ELECTRIC WORK MACHINE WITH SUBDITED INNER PERMANENT MAGNET

Abstract

An electric machine with an internal permanent magnet comprises a stator and a rotor. The rotor has a core with slots extending between its opposite ends. These slots contain a segmented magnet assembly comprising magnetic sections made of different magnetic materials. The segmented magnet assembly can be radially, axially, circumferentially, or in combinations thereof, and can include outer magnetic sections made of one magnetic material and inner magnetic sections made of a second magnetic material. Additionally, the segmented magnet assembly includes magnetic poles oriented radially, axially, or circumferentially.

Description

INTRODUCTION

[0001] The disclosure relates to internal permanent magnet (IPM) electric working machines. In particular, the disclosure relates to magnetic pole arrangements in IPM electric working machines.

[0002] High-performance electric working machines, such as IPM AC working machines used in electrified vehicle powertrains, can utilize rare-earth magnets, such as neodymium and samarium-cobalt magnets. Improved neodymium magnet properties, such as higher resistance to demagnetization (coercivity), improved temperature stability, or better performance under extreme conditions, can be achieved by adding heavy rare-earth elements (HREs), including dysprosium (Dy), terbium (Tb), and gadolinium (Gd). HRE magnets can be sensitive to the supply instability of the HRE elements. Some relief from HRE supply instability factors can be achieved through improvements in materials, such as interfacial diffusion processes that minimize material requirements.Due to HRE supply instability factors and other factors, it is generally desirable to reduce the HRE content of such magnets. SUMMARY

[0003] According to an exemplary embodiment, an electric working machine with an internal permanent magnet can include a rotor core having axially opposite ends and several slots, each slot extending through the rotor core between the axially opposite ends and comprising a subdivided magnet arrangement comprising at least one magnetic section of a first magnetic material and at least one magnetic section of a second magnetic material.

[0004] In addition to one or more of the features described here, the subdivided magnet arrangement is subdivided in a radial direction relative to a rotational axis of the rotor core.

[0005] In addition to one or more of the features described herein, the subdivided magnet arrangement comprises radially outer magnetic sections of the first magnetic material at radial ends of the subdivided magnet arrangement and at least one inner magnetic section of the second magnetic material arranged radially between the radially outer magnetic sections of the first magnetic material.

[0006] In addition to one or more of the features described here, the first magnetic material comprises a heavy rare-earth magnetic material and the second magnetic material comprises a non-heavy rare-earth magnetic material.

[0007] In addition to one or more of the features described here, the subdivided magnet arrangement is subdivided in an axial direction relative to a rotational axis of the rotor core.

[0008] In addition to one or more of the features described herein, the subdivided magnet arrangement may contain axially outer magnetic sections of the first magnetic material at axial ends of the subdivided magnet arrangement and may include at least one inner magnetic section of the second magnetic material arranged axially between the axially outer magnetic sections of the first magnetic material.

[0009] In addition to one or more of the features described here, the first magnetic material may include a heavy rare-earth magnetic material and the second magnetic material may include a non-heavy rare-earth magnetic material.

[0010] In addition to one or more of the features described here, the subdivided magnet arrangement is subdivided in a circumferential direction relative to a rotational axis of the rotor core.

[0011] In addition to one or more of the features described here, the subdivided magnet arrangement may contain magnetic poles oriented in an axial direction relative to a rotational axis of the rotor core.

[0012] In addition to one or more of the features described here, the subdivided magnet arrangement may contain magnetic poles oriented in a radial direction relative to a rotational axis of the rotor core.

[0013] In addition to one or more of the features described here, the subdivided magnet arrangement may contain magnetic poles oriented in a circumferential direction relative to a rotational axis of the rotor core.

[0014] In addition to one or more of the features described here, the first magnetic material may include a heavy rare-earth magnetic material and the second magnetic material may include a non-heavy rare-earth magnetic material.

[0015] In addition to one or more of the features described herein, the subdivided magnet arrangement may further comprise axially outer magnetic sections of the first magnetic material at the axial ends of the subdivided magnet arrangement, and the at least one inner magnetic section of the second magnetic material may be located axially between the axially outer magnetic sections of the first magnetic material.

[0016] In addition to one or more of the features described here, the first magnetic material may include a heavy rare-earth magnetic material and the second magnetic material may include a non-heavy rare-earth magnetic material.

[0017] In addition to one or more of the features described here, at least one of the radially outer magnetic sections of the first magnetic material at the radial ends of the subdivided magnetic arrangement and at least one of the inner magnetic sections of the second magnetic material are trapezoidal in shape.

[0018] In addition to one or more of the features described here, at least one of the radially outer magnetic sections of the first magnetic material is triangular in shape at the radial ends of the subdivided magnetic arrangement.

[0019] According to a further exemplary embodiment, an electric working machine with an internal permanent magnet can include a stator and a rotor comprising a rotor core having axially opposite ends and several slots, each slot extending through the rotor core between the axially opposite ends and comprising a partitioned magnet arrangement comprising at least one magnetic section of a first magnetic material and at least one magnetic section of a second magnetic material, wherein the partitioned magnet arrangement is partitioned in a radial direction relative to an axis of rotation of the rotor core and includes radially outer magnetic sections of the first magnetic material at radial ends of the partitioned magnet arrangement, and at least one inner magnetic section of the second magnetic material is located radially between the radially outer magnetic sections of the first magnetic material.wherein the subdivided magnet arrangement further comprises magnetic poles which are oriented in a circumferential direction relative to the axis of rotation of the rotor core.

[0020] In addition to one or more of the features described here, the first magnetic material may include a heavy rare-earth magnetic material and the second magnetic material may include a non-heavy rare-earth magnetic material.

[0021] In addition to one or more of the features described here, the first magnetic material may include a non-heavy rare-earth magnetic material and the second magnetic material may include a heavy rare-earth magnetic material.

[0022] According to a further exemplary embodiment, an electrified powertrain for a vehicle may include a battery pack, a traction inverter module (TPIM) connected to the battery pack and configured to convert a direct current (DC) voltage from the battery pack into an alternating current (AC) voltage, and a rotating electric working machine comprising a stator excited by the AC voltage of the TPIM and a rotor having a rotor core with axially opposite ends and multiple slots, each slot extending through the rotor core between the axially opposite ends, and a segmented magnet arrangement comprising at least one magnetic section of a first magnetic material and at least one magnetic section of a second magnetic material.wherein the subdivided magnet arrangement is subdivided in a radial direction relative to an axis of rotation of the rotor core and comprises radially outer magnetic sections of the first magnetic material at the radial ends of the subdivided magnet arrangement and at least one inner magnetic section of the second magnetic material is located radially between the outer magnetic sections of the first magnetic material, wherein the subdivided magnet arrangement further comprises magnetic poles oriented circumferentially relative to the axis of rotation of the rotor core, and comprises a rotor shaft connected to the rotor and configured to rotate about an axis of rotation cooperating with the rotor when the stator is excited, and comprises a gearbox coupled to the rotor shaft and driven by the electric working machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 an electrified powertrain according to one or more embodiments; Fig. 2 different features of an internal permanent magnet rotor according to one or more embodiments; Fig. 3A-E different embodiments of subdivided magnet arrangements according to one or more embodiments; Fig. 4A-C a side view of a rotor comprising a rotor core and subdivided internal permanent magnets according to one or more embodiments; and Fig. 5 different embodiments of subdivided magnet arrangements according to one or more embodiments. DETAILED DESCRIPTION

[0024] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. Throughout the drawings, corresponding reference numerals indicate similar or corresponding parts and features. A description of parts and features in one drawing shall be understood to apply to parts and features in other drawings that use the same reference numerals to the extent that such parts and features cannot otherwise be distinguished by examination of the drawing by a person skilled in the art or by an additional written description herein.

[0025] With reference to the drawings, in which similar reference numerals refer to the same or similar components in the multiple figures, an electrified powertrain 10 is shown in Fig. Figure 1 is shown schematically (e.g., for use on board an exemplary motor vehicle 11). The powertrain 10 comprises a rotating electric working machine 12, which has a rotor 12R and a stator 12S. The rotor 12R may contain internal permanent magnets. When the stator 12S is energized, the rotor 12R applies motor torque to a transmission 20 (e.g., an automatic step-through transmission). Although omitted for the sake of simplicity, the electrified powertrain 10 may also include an internal combustion engine configured to generate engine torque. If equipped with this, the generated engine torque can be supplied to the transmission 20 of the electric working machine 12 either alone or in conjunction with the engine torque.

[0026] If the vehicle is 11 of Fig. In embodiments of vehicle 11 as a hybrid electric vehicle, the electric work machine 12 and / or the power machine can drive the transmission 20. Alternatively, vehicle 11 can be a battery-powered electric vehicle, in which case the transmission 20 can be driven exclusively by the motor torque of the electric work machine 12. The disclosed improvements relate to the design of the electric work machine 12 and can be implemented without restriction in embodiments of the hybrid electric vehicle (HEV) and the electric vehicle (EV) of vehicle 11, as well as in non-vehicle applications such as power plants, lifting devices, mobile platforms, and robots.While the electric working machine 12 is described as a rotating electric working machine, certain applications, such as rail drive systems, may use a linear electric working machine in which the rotor, as is known among those skilled in the art, may be embodied in a linear equivalent to internal permanent magnets.

[0027] With continued reference to the exemplary vehicle 11 of Fig. 1. The electrified powertrain 10 can include an AC voltage bus 13. The AC voltage bus 13 can optionally be powered by a traction inverter module (TPIM) 28 coupled to a high-voltage battery pack (HV battery pack) 24, such as a lithium-ion, lithium-sulfur, nickel-metal hydride, or other high-voltage power supply. The AC voltage bus 13 provides an AC bus voltage (VAC) and carries AC current to or from the electric working machine 12. The motor torque of the excited electric working machine 12, when operated in a drive or motor mode, is transmitted to a rotor shaft 125 of the rotor 12R, the rotor shaft 125 being connected to the rotor 12R by means of journals, keys, or otherwise. The motor torque is then directed to a coupled load, such as the gearbox 20 and / or one or more road wheels 22.

[0028] The HV battery pack can be coupled to the TPIM 28 at a relatively high DC voltage (VDC) via a relatively high voltage DC bus (e.g., DC-Link) 15. The electrified powertrain 10 can also include a DC / DC converter 26 configured to decrease or increase a relatively high DC bus voltage (VDC) as needed. The DC / DC converter 26 is connected between the battery pack 24 and a relatively low voltage DC bus 16. In some configurations, an auxiliary battery pack 124 can be connected to the DC / DC converter 26 via the relatively low voltage DC bus 16. The auxiliary battery pack 124 can be implemented and configured as a lead-acid battery or a battery constructed from another application-appropriate chemical composition, e.g., B. to store an auxiliary voltage (VAUX) of 12-15 V or to supply it to one or more connected auxiliary devices (not shown).

[0029] The rotor 12R of the electric working machine 12 is arranged adjacent to the stator 12S and separated from it by an air gap. The stator 12S and the rotor 12R can be constructed from stacked thin sheets (e.g., of electrical steel or another ferrous material), each sheet typically being about 0.2 mm–0.5 mm thick, as average experts in the field will recognize. The sheets can be cut into their final shape by a punch and die, or they can be cut by a laser or by wire EDM.

[0030] The rotor 12R, which is schematically shown in Fig. Figure 1 shows an internal rotor groove characterized by cavities in the electrical steel sheets. Such rotor grooves can provide a flux barrier inside the rotor 12R and can include other rotor features, as further described herein. According to certain embodiments, the rotor grooves can be partially or completely filled with permanent magnets (PM).

[0031] Fig. Figure 2 shows an exemplary rotor core 201 of the rotor 12R from Fig. 1 according to a rotating internal permanent magnet (IPM) electric working machine. The rotor core 201 may be constructed from stacked thin sheets (e.g., electrical steel or another ferrous material), each sheet typically being about 0.2 mm–0.5 mm thick, as average professionals in the field will recognize. A complete rotor core 201 may contain several sub-cores 201A or a single stack of sheets. Reference to a rotor core may refer to several sub-cores 201A or a single stack of sheets. The sheets may be cut into their final shape by a punch and through a die, or they may be cut by a laser or by wire EDM. The rotor core 201 may alternatively be manufactured, e.g.,from a mold formed from sintered, powdered metal and binders under heat and pressure, and also from several sub-cores or from a structure formed from a single mold. As in . Fig. As shown in Figure 1, the stator, according to a non-restrictive exemplary embodiment, is arranged concentrically around the rotor 12R, such that the rotor 12R is enclosed by the stator 12S. According to such an embodiment, the air gap G is a radial air gap, and the electric working machine 12 embodies a radial flux working machine. However, other embodiments of rotating electric working machines can be realized in which the relative positions of the rotor 12R and the stator 12S are reversed (e.g., with an inner stator) or the air gap is, for example, axial. For illustration, the embodiment of [Figure 1] is shown here. Fig. 1, in which the rotor 12R is located radially inside the stator 12S, is described without limiting the design to such a configuration.

[0032] The stator 12S from Fig. 1 may contain radially projecting stator teeth extending inwards from a cylindrical stator core, as in Fig. Figure 5 shows that the stator teeth extend from the stator core towards the rotor 12R. The inner surface of the stator 12S is the radially innermost surface of the stator teeth that face or are opposite the outer circumferential surface 205 of the rotor 12R at a distance, in accordance with Fig. 1. to form the air gap G. Adjacent stator teeth are separated from each other by a corresponding stator slot, which is recognized by average experts in the field. The stator slots enclose electrical conductors, typically copper wires, copper rods, or hairpin conductors. Such conductors together form stator windings. When the stator windings are successively driven by a multiphase output voltage from the TPIM 28, which is located in Fig. As shown in Figure 1, when excited, a rotating stator magnetic field is generated. Stator magnetic poles, formed from the resulting rotating stator magnetic field, interact with rotor poles to rotate the rotor 12R around the axis of rotation 203 of the rotor core 201.

[0033] According to the embodiment of the rotating IPM working machine of Fig. 2. The rotor core 201 can contain several slots 207 extending axially through the rotor core 201 between the opposite ends 209 of the rotor core 201. The slots can be oriented axially essentially between the opposite ends 209 of the rotor core, with the actual orientation being oblique, as is known in the art. Viewed along the axis of rotation 203 (approximately in the Fig. 4A-4C) The slots 207 can be elongated by an oblique orientation relative to an actual radial orientation, as is known in the art. Reference here to a radial orientation or a substantially radial orientation of slots or permanent magnets is understood to mean, as is known to those skilled in the art, an actual radial orientation or an oblique radial orientation. According to one embodiment shown in the figures, the slots 207 can be arranged with adjacent pairs in a “V” pattern. According to one embodiment shown in the figures, inner and outer “V” patterns of the slots 207 can be used, with smaller slots 207 closer to the outer circumferential surface 205 of the rotor core 201 and larger slots 207 closer to the axis of rotation 203 of the rotor core 201. According to one embodiment, each slot 207 can contain a permanent magnet arrangement 213.A permanent magnet arrangement 213 can be continuously divided from one end of the rotor core 201 to the other end of the rotor core, or over the axial length of the corresponding slots 207. According to one embodiment, each sub-core 201A can contain a corresponding permanent magnet arrangement 213.

[0034] The permanent magnet assemblies 213 can collectively be referred to here as rotor magnets and can be constructed, for example, from rare-earth magnets such as neodymium and samarium-cobalt magnets and heavy rare-earth magnets (HRE magnets). As used here, HRE magnets are understood to contain, among other things, heavy rare-earth elements (e.g., including dysprosium (Dy), terbium (Tb), and gadolinium (Gd)), whereas non-HRE magnets (NHRE) are understood to do not contain heavy rare-earth elements. The permanent magnet assemblies 213 can be embedded within the corresponding slots 207 within the stack of individual electrical steel sheets of the rotor core 201. The number, type, position, and / or relative orientation of the rotor magnets ultimately influences the magnitude and distribution of the magnetic flux in the ferrous materials of the electric working machine 12.According to one embodiment, the poles of the rotor magnets can be axially oriented between the axial ends 213x (axial x-axis). According to one embodiment, the poles of the rotor magnets can be circumferentially oriented between the circumferentially arranged ends 213y (circumferential Y-axis). According to one embodiment, the poles of the rotor magnets can be radially oriented between the radial ends 213z (radial z-axis).

[0035] The Fig. Figures 3A-3E show various embodiments of the magnet arrangements 213 configured using magnet sections made of different magnetic materials. Any divided magnet arrangement 213 can include at least two magnet sections of different magnetic materials, e.g., a neodymium magnet section and a samarium-cobalt magnet section, or an HRE magnet section and an NHRE magnet section, or a neodymium magnet section, a samarium-cobalt magnet section, and an HRE magnet section. Fig. Figure 3A shows an embodiment of a magnet arrangement 213 which, as shown, is radially subdivided along the radial z-axis. According to the embodiment shown, four magnet sections are shown by way of example, although two or more magnet sections can form any given subdivided magnet arrangement 213. In one embodiment shown, two outer magnet sections 301 and two inner magnet sections 303 are present. According to one embodiment, if, for example, higher operating temperatures are expected at the radial ends 213z than in the center of the magnet arrangement 213, the outer magnet sections 301 can consist of high-resolution magnet sections and the inner magnet sections 303 of low-resolution magnet sections. According to another embodiment, if, for example,higher operating temperatures can be expected in the center of the magnet arrangement 213 than at the radial ends 213z, the outer magnet sections 301 consist of NHRE magnet sections and the inner magnet sections 303 consist of HRE magnet sections.

[0036] Fig. Figure 3B shows an embodiment of a magnet arrangement 213 which, as shown, is subdivided axially along the axial X-axis. According to the embodiment shown, four magnet sections are shown by way of example, although two or more magnet sections can form any given subdivided magnet arrangement 213. In one embodiment shown, two outer magnet sections 305 and two inner magnet sections 307 are present. According to one embodiment, if, for example, higher operating temperatures are expected at the axial ends 213x of the magnet arrangement 213 than in the center, the outer magnet sections 305 can consist of HRE magnet sections and the inner magnet sections 307 of NHRE magnet sections. According to another embodiment, if, for example,higher operating temperatures can be expected in the center of the magnet arrangement 213 than at the axial ends 213x, the outer magnet sections 305 consist of NHRE magnet sections and the inner magnet sections 307 consist of HRE magnet sections.

[0037] Fig. Figure 3C shows an embodiment of a magnet arrangement 213 which, as shown, is subdivided circumferentially along the circumferential Y-axis. According to the embodiment shown, three magnet sections are shown by way of example, although two or more magnet sections can form any given subdivided magnet arrangement 213. In one embodiment shown, two outer magnet sections 321 and one inner magnet section 323 are present. According to one embodiment, if, for example, higher operating temperatures are expected at the circumferential ends 213y of the magnet arrangement 213 than in the center, the outer magnet sections 321 can consist of HRE magnet sections and the inner magnet section 323 of an NHRE magnet. According to another embodiment, if, for example,higher operating temperatures can be expected in the center of the magnet arrangement 213 than at the circumferential ends 213y, the outer magnet sections 321 consist of NHRE magnet sections and the inner magnet section 323 consists of an HRE magnet section.

[0038] Fig. Figure 3D shows an embodiment of a magnet arrangement 213, which, as shown, is subdivided both radially along the radial z-axis and axially along the axial x-axis. According to the embodiment shown, five magnet sections are shown by way of example. In one embodiment, two outer magnet sections 309 are located at the radial ends 213z, two outer magnet sections 311 are located at the axial ends 213x, and one inner magnet section 313 is present. According to one embodiment, if, for example, higher operating temperatures are expected at the radial ends 213z and the axial ends 213x of the magnet arrangement 213 than in the center, the outer magnet sections 309 and 311 can consist of high-resolution magnetic (HRE) magnet sections and the inner magnet section 313 of a low-resolution magnetic (NHRE) magnet section. According to another embodiment, if, for example,higher operating temperatures can be expected in the center of the magnet arrangement 213 than at the radial ends 213z and the axial ends 213x, the outer magnet sections 309 and 311 consist of NHRE magnet sections and the inner magnet section 313 consists of an HRE magnet section.

[0039] Fig. Figure 3E shows an embodiment of a magnet arrangement 213 which, as shown, is subdivided both radially along the radial z-axis and axially along the axial x-axis. According to the embodiment shown, five magnet sections are shown by way of example. In one embodiment shown, two outer magnet sections 315 are located at the radial ends 213z, two outer magnet sections 317 are located at the axial ends 213x, and two inner magnet sections 319 are present. According to one embodiment, if, for example, higher operating temperatures are expected at the radial ends 213z and the axial ends 213x of the magnet arrangement 213 than in the center, the outer magnet sections 315 and 317 can consist of high-resolution magnet sections and the inner magnet sections 319 of low-resolution magnet sections. According to another embodiment, if, for example,higher operating temperatures can be expected in the center of the magnet arrangement 213 than at the radial ends 213z and the axial ends 213x, the outer magnet sections 315 and 317 consist of NHRE magnet sections and the inner magnet sections 319 consist of HRE magnet sections.

[0040] The Fig. Figures 4A-4C show a side view of a rotor containing the rotor core 201, which is in Fig. 2 along the axis of rotation 203 and in relation to the stator 12S and the air gap G. is shown. Fig. Figures 4A-4C show different embodiments of the magnet arrangements 213, which are assembled within the corresponding slots 207 and, as shown, subdivided radially along the corresponding radial z-axis. The smaller slots 207A are shown closer to the outer circumferential surface 205 of the rotor core 201, and the larger slots 207B are shown closer to the axis of rotation 203 of the rotor core 201. Fig. Figures 4A-4C show embodiments of the corresponding magnet arrangements 213, which, as shown, are divided radially along the radial z-axis into both the smaller slots 207A and the larger slots 207B.

[0041] In Fig. Figure 4A includes the magnet arrangement 213A, corresponding to the smaller groove 207A, and the magnet arrangement 213B, corresponding to the larger groove 207B, each comprising, by way of example, three magnet sections. According to one embodiment shown, the magnet arrangement 213A comprises two outer magnet sections 401 and 403 and an inner magnet section 405 within the smaller groove 207A. Similarly, the magnet arrangement 213B comprises two outer magnet sections 407 and 409 and an inner magnet section 411 within the larger groove 207B. According to an embodiment shown with the magnet arrangement 213A, the outer magnet sections 401 and 403 and the inner magnet section 405 can all have rectangular cross-sections and different cross-sectional sizes. The inner magnet section 405 also has a rectangular cross-section. The outer magnetic sections 401 and 403 can be of different sizes and may not be the same size as the inner magnetic section 405.According to an embodiment shown with the magnet arrangement 213B, the outer magnet sections 407 and 409 and the inner magnet section 411 can all have a rectangular cross-section. The two outer magnet sections 407 and 409 can be the same size and smaller than the inner magnet section 411.

[0042] In Fig. Figure 4B includes the magnet arrangement 213A corresponding to the smaller groove 207A, and the magnet arrangement 213B corresponding to the larger groove 207B, also by way of example, three magnet sections. According to one embodiment shown, the magnet arrangement 213A also includes two outer magnet sections 413 and 415 and an inner magnet section 417 within the smaller groove 207A. Similarly, the magnet arrangement 213B includes two outer magnet sections 419 and 421 and an inner magnet section 423 within the larger groove 207B. According to one embodiment shown with the magnet arrangement 213A, the outer magnet sections 413 and 415 and the inner magnet section 417 can all have trapezoidal cross-sections and different cross-sectional sizes. The outer magnet sections 413 and 415 can have different sizes.According to an embodiment shown with the magnet arrangement 213B, the outer magnet sections 419 and 421 and the inner magnet section 411 can all have a trapezoidal cross-section. The two outer magnet sections 419 and 421 can be of the same size.

[0043] In Fig. Figure 4C includes the magnet arrangement 213A, corresponding to the smaller groove 207A, and the magnet arrangement 213B, corresponding to the larger groove 207B, also by way of example, three magnet sections. According to one embodiment shown, the magnet arrangement 213A also includes two outer magnet sections 425 and 427 and an inner magnet section 429 within the smaller groove 207A. Similarly, the magnet arrangement 213B includes two outer magnet sections 431 and 433 and an inner magnet section 435 within the larger groove 207B. According to one embodiment shown with the magnet arrangement 213A, the outer magnet sections 425 and 427 can have a triangular cross-section, and the inner magnet section 429 can have a trapezoidal cross-section. The outer magnet sections 425 and 427 can be of the same size or of different sizes, as shown.According to an embodiment shown with the magnet arrangement 213B, the outer magnet sections 431 and 433 can have a triangular cross-section, and the inner magnet section 435 can have a trapezoidal cross-section. The two outer magnet sections 419 and 421 can be of the same size.

[0044] Fig. Figure 5 shows, for illustration, an embodiment of a magnet arrangement 213A and a magnet arrangement 213B without the rotor core. The magnet arrangement 213A corresponds to a small groove in the rotor core, and the magnet arrangement 213B corresponds to a large groove in the rotor core. The magnet arrangement 213A corresponds to an embodiment of a magnet arrangement that, as shown in Figure B, is subdivided axially along the axial x-axis. The magnet arrangement 213B corresponds to an embodiment of a magnet arrangement that, as shown in Figure A, is subdivided radially along the radial z-axis. In both embodiments of the magnet arrangements 213A and 213B shown, the magnet sections are rectangular in shape; however, it is understood that other shapes, such as trapezoidal and triangular, as described with reference to Fig. 4B and 4C are shown and can be used.

[0045] The terminology used herein serves only to describe certain embodiments and is not intended to be restrictive. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, it shall be understood that the terms "comprises" and / or "encompass," when used in this application, establish the presence of specified features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more further features, integers, steps, operations, element components, and / or groups thereof.

[0046] It is assumed that all numerical values ​​herein are modified by the term "approximately," whether expressly stated or not. For the purposes of this disclosure, ranges may be expressed as from "approximately" one particular value to "approximately" another particular value. The term "approximately" generally refers to a range of numerical values ​​which a person skilled in the art would consider to be equal to the cited numerical value, to have the same function or result, or generally to be sufficiently within the manufacturing tolerances of the cited numerical value. Accordingly, numerical values ​​set forth herein are given in the form of non-limiting examples and may be nominal values, it being understood that actual values ​​may vary according to the environment, design and manufacturing tolerances, age, and other factors.

[0047] When an element, such as a layer, a thin layer, a region, or a substrate, is described as "attached" to another element, it may be located directly adjacent to that other element, or there may also be intervening elements. Conversely, when an element is described as "directly attached" to another element, there are no intervening elements. Therefore, unless explicitly described as "direct," when a relationship between a first and a second element is described in the revelation above, this relationship may be a direct relationship, with no intervening elements between the first and second elements, or it may be an indirect relationship, with one or more intervening elements (either spatial or functional) between the first and second elements.

[0048] One or more steps in a process may be performed in different sequences (or overlapping in time) without altering the principles of this disclosure. Although each of the embodiments above has been described with certain features, one or more of these features described with respect to any embodiment of the disclosure may also be implemented in any of the other embodiments and / or combined with its features, even if this combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with each other remain within the scope of protection of this disclosure.

[0049] Unless otherwise defined, technical and scientific terms used herein have the same meaning as would normally be understood by a person skilled in the field to which this disclosure belongs.

[0050] Unless otherwise specified herein, all testing standards shall be the most recent valid standard as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the testing standard appears.

[0051] While the disclosure described above has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made and elements can be replaced by their equivalents without altering its scope. Furthermore, many adaptations can be made to fit a particular situation or material to the instructions given in the disclosure without deviating from its essential scope. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but includes all embodiments that fall within its scope.

Claims

[1] Electrical machine with internal permanent magnet, comprising: a rotor core having axially opposite ends and a plurality of slots, each slot extending through the rotor core between the axially opposite ends and containing a divided magnet assembly comprising at least one magnet portion of a first magnetic material and at least one magnet portion of a second magnetic material. [2] The internal permanent magnet electric machine according to claim 1, wherein the divided magnet assembly is divided in a radial direction relative to a rotation axis of the rotor core. [3] An inner permanent magnet electric machine according to claim 2, wherein the divided magnet assembly comprises radially outer magnet portions of the first magnetic material at radial ends of the divided magnet assembly, and at least one inner magnet portion of the second magnetic material is located radially between the radially outer magnet portions of the first magnetic material. [4] The internal permanent magnet electric machine according to claim 3, wherein the first magnetic material comprises a heavy rare earth magnet material and the second magnetic material comprises a non-heavy rare earth magnet material. [5] The internal permanent magnet electric machine according to claim 1, wherein the divided magnet assembly is divided in an axial direction relative to a rotation axis of the rotor core. [6] An inner permanent magnet electric machine according to claim 5, wherein the divided magnet assembly comprises axially outer magnet portions of the first magnetic material at axial ends of the divided magnet assembly, and at least one inner magnet portion of the second magnetic material is located axially between the axially outer magnet portions of the first magnetic material. [7] The internal permanent magnet electric machine according to claim 6, wherein the first magnetic material comprises a heavy rare earth magnet material and the second magnetic material comprises a non-heavy rare earth magnet material. [8] The internal permanent magnet electric machine according to claim 1, wherein the divided magnet assembly is divided in a circumferential direction relative to a rotation axis of the rotor core. [9] The internal permanent magnet electric machine according to claim 1, wherein the divided magnet assembly includes magnetic poles oriented in an axial direction relative to a rotational axis of the rotor core. [10] The internal permanent magnet electric machine according to claim 1, wherein the divided magnet assembly includes magnetic poles oriented in a radial direction relative to a rotational axis of the rotor core.

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