Motor rotor and self-starting synchronous reluctance motor

Abstract

The application provides a motor rotor and a self-starting synchronous reluctance motor. The motor rotor comprises a rotor core, the rotor core comprises a first core section at two ends and a second core section in the middle, the first core section is stacked by first core punching sheets, the second core section is stacked by second core punching sheets, in a cross section perpendicular to a central axis of the rotor core, the first core punching sheet comprises a first D-axis magnetic barrier slot extending along a D-axis direction, each first D-axis magnetic barrier slot comprises a first outer aluminum casting slot at two ends and an inner aluminum casting slot in the middle, the second core punching sheet comprises a second D-axis magnetic barrier slot extending along the D-axis direction, each second D-axis magnetic barrier slot comprises a second outer aluminum casting slot at two ends, the second outer aluminum casting slots at the two ends are separated by a flat plate isolation layer, and the flat plate isolation layer is arranged corresponding to the inner aluminum casting slot. According to the motor rotor, the eddy current path can be cut off, and the eddy current loss can be effectively reduced.

Description

Technical Field

[0001] This application relates to the field of motor technology, specifically to a motor rotor and a self-starting synchronous reluctance motor. Background Technology

[0002] Direct-start synchronous reluctance motors combine the structural features of induction motors and synchronous reluctance motors. They achieve starting by generating torque through squirrel-cage induction and constant-speed operation by generating reluctance torque through the rotor inductance difference. They can be directly powered for starting and operation. Compared to direct-start permanent magnet motors, direct-start synchronous reluctance motors do not use rare-earth permanent magnet materials and do not suffer from demagnetization issues, resulting in lower motor costs and higher reliability. Compared to asynchronous motors, they offer higher efficiency and constant speed. Furthermore, direct-start synchronous reluctance motors can self-start without a controller, further reducing costs.

[0003] Self-starting motors generate starting torque by having the rotor bars cut the stator magnetic field. The rotor bars are made of conductive but non-magnetic material, typically pure aluminum, filled using a high-pressure die-casting process. After casting, end rings are formed at both ends of the rotor, short-circuiting all or some of the bars. However, longer bars can generate eddy currents, causing the rotor to heat up and thus reducing the motor's performance. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this application is to provide a motor rotor and a self-starting synchronous reluctance motor that can isolate the eddy current path and effectively reduce eddy current loss.

[0005] To address the aforementioned problems, this application provides a motor rotor, including a rotor core. The rotor core includes first core segments at both ends and a second core segment in the middle. The first core segment is formed by stacking first core laminations, and the second core segment is formed by stacking second core laminations. In a cross-section perpendicular to the central axis of the rotor core, the first core lamination includes a first D-axis magnetic barrier groove extending along the D-axis direction. Each first D-axis magnetic barrier groove includes a first outer cast aluminum groove at both ends and an inner cast aluminum groove in the middle. The second core lamination includes a second D-axis magnetic barrier groove extending along the D-axis direction. Each second D-axis magnetic barrier groove includes a second outer cast aluminum groove at both ends. The second outer cast aluminum grooves at both ends are separated by a flat plate isolation layer, which is disposed corresponding to the inner cast aluminum groove.

[0006] Preferably, the first and second outer cast aluminum grooves have the same structure and are in the same position.

[0007] Preferably, the first outer cast aluminum groove and the inner cast aluminum groove are separated by an inner magnetic bridge.

[0008] Preferably, the rotor core has a Q-axis magnetic barrier groove on the outermost side in the Q-axis direction.

[0009] Preferably, an outer magnetic bridge is provided on the outer periphery of the Q-axis magnetic barrier groove, the first D-axis magnetic barrier groove, and the second D-axis magnetic barrier groove.

[0010] Preferably, the rotor core includes two first core segments and one second core segment. The axial height of the second core segment is L2, and the thickness of a single second core lamination is δ, where δ≤L2.

[0011] Preferably, the rotor core includes three first core segments and two second core segments, wherein the axial height of the two first core segments located at both ends is L1, the axial height of the first core segment located between the two second core segments is L3, the axial height of each second core segment is L2, and the axial height of the rotor core is L, where L1≥1 / 3L, L2<L3≤1 / 3L, and L2>0.

[0012] Preferably, the first outer cast aluminum groove, the inner cast aluminum groove, and the second outer cast aluminum groove are filled with conductive but non-magnetic material to form a conductor bar, and end rings are formed at both ends of the rotor core, and the end rings are connected to the conductor bar to form a short-circuit ring.

[0013] Preferably, the end ring is circular, with its inner diameter being greater than or equal to the diameter of the shaft hole of the rotor core, and its outer diameter being less than or equal to the outer diameter of the rotor core.

[0014] According to another aspect of this application, a self-starting synchronous reluctance motor is provided, including a motor rotor, which is the motor rotor described above.

[0015] The motor rotor provided in this application includes a rotor core, which includes a first core segment at both ends and a second core segment in the middle. The first core segment is formed by stacking first core laminations, and the second core segment is formed by stacking second core laminations. In a cross-section perpendicular to the central axis of the rotor core, the first core lamination includes a first D-axis magnetic barrier groove extending along the D-axis direction. Each first D-axis magnetic barrier groove includes a first outer cast aluminum groove at both ends and an inner cast aluminum groove in the middle. The second core lamination includes a second D-axis magnetic barrier groove extending along the D-axis direction. Each second D-axis magnetic barrier groove includes a second outer cast aluminum groove at both ends. The second outer cast aluminum grooves at both ends are separated by a flat plate isolation layer, which is provided corresponding to the inner cast aluminum groove. The rotor core is composed of two types of rotor laminations. The second core segment, formed by the second core lamination with a flat isolation layer in the inner aluminum slot, can isolate the guide bars of the first core segment with cast aluminum in the inner aluminum slot. This improves the eddy current problem caused by excessively long guide bars, effectively blocks the eddy current path, segments it, weakens or eliminates the eddy current, reduces rotor heating, and thus improves motor performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a motor rotor according to an embodiment of this application;

[0017] Figure 2 This is a schematic diagram of the structure of a motor rotor according to an embodiment of this application;

[0018] Figure 3 This is a schematic diagram of the first rotor lamination structure of a motor rotor according to an embodiment of this application;

[0019] Figure 4 This is a schematic diagram of the second rotor lamination structure of a motor rotor according to an embodiment of this application;

[0020] Figure 5 This is a schematic diagram of the structure of a motor rotor according to an embodiment of this application;

[0021] Figure 6 This is a diagram showing the relationship between the thickness and performance of the second core segment of a motor rotor according to one embodiment of this application.

[0022] Figure 7 This is a comparison chart of the efficiency of a motor rotor according to an embodiment of this application and a motor rotor in related technologies.

[0023] The reference numerals in the attached figures are as follows:

[0024] 1. First core segment; 2. Second core segment; 3. First core lamination; 4. Second core lamination; 5. First D-axis magnetic barrier groove; 6. Second D-axis magnetic barrier groove; 7. First outer cast aluminum groove; 8. Inner cast aluminum groove; 9. Second outer cast aluminum groove; 10. Flat plate isolation layer; 11. Inner magnetic bridge; 12. Outer magnetic bridge; 13. Q-axis magnetic barrier groove; 14. Conductor bar; 15. End ring. Detailed Implementation

[0025] See also Figures 1 to 7 As shown, according to an embodiment of this application, the motor rotor includes a rotor core, which includes a first core segment 1 located at both ends and a second core segment 2 located in the middle. The first core segment 1 is formed by stacking first core laminations 3, and the second core segment 2 is formed by stacking second core laminations 4. In a cross section perpendicular to the central axis of the rotor core, the first core lamination 3 includes a first D-axis magnetic barrier groove 5 extending along the D-axis direction. Each first D-axis magnetic barrier groove 5 includes a first outer cast aluminum groove 7 located at both ends and an inner cast aluminum groove 8 located in the middle. The second core lamination 4 includes a second D-axis magnetic barrier groove 6 extending along the D-axis direction. Each second D-axis magnetic barrier groove 6 includes a second outer cast aluminum groove 9 located at both ends. The second outer cast aluminum grooves 9 at both ends are separated by a flat plate isolation layer 10, which is provided corresponding to the inner cast aluminum groove 8.

[0026] The rotor core is composed of two types of rotor laminations. The second core segment 2, formed by the second core lamination 4 where the inner aluminum slot is located is a flat isolation layer 10, can isolate the guide bar 14 of the first core segment 1 of the inner aluminum slot 8. This improves the eddy current problem caused by the excessive length of the guide bar 14, effectively blocks the eddy current path, segments it, weakens or eliminates the eddy current, reduces rotor heating, and thus improves motor performance.

[0027] In one embodiment, the first external aluminum casting groove 7 and the second external aluminum casting groove 9 have the same structure and the same position.

[0028] In this embodiment, the motor rotor includes a first core lamination 3 and a second core lamination 4 with a special structure. The first core lamination 3 has multiple sets of magnetic barrier slots, the number of which corresponds to the number of rotor poles. Based on the shape of the magnetic barrier slots, the radial direction parallel to the slots is the D-axis, and the radial direction perpendicular to the slots is the Q-axis. The cast aluminum slots of the first core lamination 3 are divided into two layers: an outer cast aluminum slot 7 and an inner cast aluminum slot 8. Adjacent first D-axis magnetic barrier slots 5 form a magnetic conductive channel. The difference between the first core lamination 3 and the second core lamination 4 lies in the presence or absence of the inner cast aluminum slot 8. The second core lamination 4 also has multiple cast aluminum slots, and the outer cast aluminum slots are identical. However, the inner cast aluminum slots of the second core lamination 4 are replaced by a flat plate isolation layer 10, thus sealing the inner cast aluminum slots on the second core lamination 4. The thickness of the flat plate isolation layer 10 is the same as the axial thickness of the second core lamination 4. In one embodiment, the number of rotor pole pairs P = 2.

[0029] In one embodiment, the first outer cast aluminum groove 7 and the inner cast aluminum groove 8 are separated by an inner magnetic bridge 11. The main reason for separating the first outer cast aluminum groove 7 and the inner cast aluminum groove 8 with the inner magnetic bridge 11 is to increase the strength of the rotor structure. The aluminum casting process involves injecting molten aluminum into the rotor grooves through high temperature and high pressure. If the rotor structure is not strong enough, the aluminum casting process can easily damage the rotor structure, causing it to deform or even render it unusable. The presence of the inner magnetic bridge 11 can effectively prevent this phenomenon from occurring.

[0030] In one embodiment, the rotor core has a Q-axis magnetic barrier slot 13 on its outermost side in the Q-axis direction. The width of the Q-axis magnetic barrier slot 13 should be as wide as possible to ensure the amount of aluminum cast in the Q-axis magnetic barrier slot 13 and improve the starting capability of the motor rotor.

[0031] In one embodiment, an outer magnetic bridge 12 is provided on the outer periphery of the Q-axis magnetic barrier groove 13, the first D-axis magnetic barrier groove 5, and the second D-axis magnetic barrier groove 6, which can improve the structural strength of the motor.

[0032] In this embodiment, the motor rotor is non-magnetic and is produced by high-temperature and high-pressure die casting using an all-aluminum casting method. All magnetic barrier slots on the rotor are filled with molten aluminum to form guide bars 14. The rotor core is composed of a first core lamination 3 and a second core lamination 4 axially laminated together, allowing the guide bars to be separated by the flat insulating layer 10 on the second core lamination 4, thus reducing eddy current losses. The aluminum filling in the casting slots may not be aluminum; it can be other conductive but non-magnetic materials, such as copper.

[0033] In one embodiment, the rotor core includes two first core segments 1 and one second core segment 2. The axial height of the second core segment 2 is L2, and the thickness of a single second core lamination 4 is δ, where δ ≤ L2. In this embodiment, the second core segment 2 formed by the second core lamination 4 is located between the two first core segments 1 to isolate the connection of the guide bars 14 within the inner cast aluminum groove 8.

[0034] In one embodiment, the rotor core includes three first core segments 1 and two second core segments 2, wherein the axial height of the two first core segments 1 located at both ends is L1, the axial height of the first core segment 1 located between the two second core segments 2 is L3, the axial height of each second core segment 2 is L2, and the axial height of the rotor core is L, where L1≥1 / 3L and L2<L3≤1 / 3L.

[0035] The function of the second core lamination 4, stacked within the rotor core, is to cut the conductor bars 14 within the cast aluminum slots 8 of the all-cast aluminum rotor core, reducing the conductor length in the magnetic barrier slots, preventing eddy current losses, and thus improving the overall efficiency of the motor. However, the thickness L2 of the second core lamination 4 cannot be too large; excessive thickness will also generate eddy currents and lead to losses. Figure 6 The comparison chart showing the thickness of the second core lamination 4 and its relation to motor performance reveals that as the thickness L2 of the second core lamination 4 increases, the motor efficiency first rises and then falls. Therefore, it is crucial to determine the appropriate thickness of L2. The chart also shows that the efficiency is higher when the number of second core laminations is between 3 and 5, reaching its peak when the number is 4. In one embodiment, the thickness of a single second core lamination 4 is 1 mm.

[0036] In this embodiment of the motor rotor, the outer cast aluminum groove of the D-axis extends through the entire axial direction of the rotor core, resulting in a larger outer cast aluminum groove, stronger starting capability, and the ability to reduce eddy current losses by utilizing the structure of the second core segment 2. Therefore, the motor efficiency is increased by about three percent compared to the prior art. The aforementioned D-axis cast aluminum groove includes a first outer cast aluminum groove 7, an inner cast aluminum groove 8, and a second outer cast aluminum groove 9.

[0037] In one embodiment, the first outer cast aluminum groove 7, the inner cast aluminum groove 8, and the second outer cast aluminum groove 9 are filled with conductive but non-magnetic material to form a conductor bar 14, and end rings 15 are formed at both ends of the rotor core. The end rings 15 are connected to the conductor bar 14 to form a short-circuit ring.

[0038] In one embodiment, the end ring 15 is circular, with its inner diameter being greater than or equal to the diameter of the shaft hole of the rotor core, and its outer diameter being less than or equal to the outer diameter of the rotor core.

[0039] In this embodiment, the rotor core has large aluminum end rings 15 at both ends. The outer diameter of the end rings is slightly smaller than or equal to the outer diameter of the rotor core, and the inner diameter of the end rings 15 is slightly larger than or equal to the diameter of the shaft hole of the rotor core, so that the end rings 15 can form a solid structure. Since all the magnetic barrier slots are made of cast aluminum, there is no need for tooling to support the air slots, and the end rings can be designed to be as large as possible. Therefore, large frustum-shaped end rings can be formed at both ends of the rotor to ensure sufficient cast aluminum. The end rings 15 at both ends are connected by guide bars 14 in the magnetic barrier slots to form a passage and ensure the starting performance of the motor.

[0040] In one embodiment, the number of pole pairs P of the motor rotor is 2, the rotor structure has strong performance, and it is manufactured by a full aluminum casting process. During the production process, there is no need to consider the position of the aluminum casting tooling, which facilitates the implementation of aluminum casting and reduces manufacturing costs and difficulties.

[0041] According to an embodiment of this application, a self-starting synchronous reluctance motor includes a motor rotor, which is the motor rotor described above.

[0042] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0043] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A motor rotor, characterized in that, The rotor core includes a first core segment (1) at both ends and a second core segment (2) in the middle. The first core segment (1) is formed by stacking first core laminations (3), and the second core segment (2) is formed by stacking second core laminations (4). In a cross section perpendicular to the central axis of the rotor core, the first core lamination (3) includes a first D-axis magnetic barrier groove (5) extending along the D-axis direction. Each first D-axis magnetic barrier groove (5) includes a first outer cast aluminum groove (7) at both ends and an inner cast aluminum groove (8) in the middle. The second core lamination (4) includes a second D-axis magnetic barrier groove (6) extending along the D-axis direction. Each second D-axis magnetic barrier groove (6) includes a second outer cast aluminum groove (9) at both ends. The second outer cast aluminum grooves (9) at both ends are separated by a flat plate isolation layer (10). The flat plate isolation layer (10) is provided corresponding to the inner cast aluminum groove (8). The rotor core includes three first core segments (1) and two second core segments (2). The first core segments (1) and the second core segments (2) are staggered. The second core laminations (4) are stacked in the rotor core and cut the guide bars (14) in the inner cast aluminum groove (8). The axial height of the two first core segments (1) located at both ends is L1, the axial height of the first core segment (1) located between the two second core segments (2) is L3, the axial height of each second core segment (2) is L2, and the axial height of the rotor core is L. L1≥1 / 3L, L2<L3≤1 / 3L, L2>0.

2. The motor rotor according to claim 1, characterized in that, The first external aluminum casting groove (7) and the second external aluminum casting groove (9) have the same structure and the same position.

3. The motor rotor according to claim 1, characterized in that, The first outer cast aluminum groove (7) and the inner cast aluminum groove (8) are separated by an inner magnetic bridge (11).

4. The motor rotor according to claim 1, characterized in that, The rotor core has a Q-axis magnetic barrier groove (13) on the outermost side in the Q-axis direction.

5. The motor rotor according to claim 4, characterized in that, The outer periphery of the Q-axis magnetic barrier groove (13), the first D-axis magnetic barrier groove (5) and the second D-axis magnetic barrier groove (6) is provided with an outer magnetic bridge (12).

6. The motor rotor according to claim 1, characterized in that, The rotor core includes two first core segments (1) and one second core segment (2). The axial height of the second core segment (2) is L2, and the thickness of a single second core lamination (4) is δ, where δ≤L2.

7. The motor rotor according to claim 1, characterized in that, The first outer cast aluminum groove (7), the inner cast aluminum groove (8) and the second outer cast aluminum groove (9) are filled with conductive and non-magnetic materials to form a guide bar (14). The rotor core has end rings (15) at both ends, and the end rings (15) are connected to the guide bar (14) to form a short-circuit ring.

8. The motor rotor according to claim 7, characterized in that, The end ring (15) is circular, and the inner diameter of the end ring (15) is greater than or equal to the diameter of the shaft hole of the rotor core, and the outer diameter of the end ring (15) is less than or equal to the outer diameter of the rotor core.

9. A self-starting synchronous reluctance motor, comprising a motor rotor, characterized in that, The motor rotor is the motor rotor according to any one of claims 1 to 8.

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