High-magnetic-resistance low-magnetic-density rotor topology, motor and topology design method

Abstract

The application discloses a high-magnetic-resistance low-magnetic-density rotor topology, a motor and a topology design method, and relates to the technical field of automobile electrical engineering. The topology comprises a plurality of layers of grooves which are arranged on the outer side of a rotor. The arc-shaped grooves comprise air grooves and magnetic steel grooves. The air grooves are arranged on the outer side of the magnetic steel grooves, and the magnetic steel grooves are used for placing permanent magnets. The high-magnetic-resistance low-magnetic-density rotor topology, the motor and the topology design method can increase the proportion of the magnetic resistance torque, have the characteristics of low magnetic density, reduce the proportion of the permanent magnet torque under the same torque, and further reduce the amount of magnetic steel to achieve a low-cost design. Meanwhile, the magnetic field energy provided by a small amount of permanent magnets can improve high-speed power and reduce the attenuation of high-speed power.

Description

Technical Field

[0001] This invention relates to the field of automotive electrical engineering technology, and in particular to high reluctance, low magnetic flux density rotor topology, motor, and topology design method. Background Technology

[0002] In the automotive electric drive field, there are high requirements for motor cost while still meeting the overall vehicle's power performance requirements. This typically leads to a higher amount of magnets used, increasing costs. In some applications suitable for lower power levels, asynchronous motors are used, but their power decays quickly, resulting in insufficient performance. Balancing high performance and low cost in design often limits the design options for motor solutions. Summary of the Invention

[0003] The purpose of this invention is to provide a high reluctance, low magnetic flux density rotor topology, motor, and topology design method, which can increase the reluctance torque ratio, have low magnetic flux density characteristics, reduce the proportion of permanent magnet torque under the same torque, thereby reducing the amount of magnets used to achieve a low-cost design. At the same time, the magnetic field energy provided by a small amount of permanent magnets can improve high-speed power and reduce high-speed power attenuation.

[0004] This invention provides the following solution:

[0005] According to one aspect of the present invention, a high reluctance, low magnetic flux density rotor topology is provided, the high reluctance, low magnetic flux density rotor topology comprising:

[0006] Multi-layered slots formed on the outside of the rotor;

[0007] The multi-layered groove includes an air groove and a magnetic groove, which are symmetrically distributed along the center line.

[0008] The air trough is located outside the magnet trough, which is used to place permanent magnets.

[0009] Optionally, the number of air troughs is at least two layers, and the number of magnet troughs is at least one layer.

[0010] Optionally, the arc groove is an arc groove with an opening facing outwards, and the arc radius of the outer arc groove is smaller than the arc radius of the inner arc groove.

[0011] Optionally, the multi-layered slots are also equipped with magnetic bridges.

[0012] Optionally, the magnetic bridge includes a central magnetic bridge and an outer magnetic bridge.

[0013] Optionally, the magnetic bridge further includes: pairs of magnetic bridges symmetrically distributed along the centerline.

[0014] Optionally, the magnetic bridge located inside the rotor has a greater thickness and size than the magnetic bridge located outside the rotor.

[0015] Optionally, the quadrature-axis magnetic circuit can be specifically optimized by varying the width angles of multiple axes.

[0016] According to two aspects of the present invention, an electric motor is provided, the electric motor comprising a rotor employing the high reluctance and low magnetic flux density rotor topology described above.

[0017] According to three aspects of the present invention, a rotor topology design method is provided, applied to a high reluctance, low magnetic flux density rotor topology as described above, the rotor topology design method comprising:

[0018] Obtain the initial rotor topology;

[0019] The stress intensity of the initial rotor topology is checked;

[0020] Determine whether the safety factor for stress intensity verification is lower than the predetermined safety factor threshold;

[0021] If the safety factor for stress intensity verification is lower than the predetermined safety factor threshold, the size of the magnetic bridge will be increased.

[0022] Determine whether the safety factor after the magnetic bridge size reduction is lower than the predetermined safety factor threshold;

[0023] If the safety factor after reducing the size of the magnetic bridge is lower than the predetermined safety factor threshold, the number of magnetic bridges will be increased.

[0024] The above solution achieves the following beneficial technical effects:

[0025] To address the demand for low-cost, high-performance motors, this invention proposes a motor structure with a high reluctance torque ratio. This structure solves the problems of high cost due to the large amount of magnets used in permanent magnet synchronous motors and low cost but weak performance in asynchronous motors. It provides a suitable solution for some low-power motor applications or auxiliary drive applications. The rotor structure adopts a multi-layer magnetic circuit topology, combining multi-layer air magnetic barriers and permanent magnet magnetic circuits to increase the reluctance torque ratio and exhibit low magnetic flux density. This reduces the proportion of permanent magnet torque at the same torque, thereby reducing the amount of magnets used and achieving a low-cost design. At the same time, the magnetic field energy provided by the small amount of permanent magnets can improve high-speed power and reduce high-speed power attenuation. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a high reluctance, low magnetic flux density rotor topology provided in one or more embodiments of the present invention;

[0027] Figure 2 This is a schematic diagram of the magnetic bridge placement position in a high reluctance, low magnetic flux density rotor topology provided in one or more embodiments of the present invention;

[0028] Figure 3This is a schematic diagram of the air magnetic barrier layer design provided in one or more embodiments of the present invention;

[0029] Figure 4 This is a schematic diagram of the permanent magnet layer design provided in one or more embodiments of the present invention;

[0030] Figure 5 This is a structural diagram of a high reluctance, low magnetic flux density rotor topology provided in one or more embodiments of the present invention;

[0031] Figure 6 This is a structural diagram of a high reluctance, low magnetic flux density rotor topology provided in one or more embodiments of the present invention;

[0032] Figure 7 This is a flowchart of a rotor topology design method provided by one or more embodiments of the present invention;

[0033] Figure 8 This is a structural diagram of a rotor topology design device provided in one or more embodiments of the present invention. Detailed Implementation

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

[0035] Figure 1 This is a structural diagram of a high reluctance, low magnetic flux density rotor topology provided in one or more embodiments of the present invention. See also... Figure 1 The high reluctance, low magnetic flux density rotor topology includes: multiple slots. Furthermore, the multiple slots include: air slots 22, 23, and 24, and a magnet slot 25.

[0036] Among them, the magnetic steel groove 25 is used to place permanent magnets.

[0037] Typically, air slots 22, 23, and 24 are located outside the magnet slot 25. Unlike the magnet slot 25, air slots 22, 23, and 24 are not used to place permanent magnets, but rather to set magnetic resistance.

[0038] The purpose of setting up air slots 22, 23, and 24 is to effectively increase the proportion of reluctance torque in the total torque, thereby reducing the amount of magnets used in the motor and reducing costs.

[0039] In addition, the rotor reluctance flux path can be adjusted by changing the placement position of air slots 22, 23, and 24, as well as the changes in slot thickness and slot length.

[0040] The magnet slot 25 holds magnets to increase magnetic field energy and enhance the overall torque and power capacity of the motor.

[0041] The outermost edge of the rotor has a pair of tiny circular arcs Q, which are used to improve air gap magnetic field harmonics and reduce torque pulsation.

[0042] The core idea of ​​this embodiment is to achieve the goal of increasing the proportion of reluctance torque and reducing the proportion of permanent magnet torque under the same torque by cooperating with the magnet slot 25 and air slots 22, 23, 24 in the multi-layer slot. This reduces the amount of magnets used in the motor and thus reduces costs.

[0043] In addition, the magnetic field energy provided by only a small amount of permanent magnets can increase high-speed power and reduce the attenuation of high-speed power.

[0044] In the Figure 1 In the rotor topology shown, there are four layers of slots. The outer three layers are air slots 22, 23, and 24, which increase magnetic reluctance. The innermost layer is a magnet slot 25, used to house permanent magnets.

[0045] The multi-layered grooves have the following characteristics: the radii of the different arc-shaped grooves gradually increase from the outside to the inside. That is, the outermost arc-shaped groove has the smallest radius, while the innermost arc-shaped groove has the largest radius among all the arc-shaped grooves.

[0046] It is important to note that although the multi-layered slots share this general characteristic in appearance, this does not mean that the shape of the multi-layered slots is fixed and unadjustable. On the contrary, in the rotor topology provided in this embodiment, the shape parameters of the multi-layered slots are variable. Furthermore, by specifically designing the shape parameters of each layer in the multi-layered slots during the design phase, the rotor can have a reluctance flux path suitable for high-speed scenarios after being energized, making the rotor topology more adaptable to high-speed scenarios.

[0047] Outside the rotor topology described above is the motor stator 11. Inside the motor stator 11, stator coils 12 are also provided.

[0048] Furthermore, in order to make the rotor more suitable for high-speed scenarios, a magnetic bridge design has been added between the multi-layer slots.

[0049] Figure 2 The typical magnetic bridge placement location in a rotor topology is shown. See also Figure 2 The magnetic bridges added to the rotor topology include the central magnetic bridges b2, c2, and d2, and the external magnetic bridges a1, b1, c1, and d1.

[0050] The so-called central magnetic bridges b2, c2, and d2 are located between the two air slots or between the two magnetic slots. The so-called external magnetic bridges a1, b1, c1, and d1 are not located between the two arc-shaped slots, but are located outside the arc-shaped slots.

[0051] The main reason for adding the magnetic bridge design is to adapt to the high-speed operation of the motor.

[0052] Moreover, the more magnetic bridges there are and the thicker they are, the more significant the torque attenuation effect becomes.

[0053] Considering the more stringent stress requirements for rotor components located near the inner slots, the inner magnetic bridges c1 and d1 in the outer magnetic bridges need to be larger than the outer magnetic bridges b1 and a1. Similar requirements apply to the middle magnetic bridges; the inner magnetic bridges c2 and d2 are larger than the outer magnetic bridge b2. The thickness of the inner magnetic bridges d1, c1, c2, and d2 ranges from [1 to 1.5]. The thickness of the outer magnetic bridges b1, a1, and b2 ranges from [0.6 to 1]. Because the innermost magnetic slot requires more magnets than the three outer layers, a pair of magnetic bridges symmetrically distributed along the centerline are used to ensure mechanical strength.

[0054] If the required motor speed is low, the number and size of the magnetic bridges can be reduced according to the stress state. If the rotor strength is insufficient, the size of the magnetic bridges should be increased first, followed by the number of magnetic bridges, to reduce the impact on torque.

[0055] Figure 3 The spatial design of the air magnetic barrier layer in the rotor topology is shown. See also Figure 3 In this embodiment, the air magnetic barrier layer comprises three different levels. Each level has its own shape parameters.

[0056] Among the three air magnetic barrier layers, the outermost layer has the smallest width, L1. The middle layer has the next smallest width, L2. The innermost layer has the largest width, L3.

[0057] The curvature angles angle1, angle2, and angle3 of each of the three layers are also different.

[0058] In addition, the values ​​of the spatial interval parameters k1, k2, and k3 between the three layers are also different.

[0059] By optimizing the quadrature-axis magnetic circuit through different variations in multiple width angles, the difference between quadrature and direct-axis inductance is improved, the saliency ratio is optimized, and the generation of reluctance torque is enhanced.

[0060] Figure 4 The spatial design of a permanent magnet layer provided by one or more embodiments of the present invention is illustrated. See also Figure 4 The permanent magnet layer is located at the innermost side of the multi-layered groove.

[0061] Because the permanent magnet layer needs to spatially enclose other arc-shaped slots arranged sequentially on its outer side, its width needs to be greater than that of the air magnetic barrier layer on its outer side.

[0062] See Figure 4 In this embodiment, the permanent magnet layer is divided into three sections. Each section is set up separately and accommodates the magnets that need to be installed.

[0063] Using less permanent magnet material to enhance magnetic field energy, the three magnet slots are U-shaped. To balance the processing costs of different magnets and maximize the utilization of permanent magnet torque, the length and width of the magnets in each slot are equal, the magnets along the symmetrical extension direction of the U-shape are equal in size, and the magnets are symmetrically distributed along the d-axis. The length and thickness of the magnets in the middle and along the extension direction of the U-shape are different, i.e., L41≠L42, K44=K45. By varying the size of multiple magnets and the angle 4 of the magnet slots, a higher permanent magnet torque is provided.

[0064] The rotor magnetic circuit, composed of the three layers of air magnetic barriers and one layer of magnets, achieves the synergistic maximization of permanent magnet torque and reluctance torque output. It can provide high performance output with less magnets and slow down high-speed power decay.

[0065] It should be noted that the present invention is not limited to the combination of three layers of air magnetic barriers plus one layer of magnet. It can also be a combination of two layers of air magnetic barriers plus one layer of magnet, or two layers of air magnetic barriers plus two layers of magnet, etc., which will achieve the same effect.

[0066] Figure 5 and Figure 6 The different configurations of combining the aforementioned air magnetic barriers with magnets are shown respectively.

[0067] In the Figure 5 In the rotor topology shown, there are three layers of slots. The two outermost layers are air magnetic barrier layers, while the innermost layer is a magnet layer.

[0068] In the Figure 6 In the rotor topology shown, there are four layers of slots. In the configuration of four arc-shaped slots, the two outermost layers are air magnetic barrier layers, and the two innermost layers are magnet layers.

[0069] Figure 7 This is a flowchart of a rotor topology design method provided by one or more embodiments of the present invention. See also... Figure 7 The rotor topology design method includes the following steps:

[0070] S71, obtain the initial rotor topology.

[0071] S72, the stress intensity is checked for the initial rotor topology.

[0072] S73, determine whether the safety factor for stress intensity verification is lower than the predetermined safety factor threshold.

[0073] S74. If the safety factor for stress intensity verification is lower than the predetermined safety factor threshold, the size of the magnetic bridge shall be increased.

[0074] S75, determine whether the safety factor after the increase in the size of the magnetic bridge is lower than the predetermined safety factor threshold.

[0075] S76, if the safety factor after the magnetic bridge size reduction is lower than the predetermined safety factor threshold, the number of magnetic bridges is increased.

[0076] In addition to providing a high reluctance, low magnetic flux density rotor topology, this invention also provides a design method specifically for such a rotor topology. The design is performed according to the following process.

[0077] The first step in the design process is to initialize the rotor topology to be designed.

[0078] The above initialization process does not require consideration of the rotor's various design requirements. It only requires uniform initialization of all components and parameters in the rotor design process according to the usual conventions of rotor design.

[0079] After completing the above initialization operations, the stress intensity of the initialized rotor topology is checked.

[0080] After checking the stress intensity of the rotor topology, if the safety factor corresponding to the obtained rotor topology stress intensity is lower than the predetermined safety factor threshold, it indicates that the safety factor of the designed rotor topology does not meet the requirements. In this case, the magnetic bridge size recorded in the rotor topology should be increased.

[0081] If the safety factor still cannot meet the requirements after increasing the size, it is necessary to further increase the number of magnetic bridges.

[0082] After the above two reduction steps—that is, increasing the size and number of magnetic bridges—the rotor topology can meet the preset safety factor threshold. Conversely, if the safety factor is too redundant, the number and size can be reduced to further increase torque and reduce cost.

[0083] Figure 8 This is a structural diagram of a rotor topology design device provided in one or more embodiments of the present invention. See also Figure 8 The rotor topology design device includes:

[0084] The acquisition module 81 is used to acquire the initial rotor topology.

[0085] Verification module 82 is used to verify the stress intensity of the initial rotor topology.

[0086] The first judgment module 83 is used to determine whether the safety factor of the stress intensity check is lower than the predetermined safety factor threshold.

[0087] The first reduction module 84 is used to increase the size of the magnetic bridge if the safety factor of the stress intensity check is lower than a predetermined safety factor threshold.

[0088] The second judgment module 85 is used to determine whether the safety factor after the magnetic bridge size is increased is lower than the predetermined safety factor threshold.

[0089] The second reduction module 86 is used to increase the number of magnetic bridges if the safety factor after the magnetic bridge size reduction is lower than a predetermined safety factor threshold.

[0090] Furthermore, the present invention also provides an electric motor. This electric motor includes a high reluctance, low magnetic flux density rotor topology as described above.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rotor topology with high magnetic reluctance and low magnetic flux density, characterized in that, The high reluctance, low magnetic flux density rotor topology includes: Multi-layered slots formed on the outside of the rotor; The multi-layered groove includes an air groove and a magnetic groove, which are symmetrically distributed along the center line. The air trough is located outside the magnet trough, which is used to place permanent magnets.

2. The topology according to claim 1, characterized in that, The number of air troughs is at least two layers, and the number of magnetic steel troughs is at least one layer.

3. The topology according to claim 2, characterized in that, The arc groove is an arc groove with an opening facing outwards, and the arc radius of the outer arc groove is smaller than that of the inner arc groove.

4. The topology according to claim 1, characterized in that, The multi-layered groove is also equipped with a magnetic bridge.

5. The topology according to claim 4, characterized in that, The magnetic bridge includes a central magnetic bridge and an outer magnetic bridge.

6. The topology according to claim 5, characterized in that, The magnetic bridge also includes pairs of magnetic bridges symmetrically distributed along the center line.

7. The topology according to any one of claims 4 to 6, characterized in that, The magnetic bridge located inside the rotor has a greater thickness and size than the magnetic bridge located outside the rotor.

8. The topology according to claim 1, characterized in that, The quadrature magnetic circuit is specifically optimized by varying the width and angle of multiple widths.

9. An electric motor, characterized in that, The motor includes a rotor employing the high reluctance, low magnetic flux density rotor topology as described in any one of claims 1 to 8.

10. A topology design method, applied to the high reluctance, low magnetic flux density rotor topology according to any one of claims 1 to 8, characterized in that, The topology design method includes: Obtain the initial rotor topology; The stress intensity of the initial rotor topology is checked; Determine whether the safety factor for stress intensity verification is lower than the predetermined safety factor threshold; If the safety factor for stress intensity verification is lower than the predetermined safety factor threshold, the size of the magnetic bridge will be increased. Determine whether the safety factor after increasing the size of the magnetic bridge is lower than the predetermined safety factor threshold. If the safety factor after reducing the size of the magnetic bridge is lower than the predetermined safety factor threshold, the number of magnetic bridges will be increased.

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