Variable flux augmented motor using iron nitride permanent magnets

Abstract

A rotor for an electric machine has pairs of magnets disposed in the rotor near an exterior of the rotor. Magnets having a coercivity (Hci) of 2,000 Oe to 4,000 Oe are positioned so that the poles are aligned with an axis of rotation of the rotor and are secured to the rotor by a high permeability material. Each pair of magnets has similar poles facing each other, and each magnet has a longitudinal axis aligned with a d-axis of the rotor. The rotor includes a first non-magnetic and non-conductive member having a longitudinal axis aligned with a q-axis of the rotor and a second non-magnetic and non-conductive member having a curved region that is recessed relative to a surface of the rotor. The magnets are centered relative to the second non-magnetic and non-conductive member to be disposed in the curved region.

Description

[0001] Cross-reference of related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 555,842, filed February 20, 2024, and U.S. Provisional Application No. 63 / 676,107, filed July 26, 2024, the disclosures of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0003] This disclosure relates generally to electric motors, and more specifically to electric motors that realize permanent magnets. Background Technology

[0004] Motors (such as electric motors and generators) typically use neodymium (NdFeB) magnets and other permanent magnet materials, many of which contain rare earth elements (such as samarium cobalt (SmCo) and samarium iron nitride (SmFeN) magnets) and other strategic / critical minerals (such as cobalt in AlNiCo), the supply of which may be restricted and / or disrupted. Specifically, rare earth magnets are preferred because the degree to which a rare earth permanent magnet synchronous motor (PMSM) can be weakened by magnetic flux is limited due to the high coercivity, or intrinsic coercivity (Hci), of rare earth magnets.

[0005] Externally excited motors, such as induction motors and brushed DC motors, can achieve very high speeds, for example, by reducing the external excitation; however, their efficiency is significantly lower than that of PMSMs. Known motor designs using AlNiCo (which is a low coercivity (LCF) magnet) are also prone to demagnetization under high stator currents. Permanent magnet motors (especially generators) implementing this design can pose serious and potentially fatal safety problems when the motor control electronics or the windings of such a motor design experience short-circuit faults. For example, when a continuous voltage is generated, current flows unrestricted through the machine due to: (i) overheating of the motor due to the flow of eddy currents induced by the magnetic field of the rotating rotor, (ii) overheating of the motor due to the unrestricted current flow in the coil windings, and / or (iii) high voltage on the motor housing (which should be at ground) due to eddy currents induced by the magnetic field of the rotating rotor.

[0006] Therefore, there is a need for electric motors that do not use any rare earth metals or strategic / critical minerals, as well as systems that can effectively control the operation of such motors to reduce the risk of failure caused by demagnetization, as is commonly found in known permanent magnet motors that do not use such rare earth metals or strategic / critical minerals. Summary of the Invention

[0007] This article discloses an example of a variable flux-enhanced motor using permanent magnets with low coercivity, such as ferronitride.

[0008] According to one example (“Example 1”), the rotor includes multiple pairs of magnets disposed in the rotor near the outer portion of the rotor. The magnets have a coercivity (Hci) of 2,000 Oe to 4,000 Oe; the magnets are positioned such that their poles are aligned with the rotational axis of the rotor; the magnets are fixed to the rotor by a highly permeable material; each pair of magnets has similar magnetic poles facing each other; and each magnet has a longitudinal axis aligned with the d-axis of the rotor. Multiple first non-magnetic and non-conductive components are disposed in the rotor. Each of the first non-magnetic and non-conductive components has a longitudinal axis aligned with the q-axis of the rotor. Multiple second non-magnetic and non-conductive components are disposed in the rotor near the outer portion of the rotor. Each of the second non-magnetic and non-conductive components has a curved region recessed relative to the surface of the rotor and an end near the surface of the rotor. The magnets are centered relative to the second non-magnetic and non-conductive components such that each magnet is disposed in the curved region.

[0009] According to another example (“Example 2”) that goes further than Example 1, the second non-magnetic and non-conductive component includes a smaller radius component and a larger radius component having a larger radius than the smaller radius component. The smaller radius component is positioned closer to the surface of the rotor than the larger radius component.

[0010] According to another example (“Example 3”) that goes further than Example 1 or 2, the surface of the rotor has multiple recesses that approximate the magnet.

[0011] According to another example (“Example 4”) that goes further than any of Examples 1 to 3, the magnets are arranged adjacent to each other along the axis of rotation of the rotor.

[0012] According to another example (“Example 5”) that goes further than any of Examples 1 to 4, each magnet in the magnet has a volume weight ratio greater than 0.1.

[0013] According to another example (“Example 6”) that goes further than any of Examples 1 to 5, each magnet in the magnet has a permeability from 1.8 to 2.0.

[0014] According to another example (“Example 7”) that goes further than any of Examples 1 to 6, the magnet includes an iron nitride (FeN) magnet.

[0015] According to another example (“Example 8”) that goes further than any of Examples 1 to 7, one of the pairs of magnets includes a first magnet and a second magnet, such that the first N pole of the first magnet faces the second N pole of the second magnet.

[0016] According to another example (“Example 9”) that goes further than any of Examples 1 to 7, one of the pairs of magnets includes a first magnet and a second magnet, such that the first N pole of the first magnet faces the second N pole of the second magnet.

[0017] According to another example (“Example 10”) that goes further than any of Examples 1 to 9, each of the first non-magnetic and non-conductive components has a lateral distance measured perpendicular to the longitudinal axis of the first non-magnetic and non-conductive component, and the lateral distance measured along the longitudinal axis of the first non-magnetic and non-conductive component is consistent.

[0018] According to another example (“Example 11”) that goes further than any of Examples 1 to 9, each of the first nonmagnetic and nonconductive components has a lateral distance measured perpendicular to the longitudinal axis of the first nonmagnetic and nonconductive component, and the lateral distance varies along the longitudinal axis of the first nonmagnetic and nonconductive component such that the lateral distance measured near the outer portion of the rotor is longer than the lateral distance measured near the inner portion of the rotor.

[0019] According to another example (“Example 12”) that goes further than any of Examples 1 to 9, each of the first nonmagnetic and nonconductive components has a lateral distance measured perpendicular to the longitudinal axis of the first nonmagnetic and nonconductive component, and the lateral distance varies along the longitudinal axis of the first nonmagnetic and nonconductive component such that the lateral distance measured near the outer portion of the rotor is shorter than the lateral distance measured near the inner portion of the rotor.

[0020] According to another example (“Example 13”) that goes further than any of Examples 1 to 12, one or more of the first non-magnetic and non-conductive component and the second non-magnetic and non-conductive component are made of plastic or resin.

[0021] According to another example (“Example 14”) that goes further than any of Examples 1 to 13, the magnets and the first non-magnetic and non-conductive components are arranged in an interleaved configuration, wherein each of the first non-magnetic and non-conductive components is disposed between two adjacent magnets in a plurality of pairs of magnets.

[0022] According to another example (“Example 15”), an electric motor includes a stator and a rotor according to any one of Examples 1 to 14, and the rotor is disposed in the stator.

[0023] According to one example (“Example 16”), a method of operating an electric motor having a rotor according to any one of Examples 1 to 14, the method comprising: receiving a torque command by a controller operably coupled to the rotor; and the controller performing a flux-enhancing operation by operating the rotor based on the torque command to generate a positive reluctance torque and aligning the stator current distribution with the positive d-axis of the rotor such that the total torque reaches a maximum at a negative current angle within the range of the rotor’s flux-enhancing operation, wherein the inductance on the d-axis of the rotor is greater than the inductance on the q-axis of the rotor.

[0024] According to one example (“Example 17”), a method of operating a rotor includes: receiving a torque command and a speed command by a controller operably coupled to the rotor; determining an operating type of the rotor by the controller based on the torque command and the speed command; and operating the rotor by applying a current to the rotor according to the determined operating type. The operating type is selected from one of the following: (a) high torque / low speed operation, wherein the rotor operates in a flux-enhancing region of the current angle; (b) medium torque / speed operation, wherein the rotor operates in a zero magnetization region of the current angle; and (c) low torque / high speed operation, wherein the rotor operates in a flux-decrease region of the current angle. The rotor includes multiple pairs of magnets disposed near the exterior of the rotor. The magnets have a coercivity (Hci) of 2,000 Oe to 4,000 Oe, and are positioned such that their poles are aligned with the rotational axis of the rotor. Each pair of magnets has similar poles facing each other, and each magnet has a longitudinal axis aligned with the d-axis of the rotor.

[0025] According to another example (“Example 18”) that goes further than Example 17, in high torque / low speed operation, the rotor is operated to provide a torque that is at least 60% of the rotor’s maximum torque and a speed that is no more than 30% of the rotor’s maximum speed.

[0026] According to another example (“Example 19”) that goes further than Example 17, in medium-range torque / speed operation, the rotor is operated to provide torque between 30% and 60% of the rotor’s maximum torque and speed between 30% and 60% of the rotor’s maximum speed.

[0027] According to another example (“Example 20”) that goes further than Example 17, in low torque / high speed operation, the rotor is operated to provide a torque of no more than 30% of the rotor’s maximum torque and a speed of at least 60% of the rotor’s maximum speed.

[0028] According to one example (“Example 21”), a method of manufacturing a rotor for an electric motor includes: providing a rotor body comprising a plurality of laminations constructed for stacking, the rotor body having a plurality of first slots, a plurality of second slots, and a plurality of third slots; arranging a plurality of pairs of magnets in the first slots, wherein the magnets have a coercivity (Hci) of 2,000 Oe to 4,000 Oe, the magnets being positioned such that their magnetic poles are aligned with the rotation axis of the rotor, the magnets being secured to the rotor body by a highly permeable material, each pair of magnets having similar magnetic poles facing each other, and each magnet having a d-axis aligned with the rotor. Aligned longitudinal axis; a plurality of first non-magnetic and non-conductive components are provided in the second slot of the rotor body, each of the first non-magnetic and non-conductive components having a longitudinal axis aligned with the q-axis of the rotor; and a plurality of second non-magnetic and non-conductive components are provided in the third slot of the rotor body near the outer portion of the rotor body, wherein each of the second non-magnetic and non-conductive components has a curved region recessed relative to the surface of the rotor body and an end near the surface of the rotor body, and a magnet is centered relative to the second non-magnetic and non-conductive components such that each magnet is disposed in the curved region.

[0029] According to another example (“Example 22”) that goes further than Example 21, setting the second non-magnetic and non-conductive component includes setting a plurality of smaller radius components and a plurality of larger radius components, the plurality of larger radius components having a larger radius than the smaller radius components, wherein the smaller radius components are set closer to the surface of the rotor than the larger radius components.

[0030] According to another example (“Example 23”) that goes further than Example 21 or 22, setting up the magnets includes setting the magnets adjacent to each other along the rotation axis of the rotor.

[0031] According to another example (“Example 24”) that goes further than any of Examples 21 to 23, one of the pairs of magnets includes a first magnet and a second magnet, such that the first N pole of the first magnet faces the second N pole of the second magnet.

[0032] According to another example (“Example 25”) that goes further than any of Examples 21 to 23, one of the pairs of magnets includes a first magnet and a second magnet, such that the first S pole of the first magnet faces the second S pole of the second magnet.

[0033] According to another example (“Example 26”) that goes further than any of Examples 21 to 25, the magnets and the first non-magnetic and non-conductive components are arranged in an interleaved configuration, wherein each of the first non-magnetic and non-conductive components is disposed between two adjacent magnets in a plurality of pairs of magnets. Attached Figure Description

[0034] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this specification. They illustrate embodiments and, together with the description, serve to explain the principles of this disclosure.

[0035] Figure 1 This is a schematic diagram of the system or motor system disclosed in this article.

[0036] Figures 2A to 2C Cross-sectional views of the rotor in different configurations as explained herein are shown.

[0037] Figures 3A to 3C Explanations are shown separately. Figures 2A to 2C A diagram of the current vector under the maximum torque per ampere (MTPA) condition in the example.

[0038] Figure 4A and Figure 4B It is a graph comparing the current angle and torque values ​​of the internal permanent magnet synchronous motor when the magnetic field is weakened and strengthened.

[0039] Figure 5A and Figure 5B This is a graph showing the magnetic flux density (B) / magnetic field strength (H) curves with different operating points and magnetization states as disclosed herein.

[0040] Figure 6 A graphical representation of the relationship between flux linkage and torque for a series of current vectors is shown.

[0041] Figure 7 A partial view of a cross-section of an electric motor according to an embodiment disclosed herein is shown.

[0042] Figure 8 This is a graph showing the B / H curves with different load lines and recoveries for various magnetization states, as disclosed herein.

[0043] Figure 9A and Figure 9B A graphical representation of the efficiency / torque-speed curves for two different electric motors as disclosed herein is shown.

[0044] Figure 10A It is a graphical representation of the process of changing the magnetic flux of a permanent magnet at various speeds, as disclosed in this article.

[0045] Figure 10B This is a graphical representation of the difference in loss reduction between variable flux motors and non-variable flux permanent magnet motors, as disclosed in this paper.

[0046] Figure 11A A plot of the optimal efficiency of the variable flux machine as disclosed herein is shown.

[0047] Figure 11B It shows the corresponding Figure 11A The optimal efficiency diagram is the magnetization state distribution diagram.

[0048] Figure 12 A partial view of a cross-section of an electric motor according to an embodiment disclosed herein is shown.

[0049] Figure 13 The magnet operating points according to embodiments disclosed herein are shown.

[0050] Figure 14 The input electrical signal for each phase without VF regulation is shown according to an embodiment disclosed herein.

[0051] Figure 15 The input electrical signal for each phase of a timing VF pulse according to an embodiment disclosed herein is shown.

[0052] Figure 16 The ideal output torque for each phase according to the embodiments disclosed herein is shown.

[0053] Figure 17 The ideal total motor output torque according to the embodiments disclosed herein is shown.

[0054] Figure 18A A diagram of a 4-pole, 6-slot winding of a motor according to an embodiment disclosed herein is shown.

[0055] Figure 18B A diagram of a 6-pole, 9-slot winding of a motor according to an embodiment disclosed herein is shown.

[0056] Figure 18C An 8-pole, 9-slot winding diagram of an electric motor according to an embodiment disclosed herein is shown.

[0057] Figure 18D An 8-pole, 12-slot winding diagram of an electric motor according to an embodiment disclosed herein is shown.

[0058] Figure 19 The BH curve of an iron nitride permanent magnet according to an embodiment disclosed herein is shown.

[0059] Figure 20 A flowchart of a process or method for operating a motor according to an embodiment disclosed herein is shown.

[0060] Figure 21 A flowchart of a process or method for operating a motor according to an embodiment disclosed herein is shown.

[0061] Figure 22 A flowchart is shown of a process or method for manufacturing or manufacturing an electric motor rotor according to embodiments disclosed herein. Detailed Implementation

[0062] The present disclosure generally relates to electric machines that do not use any rare earth metals, strategic / critical minerals, non-lanthanide elements or non-cobalt-based materials in their permanent magnets. In various embodiments, non-lanthanide, non-cobalt materials form at least 85% of the mass of the magnet component material. Various concepts also relate to systems or controllers configured to improve the functionality of such electric machines.

[0063] Explanation of Used Terms

[0064] LCF: Low Coercivity (Hci)

[0065] HCF: High Coercivity (Hci)

[0066] PMSM: Permanent Magnet Synchronous Motor

[0067] Ld: Direct-axis Stator Inductance

[0068] Lq: Quadrature-axis Stator Inductance

[0069] Flux Intensification (FI): The condition where Ld>Lq, also referred to as anti-salient pole (configuration) or negative salient pole (configuration)

[0070] Flux Weakening (FW): The condition where Lq>Ld

[0071] Flux Weakening Interior PMSM (FW-IPMSM): A PMSM configuration where Lq>Ld

[0072] Positive Reluctance Torque: A "cogging" torque that is beneficial to the generated torque, which occurs during flux intensification

[0073] Negative Reluctance Torque: A "cogging" torque that counteracts the generated torque, which occurs during flux weakening

[0074] Recoil Permeability (μr): The slope of the B vs. H curve in the operating region

[0075] The positioning of the magnets within the rotor and the design of ribs and bridges in the steel rotor structure determine whether the motor design is flux intensification (FI) or flux weakening (FW). In some examples, the magnets may be a series of magnets laminated together. If the direct-axis inductance (Ld) is less than the quadrature-axis inductance (Lq) or Ld<Lq, the PMSM motor design is considered FW. If the direct-axis inductance (Ld) is greater than the quadrature-axis inductance (Lq), or Ld>Lq, the PMSM motor design is considered FI. Flux intensification (where Ld>Lq) is also referred to as anti-salient pole or negative salient pole.

[0076] Figure 1This is a schematic diagram of a system or motor system 100 as disclosed herein. The system includes a motor 102 (e.g., an electric motor or generator) comprising a rotor 104 and a stator 106, and one or more sensors 108 coupled thereto for measuring parameters associated with the rotor and / or stator (e.g., motor speed or temperature, etc.). Although it should be understood that the rotor 104 may be disposed around the stator 106, in the exemplary system, in a preferred embodiment, the rotor 104 is disposed within the stator 106 (or the stator 106 is disposed around the rotor 104). System 100 also includes a controller 110 operatively coupled to the motor 102, capable of controlling the operation of the motor. Controller 110 may include a processing unit 112 (e.g., a computer processor) and a memory unit 114 coupled to the processing unit. Memory unit 114 may be a non-transitory computer-readable medium storing computer-readable instructions thereon that, when executed by processing unit 112, cause the processing unit to perform any or more of the processes or algorithms further disclosed herein. Processing and / or algorithms can control the operation of a motor based on inputs such as sensor readings.

[0077] Figures 2A to 2C Different examples of how magnets can be arranged in the rotor (rotor topology) of an electric motor (such as in a permanent magnet synchronous motor (PMSM)) are shown. Figure 2A An example of a surface PMSM is shown, in which magnets are arranged around laminations of the rotor core on the outer surface of the rotor. Figure 2B An example of a field weakening (FW) internal PMSM (also referred to herein as FW-IPMSM) is shown, in which magnets are disposed within the core of a rotor, and magnetic barriers are disposed on both sides of each magnet. In some examples, there are two magnetic barriers for each magnet, such that when there are four magnets, there are a total of eight magnetic barriers. Figure 2C An example of a magnetic field enhanced (FI) internal PMSM (also referred to herein as FI-IPMSM) is shown, in which magnets are disposed within the core of the rotor, and magnetic barriers are arranged on the q-axis between adjacent magnets such that there is at least one magnetic barrier between each pair of adjacent magnets. In some examples, there are at least four magnetic barriers when there are four magnets. The number of magnetic barriers can be the same as or a multiple of the number of magnets. Each figure also shows arrows illustrating the d-axis (d) and q-axis (q) and the north and south poles (N and S) associated with the magnets. The d-axis is the direct axis, the axis through which the magnetic flux is generated by the magnetic field windings, and the q-axis is the orthogonal axis, the axis through which torque is generated.

[0078] The natural operation of flux-enhancing (FI) machines favors the use of high Br, low Hci (LCF) magnet materials, such as iron nitride (FeN). FeN LCF magnets help optimize the torque density of battery-operated electric vehicle (BEV) traction motors obtainable from FI machines. During operation, the magnet pushes the load line upward, reducing the likelihood of demagnetization and increasing the air gap flux density, which is proportional to the motor torque. When Ld > Lq, a positive reluctance torque exists, significantly increasing the motor's torque output. In this case, there is another significant increase in motor torque with minimal current input. FI operation may be difficult to perform with high Hci (HCF) magnet materials such as NdFeB due to the presence of a negative reluctance torque, where cogging torque cancels out the generated torque and causes noise and vibration. The higher restoring permeability of FeN (μr = 1.8 to 2.0) further aids FI operation by increasing Ld compared to NdFeB (μr = 1.05 to 1.10).

[0079] FeN LCF magnets can help optimize the torque density of flux-enhanced BEV traction motors by pushing the magnets higher up to the load line and utilizing positive reluctance torque to add to the stator torque. The increased torque density of the FI motor improves the efficiency of the BEV traction motor, although typically at lower speeds. This leads to the use of variable flux (VF) technology to help improve motor efficiency at high-speed, low-torque operating points.

[0080] Variable flux (VF) operation is defined as the ability to dynamically adjust the magnetization of permanent magnets during motor operation. It's analogous to having a knob to select the optimal magnetization level of the magnets to maximize efficiency at any torque and speed operating point on a BEV drive cycle. VF operation is achieved using FeN LCF magnets, which is not possible with NdFeB HCF magnets. The main advantage of VF operation is at high speeds, where the magnetization of the magnets can be reduced to optimize motor efficiency at low torque, high-speed operating points, currently an inherent weakness of BEV traction motors. VF operation is activated by magnetizing the permanent magnets in the rotor and demagnetizing them by pulsing the stator coils with appropriate phase and amplitude of the magnetizing current.

[0081] By employing a suitable VF control scheme, the magnetization of FeN LCF magnets can be varied in a continuous or discrete manner, simulating the magnetic properties of a continuously variable transmission (CVT) and a 5-speed manual transmission in an internal combustion engine (ICE) vehicle. This control scheme is implemented as a digitally programmed lookup table and integrated into the drive electronics controlling the inverter, which supplies current to the three phases of the electric motor. The inherent ease of operation of variable flux (VF) machines favors the use of high Br, low Hci (LCF) magnet materials, such as FeN.

[0082] FeN LCF helps to optimize the adjustability of VF control of electric motors. VF control is generally difficult, if not impossible, to implement with high Hci (HCF) magnet materials such as NdFeB. This is because the magnitude of the current required to magnetize and demagnetize the magnets is usually too large. Compared with NdFeB (μr = 1.05 to 1.10), the higher recoil permeability of FeN (μr = 1.8 to 2.0) also facilitates VF operation by increasing the gain of the magnetization / demagnetization current when adjusting the magnetization of the FeN LCF magnets.

[0083] FeN LCF magnets optimize the efficiency of flux-enhanced BEV traction motors by allowing instantaneous adjustment of rotor flux according to the varying torque / speed operating points of the electric motor. The efficiency improvement of FeN LCF variable flux BEV traction motors applies to full-speed and torque drive cycles, but the maximum and most significant efficiency gain occurs in the higher speed operating range.

[0084] In the examples disclosed herein, Figure 1 the magnets in the electric motor are magnets with low coercivity (Hci), such as iron nitride (FeN) magnets operating as low coercivity (LCF) magnets, and are arranged in Figure 2C the configuration shown, which is also referred to as an anti-salient pole or inverse salient pole configuration, such that Ld>Lq, where Ld is the direct axis (d-axis) stator inductance, and Lq is the quadrature axis (q-axis) stator inductance. For example, each magnet may be disposed on the d-axis of the electric motor, and one or more magnetic barriers may be disposed on the q-axis of the electric motor. In Figure 2A the example shown, Ld is substantially the same as Lq (with little or no magnetic saliency), and in Figure 2B , Ld<Lq (larger magnetic saliency ratio). Figures 3A to 3C respectively show the diagrams of current vectors for the maximum torque per ampere (MTPA) condition in the examples of Figures 2A to 2C , which show the positions of the stator current (I_s) and the associated permanent magnet flux (λpm).

[0085] Another property of iron nitride (FeN) magnets is the mass-volume advantage of the magnets. Based on the volume-to-weight ratio associated with the common magnetic saturation of rare earth magnets and FeN magnets, the FeN magnets have a volume-to-weight ratio (mm³ / grams) of greater than 0.1, or in some examples, greater than 0.2. In some examples, the magnet has a volume-to-weight ratio of 0.1 to 0.15, 0.15 to 0.2, 0.2 to 0.25, 0.25 to 0.3, or any other suitable value within the aforementioned ranges, or any other suitable range between any of the aforementioned ranges, as compared to rare earth magnets having a volume-to-weight ratio of less than 0.07. The volume-to-weight ratio can be calculated by multiplying the thickness of the magnet by the width of the magnet and dividing by the mass of the magnet. Advantageously, a greater volume-to-weight ratio allows the magnet to have a lower density compared to higher magnets. Magnets with lower density have a larger volume, which provides a larger area to facilitate demagnetization or alteration of the variable flux of the magnet. Furthermore, denser magnets typically require more cooling due to generating more heat compared to less dense magnets.

[0086] In a typical FW-IPMSM configuration, to generate positive reluctance torque (which is "cogging" torque, and the "cogging" torque is beneficial for the generated torque), a portion of the stator current distribution is positioned to counteract the permanent magnet magnetic flux, i.e., negative d-axis current (-Id), as Figure 4A shown, where the x-axis represents the angle and the y-axis represents the torque. Figure 4A it is shown that the total torque of Ld<Lq (which is the sum of the permanent magnet torque or PM torque and the reluctance torque) reaches a maximum value in the positive current angle within the field weakening range. Therefore, increasing said portion of the stator current on the negative d-axis reduces the terminal voltage for operation above the base speed, at the cost of increased stator ohmic losses. In the FI-IPMSM configuration, positive reluctance torque is generated when a portion of the stator current distribution is aligned with the positive d-axis (+Id), as Figure 4B shown, where the total torque of Ld>Lq reaches a maximum value at the negative current angle in the field intensifying range. Specifically, positive d-axis current facilitates the use of LCF magnets, as the positive d-axis current reinforces the permanent magnet flux. For example, in the case of FeN magnets, the considerably high magnetic permeability of the FeN magnets placed on the d-axis further increases Ld. The magnetic permeability (μ) of a magnet is calculated by μ=B / H, where B is the magnetic flux density and H is the magnetic field strength (or magnetic field intensity) of the magnet. For FeN magnets, the magnetic permeability (μ) is approximately 1.8 to 2.0. By reducing the positive d-axis current, operation above the base speed is made possible, thereby reducing ohmic losses with this rotor configuration. Reducing Lq also reduces magnetic saturation caused by the load current (Iq).

[0087] The high remanent flux density (Br, also known as remanence) of FeN provides high torque density. To further utilize and contribute to the best use of FeN's low Hci and high Br characteristics, flux enhancement (FI) control techniques can be combined with variable flux (VF) control techniques to enable variable flux enhanced internal permanent magnet synchronous motors (VFI-IPMSMs) for traction motor applications. As described herein, traction motor applications refer to the use of electric motors to drive electric vehicles, such as battery electric vehicles (BEVs) or hybrid electric vehicles (HEVs) as known in the art. Advantageously, with VF control, LCF FeN magnets are more capable of operating with variable magnetomotive force and flux characteristics.

[0088] Figure 5A A graph showing a portion of the B / H curve is presented, where the x-axis represents magnetic field strength or H and the y-axis represents magnetic flux density or B. The graph compares the nominal operating point of a magnet with a current angle of 0 degrees with the operating points of FW-controlled and FI-controlled magnets, showing the alignment of the operating point with the B / H curve.

[0089] Figure 5B Different magnetization states are shown, where each magnetization state (MS) has a different B / H curve represented by different magnetization percentages. For example, the B / H curve of a magnet in a 25% magnetization state has the same slope or permeability (μ) as that of a magnet in a 100% magnetization state, but is positioned along the y-axis at a lower value than that of the 100% magnetization state. In some examples, FeN magnets can be intentionally demagnetized or remagnetized to control the flux linkage and back (or back)electromotive force (EMF) voltage of an electric motor, thereby interacting with, for example... Figure 5A Compared to the magnet operating point shown during FW or FI operation, this allows the traction motor to operate with higher efficiency in the high-speed region of operation, such as... Figure 5B As shown. For example, in Figure 5B In this context, because the MS of the magnet changes with the application of increasing or decreasing the MS-manipulating d-axis current (+Id), the flux linkage of the permanent magnet (PM) is variable, resulting in the MS being between 0% and 100% magnetized at any given time.

[0090] VFI-IPMSM combines the high torque density of permanent magnet motors, the variable flux properties of non-permanent magnet motors, and the benefits of flux enhancement via anti-salient poles (Ld>Lq). Because FeN magnets enable and enhance the design of this motor, all these positive properties combine to allow for competitive cost and performance, with improved total drive cycle efficiency compared to traction motors without rare earth or strategic / critical mineral content.

[0091] Figure 6The diagram illustrates the graphical relationship between flux linkage and torque for a series of current vectors, where the x-axis represents the current angle and the y-axis represents the torque. It shows the increase in the value of the torque curve for a constant current amplitude, resulting in a positive reluctance torque when a positive current angle (also known as flux-enhancing current +Id) is applied. The positive current angle also increases the PM flux linkage, as shown by the topmost curve.

[0092] Figure 7 An electric motor 102 according to an embodiment disclosed herein is shown. The motor 102 includes a rotor 104 and a stator 106. The stator 106 may include laminations 702 (e.g., steel laminations or lamination stacks) and coils of insulated wire 704 inserted into the laminations 702, or any suitable configuration. In some examples, the stator 106 may be suitably implemented with hairpin windings, oil spray, and / or liquid cooling. The rotor 104 includes a plurality of FeN LCF magnets 700 inserted into the laminations 702 and aligned with the d-axis, and a plurality of magnetic barriers 706 located between the magnets 700 and aligned with the q-axis. The rotor 104 is configured to be able to rotate at a speed equal to or greater than 20 kRPM, and to achieve at least 55 kW (continuous) and 100 kW (peak) power, at least 300 Nm of torque, and at least 50 kW / L of power density to meet or exceed the targets set by the USDRIVE Partnership Program 2025 by the U.S. Department of Energy. In some examples, a d-axis flux bypass component 708 (which may be part of a lamination or an insertable component made of a different material from the lamination) may also be present between the two magnetic barriers 706. The shape of one or more magnetic barriers 706 may include, for example, a hemisphere, a trapezoid, an arch, or any other suitable construction known in the art.

[0093] Figure 8 The B / H curve or demagnetization curve for demagnetizing a magnet, as used in the embodiments disclosed herein, is shown, where the x-axis represents the magnetic field strength, or H, and the y-axis represents the magnetic flux density, or B. The restoring permeability represents the slope of the B / H curve in the working or operating region. Thus, the restoring line shows the path to the operating point. The nominal load line and two additional load lines for different configurations of a constant permanent magnet (CPM) are also shown. Flux enhancement (FI) adjusts the magnetic flux by pushing the magnet load line upward, while flux reduction (FW) adjusts the magnetic flux by pulling the magnet load line downward. For example, the CPM can be arranged in series or parallel configurations. The nominal load line is the line that starts from the origin and intersects the B / H curve at the operating point (A). In a series CPM configuration, the load line maintains the same slope as the nominal load line and is shifted to the right to intersect at point A. s It intersects the B / H curve at point A, and in the parallel CPM configuration, the load line is shifted to the left to reach point A. pThe point intersects the B / H curve. In different paths from the operating point, for example via different return lines passing through point D or E (for such paths as indicated by the arrows, see...), Figure 5B The B / H curve can pass through point C. s C and C p (if via point D) or through point F s F and F p (If via point E), where, passing through C s C and C p The curve has a greater value than the curve passing through F. s F and F p The curve shows low magnetization.

[0094] FeN is constructed from compounds of iron and nitrogen ( FeN is derived from iron oxide and ammonia, both of which are readily available commodities. FeN is also distinguished by the low-temperature coefficients of both remanent magnetization (Br) and intrinsic coercivity (Hci). For comparison, Table 1 below shows key performance metrics of FeN with bonded and sintered grades of NdFeB magnets, realizing neodymium as a rare-earth metal. Due to FeN's exceptional temperature stability (very low α and β, which are the temperature coefficients of permanent magnets as shown in the table below) and higher resistivity (meaning that eddy currents do not heat the magnet rapidly at high resistivity), the use of rotor cooling can also be minimized, which can facilitate a simplified manufacturing process by reducing the number of components in the final design of the motor.

[0095] Table 1: Key performance metrics of FeN with NdFeB having bonding and sintering grades

[0096] The benefits of using magnets with low Hci or LCF magnets to achieve VFI-IPMSM operation of motors are explained below.

[0097] Rare-earth magnets, such as neodymium magnets, can maintain a certain level of magnetic strength as the temperature rises, and the magnetic strength gradually decreases with increasing temperature. However, once the temperature rises above a certain threshold, LCF magnets (such as FeN magnets) may experience a sharp drop in magnetic field strength. As the temperature rises above 210 degrees Celsius (e.g., when reaching 220 degrees Celsius), the drastic drop can be, for example, a reduction of at least 70%, at least 80%, or at least 90% in magnetic strength. Therefore, FeN magnets are generally eliminated as candidates for use as voltage-generating current sources to prevent high voltage build-up on the motor housing and to allow the faulty motor to cool to a safe temperature.

[0098] By implementing a FI control design (Ld>Lq) for the motor, the risk of demagnetization during operation can be minimized or mitigated, even when the motor utilizes FeN magnets. For example, FeN magnets are naturally more prone to demagnetization at higher temperatures compared to the more commonly used FW control design (Lq>Ld), thus improving motor reliability. Therefore, VFI-IPMSM operation combines the high torque density of permanent magnet motors, the variable flux properties of non-permanent magnet motors, and the benefits of flux enhancement via the anti-salient poles of Ld>Lq, potentially increasing the overall efficiency of the traction motor by more than 2 percentage points throughout the EV's drive cycle, especially at higher speeds.

[0099] Beyond the advantages offered by significantly reducing the use of rare earth metals and / or strategic / critical minerals from traction motors, traction motors represent a more environmentally friendly, eco-friendly, and economically affordable alternative to the continued use of rare earth metals and / or strategic / critical minerals in motor or EV production. Because FeN magnets enable and enhance the design of such electric motors, all these positive properties can be combined to allow for competitive cost and performance of traction motors without rare earth or strategic metal content, with improved overall drive cycle efficiency across the entire drive cycle speed or torque range.

[0100] The U.S. Department of Energy, in its USDRIVE Partner Program 2025, outlined one of the key requirements for traction motors to be marketable to the public: the ability of a traction motor to maintain high efficiency throughout the drive cycle, targeting a power density greater than 50 kW / L. In conventional PM machines, traction motors with non-adjustable PM flux linkages can present bottlenecks because the high torque demand at low speeds and the high power demand at high speeds create a conflict between high-speed and low-speed operation, resulting in inefficiencies in light-load or high-speed operating regions during their drive cycle.

[0101] Figure 9A and Figure 9B Two representations of the efficiency / torque-speed curves for two different PMSMs are shown, where the x-axis represents speed and the y-axis represents torque / power. Figure 9A The figure shows the efficiency / torque-speed curves of a conventional PMSM using a high coercivity (HCF) magnet with non-adjustable PM flux, where the high efficiency region is only located within a small shaded area below the torque and power curves. This is because the HCF magnet generates excessive flux at high speeds, thus reducing the motor efficiency.

[0102] In comparison, Figure 9BThe efficiency / torque-speed curves of the VFI-IPMSM as disclosed herein are shown. Three regions exist where high efficiency can be achieved: a flux-enhanced region under high torque / low speed operation (such as when driving in large urban areas), a zero-magnetization region under medium torque / speed operation, and a flux-depleted region under low torque / high speed operation (such as when driving on highways). Therefore, compared to conventional paired PMSMs with non-adjustable PM flux linkage, the VFI-IPMSM with FeN magnets can improve the overall efficiency of the vehicle over a wide range of drive cycles and conditions.

[0103] Figure 10A This demonstrates how the VFI-IPMSM can be controlled to allow for higher speed operation by reducing the MS. Figure 10A In the diagram, the x-axis represents speed, and the y-axis represents the voltage or percentage of the magnetization state (MS). During low-speed operation, the induced voltage increases at a higher MS percentage until it reaches the maximum voltage driven by the inverter. When the maximum voltage is detected, the PM flux linkage is adjusted ("reduced") to achieve a lower MS percentage, resulting in a decrease in the induced voltage, at which point the induced voltage increases. Each time the induced voltage reaches its maximum voltage with increasing speed, the MS percentage decreases by a certain level.

[0104] Figure 10B The principle of loss reduction in VFI-IPMSM is illustrated, where the x-axis represents speed. As speed increases, the PM flux linkage remains the same for a conventional PM machine with a non-adjustable PM flux linkage, and the losses experienced by the conventional PM machine (e.g., any amount of eddy current) also increase, while the losses remain the same for a VFI-IPMSM machine as currently disclosed, which can reduce the PM flux linkage with increasing speed. Furthermore, as speed increases, the flux weakens and the current increases in a conventional PM machine, while the currently disclosed VFI-IPMSM machine does not produce this current. Therefore, in view of the above... Figure 10A and Figure 10B The VFI-IPMSM machine can reduce losses and extend high-speed operation by changing the PM flux linkage.

[0105] Figure 11A A graph showing the optimal efficiency of the VFI-IPMSM machine, calculated for experimental design for a 30kW vehicle category, is presented. The graph demonstrates a consistent high efficiency of 93% or greater from 0 rpm to 14,000 rpm. Figure 11B It shows the corresponding Figure 11A The MS distribution plot of the optimal efficiency plot. Based on... Figure 11BTypically, a higher MS percentage is used for higher torque / lower speed operation, and a lower MS percentage is used for lower torque / higher speed operation. With the same motor size and rated power (peak power 80kW), the VFI-IPMSM machine's new European drive cycle (NEDC) efficiency is calculated to be 95.3%, compared to 93.1% for a baseline or conventional PM machine with non-adjustable PM flux, resulting in an efficiency increase of more than 2% and a reduction in total drive cycle losses of approximately 20%. Therefore, the VFI-IPMSM machine offers a wider speed range and improved motor efficiency (and battery life) throughout the drive cycle, especially at highway speeds.

[0106] Furthermore, the low Hci value of FeN magnets allows FeN magnets to, as Figure 8 The flux enhancement (FI) is achieved by “pushing upwards” along the load line, as shown, which is the opposite of the flux reduction (FW) caused by “pulling downwards” along the load line with higher Hci or HCF magnets. Conversely, high permeability (μ) also enhances flux by allowing the FeN magnet to “push upwards” along the load line, unlike the flux reduction caused by higher Hci or HCF magnets. Flux enhancement advantageously produces higher efficiency at high operating speeds compared to flux reduction, thus providing higher overall efficiency across the entire range of motor speed and torque operation. The excellent thermal properties of FeN also advantageously enhance the machine's stability over a wide range of operating temperatures. Because machine characteristics depend on magnet characteristics, machine performance will change accordingly if magnet characteristics change significantly with respect to temperature. Furthermore, the low conductivity advantageously minimizes eddy current losses in the FeN magnet, further improving machine efficiency.

[0107] In some examples, the advantages of using flux enhancement may include, but are not limited to, the ability to obtain more torque from the same motor and / or maintain the same amount of torque while reducing the size of the motor. The baseline motor may include FeN permanent magnets, the identification properties of which are shown in Table 2 below.

[0108] Table 2: Properties of baseline FeN magnets

[0109] According to an embodiment, a baseline FeN magnet is implemented together with multiple magnetic barriers in a manner such as... Figure 12 The rotor of the motor shown. Figure 12An electric motor 102 according to an alternative embodiment disclosed herein is shown. The motor includes a rotor 104 and a stator 106. The stator 106 may include laminations of any suitable construction (e.g., steel laminations) and insulated wire coils, such as windings 704, inserted into the laminations. The laminations may be made of a highly permeable material (e.g., steel). In some examples, the stator may be suitably implemented with hairpin windings, oil spray, and / or liquid cooling.

[0110] The rotor 104 includes a plurality of FeN LCF magnets 700 inserted into laminations for alignment with the d-axis and a plurality of magnetic barriers. The magnetic barriers are made of non-magnetic and non-conductive materials (e.g., plastic, resin, air, and / or vacuum) and are located between the magnets and aligned with the q-axis. The magnetic barriers are also referred to herein, for example, as a first non-magnetic, non-conductive component 1202 and a second non-magnetic, non-conductive component 1204, as... Figure 12 As shown. Magnets 700 have pairs of similar magnetic poles facing each other. Thus, in a spoke configuration, N poles 1206 face each other (e.g., such that the first N pole of the first magnet faces the second N pole of the second magnet in the pair), or S poles 1208 face each other (e.g., such that the first S pole of the first magnet faces the second S pole of the second magnet in the pair), wherein the magnet placement is located near the outer surface region of the rotor.

[0111] The rotor 104 may have two (2), four (4), six (6), eight (8), ten (10), twelve (12) or more pairs of magnets. In some examples, it is preferred that the magnetic barriers have a concave and curved configuration. The magnetic barriers may be curved or segmented to represent curves and may be inherently concave (curved inward). In some embodiments, the magnetic barriers may be concave curved magnetic barriers, and the system may include one or more concave magnetic barriers. In some examples, the smallest radius magnetic barrier is closest to the rotor surface (e.g., the outer surface of the rotor), and the largest radius magnetic barrier may be furthest from the rotor surface. In some examples, the origin points of one or more concave magnetic barriers are collinear, the line leading to the center of the FeN LCF magnet. In some examples, the FeN LCF magnets are positioned around the rotor in a spoke configuration. In some examples, the magnetic barriers extend between each magnet.

[0112] In some configurations, rotor 104 is capable of rotating at a speed equal to or greater than 20 kRPM, and achieving a power output of at least 55 kW (continuous) and 100 kW (peak), a torque of at least 300 Nm, and a power density of at least 50 kW / L, to meet or exceed the targets set by the USDRIVE Partnership Program 2025 by the U.S. Department of Energy. In some examples, a d-axis flux bypass component (which may be part of a lamination or an insertable component made of a different material than the lamination) may also be present between the two magnetic barriers. The shape of one or more magnetic barriers may include, for example, a hemisphere, trapezoid, arch, or any other suitable configuration known in the art.

[0113] Rotor 104 includes multiple pairs of magnets 700 (in) Figure 12 As shown, the rotor has four pairs of magnets, which are disposed in the rotor near the outer portion 1210 of the rotor. The magnets 700 have a coercivity (Hci) of 2,000 Oe to 4,000 Oe. The coercivity of the magnet includes any range of values ​​from 2,000 Oe to 2,100 Oe, from 2,100 Oe to 2,200 Oe, from 2,200 Oe to 2,300 Oe, from 2,300 Oe to 2,400 Oe, from 2,400 Oe to 2,500 Oe, from 2,500 Oe to 2,700 Oe, from 2,700 Oe to 3,000 Oe, from 3,000 Oe to 3,200 Oe, from 3,200 Oe to 3,500 Oe, from 3,500 Oe to 3,700 Oe, from 3,700 Oe to 4,000 Oe, or any other suitable value within the aforementioned ranges. The magnet 700 is positioned such that the magnetic poles (e.g., magnetic poles 1206 and 1208) are aligned with the axis of rotation of the rotor 104. Magnets 700 are fixed to rotor 104 by a highly permeable magnetic material. Each pair of magnets 700 has similar magnetic poles facing each other (as shown by the positions of N pole 1206 and S pole 1208). Each magnet 700 has a longitudinal axis 1212 aligned with the d-axis of the rotor.

[0114] The rotor also includes a plurality of first non-magnetic and non-conductive components disposed within the rotor. Each of the first non-magnetic and non-conductive components has a longitudinal axis aligned with the q-axis of the rotor 104. The rotor 104 also includes a plurality of second non-magnetic and non-conductive components 1204 disposed within the rotor 104 near an outer portion 1210 of the rotor 104. Each of the second non-magnetic and non-conductive components 1204 has a curved region 1214 that can be recessed relative to a surface 1216 of the rotor (such as the outer surface 1216 of the rotor) and an end 1218 near the surface 1216 of the rotor 104. Magnets 700 are centered relative to the second non-magnetic and non-conductive components 1204, such that each magnet 700 is disposed in the curved region 1214.

[0115] In some examples, the second non-magnetic and non-conductive component 1204 includes a smaller radius component 1204A and a larger radius component 1204B having a larger radius than the smaller radius component 1204A. The smaller radius component 1204A is positioned closer to the outer surface 1216 of the rotor 104 than the larger radius component 1204B. In some examples, any suitable number of second non-magnetic and non-conductive components 1204 may be present for each magnet 700. For example, Figure 12 Two (2) components are shown (a component with a smaller radius closer to the outer surface of the rotor and a component with a larger radius further away from the outer surface), but it should be understood that, as needed, there may be three (3), four (4), five (5), or any larger number of components with different radii, each component being recessed relative to the outer surface 1216. The individual components may be substantially parallel to each other such that the smaller radius component 1204A does not overlap with the larger radius component 1204B.

[0116] In some examples, the rotor surface 1216 has a plurality of recesses 1220 adjacent to the magnets 700. The recesses 1220 may define a non-circular cross-section of the rotor 104. In some examples, the magnets 700 are arranged adjacent to each other or side-by-side relative to each other. In some examples, each of the magnets 700 has a volume-to-weight ratio greater than 0.1, greater than 0.15, greater than 0.2, or any other suitable value within the aforementioned ranges or any other suitable range between any of the aforementioned ranges. The magnets 700 and the first non-magnetic and non-conductive components 1202 are arranged in an interleaved configuration, wherein each first non-magnetic and non-conductive component 1202 is disposed between two adjacent magnets 700.

[0117] The rotor 104 may be substantially cylindrical, or may include non-circular portions along its surface to have a non-circular cross-sectional surface. One of the magnet 700 and the second non-magnetic, non-conductive component 1204 may also be formed in a manner similar to the Hick alphabet. psi The construction of (“ψ”) is such that the longitudinal axis of the magnet is centered relative to the curved region 1214 of the second non-magnetic and non-conductive component, which is recessed relative to the surface 1216 of the rotor. Each of the magnet 700 and the first non-magnetic and non-conductive component 1202 has a longitudinal axis 1222 and a lateral distance, labeled “T”, which is measured perpendicular to the longitudinal axis 1222. In some examples, the lateral distance T of the magnet 700 or the first non-magnetic and non-conductive component 1202 may be consistent along the longitudinal axis 1222, or the lateral distance T may vary, such as measuring a longer distance T near the outer portion 1210 of the rotor and a shorter distance T near the inner portion 1224 of the rotor, and vice versa (i.e., shorter near the outer portion 1210 and longer near the inner portion 1224).

[0118] In some examples, rotor 104 includes a rotor body 1226 having a plurality of slots 1228, 1230, 1232, and different components of rotor 104 may be disposed in the plurality of slots 1228, 1230, 1232. Rotor body 1226 may include a plurality of laminations (such as...) constructed for stacking. Figure 7 (Laminator 702). The shape and size of the slots can be set to adapt to the shape and size of the corresponding components. A first slot 1228 can be formed in the rotor body 1226 to accommodate the magnet 700. A second slot 1230 can be formed in the rotor body 1226 to accommodate the first non-magnetic and non-conductive component 1202. A third slot 1232 can be formed in the rotor body 1226 to accommodate the second non-magnetic and non-conductive component 1204.

[0119] Figure 13 The operating point of the magnet is shown, or more specifically, the location on the load line for routine operation using the identified permanent magnet is shown. The location on the load line for routine operation is determined by presenting the routine load line current waveform for operating the motor and comparing the NdFeB FW construction with the FeN FI B / H construction; defining the region on the load line for flux reduction operation; and presenting the flux reduction load line current waveforms at three locations on the load line. Figure 13 As shown, the FW operation pulls the magnet downwards along the load line, increasing the risk of irreversible demagnetization. The FW operation is achieved by injecting current into the d-axis during high-speed operation to reduce the magnetic flux. This d-axis current is determined according to... It increases power loss, where P is power, I is current, and R is resistance, and also reduces the efficiency of the motor at high speeds.

[0120] Tables 3A to 3C below compare the specifications, materials, operating parameters, losses, and efficiencies at the point of load of a known NdFeB FW-IPM motor (motor A) and a currently disclosed FeN VFI-IPM motor (motor B).

[0121] Table 3A: Comparison of Motor Specifications

[0122] Table 3B: Comparison of materials and physical properties of electric motors

[0123] Table 3C: Comparison of losses and efficiency at the point of load and at ambient temperature

[0124] According to Table 3A, the two motors have the same physical dimensions and operating specifications. According to Table 3B, although the two motors have similar magnet masses, motor B's magnet has a larger volume-to-weight ratio (approximately 0.2) than motor A's (approximately 0.07). According to Table 3C, when operating at a high-speed / low-torque load point, motor B is 2.5% more efficient than motor A within the same temperature range.

[0125] FeN LCF optimizes the torque density of flux-enhanced BEV traction motors by pushing the magnets higher up the load line and utilizing positive reluctance torque to increase stator torque. The increased torque density of the FI motor improves the efficiency of the BEV traction motor, but primarily within the lower speed operating range. This necessitates the use of variable flux (VF) technology to improve motor efficiency at high-speed, low-torque operating points.

[0126] Variable flux (VF) operation is defined as the ability to dynamically adjust the magnetization of a permanent magnet during motor operation. It is analogous to having a knob to select the optimal magnetization level of the magnet to maximize efficiency at any torque and speed operating point on a BEV drive cycle. VF operation is achieved using FeN LCF magnets, and it is not possible to achieve VF operation using NdFeB HCF magnets.

[0127] The main advantage of VF operation is that at high speeds, the magnetization of the magnets can be reduced to optimize the efficiency of the motor at low torque, high-speed operating points, which is currently an inherent weakness of BEV traction motors. VF operation is activated by magnetizing and demagnetizing the permanent magnets in the rotor by pulsing the stator coils with appropriate phase and amplitude magnetizing current.

[0128] Regarding a suitable VF control scheme Figures 14 to 17 The magnetization of FeN LCF magnets can be varied in a continuous or discrete manner for magnetic simulation of continuously variable transmissions (CVTs) and 5-speed manual transmissions in internal combustion engine (ICE) vehicles. For example, Figures 14 to 17 Different torque curves are shown, illustrating the relationship between electrical angle and torque as explained herein. The relationship between electrical angle and mechanical angle is expressed by the following formula: θe = (P / 2)θm, where θe is the electrical angle (the angular displacement of the rotor relative to the stator's magnetic field), P is the number of poles in the rotor (such that P / 2 is the number of pole pairs), and θm is the mechanical angle (the angular displacement of the rotor's physical / mechanical angle). For example, in the case of a rotor with 24 poles, there are 12 pole pairs, and 30 mechanical degrees for each rotation.

[0129] exist Figure 14 The figure shows the torque curve of a brushless DC motor, where an electrical signal is input to each phase without VF regulation.

[0130] exist Figure 15 In this configuration, an input electrical signal is applied to each phase, timed and aligned with a VF pulse signal (shown as A, B, and C), for synchronization. The VF pulse signal comprises two consecutive positive pulse signals (A and B) separated by 360 / n units, where n is the number of phases in the motor, such as 0 units and 120 units as shown in a three-phase motor. The VF pulse signal also includes a negative pulse signal (C) appearing at the midpoint between the two consecutive positive pulse signals, such as at 60 units as shown in a three-phase motor. The polarity and amplitude can depend on the desired target magnetization level.

[0131] exist Figure 16 The figure shows the torque curve of the brushless DC motor and the ideal output torque of each phase.

[0132] exist Figure 17 The figure shows the ideal total motor output torque, with the goal of minimizing torque disturbances caused by VF current pulses. This figure illustrates the effective torque ripple in a 3-phase 2-pole brushless motor.

[0133] Figures 18A to 18D Different stator winding configurations as disclosed herein are shown to achieve VF operation. Figure 18A The diagram shows a 4-pole, 6-slot winding. Figure 18B The diagram shows a 6-pole, 9-slot winding. Figure 18C The diagram of an 8-pole, 9-slot winding is shown, and Figure 18D An 8-pole, 12-slot winding diagram is shown. Other types of windings can be implemented as appropriate. Using this winding diagram in conjunction with VF operation improves the efficiency of motors using FeN LCF magnets when operation is switching between two different speeds. For example, conventionally performing flux reduction operation on LCF AlNiCo magnets is problematic due to the risk of demagnetizing the magnets in an undesirable manner. The operating point is located along the load line (e.g., Figure 5A The weight of the magnets required for the motor design (as shown) determines the amount of magnets that can be used to generate loads (such as at high speeds and low torque operating points).

[0134] Figure 19 This diagram shows a portion of the hysteresis loop, including the BH curve, when an external magnetic field (x-axis) is applied to an FeN magnet, resulting in magnetization (y-axis). As shown, the FeN magnet has a magnetization slightly above 10,000 Gauss when no magnetic field is applied, and is demagnetized (to 0 Gauss) when a magnetic field of approximately 2,100 Oe is applied in the opposite direction. The loop illustrates the initial and return curves.

[0135] Figure 20A process or method 2000 for operating a rotor or motor as disclosed herein is illustrated. Method 2000 includes a step 2002 of receiving a torque command. The torque command may be, for example... Figure 1 The controller 110 shown is operatively connected to the rotor 104. In step 2004, a flux-enhancing operation is performed by operating the rotor to generate a positive reluctance torque and align the stator current distribution with the positive d-axis of the rotor, such that the total torque reaches its maximum value at a negative current angle within the range of the rotor's flux-enhancing operation, wherein the inductance on the rotor's d-axis is greater than the inductance on the rotor's q-axis (Ld>Lq).

[0136] Figure 21 A process or method 2100 for operating a rotor or motor as disclosed herein is illustrated. Method 2100 includes a step 2102 of receiving a torque command and a speed command. The torque command and speed command can be, for example, as... Figure 1 The controller 110 shown receives the rotor 104 and is operatively coupled to it. In step 2104, the rotor's operating type is determined based on torque and speed commands. The operating type can be selected from one of the following: high torque / low speed operation 2104A, where the rotor operates in the flux-enhancing region of the current angle; medium torque / speed operation 2104B, where the rotor operates in the zero magnetization region of the current angle; and low torque / high speed operation 2104C, where the rotor operates in the flux-decrease region of the current angle. The operating type can be changed or adjusted during motor operation such that, as torque and / or speed change, the operating type is appropriately changed or newly selected according to the new torque and / or speed commands. In step 2106, the rotor is operated by applying current to it according to the determined operating type. The rotor includes multiple pairs of magnets disposed near the exterior of the rotor. The magnets have a coercivity of 2,000 Oe to 4,000 Oe. The magnets are positioned such that the magnetic poles are aligned with the rotation axis of the rotor. Each pair of magnets has similar magnetic poles facing each other, and each magnet has a longitudinal axis aligned with the d-axis of the rotor.

[0137] In operation types 2104A, 2104B, and 2104C, the specific values ​​for determining whether the rotor operates at high torque / low speed, medium range, or low torque / high speed can vary.

[0138] In some examples, a torque command may be interpreted as “high torque” if the value of the torque to be achieved is at least 60%, at least 70%, at least 80%, or any other suitable value within the aforementioned range or any other suitable range between the aforementioned ranges, relative to the maximum (or peak) torque that can be safely and reliably delivered by the rotor. For example, if the rotor can safely deliver a maximum torque of up to 500 Nm, the high torque region may be interpreted as at least 300 Nm, at least 350 Nm, or at least 400 Nm.

[0139] In some examples, a torque command can be interpreted as “low torque” if the desired torque value is no greater than 30%, 20%, 10%, or any other suitable value within or between the aforementioned ranges relative to the maximum (or peak) torque. For example, if the maximum torque is 500 Nm, the low torque range can be interpreted as no greater than 150 Nm, 100 Nm, or 50 Nm. Therefore, as described above, a medium torque range can be a value between two regions of high and low torque values.

[0140] Similarly, in some examples, a speed command can be interpreted as “high speed” if the value of the speed to be achieved is at least 60%, at least 70%, at least 80%, or any other suitable value or any other suitable range between the aforementioned ranges relative to the maximum (or peak) speed value that can be safely and reliably achieved by the rotor. For example, if the rotor can operate safely at a maximum speed of up to 20 kRPM, the high-speed region can be interpreted as at least 12 kRPM, at least 14 kRPM, or at least 16 kRPM.

[0141] In some examples, a speed command can be interpreted as “low speed” if the desired speed value is no greater than 30%, 20%, 10%, or any other suitable value within or between the aforementioned ranges relative to the maximum (or peak) speed value. For example, if the maximum speed is 20 kRPM, the low speed range can be interpreted as no greater than 6 kRPM, 4 kRPM, or 2 kRPM. Therefore, a medium speed range can be a speed value between two regions of high and low speed values, as described above. It should be understood that the maximum values ​​for torque and speed described above can be provided by the manufacturer as part of the rotor's original specifications. Alternatively, the maximum values ​​can be determined experimentally.

[0142] In light of the above, according to some examples, in high torque / low speed operation 2104A, the rotor is operated to provide a torque of at least 60% of the rotor's maximum torque and a speed of no more than 30% of the rotor's maximum speed. In some examples, in medium torque / speed operation 2104B, the rotor is operated to provide a torque between 30% and 60% of the rotor's maximum torque and a speed between 30% and 60% of the rotor's maximum speed. In some examples, in low torque / high speed operation 2104C, the rotor is operated to provide a torque of no more than 30% of the rotor's maximum torque and a speed of at least 60% of the rotor's maximum speed.

[0143] Figure 22A process or method 2200 for manufacturing or producing a rotor of an electric motor as disclosed herein is illustrated. Method 2200 includes a step 2202 of providing a rotor body comprising a plurality of laminations constructed for stacking. The rotor body has a plurality of first slots, a plurality of second slots, and a plurality of third slots. In step 2204, a plurality of pairs of magnets are disposed in the first slots of the rotor body near an external portion of the rotor body. For example, the magnets have a coercivity of 2,000 Oe to 4,000 Oe, the magnets are positioned such that their poles are aligned with the rotational axis of the rotor, the magnets are fixed to the rotor body by a highly permeable material, each pair of magnets has similar poles facing each other, and each magnet has a longitudinal axis aligned with the d-axis of the rotor. In step 2206, a plurality of first nonmagnetic and nonconductive components are disposed in the second slots of the rotor body. For example, each of the first nonmagnetic and nonconductive components has a longitudinal axis aligned with the q-axis of the rotor. In step 2208, a plurality of second nonmagnetic and nonconductive components are disposed in the third slots of the rotor body near an external portion of the rotor body. For example, each of the second non-magnetic and non-conductive components has a curved region recessed relative to the surface of the rotor body and an end near the surface of the rotor body, and the magnet is centered relative to the second non-magnetic and non-conductive component, such that each of the magnets is disposed in the curved region.

[0144] Numerous features and advantages, including various alternatives and details of the structure and function of the devices and / or methods, have been set forth in the foregoing description. Furthermore, the scope of the various concepts addressed in this disclosure has been described generally and with respect to specific examples. This disclosure is intended to be illustrative only and is not intended to be exhaustive. It will be apparent to those skilled in the art that various modifications can be made, particularly in terms of structure, materials, elements, components, shapes, dimensions, and the arrangement of components in combinations incorporating the principles of this disclosure, to the full extent indicated by the broad general meaning of the terms expressing the appended claims. Such various modifications are intended to be covered therein without departing from the spirit and scope of the appended claims.

Claims

1. A rotor for an electric motor, the rotor comprising: Multiple pairs of magnets are disposed in the rotor near the outer portion of the rotor, wherein: The magnet has a coercivity (Hci) of 2,000 Oe to 4,000 Oe; the magnet is positioned such that the magnetic poles are aligned with the rotation axis of the rotor; the magnet is fixed to the rotor by a highly permeable material; each pair of magnets has similar magnetic poles facing each other; and each of the magnets has a longitudinal axis aligned with the d-axis of the rotor. A plurality of first non-magnetic and non-conductive components are disposed in the rotor, wherein each of the first non-magnetic and non-conductive components has a longitudinal axis aligned with the q-axis of the rotor; and A plurality of second non-magnetic and non-conductive components are disposed in the rotor near the outer portion of the rotor, wherein: Each of the second non-magnetic and non-conductive components has a curved region recessed relative to the surface of the rotor and an end near the surface of the rotor; and The magnet is centered relative to the second non-magnetic and non-conductive component, such that each of the magnets is positioned in the curved region.

2. The rotor according to claim 1, wherein, The second non-magnetic and non-conductive component includes a smaller radius component and a larger radius component, wherein the larger radius component has a larger radius than the smaller radius component, and the smaller radius component is positioned closer to the surface of the rotor than the larger radius component.

3. The rotor according to claim 1 or 2, wherein, The surface of the rotor has a plurality of recessed portions that approximate the magnet.

4. The rotor according to any one of claims 1 to 3, wherein, The magnets are arranged adjacent to each other along the rotation axis of the rotor.

5. The rotor according to any one of claims 1 to 4, wherein, Each of the magnets has a volume-to-weight ratio greater than 0.

1.

6. The rotor according to any one of claims 1 to 5, wherein, Each of the magnets has a permeability ranging from 1.8 to 2.

0.

7. The rotor according to any one of claims 1 to 6, wherein, The magnet includes an iron nitride (FeN) magnet.

8. The rotor according to any one of claims 1 to 7, wherein, One of the multiple pairs of magnets includes a first magnet and a second magnet, such that the first N pole of the first magnet faces the second N pole of the second magnet.

9. The rotor according to any one of claims 1 to 7, wherein, One of the multiple pairs of magnets includes a first magnet and a second magnet, such that the first S pole of the first magnet faces the second S pole of the second magnet.

10. The rotor according to any one of claims 1 to 9, wherein, Each of the first non-magnetic and non-conductive components has a lateral distance measured perpendicular to the longitudinal axis of the first non-magnetic and non-conductive component, and the lateral distances measured along the longitudinal axis of the first non-magnetic and non-conductive component are consistent.

11. The rotor according to any one of claims 1 to 9, wherein, Each of the first non-magnetic and non-conductive components has a lateral distance measured perpendicular to the longitudinal axis of the first non-magnetic and non-conductive component, and the lateral distance varies along the longitudinal axis of the first non-magnetic and non-conductive component such that the lateral distance measured near the outer portion of the rotor is longer than the lateral distance measured near the inner portion of the rotor.

12. The rotor according to any one of claims 1 to 9, wherein, Each of the first non-magnetic and non-conductive components has a lateral distance measured perpendicular to the longitudinal axis of the first non-magnetic and non-conductive component, and the lateral distance varies along the longitudinal axis of the first non-magnetic and non-conductive component such that the lateral distance measured near the outer portion of the rotor is shorter than the lateral distance measured near the inner portion of the rotor.

13. The rotor according to any one of claims 1 to 12, wherein, One or more of the first non-magnetic and non-conductive component and the second non-magnetic and non-conductive component are made of plastic or resin.

14. The rotor according to any one of claims 1 to 13, wherein, The magnets and the first non-magnetic and non-conductive components are arranged in an alternating configuration, wherein each of the first non-magnetic and non-conductive components is disposed between two adjacent magnets in the plurality of pairs of magnets.

15. An electric motor, the electric motor comprising: stator; as well as The rotor is a rotor according to any one of claims 1 to 14, and the rotor is disposed in the stator.

16. A method of operating an electric motor, the electric motor having a rotor according to any one of claims 1 to 14, the method comprising: The torque command is received by a controller that is operatively connected to the rotor; as well as The controller performs a flux enhancement operation by operating the rotor based on the torque command to generate a positive reluctance torque, and aligns the current distribution of the stator with the positive d-axis of the rotor, such that the total torque reaches its maximum value at a negative current angle within the range of the rotor's magnetic field enhancement operation, wherein the inductance on the d-axis of the rotor is greater than the inductance on the q-axis of the rotor.

17. A method of operating a rotor, the method comprising: Torque and speed commands are received by a controller that is connected to the rotor operating ground; The controller determines the rotor's operation type based on the torque command and the speed command, the operation type being selected from one of the following: a) High torque / low speed operation, wherein the rotor operates in the flux enhancement region of the current angle. b) Medium-range torque / speed operation, wherein the rotor operates in the zero-magnetization region of the current angle, and c) Low torque / high speed operation, wherein the rotor operates in the flux reduction region of the current angle; and The rotor is operated by applying current to it according to a determined operation type. The rotor includes multiple pairs of magnets disposed in the rotor near the outer portion of the rotor, wherein the magnets have a coercivity (Hci) of 2,000 Oe to 4,000 Oe, the magnets are positioned such that their magnetic poles are aligned with the rotational axis of the rotor, each of the magnets has similar magnetic poles facing each other, and each of the magnets has a longitudinal axis aligned with the d-axis of the rotor.

18. The method according to claim 17, wherein, In the high torque / low speed operation, the rotor is operated to provide a torque that is at least 60% of the rotor's maximum torque and a speed that is no more than 30% of the rotor's maximum speed.

19. The method according to claim 17, wherein, In the medium torque / speed operation, the rotor is operated to provide torque between 30% and 60% of the rotor's maximum torque and speed between 30% and 60% of the rotor's maximum speed.

20. The method of claim 17, wherein, In the low torque / high speed operation, the rotor is operated to provide a torque not exceeding 30% of the rotor's maximum torque and a speed of at least 60% of the rotor's maximum speed.

21. A method for manufacturing a rotor of an electric motor, the method comprising: A rotor body is provided, the rotor body comprising a plurality of laminations constructed for stacking, the rotor body having a plurality of first slots, a plurality of second slots and a plurality of third slots; Multiple pairs of magnets are disposed in the first slot of the rotor body near the outer portion of the rotor body, wherein the magnets have a coercivity (Hci) of 2,000 Oe to 4,000 Oe, the magnets are positioned such that the magnetic poles are aligned with the rotation axis of the rotor, the magnets are fixed to the rotor body by a highly permeable material, each pair of magnets has similar magnetic poles facing each other, and each of the magnets has a longitudinal axis aligned with the d-axis of the rotor; A plurality of first non-magnetic and non-conductive components are disposed in the second slot of the rotor body, each of the first non-magnetic and non-conductive components having a longitudinal axis aligned with the q-axis of the rotor; and In the third groove of the rotor body, a plurality of second non-magnetic and non-conductive components are disposed near the outer portion of the rotor body, wherein each of the second non-magnetic and non-conductive components has a curved region recessed relative to the surface of the rotor body and an end near the surface of the rotor body, and the magnet is centered relative to the second non-magnetic and non-conductive components, such that each of the magnets is disposed in the curved region.

22. The method according to claim 21, wherein, The step of setting the second non-magnetic and non-conductive component includes: setting a plurality of smaller radius components and a plurality of larger radius components, wherein the larger radius components have a larger radius than the smaller radius components, and the smaller radius components are set closer to the surface of the rotor than the larger radius components.

23. The method according to claim 21 or 22, wherein, The step of setting up the magnets includes: setting the magnets adjacent to each other along the rotation axis of the rotor.

24. The method according to any one of claims 21 to 23, wherein, One of the multiple pairs of magnets includes a first magnet and a second magnet, such that the first N pole of the first magnet faces the second N pole of the second magnet.

25. The method according to any one of claims 21 to 23, wherein, One of the multiple pairs of magnets includes a first magnet and a second magnet, such that the first S pole of the first magnet faces the second S pole of the second magnet.

26. The method according to any one of claims 21 to 25, wherein, The magnets and the first non-magnetic and non-conductive components are arranged in an alternating configuration, wherein each of the first non-magnetic and non-conductive components is disposed between two adjacent magnets in the plurality of pairs of magnets.

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