Motor

Abstract

The electric machine includes a rotationally fixed stator defining an axis of rotation of the electric machine and having a plurality of stator poles arranged about the axis of rotation. The electric machine also has a rotor rotatably mounted coaxially with the axis of rotation and axially spaced from the stator, the rotor having a plurality of permanent magnets facing the stator poles. Each stator pole includes: a plurality of ferromagnetic laminations in a stack of laminations extending from a radially inward extent to a radially outward extent relative to an axis of rotation; and a ferromagnetic composite pole portion attached to a radially outward extent or a radially inward extent of the stack of laminations of the stator poles.

Description

Technical Field

[0001] introduction

[0002] The present disclosure belongs to the field of electric machines. Background Art

[0003] Electric machines, such as motors and generators, are used in many applications, including propulsion of motor vehicles. One inefficiency of electric machines and other devices that employ time-varying magnetic fields is the generation of eddy currents in the ferromagnetic components of the electric machine. Such eddy currents generate ohmic heating that reduces the efficiency of the electric machine.

[0004] Permanent magnet electric machines have the potential to provide high power density and high efficiency in products such as electric vehicles. Improvements in permanent magnet electric machines that reduce inefficiencies caused by eddy current generation may be advantageous. Summary of the invention

[0005] The motor includes a rotationally fixed stator, the stator defining the rotation axis of the motor and having a plurality of stator poles, the stator poles being arranged around the rotation axis. The motor also includes a rotor, the rotor being rotatably mounted coaxially with the rotation axis and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles. Each stator pole includes: a plurality of ferromagnetic laminations in a lamination stack, the lamination stack extending from a radially-inward extent to a radially outward extent relative to the rotation axis; and a ferromagnetic composite pole portion, the ferromagnetic composite pole portion being attached to the radially outward extent or the radially inward extent of the lamination stack of the stator pole.

[0006] In an improvement, each stator pole may comprise a plurality of ferromagnetic composite pole sections attached to both the radially outward extent and the radially inward extent of the lamination stack of the stator pole. Alternatively, the ferromagnetic composite pole sections may comprise a soft magnetic composite or polymer composite.

[0007] In addition, each stator pole may have an electrical winding therearound, the electrical winding defining a mechanical interface region between the electrical winding and the (one or more) ferromagnetic composite pole portions of the stator pole, wherein the (one or more) ferromagnetic composite pole portions are rounded in the mechanical interface region.

[0008] In an electrical machine, the ferromagnetic composite pole portion(s) may be located in the edge region(s) of the magnetic field generated by the permanent magnets of the rotor.

[0009] Furthermore, the electric machine may comprise a second rotor rotatably mounted coaxially with the axis of rotation and axially spaced apart from the stator, the second rotor comprising a second plurality of permanent magnets facing the stator poles.

[0010] The vehicle may include: an electric machine; a source of DC electrical energy; an inverter coupled to the source of DC electrical energy and to the electric machine; and an inverter controller coupled to the inverter to control the electric machine as a motor to provide propulsion for the vehicle.

[0011] The second electric machine includes a rotationally fixed stator, the stator defining an axis of rotation of the electric machine and having a plurality of stator poles, the stator poles being arranged around the axis of rotation. The electric machine additionally includes a rotor, the rotor being rotatably mounted coaxially with the axis of rotation and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles. Each stator pole has: a plurality of ferromagnetic laminations stacked in a first lamination stack, the first lamination stack extending from a radially inward extent to a radially outward extent relative to the axis of rotation; and a pole portion attached to the radially outward extent or the radially inward extent of the first lamination stack, the pole portion including a second plurality of ferromagnetic laminations, the second plurality of ferromagnetic laminations being stacked in a direction different from the first lamination stack of the stator pole.

[0012] As an alternative to the second electric machine, each stator pole may have a second pole portion attached to the radially outward extent or the radially inward extent of the first lamination stack, the second pole portion having a third plurality of ferromagnetic laminations, the third plurality of ferromagnetic laminations being stacked in a different direction than the first lamination stack of the stator pole. The pole portion and the second pole portion may be located in an edge region of the magnetic field generated by the permanent magnets of the rotor. The electric machine may further have a second rotor rotatably mounted coaxially with the axis of rotation and axially spaced from the stator, the second rotor comprising a second plurality of permanent magnets facing the stator poles.

[0013] The additional motor comprises: a rotationally fixed stator having stator poles, the stator poles comprising ferromagnetic laminations; a rotor rotatably arranged relative to the stator and separated from the stator by an air gap, the rotor having permanent magnetic rotor poles facing the stator poles and generating a magnetic field; and non-laminated ferromagnetic pole portions, the non-laminated ferromagnetic pole portions being attached to the stator poles in the edge region of the magnetic field generated by the permanent magnetic rotor poles. Alternatively, the non-laminated ferromagnetic pole portions comprise a composite ferromagnetic material or a soft magnetic composite material. The motor may include an electrical winding arranged around each stator pole. In addition, the motor may have a second rotor rotatably arranged relative to the stator and separated from the stator by a second air gap, the second rotor having a second permanent magnetic pole, the second permanent magnetic pole facing the stator pole and generating a magnetic field. The electric machine may be an electric motor, and the vehicle may include: the electric machine; a DC electrical energy source; an inverter coupled to the DC electrical energy source and to the electric machine; and an inverter controller coupled to the inverter to control the electric machine as an electric motor to provide propulsion for the vehicle.

[0014] The present disclosure also relates to the following technical solutions:

[0015] 1. A motor, comprising:

[0016] a rotationally fixed stator defining an axis of rotation of the electric machine and having a plurality of stator poles arranged about the axis of rotation; and

[0017] a rotor rotatably mounted coaxially with the rotation axis and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles;

[0018] Wherein, each stator pole includes: a plurality of ferromagnetic laminations in a lamination stack, wherein the lamination stack extends from a radially inward range to a radially outward range relative to the rotation axis; and a ferromagnetic composite pole portion, wherein the ferromagnetic composite pole portion is attached to the radially outward range or the radially inward range of the lamination stack of the stator pole.

[0019] 2. An electric motor according to Technical Solution 1, wherein each stator pole comprises a plurality of ferromagnetic composite pole portions, and the ferromagnetic composite pole portions are attached to both the radially outward extent and the radially inward extent of the lamination stack of the stator pole.

[0020] 3. The motor according to Technical Solution 2, wherein the ferromagnetic composite pole portion comprises a soft magnetic composite material.

[0021] 4. An electric motor according to Technical Solution 2, wherein the ferromagnetic composite pole portion comprises a polymer composite material.

[0022] 5. An electric motor according to Technical Solution 1, wherein each stator pole has an electrical winding arranged around it, and the electrical winding defines a mechanical interface region between the electrical winding and the ferromagnetic composite pole portion of the stator pole, wherein the ferromagnetic composite pole portion is circular in the mechanical interface region.

[0023] 6. An electric motor according to Technical Solution 2, wherein each stator pole has an electrical winding arranged around it, and the electrical winding defines a mechanical interface area between the electrical winding and the molded ferromagnetic pole part of the stator pole, wherein the molded ferromagnetic part is circular in the mechanical interface area.

[0024] 7. The electric machine according to technical solution 1, wherein the ferromagnetic composite pole portion is located in an edge region of a magnetic field generated by a permanent magnet of the rotor.

[0025] 8. The electric machine according to technical solution 2, wherein the ferromagnetic composite pole portion is located in an edge region of a magnetic field generated by a permanent magnet of the rotor.

[0026] 9. A vehicle comprising:

[0027] The motor according to technical solution 1;

[0028] DC power source;

[0029] an inverter coupled to the DC electrical energy source and to the electric machine; and

[0030] An inverter controller is coupled to the inverter to control the electric machine as a motor to provide propulsion for the vehicle.

[0031] 10. A motor, comprising:

[0032] a rotationally fixed stator defining an axis of rotation of the electric machine and having a plurality of stator poles arranged about the axis of rotation; and

[0033] a rotor rotatably mounted coaxially with the rotation axis and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles;

[0034] Wherein, each stator pole includes: a plurality of ferromagnetic laminations stacked in a first lamination stack, the first lamination stack extending from a radially inward range to a radially outward range relative to the rotation axis; and a pole portion, the pole portion attached to the radially outward range or the radially inward range of the first lamination stack, the pole portion including a second plurality of ferromagnetic laminations, the second plurality of ferromagnetic laminations being stacked in a direction different from the first lamination stack of the stator pole.

[0035] 11. An electric motor according to technical solution 10, wherein each stator pole includes a second pole portion, the second pole portion is attached to the radially outward range or the radially inward range of the first lamination stack, the second pole portion includes a third plurality of ferromagnetic laminations, and the third plurality of ferromagnetic laminations are stacked in a direction different from the first lamination stack of the stator pole.

[0036] 12. The electric motor according to technical solution 10, wherein the magnetic pole portion is located in an edge region of a magnetic field generated by a permanent magnet of the rotor.

[0037] 13. The motor according to technical solution 11, wherein the magnetic pole portion and the second magnetic pole portion are located in an edge area of ​​a magnetic field generated by a permanent magnet of the rotor.

[0038] 14. The motor according to Technical Solution 10 further includes a second rotor, which is rotatably mounted coaxially with the rotation axis and axially spaced apart from the stator, and the second rotor includes a second plurality of permanent magnets facing the stator poles.

[0039] 15. A motor, comprising:

[0040] a rotationally fixed stator having stator poles including ferromagnetic laminations;

[0041] a rotor rotatably arranged relative to the stator and separated from the stator by an air gap, the rotor including permanent magnet rotor poles facing the stator poles and generating a magnetic field; and

[0042] Non-laminated ferromagnetic pole sections are attached to the stator poles in edge regions of the magnetic field generated by the permanent magnet rotor poles.

[0043] 16. An electric motor according to Technical Solution 15, wherein the non-laminated ferromagnetic pole portion comprises a ferromagnetic composite material.

[0044] 17. An electric motor according to Technical Solution 15, wherein the non-laminated ferromagnetic pole portion comprises a soft magnetic composite material.

[0045] 18. The electric motor according to Technical Solution 15 further includes an electrical winding arranged around each stator pole.

[0046] 19. The motor according to Technical Solution 15 further includes a second rotor, which is rotatably arranged relative to the stator and separated from the stator by a second air gap, and the second rotor includes a second permanent magnet pole facing the stator pole and generating a magnetic field.

[0047] 20. A vehicle comprising:

[0048] The motor according to technical solution 15;

[0049] DC power source;

[0050] an inverter coupled to the DC electrical energy source and to the electric machine; and

[0051] An inverter controller is coupled to the inverter to control the electric machine as a motor to provide propulsion for the vehicle.

[0052] The above overview does not represent every embodiment or every aspect of the present disclosure. The above features and advantages of the present disclosure and other possible features and advantages will be apparent from the following detailed description of the embodiments and best modes for carrying out the present disclosure when combined with the accompanying drawings and the appended claims. In addition, the present disclosure expressly includes combinations and sub-combinations of the elements and features presented above and below. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a schematic diagram showing an electric machine and its associated electrical and electronic control components.

[0054] Figure 2 yes Figure 1 Exploded view of the motor parts.

[0055] Figure 3 Schematic showing the magnetic field lines emanating from the permanent magnets of an electric motor's rotor.

[0056] Figure 4 The magnetic field lines are shown entering the end of the motor stator laminations.

[0057] Figure 5 The magnetic field lines entering the face of the motor stator laminations are shown.

[0058] Figure 6 An alternative structure for the stator poles of an electric machine is shown.

[0059] Figure 7 A second alternative configuration for the stator poles of an electric machine is shown. DETAILED DESCRIPTION

[0060] The present disclosure may have embodiments in many different forms. Representative examples of the present disclosure are shown in the accompanying drawings and described in detail herein as non-limiting examples of the disclosed principles. For this reason, elements and limitations described in the abstract, introduction, summary, and detailed description but not explicitly set forth in the claims should not be incorporated into the claims individually or collectively by implication, inference, or otherwise.

[0061] For the purposes of the present description, unless otherwise stated, the use of the singular includes the plural and vice versa, the terms "and" and "or" shall be both conjunctions and disjunctive conjunctions, "any" and "all" shall mean "any and all", and the terms "include", "comprising", "including", "having", etc. shall mean "including but not limited to". In addition, approximate terms such as "approximately", "almost", "substantially", "roughly", "approximately" and the like may be used herein in the sense of "at, close to, or nearly at", or "within 0-5% thereof", or "within an acceptable manufacturing tolerance", or a logical combination thereof.

[0062] First reference Figure 1 , illustrated is an electric machine 10, such as an electric motor, a generator, or an electric generator. The electric machine 10 may be an axial flux permanent magnet electric machine. The electric machine 10 may have a non-rotating stator 12 attached to a housing (not shown). The stator 12 defines at its center an axis of rotation 14 for a permanent magnet rotor 16 and a permanent magnet rotor 18. The rotor 16 and the rotor 18 may be fixed to a common shaft 20 for rotation therewith, wherein the shaft 20 is supported by bearings in the housing of the electric machine 10 and is appropriately journaled for rotation within the stator 12. The rotor 16 is separated from the stator 12 by an air gap 17, and the rotor 18 is separated from the stator 12 by an air gap 19. Alternatively, the electric machine 10 may have only one rotor, or the electric machine 10 may have more than two rotors. The electric machine 10 may be an electric motor that can be used to provide propulsion to a vehicle 13, such as an electric vehicle or a hybrid electric vehicle, by being coupled to a drive axle or drive wheels of the vehicle 13.

[0063] The stator 12 is wound with electrical windings 21 that provide magnetic flux that interacts with the rotors 16 and 18 to generate mechanical rotational force from the motor 10 when the motor 10 is controlled to act as a motor. The electrical windings 21 can be appropriately interconnected, such as in a three-phase Y (or "star") configuration or a three-phase DELTA (or "delta") connection. The electrical windings 21 can be excited by a power inverter module (PIM) 31 that converts electrical energy from a direct current (DC) electrical energy source (such as energy stored in one or more traction batteries (B+) 22) into alternating current (AC) electrical energy to power the motor 10. An electronic control unit (ECU) 24 - which can be combined with the power inverter module 31 or can be a separate controller - can act as an inverter controller to control the operation of the power inverter module 31. The ECU 24 is an electronic controller that has sufficient electronic resources (microcontroller, memory, software, input, output, etc.) to control the motor 10. The ECU 24 may control the electric machine 10 as a motor through the power inverter module 31 to provide propulsion for the vehicle 13 .

[0064] The electric machine 10 may be characterized as an "axial flux" machine because the magnetic flux generated by the electrical windings 21 of the stator 12 travels generally axially, i.e., parallel to the axis of rotation 14 of the electric machine 10. This may be contrasted with a so-called "radial flux" machine in which the stator may be arranged around the rotor and the magnetic flux travels radially relative to the central axis of the machine.

[0065] Additional references Figure 2 , Figure 2 , portions of the stator 12, rotor 16, and rotor 18 are illustrated. The rotor 16 has a plurality of permanent magnets 30 arranged on the face of the rotor 16 and facing the stator 12, forming permanent magnetic poles facing the stator 12. Similarly, the rotor 18 has a plurality of permanent magnets 32 arranged on the face of the rotor 18 and facing the stator 12, forming permanent magnetic poles facing the stator 12. The winding 21 is arranged around the stator poles 23 of the stator 12 to generate a substantially axially extending magnetic flux from the stator poles 23 when the winding 21 is excited by the power inverter module 31. The stator poles 23 may be composed of ferromagnetic laminations attached together in a stack extending radially relative to the axis of rotation 14. The stator poles 23 may be a “segmented” stator 12 and may be held together by compression bands that compress the stator poles 23 to the hub of the stator 12 or by bonding to a housing (not shown) of the electric machine 10 .

[0066] The stator poles 23 may be comprised of ferromagnetic laminations 40, which may be electrically insulated from one another. The laminations comprising the stator poles 23 may include laminations 34 near the center of the stator poles 23 (the "center" of the stator poles 23 being referenced radially relative to the axis of rotation 14) and laminations 36 closer to the radially-inward or radially-outward extent of the stator poles 23 ("radially outward" and "radially inward" being referenced relative to the axis of rotation 14).

[0067] Additional references Figure 3 , schematically illustrates the magnetic field lines of a permanent magnet (such as permanent magnet 30) attached to rotor 16 or rotor 18. Near the center of permanent magnet 30 ("center" is referred to in the radial direction relative to central rotation axis 14), magnetic flux lines B1 tend to extend at right angles to the face of permanent magnet 30. However, closer to the top and bottom of permanent magnet 30 (such as Figure 3 There, the magnetic field lines B2 tend to deviate from the plane perpendicular to the permanent magnet 30. (Note that Figure 3 The transition between the magnetic field lines B1 extending approximately perpendicular to the face of the permanent magnet 30 and the magnetic field lines B2 deviating from approximately at right angles to the face of the permanent magnet 30 will be more Figure 3 As further referenced Figure 4 and Figure 5 As shown, edge phenomena can be a problem.

[0068] like Figure 4 As shown in FIG. 1 , in the region of the permanent magnet 30, the magnetic flux B1 of the permanent magnet 30 extends approximately at right angles to the face of the permanent magnet 30, and the magnetic flux B1 tends to enter the edge 35 of the laminations 34 of the stator 12. This generates eddy currents i1 that circulate around the flux lines B1. The eddy currents i1 generate wasteful ohmic heating, which reduces the efficiency of the motor 10. However, in Figure 4 In the case shown in , this eddy current i1 may be relatively small.

[0069] However, if Figure 5 As shown in FIG. 1 , in the case of edge phenomena near the edge of the permanent magnet 30, the magnetic flux B2 associated with the permanent magnet 30 may enter the face 38 of the lamination 36 rather than the end. Therefore, the surface area of ​​the lamination 36 exposed to the magnetic flux B2 is greater than that in FIG. Figure 4 Due to this larger surface area, and since eddy currents are proportional to the surface area, the eddy currents i2 generated and circulating around the magnetic flux line B2 are correspondingly larger. This results in a larger surface area than Figure 4 In the case of greater eddy current losses, Figure 4In this case, the magnetic flux lines are substantially perpendicular to the faces of the permanent magnets 30 and the rotor 16 .

[0070] refer to Figure 6 The improvement in reducing high eddy current losses is shown in the figure. Figure 6 , an improved stator pole 23' is illustrated. The stator pole 23' may also be composed of laminations 40. The pole portion 42 and the pole portion 44 may be attached to the radially inward range 43 and the radially outward range 45 ("radially inward" and "radially outward" are relative to the rotation axis 14) of the stack of laminations 40 of the stator pole 23', respectively. The pole portion 42 and / or the pole portion 44 may be composed of a composite material including a ferromagnetic material. One such ferromagnetic composite material is a soft magnetic composite material ("SMC"). SMC includes magnetic particles molded together but electrically insulated from each other. Other ferromagnetic composite materials including ferromagnetic particles in a polymer or other electrically insulating substrate may also be used. Therefore, the pole portion 42 and the pole portion 44 may not be stacked. The pole portion 42 and the pole portion 44 may be attached to the balance of the stator pole 23' by an adhesive or another suitable connection method. Since the ferromagnetic particles in the SMC, which may include pole portion 42 and pole portion 44, are electrically insulated from each other, the edge effects of permanent magnets 30 of rotor 16 will not cause Figure 5 The same high level of eddy currents as shown in FIG.

[0071] like Figure 6 As shown in FIG, pole segment 42 may have rounded corners 46 and pole segment 44 may have rounded corners 48. These rounded corners will increase the radius of winding 21 and thus reduce the stress on winding 21 in the mechanical interface area between winding 21 and pole segments 42 and 44.

[0072] refer to Figure 7 An alternative design for a stator pole 23 is shown. Here too, a stator pole 23 ″ is composed of a lamination stack 40 , on which a winding 21 is wound. The stacked magnetic pole portions 50 and the stacked magnetic pole portions 52 may be located at radially inward and radially outward ranges of the stator pole 23″, respectively (“radially inward” and “radially outward” are relative to the rotation axis 14). The stacked magnetic pole portions 50 and the stacked magnetic pole portions 52 may be composed of laminations of a conductive material (such as steel), which may be electrically insulated from each other. However, the stacked magnetic pole portions 50 and the stacked magnetic pole portions 52 may be at right angles to the stacking of the laminations 40. That is, although the laminations 40 may be stacked approximately in a radial direction relative to the rotation axis 14, the laminations of the stacked magnetic pole portions 50 and the stacked magnetic pole portions 52 may be stacked approximately tangentially relative to the rotation axis 14. The stacked magnetic pole portions 50 and the stacked magnetic pole portions 52 may be attached to the balancing piece of the stator pole 23″ by an adhesive or another suitable method. Therefore, a magnetic field such as B2 ( Figure 3 ) will not act like the magnetic field B2 does to the lamination 36 (e.g. Figure 5 ) into the large faces of the laminations of the laminated pole segments 50 and the laminated pole segments 52. Eddy currents and wasted ohmic heating will be reduced.

[0073] The detailed description and the accompanying drawings or drawings are support and description of the present teachings, but the scope of the present teachings is limited only by the claims. Although some best modes and other embodiments for carrying out the present teachings have been described in detail, there are various alternative designs and embodiments for practicing the present teachings defined in the appended claims. In addition, the present disclosure explicitly includes combinations and sub-combinations of the elements and features presented above and below.

Claims

1. A motor, comprising: a rotationally fixed stator defining an axis of rotation of the electric machine and having a plurality of stator poles arranged about the axis of rotation; and a rotor rotatably mounted coaxially with the rotation axis and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles; Wherein, each stator pole includes: a plurality of ferromagnetic laminations in a lamination stack, wherein the lamination stack extends from a radially inward range to a radially outward range relative to the rotation axis; and a ferromagnetic composite pole portion, wherein the ferromagnetic composite pole portion is attached to the radially outward range or the radially inward range of the lamination stack of the stator pole.

2. The motor according to claim 1, wherein: Each stator pole includes a plurality of composite ferromagnetic pole sections attached to both the radially outward extent and the radially inward extent of the lamination stack of the stator pole.

3. The motor according to claim 2, wherein: The ferromagnetic composite pole portion includes a soft magnetic composite material.

4. The motor according to claim 2, wherein: The ferromagnetic composite pole portion includes a polymer composite.

5. The motor according to claim 1, wherein: Each stator pole has an electrical winding disposed thereabout, the electrical winding defining a mechanical interface region between the electrical winding and the ferromagnetic composite pole portion of the stator pole, wherein the ferromagnetic composite pole portion is circular in the mechanical interface region.

6. The motor according to claim 2, wherein: Each stator pole has an electrical winding disposed thereabout, the electrical winding defining a mechanical interface region between the electrical winding and a molded ferromagnetic pole portion of the stator pole, wherein the molded ferromagnetic portion is circular in the mechanical interface region.

7. The motor according to claim 1, wherein: The ferromagnetic composite pole portions are located in edge regions of a magnetic field generated by permanent magnets of the rotor.

8. The motor according to claim 2, wherein: The ferromagnetic composite pole portions are located in edge regions of a magnetic field generated by permanent magnets of the rotor.

9. A vehicle comprising: The motor according to claim 1; DC power source; an inverter coupled to the DC electrical energy source and to the electric machine; and An inverter controller is coupled to the inverter to control the electric machine as a motor to provide propulsion for the vehicle.

10. A motor, comprising: a rotationally fixed stator defining an axis of rotation of the electric machine and having a plurality of stator poles arranged about the axis of rotation; and a rotor rotatably mounted coaxially with the rotation axis and axially spaced from the stator, the rotor including a plurality of permanent magnets facing the stator poles; Wherein, each stator pole includes: a plurality of ferromagnetic laminations stacked in a first lamination stack, the first lamination stack extending from a radially inward range to a radially outward range relative to the rotation axis; and a pole portion, the pole portion attached to the radially outward range or the radially inward range of the first lamination stack, the pole portion including a second plurality of ferromagnetic laminations, the second plurality of ferromagnetic laminations being stacked in a direction different from the first lamination stack of the stator pole.

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