Variable motor laminations

Abstract

An electric motor having a rotor and a stator, wherein the rotor and / or the stator may include two or more parts, and the torque fluctuations caused by the magnetic field associated with a part of the rotor (or stator) may at least partially offset the torque fluctuations caused by the magnetic field associated with other parts of the rotor (or stator).

Description

Technical Field

[0001] The present disclosure relates to electric motors and discusses methods of reducing ripple in motor torque and reducing cogging torque. Background Art

[0002] The motor operates by rotating the rotor relative to the stator under the influence of the magnetic interaction between the rotor and stator components. When the rotor rotates relative to the stator, the interaction force / torque between the rotor and the stator may change due to changes in the associated magnetic field. One effect on torque involved in relative rotation can be called "cogging torque". Cogging torque can be understood as the torque generated by the interaction between magnets (such as permanent magnets) and slots. In some embodiments, the magnets can be associated with the rotor and the slots can be associated with the stator, and in some embodiments, the magnets can be associated with the stator and the slots can be associated with the rotor. Sometimes, cogging torque can be referred to as positioning torque or "no current" torque. Generally, cogging torque is undesirable and can be associated with motor jitter and torque fluctuations, especially at low speeds. Therefore, it is desirable to reduce the cogging torque of the motor.

[0003] Another effect on torque involved in relative rotation may be referred to as “torque ripple.” Torque ripple may refer to a periodic increase or decrease in the output torque of an electric motor. Summary of the invention

[0004] The present disclosure provides an electric motor having variable motor laminations.

[0005] In a first aspect disclosed herein, a motor rotor is provided, the motor rotor comprising: a rotor comprising a first rotor portion and a second rotor portion and a series of magnets, the first rotor portion comprising: a series of magnet accommodating portions adjacent to the outer edge of the first rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in a stator and distributed around the first rotor portion, thereby achieving relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets having a respective d-axis extending through the magnet and the outer edge of the first rotor portion; the first rotor portion comprising, for each magnet, respective air holes or air barriers symmetrical with respect to the respective d-axis; wherein each air hole or air barrier generates an asymmetric magnetic field of the respective magnet; the second rotor portion comprising: a series of magnet accommodating portions adjacent to the outer edge of the second rotor portion and configured to receive respective magnets, to interact magnetically with a series of coils located in the stator and distributed around the second rotor part, thereby achieving relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets has a respective d-axis, which extends through the outer edge of the magnet and the second rotor part; the second rotor part includes a respective air hole or air barrier for each magnet that is asymmetric relative to the respective d-axis; wherein each air hole or air barrier produces an asymmetric magnetic field of the respective magnet; wherein the first rotor part is arranged in series with the second rotor part, and the magnet receiving portion of the first rotor part corresponds to the magnet receiving portion of the second rotor part; and wherein each of the magnets is located in the magnet receiving portion of the first rotor part and the magnet receiving portion of the second rotor part; wherein during operation, the asymmetry of the magnetic field of the second rotor part causes torque fluctuations, which at least partially offsets the fluctuations of the asymmetry of the magnetic field of the first rotor part.

[0006] In a second aspect disclosed herein, a motor stator is provided, comprising: a first stator part, a second rotor part and a series of coils, the first stator part comprising: a series of winding openings, each winding opening being configured to receive an electric wire to form one of a series of coils wound around teeth of the first stator part; each tooth of the first stator part providing a first stator magnetic field; the second stator part comprising: a series of winding openings, each winding opening being configured to receive an electric wire to form one of a series of coils wound around teeth of the second stator part; each tooth of the second stator part providing a second stator magnetic field; wherein the first stator part is arranged in series with the second stator part, the teeth of the first stator part correspond to the teeth of the second stator part, and the coil of each tooth is made by winding a conductor around the teeth of the first stator part and the corresponding teeth of the second stator part, and during operation, the first stator magnetic field causes a first fluctuation in torque, which at least partially offsets the second fluctuation in torque caused by the second stator magnetic field.

[0007] In a third aspect disclosed herein, an electric motor is provided, the electric motor comprising: a rotor comprising a first rotor portion, a second rotor portion and a series of magnets; and a motor stator comprising a first stator portion, a second stator portion and a series of coils, wherein the first rotor portion comprises: a series of magnet receiving portions, the magnet receiving portions being adjacent to the outer edge of the first rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed around the first rotor portion, thereby achieving relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets having a respective d-axis extending The invention relates to a rotor having a plurality of magnets and a plurality of rotor portions, wherein the plurality of magnets are provided with a plurality of d-axis axes and a plurality of d-axis axes extending through the rotor portion and the plurality of rotor portions. The rotor portion comprises a plurality of magnets and a plurality of coils disposed in the stator and around the rotor portion, wherein the plurality of coils are provided in the stator and the plurality of coils are provided ... an outer edge of a rotor portion; a second rotor portion including, for each magnet, a respective air hole or air barrier that is asymmetric with respect to a respective d-axis; wherein each air hole or air barrier causes an asymmetric magnetic field of a respective magnet; wherein the first rotor portion is arranged in series with the second rotor portion, wherein the magnet receiving portion of the first rotor portion corresponds to the magnet receiving portion of the second rotor portion; and wherein each of the magnets is located within the magnet receiving portion of the first rotor portion and the magnet receiving portion of the second rotor portion; the first stator portion includes: a series of winding openings, each winding opening being configured to receive a wire to form one of a series of coils wound around teeth of the first stator portion; the first stator portion Each tooth of the first stator portion provides a first stator magnetic field; the second stator portion includes: a series of winding openings, each winding opening is configured to receive an electric wire to form one of a series of coils wound around the teeth of the second stator portion; each tooth of the second stator portion provides a second stator magnetic field; wherein the first stator portion is arranged in series with the second stator portion, the teeth of the first stator portion correspond to the teeth of the second stator portion, and the coil of each tooth is made by winding a conductor around the teeth of the first stator portion and the corresponding teeth of the second stator portion; and during operation, the first stator magnetic field causes torque fluctuations, which at least partially offset the torque fluctuations caused by the second stator magnetic field.

[0008] In a first embodiment of the second or third aspect, the teeth of the first stator include a first tooth head, the first tooth head has a first tooth head shape, the teeth of the second stator part include a second tooth head, the second tooth head has a second tooth head shape, the first tooth head and the second tooth head are different from each other, and the difference between the first torque fluctuation and the second torque fluctuation is related to the difference between the first tooth head shape and the second tooth head shape.

[0009] In a second embodiment of the second or third aspect, the teeth of the first stator include a first tooth head, the first tooth head has a first tooth head shape, the teeth of the second stator part include a second tooth head, the second tooth head has a second tooth head shape, the first tooth head and the second tooth head are different from each other, and the difference between the first and second torque fluctuations is related to the difference between the first and second tooth head shapes, and the edge-to-edge width of the first tooth head shape and the second tooth head shape is different.

[0010] In a third embodiment of the second or third aspect, the tooth of the first stator includes a first tooth head, the first tooth head has a first tooth head shape, the tooth of the second stator part includes a second tooth head, the second tooth head has a second tooth head shape, the first and second tooth heads are different from each other, and the difference between the first and second torque fluctuations is related to the difference between the first and second tooth head shapes, and the first tooth head has a face including one or more facets, the second tooth head has a face including one or more facets corresponding to the one or more facets of the first tooth head, and the first tooth head shape and the second tooth head shape are different in the surface area of ​​the facets of the first tooth head and the corresponding facets of the second tooth head.

[0011] In a fourth embodiment of the third aspect, the asymmetry of the magnetic field in the first rotor portion and the second rotor portion is caused only by the asymmetry in the air holes.

[0012] In a fifth embodiment of the third aspect, the asymmetry of the magnetic field in the first rotor part and the second rotor part is caused only by the asymmetry in the gas barrier.

[0013] In a first embodiment of the first aspect, the asymmetry of the magnetic field in the first rotor part and the second rotor part is caused only by the asymmetry in the air holes.

[0014] In a second embodiment of the first aspect, the asymmetry of the magnetic field in the first rotor part and the second rotor part is caused only by the asymmetry in the gas barrier.

[0015] In a third embodiment of the first aspect, the motor rotor further includes a third rotor portion, which includes: a series of magnet accommodating portions, which are adjacent to the outer edge of the third rotor portion and are configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed around the third rotor portion, thereby achieving relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets has a respective d-axis that extends through the magnet and the outer edge of the first rotor portion; wherein the third rotor portion is aligned with the first rotor portion and the second rotor portion, and wherein the magnet accommodating portions of the third rotor portion correspond to the magnet accommodating portions of the first rotor portion and the second rotor portion; and wherein each of the magnets is located within the magnet accommodating portions of the first, second and third rotor portions.

[0016] In a fourth embodiment of the first aspect, the motor rotor further comprises a third rotor portion, the third rotor portion comprising: a series of magnet receptacles adjacent to an outer edge of the third rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed around the third rotor, thereby enabling relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets having a respective d-axis extending through the magnet and the outer edge of the first rotor portion. wherein the third rotor portion is aligned with the first and second rotor portions, and the magnet receptacles of the third rotor portion correspond to the magnet receptacles of the first and second rotor portions; and wherein each of the magnets is located within the magnet receptacles of the first, second and third rotor portions, and the third rotor portion comprises respective air holes or air barriers for each magnet that are asymmetric with respect to the respective d-axis; wherein each air hole or air barrier generates an asymmetric magnetic field for the respective magnet, and during operation, the asymmetry of the magnetic field of the third rotor portion results in torque fluctuations that at least partially offset the fluctuations of the asymmetry of the magnetic field of the first and / or second rotor portions.

[0017] In a seventh embodiment of the third aspect, the motor rotor also includes a third rotor portion, which includes: a series of magnet accommodating portions, which are adjacent to the outer edge of the third rotor portion and are configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed around the third rotor portion, thereby achieving relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets has a respective d-axis that extends through the magnet and the outer edge of the first rotor portion; wherein the third rotor portion is aligned with the first rotor portion and the second rotor portion, and the magnet accommodating portion of the third rotor portion corresponds to the magnet accommodating portion of the first rotor portion and the second rotor portion; and wherein each of the magnets is located within the magnet accommodating portions of the first, second and third rotor portions.

[0018] In an eighth embodiment of the third aspect, the motor rotor further comprises a third rotor portion, the third rotor portion comprising: a series of magnet receptacles adjacent to an outer edge of the third rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed around the third rotor portion to achieve relative rotation of the rotor and the stator when the coils are energized during operation; each of the magnets having a respective d-axis extending through the magnet and the outer edge of the first rotor portion. wherein the third rotor portion is aligned with the first rotor portion and the second rotor portion, and the magnet receptacles of the third rotor portion correspond to the magnet receptacles of the first rotor portion and the second rotor portion; and wherein each of the magnets is located within the magnet receptacles of the first, second and third rotor portions, and the third rotor portion comprises, for each magnet, respective air holes or air barriers that are asymmetric with respect to the respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field of the respective magnet, and during operation, the asymmetry of the magnetic field of the third rotor portion causes torque fluctuations that at least partially offset the fluctuations of the magnetic field asymmetry of the first rotor portion and / or the second rotor portion.

[0019] In a fourth aspect, an electric motor is provided, comprising a rotor and a stator, wherein the rotor and / or the stator may comprise two or more parts, and torque fluctuations caused by a magnetic field associated with one part of the rotor (or stator) may at least partially offset torque fluctuations caused by a magnetic field associated with other parts of the rotor (or stator).

[0020] The motor according to the embodiment of the present disclosure may reduce the fluctuation in motor torque and the cogging torque through variable motor laminations. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a diagram of an embodiment of a rotor and a stator of an electric motor.

[0022] Figure 2 is a diagram of an embodiment of a rotor and a stator of an electric motor.

[0023] Figure 3 is a diagram of an embodiment of a rotor and a stator of an electric motor.

[0024] Figure 4 is a diagram of an embodiment of a stator with variable laminations.

[0025] Figure 5 is a diagram of an embodiment of a magnet in a rotor.

[0026] Figure 6 is a diagram of an embodiment of a magnet in a rotor.

[0027] Figure 7 An embodiment of a symmetrical toothing of a stator is shown.

[0028] Figure 8 and Fig. 9 An embodiment of an asymmetric tooth of a stator is shown.

[0029] Fig.10 is a graph of modeled torque ripple versus rotor position for an embodiment of a rotor in an electric motor.

[0030] Fig.11 is a graph of modeled cogging torque versus rotor position for an embodiment of a rotor in an electric motor.

[0031] Fig.12 Embodiments are shown having stator teeth with different edge-to-edge widths.

[0032] Fig.13 and Fig.14 An embodiment of a stator tooth having a tooth surface including facets is shown. DETAILED DESCRIPTION

[0033] In the following description, many specific details are set forth to clearly describe the various specific embodiments disclosed herein. However, those skilled in the art will appreciate that the presently claimed invention may be implemented without any of the specific details discussed below. In other cases, well-known features are not described in order to avoid obscuring the present invention.

[0034] Rotating electric motors, including permanent magnet motors, can operate through magnetic interactions between a rotor located within a stator. The description provided herein will be based on an interior permanent magnet motor, however the teachings provided may also be directed to embodiments oriented as surface permanent magnet motors. Additionally, the description provided herein will be based on magnets on or within a rotor surrounded by a stator, the stator may include coils and include slots, however the teachings provided may also be directed to embodiments where the magnets are located on or within a stator and the rotor includes coils and / or slots.

[0035] like Figure 1 As shown, the motor 11 may include a rotor 12 surrounded by a stator 13. The rotor may include a series of magnets 21 disposed near an outer edge 28 of the rotor. The magnets may be located in receptacles 22 and may have any suitable shape. Figure 1 In other embodiments, the magnets may be bar-shaped, rectangular, "U"-shaped, combinations of these shapes, and combinations with "V"-shaped magnets. Each magnet may also be a single piece or multiple pieces, wherein Figure 1The magnets are two pieces, each with its polarity pointing in the same direction. In many motor embodiments, a series of magnets may have alternating polarity, with one magnet having its polarity pointing in a first direction and the next magnet traveling around the rotor having its polarity pointing in the opposite direction.

[0036] The magnet 21 may be located in the receiving portion 22. The magnet receiving portion 22 may be shaped so that the magnet 21 may be located in the receiving portion 22. The magnet receiving portion 22 may be shaped to include one or more air barriers 25, for example, at the end of the magnet 21 or along the surface of the magnet 21, the air barriers 25 providing an air gap between the magnet 21 located inside the receiving portion 22 and the inner wall of the receiving portion 22. In some embodiments, there may be multiple air barriers 25 in the receiving portion 22. Figure 1 In the embodiment, the receiving portion 22 has three air barriers 25 , wherein there is an air barrier 25 at each opposite end of the first part and the second part of each magnet 21 , and there is an receiving portion 22 between adjacent ends of the first part and the second part of each magnet 21 .

[0037] The rotor may be of any suitable design. Figure 1 The rotor 12 shown in FIG. 1 is shown having a stator 13 including a series of inwardly oriented teeth 14 having slots, and winding openings 15 located between adjacent teeth 14 and configured for winding a coil on each tooth.

[0038] The motor is operated by sequentially energizing the coils, which then generate an electromagnetic field that interacts with the rotor's magnets to apply torque to the rotor and cause the rotor to rotate relative to the stator. As the motor turns, the teeth (and corresponding coils) interact magnetically with nearby magnets, and in some embodiments, this interaction can vary, resulting in fluctuations in the torque provided by the motor. In some embodiments, increasing the number of teeth and magnets can reduce the magnitude of the fluctuations. However, other methods of reducing fluctuations are also desirable.

[0039] In one method of reducing torque fluctuations, as in Figure 1 and Figure 5 As shown in FIG. 1 , asymmetry may be provided in the first portion of the rotor 12a by providing, for example, at each of the magnets 21, an air hole 24 in the first portion of the rotor 12a that is asymmetric with respect to the magnet's d-axis 23 extending through the magnet and the outer edge of the rotor bore to provide unequal influence on the magnetic field on either side of the d-axis 23. Figure 1 and Figure 5 In the embodiment of FIG. 1 , the air hole 24 is located on the left side of the d-axis 23. It should be noted that Figure 1 and Figure 5In the embodiment, the air hole 24 is asymmetric with respect to the d-axis 23 because the air hole 24 is located on only one side of the d-axis 23. In other embodiments, the asymmetry with respect to the air hole 24 or a series of air holes 24 with respect to each magnet can be achieved by positioning the air hole 24 or a series of air holes to provide an unequal effect on the magnetic field on either side of the d-axis 23, for example by positioning the air hole 24 or a series of air holes 24 on either side of the d-axis 23 in an unequal manner. Figure 1 and Figure 5 In FIG. 2 , only a single pore is shown on one side of the d-axis 23. Figure 2 and Figure 6 As shown, the first rotor portion 12a can then be mated with the second rotor portion 12b. Figure 2 and Figure 6 In, through Figure 2 and Figure 6 The air hole 24 is arranged to the right of the d-axis 23 of the magnet 24 in the first rotor part 12a to produce an asymmetry opposite to the magnetic field generated by the magnet 24 of the first rotor part 12a. The size and position of the air hole 24 of the first rotor part 12a and the size and position of the air hole 24 of the second rotor part can be selected so that the asymmetry or distortion of the magnetic field generated by the magnets of the first and second rotor parts cancels each other to reduce Fig.10 The torque fluctuation and Fig.11 The cogging torque shown in .

[0040] In some embodiments of the laminated rotor 12 described herein, the first rotor portion 12a may be arranged in series with the second rotor portion 12b, wherein the two rotor portions are arranged end to end, such that the center lines of the rotor portions are coaxial, and the receptacle 22 of the first rotor portion 12a corresponds to the receptacle 22 of the second rotor portion 12b, thereby allowing each magnet to extend to the receptacle 22 of the first rotor portion 12a and the receptacle 22 of the second rotor portion 12b. In some embodiments, the first rotor portion may be assembled to the second rotor portion, and then the magnet may be slid into the motor receptacle from one end to extend to the receptacle of the first rotor layer and the second rotor layer.

[0041] In some embodiments, there may also be a third rotor layer, such as a rotor layer that lacks the asymmetry of the first and second layers, or a rotor layer that has an asymmetry as described for the first and second layers. In various embodiments, the third rotor layer may be located between the first and second rotor layers, or may be located at one end or the other of the first and second rotor layer assembly.

[0042] In another embodiment of an asymmetric rotor section, an asymmetric air barrier 25 may be provided in the rotor section to provide an asymmetric magnetic field that may be at least partially offset by an asymmetric magnetic field in the second rotor section. In one such embodiment, an air barrier 25 may be added or an existing air barrier 25 may be modified to provide an asymmetric air barrier 25 for each magnet, such as where the air barrier on one side of the d-axis is larger in size than a corresponding air barrier on the other side of the d-axis, or where the air barrier on one side of the d-axis is positioned to have a different effect on the magnetic field than an air barrier on the other side of the d-axis.

[0043] In some embodiments, a combination of asymmetric pores 24 and air barriers 25 may be used, for example, both the asymmetric pores 24 and the asymmetric air barriers 25 are located within the rotor layer, or wherein the asymmetric pores 24 are present in one rotor layer and the asymmetric air barriers are present in a second rotor layer, wherein the first rotor layer and the second rotor layer are combined into a rotor for an electric motor.

[0044] In various embodiments of asymmetric rotor layers, the size and location of the air holes 24 and / or air barriers 25 may be selected to achieve a beneficial reduction in torque ripple and / or cogging torque.

[0045] In some embodiments, asymmetric first and second rotor layers (and optionally third rotor layers) may be used with a stator that does not have the asymmetric features described herein.

[0046] In a second method of reducing torque ripple, a different tooth design may be used in the first stator portion as compared to the second stator portion. In some embodiments where the tooth design is different between the first stator portion and the second stator portion, the teeth in the first stator portion and the second stator portion may have wire-wound tooth portions (tooth bodies) of the same width between the first stator portion and the second stator portion, and the stator portions may be configured so that the tooth bodies of the first portion are aligned with the tooth portions of the second stator portion to facilitate winding the respective aligned teeth of the first stator portion and the second stator portion. In various embodiments, the tooth heads 30 (extending from the tooth bodies 29 toward the rotor in the assembled motor) may have different designs between the first rotor portion and the second rotor portion so that the magnetic field from the first stator portion is different from the magnetic field from the second stator portion to advantageously reduce or substantially eliminate torque ripple in the motor. In some embodiments of different tooth designs, the mass of the tooth head can be varied between the first and second stator portions, or the edge-to-edge width of the tooth head 30 can be varied between the first and second stator portions, or the curvature of the tooth face can be varied between the first and second stator portions, or the shape of the tooth face can be varied between the first and second stator portions, such that the tooth face can be faceted (having flat or curved facets) wherein one or more facets or all facets of the tooth face have different surface areas between corresponding facets of the first stator portion and the second stator portion, or the shape of the tooth head results in a different amount of air being present between the teeth and the rotor of the first stator portion as compared to the second stator portion. In various embodiments of tooth designs such as those discussed herein, the tooth design can be symmetrical or asymmetrical with respect to the tooth axis 27.

[0047] Fig.12 An embodiment of stator teeth having tooth heads with different side-to-side widths is shown, for example, wherein a first tooth that may be associated with one of a first stator portion and a second stator portion is shown in dashed lines, and a second tooth that may be associated with the other of the first stator portion and the second stator portion is shown in solid lines, and the side-to-side dimension 42b of the tooth head of the first tooth is narrower than the side-to-side dimension 42a of the tooth head of the second tooth. Although Fig.12 Symmetric side-to-side width variation is shown, but asymmetric side-to-side variation exists, such as where the width on one side of the central axis is different than the width on the other side of the tooth axis 27. In various embodiments, the asymmetry between the first and second stator portions may be reversed.

[0048] Fig.13 and Fig.14 The different facets of the tooth surface are shown, where Fig.13 The surface area of ​​the central facet 43 (the facet intersecting the tooth axis 27) is greater than Fig.14 In addition, the facets next to the central facet 43 have a Fig.14 The corresponding facets in Fig.14 It is positioned at a more oblique angle relative to the central facet (and tooth axis 27 ) than . Fig.13 and Fig.13 Symmetrical variation of facet surface area is shown, however asymmetric variation of facet surface area is possible, for example the facet area on one side of the tooth axis is different from the corresponding facet area on the opposite side of the tooth axis 27. In various embodiments, the asymmetry between the first and second stator portions may be reversed.

[0049] In some embodiments of asymmetric tooth designs, asymmetry can be provided in one or more or all teeth of the first stator portion by, for example, shaping the tooth surface 28 so that each tooth surface 28 is asymmetric relative to a tooth axis 27 that bisects the tooth 14 at the tooth body 29 to provide unequal effects on the magnetic field on either side of the tooth axis 27. Fig.12 An embodiment of stator teeth having tooth heads with different edge-to-edge widths is shown, for example, wherein a first tooth that may be associated with one of a first stator portion and a second stator portion is shown in dashed lines, and a second tooth associated with the other of the first stator portion and the second stator portion is shown in solid lines, and the edge-to-edge dimension 42b of the tooth head of the first tooth is narrower than the edge-to-edge dimension 42a of the tooth head of the second tooth. Fig.13 and Fig.14 The different facets of the tooth surface are shown, where Fig.13 The surface area of ​​the central facet 43 (the facet intersecting the tooth axis 27) is greater than Fig.14 In addition, the facets next to the central facet 43 have a Fig.14 The corresponding facets in Fig.14 The central facet (and central axis 27) is positioned at a more oblique angle than the central facet.

[0050] In various embodiments, the asymmetry of the tooth surface may include: Figure 7 The symmetrical teeth are opposite, with respect to the curvature radius of the tooth surface on one side of the tooth axis 27, and the curvature radius of the tooth surface on the other side of the tooth axis is changed, such as Figure 8 or otherwise, increasing or decreasing the backlash 16 (the distance between the tooth and the rotor) on one side of the tooth axis relative to one side of the tooth axis. In some embodiments, the tooth surface may be asymmetrical because the tooth head 30 is narrower or wider on one side of the tooth axis than on the other side of the tooth axis. Fig. 9As shown, the first stator portion 13a can be paired with a second stator portion 13b having an asymmetry opposite to the asymmetry to cancel the asymmetry in the magnetic field of the coils / teeth of the first stator portion. Any suitable method, such as those discussed above, can be used to impart asymmetry to the shapes of the teeth / coils of the first and second stator portions, and the specific asymmetry of the first and second stator layers is selected and sized to at least partially cancel the asymmetry or distortion of each other's magnetic fields and at least partially reduce torque ripple and / or cogging torque.

[0051] In some embodiments of the laminated stator 13 described herein, the first stator portion 13a may be arranged in series with the second stator portion 13b, wherein the two stator portions are arranged end to end so that the center line of the first stator portion is coaxial with the second stator portion, and the teeth and winding openings of the first stator portion correspond to the teeth and winding openings of the second stator portion, respectively, to allow each coil to be made by winding a conductor around one tooth of the first stator portion and one tooth of the second stator portion.

[0052] In some embodiments, there may also be a third stator layer, such as a stator layer that lacks the asymmetry of the first and second layers, or a stator layer that has an asymmetry as described for the first and second layers. In various embodiments, the third stator layer may be located between the first and second stator layers, or may be located at one end or the other of the first and second stator layer assembly.

[0053] In some embodiments, asymmetric first and second stator layers (and optionally a third stator layer) may be used with a rotor that does not have the asymmetric features described herein.

[0054] In a third method of reducing torque fluctuations, asymmetric rotor layers and asymmetric stator layers can be combined with each other, for example, a rotor having an asymmetric layer and an opposite asymmetric layer, or a layer without the asymmetric characteristics described herein, is combined with a stator having an asymmetric layer and an opposite asymmetric layer (non-asymmetric layer), or a layer without the asymmetric characteristics described herein (non-asymmetric stator layer).

[0055] In some embodiments, an asymmetric rotor layer may be offset by an asymmetric stator layer adjacent to the asymmetric rotor layer or adjacent to a different rotor layer. In some embodiments, an asymmetric rotor layer may be offset by an asymmetric stator layer and an asymmetric rotor layer, wherein the asymmetric stator layer is adjacent to the asymmetric rotor layer or adjacent to an opposite asymmetric rotor layer. In some embodiments, an asymmetric stator layer may be offset by an asymmetric stator layer and an asymmetric rotor layer, wherein the asymmetric rotor layer is adjacent to the asymmetric rotor layer or adjacent to an opposite asymmetric stator layer.

[0056] As used herein, the words "approximately", "about", "substantially", "close to" and other similar words and phrases should be understood by those skilled in the art to allow for a certain amount of variation without substantially affecting the functioning of the device, example or embodiment. In those cases where further specification is required, the degree of variation should be understood to be 5% or less.

[0057] Having now described the invention in accordance with the requirements of the patent statutes, those skilled in the art will understand how to change and modify the invention to meet their specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention disclosed herein.

[0058] As required by law, the foregoing detailed description of exemplary and preferred embodiments is given for exemplary and public purposes. This description is neither exhaustive nor intended to limit the invention to the precise form described, but is only intended to enable other persons skilled in the art to understand how the invention can be adapted to a particular use or implementation. The possibility of modification and variation will be apparent to those skilled in the art. The description of the exemplary embodiments is not intended to be limiting, and may include tolerances, feature sizes, specific operating conditions, engineering specifications, etc., and may vary between implementations or as the state of the art changes, and no limitation should be implied thereby. The applicant has made this disclosure relative to the current state of the art, but progress is also contemplated, and future improvements may consider those progresses in light of the subsequent state of the art. The scope of the invention is defined by the written claims and applicable equivalents. Unless expressly stated, reference to a claimed element in the singular does not mean "there is and only one". In addition, no element, component, method or process step in this disclosure is intended to be dedicated to the public, regardless of whether the element, component or step is explicitly stated in the claim.

Claims

1. A motor rotor, include: A rotor comprising a first rotor portion, a second rotor portion and a series of magnets, The first rotor portion comprises: a series of magnet receptacles adjacent an outer edge of the first rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed about the first rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the first rotor portion; The first rotor portion comprises, for each magnet, a respective air hole or air barrier that is asymmetric with respect to a respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field for the respective magnet; The second rotor portion comprises: a series of magnet receptacles adjacent an outer edge of the second rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed about the second rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the second rotor portion; The second rotor portion comprises, for each magnet, a respective air hole or air barrier that is asymmetric about the respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field for the respective magnet; wherein the first rotor portion is arranged in series with the second rotor portion, and a magnet receiving portion of the first rotor portion corresponds to a magnet receiving portion of the second rotor portion; and wherein each of the magnets is located within a magnet receiving portion of the first rotor portion and a magnet receiving portion of the second rotor portion; wherein during operation, the asymmetry of the magnetic field of the second rotor part causes torque fluctuations which at least partially offset the fluctuations of the asymmetry of the magnetic field of the first rotor part, Wherein, the respective air holes or air barriers of the first rotor part are located only on one side of the respective d-axis, and the respective air holes or air barriers of the second rotor part are located only on the other side of the respective d-axis opposite to one side of the respective d-axis relative to the respective d-axis.

2. The electric motor rotor of claim 1, wherein the asymmetry of the magnetic field in the first rotor portion and the second rotor portion is caused only by the asymmetry in the air holes.

3. The motor rotor according to claim 1, in, The asymmetry of the magnetic field in the first rotor part and the second rotor part is caused only by the asymmetry in the gas barrier.

4. The electric motor rotor according to claim 1, further comprising a third rotor portion, The third rotor portion include: a series of magnet receptacles adjacent an outer edge of the third rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed about the third rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the first rotor portion; wherein the third rotor portion is aligned with the first rotor portion and the second rotor portion, and the magnet receiving portion of the third rotor portion corresponds to the magnet receiving portion of the first rotor portion and the second rotor portion; and Each of the magnets is located within a magnet receiving portion of the first rotor portion, the second rotor portion, and the third rotor portion.

5. The electric motor rotor of claim 4 , wherein the third rotor portion comprises, for each magnet, respective air holes or air barriers that are asymmetric with respect to the respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field of the respective magnet, and during operation, the asymmetry of the magnetic field of the third rotor portion causes torque fluctuations that at least partially offset the fluctuations of the asymmetry of the magnetic field of the first rotor portion and / or the second rotor portion.

6. A stator of an electric motor, include: a first stator portion, a second stator portion and a series of coils, The first stator part comprises: a series of winding openings, each winding opening configured to receive a wire to form one of a series of coils wound around teeth of the first stator portion; Each tooth of the first stator portion provides a first stator magnetic field; The second stator portion comprises: a series of winding openings, each winding opening configured to receive a wire to form one of a series of coils wound around teeth of the second stator portion; Each tooth of the second stator portion provides a second stator magnetic field; wherein the first stator portion is arranged in series with the second stator portion, the teeth of the first stator portion correspond to the teeth of the second stator portion, and the coil for each tooth is made by winding a conductor around the tooth of the first stator portion and the corresponding tooth of the second stator portion, and During operation, the first stator magnetic field induces a first torque fluctuation, which at least partially cancels a second torque fluctuation caused by the second stator magnetic field, Wherein each tooth of the first stator portion has an asymmetric shape relative to a respective tooth axis of each tooth of the first stator portion, and each tooth of the second stator portion has an asymmetric shape relative to a respective tooth axis of each tooth of the second stator portion.

7. An electric motor stator according to claim 6, wherein the teeth of the first stator include a first tooth head, the first tooth head has a first tooth head shape, the teeth of the second stator part include a second tooth head, the second tooth head has a second tooth head shape, the first tooth head and the second tooth head are different from each other, and the difference between the first torque fluctuation and the second torque fluctuation is related to the difference between the first tooth head shape and the second tooth head shape. 8 . The motor stator of claim 7 , wherein the first tooth head shape and the second tooth head shape have different side-to-side widths.

9. The motor stator of claim 7, wherein the first tooth head has a face including one or more facets, and the second tooth head has a face including one or more facets corresponding to the one or more facets of the first tooth head, and the first tooth head shape and the second tooth head shape are different in the surface area of ​​the facets of the first tooth head and the surface area of ​​the corresponding facets of the second tooth head.

10. The electric motor stator according to claim 6, further comprising a third stator portion; The third stator part include: a series of winding openings, each winding opening configured to receive a wire to form one of a series of coils wound around teeth of the third stator portion; Each tooth of the third stator provides a third stator magnetic field; The third stator portion is arranged in series with the first stator portion and the second stator portion, the teeth of the third stator portion correspond to the teeth of the first stator portion and the second stator portion, and the coil of each tooth is made by winding a conductor around the tooth of the first stator portion, the corresponding tooth of the second stator portion, and the corresponding tooth of the third stator portion. 11 . The motor stator according to claim 10 , wherein the third stator magnetic field causes torque fluctuations, and the torque fluctuations at least partially offset the torque fluctuations caused by the first stator magnetic field and / or the second stator magnetic field.

12. An electric motor, include: a rotor comprising a first rotor portion, a second rotor portion, and a series of magnets; and The motor stator comprises a first stator part, a second stator part and a series of coils, in, The first rotor portion comprises: a series of magnet receptacles adjacent an outer edge of the first rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed about the first rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the first rotor portion; the first rotor portion comprising, for each magnet, a respective air hole or air barrier that is asymmetric about a respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field for the respective magnet; The second rotor portion comprises: a series of magnet receptacles adjacent an outer edge of the second rotor portion and configured to receive respective magnets to magnetically interact with a series of coils located in the stator and distributed about the second rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the second rotor portion; the second rotor portion comprising, for each magnet, a respective air hole or air barrier that is asymmetric about a respective d-axis; wherein each air hole or air barrier results in an asymmetric magnetic field for the respective magnet; wherein the first rotor portion is arranged in series with the second rotor portion, and a magnet receiving portion of the first rotor portion corresponds to a magnet receiving portion of the second rotor portion; and wherein each of the magnets is located within a magnet receiving portion of the first rotor portion and a magnet receiving portion of the second rotor portion; The first stator part comprises: a series of winding openings, each winding opening configured to receive a wire to form one of a series of coils wound around teeth of the first stator portion; Each tooth of the first stator portion provides a first stator magnetic field; The second stator portion comprises: a series of winding openings, each winding opening configured to receive a wire to form one of a series of coils wound around teeth of the second stator portion; Each tooth of the second stator portion provides a second stator magnetic field; wherein the first stator portion is arranged in series with the second stator portion, the teeth of the first stator portion correspond to the teeth of the second stator portion, and the coil of each tooth is made by winding a conductor around the tooth of the first stator portion and the corresponding tooth of the second stator portion; and During operation, the first stator magnetic field induces a first torque fluctuation that at least partially cancels a second torque fluctuation induced by the second stator magnetic field, The respective air holes or air barriers of the first rotor part are located only on one side of the respective d-axis, and the respective air holes or air barriers of the second rotor part are located only on the other side of the respective d-axis opposite to one side of the respective d-axis relative to the respective d-axis.

13. An electric motor according to claim 12, wherein the teeth of the first stator include a first tooth head, the first tooth head has a first tooth head shape, the teeth of the second stator part include a second tooth head, the second tooth head has a second tooth head shape, the first tooth head and the second tooth head are different from each other, and the difference between the first torque fluctuation and the second torque fluctuation is related to the difference between the first tooth head shape and the second tooth head shape.

14. The electric motor of claim 13, wherein the first tooth head shape and the second tooth head shape have different side-to-side widths.

15. An electric motor according to claim 13, wherein the first tooth head has a face including one or more facets, and the second tooth head has a face including one or more facets corresponding to the one or more facets of the first tooth head, and the first tooth head shape and the second tooth head shape are different in the surface area of ​​the facets of the first tooth head and the surface area of ​​the corresponding facets of the second tooth head.

16. The electric motor of claim 12, wherein the asymmetry of the magnetic field in the first rotor portion and the second rotor portion is caused only by the asymmetry in the air holes.

17. The electric motor of claim 12, wherein the asymmetry of the magnetic field in the first rotor portion and the second rotor portion is caused only by the asymmetry in the air barrier.

18. The electric motor of claim 12, further comprising a third rotor portion, The third rotor portion include: a series of magnet receptacles adjacent an outer edge of the third rotor portion and configured to receive respective magnets to magnetically interact with a series of coils disposed in the stator and distributed about the third rotor portion to effect relative rotation of the rotor and the stator when the coils are energized during operation; Each of the magnets has a respective d-axis extending through the magnet and an outer edge of the first rotor portion; wherein the third rotor portion is aligned with the first rotor portion and the second rotor portion, and a magnet receiving portion of the third rotor portion corresponds to a magnet receiving portion of the first rotor portion and the second rotor portion; and Each of the magnets is located within a magnet receiving portion of the first rotor portion, the second rotor portion, and the third rotor portion.

19. An electric motor according to claim 18, wherein the third rotor portion comprises, for each magnet, respective air holes or air barriers which are asymmetric relative to respective d-axis lines; wherein each air hole or air barrier results in an asymmetric magnetic field for the respective magnet, and during operation, the asymmetry of the magnetic field of the third rotor portion causes torque fluctuations which at least partially offset the asymmetric fluctuations of the magnetic field of the first rotor portion and / or the second rotor portion.

Images