Electric motor with hybrid magnet rotor comprising similar magnet blocks

Abstract

A permanent magnet rotor assembly for an electric motor, an electric vehicle, and a method are provided. The assembly includes an annular stack of rotor lamination layers ("rotor laminations") constructed from a magnetic core material. The rotor laminations have inboard axial surfaces that collectively define a set of first openings through the magnetic core material and a set of second openings through the magnetic core material. The annular stack includes a first arrangement of permanent magnets and a second arrangement of permanent magnets.

Description

Technical Field

[0001] This disclosure relates to rotors for electric motors, and more specifically, to electric motors having an arrangement of hybrid magnets. Background Technology

[0002] Rotary motors of the type used in electric drive systems of electric vehicles operate in electric mode and / or generator mode. In electric mode, output torque is delivered to a coupled load (e.g., one or more wheels of a motor vehicle), and in generator mode, the machine rotates to generate electricity. In a typical configuration, the motor comprises a cylindrical rotor formed of annular stacks of thin magnetic rotor laminations, or "rotor lamps." The magnetic material of the rotor laminations is typically an alloy of iron and silicon, commonly referred to in the art as electrical steel.

[0003] Permanent magnets can include, for example, neodymium (Nd) magnets, also known as NdFeB, NIB, or Neo magnets. Nd magnets are rare-earth magnets made of an alloy of neodymium (Nd), iron (Fe), and / or boron (B). Nd magnets have high coercivity (i.e., resistance to demagnetization) and high magnetic energy density. Permanent magnets can be disposed within openings or slots in the rotor to generate motor flux with a magnetic flux field following a predefined path, which can be enhanced and / or suppressed. Enhancing the magnetic flux field increases the motor's torque production, while suppressing the magnetic flux field limits the motor's torque production. The configuration and / or topology of the permanent magnets disposed within the rotor can determine the motor's power density.

[0004] While current rotors for electric motors have achieved their intended purpose, new and improved arrangements of permanent magnets within the rotor are still needed to provide increased torque generation and power density within the motor. Summary of the Invention

[0005] According to several aspects of this disclosure, a permanent magnet rotor assembly for an electric motor is provided. The permanent magnet rotor assembly includes an annular stack of rotor laminations (“rotor laminations”) constructed of a core material. The rotor laminations have inner axial surfaces that collectively define a set of first openings through the core material and a set of second openings through the core material. The annular stack includes a first arrangement and a second arrangement of permanent magnets. Each corresponding permanent magnet in the first arrangement is disposed within a corresponding first opening in the set of first openings, and the first arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets. Each corresponding permanent magnet in the second arrangement is disposed within a corresponding second opening in the set of second openings, and the second arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets.

[0006] According to another aspect of this disclosure, the at least two highly coercive magnets include at least one of neodymium-based magnets or samarium-cobalt magnets.

[0007] According to another aspect of this disclosure, the at least one low coercivity magnet comprises a ferrite-based magnet.

[0008] According to another aspect of this disclosure, the highly coercive magnet has parallel magnetization.

[0009] According to another aspect of this disclosure, the highly coercive magnet is segmented.

[0010] According to another aspect of this disclosure, the at least one low coercivity magnet is curved and has radial magnetization.

[0011] According to another aspect of this disclosure, at least one of the highly coercive magnets is substantially parallel to the radius of the magnetic pole.

[0012] According to another aspect of this disclosure, the inner layer of the at least one low coercivity magnet has a V-shaped structure.

[0013] According to another aspect of this disclosure, the two low coercivity magnets are separated by a central column.

[0014] According to another aspect of this disclosure, the size of the high coercivity magnet is different from that of the low coercivity magnet, and each magnetic pole includes only two magnet sizes.

[0015] According to another aspect of this disclosure, a first arrangement of permanent magnets includes two low coercivity magnets, and a second arrangement of permanent magnets includes one low coercivity magnet.

[0016] According to several aspects of this disclosure, an electric vehicle is provided. The electric vehicle includes an electric drive system having an electric motor, the electric motor including a stator and a permanent magnet rotor assembly for the electric motor, the permanent magnet rotor assembly being configured to rotate due to a rotating magnetic field created by the stator. The permanent magnet rotor assembly includes an annular stack of rotor laminations (“rotor laminations”) constructed of a core material. The rotor laminations have inner axial surfaces that collectively define a set of first openings through the core material and a set of second openings through the core material, wherein the annular stack includes at least one magnetic pole. Each corresponding permanent magnet of a first arrangement is disposed within a corresponding first opening in the set of first openings, and the first arrangement of the permanent magnets is arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets. Each of the corresponding permanent magnets in the second arrangement is disposed in a corresponding second opening in the group of second openings, and the second arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low coercivity magnet surrounded by at least two high coercivity magnets.

[0017] According to another aspect of this disclosure, the at least one high coercivity magnet includes at least one of neodymium-based magnets or samarium-cobalt magnets.

[0018] According to another aspect of this disclosure, the at least one low coercivity magnet comprises a ferrite-based magnet.

[0019] According to another aspect of this disclosure, the highly coercive magnet is segmented.

[0020] According to another aspect of this disclosure, the low coercivity magnet and the high coercivity magnet are curved and have radial magnetization.

[0021] According to another aspect of this disclosure, at least one of the highly coercive magnets is substantially parallel to the radius of the magnetic pole.

[0022] According to another aspect of this disclosure, the inner layer of the low coercivity magnet has a V-shaped structure.

[0023] According to several aspects of this disclosure, a method for manufacturing a permanent magnet rotor assembly is provided. The method includes laminating sheets of multiple core materials to form an annular stack of rotor laminations. These sheets have inner axial surfaces that collectively define a set of first openings through the sheets of core material and a set of second openings through the core material. The method further includes positioning a first arrangement of permanent magnets into a corresponding first opening in the set of first openings, and positioning a second arrangement of permanent magnets into a corresponding second opening in the set of second openings. The first arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets. The second arrangement of permanent magnets is also arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets.

[0024] According to another aspect of this disclosure, the method further includes positioning a third arrangement of permanent magnets within a corresponding third opening of a set of third openings. The third arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets.

[0025] The above features and advantages, as well as other features and advantages, of the currently disclosed systems and methods are readily apparent from the detailed description, including the claims and examples given in conjunction with the accompanying drawings. Attached Figure Description

[0026] This disclosure will be more fully understood through this detailed description and accompanying drawings, wherein:

[0027] Figure 1 This is a perspective view showing an example of a vehicle with an electric motor according to the present disclosure, the electric motor having a rotor and a stator.

[0028] Figure 2 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein the rotor has an eight-pole configuration and the magnetic pole portion comprises two layers.

[0029] Figure 3 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein the magnetic pole portion comprises three layers.

[0030] Figure 4 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein at least one of the neodymium-based magnets is substantially parallel to the radius of the magnetic pole portion.

[0031] Figure 5 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein at least two of the ferrite permanent magnets are V-shaped.

[0032] Figure 6 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, which includes ribs and a central column for high-speed operation.

[0033] Figure 7 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in an electric motor, where the ferrite permanent magnet has a curved structure.

[0034] Figure 8 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein the rotor comprises eight magnetic pole portions and each magnetic pole portion has two layers of permanent magnets.

[0035] Figure 9 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein the rotor has a six-pole configuration and the magnetic pole portion comprises two layers.

[0036] Figure 10 It is shown that, according to this disclosure Figure 1 The diagram shows a plan view of the magnetic pole portion of the rotor in the electric motor, wherein the rotor comprises six magnetic pole portions and each magnetic pole portion has two layers of permanent magnets.

[0037] Figure 11 This illustrates the method for manufacturing such as according to the present disclosure. Figure 1 The flowchart shows a method for assembling a permanent magnet rotor. Detailed Implementation

[0038] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or its uses. Furthermore, it is not intended to be bound by any express or implied theory set forth in the foregoing background, summary of the invention, or the following detailed description. It should be understood that similar or corresponding parts and features are always indicated by corresponding reference numerals in the various figures.

[0039] Several examples of this disclosure illustrated in the accompanying drawings will now be referred to in detail. Wherever possible, the same or similar reference numerals are used in the drawings and description to refer to the same or similar parts or steps. The drawings are simplified and not drawn to scale. The following description is exemplary in nature only and is not intended to limit the disclosure, its application, or its uses.

[0040] This document discloses a permanent magnet rotor assembly for an electric motor, an electric vehicle, and a method thereof. The permanent magnet rotor assembly includes an arrangement of combined permanent magnets, comprising high-coercivity magnets and low-coercivity magnets. Using the magnet combination described herein reduces dependence on rare-earth materials, while using similar permanent magnet blocks facilitates the fabrication and assembly of the permanent magnet rotor assembly. The permanent magnet rotor assembly described herein uses one building block for each permanent magnet type, reducing the total number of permanent magnet sizes to two for two magnet arrangements. For three magnet arrangements, the magnets can have three or four sizes. Furthermore, in terms of torque generation, the permanent magnet rotor assembly described herein is characterized by a mechanism that simultaneously contributes to maximizing the torque of the high-coercivity component.

[0041] Figure 1 A motor vehicle 10 with an electric drive system is schematically shown, which includes an electric motor 12 in the form of an electric motor / generator unit and wheels 14 driven by the electric motor 12. The electric motor 12 includes a stator 16 and a permanent magnet rotor assembly 18 reinforced and assembled according to this disclosure. The described permanent magnet rotor assembly 18 can benefit several types of wheeled and / or tracked land vehicles, propeller-driven ships and aircraft, mobile work platforms, etc. Non-vehicle systems can also benefit from this disclosure, including, for example, electrified powertrain architectures, power units, mobile platforms, robots, lifting or conveying equipment, etc. Figure 1 The motor vehicle 10 shown illustrates only one possible beneficial application.

[0042] The term "vehicle" as used herein is not limited to automobiles. While this paper primarily describes the technology in conjunction with electric vehicles and hybrid electric vehicles, the technology is not limited to electric vehicles and hybrid electric vehicles. These concepts can be used in a wide range of applications, such as in conjunction with components used in motorcycles, mopeds, locomotives, aircraft, ships and other vehicles, as well as in other applications using batteries, such as portable power stations (such as those used to power remote work sites), emergency backup power, and permanent power stations associated with buildings and equipment, all of which can be powered by, for example, solar or wind power systems, the mains power grid and fuel-based generators (such as gasoline, propane, kerosene or diesel generators) and Stirling engines.

[0043] Figure 1The illustrated electric motor 12 includes a stator 16 and a permanent magnet rotor assembly 18. As understood in the art, the stator 16 may include slots wound or filled with conductive stator windings (not shown) such that, when energized, the interaction between the stator 16 and the permanent magnet rotor assembly 18 causes the permanent magnet rotor assembly 18 to rotate. The permanent magnet rotor assembly 18 is coupled via an output member (not shown) to one or more wheels 14 disposed on a drive shaft (not shown).

[0044] Figure 1 The electric motor 12 is schematically shown, with the stator 16 arranged coaxially relative to the permanent magnet rotor assembly 18 in a typical radial flux configuration. This disclosure can also be extended to axial flux configurations. In some examples, the electric motor 12 can be configured as a multiphase / AC traction or propulsion motor.

[0045] Now refer to Figure 2 It provides Figure 1 A schematic plan view of a representative magnetic pole portion 20 of the rotor assembly 18 shown, wherein the magnetic pole portion 20 includes an annular stack of rotor lamination layers (or "rotor laminations") 22, one of which originates from... Figure 2 The rotor lamination 22, constructed from a core material such as, but not limited to, silicon steel (FeSi) and / or cobalt steel (FeCo), has inner axial surfaces 24, 26 that collectively define a first plurality of openings 28 through the core material of the rotor lamination 22 and a second plurality of openings 30 through the core material of the rotor lamination 22.

[0046] A plurality of permanent magnets 32 are disposed within a plurality of openings 28 in the core material passing through the rotor laminations 22. Each of the plurality of permanent magnets 32 is disposed within a corresponding opening in one of the plurality of openings 28 in the core material passing through the rotor laminations 22. The plurality of permanent magnets 32 include highly coercive magnets, such as, but not limited to, rare-earth magnets (e.g., neodymium-based (Nd) magnets and / or samarium (Sm) magnets). In a specific example, the plurality of permanent magnets 32 include neodymium iron boron (NdFeB) magnets containing dysprosium (Dy), which have high magnetic strength. Adding dysprosium to NdFeB magnets enhances high-temperature performance by increasing coercivity or resistance to demagnetization. In another example, the highly coercive magnets may have a square or rectangular structure and in some cases may be segmented, but not segmented in the axial direction as in conventional topologies. Multiple magnet segments may be combined to form a block.

[0047] A second plurality of permanent magnets 34 are disposed within a second plurality of openings 30 in the core material passing through the rotor laminations 22, wherein each corresponding permanent magnet of the second plurality of permanent magnets 34 is disposed within a corresponding opening in one of the second plurality of openings 30 in the core material passing through the rotor laminations 22. The second plurality of permanent magnets 34 include low coercivity magnets, such as, but not limited to, magnets containing less than about 10% by weight of rare earth elements and / or less than about 1% by weight of heavy rare earth elements (e.g., FeN, ferrite, Alinco, and / or ceramic magnets). Ferrite magnets, also known as ceramic magnets, are permanent magnets formed from composite materials of iron oxide (Fe2O3) and other metallic elements (e.g., barium or strontium). Compared to other types of magnets, ferrite magnets are inexpensive, corrosion-resistant, and have high resistance to demagnetization. Although the second plurality of permanent magnets 34 includes magnets containing less than about 10% by weight of rare earth elements and / or less than about 1% by weight of heavy rare earth elements, it should be understood that some of the magnets in the second plurality of permanent magnets 34 may contain more than about 10% by weight of rare earth elements and / or more than 1% by weight of heavy rare earth elements. The term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±1%.

[0048] In some cases, the first plurality of permanent magnets 32 and / or the second plurality of permanent magnets 34 may have parallel magnetization. For example, each of these permanent magnets has magnetic dipoles aligned in a configuration parallel to an external magnetic field, such as... Figure 2 As indicated by arrow 36. Because these magnets are permanent magnets, the magnetic dipoles remain aligned even after the external magnetic field is removed. Figure 2 A flux guiding mechanism is shown that allows for the use of equivalent neodymium blocks, in addition to enabling higher electromagnetic frequencies (EMF) and torque.

[0049] Furthermore, each of the permanent magnets 32 and 34 can be a separate segment or a single magnet with an integral structure, and these magnets can be combined to form block 38. For example, as Figure 2 As shown, the first permanent magnet 32A, the second permanent magnet 32B, and the third permanent magnet 32C are combined to form block 38. Although Figure 2 The block 38 shown is formed from the permanent magnets of the first plurality of permanent magnets 32; however, it should be understood that the second plurality of permanent magnets 34 may also be combined to form the block. Each permanent magnet 32A, 32B, 32C of the block 38 can be bonded together using an adhesive (such as an epoxy or phenolic resin adhesive). For example, the epoxy or phenolic resin adhesive may include polyurethane, benzoxazine, bismaleimide, methacrylate, etc. It should be understood that the adhesive may include other suitable adhesives.

[0050] also, Figure 2 The first plurality of permanent magnets 32 and the second plurality of permanent magnets 34 shown herein both have rectangular structures; however, it should be understood that each or any of the permanent magnets 32, 34 may have other structures as shown below.

[0051] Figure 2 It shows Figure 1 The rotor assembly 18 shown has a double-layer pole portion 20. In this example, the first layer 40 includes portions of a first plurality of permanent magnets 32 (shown as segmented blocks) arranged near the outer radial edge 42 of the pole portion 20, and portions of a second plurality of permanent magnets 34 (shown as having one ferrite magnet). The second layer 44 includes another portion of the first plurality of permanent magnets 32 (shown as segmented blocks) arranged closer to the inner radial edge 46 of the pole portion 20 than the first layer 40, and another portion of the second plurality of permanent magnets 34 (shown as having two ferrite blocks). The use of a combination of the first plurality of permanent magnets 32 and the second plurality of permanent magnets 34 facilitates efficient manufacturing while enabling a reduction in the number of the first plurality of permanent magnets 32 (e.g., Nd-based magnets) while maintaining the same or similar torque generation. Furthermore, this double-layer pole portion 20 facilitates a reduction in the axially inward Nd-based magnets and a reduction in eddy current losses.

[0052] Figure 3 It shows Figure 1 The rotor assembly shown has a three-layer pole section 20, comprising a first layer 40, a second layer 44, and a third layer 48. The first layer 40 has a first portion of a plurality of first permanent magnets 32 and a first portion of a plurality of second permanent magnets 34 (shown as a ferrite magnet) arranged near the outer radial edge 42 of the pole section 20. The second layer 44 includes a second portion of the plurality of first permanent magnets 32 and a second portion of the plurality of second permanent magnets 34 (shown as having three ferrite magnets) arranged near the inner radial edge 46 of the pole section 20. The third layer 48 includes a third portion of the plurality of first permanent magnets 32 and a third portion of the plurality of second permanent magnets 34 (shown as having two ferrite magnets) disposed between the first layer 40 and the second layer 44. Furthermore, the third layer 48 is disposed in a third plurality of openings 50 through the core material of the rotor laminations 22. The three-layer pole section 20 facilitates ease of manufacture and reduces the number of Nd-based magnets required to produce the same or similar torque.

[0053] Figure 4A double-layered magnetic pole portion 20 is shown, with a first layer 40 and a second layer 44 substantially parallel to each other. In this example, the first layer 40 includes portions of a first plurality of permanent magnets 32 arranged near the outer radial edge 42 of the magnetic pole portion 20 and portions of a second plurality of permanent magnets 34 (shown as having one ferrite magnet). The second layer 44 includes another portion of the first plurality of permanent magnets 32 and another portion of the second plurality of permanent magnets 34 (shown as having two ferrite blocks) arranged closer to the inner radial edge 46 of the magnetic pole portion 20 than the first layer 40. In the second layer 44, this portion of the first plurality of permanent magnets 32 extends substantially parallel to the radius r of the magnetic pole portion 20. The term "substantially" is understood by those skilled in the art. Alternatively, the term "substantially" can be defined as being aligned to within 10° of the radius r. This configuration with a flux guiding mechanism facilitates torque maximization and efficient utilization of the neodymium-based magnets in the first plurality of neodymium-based magnets.

[0054] Figure 5 A bilayer pole section 20 comprising a V-shaped ferrite magnet structure is shown. In this example, the first layer 40 includes portions of a first plurality of permanent magnets 32 and a second plurality of permanent magnets 34 (shown as having one ferrite magnet) arranged near the outer radial edge 42 of the pole section 20. The second layer 44 includes another portion of the first plurality of permanent magnets 32 and another portion of the second plurality of permanent magnets 34 (shown as having two ferrite blocks, wherein the two ferrite magnets are arranged relative to each other in a “V” shape at an angle α) closer to the inner radial edge 46 of the pole section 20 than the first layer 40. In the second layer 44, the two ferrite blocks can be at a variety of angles determined to maximize torque while minimizing demagnetization resistance.

[0055] Figure 6 A double-layered magnetic pole portion 20, including a configuration for ribs used in high-speed operation, is shown. In this example, the first layer 40 includes portions of a first plurality of permanent magnets 32 and a second plurality of permanent magnets 34 (shown as having one ferrite magnet) arranged near the outer radial edge 42 of the magnetic pole portion 20. The second layer 44 includes another portion of the first plurality of permanent magnets 32 and another portion of the second plurality of permanent magnets 34 (shown as having two ferrite blocks) arranged near the inner radial edge 46 of the magnetic pole portion 20. Within the second layer 44, these two ferrite blocks are separated by a central post 52. In this case, the central post 52 is the portion of the rotor lamination 22 extending between each of the second plurality of permanent magnets 34 (e.g., the two ferrite magnets). Including the central post 52 enables higher-speed operation by means of side ribs without restricting the radially inward extension of the Nd-based magnets.

[0056] Figure 7A double-layer magnetic pole portion 20 is shown, comprising a second plurality of permanent magnets 34 with curved structures. In this example, the first layer 40 includes portions of the first plurality of permanent magnets 32 and the second plurality of permanent magnets 34 (shown as having one ferrite magnet) arranged near the outer radial edge 42 of the magnetic pole portion 20. The second layer 44 includes another portion of the first plurality of permanent magnets 32 and the second plurality of permanent magnets 34 (shown as having two ferrite blocks) arranged near the inner radial edge 46 of the magnetic pole portion 20. Figure 7 As shown, each of the second plurality of permanent magnets 34 includes a first curved surface 54 and a second curved surface 56. Furthermore, the inner axial surfaces 24, 26 of each of the second plurality of openings 30 have curved profiles corresponding to the first curved surface 54 and the second curved surface 56 of the second plurality of permanent magnets 34, respectively. Implementing curved magnets (the curved second plurality of permanent magnets 34 in this example) simplifies manufacturing because curved ferrite magnets are easier to manufacture.

[0057] Figure 8 It shows Figure 1 The rotor assembly 18 depicted includes a double-layered magnetic pole portion 20 having an eight-pole configuration, including non-limiting examples of specific optimal ranges, where these ranges are given in terms of angles or distances and normalized relative to the outer radius r of the rotor assembly 18. The magnetic pole portion 20 includes a first layer 40 and a second layer 44. For example, the half-pole span angle θ between the inner vertex 58 of one of the first plurality of permanent magnets 32 and the radius r extending through the middle of the magnetic pole portion 20 can be between 16.8° and 17.85°, or between 45% and 65% of the half-pole span. The height h of one of the second plurality of permanent magnets 34 (e.g., a ferrite magnet) f It can be between 7.5 mm and 9 mm, or between 10% and 14% of the outer radius r. The height h between the first layer 40 and the second layer 44. l (As shown, for example, between ferrite blocks) can be 0.85-3 mm or between 0.5% and 4.5% of the outer radius r. The depth d of the V-shape between the multiple permanent magnets in the second plurality of permanent magnets 34 can be 3 mm or between 3% and 4% of the outer radius r. The height h between the first layer 40 and the outer radial edge 42 ag It can be 5.4-7.5 mm or between 5% and 11% of the outer radius r. The height h of one of the first plurality of permanent magnets 32. N It can be between 3.7mm and 4mm, or between 4% and 7% of the outer radius r. The width w of the outer layer of one of the first plurality of permanent magnets 32. olIt can be between 0 mm and 0.35 mm, or between 0% and 5% of the outer radius r. The width w of the inner layer of one of the first plurality of permanent magnets 32. in It can be between 0 mm and 0.5 mm, or between 0% and 5% of the outer radius r. The width w between the side edge 60 of the magnetic pole portion and one of the permanent magnets 32 located in the second layer 44. fpm It can be between 7mm and 11.4mm, or between 8.5% and 15.6% of the outer radius r. The width w between the first layer 40 and the second layer 44. L It can be between 1.5mm and 3.4mm, or between 3% and 10% of the magnetic pole span. These values ​​are exemplary, and it should be understood that other values, angles, and / or dimensions can be used.

[0058] Figure 9 It shows Figure 1 The rotor assembly 18 shown has a double-layered magnetic pole portion 20. In this example, the rotor assembly 18 includes a six-pole portion configuration and is located near... Figure 1 The stator 16 is arranged as depicted in the figure. In this example, the first layer 40 includes portions of a first plurality of permanent magnets 32 (shown as segmented blocks) arranged near the outer radial edge 42 of the pole portion 20 and portions of a second plurality of permanent magnets 34 (shown as having one ferrite magnet). The second layer 44 includes another portion of the first plurality of permanent magnets 32 (shown as segmented blocks) arranged closer to the inner radial edge 46 of the pole portion 20 than the first layer 40, and another portion of the second plurality of permanent magnets 34 (shown as having two ferrite blocks). The use of a combination of the first plurality of permanent magnets 32 and the second plurality of permanent magnets 34 promotes efficient manufacturing while enabling a reduction in the number of the first plurality of permanent magnets 32 (e.g., Nd-based magnets) while maintaining the same or similar torque generation. Furthermore, this dual-layer pole portion 20 facilitates a reduction in the axially inward Nd-based magnets and a reduction in eddy current losses.

[0059] Figure 10 It shows Figure 1The rotor assembly 18 depicted includes a double-layer magnetic pole portion 20 having an eight-pole parameter configuration, which includes non-limiting examples of specific optimal ranges, wherein these ranges are given in terms of angles or distances and normalized relative to the outer radius r of the rotor assembly 18 and / or the double-layer magnetic pole portion 20. The double-layer magnetic pole portion 20 includes a first layer 40 and a second layer 44. For example, the half-pole span angle θ between the inner vertex 58 of one of the first plurality of permanent magnets 32 and the radius r extending through the middle of the magnetic pole portion 20 can be between 16.45° and 19.5°, or between 45% and 65% of the half-pole span. The height h of one of the second plurality of permanent magnets 34 (e.g., a ferrite magnet) f It can be between 6mm and 8mm, or between 10% and 14% of the outer radius r. The height h between the first layer 40 and the second layer 44. l (For example, shown between ferrite blocks) can be between 0 mm and 2.5 mm, or between 0.5% and 4.5% of the outer radius r. The depth d of the V-shape between the plurality of permanent magnets in the second plurality of permanent magnets 34 can be between 2 mm and 4 mm, or between 0% and 7% of the outer radius r. The height h between the first layer 40 and the outer radial edge 42 ag It can be 3-6 mm or between 5% and 11% of the outer radius r. The height h of one of the first plurality of permanent magnets 32. N It can be between 2.7mm and 3.4mm, or between 4% and 7% of the outer radius r. The width w of the outer layer of one of the first plurality of permanent magnets 32. ol It can be between 0 mm and 0.35 mm, or between 0% and 5% of the outer radius r. The width w of the inner layer of one of the first plurality of permanent magnets 32. il It can be between 0 mm and 0.3 mm, or between 0% and 5% of the outer radius r. The width w between the side edge 60 of the magnetic pole portion and one of the permanent magnets 32 located in the second layer 44. fpm It can be between 5mm and 9mm, or between 8.5% and 15.6% of the outer radius r. The width w between the first layer 40 and the second layer 44. L It can be between 1 mm and 3.4 mm, or between 3% and 10% of the magnetic pole span. These values ​​are exemplary, and it should be understood that other values, angles, and / or dimensions can be used.

[0060] Reference Figure 11 According to this disclosure, a method 100 for manufacturing a permanent magnet rotor assembly 18 is proposed. The method begins at block 102.

[0061] Box 102 describes laminating multiple sheets of magnetic core material to form an annular stack and rotor lamination 22. The sheets laminating multiple magnetic core materials (e.g., steel) may include materials of choice, such as silicon steel, due to its good magnetic properties and low core losses. For example, the silicon content of the silicon steel may vary and may include grades such as M19, M27, and / or M36. The individual steel sheets may be punched or stamped into specific shapes and sizes suitable for rotor use. Laminating multiple sheets of magnetic core material may also include applying an insulating material (such as varnish or paint) to these sheets using a sprayer or some other suitable device. Laminating these sheets can reduce eddy current losses by electrically isolating each lamination. These sheets (or “rotor lamination 22”) have inner axial surfaces 24, 26 that collectively define a first set of openings 28 through the magnetic core material and a second set of openings 30 through the magnetic core material.

[0062] Box 104 describes positioning a first arrangement of permanent magnets into a corresponding first opening within the set of first openings. Positioning the first arrangement of permanent magnets (or "first layer 40") may include using, for example, a robot to place the first arrangement of permanent magnets into the first opening 28. The first arrangement of permanent magnets is in a hybrid magnet configuration because the first arrangement includes at least one of a first plurality of permanent magnets 32 and at least one of a second plurality of permanent magnets 34. The hybrid magnet configuration may include at least one low-coercivity magnet surrounded by at least two high-coercivity magnets.

[0063] Box 106 describes positioning a second arrangement of permanent magnets into a corresponding second opening within the set of second openings. Positioning the second arrangement of permanent magnets (or "second layer 44") may include using, for example, a robot to place the second arrangement of permanent magnets (e.g., second layer 44) into the second opening 30. The second arrangement of permanent magnets is in a hybrid magnet configuration because the second arrangement includes at least one of a first plurality of permanent magnets 32 and at least one of a second plurality of permanent magnets 34. The hybrid magnet configuration may include at least one low coercivity magnet surrounded by at least two high coercivity magnets.

[0064] Option box 108 describes positioning a third arrangement of permanent magnets into a corresponding third opening in a set of third openings. In some cases, a third arrangement of permanent magnets (e.g., a third layer 48) may be implemented. Positioning the third arrangement of permanent magnets (or “third layer 48”) may include using, for example, a robot to place the third arrangement of permanent magnets (e.g., third layer 48) into a set of third openings. The third arrangement of permanent magnets is in a hybrid magnet configuration because the third arrangement includes at least one of a first plurality of permanent magnets 32 and at least one of a second plurality of permanent magnets 34. Similarly, the hybrid magnet configuration may include at least one low-coercivity magnet surrounded by at least two high-coercivity magnets.

[0065] The permanent magnet rotor assembly 18 for the electric motor 12 disclosed herein offers advantages and benefits over the prior art. The permanent magnet rotor assembly 18 facilitates efficient manufacturing and assembly because it comprises similar magnets. Furthermore, the permanent magnet rotor assembly 18 maximizes torque and efficient utilization of the Nd-based magnets through flux guidance and a V-shaped ferrite magnet configuration. The permanent magnet rotor assembly 18 contributes to a reduction in the cost of Nd-based magnets while achieving the same or similar torque generation as when using a dual-magnet layer, a reduction in eddy current losses in the Nd-based magnets, and a reduction in axial section. Moreover, when using side ribs and a center column 52, the permanent magnet rotor assembly 18 facilitates higher speed operation.

[0066] This description is illustrative in nature and is not intended to limit the scope of this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in a wide variety of forms. Therefore, although this disclosure includes specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, description, and appended claims.

Claims

1. A permanent magnet rotor assembly for an electric motor, comprising: An annular stack comprising a rotor lamination layer or rotor lamination constructed of a magnetic core material, the rotor lamination having an inner axial surface that collectively defines a first set of openings through the magnetic core material and a second set of openings through the magnetic core material, wherein the annular stack includes at least one magnetic pole, the magnetic pole comprising: A first arrangement of permanent magnets, wherein each corresponding permanent magnet of the first arrangement is disposed within a corresponding first opening in one of the set of first openings, and wherein the first arrangement of permanent magnets is arranged according to a hybrid magnet configuration having at least one low-coercivity magnet surrounded by at least two high-coercivity magnets; and A second arrangement of permanent magnets, wherein each corresponding permanent magnet of the second arrangement is disposed within a corresponding second opening in the set of second openings, wherein the second arrangement of permanent magnets is arranged in a hybrid magnet configuration having at least one low coercivity magnet surrounded by at least two high coercivity magnets.

2. The permanent magnet rotor assembly according to claim 1, wherein, The at least two highly coercive magnets include at least one of neodymium-based magnets or samarium-cobalt magnets.

3. The permanent magnet rotor assembly according to claim 1, wherein, The at least one low coercivity magnet includes a ferrite-based magnet.

4. The permanent magnet rotor assembly according to claim 1, wherein, The high coercivity magnet has parallel magnetization.

5. The permanent magnet rotor assembly according to claim 1, wherein, The high coercivity magnet is segmented.

6. The permanent magnet rotor assembly according to claim 1, wherein, The at least one low coercivity magnet is curved and has radial magnetization.

7. The permanent magnet rotor assembly according to claim 1, wherein, At least one of the highly coercive magnets is parallel to the radius of the magnetic pole.

8. The permanent magnet rotor assembly according to claim 1, wherein, The inner layer of the at least one low coercivity magnet has a V-shaped structure.

9. The permanent magnet rotor assembly according to claim 1, wherein, Two low-coercivity magnets are separated by a central column.

10. The permanent magnet rotor assembly according to claim 1, wherein, The high coercivity magnet has a different size than the low coercivity magnet, and each magnetic pole includes only two or three magnet sizes.

Images