A magnetic field enhanced parallel magnetic circuit variable flux memory motor

Abstract

This invention discloses a magnetic field-enhanced parallel magnetic circuit variable flux memory motor, relating to the field of motor technology. The invention includes: a stator, comprising a stator core on which an armature winding is mounted; a hybrid permanent magnet rotor rotatably connected inside the stator; the hybrid permanent magnet rotor includes a rotor core on which multiple first permanent magnets are mounted, circumferentially distributed at the outer edge of the rotor core; second permanent magnets are mounted at both ends of each of the first permanent magnets, and the coercivity of the first permanent magnets is less than that of the second permanent magnets; multiple sector-shaped magnetic barriers are formed on the rotor core. This invention can significantly improve the load demagnetization resistance of low-coercivity permanent magnets, solving the problem of unstable operating point in parallel magnetic circuit variable flux memory motors, while maintaining the advantage of a wide magnetic adjustment range.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a magnetic field-enhanced parallel magnetic circuit variable flux memory motor. Background Technology

[0002] Because rare-earth permanent magnets (such as neodymium iron boron) have a high magnetic energy product, permanent magnet synchronous motors using rare-earth permanent magnets exhibit significant advantages such as high torque density, high power density, high efficiency, and high reliability. Furthermore, they offer diverse structural designs and are widely used in various sectors of the national economy. Hybrid permanent magnet memory motors, employing both high-coercivity constant flux permanent magnets and low-coercivity variable flux permanent magnets, inherit the advantages of high torque density and high power density of permanent magnet motors while also possessing the advantage of easily adjustable magnetic fields. Effective adjustment of the air gap magnetic field can be achieved simply by applying instantaneous charge / demagnetize current pulses. Therefore, hybrid permanent magnet memory motors have great application potential in applications requiring a wide speed range.

[0003] However, for traditional parallel magnetic circuit variable flux memory motors, the coercivity of AlNiCo permanent magnets is not high enough, and they are easily demagnetized by NdFeB permanent magnets under no-load conditions. In addition, under load conditions, AlNiCo permanent magnets are easily affected by the armature reaction magnetic field and the reverse demagnetization of NdFeB permanent magnets, resulting in unstable permanent magnet operating point, weak anti-load demagnetization ability, and low torque density. To address this, we propose a magnetic field enhanced parallel magnetic circuit variable flux memory motor. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetic field-enhanced parallel magnetic circuit variable flux memory motor, which can solve the problems of low coercivity permanent magnets being demagnetized by high coercivity permanent magnets and the operating point decreasing after being demagnetized by load current in current parallel magnetic circuit variable flux memory motors, resulting in weak load demagnetization resistance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a magnetic field-enhanced parallel magnetic circuit variable flux memory motor, comprising:

[0006] The stator includes a stator core on which an armature winding is mounted;

[0007] A hybrid permanent magnet rotor, which is rotatably connected inside the stator;

[0008] The hybrid permanent magnet rotor includes a rotor core, on which a plurality of first permanent magnets are mounted, and the plurality of first permanent magnets are evenly distributed circumferentially at the outer edge of the rotor core.

[0009] A second permanent magnet is installed at both ends of the first permanent magnet, and the coercivity of the first permanent magnet is less than that of the second permanent magnet.

[0010] The rotor core is provided with multiple sector-shaped magnetic barriers, and the multiple sector-shaped magnetic barriers are evenly distributed on the rotor core in the circumferential direction.

[0011] The opening of the sector-shaped magnetic barrier faces the outer edge of the rotor core. Each sector-shaped magnetic barrier is located between two adjacent first permanent magnets, and the axis of symmetry of the sector-shaped magnetic barrier coincides with the axis of symmetry of the two adjacent first permanent magnets.

[0012] Furthermore, the stator and the hybrid permanent magnet rotor are coaxially arranged, and an air gap is uniformly provided between the stator and the hybrid permanent magnet rotor.

[0013] Furthermore, a rotating shaft is installed at the center of the hybrid permanent magnet rotor.

[0014] Furthermore, the first permanent magnet is a low coercivity permanent magnet, and the cross-section of the first permanent magnet is arranged in a straight line.

[0015] Furthermore, the first permanent magnet is bidirectionally magnetized, with the magnetization direction parallel to the length direction of its shorter side, and the magnetization directions between adjacent first permanent magnets always remain opposite.

[0016] Furthermore, the second permanent magnet is a high coercivity permanent magnet, and the second permanent magnet is unidirectionally magnetized. Its magnetization direction is parallel to the magnetization direction of the first permanent magnet under the same magnetic pole, and the cross-section of the second permanent magnet is arranged in a straight line.

[0017] Furthermore, the magnetization directions of the two second permanent magnets under the same magnetic pole are the same, and the magnetization directions of the two second permanent magnets under adjacent magnetic poles always remain opposite.

[0018] Furthermore, the first permanent magnet and the second permanent magnet form a parallel magnetic circuit. When the magnetization directions of the first permanent magnet and the second permanent magnet are the same in the same magnetic pole, the motor is in a magnetizing state; otherwise, the motor is in a demagnetizing state.

[0019] Furthermore, the number of the first permanent magnet and the sector-shaped magnetic barrier are the same and both are even numbers, and the number of the second permanent magnet is twice the number of the first permanent magnet.

[0020] Furthermore, the first permanent magnet is an AlNiCo permanent magnet, and the second permanent magnet is a NdFeB permanent magnet.

[0021] This invention has at least the following beneficial effects:

[0022] 1) The present invention reduces the quadrature axis inductance by using a sector-shaped magnetic barrier. The motor exhibits anti-salient pole characteristics where the direct axis inductance is greater than the quadrature axis inductance. When under load, the armature current has a magnetizing effect on the low coercivity permanent magnet, thus improving the load demagnetization capability of the first permanent magnet.

[0023] 2) The first and second permanent magnets placed circumferentially in this invention are connected in parallel. When they are in the magnetization state, their magnetization directions are the same and the air gap magnetic flux density is high. When the first and second permanent magnets are in the demagnetization state, their magnetization directions are opposite and the magnetic lines of force form a loop inside the rotor, reducing the air gap magnetic flux density. Therefore, the air gap magnetic flux density can be flexibly adjusted by changing the magnetization state of the low coercivity permanent magnet.

[0024] 3) By placing a first permanent magnet with lower coercivity at the outer edge of the rotor, with its radial axis of symmetry located on the direct axis, and the magnetic bridge between the second permanent magnet with higher coercivity and the sector magnetic barrier being very narrow, the present invention can effectively reduce the amplitude of the direct axis magnetization current and improve the magnetization and demagnetization efficiency.

[0025] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention;

[0027] Figure 2 This is a front view schematic diagram of the stator structure of the present invention;

[0028] Figure 3 This is a front view schematic diagram of the rotor structure of the present invention;

[0029] Figure 4 This is a diagram showing the distribution of magnetic field lines under the magnetized state of the present invention;

[0030] Figure 5 This is a diagram showing the distribution of magnetic field lines under the demagnetized state of the present invention;

[0031] Figure 6 This is a diagram showing the change in the operating point of the first permanent magnet before and after loading.

[0032] Figure label:

[0033] 1. Stator; 11. Stator core; 12. Armature winding; 13. Stator yoke; 14. Stator teeth; 15. Stator slot; 2. Hybrid permanent magnet rotor; 21. Rotor core; 22. First permanent magnet; 23. Second permanent magnet; 24. Sector-shaped magnetic barrier; 3. Shaft. Detailed Implementation

[0034] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0035] Please see Figure 1-3 This invention provides a technical solution: a magnetic field-enhanced parallel magnetic circuit variable flux memory motor, comprising:

[0036] Stator 1 includes a stator core 11, a stator yoke 13 is provided on the stator core 11, and a plurality of stator teeth 14 are provided on the inner circumference of the stator core 11. A stator slot 15 is formed between two adjacent stator teeth 14, and the armature winding 12 is wound on the stator teeth 14.

[0037] The hybrid permanent magnet rotor 2 is rotatably connected inside the stator 1. A rotating shaft 3 is installed at the center of the hybrid permanent magnet rotor 2. The stator 1 and the hybrid permanent magnet rotor 2 are coaxially arranged.

[0038] The hybrid permanent magnet rotor 2 includes a rotor core 21, on which multiple first permanent magnets 22 with a cross-section arranged in a "I" shape are mounted. The multiple first permanent magnets 22 are evenly distributed around the outer edge of the rotor core 21. The first permanent magnets 22 are bidirectionally magnetized, with the magnetization direction parallel to the length direction of their shorter side. Before being magnetized by an instantaneous pulse current, the magnetization direction of the first permanent magnets 22 is opposite to the magnetization direction of the second permanent magnets 23 distributed around the end. After being magnetized by an instantaneous pulse current, the magnetization direction of the first permanent magnets 22 is the same as the magnetization direction of the second permanent magnets 23 distributed around the end. The radial axis of symmetry of the first permanent magnets 22 coincides with the center line of the rotor pole, and the magnetization directions of adjacent first permanent magnets 22 are opposite.

[0039] The first permanent magnet 22 has a second permanent magnet 23 installed at both ends. The coercivity of the first permanent magnet 22 is less than that of the second permanent magnet 23. The second permanent magnet 23 is unidirectionally magnetized, and its magnetization direction is parallel to that of the first permanent magnet 22 under the same magnetic pole. Specifically, it is the same as the magnetization direction of the first permanent magnet 22 under the same magnetic pole in the magnetization state, and opposite in the demagnetization state. The cross-section of the second permanent magnet 23 is arranged in a straight line, and the magnetization directions of the two second permanent magnets 23 under the same magnetic pole are the same. The magnetization directions of the two second permanent magnets 23 under adjacent magnetic poles are always opposite.

[0040] The first permanent magnet 22 and the second permanent magnet 23 form a parallel magnetic circuit. When the magnetization directions of the first permanent magnet 22 and the second permanent magnet 23 are the same in the same magnetic pole, the motor is in a magnetizing state; otherwise, the motor is in a demagnetizing state.

[0041] Multiple sector-shaped magnetic barriers 24 are provided on the rotor core 21, and the multiple sector-shaped magnetic barriers 24 are evenly distributed around the rotor core 21. The opening of the sector-shaped magnetic barriers 24 faces the outer edge of the rotor core 21. Each sector-shaped magnetic barrier 24 is located between two adjacent first permanent magnets 22, and the axis of symmetry of the sector-shaped magnetic barrier 24 coincides with the axis of symmetry of the two adjacent first permanent magnets 22. The radius of the sector-shaped magnetic barrier 24 is larger than the thickness of the first permanent magnet 22. The larger radius is to reduce the quadrature axis inductance, so that the motor exhibits the anti-salient pole characteristic that the direct axis inductance is greater than the quadrature axis inductance. When under load, the armature current has a magnetizing effect on the first permanent magnet 22, thereby improving the anti-demagnetization capability of the first permanent magnet 22 under load.

[0042] It should be noted that both the stator core 11 and the rotor core 21 are made of silicon steel sheets with a thickness of 0.35mm, and the stacking coefficient is 0.95. There is a uniform air gap between the inner wall of the stator 1 and the outer wall of the hybrid permanent magnet rotor 2. The thickness of the air gap is related to the power rating of the motor, the permanent magnet material selected, and the processing and assembly process of the stator 1 and the hybrid permanent magnet rotor 2.

[0043] Furthermore, a gap is provided between the fan-shaped magnetic barrier 24 and the second permanent magnet 23. This gap can reduce the leakage magnetic flux at both ends of the second permanent magnet 23, improve the magnetization or demagnetization efficiency of the instantaneous pulse current, and reduce the required magnetization or demagnetization current pulse amplitude.

[0044] The number of first permanent magnets 22 and sector-shaped magnetic barriers 24 is the same and both are even numbers. The number of second permanent magnets 23 is twice the number of first permanent magnets 22. For the technical solution of this application, the number of first permanent magnets 22 and sector-shaped magnetic barriers 24 is 4, and the number of second permanent magnets 23 is 8.

[0045] On the other hand, the first permanent magnet 22 is a low coercivity permanent magnet, and the second permanent magnet 23 is a high coercivity permanent magnet. In the technical solution of this application, the first permanent magnet 22 is an AlNiCo permanent magnet, and the second permanent magnet 23 is a NdFeB permanent magnet.

[0046] Combination Figure 4 and Figure 5 The operating principle of this embodiment is as follows: the permanent magnet flux first starts from the N pole of the circumferentially distributed second permanent magnet 23. If the magnetization direction of the first permanent magnet 22 is the same as the magnetization direction of the second permanent magnet 23 with the same pole, then the first permanent magnet 22 is in a magnetization state. The magnetic flux of the first permanent magnet 22 and the second permanent magnet 23 merges, passes through the rotor core 21, passes through the air gap, reaches the stator tooth 14, passes through the stator yoke 13, and then returns to the S pole of the adjacent second permanent magnet 23 and the S pole of the adjacent first magnet 22 in reverse order along the same path.

[0047] If the magnetization direction of the first permanent magnet 22 is opposite to the magnetization direction of the second permanent magnet 23 at the same pole, then the first permanent magnet 22 is in a demagnetized state. Part of the magnetic flux of the reverse-magnetized first permanent magnet 22 is canceled out by the second permanent magnet 23 at the end, and the other part starts from the N pole, passes through the rotor core 21, through the air gap, reaches the stator teeth 14, passes through the stator yoke 13, and then returns to the S pole of the adjacent first permanent magnet 22 in the reverse order along the same path. The magnetic field lines of the motor are distributed as follows when the first permanent magnet 22 is in either of the two magnetization states: Figure 4 and Figure 5 As shown, the sector-shaped magnetic barrier 24 between adjacent poles can effectively reduce the quadrature-axis inductance, making the motor exhibit anti-salient pole characteristics where the direct-axis inductance is greater than the quadrature-axis inductance. Under load, the armature current has a magnetizing effect on the low-coercivity permanent magnet, thereby improving the low-coercivity permanent magnet's resistance to load demagnetization. The operating points of the low-coercivity permanent magnet before and after the load are as follows: Figure 6 As shown, the stability of the operating point of the low coercivity permanent magnet is guaranteed, and the operating point is slightly improved.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0051] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor, comprising: Stator (1), the stator (1) includes a stator core (11), on which an armature winding (12) is mounted; Hybrid permanent magnet rotor (2), which is rotatably connected inside the stator (1); The hybrid permanent magnet rotor (2) includes a rotor core (21), on which a plurality of first permanent magnets (22) are mounted, and the plurality of first permanent magnets (22) are evenly distributed circumferentially at the outer edge of the rotor core (21); The first permanent magnet (22) has a second permanent magnet (23) installed at both ends, and the coercivity of the first permanent magnet (22) is less than that of the second permanent magnet (23); The rotor core (21) is provided with multiple fan-shaped magnetic barriers (24), and the multiple fan-shaped magnetic barriers (24) are evenly distributed on the rotor core (21) in the circumferential direction; The opening of the sector magnetic barrier (24) faces the outer edge of the rotor core (21). Each sector magnetic barrier (24) is located between two adjacent first permanent magnets (22), and the axis of symmetry of the sector magnetic barrier (24) coincides with the axis of symmetry of the two adjacent first permanent magnets (22). The first permanent magnet (22) is a low coercivity permanent magnet, and the cross-section of the first permanent magnet (22) is arranged in a straight line. The first permanent magnet (22) is bidirectionally magnetized, and the magnetization direction is parallel to the length direction of its short side. The magnetization directions between adjacent first permanent magnets (22) are always opposite. The second permanent magnet (23) is unidirectionally magnetized, and its magnetization direction is parallel to the magnetization direction of the first permanent magnet (22) under the same magnetic pole.

2. The magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 1, characterized in that: The stator (1) and the hybrid permanent magnet rotor (2) are arranged coaxially, and an air gap is uniformly provided between the stator (1) and the hybrid permanent magnet rotor (2).

3. The magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 2, characterized in that: A rotating shaft (3) is installed at the center of the hybrid permanent magnet rotor (2).

4. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 3, characterized in that: The second permanent magnet (23) is a high coercivity permanent magnet, and the cross-section of the second permanent magnet (23) is arranged in a straight line.

5. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 4, characterized in that: The magnetization directions of the two second permanent magnets (23) under the same magnetic pole are the same, and the magnetization directions of the two second permanent magnets (23) under adjacent magnetic poles are always opposite.

6. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 5, characterized in that: The first permanent magnet (22) and the second permanent magnet (23) form a parallel magnetic circuit. When the magnetization directions of the first permanent magnet (22) and the second permanent magnet (23) are the same in the same magnetic pole, the motor is in the magnetization state; otherwise, the motor is in the demagnetization state.

7. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 1, characterized in that: The number of the first permanent magnet (22) and the sector magnetic barrier (24) is the same and both are even numbers. The number of the second permanent magnet (23) is twice the number of the first permanent magnet (22).

8. A magnetic field-enhanced parallel magnetic circuit variable flux memory motor according to claim 1, characterized in that: The first permanent magnet (22) is an AlNiCo permanent magnet, and the second permanent magnet (23) is a NdFeB permanent magnet.

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