Method for generating constant torque of motor, rotor core, rotor and motor

Abstract

The present invention provides a method for generating a constant torque in a motor, a rotor core, a rotor and a motor. The method for generating a constant torque in a motor includes generating an uneven magnetomotive force between the stator and the rotor during the operation of the motor, and the uneven magnetomotive force can at least partially cancel the torque pulsation magnetomotive force between the stator and the rotor. The rotor core of the present invention can be provided with permanent magnets, and through the uneven distribution of the permanent magnets and the cooperation with the magnetic steel, an uneven magnetomotive force is generated, so that the output of the motor itself is an uneven magnetic field, generating an uneven magnetomotive force, which cancels out the pulsation magnetomotive force.

Description

Technical Field

[0001] The present invention relates to the technical field related to motors, and in particular to a method for generating a constant torque for a motor, a rotor core, a rotor, and a motor. Background Art

[0002] Generally, the torque of a motor is proportional to the magnetic flux density generated at the gap between the stator and the rotor. To generate a constant torque, we hope that the magnetomotive force uniformly distributed in the air gap between the stator and the rotor is generally sinusoidally distributed. However, in practice, due to many irregular structures between the stator and the rotor, which is not a smooth transition, the magnetomotive force distribution is not a sine wave. Therefore, there are many harmonic components in the actually generated magnetomotive force, resulting in magnetic bias. The torque ripple generated by the magnetic bias of such a magnetomotive force distribution increases the torque ripple and causes relatively large noise and vibration. To make the motor generate a constant torque, we hope that the magnetomotive force distribution in the air gap magnetic field is close to a sine wave to reduce the magnetic bias phenomenon caused by the magnetomotive force distribution. Summary of the Invention

[0003] In view of this, the present invention provides a method for generating a constant torque for a motor, a rotor core, a rotor, and a motor, which is at least used to solve the technical problem of large torque ripple of the motor in the prior art. Specifically:

[0004] The present invention provides a method for generating a constant torque for a motor. During the operation of the motor, an uneven magnetomotive force is generated between the stator and the rotor, and the uneven magnetomotive force can at least partially cancel the torque ripple magnetomotive force between the stator and the rotor.

[0005] Further optionally, a permanent magnet is arranged on the rotor core of the rotor, and the permanent magnet and the magnetic steel on the rotor core act together to generate an uneven magnetomotive force.

[0006] In a second aspect, the present invention provides a rotor core,

[0007] Magnetic steel grooves for installing magnetic steel are arranged on the rotor core, and the part between each magnetic steel groove and the outer circle of the rotor core forms the yoke part of the rotor core. A plurality of the yoke parts are distributed along the circumferential direction of the rotor core;

[0008] At least one of the yoke parts is provided with a permanent magnet groove for installing a permanent magnet;

[0009] The permanent magnet in the permanent magnet groove and the magnetic steel in the magnetic steel groove act to generate an uneven magnetomotive force.

[0010] Further optionally, the permanent magnet grooves are unevenly distributed along the circumferential direction of the rotor core.

[0011] Further optionally, the permanent magnet slot penetrates axially through the rotor core to form a through hole, or the permanent magnet slot is configured as a blind hole formed on one end face of the rotor core.

[0012] Further optionally, the permanent magnet slots are arranged in segments along the axial direction of the rotor core, and there are intervals between multiple segments.

[0013] Further optionally, the permanent magnet slots are divided into two or three segments.

[0014] Further optionally, one permanent magnet slot is provided on the yoke, and the permanent magnet slot is provided on a part of the yoke; or,

[0015] Permanent magnet slots are provided on all the yokes, multiple permanent magnet slots are provided on each yoke, and the number of permanent magnet slots on at least one yoke is different from that on other yokes, so that the permanent magnet slots are unevenly distributed in the circumferential direction of the rotor core.

[0016] Further optionally, the central angle corresponding to the area on the yoke for setting the permanent magnet slot is α, where α = 0.8×360 / P, and P is the number of rotor poles.

[0017] Further optionally, a magnetic flux rectifying slot is provided on the yoke.

[0018] Further optionally, the minimum distances between the permanent magnet slot and the outer circle of the rotor core, the magnet slot, and the magnetic flux rectifying slot are all not less than 2 mm.

[0019] In a third aspect, the present invention provides a rotor, including the above-mentioned rotor core;

[0020] A magnet steel, arranged in the magnet steel slot;

[0021] A permanent magnet, arranged in the permanent magnet slot.

[0022] Further optionally, the permanent magnet is composed of neodymium iron boron, ferrite, aluminum nickel cobalt or samarium cobalt.

[0023] In a fourth aspect, the present invention provides an electric motor, including the above-mentioned rotor.

[0024] By arranging permanent magnet slots on the rotor core and distributing the permanent magnet slots unevenly along the circumferential direction of the rotor core, permanent magnets can be arranged unevenly along the circumferential direction of the rotor core. Thereby, the motor can generate an uneven magnetomotive force, and through the uneven distribution of the shape and quantity of the permanent magnets, the generated uneven magnetomotive force can cancel out the pulsating magnetomotive force of the motor. Thereby, the torque ripple caused by the uneven air gap is suppressed, the content of the effective fundamental wave in the air gap magnetic field is increased, other order harmonics are reduced, the reliability of the motor is improved, the motor efficiency is increased, and the problems of motor vibration and noise are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By referring to the drawings and describing its exemplary embodiments in detail, the above and other objects, features and advantages of the present disclosure will become more apparent. The drawings described below are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 Schematic diagram of the rotor core structure according to an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the end face of the rotor core according to an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the end face of the rotor core according to an embodiment of the present invention (permanent magnet slots are arranged in multiple yokes);

[0029] Figure 4 Schematic diagram of the end face of the rotor core according to an embodiment of the present invention (including permanent magnet slots of different shapes);

[0030] Figure 5 Schematic diagram of the end face of the rotor core according to an embodiment of the present invention (including arc-shaped permanent magnet slots);

[0031] Figure 6 Schematic diagram of the cross-section of the rotor core according to an embodiment of the present invention;

[0032] Figure 7 Schematic diagram of the cross-section of the rotor core according to an embodiment of the present invention (the permanent magnet slot includes two sections);

[0033] Figure 8 Schematic diagram of the area where the permanent magnet slot is arranged according to an embodiment of the present invention;

[0034] Figure 9 Schematic diagram of the end face of the rotor according to an embodiment of the present invention;

[0035] Figure 10 Schematic diagram of the cross-section of the rotor according to an embodiment of the present invention;

[0036] Figure 11Schematic diagram of the rotor cross-section according to an embodiment of the present invention (the permanent magnet includes two segments).

[0037] In the figure:

[0038] 10. Rotor core; 11. Magnet slot; 12. Yoke; 13. Permanent magnet slot; 14. Magnetic flux conditioning slot; 15. Central hole; 16. Rivet hole; 20. Magnet; 30. Permanent magnet. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two, but does not exclude the case of including at least one.

[0041] It should be understood that the term "and / or" used herein is only a description of the associated relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0042] It should also be noted that the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a commodity or system including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such commodity or system. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the commodity or system including the said element.

[0043] The present invention sets permanent magnets on the yoke of the rotor. The permanent magnets and the magnetic steel on the rotor act together to make the motor generate an uneven magnetomotive force. By the uneven distribution of the shape and quantity of the permanent magnets, the generated uneven magnetomotive force cancels out the pulsating magnetomotive force of the motor. Thereby, the increase in current is inhibited, the load variation is inhibited, the magnetic bias phenomenon is cancelled out, the distribution of the magnetomotive force in the air-gap magnetic field is closer to the sine-wave distribution, the pulsating magnetomotive force caused by magnetic bias is cancelled out, the torque pulsation caused by the uneven air gap is inhibited, the effective fundamental wave content in the air-gap magnetic field is increased, other order harmonics are reduced, the reliability of the motor is improved, the motor efficiency is increased, and the problems of motor vibration and noise are improved. The following introduces the present invention in detail in combination with specific embodiments.

[0044] The present invention provides a method for making a motor generate a constant torque. During the operation of the motor, an uneven magnetomotive force is generated between the stator and the rotor, and the uneven magnetomotive force can at least partially cancel out the torque pulsation magnetomotive force between the stator and the rotor. By the mutual cancellation of the uneven magnetomotive force and the pulsating magnetomotive force, the increase in current is inhibited, the load variation is inhibited, the magnetic bias phenomenon is cancelled out, and the distribution of the magnetomotive force in the air-gap magnetic field is closer to the sine-wave distribution.

[0045] Preferably, permanent magnets are set on the rotor core of the rotor. The permanent magnets and the magnetic steel on the rotor core act together to generate an uneven magnetomotive force. It is easy to think that the stator or other structures can also be improved to generate an uneven magnetomotive force between the stator and the rotor, which can also play the role of cancelling out the pulsating magnetomotive force.

[0046] As Figure 1 、 Figure 2 shown, the present invention provides a rotor core 10,

[0047] Magnetic steel grooves 11 for installing magnetic steel are provided on the rotor core 10. The part between each magnetic steel groove 11 and the outer circle of the rotor core 10 forms the yoke 12 of the rotor core. A plurality of yokes 12 are distributed along the circumferential direction of the rotor core 10;

[0048] At least one yoke 12 is provided with permanent magnet grooves 13 along the axial direction of the rotor core 10. The permanent magnet grooves 13 are arranged parallel to the magnetic steel grooves 11 and are used for installing permanent magnets;

[0049] The permanent magnet grooves 13 are distributed in an uneven state along the circumferential direction of the rotor core 10.

[0050] The rotor core 10 is constructed as a columnar structure. A central hole 15 for installing a drive shaft is provided in the central part of the rotor core 10. The axis of the central hole 15 coincides with the axis of the rotor core 10. A plurality of rivet holes 16 for connecting rivets are also provided on the end face of the rotor core 10. The plurality of rivet holes 16 are evenly distributed around the central hole 15.

[0051] A plurality of magnet slots 11 are provided and are evenly distributed around the central hole 15. The magnet slots 11 are configured as straight slots or V-shaped slots, etc., and are arranged at a position close to the edge of the rotor core 10. In this embodiment, the magnet slots 11 are configured as straight slots and are distributed in a regular hexagon. The region enclosed by the magnet slots 11 and the edge of the rotor core 10 forms the yoke portion 12 of the rotor core 10, and each magnet slot 11 correspondingly forms a yoke portion 12.

[0052] As Figure 2 、 Figure 3 shown, in one embodiment, permanent magnet slots 13 are provided on a part of the yoke portion 12, and one permanent magnet slot 13 is provided on one yoke portion 12. Specifically, the number of magnet slots 11 is N (i.e., the number of yoke portions 12 is N), and the number of yoke portions 12 provided with permanent magnet slots 13 is less than or equal to N - 1 to ensure that the permanent magnet slots 13 form an uneven distribution state in the circumferential direction of the rotor core 10. For example, if 6 magnet slots 11 are provided, permanent magnet slots 13 can be provided on 1 of the yoke portions 12, or on 2 of the yoke portions 12, and at most on 5 of the yoke portions 12.

[0053] Alternatively, in other embodiments, one or more permanent magnet slots 13 can also be provided on one yoke portion 12, and in this embodiment, permanent magnet slots 13 can be provided on each yoke portion 12, and the number of permanent magnet slots 13 on at least one yoke portion 12 is different from the number of permanent magnet slots 13 on other yoke portions 12 to make the permanent magnet slots 13 form an uneven distribution state in the circumferential direction of the rotor core 10.

[0054] Preferably, as Figure 6 shown, the permanent magnet slot 13 axially penetrates the rotor core 10 to form a through hole, which is arranged parallel to the magnet hole. Alternatively, the permanent magnet slot 13 is configured as a blind hole formed on one end face of the rotor core 10, that is, the permanent magnet slot 13 extends along a direction parallel to the axis of the rotor core 10 on one end face of the rotor core 10, and the extension length is less than the length of the rotor core 10.

[0055] Alternatively, the permanent magnet slot 13 is axially segmented on the rotor core 10, and there is a gap between multiple segments, preferably two or three segments are provided. For example, as Figure 7 shown, it can be divided into two segments, which respectively extend from both ends of the rotor core 10 towards the inside and are not connected to each other.

[0056] As Figure 4 、 Figure 5 shown, the end face shape of the permanent magnet slot 13 is rectangular, trapezoidal, arc-shaped, etc., and no specific limitation is imposed on its shape, and it can be set according to needs.

[0057] The permanent magnet slot 13 is provided inside the yoke portion 12 and cannot exceed the outer edge of the yoke portion 12. Preferably, as Figure 8As shown, the central angle corresponding to the area on the yoke 12 for arranging the permanent magnet slots 13 is α, where α = 0.8×360 / P, and P is the number of rotor poles, that is, the number of poles of the motor. That is, on each yoke 12, the permanent magnet slots 13 can only be arranged within the range of the corresponding central angle α. The permanent magnet slots 13 can be arranged at the middle position of the yoke 12 or at a position close to the edge of the yoke 12.

[0058] Preferably, the distance between the permanent magnet slots 13 and the edge of the rotor core 10 and the magnet slots 11 should not be too small, and at least a distance of more than 2 mm should be maintained to avoid too high local magnetic density and resulting local heating.

[0059] Furthermore, magnetic flux rectifying slots 14 are also arranged on the yokes 12, and magnetic flux rectifying slots 14 are arranged on each yoke 12. When both magnetic flux rectifying slots 14 and permanent magnet slots 13 are arranged on the yoke 12, the permanent magnet slots 13 and the magnetic flux rectifying slots 14 also need to maintain a distance of at least 2 mm to avoid interference between the permanent magnet slots 13 and the magnetic flux rectifying slots 14 and also avoid excessive local heat generation caused by too high local magnetic density.

[0060] In the present invention, by arranging the permanent magnet slots 13 on the yoke 12 and making the permanent magnet slots 13 unevenly distributed along the circumferential direction of the rotor core 10, an uneven excitation can be generated by arranging permanent magnets on the yoke 12 of the rotor core 10 to cancel the harmonic pulsation in the air-gap magnetic field. Thereby, the torque pulsation caused by uneven air-gap is suppressed, the content of the effective fundamental wave in the air-gap magnetic field is increased, other order harmonics are reduced, the reliability of the motor is improved, the motor efficiency is increased, and the problems of motor vibration and noise are improved.

[0061] The present invention also provides a rotor, including the above-mentioned rotor core 10, as Figure 9 shown, further including a magnet 20 arranged in the magnet slot 11. The magnet 20 is embedded in the magnet slot 11, and the shape of the magnet 20 is the same as that of the magnet slot 11. The two ends of the magnet 20 are flush with the two end faces of the rotor core 10.

[0062] The rotor further includes a permanent magnet 30 arranged in the permanent magnet slot 13. The shape of the permanent magnet 30 is the same as that of the permanent magnet slot 13. The permanent magnet 30 is embedded in the magnet slot 11 and is flush with the end face where the magnet slot 11 is located. Preferably, the material of the permanent magnet 30 is neodymium iron boron, ferrite, alnico or samarium cobalt, etc. As Figure 10 shown, when the permanent magnet slot 13 penetrates axially along the rotor core 10, the length of the permanent magnet 30 is the same as that of the permanent magnet slot 13, that is, the length of the permanent magnet 30 is the same as that of the rotor core 10; or, as Figure 11 shown, when the permanent magnet slot 13 is divided into two sections, the permanent magnet 30 is adapted to the shape of the permanent magnet slot 13 and is arranged in two sections.

[0063] The present invention also provides a motor, comprising a stator and the above-mentioned rotor, wherein the rotor is rotatably engaged with the stator, and a central hole 15 of the rotor core 10 is connected to a drive shaft, and the rotation of the rotor drives the drive shaft to rotate.

[0064] In the present invention, by arranging permanent magnets on the yoke of the rotor, the permanent magnets and the magnetic steel on the rotor act together to make the motor generate an uneven magnetomotive force. Through the uneven distribution of the shape and quantity of the permanent magnets, the generated uneven magnetomotive force cancels out the pulsating magnetomotive force of the motor, suppresses the increase of current, and suppresses the load variation, cancels the magnetic bias phenomenon, making the distribution of the magnetomotive force in the air-gap magnetic field closer to the sine-wave distribution, canceling the pulsating magnetomotive force generated by magnetic bias, thereby suppressing the torque pulsation generated by the uneven air gap, increasing the effective fundamental wave content in the air-gap magnetic field, reducing other order harmonics, improving the reliability of the motor, increasing the motor efficiency, and improving the motor vibration and noise problems.

[0065] The exemplary embodiments of the present disclosure have been specifically illustrated and described above. It should be understood that the present disclosure is not limited to the detailed structures, arrangements or implementation methods described herein; on the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for generating a constant torque in a motor, characterized in that: During the operation of the motor, an uneven magnetomotive force is generated between the stator and the rotor by installing permanent magnets on at least one yoke of the rotor core, and the uneven magnetomotive force can at least partially cancel the torque pulsation magnetomotive force between the stator and the rotor. Wherein, a magnet slot for installing a magnet steel is arranged on the rotor core, and a part between each magnet slot and the outer circumference of the rotor core constitutes the yoke of the rotor core; a plurality of the magnet slots are evenly distributed around the central axis of the rotor core, and a plurality of the permanent magnets are unevenly distributed around the central axis of the rotor core.

2. The method according to claim 1, wherein: Permanent magnets are arranged on the rotor core of the rotor, and the permanent magnets and the magnet steels on the rotor core act together to generate an uneven magnetomotive force.

3. A rotor core, characterized in that: A magnet slot for installing a magnet steel is arranged on the rotor core, and a part between each magnet slot and the outer circumference of the rotor core constitutes the yoke of the rotor core, and a plurality of the yokes are distributed along the circumferential direction of the rotor core; At least one of the yokes has a permanent magnet slot for installing a permanent magnet; The permanent magnet in the permanent magnet slot and the magnet steel in the magnet slot act to generate an uneven magnetomotive force; A plurality of the magnet slots are evenly distributed around the central axis of the rotor core, and a plurality of the permanent magnets are unevenly distributed around the central axis of the rotor core.

4. The rotor core according to claim 3, wherein: The permanent magnet slot penetrates axially along the rotor core to form a through hole, or the permanent magnet slot is configured as a blind hole formed on one end face of the rotor core.

5. The rotor core according to claim 4, wherein: The permanent magnet slots are arranged in sections axially along the rotor core, and there is an interval between multiple sections.

6. The rotor core according to claim 4, characterized in that: The permanent magnet slot is divided into two or three sections.

7. The rotor core according to claim 4, wherein: One permanent magnet slot is arranged on the yoke, and the permanent magnet slot is arranged on a part of the yoke; or, Permanent magnet slots are arranged on all the yokes, a plurality of permanent magnet slots are arranged on each yoke, and the number of permanent magnet slots on at least one yoke is different from the number of permanent magnet slots on other yokes, so that the permanent magnet slots are unevenly distributed in the circumferential direction of the rotor core.

8. The rotor core according to any one of claims 3-7, characterized in that: The central angle corresponding to the area for arranging the permanent magnet slot on the yoke is α, where α = 0.8×360 / P, and P is the number of rotor poles.

9. The rotor core according to any one of claims 3-7, characterized in that: A magnetic flux rectifying slot is arranged on the yoke.

10. The rotor core according to claim 9, characterized in that: The minimum distances between the permanent magnet slot and the outer circumference of the rotor core, the magnet slot, and the magnetic flux rectifying slot are all not less than 2 mm.

11. A rotor, characterized in that: Comprising the rotor core according to any one of claims 3-10; Magnet steels, arranged in the magnet slots; Permanent magnets, arranged in the permanent magnet slots.

12. The rotor according to claim 11, characterized in that: The permanent magnet is composed of neodymium iron boron, ferrite, alnico or samarium cobalt.

13. A motor, characterized in that: Comprising the rotor according to claim 11 or 12.

Images