Rotor structure, electric machine and automobile

Abstract

The application discloses a rotor structure, a motor and a car and belongs to the technical field of rotor topology. The rotor structure comprises a rotor core and a plurality of magnetic poles which are uniformly arranged along the circumference of the rotor core. The magnetic pole comprises an inner layer permanent magnet group and an outer layer permanent magnet group which are radially inward in the opening direction. The harmonic magnetic fields generated by the inner layer permanent magnet group and the outer layer permanent magnet group are mutually offset. The magnetomotive forces of the inner layer permanent magnet group and the outer layer permanent magnet group are superposed in the same direction to form a magnetic circuit series branch. The independent magnetic flux paths on both sides of the magnetic pole form a magnetic circuit parallel branch for magnetic flux shunting. The hybrid magnetic circuit improves the direct-axis and quadrature-axis inductance characteristics of the motor, widens the constant-power speed regulation range of the motor in combination with excellent demagnetization resistance, and improves the high-speed running efficiency.

Description

Technical Field

[0001] This invention relates to the field of rotor topology technology, and particularly to a rotor structure, motor, and automobile. Background Technology

[0002] Compared to the straight magnet structure, the mainstream V-shaped built-in permanent magnet topology can form a more uniform and symmetrical q-axis magnetic circuit, effectively improving the salient pole ratio. Combined with the magnetic focusing effect of the arc-shaped magnet, it can improve the air gap magnetic density and obtain higher permanent magnet torque.

[0003] However, due to the severe distortion of the air gap magnetic flux density waveform in traditional single-layer series permanent magnet synchronous motors, which contain a large number of 5th and 7th spatial harmonics, the interaction between the 5th and 7th harmonics and the stator armature magnetic field generates electromagnetic torque pulsation and radial electromagnetic force at the 6th frequency, inducing vibration of the generator stator structure and increasing electromagnetic noise.

[0004] Moreover, under heavy load and high-speed weak magnetic conditions, the permanent magnet's demagnetization capability is insufficient to achieve magnetic flux diversion, the magnetic conduction area is greatly reduced, and at the same time, the rotor core is partially magnetically saturated, the core loss increases sharply, resulting in low operating efficiency. Summary of the Invention

[0005] Purpose of the invention: In view of the above problems, the purpose of this invention is to provide a rotor structure, a motor, and an automobile.

[0006] Technical solution: In a first aspect, a rotor structure of the present invention includes a rotor core and a plurality of magnetic poles uniformly arranged along the circumference of the rotor core.

[0007] Because traditional single-layer series permanent magnet synchronous motors have severe distortion of air gap magnetic flux density waveform, containing a large number of 5th and 7th spatial harmonics, and the interaction between the 5th and 7th harmonics and the stator armature magnetic field generates 6th frequency electromagnetic torque pulsation and radial electromagnetic force, which induces vibration of the generator stator structure and increases electromagnetic noise.

[0008] To address this issue, the present invention provides an inner permanent magnet group and an outer permanent magnet group with the opening direction radially inward. The harmonic magnetic fields generated by the inner permanent magnet group and the outer permanent magnet group cancel each other out, thereby reducing the distortion of the air gap magnetic field.

[0009] Furthermore, considering that the traditional single-layer series structure has only one layer, the armature reaction magnetic field directly acts on the permanent magnet, resulting in insufficient resistance to demagnetization; this technical solution uses the magnetomotive force of the inner permanent magnet group and the outer permanent magnet group to be superimposed in the same direction to form a series branch of the magnetic circuit, thereby balancing the operating point of the permanent magnet and significantly improving the resistance to irreversible demagnetization of the permanent magnet under heavy load and high-speed weak magnetic conditions.

[0010] Furthermore, considering the low design freedom of single-layer magnetic circuits, it is difficult to simultaneously optimize the air gap magnetic flux density waveform and torque density, which can easily lead to problems such as local core saturation, excessive harmonics, and high torque pulsation. Based on the above solution, a parallel branch of the magnetic circuit is formed by independent magnetic flux paths on both sides of the magnetic poles to achieve magnetic flux shunting, increase the effective magnetic conduction area, improve the fundamental magnetic flux density of the air gap and the torque density of the motor, and at the same time alleviate local magnetic saturation of the rotor core and reduce core losses.

[0011] In summary, the rotor structure of this invention solves the problem of reducing electromagnetic noise while employing a hybrid series-parallel configuration. The series branch ensures the operational stability and demagnetization resistance of the permanent magnets, while the parallel branch provides sufficient main magnetic flux for output torque. Compared to a single-layer series structure, it offers higher average air gap magnetic flux density for the same amount of permanent magnets; stronger demagnetization resistance under heavy load and weak magnetic conditions; and a better air gap magnetic flux density waveform with less torque ripple, effectively improving output torque.

[0012] As an example, the rotor structure is a 4-pole built-in permanent magnet structure, with each pole configured with an inner V-shaped permanent magnet and an outer permanent magnet assembly. This is illustrated in the accompanying drawings of the specification. Figure 3 As shown, the V-shaped permanent magnet is composed of strip permanent magnets 2-4 and 2-5, and together with the second arc-shaped permanent magnets 2-6, 2-8 and the second arc-shaped permanent magnets 2-7 and 2-9 arranged on both sides thereon, it forms the inner permanent magnet group; while the outer permanent magnet group is composed of the first arc-shaped permanent magnets 2-1, 2-2 and 2-3.

[0013] Specifically, by limiting the inner and outer permanent magnet groups to be offset by 30° to 40° electrical angle in the circumferential direction, the 5th and 7th harmonic magnetic fields generated by the inner strip permanent magnets 2-4 and 2-5 and the second arc permanent magnets 2-8 and 2-9 are 180° out of phase with the 5th and 7th harmonic magnetic fields generated by the outer first arc permanent magnets 2-1, 2-2, and 2-3. At the same time, the radial spacing between the inner and outer permanent magnets is controlled to be 1 / 6 to 1 / 4 of the radial dimension of the rotor pole pitch, ensuring that the amplitudes of the two sets of harmonic magnetic fields are close when they are transmitted to the air gap.

[0014] Under the combined constraints of the aforementioned angle and radial spacing, the harmonic magnetic field generated by the inner permanent magnet cancels out the harmonic magnetic field generated by the outer permanent magnet, reducing the distortion of the air gap magnetic field.

[0015] Furthermore, the magnetic circuit is connected in series through the second arc-shaped permanent magnet 2-8 in the inner layer and the first arc-shaped permanent magnet 2-1 in the outer layer. The magnetomotive forces of the two permanent magnets support each other, balance the working point of the permanent magnets, and significantly improve the permanent magnets' resistance to irreversible demagnetization under heavy load and high-speed weak magnetic conditions.

[0016] The magnetic circuit is formed by two parallel branches of magnetic flux paths on the left and right sides of the same magnetic pole. Specifically, the magnetic flux on the left flows from the second arc-shaped permanent magnet 2-8 into the strip permanent magnet 2-4 and finally into the first arc-shaped permanent magnet 2-2 to form an independent magnetic flux channel. On the right side, the magnetic flux flows from the second arc-shaped permanent magnet 2-9 into the strip permanent magnet 2-5 and finally into the first arc-shaped permanent magnet 2-2 to form another independent magnetic flux channel. This achieves magnetic flux shunting, increases the effective magnetic conduction area, improves the fundamental magnetic flux density of the air gap and the torque density of the motor, and at the same time alleviates local magnetic saturation of the rotor core and reduces core loss.

[0017] In a second aspect, the present invention provides an electric motor, including a motor rotor, wherein the motor rotor is the motor rotor described in the first aspect.

[0018] Thirdly, an automobile includes an electric motor, said electric motor being the type described in the second aspect.

[0019] Beneficial effects:

[0020] The significant advantages of this invention compared to existing technologies are:

[0021] 1. This invention ensures that the 5th and 7th harmonic magnetic fields generated by the inner permanent magnet are out of phase and have similar amplitudes to those generated by the outer permanent magnet, causing the two types of harmonics to cancel each other out, thereby reducing the content of the 5th and 7th harmonics in the air gap magnetic flux density. Simultaneously, the series-parallel hybrid magnetic circuit smooths out abrupt changes in magnetic flux at the pole edges, alleviating local magnetic saturation in the rotor core and further suppressing harmonic generation. As a result, the sinusoidal nature of the air gap magnetic flux density waveform is improved, significantly reducing torque pulsation and radial electromagnetic force caused by the 5th and 7th harmonics, ultimately reducing motor vibration and electromagnetic noise.

[0022] 2. This invention optimizes the air gap flux distribution through a hybrid magnetic circuit consisting of series and parallel branches, suppressing torque fluctuations caused by harmonics and cogging effects, reducing torque pulsation, and making the motor output torque more stable; it also improves the motor's direct and quadrature axis inductance characteristics, combined with excellent anti-demagnetization performance, to broaden the constant power speed regulation range of the motor and improve high-speed operation efficiency. Attached Figure Description

[0023] Figure 1 This is a radial cross-sectional view of the rotor structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the permanent magnet slot structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the permanent magnet and its magnetization direction of the present invention;

[0026] Figure 4 This is a schematic diagram of the motor magnetic circuit of the present invention;

[0027] Figure 5This is a schematic diagram of the no-load back electromotive force waveform of the motor according to the present invention;

[0028] Figure 6 This is a comparison diagram of the output torque waveforms of the motor of the present invention and a conventional motor.

[0029] Figure 7 This is a comparison diagram of the air gap magnetic flux density waveforms of the motor of this invention and a conventional motor.

[0030] Figure 8 This is a FFT comparison diagram of the air gap magnetic flux density of the motor of the present invention and that of a conventional motor.

[0031] The meanings of the various reference numerals in the attached figures are as follows:

[0032] 1. Rotor core; 2. Permanent magnet; 3. Magnetic barrier; 4. Shaft; 6. Stator; 7. Winding. Detailed Implementation

[0033] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the embodiments of the present invention, and not all structures.

[0034] In the following description, specific details such as target system architecture and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0035] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0036] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] Furthermore, in the description of this application and the appended claims, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include the target features, structures, or characteristics described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0039] Figure 1 The rotor structure shown is that of a series-parallel hybrid permanent magnet synchronous motor. See [link / reference]. Figure 1 The rotor structure includes a rotor core 1, a permanent magnet 2, a magnetic barrier 3, and a rotating shaft 4.

[0040] See Figure 1 and Figure 2 The rotor core 1 has four sets of symmetrical permanent magnet mounting slots evenly distributed along the circumference. All four sets of symmetrical permanent magnet mounting slots are circumferentially symmetrical structures, and the opening direction of the overall structure is radially inward.

[0041] See Figure 2 Each permanent magnet mounting slot consists of two equal-sized first arc-shaped permanent magnet slots 5-1 and 5-3 near the outer side of the rotor, and a second arc-shaped permanent magnet slot 5-2 connecting these two slots in series. The outer side consists of two sets of symmetrical and identical third arc-shaped permanent magnet slots 5-6, 5-7, 5-8, and 5-9. The third arc-shaped permanent magnet slots 5-6 and 5-8 have the same opening direction, as do the third arc-shaped permanent magnet slots 5-7 and 5-9. Furthermore, the opening directions of adjacent sets of third arc-shaped permanent magnet slots alternate between facing each other and facing away from each other (in conjunction with...). Figure 1 (as shown); while the permanent magnet mounting groove forms the interior of the integral structure, which is composed of two strip permanent magnet grooves 5-4 and 5-5 of the same size connected to form a V-shaped permanent magnet groove.

[0042] See Figure 2 and Figure 3 First arc-shaped permanent magnets 2-1, 2-2, and 2-3 are fixedly embedded in the first arc-shaped permanent magnet grooves 5-1 and 5-3 and the second arc-shaped permanent magnet groove 5-2. Two strip-shaped permanent magnets 2-4 and 2-5 are fixedly embedded in the strip-shaped permanent magnet grooves 5-4 and 5-5. Second arc-shaped permanent magnets 2-6, 2-7, 2-8, and 2-9 are fixedly embedded in the two pairs of third arc-shaped permanent magnet grooves 5-6, 5-7, 5-8, and 5-9 on the outer side.

[0043] See Figure 1 Magnetic barriers 3 are arranged in the rotor core 1 between two adjacent arc-shaped / strip-shaped permanent magnet slots. Magnetic barriers 3 are also arranged in the rotor core 1 at both ends of a single arc-shaped permanent magnet slot.

[0044] Preferably, the magnetic barriers 3 are all made of epoxy resin-based composite materials.

[0045] Preferably, the permanent magnet is made of rare earth neodymium iron boron material, with remanence and coercivity of 1.19T and 920kA / m, respectively.

[0046] See Figure 3 When the strip permanent magnets 2-4 and 2-5 in the strip permanent magnet slots 5-4 and 5-5 are magnetized radially outward, the three arc-shaped permanent magnets 2-1, 2-2, and 2-3 in the permanent magnet slots 5-1, 5-2, and 5-3 are magnetized in the same direction, all facing the outside of the rotor (air gap side). When the strip permanent magnets 2-4 and 2-5 are magnetized radially inward, then correspondingly, the three arc-shaped permanent magnets 2-1, 2-2, and 2-3 in the permanent magnet slots 5-1, 5-2, and 5-3 are magnetized in the same direction, all facing the inside of the rotor.

[0047] See Figure 3 The two V-shaped permanent magnets 2-4 and 2-5 within the strip permanent magnet slots 5-4 and 5-5 are a set of opposing permanent magnets. The four sets of arc-shaped permanent magnets on the rotor circumference are magnetized in a tangentially alternating manner. Specifically, when the strip permanent magnets 2-4 and 2-5 within the strip permanent magnet slots 5-4 and 5-5 are magnetized radially inward, the magnetization direction of the two sets of second arc-shaped permanent magnets 2-6, 2-7, 2-8, and 2-9 within the slot is opposite to the direction of the arc-shaped opening, specifically tangentially opposite. When the strip permanent magnets 2-4 and 2-5 are magnetized radially outward, the corresponding magnetization direction of the two sets of second arc-shaped permanent magnets 2-6, 2-7, 2-8, and 2-9 is the same as the direction of the arc-shaped opening, specifically tangentially opposite (i.e.,...). Figure 3 (Example scenario).

[0048] Working principle:

[0049] The rotor has four magnetic poles evenly arranged circumferentially. Each magnetic pole is equipped with an inner V-shaped permanent magnet and an arc-shaped permanent magnet group (second arc-shaped permanent magnets 2-6, 2-8 and second arc-shaped permanent magnets 2-7, 2-9) placed on both sides. The rotor core 1 has permanent magnet mounting slots that match the shape of the permanent magnets. Magnetic isolation slots and magnetic guiding bridges are retained between the permanent magnet mounting slots. Two sets of permanent magnets are symmetrically arranged under the same magnetic pole, namely the second arc-shaped permanent magnet 2-8, the first arc-shaped permanent magnet 2-1, the second arc-shaped permanent magnet 2-9, and the first arc-shaped permanent magnet 2-3. The magnetic flux is split by the second arc-shaped permanent magnets 2-8 and 2-9, flowing into the first permanent magnets 2-1 and 2-2 near the air gap on the outside of the rotor, and each flows independently into the air gap. The other part flows into the built-in V-shaped permanent magnets (strip permanent magnets 2-4 and 2-5) and finally the magnetic flux converges and flows together into the air gap through the first arc-shaped permanent magnet 2-2.

[0050] See Figure 4 The stator 6 is coaxially assembled with the rotor. Three-phase alternating current is applied to the armature winding 7 of the stator 6 to generate a rotating armature magnetic field, which interacts with the excitation magnetic field established by the rotor permanent magnets to realize electromechanical energy conversion. The magnetic isolation slots of the rotor core 1 constrain the leakage magnetic flux between the permanent magnets inside the rotor, and the magnetic conduction area guides the magnetic flux to flow along a preset path to ensure the stable formation of the series and parallel magnetic circuit topology.

[0051] Among them, the magnetic circuit series is the internal magnetic flux path, that is, from the inner iron core of the rotor to the inner second arc permanent magnet 2-8, then to the outer first arc permanent magnet 2-1, then to the magnetic field area of ​​the iron core outside the magnetic pole, and finally to the air gap. The magnetic flux passes through the inner and outer permanent magnets one after another. The magnetomotive forces of the two permanent magnets are superimposed in the same direction, forming the magnetic circuit series branch.

[0052] The parallel magnetic circuit is composed of two magnetic flux paths on the left and right sides under the same magnetic pole. Specifically, the magnetic flux on the left flows from the second arc-shaped permanent magnet 2-8 into the strip permanent magnet 2-4 and finally into the first arc-shaped permanent magnet 2-2 to form an independent magnetic flux channel. On the right side, the magnetic flux flows from the second arc-shaped permanent magnet 2-9 into the strip permanent magnet 2-5 and finally into the first arc-shaped permanent magnet 2-2 to form another independent magnetic flux channel. The two channels do not interfere with each other. After the two magnetic fluxes finally merge, they enter the air gap together. The two paths are parallel magnetic flux branches.

[0053] like Figure 5 The time-domain waveforms of the three-phase no-load back EMF of the motor shown are as follows: the phases of the back EMFs A, B, and C phases differ by 120° electrical angle, and the amplitudes of the three-phase waveforms are basically consistent, exhibiting good three-phase symmetry. The overall waveforms approximate a sine wave, with no obvious distortion, glitches, or spikes, indicating that the low-order harmonics of the motor's air gap magnetic field are effectively suppressed. Excellent no-load back EMF waveforms can reduce motor torque pulsation and cogging torque, decrease electromagnetic vibration and noise, reduce harmonic losses, and improve the motor's steady-state operating performance.

[0054] like Figure 6 and Figure 7 As shown, the air gap magnetic flux density waveform and output torque curves obtained from simulations of the permanent magnet synchronous motor proposed in this invention and the traditional V-type permanent magnet synchronous motor are presented. The simulation models of the two motor structures have the same rotor core inner and outer diameters, the same winding volume, the same permanent magnet material, and the same permanent magnet volume (285.1). The rotor core volume of this invention is 13212.5 mm. Its volume is slightly smaller than that of a V-type rotor core (13214.2). Simulation data shows that, compared with the V-type permanent magnet synchronous motor, the amplitude of the air gap magnetic flux density of the permanent magnet synchronous motor proposed in this invention increases from 0.65T to 1.23T, an increase of 89.23%. Combined with... Figure 8As shown, FFT analysis of the air gap magnetic flux density reveals that the 5th and 7th harmonics in the air gap magnetic flux density of the motor of this invention are reduced. Under the same excitation current (excitation current is 100*1.414*sin(2*pi*100*time)), the average output torque increases from 1.25Nm to 3.45Nm, effectively improving the output torque.

[0055] According to an embodiment of the present invention, an electric motor is also provided, including the rotor structure described above.

[0056] According to an embodiment of the present invention, a new energy vehicle is also provided, including the motor described above.

[0057] For example, the powertrain system of a new energy passenger vehicle includes a power battery, a motor controller, a reducer, and a drive motor. The drive motor can adopt the aforementioned double-layer nested V-shaped series-parallel hybrid magnetic circuit permanent magnet rotor structure, which has the following advantages:

[0058] When the vehicle is continuously traveling at high speed, the motor is in a weak magnetic field operation state, and the armature reaction demagnetization magnetic field is strong; the series magnetic circuit structure in the support arm enhances the permanent magnet's resistance to demagnetization and prevents the permanent magnet from demagnetizing and failing under long-term high-speed conditions.

[0059] Passenger vehicles are sensitive to cab vibration and noise. The rotor structure of this invention effectively suppresses the 5th and 7th harmonics of the air gap magnetic flux, reduces electromagnetic vibration and noise excited by harmonics, reduces noise transmitted to the cab, and improves driving comfort.

[0060] For frequent acceleration and deceleration conditions, the rotor structure of this invention has less torque pulsation, smoother power output, reduced impact on the transmission system, and extended service life of transmission components such as reducers and half shafts.

[0061] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the scope of protection of the present invention also includes various modifications or variations made by those skilled in the art within the scope of the claims.

Claims

1. A rotor structure comprising a rotor core and a plurality of magnetic poles uniformly arranged circumferentially along the rotor core, characterized in that, The magnetic poles include an inner layer permanent magnet group and an outer layer permanent magnet group arranged radially inwards and outwards, and the harmonic magnetic fields generated by the inner layer permanent magnet group and the outer layer permanent magnet group cancel each other out; The magnetomotive forces of the inner permanent magnet group and the outer permanent magnet group are superimposed in the same direction, forming a magnetic circuit series branch; The independent magnetic flux paths on both sides of the magnetic pole form parallel branches of the magnetic circuit, which are used for magnetic flux splitting.

2. The rotor structure according to claim 1, characterized in that, The inner permanent magnet assembly and the outer permanent magnet assembly are offset by 30° to 40° electrical angle in the circumferential direction.

3. The rotor structure according to claim 2, characterized in that, The radial distance between the permanent magnet assembly and the outer permanent magnet assembly is 1 / 6 to 1 / 4 of the radial dimension of the rotor pole pitch.

4. The rotor structure according to any one of claims 1 to 3, characterized in that, The outer permanent magnet assembly includes a first arc-shaped permanent magnet (2-1, 2-2, 2-3) disposed near the air gap side; the inner permanent magnet assembly includes a V-shaped permanent magnet with its opening facing the air gap side and a second arc-shaped permanent magnet (2-6, 2-8) and a second arc-shaped permanent magnet (2-7, 2-9) disposed on both sides of the V-shaped permanent magnet.

5. The rotor structure according to claim 4, characterized in that, The V-shaped permanent magnet is composed of bar permanent magnets (2-4, 2-5).

6. The rotor structure according to claim 5, characterized in that, The strip permanent magnets (2-4, 2-5) are a group of opposing permanent magnets.

7. The rotor structure according to claim 6, characterized in that, The second arc-shaped permanent magnet adopts a tangential alternating magnetization method.

8. The rotor structure according to claim 4, characterized in that, Magnetic barriers are arranged in the rotor core between the second arc-shaped permanent magnet (2-8, 2-9) and the first arc-shaped permanent magnet (2-1, 2-2, 2-3); magnetic barriers are arranged in the rotor core at both ends of the second arc-shaped permanent magnet (2-6, 2-7).

9. An electric motor, comprising a rotor structure, characterized in that, The rotor structure is the rotor structure according to any one of claims 1 to 3.

10. A motor vehicle, comprising an electric motor, characterized in that, The motor is the motor described in claim 9.

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