Motor rotor and permanent magnet motor

Abstract

The motor rotor comprises a rotor iron core, the rotor iron core comprises a plurality of magnetic steel grooves formed in the radial direction of the rotor iron core and magnetic pole units located between the adjacent magnetic steel grooves, the magnetic steel grooves are evenly distributed in the circumferential direction of the rotor iron core and arranged at intervals, and open grooves are formed in the positions, close to the outer circle of the rotor iron core, of the magnetic steel grooves; the adjacent magnetic pole units are arranged at the slot at intervals, and the outer arc, close to the slot, of each magnetic pole unit is provided with a shaping part with a missing block characteristic. The magnetic flux leakage of the magnetic steel can be reduced, the utilization rate of the magnetic steel is improved, and the cogging torque and the torque pulsation of the motor are reduced through the modification structure of the rotor.

Description

Technical Field

[0001] This application relates to the technical field of permanent magnet motors, and particularly relates to a motor rotor and a permanent magnet motor. Background Art

[0002] Due to advantages such as simple structure, high efficiency, high power density, and high torque density, permanent magnet synchronous motors are widely used in rail transit, aerospace, wind power generation, and household appliance fields. Traditional permanent magnet synchronous motors often adopt surface-mounted or built-in rotor structures. Among them, in order to improve the power density and torque density of the motor, permanent magnet motors often adopt a tangential magnetization structure to increase the air-gap magnetic flux to increase power.

[0003] Please refer to Figure 1 , Figure 1 which is the tangential magnetization rotor core structure in the prior art. This structure has relatively serious magnetic leakage and low utilization rate of permanent magnets; at the same time, the cogging torque and torque ripple are relatively large, affecting the performance of the motor.

[0004] Therefore, in view of the above technical problems, how to improve the utilization rate of magnetic steel and reduce torque ripple is a technical problem that needs to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this application is to provide a motor rotor that can reduce the magnetic leakage of magnetic steel, improve the utilization rate of magnetic steel, and reduce the cogging torque and torque ripple of the motor through the modified structure of the rotor.

[0006] To achieve the above purpose, this application provides a motor rotor, including a rotor core. The rotor core includes a plurality of magnetic steel slots radially opened thereon and pole units located between adjacent magnetic steel slots. The plurality of magnetic steel slots are evenly distributed and spaced along the circumferential direction of the rotor core. A slot is provided at the outer circle of the rotor core near the magnetic steel slots, so that adjacent pole units are spaced at the slot. Each pole unit is provided with a modified part with a missing block feature on the outer arc near the slot.

[0007] Preferably, the modified parts are symmetrically distributed on both sides of the pole unit with respect to the axis of symmetry of the pole unit. The outer arc of the pole unit between the modified parts is an unmodified part;

[0008] In any one of the pole units, the central angle of the first sector area with the unmodified part as the sector arc side and the radius of the rotor core as the sector radius is α; the central angle of the second sector area of the rotor core occupied by each pole unit is β, and the unmodified ratio γ = α / β, and γ takes a value between 0.45 and 0.6; the number of pole units n×β = 360°.

[0009] Preferably, the part of the magnetic pole unit corresponding to the modified part is a planar structure. One side of the planar structure starts from the junction of the modified part and the unmodified part, and the other side inclines towards the inner side of the rotor core and terminates at the junction of the magnetic pole unit and the slot. The modification depth H of the modified part is 0.5 - 1.2 times the air gap of the motor.

[0010] Among them, the modification depth H is the distance between the junction of the magnetic pole unit and the slot and the outer arc or outer arc contour of the rotor core in the radial direction of the rotor core.

[0011] Preferably, the magnet slot is a rectangular slot, and the center line of the magnet slot coincides with the radius of the rotor core.

[0012] Preferably, a magnet adapted to the magnet slot is provided in the magnet slot. A support structure for supporting the inner diameter end of the magnet is arranged on one side of the magnet slot facing the central axis of the rotor core. The slot width is smaller than the magnet slot width to form a convex structure on the magnetic pole unit for abutting against the outer diameter end of the magnet.

[0013] Preferably, the support structure includes rectangular protrusions. The two rectangular protrusions are correspondingly arranged on two adjacent magnetic pole units and are spaced apart. A magnetic isolation slot is formed on the rotor core on one side of the rectangular protrusion facing the central axis of the rotor core.

[0014] Preferably, the number of the magnetic isolation slots is the same as that of the magnet slots and they correspond one by one. A magnetic isolation bridge for supporting the magnetic pole unit is arranged between adjacent magnetic isolation slots. The magnetic isolation bridge is arranged along the radial direction of the rotor core, and the thickness of the magnetic isolation bridge is 0.9 - 1.3 mm.

[0015] Preferably, the support structure includes stepped protrusions arranged on both sides of the bottom of the magnet slot. In the direction of approaching the central axis of the rotor core along the radial direction of the rotor core, the distance between the two stepped protrusions decreases.

[0016] Preferably, there is a stepped surface of the stepped protrusion abutting against the magnet, and a magnetic isolation slot recessed towards the central axis of the rotor core is formed between the two stepped protrusions.

[0017] A permanent magnet motor includes a motor rotor, and the motor rotor is the motor rotor described above.

[0018] Compared with the above background art, the present application reduces the magnetic leakage at the outer diameter end of the permanent magnet greatly by providing a slot near the outer circle of the rotor core, thereby improving the utilization rate of the permanent magnet. At the same time, a profiling operation is carried out on the outer circle of the rotor core, that is, a profiling part with a notch feature is provided on the outer arc of the magnetic pole unit near the slot. Thus, by changing the ratio of the profiled part to the unprofiled part of the rotor core, the cogging torque and torque ripple of the motor are adjusted. Furthermore, when the cogging torque and torque ripple of the motor are minimized, the ratio of the profiled part to the unprofiled part of the rotor core is obtained to reduce the cogging torque and torque ripple of the motor as much as possible and improve the performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0020] Figure 1 Schematic diagram of the rotor core structure in the prior art;

[0021] Figure 2 Schematic diagram of the first rotor core structure provided by the embodiment of the present application;

[0022] Figure 3 For Figure 2 Partial structure schematic diagram of the rotor core in;

[0023] Figure 4 Schematic diagram of the magnetic leakage magnetic circuit structure of the first rotor core provided by the embodiment of the present application;

[0024] Figure 5 For Figure 3 Partial enlarged structure schematic diagram in;

[0025] Figure 6 Schematic diagram of the matching structure of the first rotor core and the permanent magnet provided by the embodiment of the present application;

[0026] Figure 7 Schematic diagram of the second rotor core structure provided by the embodiment of the present application;

[0027] Figure 8 Schematic diagram of the magnetic leakage magnetic circuit structure of the second rotor core provided by the embodiment of the present application;

[0028] Figure 9 Schematic diagram of the matching structure of the second rotor core and the permanent magnet provided by the embodiment of the present application;

[0029] Figure 10 It is a curve graph showing the change of cogging torque with the unmodified ratio γ provided by the embodiment of the present application;

[0030] Figure 11 It is a curve graph showing the change of torque ripple with the unmodified ratio γ provided by the embodiment of the present application;

[0031] Figure 12 It is a curve graph showing the change of torque ripple with the modification depth H provided by the embodiment of the present application;

[0032] Figure 13 It is a curve graph showing the change of cogging torque with the modification depth H provided by the embodiment of the present application;

[0033] Figure 14 It is a comparison graph of the cogging torque of the existing scheme, the first rotor core, and the second rotor core;

[0034] Figure 15 It is a comparison graph of the average torque of the existing scheme, the first rotor core, and the second rotor core.

[0035] In the figure:

[0036] 1 - Rotor core; 11 - Pole unit; 111 - Modified part; 112 - Plane structure; 113 - Unmodified part; 12 - Magnet slot; 13 - Slotting; 14 - Rectangular protrusion; 15 - Magnetic isolation slot; 16 - Magnetic isolation bridge; 17 - Stepped protrusion; 18 - Weight reduction hole;

[0037] 2 - Magnet. Specific implementation manner

[0038] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0039] It should be noted that in this embodiment, the orientation or positional relationship indicated by "up", "down", "front", "back", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, "first", "second", "third", "fourth" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0040] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0041] like Figure 2 As shown, in this embodiment, a motor rotor is provided, the motor rotor includes a rotor core 1, the rotor core 1 includes a plurality of magnetic steel slots 12 extending along its radial direction and magnetic pole units 11 located between adjacent magnetic steel slots 12, and the plurality of magnetic steel slots 12 are evenly distributed along the circumference of the rotor core 1 and arranged at intervals. In the related art, the plurality of magnetic pole units 11 are also evenly distributed along the circumference of the rotor core 1. Generally speaking, the magnetic pole units 11 of the rotor core 1 are eight poles, ten poles, fourteen poles, sixteen poles, etc., that is, the number of corresponding magnetic pole units 11 is eight, ten, fourteen, and sixteen, respectively.

[0042] In some embodiments, a slot 13 is provided near the outer circumference of the rotor core 1 in the magnetic steel slot 12. The arrangement of the slot 13 allows adjacent magnetic pole units 11 to be spaced apart at the slot 13, thereby greatly reducing magnetic leakage on the outside of the magnetic steel 2 and improving the utilization rate of the magnetic steel 2.

[0043] In addition, please refer to Figure 3 In the present application, a modified portion 111 is provided on the outer arc of the magnetic pole unit 11 near the slot 13, and the modified portion 111 specifically has a missing block feature. Specifically, the missing block feature means that on the basis of the original outer circle of the rotor core 1 being an arc surface, the modified portion 111 is set to a missing block feature by cutting, stamping, etc., or the missing block feature is formed on the arc surface of the outer circle of the rotor core 1 by a mold or other processing technology when processing the rotor core 1.

[0044] That is to say, the missing block feature is relative to the prior art in which the outer circle of the rotor core 1 is an arc surface, so that the modified portion 111 forms a missing block structure that is offset to the central axis of the rotor core 1. Correspondingly, the pole unit 11 without the missing block feature is an unmodified structure. Thus, by changing the ratio of the modified portion 111 to the unmodified portion 113 of the rotor core 1, the motor cogging torque and torque pulsation are adjusted, and then the ratio of the modified portion 111 to the unmodified portion 113 of the rotor core 1 is obtained when the motor cogging torque and torque pulsation are minimized, so as to reduce the motor cogging torque and torque pulsation as much as possible and improve the performance of the motor.

[0045] For further information, please refer to Figure 3, for each magnetic pole unit 11, the modified parts 111 are symmetrically distributed on both sides of the magnetic pole unit 11 with respect to the axis of symmetry of the magnetic pole unit 11. Then, the outer arc of the magnetic pole unit 11 located between the modified parts 111 is the unmodified part 113. In the same rotor core 1, the structures of each magnetic pole unit 11 are the same. Therefore, one of the magnetic pole units 11 will be taken as an example in this embodiment for introduction.

[0046] In a magnetic pole unit 11, since the outer circle of the magnetic pole unit 11 is modified, the position corresponding to the modified part 111 is different from the original arc position and shape, while the position corresponding to the unmodified part 113 is the same as the original arc position and shape. Here, the central angle of the first sector area with the unmodified part 113 as the sector arc side and the radius of the rotor core 1 as the sector radius is denoted as α; the central angle of the second sector area occupied by each magnetic pole unit 11 in the rotor core 1 is denoted as β, and the positioning γ = α / β is the unmodified ratio, that is, the ratio of the unmodified angle of the rotor to the modified angle.

[0047] Please refer to Figure 10 and Figure 11 , Figure 10 is the curve graph of the cogging torque of the motor varying with the unmodified ratio γ, Figure 11 is the curve graph of the torque ripple varying with the unmodified ratio γ. It can be seen that the cogging torque and the torque ripple first decrease and then increase with the increase of γ. Through simulation calculation, when the unmodified ratio γ is between 0.45 and 0.6, the cogging torque and the torque ripple of the motor are the smallest.

[0048] It should be noted that the above-mentioned second sector area refers to the sector area of the rotor core 1 occupied by each magnetic pole unit 11, and multiple magnetic pole units 11 evenly divide the rotor core 1 circumferentially into multiple corresponding sector areas. The central angles of the multiple sector areas together form 360° of the rotor core 1, that is, the number n of the magnetic pole units 11 × β = 360°.

[0049] In addition, please refer to Figure 5 , the part of the magnetic pole unit 11 corresponding to the modified part 111 is a planar structure 112. One side of the planar structure 112 starts from the junction of the modified part 111 and the unmodified part 113, and the other side inclines towards the inner side of the rotor core 1 and terminates at the junction of the magnetic pole unit 11 and the slot 13, thus forming a modified structure with a missing block feature.

[0050] Among them, the modified depth H is the distance between the junction of the magnetic pole unit 11 and the slot 13 and the outer arc or the outer arc contour of the rotor core 1 in the radial direction of the rotor core 1, that is, Figure 5 the H in Figure 12 and Figure 13 , Figure 12The figure shows the curve of the cogging torque of the motor varying with the modification depth H. Figure 13 The figure shows the curve of the torque ripple varying with the modification depth H. It can be seen that the cogging torque and the torque ripple first decrease and then increase with the increase of H. Through simulation calculation, when H takes a value between 0.5 and 1.2 times the air gap of the motor, the cogging torque and the torque ripple of the motor are the smallest.

[0051] In some embodiments, after determining the unmodified ratio γ and the modification depth H, at the junction of the modified part 111 and the unmodified part 113 (the intersection of the arc edge and the radius of the first sector area), a straight line is connected at the modification depth H, thus forming Figure 5 the planar structure 112 in, making the outer circle of the rotor core 1 form an uneven air gap, making the air gap magnetic density waveform more sinusoidal, thereby reducing the cogging torque and the torque ripple.

[0052] In some embodiments, the magnet slot 12 can be a rectangular slot, and the center line of the magnet slot 12 coincides with the radius of the rotor core 1. On this basis, combining Figure 3 it can be known that for a second sector area, it not only includes the area where the magnetic pole unit 11 is located, but also includes the area between the center lines of the magnet slots 12 on both sides of the magnetic pole unit 11; and so on, thus forming the circumferential structure of the rotor core 1 through multiple second sector areas.

[0053] Of course, the shape of the magnet slot 12 includes but is not limited to a rectangular slot, which will not be elaborated here one by one, and all fall within the protection scope of this application.

[0054] A magnet 2 adapted to it is provided in the magnet slot 12. Please refer to Figure 6 and Figure 9 , a support structure for supporting the inner diameter end of the magnet 2 is provided on the side of the magnet slot 12 facing the central axis of the rotor core 1. The width of the slot 13 is smaller than the width of the magnet slot 12, so as to form a convex structure on the magnetic pole unit 11 that abuts against the outer diameter end of the magnet 2, so that the magnet 2 is more firmly supported and the relative position of the magnet 2 is prevented from shifting, resulting in performance degradation.

[0055] In the first implementation manner, the support structure includes a rectangular protrusion 14. Please refer to Figure 2 , two rectangular protrusions 14 are correspondingly provided on two adjacent magnetic pole units 11, and the two rectangular protrusions 14 are arranged at intervals. A magnetic isolation slot 15 is provided on the rotor core 1 on the side of the rectangular protrusion 14 facing the central axis of the rotor core 1.

[0056] The rectangular protrusion 14 can directly abut against the inner diameter end of the magnet 2, and the convex structure formed by the slot 13 abuts against the outer diameter end of the magnet 2, thus forming a stable clamping structure. It should be noted that the inner diameter end and the outer diameter end of this application respectively refer to the end facing the central axis of the rotor core 1 and the end facing the outer arc of the rotor core 1.

[0057] The number of the magnetic isolation grooves 15 is the same as that of the magnetic steel grooves 12 and they correspond to each other one by one. A magnetic isolation bridge 16 for supporting the magnetic pole unit 11 is arranged between adjacent magnetic isolation grooves 15. Please refer to Figure 2 , the magnetic isolation bridge 16 is arranged along the radial direction of the rotor core 1. At the same time, the magnetic isolation grooves 15 on both sides of the magnetic isolation bridge 16 are symmetrically arranged with respect to the magnetic isolation bridge 16.

[0058] Considering that the thickness of the magnetic isolation bridge 16 will affect the mechanical strength of the rotor and the degree of magnetic leakage inside the magnetic steel 2, the thicker the magnetic isolation bridge 16, the better the mechanical strength, but the more magnetic leakage of the magnetic steel 2. Through optimized calculation, when the thickness of the magnetic isolation bridge 16 is between 0.9 - 1.3 mm, the mechanical strength and anti-magnetic leakage performance of the rotor are better.

[0059] In the second embodiment, the support structure includes stepped protrusions 17 arranged on both sides of the bottom of the magnetic steel groove 12. Please refer to Figure 7 , along the radial direction of the rotor core 1 and approaching the central axis direction of the rotor core 1, the distance between the two stepped protrusions 17 decreases. There is a stepped surface of the stepped protrusion 17 in contact with the magnetic steel 2, and a magnetic isolation groove 15 recessed towards the central axis direction of the rotor core 1 is formed between the two stepped protrusions 17.

[0060] Different from the first embodiment and the prior art, this embodiment changes the magnetic circuit structure of the magnetic leakage inside the magnetic steel 2. Specifically, please refer to Figure 4 and Figure 8 , Figure 4 is a schematic diagram of the magnetic leakage magnetic circuit structure of the rotor core 1 in the first embodiment, Figure 8 is a schematic diagram of the magnetic leakage magnetic circuit structure of the rotor core 1 in the second embodiment. In this embodiment, the magnetic leakage magnetic circuit path of the magnetic steel 2 is changed to pass through the bottom of the magnetic isolation groove 15, so that the magnetic isolation bridge 16 part in the existing scheme and the previous embodiment only bears the mechanical strength function, thereby reducing the width of the magnetic leakage magnetic circuit without affecting the mechanical strength, and further reducing the magnetic leakage and improving the utilization rate of the magnetic steel 2.

[0061] In addition, in this embodiment, a weight reduction hole 18 is opened on the rotor core 1 between adjacent magnetic isolation grooves 15 and on the side of the rotor core 1 biased towards the central axis. Please refer to Figure 7 , the shape and size of the weight reduction hole 18 can be adjusted or removed as the size changes, and this part does not affect the performance of the motor. To a certain extent, the weight reduction hole 18 can also be used as a magnetic isolation hole and assist the magnetic isolation groove 15 in guiding magnetic flux, blocking magnetic flux, improving the performance of the motor, etc.

[0062] Compared with the prior art, please refer to Figure 14 and Figure 15 , Figure 14 is a comparison diagram of the cogging torque of the existing scheme, the first rotor core, and the second rotor core;Figure 15 It is a comparison chart of the average torques of the existing solution, the first rotor core, and the second rotor core. The two implementation manners of the present application can greatly reduce the magnetic leakage of the permanent magnet 2, improve the utilization rate of the permanent magnet 2, and at the same time, through the special modified structure of the rotor core 1, greatly reduce the cogging torque and torque ripple of the motor.

[0063] The present application also provides a permanent magnet motor, which includes necessary components such as a motor rotor and a motor stator, which will not be elaborated here and can be specifically referred to the prior art. The motor rotor is the motor rotor in the above embodiment. Therefore, this permanent magnet motor can also reduce the magnetic leakage of the permanent magnet 2, improve the utilization rate of the permanent magnet 2, and reduce the cogging torque and torque ripple of the motor, etc.

[0064] It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0065] Specific examples are used in this article to elaborate on the principle and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A motor rotor, characterized in that, It includes a rotor core (1), the rotor core (1) includes a plurality of magnet slots (12) opened along its radial direction and pole units (11) located between adjacent magnet slots (12), the plurality of magnet slots (12) are evenly distributed and spaced along the circumferential direction of the rotor core (1), a slotted opening (13) is provided at the outer circle of the rotor core (1) close to the magnet slots (12), so that adjacent pole units (11) are spaced at the slotted opening (13), and a profiling part (111) with a notch feature is provided on the outer arc of each pole unit (11) close to the slotted opening (13).

2. The motor rotor according to claim 1, characterized in that, The profiling parts (111) are symmetrically distributed on both sides of the pole unit (11) with respect to the axis of symmetry of the pole unit (11), and the outer arc of the pole unit (11) located between the profiling parts (111) is an unprofiled part (113); In any one of the pole units (11), the central angle of the first sector area with the unprofiled part (113) as the sector arc side and the radius of the rotor core (1) as the sector radius is α; the central angle of the second sector area occupied by each pole unit (11) of the rotor core (1) is β, and the unprofiled ratio γ = α / β, and the value of γ is between 0.45 and 0.6; the number n of the pole units (11) × β = 360°.

3. The motor rotor according to claim 2, wherein, The part of the pole unit (11) corresponding to the profiling part (111) is a planar structure (112), one side of the planar structure (112) starts from the junction of the profiling part (111) and the unprofiled part (113), and the other side inclines towards the inner side of the rotor core (1) and terminates at the junction of the pole unit (11) and the slotted opening (13), and the profiling depth H of the profiling part (111) is 0.5 - 1.2 times the air gap of the motor; Among them, the profiling depth H is the distance between the junction of the pole unit (11) and the slotted opening (13) and the outer arc or the outer arc contour of the rotor core (1) in the radial direction of the rotor core (1).

4. The motor rotor according to claim 1, characterized in that, The magnet slot (12) is a rectangular slot, and the center line of the magnet slot (12) coincides with the radius of the rotor core (1).

5. The motor rotor according to any one of claims 1-4, characterized in that A magnet (2) adapted to it is provided in the magnet slot (12), a support structure for supporting the inner diameter end of the magnet (2) is provided on one side of the magnet slot (12) facing the central axis of the rotor core (1), and the width of the slotted opening (13) is smaller than the width of the magnet slot (12) to form a convex structure on the pole unit (11) for abutting against the outer diameter end of the magnet (2).

6. The motor rotor according to claim 5, characterized in that, The support structure includes rectangular protrusions (14), the two rectangular protrusions (14) are correspondingly arranged on adjacent two pole units (11), and the two rectangular protrusions (14) are spaced, and a magnetic isolation slot (15) is opened on the rotor core (1) on the side of the rectangular protrusion (14) facing the central axis of the rotor core (1).

7. The motor rotor according to claim 6, characterized in that, The magnetic isolation grooves (15) are equal in number to and correspond one-to-one with the magnet grooves (12). A magnetic isolation bridge (16) for supporting the magnetic pole unit (11) is provided between adjacent magnetic isolation grooves (15). The magnetic isolation bridge (16) is arranged radially along the rotor core (1), and the thickness of the magnetic isolation bridge (16) is 0.9 - 1.3 mm.

8. The motor rotor according to claim 5, characterized in that The support structure includes stepped protrusions (17) provided on both sides of the bottom of the magnet groove (12). Along the direction of the radial of the rotor core (1) approaching the central axis of the rotor core (1), the distance between the two stepped protrusions (17) decreases.

9. The motor rotor according to claim 8, characterized in that, One stepped surface of the stepped protrusion (17) abuts against the magnet (2), and a magnetic isolation groove (15) recessed in the direction of the central axis of the rotor core (1) is formed between the two stepped protrusions (17).

10. A permanent magnet motor, comprising a motor rotor, characterized in that, The motor rotor is the motor rotor according to any one of claims 1 - 9.

Images