Electrical Machines and Systems

Abstract

To provide a motor with reduced loss and improved torque.SOLUTION: In an electric machine which is an outer runner motor, a rotor is rotatably attached to a shaft 101. A stator assembly 200 has a stator core 201 made of non-ferromagnetic material. Axial flux stator yokes 202A and 202B have an inner wall that is rigidly attached to an outer surface of a first end wall of the stator core, or a radial flux stator yoke 203 has a continuous inner wall that is rigidly attached to a continuous outer wall of the stator core. The axial flux stator yoke or the radial flux stator yoke includes a laminated sheet and a slot. Winding 204 may be positioned in the slot of the axial flux stator yoke or the radial flux stator yoke. The stator core and the shaft include spline coupling that is selectively coupled to fit the stator core to the shaft.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present disclosure relates to motors, and more particularly to motor designs including outer runner electric motor designs and combined axial and radial flux motor designs, in which the stator assembly has a stator core using a non-ferromagnetic material secured to a shaft via a splined structure, and the stator assembly can utilize electrical laminations, thereby reducing losses and improving torque. [Background technology]

[0002] background Conventional electric motors are one of the most important energy conversion systems used in industry today. A conventional electric motor is an electric machine that converts electrical energy into mechanical energy. Most conventional electric motors work through the interaction of the motor's magnetic field with the current in the windings to generate force as a shaft rotates. For example, over 99% of the total electricity on earth is generated from generators, and roughly two-thirds of that energy ends up powering conventional electric motors. For example, the majority of electric machines use a radial flux motor design configuration due to its simplicity, but if torque density is the most important motor design requirement, then the type of motor configuration used is an axial flux motor.

[0003] As a general rule of thumb, most electric motors need to be paired with a transmission (such as a gearbox) to reduce speed when driving a load in various applications. This is due to two main reasons: (a) electric machines are typically most efficient at their rated speed, which is usually much higher than the required speed of the load, and (b) the direct torque output of an electric machine is usually insufficient for the application, and a transmission is required to boost the torque.

[0004] However, gearboxes typically have nonlinear dynamics such as backlash hysteresis and nonlinear Coulomb friction, which degrade the dynamic performance of the motor and are undesirable for high-precision applications. Therefore, in a variety of other application areas such as machine-room-less elevators, robotic manipulators, high-precision rotary stages, and in-wheel drives for electric vehicles, it may be beneficial to eliminate the transmission and directly drive the load with the motor.

[0005] For example, traditional axial flux permanent magnet motor designs are utilized to achieve high torque density targeted for direct drive motor applications such as those mentioned above. Such designs aid in reducing the axial length of the motor without losing torque capability. Some efforts to improve upon traditional direct drive motors have been directed towards surface mounted permanent magnet (PM) motors because these types of PM motors can have shear stress generation capabilities, among other motor principles.

[0006] All electric machines, including PM motors, can be classified according to their magnetic flux direction into axial and radial flux machines. Most electric machines use radial flux due to its simplicity. In radial flux machines, the magnetic field, i.e., the magnetic flux in the air gap between the rotor and stator, travels radially relative to the direction of the rotor. In axial flux machines, the magnetic field, i.e., the magnetic flux in the air gap between the rotor and stator, travels along the rotor shaft axis. However, in both types of machine designs, only a portion of the surface area along the stator is utilized as the air gap for generating torque.

[0007] One of the important conventional methods to try to improve the torque of a motor is by increasing the air gap surface area on the surface of the rotor. The air gap is the distance between the rotor and the stator. When additional torque generation is required, one effective conventional method to increase the torque of a motor is to use a combination of axial and radial flux for torque generation. In these cases, the air gap is configured in both axial and radial directions, and the magnetic flux in the stator is three-dimensional.

[0008] Permanent magnet synchronous motors, like other rotating electric motors, consist of a rotor and a stator. The stator is the stationary part and the rotor is the rotating part. Typically, the rotor is located inside the stator of the motor. There are also motor designs where the rotor is located outside the stator, i.e., using an inverted rotor or external rotor, which are called outer runner motors. Typically, in these types of outer runner motors, the rotor is made of permanent magnets made of a material with high coercivity for the permanent magnets. The stator consists of an outer frame and a core with windings, which are the most common designs using two-phase and three-phase windings. The working principle of a synchronous motor is based on the interaction of the rotating magnetic field of the stator with the constant magnetic field of the rotor. The magnetic field of the rotor interacts with the synchronous alternating current of the stator windings according to Ampere's law, generating torque that causes the rotor to rotate. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, there is a need for new motor design configurations, including combined axial and radial flux motor designs and outer runner motor designs, to improve torque generation and reduce losses in motors, including direct drive motor applications without the need for a gearbox, and to enable the use of electrical laminations. [Means for solving the problem]

[0010] overview The present disclosure relates to motors, and more particularly to motor designs including outer runner electric motor designs and combined axial and radial flux motor designs, in which the stator assembly has a stator core using a non-ferromagnetic material secured to a shaft via a splined structure, and the stator assembly can utilize electrical laminations, thereby reducing losses and improving torque.

[0011] Some embodiments include new motor designs that incorporate a splined structure that attaches the stator assembly to the stationary rotor shaft and replaces the traditional soft magnetic composite (SMC) or ferrite material in the center of the stator core with a non-ferromagnetic material, i.e., plastic or fiberglass, for motor types including combination axial and radial flux motors and outrunner motors.

[0012] For example, an embodiment may be configured to include an axial-flux and radial-flux motor having a rotor rotatably mounted about a machine axis, the rotor rotatably attached to a stationary shaft. The stator assembly may be configured to include some non-ferromagnetic material in the stator core and a radial-flux stator yoke having a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The first axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core, and the second axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a second end wall of the stator core. The radial-flux stator yoke and the first and second axial-flux stator yokes each include lamination sheets and slots. Also, windings may be positioned in the slots of the radial-flux stator yoke and the first and second axial-flux stator yokes. The stator core and shaft include splined engagement features adapted to selectively engage and mate the shaft to the stator assembly.

[0013] Another embodiment may include an outer runner motor having a rotor rotatably mounted about a machine axis, the rotor rotatably attached to the shaft. The stator assembly has a stator core using a non-ferromagnetic material. The axial flux yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core, or the radial flux yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The axial flux yoke and the radial flux yoke each include lamination sheets and slots. Windings may be positioned in the slots of the axial flux stator yoke or the radial flux stator yoke. The stator core and the shaft include splined coupling features adapted to selectively couple and mate the stator core to the shaft.

[0014] Splined structure It is contemplated for both of the above embodiments that the splined coupling feature includes a stator core configured with an external spline structure having teeth on the inner surface of the inner wall of the stator core that engages with a shaft that includes a corresponding internal spline structure having grooves on the outer surface of the shaft, and the stator core is mounted on the same shaft about which the rotor rotates, thereby allowing torque action to be transferred to generate torque forces.

[0015] Incorporating the splined structure into the stator core and stationary rotor shaft requires complex analysis to match each structural aspect of the splined structure with other motor elements of the motor so that all aspects of the motor are configured to achieve the desired operational performance. For example, each structural aspect of the splined structure includes associated characteristics that must be both evaluated and matched with other motor elements and their associated characteristics in order for the motor to operate as desired. Some of the structural aspects of the splined structure and their associated characteristics may include the following:

[0016] (1) Determine the size (side) of each toothFor example, some structural aspects that must be determined are tooth height, tooth width, and tooth depth. These structural aspects of the teeth must be designed according to the intended and designed operational performance of the motor. For example, if the tooth height is too long and does not match the estimated torque output for the other components of the motor, the tooth may break or the operational life of the tooth may be shortened if the intended and designed torque output is too large for that particular tooth height to withstand. Therefore, the characteristics of that particular tooth height are such that the tooth may fail or the operational life of the tooth may be shortened, resulting in the motor failing in either scenario. In other words, for the motor to operate as intended, it is necessary to identify and design the structural aspects of each particular tooth in terms of the intended and designed operational performance.

[0017] (2) Determine the number of teeth in the spline-like structure For example, the number of teeth may be determined by the amount of current the motor can generate, so if there are too many or too few teeth and not enough current is generated, the amount of torque output will be reduced and the intended motor design operating performance will not be achieved.

[0018] (3) Determine the tooth angles and the angular spacing or intervals between the teeth The tooth angle can be 360 ​​degrees divided by the number of teeth. The angular space or spacing between the teeth should be equal to each other.

[0019] (4) Determine the thermal coefficients for each tooth along with the thermal coefficients for all teeth of the spline-like structure. For example, all structural aspects of the teeth must be evaluated in terms of thermal coefficients to ensure that the motor can achieve its intended and designed operational performance. If the thermal coefficients of the specific structural aspects making up a particular tooth configuration are too low, then that particular tooth configuration characteristic will ultimately fail or have a reduced operational life due to exposure to a higher amount of heat than its rated thermal coefficient, among other reasons, such as coolant flow rate and temperature.

[0020] (5) Identifying the amount of torque for each tooth and / or associated teeth of the spline-like structureFor example, the motor design in terms of knowing the estimated amount of intended torque generation needs to be considered when constructing the teeth of a spline structure so that the teeth can be designed to withstand the estimated intended torque output so that the teeth do not break / fail or have a shortened operational life.

[0021] In order for a new motor design to operate as intended, the above structural aspects of the splined structure, along with the other motor elements of the motor (see next section below), need to be specifically designed according to the intended and designed operational performance for the motor to operate as intended.

[0022] Non-ferromagnetic material stator core The discovery of replacing the center of the stator core with a new material was realized through experimentation. For example, it was realized through testing that some of the SMC material of the conventional stator core was not utilized by the motor in terms of the motor's operational performance, among other aspects. It was realized that by replacing the SMC material of the conventional stator core with a non-ferromagnetic material, the total torque output of the motor could be increased for these types of motors, i.e., combination axial and radial flux motors and outrunner motors, compared to the total torque output of the motor to conventional motor types having stator cores using SMC material for the same motor size. This realization goes against all the conventional designs and conventional thinking of conventional designers of these types of motors, since these conventional combination axial and radial flux motors and outrunner designs are specifically designed to achieve higher torque density than other types of conventional motor designs. For example, conventional combination axial and radial flux motor designs have air gaps configured in both axial and radial directions, and the magnetic flux in the stator is three-dimensional. Since eddy currents are generated in all directions, conventional stator cores made of SMC materials were used to obtain low bulk electrical conductivity. However, it was later discovered that there were some negative effects of conventional stator cores made of SMC materials for these types of conventional motor designs, and as a result, these types of motor designs could not utilize conventional electrical laminations. Another negative aspect of these types of conventional motor designs is that the use of solid rotors results in low specific torque due to their structural configuration with a separate stator surrounding the rotor.

[0023] It was later discovered that by replacing the SMC material of the conventional stators for these types of motors with non-ferromagnetic materials such as plastic or fiberglass, conventional electrical laminations could be utilized in the manufacture of the stators. This discovery led to the development of a new motor design with separate axial and radial flux stators made of conventional electrical laminations that could later be assembled together. In this unique stator design with the center of the stator core using non-ferromagnetic material, the manufacturing cost of the stator core was reduced by using conventional electrical laminations. It was also realized that the use of conventional electrical laminations allowed for high torque output by having high material permeability, further reducing the amount of hysteresis loss of the motor. Therefore, some other aspects learned from the experiment are that this novel stator design also allowed for a higher level of specific torque output of the motor. Since the stator core contains non-ferromagnetic material, the overall weight of the stator assembly was reduced, improving the torque-to-mass ratio of the motor. Some other embodiments using this innovative stator core non-ferromagnetic material are configured to include one or a combination of features, such as an outrunner motor configuration, toroidal windings for the stator, or both.

[0024] Similar to the aspect of incorporating splined structures into some new motor designs, the replacement of SMC materials of conventional stator cores with non-ferromagnetic materials also required complex analysis of matching the stator cores using non-ferromagnetic materials with other motor elements of the motor to be able to achieve the desired operational performance. For example, in the development of the new motor designs of the present disclosure, the new stator core materials needed to be matched with all other motor elements and their associated characteristics, i.e., including the splined structures. Some of the aspects of the new stator cores and their associated characteristics may include the following:

[0025] (1) The number of slots is ?Based on experiments, the number of slots should be the same as the number of stator slots (for some motor designs, the number of slots is 24).

[0026] (2) The angular spacing of each slot is ?We learned from experimentation that each slot can take a different angular spacing and the angular spacing or spacing of each slot can be 360 ​​degrees divided by the number of slots, which calculates to 15 degrees. Each slot can take the same angular spacing.

[0027] (3) What size slot should the slot be in terms of height, width, and depth to produce the intended amount of torque? i.e., will more current result in more torque? For example, the height of the slot is equal to the length of the stator minus twice the thickness of the axial flux stator. The width of the slot is the same as the width of the radial flux stator slot and the height is 1.5 times the height of the radial flux stator slot. Increasing the current increases the total torque generated for the motor.

[0028] (4) The thermal coefficient is For example, too many slots may result in too much heat being generated, eventually resulting in the motor overheating. Therefore, the thermal coefficient of the selected stator core material should be as high as possible to cool or dissipate heat as much as possible. Then, the determined thermal coefficient can be combined with the associated cooling structure to avoid the motor overheating.

[0029] (5) The intended amount of torque is For example, if the slot depth is too shallow, the splined teeth cannot withstand the torque generated, which may result in the teeth being damaged. Based on experiments, the torque may be in the range of 150-250Nm, which is within the torque range in which the width of the splined teeth has sufficient strength against the torque and the splined teeth will not be damaged.

[0030] (6) What is the number of turns?For example, if the number of windings is not enough, at least one resulting effect is a decrease in motor performance, i.e., loss of the intended torque. Essentially, at least one effect is that the motor may not be powerful enough to initiate a motor, a magnetic field, or a relative motion opposite to the polarity of the input voltage to either the rotor or stator windings, but not both. Another example is what to do if there are too many windings. The number of turns may be determined, as a non-limiting example, by the number of the first primary winding compared to the second winding, which may be determined by the number of the third winding, all based on a formula for the voltage of the primary winding considering the secondary winding, etc. Thus, the determination of the number of windings depends on other factors of the particular motor type and configuration. According to at least one embodiment of the present disclosure, the number of windings is the same as the number of stator slots, and if there are not enough windings, less than the intended torque is produced. If there are too many windings, there is no place to place the windings inside the intended new motor design.

[0031] (7) What are the types of materials for the stator yoke? Some embodiments of the present disclosure have a stator core that uses a non-magnetic core, and the list of materials may include, as non-limiting examples, solid non-magnetic steel, resin, air, ceramics, titanium, fiberglass, carbon fiber, somaloy 1000 3P, somaly 130i 5P. The list of yoke materials other than laminated sheets may be solid materials or at least one power material that is compounded into or combines axial and radial flux yokes.

[0032] In order for the new motor design to operate as intended, the above structural aspects of the new stator core using non-ferromagnetic materials, along with the other motor elements of the motor, must be individually designed according to their intended and designed operational performance to achieve the operational performance levels for which the motor was designed.

[0033] Advantages and practical applications of spline-like structures. Once the complex analysis of matching the new stator core materials with the splined structures was completed, other discoveries and understandings were obtained as a result of several test experiments that these new motor designs underwent. For example, it was later discovered that the stator assemblies having the splined structures provided an increased level of resistance to stator stresses, resulting in performance characteristics of increased fatigue life and increased wear and tear resistance in similar tests, as compared to conventional motors of the same size and type that used stator assemblies that were pressed or glued onto the rotor shaft.

[0034] Experiments have shown that the tolerance levels increase when the motor reaches the system's design limit or capacity, including: (1) an increased level of drive strength fluctuations, believed to be due to the splined structure attached to the rotor shaft, which allows the motor to produce more total torque; and (2) an increased rotational transmission concentration, believed to be due to the splined structure attached to the rotor shaft, which increases the thrust producing area of ​​the motor on the rotor, and therefore the torque density of the motor.

[0035] These performance features and results are important to the motor industry for several reasons, because the disclosed embodiments provide increased wear and tear resistance, which translates into longer motor life, which is especially important in light of the motor industry making huge investments in condition monitoring of electric machines and seeking new diagnostic alternatives in fault detection to reduce operational costs, increase reliable motor operation, and improve service to customers.

[0036] Advantages and Practical Applications of Non-Ferromagnetic Stator Cores During these test experiments with the new motor design having a non-ferromagnetic material stator core, other discoveries and realizations were identified compared to conventional motors of the same size and type. For example, some advantages that were later identified were an increased torque generating area on the rotor's surface (i.e., the surface area between the rotor and the stator that can generate torque) compared to the torque generating area on the rotor's surface of a combination conventional axial-flux and radial-flux motor of the same size. At least one practical application of this advantage over conventional motors of the same size and type could be a surface mounted / interior permanent magnet motor.

[0037] A further realization is that the torque-to-mass ratio of the motor has improved compared to a similar conventional motor design of the same size because the overall weight of the motor has effectively been reduced. This is because non-ferromagnetic materials are much less dense than ferromagnetic materials, and by replacing the same volume of ferromagnetic material with the lighter non-ferromagnetic material, the overall mass of the motor has been reduced. At least one practical application of this advantage over conventional motors of the same size and type could be a squirrel cage / wound rotor type induction motor.

[0038] A further understanding is that the generation of nearly constant shear stress in the air gap increases the torque producing area without increasing the total cubic area / size of the motor i.e. the total volume of the motor, effectively improving the torque density of the motor compared to the torque producing area of ​​the total volume of a conventional motor of the same size and type of the same. Some of the practical applications of the new motor design over a conventional motor of the same size and type could be surface mount / interior permanent magnet motors.

[0039] A further discovery of some advantages of the toroidal winding feature specific to the windings wound on the core forming a toroidal stator assembly is that the copper losses of the motor are reduced as a result of the reduced length of the end turns, which helps to improve the overall efficiency of the motor, at least as compared to a conventional motor of the same size and of a similar type. Another aspect that has been identified is the increased flexibility in the design of the motor to optimize the torque density and / or specific torque amount, as compared to the flexible design of the conventional motor for a conventional motor of the same size using a core having a soft magnetic composite (SMC) or ferrite material. As stated above, all of the above advantages are based on comparing each of the above advantages to a similar conventional motor of the same size or to a similar type of conventional motor associated with each of the above advantages.

[0040] According to an embodiment of the disclosure, an electric machine is provided that is an axial-flux and radial-flux motor, the electric machine including a rotor rotatably mounted about a machine axis, the rotor rotatably attached to a shaft. The stator assembly has a stator core using a non-ferromagnetic material. The radial-flux stator yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The first axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core. The second axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a second end wall of the stator core. The radial-flux stator yoke and the first and second axial-flux stator yokes each include lamination sheets and slots. Windings are positioned in the slots of the radial-flux stator yoke and the first and second axial-flux stator yokes. The stator core and the shaft include splined coupling features adapted to selectively couple and mate the stator core to the shaft.

[0041] According to another embodiment of the present disclosure, an electric machine is provided that is an outer runner motor and has a rotor rotatably mounted about a machine axis, the rotor rotatably attached to the shaft. The stator assembly has a stator core using a non-ferromagnetic material. The axial flux yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core, or the radial flux yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The axial flux yoke or the radial flux yoke each includes laminated sheets and slots. Windings may be positioned in the slots of the axial flux stator yoke or the radial flux stator yoke. The stator core and the shaft include splined coupling features adapted to selectively couple and mate the stator core to the shaft.

[0042] Another embodiment of the present disclosure is a system including a transceiver that receives signals from a sensor associated with an axial-flux and radial-flux (AFARF) motor. A digital controller is configured to receive the signals and generate control signals that specify values ​​of one or a combination of polyphase voltages and currents of the AFARF motor to track a reference trajectory of the torque of the AFARF motor. The AFARF motor has a load that is positioned by the AFARF motor and controllable by the digital controller. The AFARF motor includes a rotor rotatably mounted about a machine axis, the rotor being rotatably attached to the shaft. The stator assembly has a stator core using a non-ferromagnetic material. The radial-flux stator yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The first axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core. The second axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a second end wall of the stator core. The radial flux stator yoke and the first and second axial flux stator yokes each include lamination sheets and slots. Windings are positioned within the slots of the radial flux stator yoke and the first and second axial flux stator yokes. The stator core and shaft include splined coupling features adapted to selectively couple to mate the shaft to the stator assembly.

[0043] The presently disclosed embodiments will be further described with reference to the accompanying drawings, which are not necessarily to scale, emphasis instead being placed generally on illustrating the principles of the presently disclosed embodiments. [Brief description of the drawings]

[0044] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1A] FIG. 1 is a schematic diagram illustrating a cross-sectional view of a motor according to an embodiment of the present disclosure. [Figure 1B] 4 is a schematic diagram illustrating an external spline structure of a stator core engaged with a corresponding internal spline structure according to some embodiments of the present disclosure. [Figure 2A] 1A-1C are schematic diagrams illustrating a motor stator assembly, including an isometric view of the motor stator assembly, according to some embodiments of the present disclosure. [Figure 2B] FIG. 2B is a schematic diagram illustrating the motor stator assembly of FIG. 2A including an exploded view of the motor stator assembly according to some embodiments of the present disclosure. [Figure 2C] 1 is a schematic diagram illustrating an external spline structure of a stator core having teeth on an inner surface of the stator core that engages with a corresponding internal spline structure having grooves on an outer surface of a shaft, according to some embodiments of the present disclosure. [Diagram 3] FIG. 1 is a schematic diagram illustrating an axial flux rotor assembly according to some embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram illustrating a radial flux rotor assembly according to some embodiments of the present disclosure. [Diagram 5] FIG. 2 is a schematic diagram illustrating a thermal connection between a motor stator assembly and a hollow shaft for cooling according to some embodiments of the present disclosure. [Figure 6] FIG. 1 is a block diagram illustrating a motor drive and control system according to some embodiments of the present disclosure. [Figure 7] FIG. 1 is a schematic diagram illustrating some components for a processor in communication with a controller system of a machine including an induction motor, according to some embodiments of the present disclosure. [Figure 8] FIG. 1 is a schematic diagram illustrating a centralized controller system that can be used to implement some systems and methods according to some embodiments of the present disclosure. [Figure 9A] FIG. 1 is a schematic diagram of an outer runner motor, showing a Type I motor, according to some embodiments of the present disclosure. [Figure 9B]1 is a schematic diagram of an outer runner motor, showing a Type II motor, in accordance with some embodiments of the present disclosure. While the above drawings show embodiments disclosed herein, other embodiments are contemplated as described herein. This disclosure shows illustrative embodiments by way of representation and not by way of limitation. Those skilled in the art will be able to envision numerous other modifications and embodiments that fall within the scope and spirit of the principles of the embodiments disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Detailed Description The present disclosure relates generally to motors, and more specifically to a motor configuration using a combination axial and radial flux that reduces losses and improves torque by using a stator core made of separate electrical laminations for the axial and radial fluxes.

[0046] 1A is a schematic diagram showing a cross-sectional view of a motor according to an embodiment of the present disclosure. The motor design of the present disclosure includes a combined axial and radial flux design for torque generation, which is applicable to direct drive applications.

[0047] 1B is a schematic diagram illustrating an external spline structure of a stator core 201 engaged with a corresponding internal spline structure, according to some embodiments of the present disclosure. For example, FIG. 1B illustrates that the bottom of the stator toroidal windings can pass through slots in the non-magnetic stator core 201.

[0048] 1A and 1B, the shaft 101 is the stationary motor shaft 101, and the line 100 in FIG. 1A is the axis of rotation of the rotor. A stator assembly 200 (see FIG. 2A and 2B for more details) is at the center of the whole machine, and the stator assembly 200 is fixed to the shaft 101. The stationary motor shaft 101 may be a hollow stationary motor shaft (see 599 in FIG. 5). The stationary motor shaft 101 may have an inner surface in the stationary shaft 101 that can be used as a cooling passage, through which a coolant can flow to dissipate the heat generated by the motor. Each stator assembly 200 comprises at least one stationary core 201 made of a non-ferromagnetic material, two axial-flux stator yokes 202A, 202B, and one radial-flux stator yoke. 203 and a series of stator windings 204.

[0049] Two axial flux rotor assemblies 300 and one radial flux rotor assembly 400 are configured to surround the stator assembly 200 and are free to rotate around the rotation axis 100. Here, each axial flux rotor assembly 300 is composed of one axial flux rotor housing 301, one axial flux rotor back-iron 302, and one axial flux permanent magnet (PM) array 303. The radial flux rotor assembly 400 is composed of one radial flux rotor housing 401, one radial flux rotor back-iron 402, and one radial flux PM array 403. The two rotor assemblies 300 and 400 are rigidly connected via threaded fasteners 105 and supported by bearings 104. The axial position of the bearings 104 is determined by a retaining ring 103.

[0050] FIG. 2A is a schematic diagram illustrating a motor stator assembly, including an isometric view of the motor stator assembly, according to some embodiments of the present disclosure.

[0051] FIG. 2B is a schematic diagram illustrating the motor stator assembly of FIG. 2A including an exploded view of the motor stator assembly according to some embodiments of the present disclosure.

[0052] 2A and 2B, the fixed core or at least one core 201 is made of a low-conductivity non-ferromagnetic material, for example, fiberglass. The core has slots on the inner diameter surface. One radial-flux stator yoke 203 and two axial-flux stator yokes 202a and 202b are rigidly attached to the fixed core 201 via structural adhesive. The axial-flux stator yoke 202 is made of a spiral electric lamination, and the lamination direction is radial. The axial-flux stator yoke 202 can be made by making a disk-shaped spiral, and then the slots are cut by electrical discharge machining (EDM). One radial-flux stator yoke 203 is made of an electric lamination stack, and the lamination direction is axial. Finally, the stator winding 204 is wound in the slots to surround the assembled stator yoke (including 201, 202, and 203). The stator winding 204 is made of multiple loops of magnetic copper wire, with three phases and a pole pair number Ps. Finally, the stator assembly 200 is mounted on the shaft 101 and rigidly connected through splines, and the teeth on the inner surface of 201 engage with the slots on the surface of the shaft 101. Thus, the stator assembly 200 can be fixed to the shaft and can transmit a large torque.

[0053] FIG. 2C is a schematic diagram showing an external spline structure 210 of a stator core 201 having teeth on its inner surface that engages with a corresponding internal spline structure having grooves 212 on the outer surface of a shaft 101, in accordance with some embodiments of the present disclosure, where the stator core 201 is attached to the same shaft 201 as the center of rotation of the rotor, thereby transmitting torque action and generating torque force.

[0054] FIG. 3 is a schematic diagram showing an axial flux rotor assembly according to some embodiments of the present disclosure. For example, FIG. 3 shows an axial flux rotor assembly 300 of a motor of the present disclosure, which may include one axial flux rotor housing 301, one axial flux rotor back-iron 302, and one axial flux PM array 303. The axial flux rotor back-iron is made of spiral electrical laminations, with lamination direction being radial. The axial flux PM array 303 is made of 2Pr arc-shaped magnets with alternating polarity, where Pr is the number of rotor pole pairs. The magnets are rigidly attached to the axial flux rotor back-iron 302 via structural adhesive. The axial flux rotor housing 301 may be made of structural aluminum alloy. The assembled 302 and 303 are also secured to the axial flux rotor housing 301 via structural adhesive.

[0055] FIG. 4 is a schematic diagram showing a radial flux rotor assembly according to some embodiments of the present disclosure. For example, FIG. 4 shows a radial flux rotor assembly 400 of a motor of the present disclosure, which may include one radial flux rotor housing 401, one radial flux rotor back iron 402, and one radial flux PM array 403. The radial flux rotor back iron may be made of a stack of electrical lamination pieces, and the lamination direction may be axial. The radial flux PM array 403 may also include 2Pr arc-shaped magnets with alternating polarity. The magnets are rigidly attached to the radial flux rotor back iron 402 via structural adhesive. The radial flux rotor housing 301 may be made of structural aluminum alloy, and has taped holes arranged on the axial surface. Finally, the assembled 402 and 403 are fixed to the radial flux rotor housing 301 by press fitting.

[0056] When the stator coils are excited with three-phase current, the stator generates a rotating magnetic field, which interacts with the rotor magnetic field to generate a torque on the rotor, accelerating the rotor or driving a load. P r =P s (1) , the motor forms a standard surface-mounted permanent magnet synchronous motor (PMSM).

[0057] The relationship between motor parameters is P r =Z s ±P s (2) (Z s is the number of stator slots in 202 and 203), the motor forms a Vernier Permanent Magnet Motor (VPM), and both the fundamental air-gap flux and the stator tooth harmonic air-gap flux participate in the torque generation. This motor utilizes the magnetic transmission effect, which allows for a larger torque generation compared to standard PMSM. The motor topology in this invention can be used with both standard PMSM motors and VPM motors.

[0058] FIG. 5 is a schematic diagram showing a thermal connection between a motor stator assembly and a hollow shaft for cooling, according to some embodiments of the present disclosure. For example, FIG. 5 shows that a stator coil 204 is wrapped around stator yokes 201, 202 and 203 assembled inside the slots. A thin layer of electrical insulation 501 is configured between the stator yoke 201 and the stator coil 202. The insulation 501 may be made of polyimide film or other standard slot insulation material for electric machines. When the stator assembly is properly positioned on the shaft, the stator coil 202 contacts the shaft 101 through a thermally conductive but electrically insulating epoxy 502. This epoxy layer 502 can effectively transfer heat from the coil into the shaft and further into the cooling channels 599.

[0059] FIG. 6 is a block diagram illustrating a motor drive and control system according to some embodiments of the present disclosure. For example, 6 shows a block diagram of a control system for a motor of the present invention. A motor 606 of the present invention is connected to a load 607 via a connection 615. The angular position of the motor is measured by position sensors (not shown), such as encoders and Hall effect sensors, and a measured angular position signal 616 is fed back to an analog-to-digital converter of a digital real-time controller 601. A reference trajectory signal 611 is generated by a reference trajectory generator 602. Both the measured position 616 of the motor and the reference trajectory 611 are fed to a motion controller 603, which generates a control effort signal 612 as a digital PWM signal. A DC power supply 604 generates a high voltage DC power 613, which feeds a DC bus to an inverter 605. The PWM signal 612 controls the gates in the inverter 605, which generates a high voltage signal 614 to energize windings in the motor 606. Such a control system allows the position of the motor to be controlled to follow a reference trajectory.

[0060] 7 is a schematic diagram illustrating some components of a computing system 707 having a processor 740 connected to a control system 762 of a machine (not shown), such as a PM machine or a similar type of machine, according to some embodiments of the present disclosure. For example, the processor 740 may be located proximate to or inside the machine (not shown). The processor 740 may be connected to a sensor 730, which is located inside the environment (not shown) and positioned within a sensing distance of the processor 740 and the machine (not shown). The sensor 730 may be a camera, a video camera, a speed sensor, a light sensor, an environment-related sensor (i.e., a temperature sensor, a humidity sensor, a fire sensor, an air sensor, a water sensor, an air pressure sensor, etc.) used with the machine (not shown). The sensor 730 may be connected by wires and / or wireless, such that the network 732 can be within an operating distance range of the sensor 730.

[0061] The processor 740 is connected to a bus system 722, which in turn is connected to a storage 742. The storage 742 may include a database 744, an instruction database 746, a history database (not shown), an instruction history database (not shown), an environmental database (not shown), a machine database (not shown) related to the operation of the machine, and other databases (not shown) that may have data regarding operations and information usable to optimize, manage, or operate the machine (not shown). Again, many different configurations are contemplated depending on each user / operator's particular operating configuration / configuration / special needs / protection needs of the intended use of the machine.

[0062] Continuing to refer to FIG. 7, memory 748 is connected to bus system 722 along with receiver interface 751, receiver 752, and power supply 755. Power supply 755 may be connected to bus system 722, connected to control interface 753, or configured to have numerous other configurations, all as intended depending on the intended special needs of a particular user / operator for operation. The power supply may be electrical, a renewable energy source, chemical, may be directly connected to the machine, may have multiple external power sources of different types, or both. Transmitter interface 757 and transmitter 759 are connected to bus system 722. Also connected to bus system 722 is network interface controller 750 (NIC) (also known as network interface card, network adapter, LAN adapter or physical network interface, and similar terms are computer hardware components that connect a computer to a computer network) which may communicate with network 732 or other different types of wireless networks (not shown). Again, depending on the special needs of operation and protection requirements required by the user / operator for the user / operator's intended use.

[0063] A control module 760 may be connected to the bus system 722. The control module 760 may be connected to a machine control computer 762, which helps to command the components of the machine control computer 762. Some components may include, as non-limiting examples, component 1 764, component 2 766, component 3 768, and other machine related components 769, all of which may be connected to the machine control computer 762 and / or to the control module 760 via 771. The control module 760 may be configured with the machine control computer 762 to provide machine management, operational optimization / performance by checking once and reporting back the status of the machine components, along with other related service and monitoring capabilities. The machine control computer may have a power module 774, which is intended to include any power source that provides power to the machine (not shown), such as a power adapter or a rechargeable battery pack, depending on the special requirements of the user.

[0064] Continuing to refer to FIG. 7, processor 740 can implement or execute stored instructions stored in memory 748, storage 742, or accessed from cloud storage via network 732; in particular, processor 740 can access pre-stored data including data from database 744, instruction database 746, or other stored data from other databases (not shown) as described above.

[0065] 7, a machine control computer 762 provides commands to one or more components of the machine associated with model aspects of the present disclosure to effect changes to the one or more components. It is contemplated that the computer system 707 may include a sensor control 773 connected to machine components 764, 766, 768. It is also contemplated that a number of component sensors (i.e., sensors associated with the machine or other components of the machine, or sensors associated with components associated with the machine), and other components (not shown), may be available. It is contemplated that multiple types of sensors may be located on the machine or in the vicinity of the machine.

[0066] The sensor control computer 773 may include a hardware processor (not shown) connected to a memory (not shown) containing stored software (not shown). The hardware processor (not shown) may implement or execute stored instructions stored in the memory (not shown) and upon receiving any sensor data, may compare the received data to the stored data and transmit sensor data / signals such as warning messages, levels of performance associated with one or more components of the machine to the machine control computer 762 or other components of the machine or computer system 707. Another aspect of the systems and components of this embodiment is that the software or hardware, or some combination thereof, may be implemented via localized storage or through a cloud-based system.

[0067] Additionally, the control or controller module 760 may include different applications and programs for implementing the methods of the present disclosure. For example, the control module 760 may include applications for processing information received from the machine control computer 762, such as creating graphs, motion related models including 3D models of the environment in which the machine is located. The control module 760 may include applications for interpreting control inputs or output signals received via the input circuitry / interface module 780, storage module 782, and for creating commands / actions.

[0068] Figure 8 is a schematic diagram illustrating a centralized controller system that can be used to implement certain methods or can be combined with the processor of Figure 7 depending on the particular objectives of a user, according to some embodiments of the present disclosure. For example, the centralized controller system can be a computing device representing various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other suitable computers.

[0069] The centralized controller system 800 may include a power supply 808, a processor 809, a memory 810, and a storage device 811, all of which are connected to a bus 850. Additionally, a high-speed interface 812, a low-speed interface 813, a high-speed expansion port 814, and a low-speed connection port 815 may be connected to the bus 850. Also, a low-speed expansion port 816 connects to the bus 850. Various component configurations are contemplated that may be mounted on a common motherboard 830, as a non-limiting example, depending on the particular application. Additionally, an input interface 817 may be connected to an external receiver 806 and an output interface 818 via the bus 850. A receiver 819 may be connected to an external transmitter 807 and a transmitter 820 via the bus 850. An external memory 804, an external sensor 803, a machine 802, and an environment 801 may also be connected to the bus 850. Additionally, one or more external input / output devices 805 may be connected to the bus 850. A network interface controller (NIC) 821 may be adapted to connect to a network 822 through a bus 850, and may, among other things, enable data or other data to be rendered on a third party display device, a third party imaging device, and / or a third party printing device external to the computing device 800.

[0070] It is intended that the memory 810 may store instructions executable by the centralized controller system 800, historical data, and any data that may be utilized by the methods and systems of the present disclosure. The memory 810 may include random access memory (RAM), read only memory (ROM), flash memory, or other suitable memory systems. The memory 810 may be one or more volatile memory units and / or one or more non-volatile memory units. The memory 810 may be another form of computer readable medium, such as a magnetic or optical disk.

[0071] Continuing with reference to FIG. 8, storage device 811 may be adapted to store supplemental data and / or software modules used by computer device 800. For example, storage device 811 may store historical data and other related data as described above with respect to this disclosure. Additionally or alternatively, storage device 811 may store historical data similar to that described above with respect to this disclosure. Storage device 811 may include a hard drive, an optical drive, a thumb-drive, an array of drives, or any combination thereof. Additionally, storage device 811 may include a computer-readable medium such as a floppy disk device, a hard disk device, an optical disk device, or an array of devices including a tape device, a flash memory or other similar solid-state memory device, or a storage area network or other configuration of devices. Instructions may be stored on an information carrier that, when executed by one or more processing units (e.g., processor 809), performs one or more methods, such as those described above.

[0072] The system can optionally be linked via bus 850 to a display interface or user interface (HMI) 823 adapted to connect the system to a display device 825 and a keyboard 824, which may include, among others, a computer monitor, a camera, a television, a projector, or a mobile device.

[0073] Continuing to refer to FIG. 8, the centralized controller system 800 may include a user input interface 817 adapted to a printer interface (not shown) that may also be connected over a bus 850 and adapted to connect to a printing device (not shown), which may include a liquid inkjet printer, a solid ink printer, a large scale commercial printer, a thermal printer, a UV printer, or a dye sublimation printer, among others.

[0074] The high-speed interface 812 manages the bandwidth-intensive operations of the computing device 800, while the low-speed interface 813 manages the less bandwidth-intensive operations. Such allocation of functions is merely an example. In some implementations, the high-speed interface 812 may be coupled to memory 810, a user interface (HMI) 823 (e.g., through a graphics processor or accelerator), and to a keyboard 824 and a display 825, and may also be coupled to a high-speed expansion port 814 that may accept various expansion cards (not shown) via a bus 850. In this implementation, the low-speed interface 813 is coupled to a storage device 811 and a low-speed expansion port 815 via a bus 850. The low-speed expansion port 815, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet), may be coupled to one or more input / output devices 805, and other devices such as a keyboard 824, a pointing device (not shown), a scanner (not shown), or a networking device such as a switch or router, for example, through a network adapter.

[0075] 8, the centralized controller system 800, as shown, may be implemented in a number of different forms. For example, it may be implemented as a standard server 826, or multiple times in a group of such servers. It may also be implemented in a personal computer, such as a laptop computer 827. It may also be implemented as part of a rack server system 828. Alternatively, components from the computing device 800 may be combined with other components in a mobile device (not shown), such as a mobile computing device having a different component configuration arranged for the mobile device.

[0076] 9A and 9B are schematic diagrams of outer runner motors, with FIG. 9A showing a Type I motor and FIG. 9B showing a Type II motor according to some embodiments of the present disclosure.

[0077] For example, Figure 9A shows a Type I machine with a stator and windings on the inside, but the windings are standard distributed windings, not of the toroidal winding variety. The rotor, rotor core and magnets are on the outside, with rotor bars and end rings. The disclosed embodiment does not have rotor bars and end rings.

[0078] Further, Figure 9B shows a Type II machine with a stator, windings and stator core on the inside, but the windings are standard concentrated windings and not of the toroidal winding variety. The rotor, rotor core and magnets are on the outside. However, both of the above types of machines have no axial flux section, whereas the embodiment of the present disclosure has two axial flux sections, a stator and rotor at both axial ends.

[0079] Practical Applications The embodiments of the present disclosure include improved motor configurations including combined axial and radial flux motor designs and outer runner electric motor designs configured for gearbox-less direct drive applications. These embodiments include stator assemblies that use stator yokes made of separate electrical laminations for the axial and radial flux stator yokes. Some aspects of having electrical laminations can include increasing the amount of torque of the motor and decreasing the amount of hysteresis loss of the motor. Also, by incorporating a stator assembly that uses a stator yoke made of separate electrical laminations, the central volume of the stator core can be replaced with non-ferromagnetic material, effectively reducing the overall weight of the motor, thus improving the torque-to-mass ratio of the motor. Among the above advantages and benefits, as well as others, the embodiments of the present disclosure can be utilized in various types of applications such as machine room-less elevators, robotic manipulators, high precision rotary stages, and in-wheel drives for electric vehicles.

[0080] Compared to conventional electric motors for general-purpose drivers, the embodiments of the present disclosure embodied in and with direct drive motors provide certain operational characteristics, such as having very high torque density, low nominal speed, and relatively high efficiency in a compact form factor. For example, the embodiments of the present disclosure achieve high specific torque (torque per unit mass), high torque density (torque per unit total volume). Other aspects of the embodiments of the present disclosure with direct drive motor designs may include relatively high efficiency, small torque ripple, in addition to having a compact form as described above. As such, and in view of the improved operational aspects described above, the embodiments of the present disclosure outperform conventional motors of the same size and type in various other application areas, such as, for example, machine room-less elevators, robot manipulators, high precision rotary stages, and in-wheel drives for electric vehicles, and direct drive electric motor applications without gearboxes.Some of the reasons why the direct drive electric motor application industry would prefer the embodiments of the present disclosure over conventional motors of the same size and type include: (a) the electric motor or motor drive architecture becomes more compact and lighter by effectively reducing the volume of the actuator assembly by eliminating the gearbox and replacing the stator core center with a lighter material; (b) gearbox failure is one of the main failure modes of geared motors, and the use of direct drive motors is more beneficial in terms of reliability since the gearbox is eliminated in addition to improving the total torque of the motor with the lighter stator core material and new splined structure; (c) the simplified actuator assembly without gearbox and the ability to use laminated sheets for the stator yoke help reduce the total manufacturing cost of the system; and (d) the improved stator assembly with the new stator core center and splined structure provides a longer-lasting motor in terms of increased operational wear and tear and abuse resistance in addition to eliminating the gearbox, which is undesirable for high precision applications, having nonlinear dynamics such as backlash hysteresis, nonlinear Coulomb friction, etc., and may reduce the dynamic performance of the system.

[0081] Thus, based on the innovative motor design configurations of the embodiments of the present disclosure, these configurations are specifically adapted to be utilized in a variety of applications, such as robotic manipulators, high precision rotary stages, and in-wheel drives for electric vehicles, where the desired attributes of electric machines having increased torque and specific torque, compact size, reduced overall weight, and other attributes associated with the above-mentioned advantages and benefits described herein, are superior to conventional motors of the same size and type for at least the reasons described herein.

[0082] Other uses of the innovative motor design configurations of the disclosed embodiments may further include various application areas such as machine tools, industrial machines, household appliances, electric vehicles, etc. Some other benefits and advantages of the disclosed embodiments may include reduced manufacturing costs of the stator by utilizing conventional electrical laminations, i.e., compared to conventional electric motors of the same size. Further benefits and advantages may include: (1) increased total torque of the motor due to increased material permeability; (2) reduced hysteresis losses; (3) compact size; (4) reduced total weight; and (5) improved performance. The above five advantages are based on comparing each of the above advantages to conventional motors or different types of conventional motors of the same size, and performance, motor size, motor volume, motor mass, motor weight, etc., associated with different types of conventional motors, for at least the reasons described herein.

[0083] Features According to an embodiment of the disclosure, an electric machine is provided that is an axial-flux and radial-flux motor, the electric machine including a rotor rotatably mounted about a machine axis, the rotor rotatably attached to a shaft. The stator assembly has a stator core using a non-ferromagnetic material. The radial-flux stator yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The first axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core. The second axial-flux stator yoke has an inner wall rigidly attached to an outer surface of a second end wall of the stator core. The radial-flux stator yoke and the first and second axial-flux stator yokes each include lamination sheets and slots. Windings are positioned in the slots of the radial-flux stator yoke and the first and second axial-flux stator yokes. The stator core and the shaft include splined coupling features adapted to selectively couple and mate the stator core to the shaft. The following aspects are intended to constitute improvements over the above-described embodiments in any one or combination of the following aspects.

[0084] In one aspect, the splined feature includes a stator core having an external spline formation and a shaft having a corresponding internal spline formation, the shaft adapted to be inserted into or extracted from the stator core, hi another aspect, the shaft is a hollow stationary shaft and the rotor is rotatably mounted to the stationary shaft with bearings.

[0085] In one aspect, two axial flux rotor assemblies are rotatably mounted on the shaft via bearings and engaged with the first and second axial flux stator yokes. Each axial flux rotor assembly has an axial flux rotor housing rigidly mounted to the outer ring of the bearing, an axial flux rotor backiron mounted to the axial flux rotor housing, and an axial flux permanent magnet array mounted to the axial flux rotor backiron. In one aspect, a radial flux rotor assembly is rigidly connected to the axial flux rotor housing of each axial flux rotor assembly of the two axial flux rotor assemblies and rotatably engaged with the radial flux stator yoke. The radial flux rotor assembly includes a radial flux rotor housing rigidly mounted to the axial flux rotor housing of each axial flux rotor assembly of the two axial flux rotor assemblies. A radial flux rotor back-iron is attached to the radial flux rotor housing and a radial flux permanent magnet array is attached to the axial flux rotor back-iron and the axial flux rotor housing of each axial flux rotor assembly of the two axial flux rotor assemblies.

[0086] In another aspect, the radial flux stator yoke and the first and second axial flux stator yokes include laminated sheets having one of a spiral electrical lamination, a stacked electrical lamination, a solid material or at least one power material compounded into the radial flux stator yoke and the first and second axial flux stator yokes. In one aspect, the non-ferromagnetic material of the stator core is a material that is one of a plastic, a carbon fiber reinforced polymer, a fiberglass, or a non-ferrous material.

[0087] In yet another aspect, the non-ferromagnetic material of the stator core comprises at least 90% of one or more non-ferromagnetic materials. In one aspect, the non-ferromagnetic material of the stator core may be one or more non-ferromagnetic metals derived from sulfide, carbonate, or silicate minerals and may be non-magnetic. In yet another aspect, the non-ferromagnetic material of the stator core may include a level of conductive material having a level of mechanical stiffness associated with one of titanium, fiberglass, or acetal homopolymer. In one aspect, the windings are thermally connected to the shaft, and the windings may be positioned within slots of the radial flux stator yoke and the first and second axial flux stator yokes to form a toroidal stator assembly.

[0088] According to another embodiment of the present disclosure, there is provided an electric machine that is an outer runner motor, the electric machine having a rotor rotatably mounted about a machine axis, the rotor rotatably attached to the shaft. The stator assembly has a stator core using a non-ferromagnetic material. The axial flux yoke has an inner wall rigidly attached to an outer surface of a first end wall of the stator core, or the radial flux yoke has a continuous inner wall rigidly attached to a continuous outer wall of the stator core. The axial flux yoke or the radial flux yoke includes laminated sheets and slots. Windings may be positioned in the slots of the axial flux stator yoke or the radial flux stator yoke. The stator core and the shaft include splined coupling features adapted to selectively couple and mate the stator core to the shaft. The following aspects are intended to constitute improvements of the above-mentioned embodiments in one or a combination of the following aspects:

[0089] In one aspect, the splined feature includes a stator core having an external splined structure and a shaft having a corresponding internal splined structure adapted to be inserted into or extracted from the stator core. In a further aspect, the external splined structure of the stator core includes teeth on an inner surface of an inner wall of the stator core that engage with corresponding internal splined structure having grooves on an outer surface of the shaft, and the stator core may be mounted on the same shaft as the center of rotation of the rotor to transfer torque action and generate torque forces.

[0090] In one aspect, the non-ferromagnetic material of the stator core comprises at least 85% of one or more non-ferromagnetic materials. In one aspect, the windings include a series of toroidal multi-phase windings, which can be configured in slots of an axial or radial flux stator yoke. In another aspect, the windings are thermally connected to the shaft, and the windings are positioned in slots of an axial or radial flux stator yoke to form a toroidal stator assembly. In yet another aspect, the windings are wound on an assembled stator yoke, which includes an axial or radial flux stator yoke, and the windings include a winding pattern having end turns, referred to as toroidal windings, which reduce the length of the end turns, which can result in an increased overall efficiency of the electric machine, as compared to a similarly configured electric machine without the toroidal windings. In a further aspect, the windings are wound on an assembled stator yoke, including an axial flux stator yoke or a radial flux stator yoke, the windings including multiple loops of magnetic copper wire and having three phases and pole pairs. In another aspect, the windings include a copper material and are wound on an assembled stator yoke, including an axial flux stator yoke or a radial flux stator yoke, the windings including a winding pattern having seat turns referred to as toroidal windings, which reduce the length of the seat turns and result in a total amount of copper loss in the motor's windings that increases the overall efficiency of the motor.

[0091] definition According to aspects of the present disclosure, the following definitions have been established based on experiments, but are by no means a complete definition of each phrase or term. The definitions provided are provided only as examples based on learning from experiments, and other interpretations, definitions, and other aspects may be relevant. However, such definitions are provided as at least a basic introduction to the phrase or term indicated.

[0092] Splined structure and keyed shaft :Splines are used in mechanical drive systems and can be found in rotating devices in daily life. Splines are raised ridges that transmit torque by engaging with grooves in connecting components. A splined shaft is usually a component in a variety of mechanisms that operate in linear motion. A keyed shaft is defined by two features: a shaft, and a rotating element with a keyway. A keyed shaft is usually a system in a variety of mechanisms that operate in rotary motion.

[0093] Unlike keyed shafts, splined shafts may have reduced torque transmission capabilities. Splines also provide a more uniform torque transmission and equal load distribution along the tooth sides of the gear. As a result, splined shafts are more likely to have a longer fatigue life and prevent wear and tear. Several different types of splines were tested during the experiment, including: (a) Helical splines. These splines have equal groove spacing between the teeth that form the helix, and are parallel or involute sided. This design is ideal in terms of allowing rotational and linear motion between the parts, as well as minimizing stress concentrations under high loads. (b) Crowned splines. Like helical splines, crowned splines also have involute equally spaced grooves. However, crowned splines have improved teeth that allow tolerance for potential misalignment. (c) Ball splines. These splined shafts have an external toothed section with ball bearings, allowing free linear motion despite high torque. (d) Parallel keyed splines. As the name suggests, the equally spaced grooves are parallel in both the radial and axial directions. Parallel key splines may be machined or formed by cold rolling. Of the two methods, rolled splines are 35% stronger, making them suitable for applications requiring precision, high strength while still providing a smooth finish. For these reasons, splined shafts are preferred over keyed shafts.

[0094] Splines are typically made up of both internal and external splines. External splines are cut on a milling machine, while internal splines are cut on a type of slotting machine. The manufacture of internal splines is more limited than external splines, as they tend to have more limited accessibility restrictions. External splines can be manufactured utilizing a variety of processes.

[0095] Torque: Torque is defined as the measurement of rotational force on a rotating object such as a bolt or an automobile flywheel. Torque is the measurement of rotational force on a rotating object such as a bolt or an automobile flywheel. Again, going back to basic physics, T=F*r, as shown in Figure 2, where T=torque, F=applied force, and r=radius of the arc along which the applied force follows. Torque is usually expressed in newton meters or foot-pounds.

[0096] Torque Density: Torque density is the ratio of torque capacity to volume in joules per cubic meter or foot-pounds per cubic foot. In other words, torque density measures the torque-carrying capacity of a component at its respective weight and space envelope. In other words, torque density measures the torque-carrying capacity of a component at its respective weight and space envelope. Why Torque Density is Important in Mechanical Design: In the design of mechanical systems, torque density can be used to make smarter design decisions. To use a consumer product analogy, purchasing choices are often mistakenly made based on "brute force" factors such as the wattage output of an amplifier, or the horsepower rating of a pressure washer's engine. A closer look would look at how efficiently an amplifier outputs a signal to its speaker, or the amount of water a pressure washer outputs at a particular pressure.

[0097] The payoff of using torque density in product design and selection. The need to deliver torque is often a complex challenge. Traditional approaches based on power or rotational speed can lead to unnecessarily bulky solutions. By using torque density as a key parameter, many payoffs can be achieved, including: (a) more efficient operation through less space; (b) reduced costs through optimal component selection; (c) innovative designs and new products; (d) longer equipment life through better matched components; and (e) reduced noise through smaller motors. By considering torque density first, designers, manufacturers, and end users can all benefit from smarter machine design.

[0098] Magnetization: Magnetization M results from the tendency of the atomic components of a material to behave like magnetic dipoles. This magnetization is the sum of two parts: the magnetization due to the magnetic polarization present in the material, and the magnetization due to the induced polarization. The former is the primary magnetization Mpri and the latter is the secondary magnetization. The primary magnetization is the magnetic field associated with a material in the absence of any external excitation. This field arises from the magnetic dipoles within the material. The secondary magnetization of a material is the polarization induced in the material by an external field.

[0099] Motor Windings: Motor windings can take many shapes and forms. However, three-phase distributed windings are most commonly used in AC motors for industrial applications, and this is what we will focus on in this article. The following description applies equally to the use of this type of winding in an induction motor or in a permanent magnet synchronous motor. The purpose of a distributed winding is to generate a sinusoidal magnetomotive force (MMF) distribution in the motor air gap. This MMF is generated when a balanced set of three-phase AC currents is passed through the phase windings. The MMF, combined with the motor magnetic circuit design, creates traveling waves of magnetic flux in the air gap to generate the required motor torque. A winding consists of several coils wound from insulated copper, or sometimes aluminum wire. Several wires can be connected in parallel to form a single conductor, which is then wound into a coil with several turns. The number of turns is determined by the specific design requirements. A distributed winding consists of several coils inserted into slots in the motor stator as shown below. The number of coils is determined by the number of stator slots, the number of phases (3 in this case), and the number of motor poles p. Each coil spans several slots. A full-pitch winding has coils corresponding to a number of slots whose average span is equal to the pole pitch or 360° / p, whereas a short-pitch winding spans fewer slots. The drawing below shows a full-pitch winding for a typical 4-pole motor. Part of the winding is in the slot and contributes to the motor torque production. The remaining part is at the end coils, which do not contribute to the motor torque production. Therefore, careful design is required to avoid wasting expensive copper. Furthermore, good thermal performance increases the need for high slot filling, and end coil thermal management. These factors are often limited by manufacturing process considerations. An ideal distributed winding would have an infinite number of coils arranged in an infinite number of slots such that the MMF spatial distribution is a perfect sine wave. This is obviously not possible in practice, so the best compromise needs to be found to meet the required performance. The coils of the different phases need to be insulated from each other and from the stator core to prevent short circuits and failures. Insulation provides an additional thermal barrier that limits the ability of heat to be transferred from the inside of the machine to the outside.Air gaps are created between the windings and between the insulation, windings and the stator core, which are filled with resin using an impregnation method, improving heat transfer and further improving the winding insulation.

[0100] Motor Winding Design: Winding designs for electric motor applications are diverse. Different applications impose different requirements on the motor design. Some of these requirements are influenced by the winding design and may include (a) minimizing harmonic losses for improved efficiency, (b) reducing torque pulsation, and (c) reducing acoustic noise and vibration. Several winding layouts are possible to achieve the same electrical performance. The choice of these layouts is dictated by manufacturing constraints, which are heavily influenced by the level of automation used to manufacture the windings.

[0101] Magnetic Flux: Magnetic flux is the existence of a force field in a specified physical medium or the flow of energy through a surface. In electronics, the term applies to any electrostatic field and any magnetic field. Magnetic flux is depicted as "lines" in a plane that contains or intersects the charge or magnetic poles.

[0102] Radial Flux: The magnetic flux in a radial flux motor is in and out of the center of the shaft, and is called "radial" because it is on a radius. The air gap, the space between the rotor and the magnets, can also describe the motor, but when looking at the air gap, the air gap should be thought of as a dimension.

[0103] Torque: Torque is a measure of a turning force that has the effect of rotating an object. In other words, torque is the product of force and distance. Torque is also called twisting force. The SI unit of torque is the newton meter, which is equal to a joule. An example of torque can be the force exerted by your hand to open or close a jar cap. The more force you exert, the greater the torque. Torque is also applied to tighten or loosen a nut with a wrench and to turn the steering wheel of a car. Torque = force x distance.

[0104] Embodiment The following description provides only exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the present disclosure. Rather, the following description of exemplary embodiments will provide those skilled in the art with an enabling description for implementing one or more exemplary embodiments. It is contemplated that various changes may be made to the function and configuration of elements without departing from the spirit and scope of the disclosed subject matter as set forth in the appended claims. Specific details are provided in the following description to provide a thorough understanding of the embodiments. However, those skilled in the art will understand that the embodiments may be practiced without these specific details. For example, systems, processes, and other elements in the disclosed subject matter may be shown as components in block diagram form so as not to obscure the embodiments in unnecessary detail. In other instances, well-known processes, structures, and techniques may be shown without unnecessary detail so as to avoid obscuring the embodiments. Additionally, like reference numbers and names in the various figures refer to like elements. Although the present disclosure has been described with reference to certain preferred embodiments, it should be understood that various other modifications and improvements are possible within the spirit and scope of the present disclosure.

Claims

1. 1. An electric machine which is an outer runner motor, A shaft provided along a machine axis; a rotor rotatably mounted on the shaft; a stator assembly having a stator core using a non-ferromagnetic material; the stator core is ring-shaped, having an inner periphery close to the shaft and an outer periphery distant from the shaft, and having a first end wall and a second end wall connecting the inner periphery and the outer periphery; The stator assembly includes: an axial-flux stator yoke having an inner wall rigidly attached to an outer surface of the first end wall of the stator core and an inner wall rigidly attached to an outer surface of the second end wall of the stator core; and a radial-flux stator yoke having a continuous inner wall rigidly attached to a continuous outer surface of the ring-shaped outer periphery of the stator core, the ring-shaped inner periphery of the stator core having no radial yoke; the axial flux stator yoke is provided to sandwich the stator core from the first end wall and the second end wall, The axial flux stator yoke or the radial flux stator yoke includes a lamination sheet and a slot, Windings are positioned in the slots of the axial flux stator yoke and the radial flux stator yoke; The stator core and the shaft include a splined engagement feature adapted to mate an inner wall of a ring-shaped inner circumference of the stator core with an outer surface of the shaft.

2. 2. The electric machine of claim 1, wherein the splined engagement features include the stator core having an external spline formation and the shaft having a corresponding internal spline formation, the shaft adapted to be inserted into or extracted from the stator core.

3. 3. The electric machine of claim 2, wherein the external spline structure of the stator core includes teeth on an inner surface of an inner wall of the stator core that engage with the corresponding internal spline structure having grooves on an outer surface of the shaft, and the stator core is mounted on the same shaft about which the rotor rotates, thereby transferring torque actions to secure the stator assembly to the shaft and transferring torque actions to maintain angular correspondence to generate torque forces.

4. 2. The electric machine of claim 1, wherein the windings include a series of toroidal multi-phase windings, the multi-phase windings being configured in the slots of an outer wall of the axial-flux stator yoke or of the radial-flux stator yoke.

5. 2. The electric machine of claim 1, wherein the windings are thermally connected to the shaft, and the windings are positioned in the slots of the axial-flux stator yoke or the radial-flux stator yoke to form the stator assembly in a toroidal manner.

6. 2. The electric machine of claim 1, wherein the windings are wound on an assembled stator yoke that includes the axial flux stator yoke or the radial flux stator yoke, and the windings include a winding pattern having an end turn referred to as a toroidal winding.

7. 2. The electric machine of claim 1, wherein the winding is wound around an assembled stator yoke that includes the axial flux stator yoke or the radial flux stator yoke, the winding including multiple loops of magnetic copper wire and having three phases and pole pairs.

8. 2. The electric machine of claim 1, wherein the windings comprise a copper material and are wound around an assembled stator yoke that includes the axial flux stator yoke or the radial flux stator yoke, and the windings include a winding pattern having an end turn referred to as a toroidal winding.

9. 2. The electric machine of claim 1, wherein the lamination sheets of the radial flux stator yoke and the axial flux stator yoke include one of a spiral electrical lamination, a stacked electrical lamination, a solid material or at least one power material blended into the radial flux stator yoke and the axial flux stator yoke.

10. The electric machine of claim 1 , wherein the non-ferromagnetic material of the stator core comprises at least 85% of one or more non-ferromagnetic materials.

11. The electric machine of claim 1 , wherein the non-ferromagnetic material of the stator core is one of the following: plastic, carbon fiber reinforced polymer, fiberglass, or a non-ferrous material.

12. The electric machine of claim 1 , wherein the non-ferromagnetic material of the stator core comprises one of the following materials: titanium, fiberglass, or acetal homopolymer.

13. An electric machine which is an outer runner motor and an axial-flux and radial-flux motor, A shaft provided along a machine axis; a rotor rotatably mounted on the shaft; a stator assembly having a stator core using a non-ferromagnetic material; the stator core is ring-shaped, having an inner periphery close to the shaft and an outer periphery distant from the shaft, and having a first end wall and a second end wall connecting the inner periphery and the outer periphery; The stator assembly includes: a radial flux stator yoke including a continuous inner wall rigidly attached to a continuous outer surface of the ring-shaped outer periphery of the stator core; a first axial-flux stator yoke having an inner wall rigidly attached to an outer surface of the first end wall of the stator core, and a second axial-flux stator yoke having an inner wall rigidly attached to an outer surface of the second end wall of the stator core, The ring-shaped inner peripheral surface of the stator core does not include a radial yoke, the axial flux stator yoke is provided to sandwich the stator core from the first end wall and the second end wall, the radial flux stator yoke and the first and second axial flux stator yokes each include a lamination sheet and a slot; Windings are positioned in the slots of the radial flux stator yoke and the first and second axial flux stator yokes; the stator core and the shaft include splined engagement features adapted to mate the shaft to the stator assembly; The splined coupling feature includes the stator core having an external spline formation on the inner circumference of the ring and the shaft having a corresponding internal spline formation on its outer circumference, the shaft adapted to be inserted into and extracted from the stator core.

14. The electric machine of claim 13 , wherein the shaft is a hollow stationary shaft and the rotor is rotatably mounted on the stationary shaft with a bearing.

15. 14. The electric machine of claim 13, further comprising two axial flux rotor assemblies rotatably mounted on the shaft via bearings and opposing the first and second axial flux stator yokes, each axial flux rotor assembly having an axial flux rotor housing rigidly mounted to an outer ring of the bearing, an axial flux rotor backiron mounted to the axial flux rotor housing, and an axial flux permanent magnet array mounted to the axial flux rotor backiron.

16. 16. The electric machine of claim 15, further comprising a radial flux rotor assembly rigidly connected to an axial flux rotor housing of each axial flux rotor assembly of the two axial flux rotor assemblies and rotatably opposing the radial flux stator yoke, the radial flux rotor assembly including: a radial flux rotor housing rigidly mounted to an axial flux rotor housing of each axial flux rotor assembly of the two axial flux rotor assemblies; a radial flux rotor back-iron mounted to the radial flux rotor housing; and a radial flux permanent magnet array mounted to the radial flux rotor back-iron and to the radial flux rotor housing.

17. The electric machine of claim 13 , wherein the non-ferromagnetic material of the stator core comprises at least 90% of one or more non-ferromagnetic materials.

18. 14. The electric machine of claim 13, wherein the non-ferromagnetic material of the stator core is one or more non-ferromagnetic metals derived from sulfide, carbonate, or silicate minerals and is a non-magnetic material.

19. 14. The electric machine of claim 13, wherein the windings are thermally connected to the shaft, the windings being positioned within the slots of the radial flux stator yoke and in outer walls of the first and second axial flux stator yokes to form a toroidal stator assembly.

20. 1. A system comprising: a transceiver for receiving signals from sensors associated with the outer runner motor and the axial and radial flux (AFARF) motor; and a digital controller configured to receive the signals and generate control signals specifying values ​​of one or a combination of polyphase voltages or currents of the AFARF motor to track a reference trajectory of torque of the AFARF motor, the AFARF motor having a load positioned by the AFARF motor and controllable by the digital controller, the AFARF motor comprising: a rotor rotatably mounted about a machine axis, said rotor being rotatably attached to a shaft; a stator assembly having a stator core using a non-ferromagnetic material; the stator core is ring-shaped, having an inner periphery close to the shaft and an outer periphery distant from the shaft, and having a first end wall and a second end wall connecting the inner periphery and the outer periphery; The stator assembly includes: a radial flux stator yoke including a continuous inner wall rigidly attached to a continuous outer surface of the ring-shaped outer periphery of the stator core; a first axial-flux stator yoke having an inner wall rigidly attached to an outer surface of the first end wall of the stator core, and a second axial-flux stator yoke having an inner wall rigidly attached to an outer surface of the second end wall of the stator core, The ring-shaped inner peripheral surface of the stator core does not include a radial yoke, the axial flux stator yoke is provided to sandwich the stator core from the first end wall and the second end wall, the radial flux stator yoke and the first and second axial flux stator yokes each include a lamination sheet and a slot; Windings are positioned in the slots of the radial flux stator yoke and the first and second axial flux stator yokes; The system, wherein the stator core and the shaft include a splined engagement feature adapted to mate an inner wall of a ring-shaped inner circumference of the stator core with an outer surface of the shaft.

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