permanent magnet motor

Abstract

The application provides a permanent magnet motor. The permanent magnet motor comprises a stator structure and a rotor structure, the stator structure is sleeved outside the rotor structure, and the rotor structure comprises: a first rotor core; a second rotor core, a plurality of mounting grooves are arranged at the second rotor core in a circumferential direction; a first permanent magnet, which is arranged in a circumferential direction of the second rotor core; and a second permanent magnet, which is mounted in the mounting groove. The two ends of the second rotor core are respectively provided with the first permanent magnet, and the side of the first permanent magnet, which is away from the second rotor core, is provided with the first rotor core. The stator structure comprises a stator core. The total height of the rotor structure in the axial direction of the permanent magnet motor is z, the height of the stator core in the axial direction of the permanent magnet motor is y, and z / y<=4. According to the permanent magnet motor, the matching relationship between the stator structure and the rotor structure can be optimized, the utilization rate of the stator core and the stator magnetic field can be improved, the cost of the permanent magnet motor can be reduced, the volume of the core loss generated by the stator part can be reduced, and the iron loss can be reduced.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor technology, and more specifically, to a permanent magnet motor. Background Technology

[0002] With the improvement of energy efficiency standards for permanent magnet motors, higher requirements have been placed on the energy efficiency level of permanent magnet motors. For permanent magnet motors, it is necessary to further improve their efficiency and torque density.

[0003] In existing permanent magnet motors, when the magnets are magnetized tangentially or radially, a large amount of leakage flux is generated at both ends of the permanent magnet motor, resulting in poor utilization efficiency of the permanent magnet and affecting the working performance of the permanent magnet motor.

[0004] To address this issue, a new type of permanent magnet motor has emerged in the prior art. This motor reduces magnetic leakage at both ends by adding axial magnets, thereby improving the utilization efficiency of the permanent magnets. Adding axial magnets also reduces magnetic leakage from tangential magnets. When designing the stator and rotor structures of this type of permanent magnet motor, the matching relationship between the stator core and rotor structure must be considered. An improper matching relationship will lead to low utilization of the stator core and stator magnetic field, increased cost of the permanent magnet motor, and increased volume of the stator section responsible for core losses, resulting in increased iron losses. Summary of the Invention

[0005] The main objective of this invention is to provide a permanent magnet motor that optimizes the matching relationship between the stator and rotor structures, improves the utilization rate of the stator core and stator magnetic field, reduces the cost of the permanent magnet motor, reduces the volume of the stator section that causes core loss, and reduces iron loss.

[0006] To achieve the above objectives, according to one aspect of the present invention, a permanent magnet motor is provided, comprising a stator structure and a rotor structure, wherein the stator structure is sleeved outside the rotor structure, and the rotor structure includes:

[0007] First rotor core;

[0008] The second rotor core has multiple mounting slots spaced apart along the circumference.

[0009] The first permanent magnet is axially magnetized, and multiple first permanent magnets are arranged circumferentially along the second rotor core.

[0010] The second permanent magnet is tangentially magnetized and installed in the mounting slot;

[0011] The first permanent magnet is provided at both ends of the second rotor core, and the first rotor core is provided on the side of the first permanent magnet away from the second rotor core.

[0012] The stator structure includes the stator core;

[0013] The total height of the rotor structure along the axis of the permanent magnet motor is z, and the height of the stator core along the axis of the permanent magnet motor is y, z / y≤4.

[0014] Furthermore, 1.0 ≤ z / y ≤ 3.0.

[0015] Furthermore, the outer diameter of the first permanent magnet located at at least one end of the second rotor core is smaller than the inner diameter of the stator core.

[0016] Furthermore, the outer diameter of the first permanent magnet located at at least one end of the second rotor core is smaller than the maximum diameter of the outer diameters of the first rotor core and the second rotor core.

[0017] Furthermore, the stator structure includes a stator core, a second rotor core with a height of x along the axis of the permanent magnet motor, and a stator core with a height of y along the axis of the permanent magnet motor, where x / y≤2.

[0018] Furthermore, 0.5 ≤ x / y ≤ 1.5.

[0019] Furthermore, 0.5 ≤ x / y ≤ 0.98.

[0020] Furthermore, the height of the second rotor core along the axis of the permanent magnet motor is x, the height of the stator core along the axis of the permanent magnet motor is y, and the height of the first permanent magnet along the axis of the permanent magnet motor is b, where 0.01x≤b≤0.7x; and / or, 0.015y≤b≤0.9y.

[0021] Furthermore, an air gap is formed between the stator structure and the rotor structure, and the difference between the maximum outer diameter of the second rotor core and the maximum outer diameter of the first permanent magnet in the rotor structure is w, where w≥0.

[0022] Furthermore, the thickness of the air gap is δ, 0.5*min(δ)≤w≤14*min(δ).

[0023] Furthermore, a projection is made onto the end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the area of ​​one pole of the first permanent magnet is s1, and the axial height of the second rotor core along its own central axis is x. s1 is inversely proportional to x.

[0024] Furthermore, s1 = -B*x + D, where the value of B ranges from 25 to 100, and the value of D ranges from 400 to 1600.

[0025] Furthermore, a projection is made on one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the area of ​​one pole of the first permanent magnet is s1, and the area of ​​one pole of the second rotor core is s2, where s1 / s2≥1.

[0026] Furthermore, 1.05 ≤ s1 / s2 ≤ 1.95.

[0027] Furthermore, a projection is made onto one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the area of ​​one pole of the first permanent magnet is s1, and the area of ​​one pole of the second permanent magnet is s3. In the cross section passing through the central axis of the second rotor core, the area of ​​one pole of the first permanent magnet is s4, and the area of ​​one pole of the second permanent magnet is s5, where 0.8*s3≤s1≤2.4*s5, and / or 0.3*s3≤s4≤0.8*s5.

[0028] Furthermore, a projection is made on one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the angle between the two endpoints of one pole of the first permanent magnet near the outer circle of the rotor and the center of the second rotor core is α, and the angle between the two endpoints of the magnetically conductive part of one pole of the second rotor core near the outer circle of the rotor and the center of the second rotor core is β, where α / β≥1.

[0029] Furthermore, 1 ≤ α / β ≤ 1.62.

[0030] Furthermore, a magnetic shielding groove is provided on the side of the mounting groove near the central axis of the second rotor core; a projection is made on one end face of the second rotor core along the axial direction of the second rotor core, and in this projection plane, the projection of the first permanent magnet is configured to partially cover the projection of the magnetic shielding groove.

[0031] Furthermore, the area of ​​the projection of the first permanent magnet covering the projection of the magnetic isolation groove is less than or equal to 75% of the projected area of ​​the magnetic isolation groove.

[0032] Furthermore, the area of ​​the projection of the first permanent magnet covering the projection of the magnetic isolation groove is less than or equal to 25% of the projected area of ​​the magnetic isolation groove.

[0033] Furthermore, a projection is made onto one end face of the second rotor core along the axial direction of the second rotor core. Within this projection plane, the area of ​​one pole of the first permanent magnet is s1, and the thickness of the first permanent magnet along the axial direction of the second rotor core is b. s1 and b are inversely proportional.

[0034] Furthermore, the relationship between s1 and b satisfies the dimensionless formula s1=-A*b+C, where the value of A ranges from 5 to 20, and the value of C ranges from 120 to 400.

[0035] Furthermore, a projection is made on one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the area of ​​one pole of the first permanent magnet is s1, the area of ​​one pole of the second rotor core is s2, and the area of ​​one pole of the second permanent magnet is s3, where 0.2≤s2 / (s1+s3)≤1.

[0036] Furthermore, 0.3≤s2 / (s1+s3)≤0.6.

[0037] Furthermore, a projection is made on one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the length of the line connecting the central axis of the second rotor core and the center of the end edge of one pole of the first permanent magnet near the outer circle of the rotor is i. The maximum value of the line connecting the central axis of the second rotor core and each point on the outer circle of the second rotor core is max(j), where max(i)≤max(j).

[0038] Furthermore, the length of the line connecting the central axis of the second rotor core and the center of the end edge of one pole of the second permanent magnet near the outer circle of the rotor is ii, max(j)≥max(i)≥0.8*ii.

[0039] Furthermore, max(j) ≥ max(i) ≥ 0.95*ii.

[0040] Furthermore, a projection is made on one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the minimum value of the radial width e of the first permanent magnet is min(e), and the maximum value of the radial width g of the second permanent magnet is max(g), where 0.5≤min(e) / max(g)≤2.

[0041] Furthermore, 0.6 ≤ min(e) / max(g) ≤ 1.6.

[0042] Furthermore, a projection is made onto one end face of the second rotor core along the axial direction of the second rotor core. In this projection plane, the sum of the angles formed by the lines connecting the two endpoints of each pole of the first permanent magnet near the outer circle of the rotor and the center of the second rotor core is α*2q. The ratio of this sum of angles to the circumferential angle of the second rotor core is a, where a = α*2q / 360. The thickness of the first permanent magnet along the axial direction of the second rotor core is b, where 2 ≤ b / a ≤ 6, and q is the number of pole pairs of the first permanent magnet.

[0043] According to the technical solution of this invention, a permanent magnet motor includes a stator structure and a rotor structure. The stator structure is fitted outside the rotor structure. The rotor structure includes: a first rotor core; a second rotor core, the second rotor core having multiple mounting slots spaced apart circumferentially; a first permanent magnet, axially magnetized, with multiple first permanent magnets arranged circumferentially along the second rotor core; a second permanent magnet, installed within the mounting slots; first permanent magnets are respectively provided at both ends of the second rotor core, with the first rotor core located on the side of the first permanent magnet furthest from the second rotor core; the stator structure includes a stator core; the total height of the rotor structure along the axial direction of the permanent magnet motor is z, and the height of the stator core along the axial direction of the permanent magnet motor is y, where z / y≤4. By limiting the height ratio of the stator core and the rotor structure, the utilization rate of the stator core and the stator magnetic field can be improved, reducing the cost of the permanent magnet motor; simultaneously, the volume of the stator section that generates core losses can be reduced, thus reducing iron loss. Attached Figure Description

[0044] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0045] Figure 1 A perspective structural diagram of the rotor structure according to an embodiment of the present invention is shown;

[0046] Figure 2 An exploded structural diagram of the rotor structure according to an embodiment of the present invention is shown;

[0047] Figure 3 A cross-sectional view of the rotor structure according to an embodiment of the present invention is shown;

[0048] Figure 4 A structural layout diagram of the rotor structure according to an embodiment of the present invention is shown;

[0049] Figure 5 A cross-sectional structural diagram of the rotor structure according to an embodiment of the present invention is shown;

[0050] Figure 6 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0051] Figure 7 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0052] Figure 8 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0053] Figure 9 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0054] Figure 10 A perspective structural diagram of a permanent magnet motor structure according to an embodiment of the present invention is shown;

[0055] Figure 11 A diagram showing the relationship between the polarity arrangement of the rotor structure and the unloaded magnetic flux in an embodiment of the present invention is shown.

[0056] Figure 12 This diagram illustrates the relationship between the angular deviation of the geometric center line and the magnetic field center line of the first permanent magnet in the rotor structure of an embodiment of the present invention and the unloaded magnetic flux linkage.

[0057] Figure 13 The graph showing the relationship between α / β and permanent magnet utilization rate in the rotor structure of an embodiment of the present invention is illustrated.

[0058] Figure 14 The diagram shows the relationship between α / γ and permanent magnet utilization and leakage coefficient in the rotor structure of an embodiment of the present invention.

[0059] Figure 15 The diagram shows the relationship between 360 / 2p / α and space utilization and saturation coefficient in the rotor structure of an embodiment of the present invention.

[0060] Figure 16 The diagram shows the relationship between b / a and the utilization rate and demagnetization rate of the permanent magnet in the rotor structure of an embodiment of the present invention.

[0061] Figure 17 A graph showing the relationship between s1 / s2 and permanent magnet utilization rate in the rotor structure of an embodiment of the present invention is shown.

[0062] Figure 18 The diagram showing the relationship between b / m and the demagnetization rate of the permanent magnet in the rotor structure of an embodiment of the present invention is illustrated.

[0063] Figure 19 The graph shows the relationship between c / m, no-load flux linkage utilization, and iron loss in the rotor structure of an embodiment of the present invention.

[0064] Figure 20 A comparison diagram of the leakage flux coefficients of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0065] Figure 21 A comparison diagram of the air gap magnetic flux density waveforms of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0066] Figure 22 A comparison diagram of the air gap magnetic flux density amplitude of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown;

[0067] Figure 23A comparison diagram of the no-load magnetic flux of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0068] Figure 24 A comparison diagram of the output torque-current curves of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0069] Figure 25 A graph comparing the output torque of a permanent magnet motor according to an embodiment of the present invention with that of a prior art permanent magnet motor under the same current is shown.

[0070] Figure 26 A comparison graph of efficiency curves of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0071] Figure 27 A comparison diagram of copper loss curves of a permanent magnet motor according to an embodiment of the present invention and a permanent magnet motor of the prior art is shown.

[0072] Figure 28 A graph comparing the iron losses of a permanent magnet motor according to an embodiment of the present invention with those of a permanent magnet motor in the prior art is shown.

[0073] Figure 29 The diagram showing the relationship between s1 / s3 and the unloaded flux linkage in the rotor structure of an embodiment of the present invention is illustrated.

[0074] Figure 30 The diagram shows the relationship between s1 / s5 and the no-load flux linkage utilization rate in the rotor structure of an embodiment of the present invention.

[0075] Figure 31 The diagram showing the relationship between s4 / s3 and the demagnetization rate of the permanent magnet in the rotor structure of an embodiment of the present invention is illustrated.

[0076] Figure 32 The diagram showing the relationship between s4 / s5 and the saturation coefficient of the permanent magnet motor in the rotor structure of an embodiment of the present invention is illustrated.

[0077] Figure 33 The graph showing the relationship between s1 / max(j) and the magnetic focusing effect coefficient in the rotor structure of an embodiment of the present invention is illustrated.

[0078] Figure 34 The diagram shows the relationship between s2 / (s1+s3) and rotor core utilization and iron loss in the rotor structure of an embodiment of the present invention.

[0079] Figure 35 The graph shows the relationship between s1 and iron loss and copper loss in the rotor structure of an embodiment of the present invention.

[0080] Figure 36The graph shows the relationship between a*b and air gap magnetic flux density and utilization rate of the first permanent magnet in the rotor structure of an embodiment of the present invention.

[0081] Figure 37 The graph shows the relationship between c / b and saturation coefficient and rotor core utilization rate in the rotor structure of an embodiment of the present invention.

[0082] Figure 38 A schematic diagram of the rotor structure according to an embodiment of the present invention is shown;

[0083] Figure 39 A schematic diagram of the structure of the first permanent magnet in the rotor structure of an embodiment of the present invention is shown;

[0084] Figure 40 A schematic diagram of the structure of the second rotor core of an embodiment of the present invention is shown;

[0085] Figure 41 A schematic diagram of the structure of a motor according to an embodiment of the present invention is shown;

[0086] Figure 42 A graph showing the relationship between the coverage area ratio of the first permanent magnet and the magnetic isolation groove of the rotor structure according to an embodiment of the present invention and the utilization rate of the unloaded magnetic flux and the permanent magnet is illustrated.

[0087] Figure 43 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0088] Figure 44 The diagram shows the relationship between max(i) / ii and the leakage flux coefficient at the top of the second permanent magnet in the rotor structure of an embodiment of the present invention.

[0089] Figure 45 The diagram shows the relationship between d / f, the leakage flux coefficient at the bottom of the second permanent magnet, and the utilization rate of the first permanent magnet in the rotor structure of an embodiment of the present invention.

[0090] Figure 46 A dimensional structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0091] Figure 47 The diagram showing the relationship between min(h) / max(i) and unloaded flux linkage in the rotor structure of an embodiment of the present invention is illustrated.

[0092] Figure 48 The diagram showing the relationship between max(k) / d and unloaded flux linkage in the rotor structure of an embodiment of the present invention is illustrated.

[0093] Figure 49 The graph showing the relationship between min(e) / max(g) and leakage flux coefficient in the rotor structure of an embodiment of the present invention is illustrated.

[0094] Figure 50 The diagram shows the relationship between max(e) / min(o) and max(e) / max(o) and the saturation coefficient of the second rotor core in the rotor structure of an embodiment of the present invention.

[0095] Figure 51 A graph showing the relationship between min(l) / max(e) and the saturation coefficient of the first rotor core in the rotor structure of an embodiment of the present invention is shown.

[0096] Figure 52 The graph shows the relationship between x / y and the utilization rate of the second rotor core and the utilization rate of the stator magnetic field in the rotor structure of an embodiment of the present invention.

[0097] Figure 53 The diagram shows the relationship between s1 and iron loss and copper loss in a rotor structure under a certain x-axis according to an embodiment of the present invention.

[0098] Figure 54 The diagram showing the relationship between z / y and stator core utilization rate in the rotor structure of an embodiment of the present invention is illustrated.

[0099] Figure 55 A graph showing the relationship between b / x, b / y and the saturation coefficient of the second rotor core in the rotor structure of an embodiment of the present invention is shown; and

[0100] Figure 56 It shows Figure 38 A schematic diagram of the AA-direction cross-section structure.

[0101] The above figures include the following reference numerals:

[0102] 1. First rotor core; 2. Second rotor core; 3. First permanent magnet; 4. Second permanent magnet; 5. First polarity; 6. Second polarity; 7. Third polarity; 8. Fourth polarity; 11. Magnetic isolation slot; 12. Stator core. Detailed Implementation

[0103] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0104] See also Figures 1 to 56 As shown, according to an embodiment of the present invention, the permanent magnet motor includes a rotor structure and a stator structure, which is disposed radially outside the rotor structure.

[0105] The rotor structure includes: a first rotor core 1; a second rotor core 2, the second rotor core 2 having multiple mounting slots spaced apart along the circumference; a first permanent magnet 3, axially magnetized, the first permanent magnet 3 including a first polarity 5 and a second polarity 6; a second permanent magnet 4, including a third polarity 7 and a fourth polarity 8, the second permanent magnet 4 being installed in the mounting slots; the first permanent magnet 3 is respectively provided at both ends of the second rotor core 2, and the first rotor core 1 is provided on the side of the first permanent magnet 3 away from the second rotor core 2.

[0106] In one embodiment, the stator structure includes a stator core 12, and the outer diameter of the first permanent magnet 3 located at at least one end of the second rotor core 2 is smaller than the inner diameter of the stator core 12.

[0107] Preferably, the outer diameter of the first permanent magnet 3 located at at least one end of the second rotor core 2 is smaller than the maximum diameter of the outer diameters of the first rotor core 1 and the second rotor core 2.

[0108] This arrangement allows as many of the first permanent magnets 3 as possible to come into contact with the second rotor core 2, thereby improving the utilization rate of the first permanent magnets 3.

[0109] In one embodiment, the stator structure is sleeved on the outer periphery of the rotor structure and forms an air gap between them. The difference between the maximum outer diameter of the second rotor core 2 and the maximum outer diameter of the first permanent magnet 3 is w, where w ≥ 0.

[0110] In one embodiment, the thickness of the air gap is δ, where 0.5*min(δ)≤w≤14*min(δ). This limitation ensures that the air gap is saturated, allowing the magnetic lines of force generated by the permanent magnet to enter the air gap as effective magnetic lines of force, thereby increasing the output torque of the permanent magnet motor.

[0111] In one embodiment, the stator structure includes a stator core 12, which is sleeved on the outside of the second rotor core 2 of the rotor structure.

[0112] In one embodiment, the height of the second rotor core 2 along the axial direction of the permanent magnet motor is x, and the height of the stator core 12 along the axial direction of the permanent magnet motor is y, where x / y≤2.

[0113] In one embodiment, 0.5 ≤ x / y ≤ 1.5.

[0114] In one embodiment, 0.5 ≤ x / y ≤ 0.98.

[0115] like Figure 10 As shown, in one embodiment, the height x of the second rotor core 2 along the axial direction of the permanent magnet motor is less than the height y of the stator core 12 along the axial direction of the permanent magnet motor.

[0116] Figure 41In the equation, x represents the axial length of the second rotor core 2, y represents the axial length of the stator core 12, and z represents the axial length of the entire permanent magnet motor rotor structure.

[0117] By limiting the height ratio of the second rotor core 2 and the stator core 12, the utilization rate of the second rotor core 2 and the stator magnetic field can be improved, reducing the cost of the permanent magnet motor; at the same time, the core loss of the stator core 12 can be reduced, improving the efficiency of the permanent magnet motor. Figure 52 The curves showing the utilization rates of the second rotor core and the stator magnetic field as a function of x / y are presented. When x / y is greater than 1.5, the rate of decrease in the utilization rate of the second rotor core begins to increase; when x / y is less than 0.5, the rate of decrease in the utilization rate of the stator magnetic field increases. When x / y is greater than 2, because the second rotor core 2 is much higher than the stator core 12, some rotor magnetic lines cannot enter the stator, resulting in a sharp decrease in the utilization rate of the rotor core.

[0118] In one embodiment, the total height of the rotor structure along the axial direction of the permanent magnet motor is z, and the height of the stator core 12 along the axial direction of the permanent magnet motor is y, where z / y≤4.

[0119] In one embodiment, 1.0 ≤ z / y ≤ 3.0.

[0120] By limiting the height ratio of the stator core 12 to the rotor structure, the utilization rate of the stator core 12 can be improved, and the cost of the permanent magnet motor can be reduced; at the same time, the volume of the stator section that causes core losses can be reduced, thus reducing iron losses. Figure 54 The figure shows the relationship between stator core utilization and z / y. As z / y increases, stator core utilization first increases and then decreases. When z / y is greater than 4, the stator core utilization decreases more significantly because the rotor and stator core stacking height ratio exceeds the optimal ratio by too much. When z / y is in the range of 1 to 3, the stator core utilization is relatively high.

[0121] In one embodiment, the height of the second rotor core 2 along the axial direction of the permanent magnet motor is x, the height of the stator core 12 along the axial direction of the permanent magnet motor is y, and the height of the first permanent magnet 3 along the axial direction of the permanent magnet motor is b, where 0.01x ≤ b ≤ 0.7x; and / or, 0.015y ≤ b ≤ 0.9y.

[0122] By limiting the relationship between the thickness of the first permanent magnet 3 and the height of the stator core 12 / rotor core, the saturation of the stator and rotor cores caused by the magnetic lines of force of the first permanent magnet 3 can be reduced, thereby reducing the core loss of the permanent magnet motor. Figure 55The figure shows the curves of the saturation coefficient of the permanent magnet motor as a function of b / x and b / y. As b / x and b / y increase, the saturation coefficient of the permanent magnet motor increases. When b / x is less than 0.01 or b / y is less than 0.015, the saturation coefficient of the permanent magnet motor is too low, which will affect the output of the permanent magnet motor. When b / x is greater than 0.7 or b / y is greater than 0.9, the saturation caused by the magnetic field lines of the first permanent magnet increases, and the saturation coefficient of the permanent magnet motor increases sharply.

[0123] In one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the polarity arrangement of the first permanent magnet 3 and the second permanent magnet 4 in the counterclockwise direction is first polarity 5, third polarity 7, second polarity 6, and fourth polarity 8, wherein the first polarity 5 and the third polarity 7 are the same, and the second polarity 6 and the fourth polarity 8 are the same.

[0124] The aforementioned projection plane is perpendicular to the central axis of the second rotor core 2. The first rotor core 1, the second rotor core 2, the first permanent magnet 3, and the second permanent magnet 4 are all projected onto this projection plane, thereby unifying these structures in one plane, which facilitates the description of the structure and the definition of the dimensional relationships.

[0125] The rotor structure simultaneously incorporates a first permanent magnet 3 and a second permanent magnet 4, which together provide magnetic field lines for the permanent magnet motor, thereby increasing the output power of the permanent magnet motor.

[0126] The rotor structure arranges the first permanent magnet 3 and the second permanent magnet 4 in a counterclockwise polarity order as first polarity 5, third polarity 7, second polarity 6, and fourth polarity 8, where first polarity 5 and third polarity 7 are the same, and second polarity 6 and fourth polarity 8 are the same. The magnetic lines of force of the first permanent magnet 3 with first polarity 5 and second polarity 6 enter the second rotor core 2 axially, while the magnetic lines of force of the second permanent magnet 4 with third polarity 7 and fourth polarity 8 enter the second rotor core 2 tangentially or radially. The two sets of magnetic lines of force are mutually squeezed on the second rotor core 2, so that both sets of magnetic lines of force can and can only enter the air gap, increasing the magnetic flux density of the air gap. This effectively reduces the leakage flux at both ends of the second permanent magnet, thereby increasing the no-load flux linkage. This can effectively improve the efficiency and torque density of the permanent magnet motor and increase the output of the permanent magnet motor.

[0127] In one embodiment, the polarity arrangement of permanent magnets in the rotor structure is explained using the tangential magnetization of the second permanent magnet 4 as an example.

[0128] In the above embodiments, the polarity of the first permanent magnet 3 refers to the polarity of the end of the first permanent magnet 3 facing the second rotor core 2, wherein the polarities of the first polarity 5 and the second polarity 6 are opposite. For example, when the first polarity 5 is the N pole, then the second polarity 6 is the S pole. The polarity of the second permanent magnet 4 refers to the polarity of the side of the second permanent magnet 4 facing the second rotor core 2. The polarity of the second permanent magnet 4 is distributed such that the third polarity 7 of the second permanent magnet 4 faces the first polarity 5 of the first permanent magnet 3. The polarity of the second rotor core 2 corresponding to the polarity of the second permanent magnet 4 is the same as the polarity of the second rotor core 2 corresponding to the polarity of the second permanent magnet 3. The third polarity 7 of the second permanent magnet 4 is the same as the first polarity 5 of the first permanent magnet 3. When the first polarity 5 is the N pole, then the third polarity 7 is also the N pole. The fourth polarity 8 of the second permanent magnet 4 is the same as the second polarity 6 of the first permanent magnet 3. When the second polarity 6 is the S pole, then the fourth polarity 8 is also the S pole.

[0129] See also Figure 4 and 11 The diagram shows the no-load flux linkage of a permanent magnet motor when using different polarity combinations. With the first polarity 5 designated as 1, the second polarity 6 as 2, the third polarity 7 as 3, and the fourth polarity 8 as 4, there are eight possible combinations: 1324, 2314, 1314, 2324, 1423, 2413, 1413, and 2423. The no-load flux linkage is largest in the order 1324 and 2413, and smallest in the order 2314 and 1423.

[0130] like Figure 11 As shown, the polarity arrangement of the rotor structure is set counterclockwise in the order of first polarity 5, third polarity 7, second polarity 6, and fourth polarity 8, forming a 1324 or 2413 combination. In this case, the magnetic lines of force on both ends of the second rotor core 2 exhibit a squeezing effect, and the unloaded flux linkage is the largest. If the axial relativity of the first polarity 5 and the second polarity 6 is not considered, and the polarity sequence is first polarity 5, third polarity 7, first polarity 5, fourth polarity 8 or second polarity 6, third polarity 7, second polarity 6, fourth polarity 8, then the magnetic lines of force on one end of the second rotor core 2 exhibit a squeezing effect, and the magnetic lines of force on the other end exhibit a diverging effect, reducing the unloaded flux linkage by 32.8%. If the polarity sequence is second polarity 6, third polarity 7, first polarity 5, and fourth polarity 8, then the magnetic lines of force on both ends of the second rotor core 2 exhibit a diverging effect, and the unloaded flux linkage is significantly reduced by 65.2%.

[0131] In one embodiment, the first permanent magnet 3 is divided into multiple magnetization zones along the circumference. The magnetization directions of two adjacent magnetization zones are opposite. The magnetization zone is projected onto one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the circumferential sides of each magnetization zone partially overlap with two adjacent second permanent magnets 4. The magnetization directions of the two adjacent second permanent magnets 4 are opposite. Each magnetization zone and the two adjacent second permanent magnets 4 form a magnetic field region. The polarity of the magnetization zone facing the magnetic field region is the same as the polarity of the two adjacent second permanent magnets 4 facing the magnetic field region.

[0132] In this embodiment, among the multiple magnetization zones of the first permanent magnets 3 located at both ends of the second rotor core 2, the two magnetization zones corresponding to the same magnetic field region have the same polarity towards the magnetic field region. The two second permanent magnets 4 on both sides of the circumferential side of the magnetic field region have the same polarity towards the magnetic field region, and the same polarity as the magnetization zones towards the magnetic field region. This allows the magnetic lines of force at both ends to be squeezed towards the magnetic field region in the middle. Therefore, the squeezing effect of the magnetic lines of force in the magnetic field region can be made more significant, maximizing the unloaded magnetic flux, effectively enhancing the magnetic field strength of the permanent magnet motor, and increasing the output of the permanent magnet motor.

[0133] In one embodiment, the second permanent magnet 4 is in a straight line shape and is arranged radially along the second rotor core 2. The straight line shape of the second permanent magnet 4, arranged radially along the second rotor core 2, divides the second rotor core 2 circumferentially into multiple sector-shaped regions. This makes the shape of the magnetic field region formed by the second rotor core 2 more closely match the shape of each magnetized region of the first permanent magnet 3. Furthermore, the second permanent magnet 4 forms two sidewalls of the magnetic field region, thus improving the structural compatibility between the magnetic field region and each permanent magnet. This also allows for a more rational planning of the distribution and orientation of magnetic lines of force, enabling more efficient use of the magnetic lines of force to form a magnetic field, resulting in higher magnetic field strength and a more powerful permanent magnet motor.

[0134] The second permanent magnet 4 can also adopt other structural forms, such as V-shape, etc.

[0135] In one embodiment, a magnetized region of the first permanent magnet 3 covers the same polarity region of an adjacent second permanent magnet 4 on a first side in the circumferential direction, and the magnetized region covers the same polarity region of an adjacent second permanent magnet 4 on a second side in the circumferential direction.

[0136] In one embodiment, the magnetized regions of the first permanent magnet 3 can be spaced apart, meaning that the magnetized regions of the first permanent magnet 3 are not adjacent and have non-magnetized regions in between. By setting non-magnetized regions between adjacent magnetized regions, the ratio of magnetized to non-magnetized regions of the first permanent magnet can be adjusted by regulating the area of ​​the non-magnetized regions. This reduces the saturation level of the permanent magnet motor, improves the utilization rate of the no-load flux linkage of the permanent magnet motor, helps reduce losses, reduces the difficulty of magnetizing the first permanent magnet, and lowers the cost of the permanent magnet.

[0137] See also Figure 5 As shown, in one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2, and the geometric center line of at least one pair of poles of the first permanent magnet 3 deviates from the rotor magnetic field center line of the corresponding second rotor core 2 by less than or equal to 5°.

[0138] Preferably, the geometric center line of at least one pair of poles of the first permanent magnet 3 coincides with the rotor magnetic field center line of the corresponding second rotor core 2. Defining the geometric position of at least some poles of the first permanent magnet 3 can reduce magnetic leakage caused by the rotor magnetic field diverging towards the rotor end face. In this embodiment, the geometric center line of a magnetized region of the first permanent magnet 3 is the center line of the two boundary lines of the magnetized region.

[0139] The center of the magnetic field generated by the second permanent magnet 4 in the second rotor core 2 is the center of the rotor magnetic field, which is the position with the strongest magnetic field in the second rotor core 2; the center of the magnetic field of the magnetized area of ​​the first permanent magnet 3 is the geometric center of the magnetized area of ​​the first permanent magnet 3. If the angular deviation between the center lines of the two magnetic fields is too large, the mutual squeezing effect of the two sets of magnetic lines will be weakened, and the magnetic field of the second permanent magnet 4 will diverge at the end with the first permanent magnet 3 as the path, resulting in increased magnetic leakage; when the center lines of the two magnetic fields are aligned, the squeezing effect of the two sets of magnetic lines is optimal and the magnetic leakage is minimal.

[0140] Experiments have verified that when the angular deviation between the geometric center line of a magnetized region of the first permanent magnet 3 and the corresponding rotor magnetic field center line is 5°, its unloaded flux linkage decreases by 10% compared to when the angle is 0°, the current increases by 10.5%, and the copper loss increases by 21%. If this angular deviation increases further, it will cause a further increase in current and copper loss. Figure 12 The figure shows the curve of the unloaded flux linkage changing with the angular deviation between the two. When the angular deviation between the two is greater than 5°, the descent speed of the unloaded flux linkage becomes faster, which means that the leakage flux increases further.

[0141] See also Figure 6As shown, in one embodiment, a projection is made on the end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the angle between the two endpoints of one pole of the first permanent magnet 3 near the outer circle of the rotor and the center of the second rotor core 2 is α, and the angle between the two endpoints of the magnetically conductive portion of one pole of the second rotor core 2 near the outer circle of the rotor and the center of the second rotor core 2 is β, where α / β≥1, preferably, 1<α / β≤1.62.

[0142] The magnetic lines of force of the first permanent magnet 3 flow into the air gap through the second rotor core 2 to interact with the stator magnetic field and generate torque. This limits the relationship between α and β, which can reduce the end leakage magnetic field of the second permanent magnet 4 and improve the utilization rate of the first permanent magnet 3 and the second permanent magnet 4.

[0143] Specifically, the magnetically conductive portion of the second rotor core 2 is the direct path for the magnetic flux lines of the first permanent magnet 3. If α / β is too large, a significant portion of the first permanent magnet 3 will not be able to directly contact the second rotor core 2, resulting in no flow path for its magnetic flux lines. This portion of the first permanent magnet 3 without a flow path does not contribute to the air gap magnetic flux density, leading to low utilization of the first permanent magnet 3. If α / β is too small, the coverage area of ​​the first permanent magnet 3 on the end face of the second rotor core 2 will be small, resulting in a large area of ​​the second permanent magnet 4 not being covered by the first permanent magnet 3. The magnetic flux lines of the uncovered second permanent magnet 4, not being squeezed by the magnetic flux lines of the first permanent magnet 3, will have greater magnetic leakage at their ends, resulting in low utilization of the second permanent magnet 4. Figure 13 The curves showing the utilization rates of the first and second permanent magnets as a function of α / β are presented. As α / β increases, the magnetic field lines of the first permanent magnet 3 increase, and its utilization rate initially increases. However, due to limitations in its flow path, the utilization rate of the first permanent magnet begins to decrease. Similarly, as α / β increases, the utilization rate of the second permanent magnet initially increases and then gradually stabilizes. Considering both the utilization rates of the first and second permanent magnets 4, a suitable range for α / β is selected.

[0144] Projecting along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2, within this projection plane, the angle between the two endpoints of the end of one pole of the first permanent magnet 3 near the outer circle of the rotor and the line connecting the rotor center is α, and the angle between the two endpoints of the end of one pole of the second permanent magnet 4 near the outer circle of the rotor and the line connecting the rotor center is γ. Then α / γ>1, preferably 2.0≤α / γ≤3.3.

[0145] By defining the relationship between α and γ, the leakage flux at the end of the second permanent magnet 4 can be reduced, while the utilization rate of the first permanent magnet 3 and the second permanent magnet 4 can be improved. Specifically, if α / γ is too large, the utilization rate of the first permanent magnet 3 is low; if α / γ is too small, the leakage flux at the end of the second permanent magnet 4 is large, and since the leakage flux does not contribute to the torque, the utilization rate of the second permanent magnet 4 is reduced. Figure 14 The curves shown depict the changes in the utilization rate of the first permanent magnet and the leakage flux coefficient at the end of the second permanent magnet as a function of α / γ. As α / γ increases, the utilization rate of the first permanent magnet initially increases and then decreases, while the leakage flux coefficient at the end of the second permanent magnet decreases until it gradually stabilizes. Considering both the utilization rate of the first permanent magnet and the leakage flux at the end of the second permanent magnet, the range of α / γ is selected.

[0146] In one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2. Within this projection plane, the pole arc angle of one pole of the second rotor core 2 is 360 / 2p, where 360 / 2p / α ≥ 1, and p is the number of pole pairs of the second rotor core 2. Preferably, 1.3 ≥ 360 / 2p / α ≥ 1.

[0147] By defining the relationship between α and the rotor pole arc, the space on the end face of the second rotor core 2 can be used to maximize the arrangement of the first permanent magnet 3, thereby increasing the output of the permanent magnet motor while ensuring that the rotor is not saturated. Specifically, when 360 / 2p / α = 1, α is equal to the pole arc angle of one pole of the rotor. At this time, the utilization rate of the end face space of the second rotor core 2 is the highest, and the rotor saturation degree is also high. When 360 / 2p / α > 1, α is less than the pole arc angle of one pole of the second rotor core 2. At this time, the utilization rate of the end face space of the second rotor core 2 decreases, and the rotor saturation degree also decreases.

[0148] By setting the values ​​of 360 / 2p / α, the utilization rate of the end face space of the second rotor core 2 and the rotor saturation degree can be adjusted simultaneously, limiting their ratio range so as to select a reasonable rotor saturation degree and maximize the utilization of the end face space of the second rotor core 2. Figure 15 The figure shows the curves of the end face space utilization rate and rotor saturation coefficient of the second rotor core 2 as a function of 360 / 2p / α. As 360 / 2p / α increases, the end face space utilization rate of the second rotor core 2 decreases, and the rotor saturation coefficient also decreases. It should be noted that a lower rotor saturation coefficient is not necessarily better. A suitable saturation coefficient allows for efficient use of the core. If the saturation coefficient is too low, it will result in excessive core volume and material waste; furthermore, it means too few magnetic lines of force, leading to a decrease in the output of the permanent magnet motor. This invention preferably achieves a high end face space utilization rate for the second rotor core and appropriate rotor saturation. If the operating conditions of the permanent magnet motor are different, both factors are considered, and the value of 360 / 2p / α is selected accordingly.

[0149] like Figure 8 As shown, in one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2. Within this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, and the area of ​​one pole of the second rotor core 2 is s2, where s1 / s2 ≥ 1. This rotor structure allows the magnetic lines of force of the first permanent magnet to flow through the second rotor core 2 into the air gap to interact with the stator magnetic field and generate torque. By limiting the proportional relationship between the areas of the first permanent magnet 3 and one pole of the second rotor core 2 within the projection plane, the ratio of the areas of one pole of the first permanent magnet 3 to one pole of the second rotor core 2 can be set more rationally. This improves the utilization rate of the second permanent magnet while ensuring the utilization rate of the first permanent magnet, reduces magnetic leakage at the rotor end, and enhances the overall utilization rate of the first permanent magnet 3 and the second permanent magnet 4, thereby improving the performance of the permanent magnet motor. Preferably, 1.05 ≤ s1 / s2 ≤ 1.95. More preferably, 1.25 ≤ s1 / s2 ≤ 1.85.

[0150] Here, by limiting the area of ​​the first permanent magnet 3 and the second rotor core 2, low utilization rates of the first permanent magnet 3 and the second permanent magnet 4 are avoided. For example... Figure 17 The curves showing the utilization rates of the first and second permanent magnets as a function of s1 / s2 are presented. Considering both the utilization rates of the first and second permanent magnets, the range of s1 / s2 is selected.

[0151] As can be seen from the attached diagram, when 1.25≤s1 / s2≤1.85, the comprehensive utilization rate of the first permanent magnet 3 and the second permanent magnet 4 is relatively high, which can make fuller use of the functions of the first permanent magnet 3 and the second permanent magnet 4 and improve the working performance of the permanent magnet motor.

[0152] In one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2. Within this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, and the area of ​​one pole of the second permanent magnet 4 is s3. In a cross-section passing through the central axis of the second rotor core 2, the area of ​​one pole of the first permanent magnet 3 is s4, and the area of ​​one pole of the second permanent magnet 4 is s5, where 0.8*s3≤s1≤2.4*s5, and / or 0.3*s3≤s4≤0.8*s5.

[0153] By limiting the area relationship between the first permanent magnet 3 and the second permanent magnet 4, it is ensured that both the first permanent magnet 3 and the second permanent magnet 4 can increase the output of the permanent magnet motor while possessing a certain degree of resistance to demagnetization. Specifically, s1 and s4 determine the contribution of the first permanent magnet 3 to the output of the permanent magnet motor and its resistance to demagnetization, respectively; s5 and s3 determine the contribution of the second permanent magnet 4 to the output of the permanent magnet motor and its resistance to demagnetization, respectively. Limiting the relationship between s1 and s3 ensures that s1 has a certain value, providing axial magnetic flux lines for the permanent magnet motor; limiting the relationship between s1 and s5 ensures that the flux linkages of the first permanent magnet 3 and the second permanent magnet 4 have an optimal ratio, reducing the impact of saturation on the utilization rate of the no-load flux linkage of the permanent magnet motor. Limiting the relationship between s4 and s3 ensures the resistance to demagnetization of the first permanent magnet 3 and the consistency of demagnetization between the first permanent magnet 3 and the second permanent magnet 4; limiting the relationship between s4 and s5 avoids oversaturation of the permanent magnet motor due to an excessively large s4.

[0154] like Figures 29 to 32 As shown, with the increase of s1 / s3, the unloaded flux linkage first increases linearly, and then the increasing trend gradually slows down. The value of s1 / s3 is selected at the inflection point of the linear increase of the unloaded flux linkage. With the increase of s1 / s5, the utilization rate of the unloaded flux linkage first increases and then decreases. When the permanent magnet motor is oversaturated, the utilization rate of the unloaded flux linkage drops sharply. The value of s1 / s5 is selected at the inflection point of the change in the utilization rate of the unloaded flux linkage. With the increase of s4 / s3, under the same demagnetizing current, the demagnetization rate of the first permanent magnet 3 decreases, and the demagnetization rate of the second permanent magnet 4 increases slightly. The difference in the demagnetization rates of the first permanent magnet 3 and the second permanent magnet 4 tends to decrease, and the consistency of their demagnetization becomes better. With the increase of s4 / s5, the saturation degree of the permanent magnet motor increases. The value of s4 / s5 is selected at the inflection point of the permanent magnet motor oversaturation.

[0155] In one embodiment, a projection is made onto one end face of the second rotor core 2 along its axial direction. Within this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, and the length of the line connecting the central axis of the second rotor core 2 and any point on its outer circle is j, where 1 ≤ s1 / max(j) ≤ 20. Preferably, 3 ≤ s1 / max(j) ≤ 16. More preferably, 5 ≤ s1 / max(j) ≤ 13.

[0156] Limiting the range of this ratio can enhance the magnetizing effect of the permanent magnet motor and increase its output. Specifically, if s1 / max(j) is too small, then either s1 being too small or max(j) being too large will lead to two situations: one is that because the area of ​​s1 is too small, the area it covers at the ends of the second permanent magnet 4 is too small, resulting in increased magnetic leakage at the ends of the second permanent magnet 4 and a weakened magnetizing effect of the permanent magnet motor; the other is that the number of pole pairs of the permanent magnet motor is too large, which is not conducive to the arrangement of the permanent magnets. If s1 / max(j) is too large, then either s1 being too large or max(j) being too small will lead to too few pole pairs of the permanent magnet motor and a weak magnetizing effect. Figure 33 The curves show the variation of the magnetic focusing effect coefficient of a permanent magnet motor with s1 / max(j). As s1 / max(j) increases, the magnetic focusing effect coefficient first increases and then decreases. That is, if s1 / max(j) is too large or too small, the magnetic focusing effect of the permanent magnet motor will be weakened.

[0157] In one embodiment, a projection is made onto one end face of the second rotor core 2 along the axial direction of the second rotor core 2. Within this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, the area of ​​one pole of the second rotor core 2 is s2, and the area of ​​one pole of the second permanent magnet 4 is s3, where 0.2 ≤ s2 / (s1+s3) ≤ 1. Preferably, 0.3 ≤ s2 / (s1+s3) ≤ 0.6.

[0158] Limiting the range of this ratio ensures that the magnetic field lines of the first and second permanent magnets have suitable magnetic circuit areas. On the one hand, it prevents the permanent magnet motor from saturating due to an excessively small magnetic circuit area, thus avoiding increased iron losses; on the other hand, it prevents the permanent magnet motor from becoming too large due to an excessively large magnetic circuit area, thus avoiding material waste. Figure 34 The curves show the changes in iron loss and the utilization rate of the second rotor core as a function of s2 / (s1+s3). As s2 / (s1+s3) increases, the saturation level of the permanent magnet motor decreases, and the iron loss decreases. After reaching a certain saturation level, the iron loss gradually stabilizes. After the saturation level of the permanent magnet motor decreases, the effective magnetic circuit area increases, and the magnetic lines of force can flow smoothly, increasing the utilization rate of the second rotor core. After reaching a certain saturation level, further increasing the magnetic circuit area will cause the utilization rate of the second rotor core to begin to decline.

[0159] See also Figure 6 and 39As shown, in one embodiment, the thickness of the first permanent magnet 3 along the axial direction of the second rotor core 2 is b. Projection is made onto one end face of the second rotor core 2 along the axial direction of the second rotor core 2. Within this projection plane, the sum of the angles formed by the lines connecting the two endpoints of each pole of the first permanent magnet 3 closest to the outer circumference of the rotor and the center of the second rotor core 2 is α*2q. The ratio of this sum of angles to the circumferential angle of the second rotor core 2 is a, where a = α*2q / 360, 2 ≤ b / a ≤ 6, and q is the number of pole pairs of the first permanent magnet 3. Preferably, 3 ≤ b / a ≤ 5.

[0160] Limiting the ratio of b to a ensures that the first permanent magnet has a certain axial thickness, enhancing its demagnetization resistance. Specifically, a = α * 2q / 360, where q is the number of pole pairs of the first permanent magnet 3, and a represents the total pole arc coefficient of the first permanent magnet 3. This value determines the range of the demagnetizing magnetic field directly borne by the first permanent magnet 3. When a is small, the range of the demagnetizing magnetic field borne by the first permanent magnet 3 is also small, and the axial thickness b required to ensure its demagnetization resistance is also small; conversely, the larger a value is, the smaller the range. Limiting the minimum value of b / a ensures the demagnetization resistance of the first permanent magnet 3; limiting the maximum value of b / a, while ensuring the demagnetization resistance of the first permanent magnet 3, avoids waste of the first permanent magnet 3 and reduces its utilization rate. Figure 16 The curves showing the demagnetization rate and utilization rate of the first permanent magnet as a function of b / a are shown. As b / a increases, the demagnetization rate of the first permanent magnet decreases under the same current and the decreasing trend slows down, but the utilization rate of the first permanent magnet decreases and the decreasing trend becomes larger. Taking into account the demagnetization resistance and utilization rate of the first permanent magnet, the range of b / a is selected.

[0161] In one embodiment, a projection is made onto one end face of the second rotor core 2 along its axial direction. Within this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, and the thickness of the first permanent magnet 3 along the axial direction of the second rotor core 2 is b. s1 is inversely proportional to b. The unit of area s1 is mm. 2 The thickness b is in mm.

[0162] In one embodiment, the relationship between s1 and b satisfies the dimensionless formula s1=-A*b+C, where the value of A ranges from 5 to 20, and the value of C ranges from 120 to 400.

[0163] By defining the relationship between s1 and b, the saturation level of the permanent magnet motor can be reduced, the utilization rate of the no-load flux linkage can be improved, and the iron loss of the permanent magnet motor can be reduced. Specifically, s1 represents the magnetic supply area of ​​one pole of the first permanent magnet 3. When the first permanent magnet 3 has a large magnetic supply area, the rotor can reach a suitable saturation level with a small axial thickness b. Increasing the value of b further will cause the rotor to become oversaturated, which will not only weaken the improvement effect of the no-load flux linkage but also increase the iron core loss; and vice versa. Therefore, s1 and b are inversely proportional. By defining the relationship curve between s1 and b, on the one hand, the utilization of the first permanent magnet 3 can be maximized to improve the flux linkage of the permanent magnet motor, reducing current and copper loss; on the other hand, the permanent magnet motor can be prevented from becoming oversaturated, reducing iron core loss. When copper loss and iron loss are balanced, the performance of the permanent magnet motor is optimal. Experiments have verified that, under a certain value of s1, by selecting an appropriate value of b, the proportions of iron loss and copper loss in the permanent magnet motor are 52% and 48%, respectively, basically reaching a balance. At this point, if the value of b is increased by another 1 mm, the iron loss of the permanent magnet motor increases by 10.2%, while the copper loss decreases by less than 1%, leading to a deterioration in the performance of the permanent magnet motor. For example... Figure 35 The figure shows the changing trends of iron loss and copper loss of permanent magnet motor as b increases under the same s1.

[0164] In one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2. In this projection plane, the sum of the included angles formed by the lines connecting the two endpoints of each pole of the first permanent magnet 3 near the outer circle of the rotor and the center of the second rotor core 2 is α*2q. The ratio of the sum of the included angles to the circumferential angle of the second rotor core 2 is a, where a = α*2q / 360, and 1.7 ≤ a*b ≤ 12.

[0165] Preferably, 2 ≤ a*b ≤ 10.

[0166] By limiting the product relationship between a and b, it is ensured that the first permanent magnet 3 occupies a certain angle on the second rotor core 2, thereby enhancing the magnetic field strength of the permanent magnet motor and increasing its output. Specifically, a = α * 2q / 360, where q is the number of pole pairs of the first permanent magnet 3, and a represents the total pole arc coefficient of the first permanent magnet 3, which determines the size of the magnetizing area of ​​the first permanent magnet 3. When a is small, the magnetizing area of ​​the first permanent magnet 3 is small, and a larger axial thickness b is required to achieve a suitable saturation level; conversely, the larger a is, the smaller a is. Limiting the minimum value of a * b ensures that the first permanent magnet 3 occupies a certain area on the second rotor core 2 to enhance the rotor magnetic field strength; limiting the maximum value of a * b ensures the rotor magnetic field strength while avoiding waste of the first permanent magnet 3. Figure 36 The curves showing the changes in air gap magnetic flux density and utilization rate of the first permanent magnet as a*b are shown. As a*b increases, the air gap magnetic flux density increases. After the magnetic circuit is saturated, the increase in air gap magnetic flux density gradually decreases, and the decrease in utilization rate of the first permanent magnet accelerates.

[0167] In one embodiment, the thickness of the second permanent magnet 4 along its magnetization direction is m, and 0.2≤b / m≤2.

[0168] Preferably, 0.4 ≤ b / m ≤ 1.4.

[0169] By defining the relationship between b and m, it is possible to ensure that both the first permanent magnet 3 and the second permanent magnet 4 possess a certain degree of resistance to demagnetization and that their demagnetization is consistent. Specifically, the demagnetization resistance of the first permanent magnet 3 depends on its axial thickness b, while the demagnetization resistance of the second permanent magnet 4 depends on its magnetization direction thickness m. Limiting the minimum value of b / m ensures the demagnetization resistance of both the first and second permanent magnets 4; limiting the range of b / m ensures the consistency of the demagnetization resistance of the first and second permanent magnets 4; limiting the maximum value of b / m reduces the cost of the permanent magnets while ensuring demagnetization resistance. Figure 18 The figure shows the demagnetization rates of the first and second permanent magnets as a function of b / m under the same demagnetizing current. As b / m increases, the demagnetization rate of the first permanent magnet decreases while the demagnetization rate of the second permanent magnet increases. The demagnetization consistency between the first and second permanent magnets first improves and then deteriorates. Considering the demagnetization resistance and demagnetization consistency of the permanent magnets, the range of b / m is selected.

[0170] In one embodiment, the thickness of the first rotor core 1 along the axial direction of the second rotor core 2 is c, where 0.1 ≤ c / b ≤ 1.

[0171] c is greater than or equal to the axial thickness of a single core lamination of the second rotor core 2.

[0172] By limiting the relationship between b and c, an optimal thickness ratio between the first rotor core 1 and the first permanent magnet 3 can be ensured, thereby increasing the output of the permanent magnet motor while also improving its utilization rate. Specifically, the magnetic lines of force of the first permanent magnet 3 form a loop along its axial direction through the first rotor core 1. The first rotor core 1 and the first permanent magnet 3 are directly adjacent to each other to avoid loss of magnetic lines of force during the flow process. Furthermore, the axial thickness of the first rotor core 1 determines the smoothness and saturation of the magnetic path for the flow of magnetic lines of force in the first permanent magnet 3. Limiting the minimum value of c / b ensures that the magnetic circuit of the first permanent magnet 3 is not saturated, thus increasing the flux linkage of the first permanent magnet 3; limiting the maximum value of c / b increases the utilization rate of the first rotor core 1 and reduces its cost. Figure 37 The curves showing the changes of the saturation coefficient and utilization rate of the first rotor core as a function of c / b are shown. As c / b increases, both the saturation coefficient and utilization rate of the first rotor core decrease. Taking into account the saturation degree and cost of the first rotor core, the range of c / b is selected.

[0173] See also Figure 7As shown, in one embodiment, a projection is made along the axial direction of the second rotor core 2 onto one end face of the second rotor core 2. Within this projection plane, the length of the line connecting the center of the second rotor core 2 to the center of the radially inner side of one pole of the first permanent magnet 3 is d, and the length of the line connecting the center of the second rotor core 2 to the center of the radially outer side of the first permanent magnet 3 is i, where 0.2 ≤ d / max(i) ≤ 0.8. Preferably, 0.3 ≤ d / max(i) ≤ 0.6.

[0174] Limiting the relationship of d / max(i) helps reduce the assembly difficulty of the permanent magnet motor and the machining difficulty of the first permanent magnet 3. Specifically, if d / max(i) is too small, the inner side of the first permanent magnet 3 will be too small or the outer side will be too large, resulting in a large assembly difficulty with the shaft and stator; if d / max(i) is too large, the inner side of the first permanent magnet 3 will be too large or the outer side will be too small, the distance between the inner and outer sides will be too small, the machining difficulty of the first permanent magnet 3 will increase, or even make it impossible to machine.

[0175] See also Figure 43 As shown, in one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the length of the line connecting the central axis of the second rotor core 2 and the center of the end edge of one pole of the first permanent magnet 3 near the outer circle of the rotor is i. The maximum value of the line connecting the central axis of the second rotor core 2 and each point on the outer circle of the second rotor core 2 is max(j), where max(i)≤max(j).

[0176] In one embodiment, the length of the line connecting the central axis of the second rotor core 2 and the center of the end edge of one pole of the second permanent magnet 4 near the outer circle of the rotor is ii, max(j)≥max(i)≥0.8*ii.

[0177] Preferably, max(j) ≥ max(i) ≥ 0.95*ii.

[0178] By defining the relationship between max(i), ii, and max(j), the length of the line connecting the rotor center and the center of the first permanent magnet 3 near the outer circle of the rotor can be limited. This increases the contribution of the first permanent magnet 3 / second permanent magnet 4 to the output of the permanent magnet motor and reduces the assembly difficulty of the permanent magnet motor. Specifically, the end of the second permanent magnet 4 near the outer circle of the rotor is prone to magnetic leakage (top magnetic leakage). The magnetic lines of force of the first permanent magnet 3 interrupt the magnetic leakage path of the second permanent magnet 4 by squeezing the magnetic lines of force at this point, thus weakening the top magnetic leakage. Defining the relationship between max(i) and ii ensures that the magnetic lines of force of the first permanent magnet 3 are within its effective range, effectively reducing the top magnetic leakage of the second permanent magnet 4. In addition, defining the relationship between max(j) and max(i) reduces the assembly precision requirements of the first permanent magnet 3, thus reducing the assembly difficulty of the permanent magnet motor. Figure 44 The curves shown represent the relationship between the leakage coefficient at the top of the second permanent magnet and max(i) / ii. As max(i) / ii increases, the leakage coefficient at the top of the second permanent magnet decreases, and the decreasing trend changes. When max(i) / ii is greater than 0.8, the slowing trend reaches its first inflection point; when max(i) / ii is greater than 0.95, the slowing trend reaches its second inflection point.

[0179] In one embodiment, the length of the line connecting the central axis of the second rotor core 2 and the center of the radial inner side of one pole of the first permanent magnet 3 is d, and the length of the line connecting the central axis of the second rotor core 2 and the center of the radial inner side of one pole of the second permanent magnet 4 is f, where 0≤d / f≤2.

[0180] Preferably, 0.8 ≤ d / f ≤ 1.6.

[0181] By limiting the d / f ratio, the length of the line connecting the rotor center and the center of the first permanent magnet 3 near the rotor shaft can be limited, thereby improving the utilization rate of the first permanent magnet 3 and the second permanent magnet 4. Specifically, the end of the second permanent magnet 4 near the rotor shaft is prone to magnetic leakage (bottom magnetic leakage). The magnetic lines of force of the first permanent magnet 3, by squeezing the magnetic lines of force of the second permanent magnet 4 at this point, cuts off the bottom magnetic leakage path and suppresses the bottom magnetic leakage of the second permanent magnet 4. By limiting the maximum value of d / f, it is avoided that the second permanent magnet 4 exceeds the effective range of the magnetic lines of force of the first permanent magnet 3 by too much, which would increase its bottom magnetic leakage and reduce the utilization rate of the second permanent magnet. By limiting the minimum value of d / f, it is avoided that the first permanent magnet 3, due to its small inner volume, would weaken its axial magnetic lines, resulting in material waste and low utilization. Figure 45The figure shows the relationship between the leakage magnetic coefficient at the bottom of the second permanent magnet, the utilization rate of the first permanent magnet, and d / f. As d / f increases, the leakage magnetic coefficient at the bottom of the second permanent magnet increases, and the increase is relatively slow when d / f is less than 1.6. Then, a second inflection occurs when d / f is 2. As d / f increases, the utilization rate of the first permanent magnet increases first. Then, due to the reduction in the inner part of the first permanent magnet affecting the axial magnetic field lines, the utilization rate of the first permanent magnet begins to decrease.

[0182] See also Figure 7 As shown, in one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the length of the line connecting the central axis of the second rotor core 2 and the center of the end edge of one pole of the first permanent magnet 3 near the outer circle of the rotor is i, the length of the line connecting the central axis of the second rotor core 2 and each point on the outer circle of the second rotor core 2 is j, and the length of the line connecting the central axis of the second rotor core 2 and each point on the outer circle of the first rotor core 1 is h, max(h)≤max(j), and / or, min(h)≥0.8*max(i).

[0183] In one embodiment, 0.9 ≤ min(h) / max(i) ≤ 1.4.

[0184] In one embodiment, 1 ≤ min(h) / max(i) ≤ 1.3.

[0185] By limiting the size of the first rotor core 1, the assembly difficulty of the permanent magnet motor can be reduced while minimizing magnetic leakage near the outer circumference of the first permanent magnet 3. Specifically, by limiting the maximum value of h, a certain width of air gap can be formed between the rotor cores (first rotor core 1 and second rotor core 2) and the stator core 12, reducing the difficulty of assembling the rotor into the stator; by limiting the minimum value of h, it can be ensured that the magnetizing surface of the first permanent magnet 3 has an effective magnetic circuit, and magnetic leakage will not occur due to the lack of an effective axial main magnetic circuit. Figure 47 The figure shows the relationship between the unloaded magnetic flux and min(h) / max(i). As min(h) / max(i) increases, the unloaded magnetic flux increases, but the magnitude of the increase decreases. When min(h) / max(i) is less than 0.8, the unloaded magnetic flux is small due to the large leakage flux of the first permanent magnet. When min(h) / max(i) is greater than 1.4, the unloaded magnetic flux basically does not change because the magnetic lines of force of the first permanent magnet have completely passed through the magnetic circuit.

[0186] In one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the length of the line connecting the center axis of the second rotor core 2 and the center of the radial inner side of one pole of the first permanent magnet 3 is d, and the length of the line connecting each point of the center axis of the second rotor core 2 and the radial inner side of the first rotor core 1 is k, where max(k)≤d.

[0187] In one embodiment, 0.2 ≤ max(k) / d ≤ 1.

[0188] By limiting the size of the first rotor core 1, the leakage flux of the first permanent magnet 3 near the shaft can be reduced. Specifically, by limiting the maximum value of k, it is ensured that the end of the first permanent magnet 3 near the shaft has an axial main magnetic circuit, thereby avoiding leakage flux caused by the absence of a main magnetic circuit. Figure 48 The curves showing the relationship between the unloaded flux linkage and max(k) / d are shown. When max(k) / d is less than 0.2, the increase in unloaded flux linkage is small due to the large margin of the main magnetic circuit area of ​​the first permanent magnet 3. When max(k) / d is greater than 1, the decrease in unloaded flux linkage is larger due to the restricted flow path of the magnetic lines of force of the first permanent magnet 3.

[0189] In one embodiment, the thickness of the first rotor core 1 along the axial direction of the permanent magnet motor is c, and the thickness of the second permanent magnet 4 along its magnetization direction is m, where 0.1*m≤c≤m.

[0190] In one embodiment, 0.1*m≤c≤0.5*m.

[0191] By limiting the relationship between c and m, on the one hand, the magnetic flux density of the first rotor core 1 will not become oversaturated due to its insufficient thickness, resulting in a decrease in the utilization rate of the no-load flux linkage and thus reducing the output of the permanent magnet motor. On the other hand, the core loss of the first rotor core 1 can be minimized, thereby reducing the loss of the permanent magnet motor. Figure 19 The figure shows the curves of no-load flux utilization and iron loss of permanent magnet motor as a function of c / m. When c / m is less than 0.1, the no-load flux utilization is low. When c / m is greater than 1, the iron loss increases significantly. In the range of c / m from 0.1 to 1, the no-load flux utilization gradually increases to a stable level, and the increasing trend of iron loss shows signs of slowing down. In the range of c / m from 0.1 to 0.5, the no-load flux utilization increases basically linearly.

[0192] See also Figure 40As shown, in one embodiment, a magnetic shielding groove 11 is provided on the side of the mounting groove near the central axis of the second rotor core 2; a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2, and in this projection plane, the projection of the first permanent magnet 3 is configured to partially cover the projection of the magnetic shielding groove 11, that is, the projection of the first permanent magnet 3 and the projection of the magnetic shielding groove 11 partially overlap.

[0193] In one embodiment, the area of ​​the projection of the first permanent magnet 3 covering the projection of the magnetic isolation groove 11 is less than or equal to 75% of the projected area of ​​the magnetic isolation groove 11.

[0194] In one embodiment, the area of ​​the projection of the first permanent magnet 3 covering the projection of the magnetic isolation groove 11 is less than or equal to 25% of the projected area of ​​the magnetic isolation groove 11.

[0195] By defining the projection relationship between the first permanent magnet 3 and the magnetic isolation groove 11, the saturation effect of the second rotor core 2 caused by the first permanent magnet 3 can be reduced, and the utilization rate of the first permanent magnet can be improved. Specifically, only some of the reinforcing ribs around the magnetic isolation groove 11 are magnetically conductive. If the first permanent magnet 3 completely covers the magnetic isolation groove 11, the magnetic conductive area in this part will be small and the saturation degree will be high. From another perspective, the magnetic circuit area of ​​the first permanent magnet 3 covering this part is limited, and some of the magnetic flux generated by the first permanent magnet 3 becomes ineffective magnetic flux due to the lack of a magnetic circuit, resulting in low utilization of the first permanent magnet.

[0196] like Figure 42 The figure shows the utilization rate of the unloaded magnetic flux and the first permanent magnet under different coverage areas. Verification showed that compared to 100% coverage, when the coverage area is 80%, the unloaded magnetic flux decreases by only 2.3%, and the cost of the first permanent magnet decreases by 8.9%; compared to 100% coverage, when the coverage area is 70%, the unloaded magnetic flux decreases by 6.2%, and the cost of the first permanent magnet decreases by 14.8%; compared to 100% coverage, when the coverage area is 20%, the unloaded magnetic flux decreases by 7.8%, but the cost of the first permanent magnet is saved by 20.8%. This invention preferably uses a coverage area that minimizes the reduction in unloaded magnetic flux but maximizes the reduction in permanent magnet cost. However, other coverage areas provided by this invention can also be selected if the high efficiency of the permanent magnet motor is considered.

[0197] See also Figure 9 As shown, in one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the minimum value of the radial width e of the first permanent magnet 3 is min(e), and the maximum value of the radial width g of the second permanent magnet 4 is max(g), where 0.5≤min(e) / max(g)≤2.

[0198] In one embodiment, 0.6 ≤ min(e) / max(g) ≤ 1.6.

[0199] In one embodiment, 0.8 ≤ min(e) / max(g) ≤ 1.6.

[0200] By limiting the relationship between the radial widths of the first permanent magnet 3 and the second permanent magnet 4, rotor leakage flux can be reduced, thereby improving the output and efficiency of the permanent magnet motor. Specifically, the range of min(e) / max(g) is limited so that the second permanent magnet 4 is within the range where the magnetic lines of force of the first permanent magnet 3 can act, thus reducing rotor leakage flux. Figure 49 The figure shows the relationship between the leakage flux coefficient of the permanent magnet motor and min(e) / max(g). When min(e) / max(g) is less than 0.5, the leakage flux of the second permanent magnet 4 is large, resulting in a large leakage flux coefficient. When min(e) / max(g) is greater than 2, the magnetic lines of the first permanent magnet 3 and the second permanent magnet 4 have a good mutual squeezing effect, and the leakage flux coefficient has basically no change. In the range of min(e) / max(g) from 0.5 to 2, the leakage flux coefficient increases and decreases accordingly, and the decrease is large in the range of 0.6 to 1.6.

[0201] In one embodiment, the maximum value of the radial width o of the second rotor core 2 is max(o), and max(e) ≤ max(o).

[0202] In one embodiment, 0.3 ≤ max(e) / min(o) ≤ 1.

[0203] In one embodiment, 0.4 ≤ max(e) / max(o) ≤ 0.95.

[0204] By defining the relationship between the radial widths of the first permanent magnet 3 and the second rotor core 2, the magnetizing surface of the first permanent magnet 3 and its magnetic circuit cross-sectional area can be appropriately matched, which can reduce the saturation of the second rotor core 2, reduce the core loss of the second rotor core 2, and improve the efficiency of the permanent magnet motor. Figure 50 The curves shown represent the variation of the saturation coefficient of the second rotor core with max(e) / min(o) and max(e) / max(o). When max(e) / min(o) is less than 0.3 or max(e) / max(o) is less than 0.4, the saturation coefficient of the second rotor core is small and basically unchanged, which will lead to low magnetic flux density of the permanent magnet motor and affect the output of the permanent magnet motor. When max(e) / min(o) is greater than 1 or max(e) / max(o) is greater than 0.95, the saturation coefficient of the second rotor core increases more significantly, its iron loss increases, and its performance decreases.

[0205] In one embodiment, the radial width of the first rotor core 1 is l, and 0.7 ≤ min(l) / max(e) ≤ 3.

[0206] In one embodiment, 1 ≤ min(l) / max(e) ≤ 2.

[0207] By defining the relationship between the radial widths of the first permanent magnet 3 and the first rotor core 1, the magnetizing surface of the first permanent magnet 3 and its magnetic circuit cross-sectional area can be appropriately matched, which can reduce the saturation of the first rotor core 1, reduce the core loss of the first rotor core 1, and improve the efficiency of the permanent magnet motor. Figure 51 The figure shows the curve of the first rotor core saturation coefficient as a function of min(l) / max(e). When min(l) / max(e) is less than 0.7, the first rotor core saturation coefficient is high, and its iron loss is high. When min(l) / max(e) is greater than 3, the first rotor core saturation coefficient has basically no change. In the range of min(l) / max(e) from 0.7 to 3, the first rotor core saturation coefficient decreases as min(l) / max(e) increases, and the decrease is relatively large in the range of 1 to 2.

[0208] See also Figure 38 and Figure 46 As shown, in one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the area of ​​one pole of the first permanent magnet 3 is s1, and the axial height of the second rotor core 2 along its own central axis is x. s1 is inversely proportional to x.

[0209] In one embodiment, s1 = -B*x + D, where the value of B ranges from 25 to 100, and the value of D ranges from 400 to 1600.

[0210] By defining the relationship between s1 and x, a suitable ratio of the first permanent magnet 3 and the second rotor core 2 can be achieved, improving the utilization rate of the first permanent magnet 3 and the second rotor core 2 while reducing the copper loss and core loss of the permanent magnet motor. Specifically, s1 represents the magnetizing area of ​​one pole of the first permanent magnet 3, which determines the strength of the axial magnetic field, while x determines the strength of the tangential / radial magnetic field. When s1 is large, the axial magnetic field is strong, and the permanent magnet motor can reach an optimal saturation level with a smaller tangential / radial magnetic field strength, and vice versa. At this point, further increasing s1 or x will enhance the axial magnetic field or the tangential / radial magnetic field, but because the permanent magnet motor is already saturated, the decrease in copper loss is small, while the increase in iron loss is significant. The utilization rate of the first permanent magnet 3 and the second rotor core 2 decreases, resulting not only in reduced permanent magnet motor performance but also in material waste. Therefore, s1 and x are inversely proportional. Furthermore, by further defining the relationship between s1 and x, the copper loss and iron loss of the permanent magnet motor can be balanced under different ratios of axial and tangential magnetic fields, thereby improving performance. Figure 53The figure shows the curve of permanent magnet motor loss versus s1 at a certain x. As s1 increases, the flux linkage provided by the first permanent magnet 3 increases, and the copper loss decreases until the permanent magnet motor saturates, at which point the copper loss essentially stops changing. As s1 increases, the degree of permanent magnet motor saturation increases, and the iron loss increases. The s1 at which the copper loss and iron loss reach equilibrium is the optimal ratio of s1 to x.

[0211] In one embodiment, the diameters of the first permanent magnets 3 at both ends of the second rotor core 2 are the same. This arrangement allows the magnetic lines of force of the first permanent magnets 3 on both ends of the second rotor core 2 to form a closed loop, increasing the magnetic flux of the permanent magnet motor. It also helps to counteract the axial forces at both ends of the rotor.

[0212] In one embodiment, the number of pole pairs of the first permanent magnet 3 is q, and the number of pole pairs of the second rotor core 2 is p, where q ≤ p. Preferably, q = p. By limiting the relationship between q and p, the output torque of the permanent magnet motor can be increased while maximizing the utilization rate of the first permanent magnet.

[0213] In one embodiment, a projection is made on one end face of the second rotor core 2 along the axial direction of the second rotor core 2. In this projection plane, the side of the first permanent magnet 3 near the outer circle of the rotor is an arc and / or a straight line, and / or the side wall of the first permanent magnet 3 near the central axis of the second rotor core 2 is an arc and / or a straight line. On the one hand, the shape of the first permanent magnet 3 can be flexibly selected according to the space of the rotor end face to simplify its rotor structure. On the other hand, the shape of the first permanent magnet 3 can be set according to the processing requirements to reduce processing costs.

[0214] In one embodiment, a counterweight structure is provided on the first rotor core 1 to adjust the dynamic balance of the permanent magnet motor, and is not limited to a specific shape and material.

[0215] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0216] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0217] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A permanent magnet motor, characterized in that, It includes a stator structure and a rotor structure, wherein the stator structure is sleeved outside the rotor structure, and the rotor structure includes: First rotor core (1); The second rotor core (2) has multiple mounting slots spaced apart along the circumferential direction. The first permanent magnet (3) is axially magnetized, and multiple first permanent magnets (3) are arranged circumferentially along the central axis of the second rotor core (2); The second permanent magnet (4) is installed in the mounting slot; The first permanent magnet (3) is provided at both ends of the second rotor core (2), and the first rotor core (1) is provided on the side of the first permanent magnet (3) away from the second rotor core (2). The stator structure includes a stator core (12); The total height of the rotor structure along the axis of the permanent magnet motor is z, and the height of the stator core (12) along the axis of the permanent magnet motor is y, z / y≤4; The outer diameter of the first permanent magnet (3) located at at least one end of the second rotor core (2) is smaller than the inner diameter of the stator core (12); Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), within the projection plane, the area of ​​one pole of the first permanent magnet (3) is s1, the area of ​​one pole of the second rotor core (2) is s2, the area of ​​one pole of the second permanent magnet (4) is s3, and 0.2≤s2 / (s1+s3)≤1.

2. The permanent magnet motor according to claim 1, characterized in that, 1.0≤z / y≤3.

0.

3. The permanent magnet motor according to claim 1, characterized in that, The outer diameter of the first permanent magnet (3) located at at least one end of the second rotor core (2) is smaller than the largest diameter of the outer diameter of the first rotor core (1) and the second rotor core (2).

4. The permanent magnet motor according to claim 1, characterized in that, The stator structure includes a stator core (12), the second rotor core (2) has a height of x along the axial direction of the permanent magnet motor, the stator core (12) has a height of y along the axial direction of the permanent magnet motor, and x / y≤2.

5. The permanent magnet motor according to claim 4, characterized in that, 0.5≤x / y≤1.

5.

6. The permanent magnet motor according to claim 5, characterized in that, 0.5≤x / y≤0.

98.

7. The permanent magnet motor according to claim 1, characterized in that, The height of the second rotor core (2) along the axial direction of the permanent magnet motor is x, the height of the stator core (12) along the axial direction of the permanent magnet motor is y, the height of the first permanent magnet (3) along the axial direction of the permanent magnet motor is b, 0.01x≤b≤0.7x; and / or, 0.015y≤b≤0.9y.

8. The permanent magnet motor according to claim 1, characterized in that, An air gap is formed between the stator structure and the rotor structure. The difference between the maximum outer diameter of the second rotor core (2) of the rotor structure and the maximum outer diameter of the first permanent magnet (3) is w, where w ≥ 0.

9. The permanent magnet motor according to claim 8, characterized in that, The thickness of the air gap is δ, 0.5*min(δ)≤w≤14*min(δ).

10. The permanent magnet motor according to claim 1, the projection is made on the end face of the second rotor core (2) along the axial direction of the second rotor core (2), and in the projection plane, the area of ​​one pole of the first permanent magnet (3) is s1, the axial height of the second rotor core (2) along its own central axis is x, and s1 is inversely proportional to x.

11. The permanent magnet motor according to claim 10, characterized in that, s1 = -B*x + D, where the value of B ranges from 25 to 100, and the value of D ranges from 400 to 1600.

12. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), within the projection plane, the area of ​​one pole of the first permanent magnet (3) is s1, the area of ​​one pole of the second rotor core (2) is s2, and s1 / s2≥1.

13. The permanent magnet motor according to claim 12, characterized in that, 1.05≤s1 / s2≤1.

95.

14. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), within the projection plane, the area of ​​one pole of the first permanent magnet (3) is s1, the area of ​​one pole of the second permanent magnet (4) is s3, and within the cross section passing through the central axis of the second rotor core (2), the area of ​​one pole of the first permanent magnet (3) is s4, and the area of ​​one pole of the second permanent magnet (4) is s5, where 0.8*s3≤s1≤2.4*s5, and / or 0.3*s3≤s4≤0.8*s5.

15. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), in the projection plane, the angle between the two endpoints of one pole of the first permanent magnet (3) near the outer circle of the rotor and the center of the second rotor core (2) is α, and the angle between the two endpoints of the magnetically conductive part of one pole of the second rotor core (2) near the outer circle of the rotor and the center of the second rotor core (2) is β, α / β≥1.

16. The permanent magnet motor according to claim 15, characterized in that, 1≤α / β≤1.62。 17. The permanent magnet motor according to claim 1, characterized in that, A magnetic shielding groove (11) is provided on the side of the mounting groove near the central axis of the second rotor core (2); a projection is made on one end face of the second rotor core (2) along the axial direction of the second rotor core (2), and the projection of the first permanent magnet (3) is configured to partially cover the projection of the magnetic shielding groove (11) in the projection plane.

18. The permanent magnet motor according to claim 17, characterized in that, The area of ​​the projection of the first permanent magnet (3) covering the projection of the magnetic isolation groove (11) is less than or equal to 75% of the projected area of ​​the magnetic isolation groove (11).

19. The permanent magnet motor according to claim 18, characterized in that, The area of ​​the projection of the first permanent magnet (3) covering the projection of the magnetic isolation groove (11) is less than or equal to 25% of the projected area of ​​the magnetic isolation groove (11).

20. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), within the projection plane, the area of ​​one pole of the first permanent magnet (3) is s1, and the thickness of the first permanent magnet (3) along the axial direction of the second rotor core (2) is b, with s1 being inversely proportional to b.

21. The permanent magnet motor according to claim 20, characterized in that, The relationship between s1 and b satisfies the dimensionless formula s1=-A*b+C, where the value of A ranges from 5 to 20, and the value of C ranges from 120 to 400.

22. The permanent magnet motor according to claim 1, characterized in that, 0.3≤s2 / (s1+s3)≤0.

6.

23. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), in the projection plane, the length of the line connecting the central axis of the second rotor core (2) and the center of the end edge of one pole of the first permanent magnet (3) near the outer circle of the rotor is i, and the maximum value of the line connecting the central axis of the second rotor core (2) and each point on the outer circle of the second rotor core (2) is max(j), max(i)≤max(j).

24. The permanent magnet motor according to claim 23, characterized in that, The length of the line connecting the central axis of the second rotor core (2) and the center of the end edge of one pole of the second permanent magnet (4) near the outer circle of the rotor is ii, max(j)≥max(i)≥0.8*ii.

25. The permanent magnet motor according to claim 24, characterized in that, max(j)≥max(i)≥0.95*ii.

26. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), within the projection plane, the minimum value of the radial width e of the first permanent magnet (3) is min(e), and the maximum value of the radial width g of the second permanent magnet (4) is max(g), where 0.5≤min(e) / max(g)≤2.

27. The permanent magnet motor according to claim 26, characterized in that, 0.6≤min(e) / max(g)≤1.

6.

28. The permanent magnet motor according to claim 1, characterized in that, Projecting along the axial direction of the second rotor core (2) onto one end face of the second rotor core (2), in the projection plane, the sum of the angles formed by the lines connecting the two endpoints of each pole of the first permanent magnet (3) near the outer circle of the rotor and the center of the second rotor core (2) is α*2q. The ratio of the sum of the angles to the circumferential angle of the second rotor core (2) is a, a=α*2q / 360. The thickness of the first permanent magnet (3) along the axial direction of the second rotor core (2) is b, 2≤b / a≤6, where q is the number of pole pairs of the first permanent magnet (3).

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