth.

21. The motor according to claim 20, characterized in that, The compliant member is configured as a cooling tank, which can be configured as a coil surrounding the rotor winding.

22. The motor according to claim 17, characterized in that, The compliant member is radially positioned between the retained winding and at least one of the rotor bodies and the rotor windings.

23. The motor according to claim 17, characterized in that, The retained winding is wound circumferentially around the rotor body.

24. The motor according to claim 17, characterized in that, The retaining winding is axially wound around the rotor body, and the retaining winding extends between a first channel formed between a first pair of adjacent teeth of the plurality of teeth and a second channel formed between a second pair of adjacent teeth of the plurality of teeth.

25. The motor according to claim 24, characterized in that, The rotor includes a first end cap and a second end cap positioned at opposite ends of the rotor body, and The retained winding extends along each of the first and second end caps between the first and second channels to apply axial compression to the rotor body.

26. The motor according to claim 17, characterized in that, The compliant member is configured to compensate for thermal expansion between the rotor and the retained winding to maintain the retained winding within the predetermined tension range.

27. The motor according to claim 26, characterized in that, The rotor also includes a retainer positioned between the retaining winding and the compliant member, the retainer being configured to maintain the retaining winding in a predetermined shape.

28. The motor according to claim 27, characterized in that, The retainer and the compliant member are integrally formed into a retaining body.

29. A motor having reconfigurable poles, the motor comprising: stator; as well as A rotor configured to rotate relative to the stator, the rotor comprising a plurality of rotor windings wound with corresponding plurality of teeth extending from a rotor core, the rotor core being made of a magnetizable material and configured to be selectively magnetized into a first pole configuration having a first number of poles and a second pole configuration having a second number of poles different from the first number of poles.

30. The motor according to claim 29, characterized in that, Both the first pole number and the second pole number are divisible by the total number of teeth in the plurality of teeth.

31. The motor according to claim 30, characterized in that, At least one of the following: The plurality of teeth are composed of four teeth, the first number of poles includes four poles, and the second number of poles includes two poles; The plurality of teeth consists of six teeth, the first number of poles includes six poles, and the second number of poles includes two poles; and The plurality of teeth consists of eight teeth, and the first number of poles and the second number of poles are selected from the following groups: eight poles, four poles and two poles.

32. The motor according to claim 29, characterized in that, It also includes a controller configured to selectively magnetize the rotor core to switch between the first pole configuration and the second pole configuration.

33. The motor according to claim 32, characterized in that, The controller is configured to switch between the first pole configuration and the second pole configuration based on the operating parameters of the motor.

34. The motor according to claim 33, characterized in that, The operating parameters include at least one of the motor's torque output or speed.

35. The motor according to claim 32, characterized in that, The stator includes stator windings, and the controller is configured to control the current flow in the stator windings, which induces a corresponding current in the rotor core to switch the rotor core between a first pole configuration and a second pole configuration.

36. The motor according to claim 29, characterized in that, Each of the plurality of teeth includes a pole cap made of electrical steel, and the rotor core is made of carbon steel.

37. A rotor assembly for an electric motor, comprising: A rotor shaft including a flange, the flange being disposed at the end of the rotor shaft; The rotor body connected to the rotor shaft; Rotor windings supported on the rotor body; as well as A balance ring that retains the rotor winding on the rotor body defines an inner lip, and a flange is bent over the inner lip to retain the rotor winding on the rotor shaft.

38. The rotor assembly according to claim 37, characterized in that, The flange provides axial compression relative to the rotor axis defined by the rotor shaft to the balance ring, the rotor winding, and the rotor body.

39. The rotor assembly according to claim 37, characterized in that, It also includes a retainer positioned between the rotor winding and the rotor body.

40. The rotor assembly according to claim 39, characterized in that, It also includes an end cap configured to enclose the rotor winding on the retainer, the end cap being positioned between the rotor winding and the balance ring.

41. The rotor assembly according to claim 40, characterized in that, The balancing ring includes a first balancing ring and a second balancing ring, the second balancing ring being concentrically positioned relative to the first balancing ring, and the diameter defined by the second balancing ring being smaller than the diameter of the first balancing ring.

42. The rotor assembly according to claim 41, characterized in that, The second balancing ring retains the first balancing ring on the rotor shaft.

43. The rotor assembly according to claim 42, characterized in that, The second balancing ring defines an outer edge that bends over a second inner lip of the first balancing ring to retain the first balancing ring on the rotor shaft.

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