Motor rotors, reluctance motors and electric vehicles

Abstract

The present application provides a motor rotor, a reluctance motor and an electric vehicle. The motor rotor comprises a rotor core (1), a plurality of magnetic barrier groups are arranged circumferentially on the rotor core (1), each magnetic barrier group comprises at least two magnetic flux barriers (2) arranged radially, a magnetic conductive channel (3) is formed between adjacent magnetic flux barriers (2), in a cross section perpendicular to the central axis of the rotor core (1), the magnetic flux barriers (2) located radially on the outermost side under the same pole form a groove, and a straight-line mounting groove (4) is provided on the rotor core in the groove, the mounting groove (4) comprises a first groove portion (5) located at a first end and a second groove portion (6) located at a second end, the first groove portion (5) and the second groove portion (6) are connected, and the radial thickness of the first groove portion (5) and the second groove portion (6) are different. According to the motor rotor of the present application, a basically sinusoidal and symmetrically distributed air gap magnetic density waveform can be obtained under load, thereby reducing the motor torque pulsation and iron loss.

Description

Technical Field

[0001] The present application relates to the technical field of motor equipment, and in particular to a motor rotor, a reluctance motor and an electric vehicle. Background Art

[0002] Industrial motors are widely used in fans, pumps, and general machinery. Currently, IE2 asynchronous motors are still the dominant technology, due to their low efficiency, large size, and complex manufacturing process. In some high-efficiency applications, permanent magnet synchronous motors (IPMs) can achieve IE4 or higher efficiency. However, rare earth permanent magnet motors require a large amount of rare earth permanent magnet material, resulting in high costs and slow adoption.

[0003] Permanent magnet motors experience armature reaction during operation. Under no-load conditions, the permanent magnets are symmetrically distributed along the centerline of the poles, resulting in a symmetrical magnetic flux density distribution. However, under armature reaction, the interaction between the no-load magnets and the stator magnetic field causes the magnetic flux density distribution of the permanent magnets to become uneven, resulting in partial magnetization and partial demagnetization. The magnetic flux density distribution under load often determines the level of motor noise and torque ripple. Therefore, this air gap magnetic flux distortion caused by armature reaction affects the sinusoidal nature of the air gap magnetic flux waveform and increases torque ripple and iron losses in the motor. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present application is to provide a motor rotor, a reluctance motor and an electric vehicle, which can obtain a basically sinusoidal and symmetrically distributed air gap magnetic flux waveform under load conditions, thereby reducing the motor torque pulsation and iron loss.

[0005] In order to solve the above problems, the present application provides a motor rotor, including a rotor core, and a plurality of magnetic barrier groups are arranged circumferentially on the rotor core, each magnetic barrier group includes at least two magnetic flux barriers arranged radially, and a magnetic conductive channel is formed between adjacent magnetic flux barriers. In a cross section perpendicular to the central axis of the rotor core, the magnetic flux barriers located at the radially outermost side under the same pole form a groove, and the rotor core in the groove has a straight-line mounting groove, and the mounting groove includes a first groove portion located at the first end and a second groove portion located at the second end, the first groove portion and the second groove portion are connected to each other, and the radial thickness of the first groove portion and the second groove portion are different.

[0006] Preferably, the first groove portion and the second groove portion have different lengths.

[0007] Preferably, the thickness of the first groove portion is greater than the thickness of the second groove portion.

[0008] Preferably, the length of the first groove portion is greater than the length of the second groove portion.

[0009] Preferably, a first permanent magnet is disposed in the first slot portion, and a second permanent magnet is disposed in the second slot portion, and the coercive force of the first permanent magnet is greater than the coercive force of the second permanent magnet.

[0010] Preferably, the first permanent magnet is a rare earth permanent magnet, and the second permanent magnet is a ferrite permanent magnet.

[0011] Preferably, the thickness of the first permanent magnet is W1, the thickness of the second permanent magnet is W2, wherein W1 / W2=1.5-2.0; and / or the length of the first permanent magnet is L1, the length of the second permanent magnet is L2, wherein L1 / L2=1.2-1.8.

[0012] Preferably, the magnetic channel occupancy rate δ satisfies 0.32≤δ≤0.38 or 0.54≤δ≤0.63.

[0013] Preferably, the magnetic channel occupancy rate is determined by the following formula:

[0014] δ=1-(w1+w3+w5) / (w1+w2+w3+w4+w5+2w6)

[0015] Where w1 is the thickness of the radially outermost flux barrier, w2 is the thickness of the magnetic conductive channel adjacent to the radially outermost flux barrier, and so on. w6 is the thickness of the iron core between the circumferential outer wall of the radially innermost flux barrier under the same pole and the circumferential outer wall of the pole.

[0016] Preferably, the pole arc coefficient of the permanent magnet in the installation slot is A0, where 0.35≤A0≤0.46; and / or, the pole arc coefficient of the permanent magnet in the installation slot is A0, the pole arc coefficient of the magnetic channel adjacent to the radially outermost magnetic flux barrier is A1, and the pole arc coefficient of the adjacent magnetic channel located circumferentially outside the magnetic channel is A2, where A2-A1>A1-A0.

[0017] According to another aspect of the present application, a reluctance motor is provided, comprising a motor rotor and a motor stator, wherein the motor rotor is the above-mentioned motor rotor.

[0018] According to another aspect of the present application, an electric vehicle is provided, comprising the above-mentioned motor rotor or the above-mentioned reluctance motor.

[0019] The motor rotor provided in the present application includes a rotor core, wherein a plurality of magnetic barrier groups are arranged circumferentially on the rotor core, each magnetic barrier group including at least two magnetic flux barriers arranged radially, with a magnetic conductive channel formed between adjacent magnetic flux barriers. In a cross section perpendicular to the central axis of the rotor core, the magnetic flux barriers located radially outermost under the same pole form a groove, and the rotor core within the groove has a straight-line mounting groove, the mounting groove including a first groove portion located at a first end and a second groove portion located at a second end, the first groove portion and the second groove portion being interconnected, and the first groove portion and the second groove portion having different radial thicknesses. By splitting the straight-line mounting groove, the straight-line mounting groove forms a first groove portion and a second groove portion having different radial thicknesses, permanent magnets of different thicknesses can be respectively arranged in the first groove portion and the second groove portion, thereby enabling different anti-demagnetization capabilities to be formed using permanent magnets of different thicknesses, and forming a combined permanent magnet structure, thereby obtaining a basically sinusoidal and symmetrically distributed air gap flux waveform under load, thereby reducing motor torque pulsation and iron loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the motor rotor according to an embodiment of the present application;

[0021] Figure 2 This is a first size structural diagram of the motor rotor according to an embodiment of the present application;

[0022] Figure 3 This is a second size structural diagram of the motor rotor according to an embodiment of the present application;

[0023] Figure 4 This is a schematic diagram of the magnetic lines of force of the motor rotor when ID=0 according to an embodiment of the present application;

[0024] Figure 5 Schematic diagram of magnetic lines of force of the motor rotor when ID<0 according to an embodiment of the present application;

[0025] Figure 6 Schematic diagram of magnetization and demagnetization of the motor rotor according to an embodiment of the present application;

[0026] Figure 7 A graph showing the relationship between the output of the motor rotor and the occupancy rate of the magnetic conductive channel according to an embodiment of the present application;

[0027] Figure 8 A curve diagram showing the relationship between the torque ripple coefficient and A0 of the motor rotor in an embodiment of the present application;

[0028] Figure 9 This is a comparison diagram of the load air gap magnetic flux density curves of the motor rotor according to the embodiment of the present application and the prior art.

[0029] The reference numerals indicate:

[0030] 1. Rotor core; 2. Magnetic flux barrier; 3. Magnetic channel; 4. Mounting slot; 5. First slot portion; 6. Second slot portion; 7. First permanent magnet; 8. Second permanent magnet. DETAILED DESCRIPTION

[0031] See also Figures 1 to 9 As shown, according to an embodiment of the present application, the motor rotor includes a rotor core 1, and a plurality of magnetic barrier groups are arranged circumferentially on the rotor core 1, each magnetic barrier group includes at least two magnetic flux barriers 2 arranged radially, and a magnetic conductive channel 3 is formed between adjacent magnetic flux barriers 2. In a cross section perpendicular to the central axis of the rotor core 1, the magnetic flux barriers 2 located at the radially outermost side under the same pole form a groove, and the rotor core 1 in the groove has a straight-line mounting groove 4, which includes a first groove portion 5 located at a first end and a second groove portion 6 located at a second end. The first groove portion 5 and the second groove portion 6 are connected to each other, and the radial thickness of the first groove portion 5 and the second groove portion 6 are different.

[0032] The motor rotor of the present application splits the I-shaped mounting groove 4 so that the I-shaped mounting groove 4 forms a first groove portion 5 and a second groove portion 6 with different radial thicknesses. Permanent magnets of different thicknesses can be respectively arranged in the first groove portion 5 and the second groove portion 6, so that different anti-demagnetization capabilities can be formed by using permanent magnets of different thicknesses. A combined permanent magnet structure can be formed to obtain a basically sinusoidal and symmetrically distributed air gap magnetic flux waveform under load conditions, thereby reducing motor torque pulsation and iron loss.

[0033] The mounting slot 4 is bisected by the pole center line in the length direction, so that the lengths of the permanent magnets on both sides of the pole center line are the same.

[0034] The flux barrier 2 is formed by an air slot, and the shape of the flux barrier 2 can be U-shaped, inverted trapezoidal or other shapes.

[0035] Preferably, the lengths of the first slot portion 5 and the second slot portion 6 are different, so that the lengths of permanent magnets of different thicknesses can be reasonably distributed, so that permanent magnets of different thicknesses can select appropriate matching lengths, which can make it easier to obtain a basically sinusoidal and symmetrically distributed air gap magnetic flux waveform under load.

[0036] In this embodiment, the thickness of the first groove portion 5 is greater than the thickness of the second groove portion 6 .

[0037] The length of the first groove portion 5 is greater than the length of the second groove portion 6 .

[0038] Preferably, a first permanent magnet 7 is disposed in the first slot 5 , and a second permanent magnet 8 is disposed in the second slot 6 . The coercive force of the first permanent magnet 7 is greater than the coercive force of the second permanent magnet 8 .

[0039] The thickness of the first permanent magnet 7 is W1, and the thickness of the second permanent magnet 8 is W2, wherein W1 / W2=1.5-2.0.

[0040] The length of the first permanent magnet 7 is L1, and the length of the second permanent magnet 8 is L2, wherein L1 / L2=1.2-1.8.

[0041] pass Figure 4 It can be found that under the control of ID=0, when no reluctance torque is generated, the armature reaction magnetic lines of force interact with the permanent magnet magnetic field, and half of the permanent magnet of each pole is magnetized and the other half is demagnetized. The front pole is magnetized and the rear pole is demagnetized (the default rotation direction is counterclockwise, where the front part of the rotation direction of each pole is the front pole and the other part is the rear pole). The permanent magnet assisted reluctance motor needs to be weakened to maximize the synthetic torque, so the armature magnetic field must be further ahead of the rotor by one angle based on ID=0. Figure 5 As shown in the figure, the area of ​​the permanent magnets to be demagnetized is larger, exceeding half. At this time, the magnetic field of the armature reaction changes from the original symmetrical distribution to an asymmetrical distribution, affecting the sinusoidal distribution of the motor's back EMF.

[0042] To address this issue, the present embodiment of the present invention designs L1 to be greater than L2, with the ratio between the two ranging from 1.2 to 1.8. This effectively utilizes the first permanent magnet 7 to offset the demagnetizing effect of the stator magnetic field on the permanent magnets. When L1 is too small, the weakening angle increases, which is insufficient to fully offset the weakening magnetic field. When L1 is too large, the ferrite portion accounts for too high a proportion, reducing the permanent magnet characteristics of the entire motor and affecting the motor's output.

[0043] Since the coercive force of the second permanent magnet 8 is relatively low, W1>W2 is designed, and the ratio of W1 to W2 is within the range of 1.5 to 2.0, which can ensure sufficient anti-demagnetization ability without making the ferrite too thick, which makes it difficult to weaken the magnetism. The further preferred range of W1 / W2 is 1.8 to 2.0, and the part of the permanent magnet in each pole that increases and decreases magnetization is as follows: Figure 6 shown.

[0044] In this embodiment, the first permanent magnet 7 is a rare earth permanent magnet, and the second permanent magnet 8 is a ferrite permanent magnet. The motor rotor of the present application has a higher power factor than the traditional motor that only uses ferrite permanent magnets by using a combination of rare earth permanent magnets and ferrite permanent magnets. When the first permanent magnet 7 is a rare earth permanent magnet, its main function is to provide a permanent magnetic field and enhance the no-load flux linkage. During magnetic weakening, the ferrite permanent magnet mainly acts on the armature. Due to the poor magnetic properties of ferrite, it is more easily weakened, so the magnetic weakening current is also smaller, and it is easier to increase the speed. At this time, the rare earth permanent magnet still maintains a relatively high permanent magnetic flux output. Based on this, the power factor of the motor is increased. In this embodiment, compared with the conventional structure, the motor power factor is increased from 0.85 to 0.88, the motor input current is reduced, and the system efficiency is improved.

[0045] In this embodiment, the magnetic channel occupancy rate δ satisfies 0.32≤δ≤0.38 or 0.54≤δ≤0.63.

[0046] The magnetic channel occupancy rate can be determined by the following formula:

[0047] δ=1-(w1+w3+w5) / (w1+w2+w3+w4+w5+2w6)

[0048] Where w1 is the thickness of the radially outermost flux barrier 2, w2 is the thickness of the magnetic channel 3 adjacent to the radially outermost flux barrier 2, and so on. w6 is the thickness of the core between the circumferential outer wall of the radially innermost flux barrier 2 under the same pole and the circumferential outer wall of the pole, as shown in Figure 6 shown.

[0049] When the magnetic channel occupancy rate is in the range of 0.32 to 0.38, the torque output is large. Since the flux barrier 2 is large, the motor leakage is small, and the Q-axis inductance is low, a large torque output is obtained at this time. When the magnetic channel occupancy rate is in the range of 0.54 to 0.63, although the flux barrier 2 is small, the D-axis magnetic channel width is large and the inductance is large, a large torque output is also obtained at this time, such as Figure 7 shown.

[0050] The permanent magnet pole arc coefficient in the mounting slot 4 is A0, where 0.35≤A0≤0.46. When the permanent magnet pole arc coefficient is within this range, the motor torque pulsation is low, such as Figure 8 As shown in FIG, within this range, its permanent magnet torque and reluctance torque can achieve peak-valley phase shift when synthesized.

[0051] Preferably, the pole arc coefficient of the permanent magnet in the mounting slot 4 is A0, the pole arc coefficient of the magnetic channel 3 adjacent to the radially outermost magnetic flux barrier 2 is A1, and the pole arc coefficient of the adjacent magnetic channel 3 located circumferentially outside the magnetic channel 3 is A2, where A2-A1>A1-A0.

[0052] Through the above design, the air gap magnetic field is still basically sinusoidally symmetrically distributed under armature reaction, which plays a positive role in suppressing motor torque pulsation and reducing losses. Figure 9 As shown in the figure, there is a comparison of the air gap magnetic density waveform under load of the present application and the conventional solution. It can be seen from the figure that after adopting the above-mentioned solution of the present application, the air gap magnetic density waveform under load is basically sinusoidal and symmetrically distributed, thereby reducing the motor torque pulsation and iron loss.

[0053] According to an embodiment of the present application, the reluctance motor includes a motor rotor and a motor stator, and the motor rotor is the above-mentioned motor rotor.

[0054] According to an embodiment of the present application, an electric vehicle includes the above-mentioned motor rotor or the above-mentioned reluctance motor.

[0055] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0056] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A motor rotor, characterized in that: The invention comprises a rotor core (1), wherein a plurality of magnetic barrier groups are arranged on the rotor core (1) along the circumferential direction, each magnetic barrier group comprises at least two magnetic flux barriers (2) arranged along the radial direction, a magnetic conductive channel (3) is formed between adjacent magnetic flux barriers (2), and in a cross section perpendicular to the central axis of the rotor core (1), the magnetic flux barriers (2) located at the radially outermost side under the same pole form a groove, and the rotor core (1) in the groove has a straight-line installation groove (4), and the installation groove (4) comprises a first groove portion (5) located at a first end and a second groove portion (6) located at a second end, the first groove portion (5) and the second groove portion (6) are connected, and the radial thickness of the first groove portion (5) and the second groove portion (6) are different.

2. The motor rotor according to claim 1, characterized in that: The first groove portion (5) and the second groove portion (6) have different lengths.

3. The motor rotor according to claim 1, characterized in that: The thickness of the first groove portion (5) is greater than the thickness of the second groove portion (6).

4. The motor rotor according to claim 2, characterized in that: The length of the first groove portion (5) is greater than the length of the second groove portion (6).

5. The motor rotor according to claim 3 or 4, characterized in that: A first permanent magnet (7) is arranged in the first groove portion (5), and a second permanent magnet (8) is arranged in the second groove portion (6); the coercive force of the first permanent magnet (7) is greater than the coercive force of the second permanent magnet (8).

6. The motor rotor according to claim 5, characterized in that: The first permanent magnet (7) is a rare earth permanent magnet, and the second permanent magnet (8) is a ferrite permanent magnet.

7. The motor rotor according to claim 6, characterized in that: The thickness of the first permanent magnet (7) is W1, and the thickness of the second permanent magnet (8) is W2, wherein W1 / W2=1.5-2.0; and / or the length of the first permanent magnet (7) is L1, and the length of the second permanent magnet (8) is L2, wherein L1 / L2=1.2-1.

8.

8. The motor rotor according to claim 1, characterized in that: The magnetic channel occupancy rate δ satisfies 0.32≤δ≤0.38 or 0.54≤δ≤0.

63.

9. The motor rotor according to claim 8, characterized in that: The magnetic channel occupancy rate is determined by the following formula: δ=1-(w1+w3+w5) / (w1+w2+w3+w4+w5+2w6) Wherein w1 is the thickness of the radially outermost magnetic flux barrier (2), w2 is the thickness of the magnetic conductive channel (3) adjacent to the radially outermost magnetic flux barrier (2), and so on, w6 is the thickness of the core between the circumferential outer wall of the radially innermost magnetic flux barrier (2) under the same pole and the circumferential outer wall of the pole.

10. The motor rotor according to claim 1, characterized in that: The permanent magnet pole arc coefficient in the installation slot (4) is A0, wherein 0.35≤A0≤0.46; and / or the permanent magnet pole arc coefficient in the installation slot (4) is A0, the magnetic conductive channel (3) adjacent to the radially outermost magnetic flux barrier (2) has a pole arc coefficient of A1, and the adjacent magnetic conductive channel (3) located circumferentially outside the magnetic conductive channel (3) has a pole arc coefficient of A2, wherein A2-A1>A1-A0.

11. A reluctance motor, comprising a motor rotor and a motor stator, characterized in that: The motor rotor is the motor rotor according to any one of claims 1 to 10.

12. An electric vehicle, characterized in that: The invention comprises the motor rotor as claimed in any one of claims 1 to 10 or the reluctance motor as claimed in claim 11.

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