Printed circuit board axial flux machine for steer-by-wire hand wheel actuator

Abstract

The invention relates to a printed circuit board axial flux machine for a steer-by-wire hand wheel actuator. An axial flux machine, namely an AFM, includes a rotor assembly configured to rotate about an axis. The rotor assembly includes a first rotor core and a second rotor core. The first rotor core and the second rotor core each have a plurality of permanent magnets attached thereto, and both the first rotor core and the second rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis. The AFM also includes a stator assembly having a PCB between and parallel to the first rotor core and the second rotor core. The PCB defines a stator winding configured to generate a magnetic flux through each of the first rotor core and the second rotor core in an axial direction such that the AFM generates a torque. A steer-by-wire system includes a hand wheel actuator that includes the AFM that is coupled to apply torque to a steering wheel.

Description

Technical Field

[0001] The present disclosure relates to an axial flux electric machine having printed circuit board (PCB) windings and the use of such an axial flux electric machine in a hand wheel actuator of a steering system of a vehicle. Background Art

[0002] Vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, boats, aircraft, all-terrain vehicles, RVs, or other suitable forms of transportation) typically include a steering system, such as an electric power steering (EPS) system, a steer-by-wire (SbW) steering system, a hydraulic steering system, or other suitable steering system. The steering system of such a vehicle typically controls various aspects of the vehicle's steering, including providing steering assistance to the operator of the vehicle, controlling the vehicle's steerable wheels, etc.

[0003] Steer-by-wire (SbW) is a direct evolution of the Electric Power Steering (EPS) system, where there is no mechanical connection between the handwheel and the steering rack. EPS systems may include a single actuator whose sole purpose is to provide assistance to the driver during steering maneuvers. However, on an SbW system, there may be two electric actuators / motors with different functionalities. The electric actuator attached to the rack in an SbW system is called a wheel actuator (RWA), while the actuator on the driver's side is called a handwheel actuator (HWA). The RWA has the same assistance-providing function as the EPS system actuator. On the other hand, the HWA is used more as a feedback motor rather than providing assistance to the driver. In the absence of the HWA, the handwheel on the SbW system would just idle due to the absence of any mechanical connection / friction. The HWA opens up a multitude of design-related opportunities due to its functionality.

[0004] The torque-speed curves of different actuators used in the steering system may also be different based on their functionality.The very different operating domains of EPS / RWA and HWA motivate the design exploration of HWA technology. Summary of the invention

[0005] The present disclosure generally relates to axial flux electric machines.

[0006] One aspect of the disclosed embodiment includes an axial flux machine (AFM). The AFM includes: a rotor assembly configured to rotate about an axis. The rotor assembly includes a first rotor core and a second rotor core, each of which has a plurality of permanent magnets attached thereto, and wherein the first rotor core and the second rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis. The AFM also includes a stator assembly. The stator assembly includes at least one PCB located between and parallel to the first rotor core and the second rotor core. The at least one PCB defines a stator winding configured to generate a magnetic flux passing through each of the first rotor core and the second rotor core in an axial direction so that the AFM generates torque.

[0007] One aspect of the disclosed embodiment includes a steer-by-wire system for a vehicle. The steer-by-wire system includes a handwheel actuator coupled to apply torque to a steering wheel. The handwheel actuator includes an axial flux machine (AFM). The AFM includes a rotor assembly configured to rotate about an axis. The rotor assembly includes a first rotor core and a second rotor core, each of the first rotor core and the second rotor core having a plurality of permanent magnets attached thereto, and wherein the first rotor core and the second rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis. The AFM also includes a stator assembly. The stator assembly includes at least one PCB located between and parallel to the first rotor core and the second rotor core. The at least one PCB defines a stator winding configured to generate a magnetic flux passing through each of the first rotor core and the second rotor core in an axial direction so that the AFM generates torque.

[0008] These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present disclosure is best understood from the following embodiments when read in conjunction with the accompanying drawings. It should be emphasized that, according to common practice, the various features of the drawings are not drawn to scale. Instead, the sizes of the various features are arbitrarily enlarged or reduced for clarity.

[0010] Figure 1 is a schematic diagram of an electric power steering (EPS) system in accordance with the principles of the present disclosure.

[0011] Figure 2 An electric power steering (EPS) system according to the principles of the present disclosure is generally illustrated.

[0012] Figure 3A steer-by-wire (SbW) steering system according to the principles of the present disclosure is generally illustrated.

[0013] Figure 4 is a schematic diagram of a motor drive system according to the principles of the present disclosure.

[0014] Figure 5 A graph illustrating a torque-speed curve for a steering system actuator according to the principles of the present disclosure is shown.

[0015] Figure 6 A cross-sectional view of a radial flux machine (RFM) according to the principles of the present disclosure is shown.

[0016] Figure 7 Shown is a cross-sectional view of an axial flux machine (AFM) according to the principles of the present disclosure.

[0017] Figure 8 A cross-sectional view of a first AFM assembly having a slotted stator core is shown.

[0018] Fig. 9 A cross-sectional view of a second AFM assembly having a stator core with a slotless stator core in accordance with the principles of the present disclosure is shown.

[0019] Fig.10 A cross-sectional view of a third AFM assembly according to the principles of the present disclosure is shown, wherein two rotor cores extend in parallel and are spaced apart from one another, and wherein the stator assembly includes two PCBs in a parallel arrangement and located between the two rotor cores.

[0020] Fig.11 A cross-sectional view of an AFM apparatus according to the principles of the present disclosure is shown, wherein each set of two rotor cores extend in parallel and are spaced apart from each other, and wherein the stator assembly comprises two sets of PCBs, each set of PCBs being in a parallel arrangement and located between corresponding sets of two rotor cores.

[0021] Fig.12 Shown is a cross-sectional view of a fourth AFM assembly including a passively damped PCB in accordance with the principles of the present disclosure.

[0022] Fig.13 A cross-sectional view of a fifth AFM assembly having a short-circuited winding within or between two PCBs is shown.

[0023] Fig.14 A schematic diagram of stator windings within an AFM is shown in accordance with the principles of the present disclosure.

[0024] Fig.15 A graph illustrating braking torque as a function of speed for an AFM with shorted windings having different numbers of turns is shown in accordance with the principles of the present disclosure.

[0025] Fig.16 Graphs showing short circuit current as a function of speed for AFMs with short circuit windings having different numbers of turns, in accordance with the principles of the present disclosure, are shown.

[0026] Fig.17 A schematic diagram of stator windings within an AFM with switch braking according to the principles of the present disclosure is shown.

[0027] Fig.18 Graphs showing braking torque as a function of speed for an AFM with shorted windings having different resistances are shown in accordance with the principles of the present disclosure.

[0028] Fig.19 Graphs showing short circuit current as a function of speed for AFM for short circuit windings with different resistances are shown in accordance with the principles of the present disclosure.

[0029] Fig. 20 Graphs showing torque versus time according to the principles of the present disclosure include curves representing the braking torque of an AFM with passive braking, the torque produced by active windings, and the total torque.

[0030] Fig.21 A PCB assembly according to the principles of the present disclosure is shown, partially cut away to illustrate various winding configurations. DETAILED DESCRIPTION

[0031] The following discussion is directed to various embodiments of the present disclosure. Although one or more of these embodiments may be preferred, the disclosed embodiments should not be interpreted or otherwise used to limit the scope of the present disclosure (including the claims). In addition, it will be understood by those skilled in the art that the following description has a wide range of applications, and the discussion of any embodiment is only meant to illustrate the embodiment, and is not intended to imply that the scope of the present disclosure (including the claims) is limited to the embodiment.

[0032] As described, a vehicle (such as a car, truck, sport utility vehicle, crossover, minivan, boat, airplane, all-terrain vehicle, RV or other suitable form of transportation) typically includes a steering system, such as an EPS system, a SbW steering system, a hydraulic steering system or other suitable steering system. The steering system of such a vehicle typically controls various aspects of the vehicle's steering, including providing steering assistance to the operator of the vehicle, controlling the vehicle's steerable wheels, etc.

[0033] The present disclosure provides an axial flux machine (AFM) that is particularly well suited for geared structures and high speed operation. The AFM may include a modular, spatially displaced three-phase or multi-phase stator structure. The AFM may include a printed circuit board (PCB) structure and a slotless stator topology. The AFM may be composed of a single or multiple rotor stacks with high volumetric torque density and weight torque density. The AFM can be relatively easily and efficiently manufactured and can provide suitable performance for a variety of applications in EPS and / or SbW systems.

[0034] The present disclosure provides an AFM structure to provide damping during power failure and fault conditions of a motor. The number of layers of a PCB can be shortened to achieve damping, or a separate PCB can be introduced to achieve damping of the motor. In addition, the number of turns and trace width of the coil in the shortened PCB can be completely different from the active PCB of the machine. Additional resistors can be used with the shortened PCB to control the short-circuit current and braking torque of the machine. These additional resistors can be implemented directly in the PCB to reduce the manufacturing difficulty and overall cost of the machine. In addition, additional circuits as well as gate drivers and switches can be implemented in the PCB to control the connection of the coil according to the operating speed. These additional circuits can also be implemented in the same PCB to reduce the cost and manufacturing difficulty of the machine.

[0035] Figure 1 is a schematic diagram of an electric power steering system (EPS) 40 suitable for implementing the disclosed technology. The EPS includes a steering mechanism 36, which includes a rack and pinion type mechanism having a rack (not shown) located within a housing 50 and a pinion (also not shown) located below a gear housing 52. When an operator input, hereinafter represented as a steering wheel 26 (e.g., a hand wheel, etc.), is turned, an upper steering shaft 29 is rotated, and a lower steering shaft 51 connected to the upper steering shaft 29 by a universal joint 34 rotates the pinion. Rotation of the pinion moves the rack, which moves tie rods 38 (only one shown), which in turn move steering knuckles 39 (only one shown), which rotate steerable wheels 44 (only one shown).

[0036] The electric power steering assistance is provided by a steering motion control system generally indicated by reference numeral 24 and includes a controller 16 and an electric machine, which may be a permanent magnet synchronous motor and is hereinafter indicated as motor 19. The controller 16 is powered by a vehicle power supply 10 through a supply conductor 12. The controller 16 receives a vehicle speed signal 14 representing the vehicle speed from a vehicle speed sensor 17. The steering angle is measured by a position sensor 32, which may be an optically encoded sensor, a variable resistance sensor, or any suitable type of position sensor, and provides a position signal 20 to the controller 16. The motor speed may be measured by a tachometer or any other device and sent to the controller 16 as a speed signal 21. Expressed as ω m The motor speed can be measured, calculated, or a combination of both. For example, the motor speed ω m can be calculated as the change in motor position as measured by the position sensor 32 over a specified time interval. For example, the motor speed ω m can be determined as the motor position θ m Derivative with respect to time. It will be appreciated that there are many well-known methods for performing derivative functions.

[0037] When the steering wheel 26 is turned, the torque sensor 28 senses the torque applied to the steering wheel 26 by the vehicle operator. The torque sensor 28 may include a torsion bar (not shown) and a variable resistor type sensor (also not shown) that outputs a torque signal 18 related to the amount of twist on the torsion bar to the controller 16. Although this is one type of torque sensor, any other suitable torque sensing device used with known signal processing techniques will be sufficient. In response to various inputs, the controller sends a command 22 to the motor 19, which provides torque assistance to the steering system through the worm 47 and the worm gear 48, thereby providing torque assistance to the vehicle steering.

[0038] It should be noted that although the disclosed embodiments are described by reference to motor control for electric steering applications, it should be understood that such references are merely illustrative and the disclosed embodiments may be applied to any motor control application employing an electric motor, such as steering, valve control, etc. In addition, the references and descriptions herein may be applied to many forms of parameter sensors, including but not limited to torque, position, speed, etc. It should also be noted that the electric machines referenced herein include but are not limited to motors, and hereinafter, for the sake of brevity and simplicity, only motors will be referenced without limitation.

[0039] In the steering motion control system 24 as depicted, the controller 16 uses torque, position, speed, etc. to calculate a command for delivering the required output power. The controller 16 is configured to communicate with various systems and sensors of the motor control system. The controller 16 receives signals from each system sensor, quantifies the received information, and provides an output command signal in response thereto, in this case, for example, to the motor 19. The controller 16 is configured to generate a corresponding voltage from an inverter (not shown), which may be optionally combined with the controller 16 and will be referred to as the controller 16 in this article, so that when applied to the motor 19, a desired torque or position is generated. In one or more examples, the controller 16 operates in a feedback control mode (as a current regulator) to generate the command 22. Alternatively, in one or more examples, the controller 16 operates in a feedforward control mode to generate the command 22. Because these voltages are related to the position and speed of the motor 19 and the desired torque, the position and / or speed of the rotor and the torque applied by the operator are determined. The position encoder is connected to the steering shaft 51 to detect the angular position θ. The encoder can sense the rotational position based on optical detection, magnetic field changes, or other methods. Typical position sensors include potentiometers, resolvers, synchronizers, encoders, etc., and combinations comprising at least one of the foregoing. The position encoder outputs a position signal 20 that indicates the angular position of the steering shaft 51 and thereby the angular position of the motor 19 .

[0040] The desired torque may be determined by one or more torque sensors 28 that send a torque signal 18 indicative of the applied torque. Such torque sensors 28 and the torque signal 18 therefrom may be responsive to a flexible torsion bar, spring, or similar device (not shown) configured to provide a response indicative of the applied torque.

[0041] In one or more examples, the temperature sensor 23 is located at the motor 19. Preferably, the temperature sensor 23 is configured to directly measure the temperature of the sensing portion of the motor 19. The temperature sensor 23 sends a temperature signal 25 to the controller 16 to facilitate the processing and compensation specified herein. Typical temperature sensors include thermocouples, thermistors, thermostats, etc., and combinations including at least one of the foregoing sensors, which provide a calibratable signal proportional to a specific temperature when properly placed.

[0042] Position signal 20, speed signal 21, and torque signal 18, among others, are applied to controller 16. Controller 16 processes all input signals to generate values ​​corresponding to each signal, thereby producing rotor position values, motor speed values, and torque values ​​that can be used for processing in the algorithm specified herein. Measurement signals (such as those described above) are also typically linearized, compensated, and filtered as needed to enhance the characteristics of the acquired signal or eliminate its undesirable characteristics. For example, this signal can be linearized to increase processing speed, or to address the large dynamic range of the signal. In addition, frequency or time-based compensation and filtering can be used to eliminate noise or avoid undesirable spectral characteristics.

[0043] In order to perform the specified functions and the desired processing, and calculations therefor (e.g., identification of motor parameters, control algorithms, etc.), the controller 16 may include, but is not limited to, a processor, a computer, a DSP, a memory, a storage device, a register, a timing, an interrupt, a communication interface, and an input / output signal interface, etc., and a combination including at least one of the foregoing. For example, the controller 16 may include input signal processing and filtering to enable accurate sampling and conversion or acquisition of such signals from the communication interface.

[0044] As used herein, variables with a tilde (~) above the variable symbol represent an approximation, which may be determined by mathematical calculations, lookup tables, etc. Variables with a bar above the variable symbol represent vectors. Variables with a superscript asterisk (*) represent commanded or desired set point values.

[0045] Figure 2 An electric power steering (EPS) system is generally illustrated, and Figure 3 A steer-by-wire (SbW) steering system is generally illustrated. Figure 2 The EPS system can be similar to or equivalent to Figure 1 The EPS system 40 differs in that the motor 19 is mounted directly to the steering mechanism 36 . Figure 2 The SbW system can be similar to or equivalent to Figure 1 The EPS system 40 of FIG. 1 is different in that there is no physical linkage between the steering wheel 26 and the steerable wheels 44 and there are two separate and independent motors 19a, 19b. As shown, the SbW system includes a first motor 19a (also known as a hand wheel actuator (HWA)) configured to provide torque to the steering wheel 26 for providing tactile feedback to the driver.

[0046] Steer-by-wire (SbW) is a direct evolution of the Electric Power Steering (EPS) system, where there is no mechanical link between the steering wheel 26 and the steering rack. Figure 2As can be seen in the , an EPS system may include a single actuator 19 whose sole purpose is to provide assistance to the driver during steering maneuvers. However, on an SbW system, there are two electric actuators / motors with different functions. The electric actuator on the driver's side is referred to as the handwheel actuator (HWA) 19a, while the electric actuator attached to the steering mechanism 36 in the SbW system is referred to as the wheel actuator (RWA) 19b. The RWA 19b can provide the same assistance function as the actuator 19 in the EPS system. On the other hand, the HWA 19a is used more as a feedback motor rather than providing assistance to the driver. In the absence of the HWA 19a, the handwheel on the SbW system will simply spin due to the absence of any mechanical connection / friction.

[0047] Figure 4 A motor control system 100 is shown having a dual-winding permanent magnet synchronous motor (DW-PMSM) (also referred to as a dual-winding synchronous machine (DWSM) or dual-winding motor 60), power converters 66a and 66b (each power converter includes a gate driver and a corresponding inverter), and a motor controller 70 (also referred to as a controller). The dual-winding motor 60 can be used in any number of applications, such as for Figure 1 The motor 19 in the steering motion control system 24 shown, or for either the HWA 19a or the RWA 19b. The power converters 66a and 66b may include a number of switching devices, such as field effect transistors (FETs) for switching high current loads and gate driver circuits for operating the switching devices.

[0048] The dual-winding motor 60 includes a first winding set 62a and a second winding set 62b electrically independent of the first winding set 62a. The dual-winding motor 60 is capable of generating electromagnetic torque by energizing either or both of the winding sets 62a, 62b. The two winding sets 62a and 62b may each include three phases, and thus each of the two winding sets 62a, 62b may include a three-phase winding. Alternatively, each of the winding sets 62a, 62b may include any number of winding phases, such as five or seven phases. In some embodiments, the dual-winding motor 60 is a multi-phase permanent magnet synchronous machine (PMSM). Each of the winding sets 62a, 62b may function separately, and the dual-winding motor 60 may be operated by energizing either or both of the winding sets 62a, 62b.

[0049] The motor control system 100 includes a controller 150. The controller 150 may include any suitable controller. The controller 150 may be configured to control various functions of the vehicle system, such as described herein. The controller 150 may include a processor 152 and a memory 154. The processor 152 may include any suitable processor, such as the processor described herein. Additionally or alternatively, in addition to or different from the processor 152, the controller 150 may include any suitable number of processors. The memory 154 may include a single disk or multiple disks (e.g., a hard disk drive), and include a storage management module that manages one or more partitions within the memory 154. In some embodiments, the memory 154 may include flash memory, semiconductor (solid-state) memory, etc. The memory 154 may include a random access memory (RAM), a read-only memory (ROM), or a combination thereof. The memory 154 may include instructions that, when executed by the processor 152, cause the processor 152 to at least control various functions of the steering system and / or any other suitable functions, including those of the systems and methods described herein.

[0050] The controller 150 may receive one or more signals indicating sensed or measured characteristics of the vehicle from various measuring devices or sensors. These sensors may include any suitable sensors, measuring devices, and / or other suitable mechanisms. For example, these sensors may include one or more torque sensors or devices, one or more steering wheel position sensors or devices, one or more motor position sensors or devices, one or more motor angle sensors or devices, other suitable sensors or devices, or combinations thereof. The one or more signals may indicate steering wheel torque, steering wheel angle, motor angle or motor position, vehicle speed, other suitable information, or combinations thereof.

[0051] The power converters 66a and 66b are configured to supply an alternating current (AC) voltage to the winding sets 62a and 62b, respectively. The winding sets 62a, 62b are connected to their respective power converters 66a, 66b via phase leads (motor leads) 68a and 68b. This configuration can provide redundancy, allowing the dual winding motor 60 to continue to function even in the event of a complete loss or failure of one of the winding sets 62a, 62b, one of the motor leads 68a, 68b, and / or one of the power converters 66a, 66b. The power converters 66a, 66b can be implemented with electrical isolation to obtain additional redundancy.

[0052] The controller 150 may be configured to generate a torque command based on the motor torque T e * Or generate voltage commands by other means And the voltage command is supplied to each of the power converters 66a, 66b. For example, the controller 150 may include a voltage command generator (not shown) to generate a voltage command using one or more optimizations and / or causing the electric motor drive system to satisfy one or more operating constraints, such as constraints on voltage and / or current generated by or supplied to the electric motor drive system. Feedforward voltage control techniques may include techniques provided in the present disclosure, but other feedforward control techniques may also be used.

[0053] The power converters 66a and 66b are configured to supply an alternating current (AC) voltage to the winding sets 62a and 62b, respectively. The winding sets 62a, 62b are connected to their respective power converters 66a, 66b via phase leads (motor leads) 68a and 68b. This configuration can provide redundancy, allowing the dual winding motor 60 to continue to function even in the event of a complete loss or failure of one of the winding sets 62a, 62b, one of the motor leads 68a, 68b, and / or one of the power converters 66a, 66b. The power converters 66a, 66b can be implemented with electrical isolation to obtain additional redundancy.

[0054] Figure 5 Graphs illustrating torque-speed curves for steering system actuators 19, 19a and 19b are shown. Different steering system actuators 19, 19a, 19b have different speed curves based on their functionality. Figure 5 As indicated by the dashed lines in , the EPS actuator 19 and RWA 19b in the SbW each operate in the first quadrant (Q1) of the torque-speed curve. The positive direction of the velocity in Q1 indicates that the actuator acts in the same direction as the driver's handwheel movement and provides assistance. However, as indicated by the solid lines, the HWA 19a of the SbW system operates primarily in the second quadrant (Q2) of the torque-speed curve. The HWA 19a moves opposite to the driver's handwheel movement (velocity -ve) and provides feedback to the driver. This feedback may be necessary to provide the driver with general steering feel and road condition feedback. In addition, some low-speed assistance (Q1 operation) from the HWA 19a may also be required, such as Figure 5 Visible in.

[0055] The HWA 19a may include an electric motor coupled to apply torque to the steering wheel 26 configuration, such as a worm gear drive, belt drive, and / or direct drive. In the case of worm gear and belt drive, a low torque (approximately 3 Newton meters (Nm)) and high speed (approximately 3000 revolutions per minute (RPM)) PMSM may be used as an actuator. Both surface mounted PMSM (SPMSM) and interior PMSM (IPMSM) topologies may be used for such HWA architectures. In addition, due to their similarities (in terms of torque-speed range), a large number of components may be directly transferred from a column EPS (CEPS) system to a worm gear or belt driven SbW handwheel system.

[0056] The torque-speed curves of the different actuators used in the steering system also vary based on their functionality. Figure 5 As shown, the EPS actuator and RWA in the SbW system each operate in the first quadrant (Q1) of the torque-speed curve. The positive direction of velocity in Q1 indicates that the actuator is acting in the same direction as the driver's handwheel movement and providing assistance. However, the SbW HWA operates primarily in the second quadrant (Q2) of the torque-speed curve. The HWA moves opposite to the driver's handwheel movement (velocity -ve) and provides feedback to the driver. This feedback is necessary to provide general steering feel and road condition feedback to the driver. In addition, some low-speed assistance (Q1 operation) from the HWA may also be required, such as Figure 5 The very different operation domains of EPS / RWA and HWA motivate the design exploration of HWA technology.

[0057] The HWA may include an electric motor coupled to apply torque to the steering wheel 26 configuration, such as a worm gear drive, belt drive, and / or direct drive. In the case of worm gear and belt drive, a low torque (approximately 3Nm) and high speed (approximately 3000RPM) PMSM may be used as an actuator. Both surface mounted PMSM (SPMSM) and interior PMSM (IPMSM) topologies may be used for such HWA architectures. In addition, due to their similarities (in terms of torque-speed range), a large number of components may be directly transferred from a column EPS (CEPS) system to a worm gear or belt driven SbW handwheel system.

[0058] Figure 6 A cross-sectional view of a radial flux machine (RFM) is shown. Figure 7 A cross-sectional view of an axial flux machine (AFM) is shown. Each of the RFM device and the AFM device includes a shaft configured to rotate about an axis A. A classification between RFM configurations and AFM configurations can be made based on the direction of the magnetic flux.

[0059] Figure 6The RFM includes a first rotor assembly 110a having a first rotor core 112a attached for rotation with a first shaft 114a about an axis A. The rotor assembly 110a is located within a first housing 115a, and the first shaft 114a extends through and outside the first housing 115a and is supported by a pair of first bearings 116a. A set of first permanent magnets 118a are attached to the first rotor core 112a and generate magnetic flux extending radially outward. Figure 7 The RFM also includes a first stator assembly 120a having a first stator core 122a with a set of first windings 124a extending therethrough and carrying current in an axial direction parallel to the axis A and perpendicular to the magnetic flux.

[0060] Figure 7 The AFM includes a second rotor assembly 110b having a second rotor core 112b attached so as to rotate with a second shaft 114b about an axis A. The second rotor assembly 110b is located within a second housing 115b, and the second shaft 114b extends through and outside the second housing 115b and is supported by a pair of second bearings 116b. A set of second permanent magnets 118b is attached to the second rotor core 112b and generates a magnetic flux extending in an axial direction parallel to the axis A. Figure 8 The AFM also includes a second stator assembly 120b having a second stator core 122b with a set of second windings 124b extending through the second stator core and carrying current in a radial direction perpendicular to the axis A and perpendicular to the magnetic flux.

[0061] like Figure 6 As shown, the magnetic flux in the RFM extends mainly in the radial direction perpendicular to the axis A. Figure 7 As shown, the magnetic flux in the AFM extends primarily in an axial direction parallel to the axis A. The RFM configuration and the AFM configuration can each provide different volumetric power densities and gravimetric power densities.

[0062] The present disclosure provides an axial flux machine (AFM) topology for a gear-driven SbW HWA architecture. An axial flux machine (AFM) has the potential to provide significant power density advantages over conventional radial flux machines in the high-speed, low-torque operating region of a gear-driven SbW HWA.

[0063] Figure 8A cross-sectional view of a first AFM assembly 200 having a slotted stator core is shown. The first AFM assembly 200 includes a rotor assembly 210 and a first stator assembly 220 having a first stator core 222. The rotor assembly 210 is attached to a motor shaft and is configured to rotate around an axis (not shown) while the first stator assembly 220 remains stationary. The rotor assembly 210 includes a rotor core 212 extending in a flat plane perpendicular to the axis of rotation. The rotor assembly 210 includes two permanent magnets 214a, 214b disposed on a surface of the first rotor core 212 facing the first stator assembly 220. The first stator core 222 defines two teeth 224, each having an I-shaped cross-section and extending toward a corresponding one of the two permanent magnets 214a, 214b. The first stator assembly 220 also includes a first winding 226 disposed around each of the two teeth 224 of the first stator core 222.

[0064] Fig. 9 A cross-sectional view of a second AFM assembly 250 according to the principles of the present disclosure is shown. The second AFM assembly 250 includes a rotor assembly 210 that is similar or identical to the rotor assembly 210 of the first AFM assembly 200. The second AFM assembly 250 also includes a second stator assembly 260, which can be referred to as a slotless stator because it does not include teeth 224 or corresponding slots between the teeth. Instead, the second stator assembly 260 includes a second stator core 262 and a printed circuit board (PCB) 264 that is attached to the second stator core and extends parallel to and spaced apart from the rotor core 212.

[0065] Fig.10 A cross-sectional view of a third AFM assembly 280 according to the principles of the present disclosure is shown. The third AFM assembly 280 includes a dual PCB, dual rotor design, and a stator core without any magnetic material (such as steel). The third AFM assembly 280 includes two rotor assemblies 210, each of which may be similar or identical to the rotor assembly 210 of the first AFM assembly 200. The two rotor assemblies 210 each have a rotor core 212, which are spaced apart and parallel to each other and perpendicular to the axis of rotation (not shown in the figure). The two rotor assemblies 210 each also include a plurality of permanent magnets 214a, 214b, which are disposed on the surface of the corresponding rotor core 212 and face the other rotor assembly of the two rotor assemblies 210.

[0066] The third AFM assembly 280 further includes a first active PCB 264a and a second active PCB 264b, which are adjacent to each other and are each located between and parallel to the two rotor cores 212. The first active PCB 264a and the second active PCB 264b each define a stator winding ( Fig.12), the stator winding is configured to generate a magnetic flux passing through each of the two rotor cores 212 in an axial direction so that the third AFM assembly 280 generates torque. As shown, the magnetic flux defines a closed loop path 282.

[0067] In some embodiments, the third AFM assembly 280 can be configured as a dual winding device.For example, the first active PCB 264a can define a first winding set 62a, and the second active PCB 264b can define a second winding set 62b.

[0068] Fig.11 A cross-sectional view of an AFM device 300 according to the principles of the present disclosure is shown. The AFM device 300 may also be referred to as an AFM. The AFM device 300 includes a two-stage structure in which two third AFM assemblies 280 are each coupled to a motor shaft 314 to rotate about an axis A. Each of the third AFM assemblies 280 in the AFM device 300 may also be referred to as an AFM stage. It should be understood that this is merely an example and that the AFM may be configured to have a different number of AFM assemblies 280.

[0069] The AFM device 300 includes a housing 315 extending around a motor shaft 314, wherein a bearing 316 supports the motor shaft 314 so that the motor shaft 314 can rotate around the axis. The AFM device 300 includes four rotor assemblies 210, each of which may be similar or identical to the rotor assembly 210 of the first AFM assembly 200, and each of which includes a rotor core 212 attached to the motor shaft 314 by a rotor support 302. These rotor cores 212 are spaced apart from each other and are parallel to each other and perpendicular to the axis A. The AFM device 300 also includes two groups of two active PCBs 264a, 264b, wherein each group of active PCBs 264a, 264b is disposed between and parallel to two corresponding rotor cores in the rotor core 212. Each of the active PCBs 264a, 264b can be held in a stationary position by a PCB support 304 attached to the housing 315.

[0070] Fig.12A cross-sectional view of a fourth AFM assembly 350 according to the principles of the present disclosure is shown. The fourth AFM assembly 350 may be similar or identical to the third AFM assembly 280, wherein a passive damping PCB 352 is added between the first active PCB 264a and the second active PCB 264b. The passive damping PCB 352 defines one or more passive damping windings 372, each of which has a short-circuit configuration to generate a braking torque. In some embodiments, the passive damping windings 372 of the passive damping PCB 352 may be permanently connected in a short-circuit configuration so that the passive damping PCB 352 always generates a constant braking torque. Alternatively or additionally, some or all of the passive damping windings 372 of the passive damping PCB 352 may be selectively connected in a short-circuit configuration. For example, the passive damping windings 372 may be selectively switched to a short-circuit configuration, thereby allowing selective generation of a braking torque and / or varying the magnitude of the braking torque.

[0071] Fig.13 A cross-sectional view of a fifth AFM assembly 370 according to the principles of the present disclosure is shown. The fifth AFM assembly 370 may be similar or identical to the third AFM assembly 280, wherein a passive damping winding 372 is attached within either or both of the first active PCB 264a and / or the second active PCB 264b. The passive damping winding 372 may have a short-circuit configuration to generate a braking torque. In some embodiments, the passive damping winding 372 may be permanently connected in a short-circuit configuration so that the passive damping winding 372 always generates a constant braking torque. Alternatively or additionally, some or all of the passive damping windings 372 may be selectively connected in a short-circuit configuration. For example, the passive damping winding 372 may be selectively switched to a short-circuit configuration, thereby allowing selective generation of a braking torque and / or changing the magnitude of the braking torque.

[0072] Fig.14An electrical schematic diagram of the stator windings within the fourth AFM assembly 350 is shown. As shown, the fourth AFM assembly 350 includes a first active PCB 264a that defines each of the A-phase stator winding 266a, the B-phase stator winding 266b, and the C-phase stator winding 266c. Each of the stator windings 266a, 266b, 266c includes four coils that have a parallel configuration between corresponding motor leads labeled as phase A, phase B, and phase C and a common neutral line. The second active PCB 264b has a similar configuration, defining each of the D-phase stator winding 266d, the E-phase stator winding 266e, and the F-phase stator winding 266f. Therefore, the stator windings 266a, 266b, 266c of the first active PCB 264a and the stator windings 266d, 266e, 266f of the second active PCB 264b each have a Y-shaped (Wye) connection. Alternatively, the stator windings may have a delta configuration. Each of the four coils comprising each of the stator windings may have a resistance of 550 milliohms (550 mΩ). However, the coils may have different resistances, and the stator windings 266a, 266b, 266c may have different numbers of constituent coils.

[0073] Fig.14 Also shown is an electrical schematic diagram of the passive damping PCB 352, including passive damping coils 268a, 268b, 268c constituting a passive damping winding 372. As shown, the passive damping winding 372 includes four first passive damping coils 268a, each of which is connected in series and connected in series with a first additional resistor 270a. The passive damping winding 372 also includes four second passive damping coils 268b, each of which is connected in series and connected in series with a second additional resistor 270b. The passive damping winding 372 also includes four third passive damping coils 268c, each of which is connected in series and connected in series with a third additional resistor 270c. However, any series combination may have a different number of passive damping coils 268a, 268b, 268c. Each of the series combinations of the passive damping coils 268a, 268b, 268c is connected in parallel with the corresponding additional resistors 270a, 270b, 270c. The additional resistors 270a, 270b, 270c are optional and may provide additional braking torque to be generated and / or limit the short circuit current generated in the passive damping winding 372, thereby protecting the passive damping winding 372 from overcurrent conditions that may cause permanent damage (such as breakage of the passive damping winding 372).

[0074] Figure 15 to Figure 16Graphs showing braking torque and short-circuit current as a function of speed for AFMs having twenty-five turns (NT=25) and fifty turns (NT=50), respectively, of the passive damping winding 372 are shown. As shown, for each case, the braking torque and short-circuit current each increase linearly with speed, and the AFM with NT=25 produces twice the braking torque and only slightly more short-circuit current than the AFM with NT=50.

[0075] Fig.17 An electrical schematic diagram of the stator windings within the fifth AFM assembly 370 is shown. As shown, the fifth AFM assembly 370 includes a first active PCB 264a that defines each of the A-phase stator winding 266a, the B-phase stator winding 266b, and the C-phase stator winding 266c. Each of the stator windings 266a, 266b, 266c includes four coils that have a parallel configuration between corresponding motor leads labeled as phase A, phase B, and phase C and a common neutral line. The second active PCB 264b has a similar configuration, defining each of the D-phase stator winding 266d, the E-phase stator winding 266e, and the F-phase stator winding 266f. Therefore, the stator windings 266a, 266b, 266c of the first active PCB 264a and the stator windings 266d, 266e, 266f of the second active PCB 264b each have a Y-shaped connection. Alternatively, the stator windings may have a triangular configuration. Each of the four coils comprising each of the stator windings may have a resistance of 550 milliohms (550 mΩ). However, the coils may have different resistances, and the stator windings 266a, 266b, 266c may have different numbers of constituent coils.

[0076] Fig.17It is also shown that each of the first active PCB 264a and the second active PCB 264b defines one or more passive damping windings 372, which can be operated in a short circuit configuration to generate a braking torque. As shown, the passive damping windings 372 of each of the first active PCB 264a and the second active PCB 264b include two first hybrid damping windings 272a, which are connected in series with each other and with a first switch 274a, which is configured to selectively conduct current through the first hybrid damping windings 272a so that the first hybrid damping windings 272 generate a braking torque. The passive damping winding 372 of each of the first active PCB 264a and the second active PCB 264b further includes two second hybrid damping windings 272b, which are connected in series with each other and with a second switch 274b, which is configured to selectively conduct current through the second hybrid damping windings 272b so that the second hybrid damping windings 272b generate additional braking torque. The passive damping winding 372 of each of the first active PCB 264a and the second active PCB 264b further includes two third hybrid damping windings 272c, which are connected in series with each other and with a third switch 274c, which is configured to selectively conduct current through the third hybrid damping windings 272c so that the third hybrid damping windings 272c generate additional braking torque. In some embodiments, some or all of the hybrid damping windings 272a, 272b, 272c can be connected to the motor leads to serve as additional stator windings.

[0077] Fig.17 Also shown is each of the first active PCB 264a and the second active PCB 264b including a switch driver 276 configured to control the operation of the switches 274a, 274b, 274c. Thus, each of the switches 274a, 274b, 274c and the switch driver 276 may be disposed within or on the first active PCB 264a and / or the second active PCB 264b. The switch driver 276 may control the individual operation of the switches 274a, 274b, 274c to produce varying amounts of braking torque.

[0078] Fig.18 A graph showing the braking torque of an AFM as a function of speed for shorted windings with different resistances is shown. Fig.19 A graph showing the short circuit current as a function of speed for the AFM for short circuit windings with different resistances is shown. Fig.18 and Fig.19The curves of the additional resistance Radd of 0Ω, 0.364Ω, 0.72Ω and 1.1Ω are included respectively. These different values ​​of the additional resistance Radd can be determined based on the number and / or configuration of the hybrid damping windings 272a, 272b, 272c short-circuited by the switches 274a, 274b, 274c. Therefore, the slope of the braking torque and the short-circuit current can be changed based on the number of the hybrid damping windings 272a, 272b, 272c that are shortened.

[0079] Fig. 20 Graphs of torque versus time are shown, including curves representing the braking torque of an AFM with passive braking operating at 750 RPM, the torque produced by the active windings, and the total torque. Fig. 20 The graph shows second quadrant (Q2) operation, where the total torque can be the sum of the braking torque generated by the passive damping coils 268a, 268b, 268c and / or the hybrid damping windings 272a, 272b, 272c and the active torque generated by the stator windings 266a, 266b, 266c of the active PCBs 264a, 264b.

[0080] Fig.21 A passive damping PCB 352 is shown with portions cut away to show various different winding configurations for the passive damping PCB 352. The various different winding configurations include: lap windings (a), concentric windings (b), radial lap windings (c), and arc windings (d). Similar or identical winding configurations may be used in either or both of the active PCBs 264a, 264b. The passive damping windings may be connected differently from the active windings and in this manner achieve the desired braking torque.

[0081] The present disclosure provides an axial flux machine (AFM). The AFM includes: a rotor assembly configured to rotate around an axis and including a first rotor core and a second rotor core, each of which has a plurality of permanent magnets attached thereto, and the first rotor core and the second rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis; and a stator assembly including at least one PCB located between and parallel to the first rotor core and the second rotor core. The at least one PCB defines a stator winding configured to generate a magnetic flux passing through each of the first rotor core and the second rotor core in an axial direction so that the AFM generates torque.

[0082] In some embodiments, the AFM further comprises a motor shaft extending along the axis, and each of the first rotor core and the second rotor core is attached to the motor shaft to rotate with the motor shaft, and the first rotor core and the second rotor core are each circumferentially disposed around the motor shaft.

[0083] In some embodiments, the at least one PCB includes a first PCB and a second PCB, the first PCB and the second PCB each extending parallel to each other and each located between and parallel to the first rotor core and the second rotor core.

[0084] In some embodiments, the stator windings include a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings is operable to generate the magnetic flux and cause the rotor assembly to generate torque.

[0085] In some embodiments, the at least one PCB includes a first PCB and a second PCB, each of which extends parallel to each other and is each located between and parallel to the first rotor core and the second rotor core; and the first PCB defines the first set of active windings, and the second PCB defines the second set of active windings.

[0086] In some embodiments, the AFM further comprises: a second rotor assembly configured to rotate about the axis and comprising a third rotor core and a fourth rotor core, each of the third rotor core and the fourth rotor core having a plurality of permanent magnets attached thereto, and the third rotor core and the fourth rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis; and a second stator assembly comprising at least one second PCB located between and parallel to the third rotor core and the fourth rotor core. In some embodiments, the at least one second PCB defines a second stator winding configured to generate a magnetic flux passing through each of the third rotor core and the fourth rotor core in an axial direction so that the AFM generates torque.

[0087] In some embodiments, the stator winding is a phase winding of a plurality of phase windings, and wherein the at least one PCB defines each phase winding of the plurality of phase windings.

[0088] In some embodiments, the at least one PCB further comprises a passive damping winding having one or more short circuit configurations to generate a braking torque.

[0089] In some embodiments, the at least one PCB further comprises a resistor connected to the passive damping winding.

[0090] In some embodiments, the at least one PCB includes: an active PCB defining the stator winding, the stator winding being configured to generate the magnetic flux; and a passive damping PCB independent of the active PCB and defining the passive damping winding.

[0091] In some embodiments, the stator winding includes a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings is operable to generate the magnetic flux and cause the rotor assembly to generate torque. In some embodiments, the at least one PCB includes a first PCB and a second PCB, the first PCB and the second PCB each extending parallel to each other and each located between and parallel to the first rotor core and the second rotor core, wherein the first PCB defines the first set of active windings and the second PCB defines the second set of active windings. In some embodiments, the AFM further includes a passive damping PCB defining the passive damping winding, the passive damping PCB being disposed adjacent to and parallel to each of the first PCB and the second PCB.

[0092] In some embodiments, the AFM further includes a hybrid damper winding having a switch configured to selectively conduct current through the hybrid damper winding such that the hybrid damper winding generates a braking torque.

[0093] In some embodiments, the AFM further comprises a switch driver configured to control operation of the switch, and wherein the hybrid damping winding, the switch and the switch driver are each disposed within or on the at least one PCB.

[0094] In some embodiments, the AFM further comprises a plurality of hybrid damping windings and a plurality of switches, wherein each of the switches is configured to selectively conduct current through a corresponding one or more of the plurality of hybrid damping windings. In some embodiments, changing the configuration of the plurality of switches to conduct the current through the corresponding one or more windings causes the AFM to generate a varying amount of braking torque.

[0095] In some embodiments, the plurality of hybrid damping windings and the plurality of switches are each disposed within or on the at least one PCB.

[0096] The present disclosure provides a steer-by-wire system for a vehicle. The steer-by-wire system includes a handwheel actuator that is coupled to apply torque to a steering wheel. The handwheel actuator includes an axial flux machine (AFM). The AFM includes a rotor assembly that is configured to rotate about an axis. The rotor assembly includes a first rotor core and a second rotor core, each of which has a plurality of permanent magnets attached thereto, and the first rotor core and the second rotor core are spaced apart from each other and parallel to each other and perpendicular to the axis. The AFM also includes a stator assembly. The stator assembly includes at least one PCB located between and parallel to the first rotor core and the second rotor core. The at least one PCB defines a stator winding that is configured to generate a magnetic flux that passes through each of the first rotor core and the second rotor core in an axial direction so that the AFM generates torque.

[0097] In some embodiments, the at least one PCB includes a first PCB and a second PCB, the first PCB and the second PCB each extending parallel to each other and each located between and parallel to the first rotor core and the second rotor core.

[0098] In some embodiments, the stator windings include a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings is operable to generate the magnetic flux and cause the rotor assembly to generate torque.

[0099] In some embodiments, the at least one PCB further comprises a passive damping winding having one or more short circuit configurations to generate a braking torque.

[0100] In some embodiments, the at least one PCB further comprises a resistor connected to the passive damping winding.

[0101] The above discussion is intended to illustrate the principles and various embodiments of the present disclosure. Once the above disclosure is fully understood, many changes and modifications will become apparent to those skilled in the art. The appended claims are intended to be interpreted as covering all such changes and modifications.

[0102] The word "example" is used herein to mean used as an example, instance or illustration. Any aspect or design described as an "example" herein is not necessarily to be interpreted as being preferred or advantageous over other aspects or designs. On the contrary, the use of the word "example" is intended to present the concept in a specific way. As used in this application, the term "or" is intended to represent an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clearly known from the context, "X includes A or B" is intended to represent any one of the natural inclusive permutations and combinations. That is, if X includes A; X includes B; or X includes both A and B, "X includes A or B" is satisfied under any of the aforementioned examples. In addition, the articles "one" and "an" as used in this application and the appended claims should generally be interpreted as meaning "one or more", unless otherwise specified or clearly from the context to refer to the singular form. In addition, the use of the term "one embodiment" or "one embodiment" throughout the text is not intended to represent the same embodiment or embodiment, unless specifically described as such.

[0103] The embodiments of the systems, algorithms, methods, instructions, etc. described herein may be implemented in hardware, software, or any combination thereof. The hardware may include, for example, a computer, an intellectual property (IP) core, an application specific integrated circuit (ASIC), a programmable logic array, an optical processor, a programmable logic controller, microcode, a microcontroller, a server, a microprocessor, a digital signal processor, or any other suitable circuit. In the claims, the term "processor" should be understood to include any of the foregoing hardware, either alone or in combination. The terms "signal" and "data" are used interchangeably.

[0104] As used herein, the term module may include: a packaged functional hardware unit designed for use with other components; a set of instructions executable by a controller (e.g., a processor executing software or firmware); a processing circuit configured to perform a specific function; and an independent hardware or software component that interfaces with a larger system. For example, a module may include an application specific integrated circuit (ASIC); a field programmable gate array (FPGA); an electrical circuit; a digital logic circuit; an analog circuit; a combination of discrete circuits; a gate; and other types of hardware; or a combination thereof. In other embodiments, a module may include a memory that stores instructions that are executable by a controller to implement the features of the module.

[0105] Furthermore, in one aspect, for example, a general purpose computer or general purpose processor with a computer program can be used to implement the system described herein, which when executed implements any of the corresponding methods, algorithms and / or instructions described herein. Additionally or alternatively, for example, a special purpose computer / processor can be utilized, which may include other hardware for implementing any of the methods, algorithms or instructions described herein.

[0106] In addition, all or part of the embodiments of the present disclosure may take the form of a computer program product accessible from, for example, a computer usable medium or a computer readable medium. A computer usable medium or a computer readable medium may be any device capable of, for example, tangibly containing, storing, transferring or transmitting a program for use by or in conjunction with any processor. The medium may be, for example, an electronic, magnetic, optical, electromagnetic or semiconductor device. Other suitable media are also available.

[0107] The above embodiments, specific implementations and aspects have been described to allow easy understanding of the present disclosure, and do not limit the present disclosure. On the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, and its scope should be given the broadest interpretation to cover all such modifications and equivalent structures permitted under the law.

Claims

1. An axial flux machine, comprising: a rotor assembly configured to rotate about an axis and including a first rotor core and a second rotor core, each having a plurality of permanent magnets attached thereto, and each being spaced apart from and parallel to each other and perpendicular to the axis; as well as a stator assembly including at least one printed circuit board located between and parallel to the first rotor core and the second rotor core, Wherein the at least one printed circuit board defines a stator winding configured to generate a magnetic flux through each of the first rotor core and the second rotor core in an axial direction such that the axial flux machine produces torque.

2. The axial flux machine of claim 1 , further comprising a motor shaft extending along the axis, wherein each of the first rotor core and the second rotor core is attached to the motor shaft to rotate with the motor shaft, and wherein the first rotor core and the second rotor core are each circumferentially disposed around the motor shaft.

3. The axial flux machine of claim 1 , wherein the at least one printed circuit board comprises a first printed circuit board and a second printed circuit board, the first printed circuit board and the second printed circuit board each extending parallel to each other and each being located between and parallel to the first rotor core and the second rotor core.

4. An axial flux machine according to claim 1, wherein the stator windings include a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings is operable to generate the magnetic flux and cause the rotor assembly to produce torque.

5. The axial flux machine of claim 4, wherein the at least one printed circuit board comprises a first printed circuit board and a second printed circuit board, the first printed circuit board and the second printed circuit board each extending parallel to each other and each being located between and parallel to the first rotor core and the second rotor core; and The first printed circuit board defines the first set of active windings, and the second printed circuit board defines the second set of active windings.

6. The axial flux machine of claim 1 , further comprising: a second rotor assembly configured to rotate about the axis and including a third rotor core and a fourth rotor core, the third rotor core and the fourth rotor core each having a plurality of permanent magnets attached thereto, and the third rotor core and the fourth rotor core each being spaced apart from each other and parallel to each other and perpendicular to the axis; as well as a second stator assembly, the second stator assembly comprising at least one second printed circuit board located between and parallel to the third rotor core and the fourth rotor core, Wherein the at least one second printed circuit board defines a second stator winding configured to generate a magnetic flux passing through each of the third rotor core and the fourth rotor core in an axial direction so that the axial flux machine generates torque.

7. The axial flux machine of claim 1, wherein the stator winding is one phase winding of a plurality of phase windings, and wherein the at least one printed circuit board defines each phase winding of the plurality of phase windings.

8. The axial flux machine of claim 1, wherein the at least one printed circuit board further comprises a passive damping winding having one or more short circuit configurations to generate a braking torque.

9. The axial flux machine of claim 8, wherein said at least one printed circuit board further comprises a resistor connected to said passive damping winding.

10. The axial flux machine of claim 8, wherein the at least one printed circuit board comprises: an active printed circuit board, the active printed circuit board defining the stator winding, the stator winding being configured to generate the magnetic flux; and a passive damping printed circuit board that is independent of the active printed circuit board and defines the passive damping winding.

11. The axial flux machine of claim 8, wherein the stator windings include a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings are operable to generate the magnetic flux and cause the rotor assembly to produce torque, wherein the at least one printed circuit board comprises a first printed circuit board and a second printed circuit board, the first printed circuit board and the second printed circuit board each extending parallel to each other and each being located between and parallel to the first rotor core and the second rotor core, wherein the first printed circuit board defines the first set of active windings and the second printed circuit board defines the second set of active windings, and The axial flux machine further includes a passive damping printed circuit board defining the passive damping winding, the passive damping printed circuit board being disposed adjacent to and parallel to each of the first printed circuit board and the second printed circuit board.

12. The axial flux machine of claim 1 further comprising a hybrid damper winding having a switch configured to selectively conduct current through the hybrid damper winding such that the hybrid damper winding produces a braking torque.

13. The axial flux machine of claim 12, further comprising a switch driver configured to control operation of the switch, and wherein the hybrid damping winding, the switch and the switch driver are each disposed within or on the at least one printed circuit board.

14. The axial flux machine of claim 1 , further comprising a plurality of hybrid damping windings and a plurality of switches, wherein each of the switches is configured to selectively conduct current through a corresponding one or more of the plurality of hybrid damping windings, and in, Changing the configuration of the plurality of switches to conduct the current through the corresponding one or more windings will cause the axial flux machine to produce a varying amount of braking torque.

15. The axial flux machine of claim 14, wherein the plurality of hybrid damper windings and the plurality of switches are each disposed within or on the at least one printed circuit board.

16. A steer-by-wire system for a vehicle, comprising: a hand wheel actuator coupled to apply torque to the steering wheel; The hand wheel actuator comprises an axial flux machine, the axial flux machine comprising: a rotor assembly configured to rotate about an axis and including a first rotor core and a second rotor core, each having a plurality of permanent magnets attached thereto, and wherein the first rotor core and the second rotor core are each spaced apart from and parallel to each other and perpendicular to the axis; as well as a stator assembly including at least one printed circuit board located between and parallel to the first rotor core and the second rotor core, Wherein the at least one printed circuit board defines a stator winding configured to generate a magnetic flux through each of the first rotor core and the second rotor core in an axial direction such that the axial flux machine produces torque.

17. The steer-by-wire system of claim 16, wherein the at least one printed circuit board comprises a first printed circuit board and a second printed circuit board, wherein the first printed circuit board and the second printed circuit board each extend parallel to each other and are each located between and parallel to the first rotor core and the second rotor core.

18. The steer-by-wire system of claim 16, wherein the stator windings include a first set of active windings and a second set of active windings independent of the first set of active windings, wherein either the first set of active windings or the second set of active windings are operable to generate the magnetic flux and cause the rotor assembly to produce torque.

19. The steer-by-wire system of claim 16, wherein the at least one printed circuit board further comprises a passive damping winding having one or more short circuit configurations to generate a braking torque.

20. The steer-by-wire system of claim 19, wherein the at least one printed circuit board further comprises a resistor connected to the passive damping winding.

Images