Rotor assembly and self-starting permanent magnet synchronous reluctance electric motor

Abstract

The present application provides a rotor assembly and a self-starting permanent magnet synchronous reluctance electric motor. The rotor assembly includes a rotor core 1, and in a cross section of the rotor core 1, the rotor core 1 includes slit grooves 2, a q-axis squirrel-cage groove 41, and permanent magnets 3, the q-axis squirrel-cage grooves 41 are provided at both ends of the slit grooves 2, the permanent magnets 3 are arranged in the slit grooves 2, at least the permanent magnets 3 located in the innermost layer in the d-axis direction are arranged asymmetrically with respect to the d-axis, and the offset direction of the permanent magnets 3 located in the innermost layer with respect to the d-axis is the same as the rotation direction of the rotor assembly.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202110102655.X, entitled "ROTOR ASSEMBLY AND SELF-STARTING PERMANENT MAGNET SYNCHRONOUS RELUCTANCE MOTOR", filed on January 26, 2021, and the entire content thereof is incorporated herein by reference.

[0002] This application relates to the technical field of motors, and more particularly, to a rotor assembly and a self-starting permanent magnet synchronous reluctance motor.

Background Art

[0006] Therefore, the technical problem to be solved in this application is to provide a rotor assembly and a self-starting permanent magnet synchronous reluctance motor that allows more of the magnetic flux of the permanent magnets to flow to one side in the rotational direction of the rotor assembly, thereby improving the utilization rate of the permanent magnets and improving motor efficiency. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a rotor assembly including a rotor core, wherein in cross-section the rotor core comprises a slit groove, a q-axis squirrel cage groove, and permanent magnets, the q-axis squirrel cage groove being located at both ends of the slit groove, the permanent magnets being located within the slit groove, the permanent magnets located in the innermost layer in the d-axis direction being at least asymmetrically positioned with respect to the d-axis, and the offset direction of the permanent magnets located in the innermost layer with respect to the d-axis coinciding with the rotation direction of the rotor assembly.

[0008] In some embodiments, at least two layers of permanent magnets are arranged radially, and in two adjacent layers of permanent magnets, the portion of the permanent magnet located in the inner layer on the rear side of the d-axis occupies a central angle a1 with respect to the center of the rotor core, and the portion of the permanent magnet located in the outer layer on the rear side of the d-axis occupies a central angle a2 with respect to the center of the rotor core, where a1 ≤ a2. The front side of the d-axis refers to the side of the d-axis that is in the same direction as the rotation of the rotor assembly, and the rear side of the d-axis refers to the side of the d-axis opposite to the direction of rotation of the rotor assembly.

[0009] In some embodiments, the rotor assembly has a two-pole rotor structure.

[0010] In some embodiments, each layer of permanent magnets forms a structure that protrudes radially outward, and each layer of permanent magnets includes one or more arc-shaped or rectangular permanent magnets.

[0011] In some embodiments, the width of the permeable channel between adjacent q-axis cage grooves is greater than the minimum width of the permeable channel between slit grooves in the same layer.

[0012] In some embodiments, the rotor core also includes independent squirrel-cage grooves, where, under like polarity, the q-axis squirrel-cage grooves and independent squirrel-cage grooves are alternately arranged in the circumferential direction, and the total width of the permeable channels on both sides of the independent squirrel-cage grooves is greater than the minimum width of the permeable channels.

[0013] In some embodiments, the magnetic permeable channel is formed between adjacent slit grooves, and the width of the magnetic permeable channel decreases in the direction closer to the d-axis, and / or the magnetic permeable channel is formed between adjacent slit grooves, and the minimum width of the magnetic permeable channel is greater than twice the minimum width of the slit groove located in the inner layer adjacent to the magnetic permeable channel.

[0014] In some embodiments, the rotor core also comprises independent cage grooves, where, under like polarity, the q-axis cage grooves and independent cage grooves are alternately arranged in the circumferential direction, the extension direction of the q-axis cage grooves and independent cage grooves is parallel to the q-axis, and the q-axis cage grooves and independent cage grooves are distributed symmetrically with respect to the q-axis or d-axis.

[0015] In some embodiments, the extended length of the q-axis cage groove is longer than twice the width of the q-axis cage groove, and / or the extended length of the independent cage groove is longer than twice the width of the independent cage groove.

[0016] In some embodiments, the rotor core further comprises a d-axis squirrel cage groove, which is located on a specific side of the outermost permanent magnet in the radial direction of the d-axis, closer to the rotor's outer circle.

[0017] In some embodiments, multiple d-axis cage grooves are arranged and distributed symmetrically with respect to the d-axis or q-axis, and / or the d-axis cage grooves extend in the direction of the d-axis.

[0018] In some embodiments, the slit groove includes an arc-shaped portion and a straight portion, the arc-shaped portion protruding radially outward, the straight portion located at both ends of the arc-shaped portion, and the permanent magnets are installed in the arc-shaped portion and conform to the shape of the arc-shaped portion.

[0019] In some embodiments, a slit groove and corresponding q-axis cage grooves at both ends are combined to form a magnetic barrier layer, and the two magnetic barrier layers are arranged at least radially around the rotor core.

[0020] In some embodiments, the rotor core also comprises independent cage grooves, and under like poles, the q-axis cage grooves and independent cage grooves are arranged alternately in the circumferential direction, with at least certain edges of at least some of the specific ends of the q-axis cage grooves near the rotor outer circle having cut edges, and / or at least certain edges of at least some of the specific ends of the independent cage grooves near the rotor outer circle having cut edges.

[0021] In some embodiments, the rotor core also comprises independent cage grooves, where, under like polarity, the q-axis cage grooves and independent cage grooves are arranged alternately in the circumferential direction, the width of the magnetic bridge between the independent cage grooves and the rotor outer circle is L61, and the width of the magnetic bridge between the q-axis cage grooves and the rotor outer circle is L62, where L61 > L62, and / or, the rotor core also comprises d-axis cage grooves, where the d-axis cage grooves are located on a specific side of the rotor outer circle closer to the radially outermost permanent magnet in the d-axis direction, the width of the magnetic bridge between the d-axis cage grooves and the rotor outer circle is L63, and the width of the magnetic bridge between the q-axis cage grooves and the rotor outer circle is L62, where L63 > L62.

[0022] In some embodiments, the rotor core further includes an independent cage-shaped groove and a d-axis cage-shaped groove. The total area of the cage-shaped grooves formed by the q-axis cage-shaped groove, the d-axis cage-shaped groove, and the independent cage-shaped groove is S1. The total area of the cage-shaped grooves and the slit grooves is S, and S1 ≥ 40%S.

[0023] In some embodiments, the rotor core further includes an independent cage-shaped groove and a d-axis cage-shaped groove. The q-axis cage-shaped groove, the d-axis cage-shaped groove, and the independent cage-shaped groove are filled with a conductive and non-magnetic material. Both ends of the rotor core are provided with end rings. The q-axis cage-shaped groove, the d-axis cage-shaped groove, and the independent cage-shaped groove are short-circuited through the end rings to form a cage structure.

[0024] In some embodiments, both ends of the rotor core are provided with non-magnetic baffles, and the non-magnetic baffles are arranged to shield the permanent magnets.

[0025] According to another aspect of the present application, a self-starting permanent magnet synchronous reluctance motor is provided, including a stator and a rotor assembly. The rotor assembly is the above-mentioned rotor assembly.

[0026] In some embodiments, the width of the magnetic bridge between the q-axis cage-shaped groove and the outer circumference of the rotor is L62, where 0.5σ ≤ L62 ≤ 1.5σ, and σ is the radial width of the air gap between the stator and the rotor core.

[0027] The rotor assembly according to the present application includes a rotor core. In the cross-section of the rotor core, the rotor core includes a slit groove, a q-axis cage-shaped groove, and a permanent magnet. The q-axis cage-shaped groove is disposed at both ends of the slit groove, and the permanent magnet is disposed in the slit groove. The permanent magnet located in the innermost layer in the d-axis direction is disposed at least asymmetrically with respect to the d-axis, and the offset direction of the permanent magnet located in the innermost layer with respect to the d-axis coincides with the rotation direction of the rotor assembly. With such a structure, the flow direction of the magnetic flux generated by the offset permanent magnet is directed more towards the magnetic flux direction of the q-axis of the rotor, and more q-axis magnets are provided. Since the magnetic flux of the permanent magnet is offset towards the rear side in the rotation direction of the rotor assembly under the rotation of the rotor assembly, the problem of unbalanced magnetic flux of the permanent magnet is avoided. As a result, the magnetic flux located on the front side of the d-axis is more consistent with the magnetic flux located on the rear side of the d-axis, the utilization efficiency of the permanent magnet is improved, and the motor efficiency is improved.

Brief Description of the Drawings

[0028] [Figure 1] It is a schematic structural diagram of a rotor assembly according to an embodiment of the present application. [Figure 2] It is a schematic enlarged partial structural diagram of a rotor assembly according to an embodiment of the present application. [Figure 3] It is a schematic structural diagram of a rotor assembly according to an embodiment of the present application. [Figure 4] It is an axial view of a rotor assembly according to an embodiment of the present application. [Figure 5] It is a schematic structural diagram of an impermeable baffle of a rotor assembly according to an embodiment of the present application. [Figure 6] It is an axial view of a rotor assembly according to an embodiment of the present application. [Figure 7] It is a comparison diagram of torque curves between a motor according to an embodiment of the present application and a motor of related art.

Modes for Carrying Out the Invention

[0029] Referring to Figures 1 to 7 in combination, according to one embodiment of the present invention, the rotor assembly includes a rotor core 1. In a cross-section of the rotor core 1, the rotor core 1 comprises a shaft hole 5, a slit groove 2, a q-axis squirrel cage groove 41, and permanent magnets 3. The q-axis squirrel cage groove 41 is located at both ends of the slit groove 2, and the permanent magnets 3 are located within the slit groove 2. The permanent magnets 3 located in the innermost layer in the d-axis direction are arranged at least asymmetrically with respect to the d-axis, and the offset direction of the permanent magnets 3 located in the innermost layer with respect to the d-axis coincides with the rotation direction of the rotor assembly.

[0030] This structure ensures that the direction of the magnetic flux flow generated by the offset permanent magnets is more aligned with the magnetic flux direction of the rotor's q-axis, allowing for more q-axis magnets. This avoids the problem of unbalanced magnetic flux from the permanent magnets, which occurs when the magnetic flux of the permanent magnets is offset towards the rear of the rotor assembly's rotation direction during the rotor assembly's rotation. As a result, the magnetic flux located on the front of the d-axis better matches the magnetic flux located on the rear of the d-axis, improving the utilization efficiency of the permanent magnets and thus improving motor efficiency. The front of the d-axis refers to the side of the d-axis that is in the same direction as the rotor assembly's rotation direction, and the rear of the d-axis refers to the side of the d-axis opposite to the rotor assembly's rotation direction.

[0031] In this embodiment, the offset direction of the innermost permanent magnet 3 relative to the d-axis coincides with the rotation direction of the rotor assembly. This means that, for the innermost permanent magnet 3, the amount of permanent magnet used on the front side of the d-axis is greater than the amount of permanent magnet used on the rear side of the d-axis. Specifically, with respect to the permanent magnet 3 relative to the d-axis, the length of the permanent magnet located on the front side of the d-axis is longer than the length of the permanent magnet located on the rear side of the d-axis, or the thickness of the permanent magnet located on the front side of the d-axis is greater than the thickness of the permanent magnet located on the rear side of the d-axis. The purpose of this is to make the magnetic flux of the permanent magnet 3 on the front side of the d-axis greater than the magnetic flux of the permanent magnet 3 on the rear side of the d-axis when the rotor assembly is not operating. As a result, the offset of the magnetic flux caused by the rotation of the rotor assembly is reduced when the rotor assembly rotates, the magnetic flux on both sides of the d-axis is made as equal as possible, the utilization rate of the permanent magnets is improved, and the motor efficiency is improved.

[0032] As shown in Figure 2, at least two layers of the permanent magnet 3 are arranged radially. In two adjacent layers of the permanent magnet 3, the portion of the permanent magnet 3 located in the inner layer behind the d-axis occupies a central angle a1 with respect to the center of the rotor core 1, and the portion of the permanent magnet 3 located in the outer layer behind the d-axis occupies a central angle a2 with respect to the center of the rotor core, where a1 ≤ a2. Therefore, more q-axis flux linkage can be generated by the inner layer permanent magnet 3, further improving motor efficiency and allowing for more full utilization of the permanent magnet 3.

[0033] Taking the three layers of radially arranged permanent magnets 3 as one example, the portion of permanent magnet 3 located in the outermost layer behind the d-axis occupies a central angle a3 with respect to the center of the rotor core 1, the portion of permanent magnet 3 located in the middle layer behind the d-axis occupies a central angle a2 with respect to the center of the rotor core 1, and the portion of permanent magnet 3 located in the innermost layer behind the d-axis occupies a central angle a1, where a1 ≤ a2 ≤ a3. The permanent magnets 3 consider the d-axis as a boundary line. In the rotational direction of the rotor assembly, the connection line between the endpoint of one end of the permanent magnet 3 located behind the d-axis and the center of the rotor core 1 is considered the first connection line, and the angle formed between the first connection line and the d-axis is the central angle occupied by the portion of permanent magnet 3 behind the d-axis with respect to the center of the rotor core 1.

[0034] In this embodiment, the ratio by which the permanent magnet 3 is offset toward the front of the d-axis in the radially outward direction becomes smaller and smaller.

[0035] In one embodiment, the permanent magnets 3 located in the intermediate layer and the innermost layer are both offset toward the front of the d-axis, while the permanent magnet 3 located in the radially outermost layer is symmetrical with respect to the d-axis.

[0036] In some embodiments, the rotor assembly has a two-pole rotor structure.

[0037] In this motor, the force moment generated by the magnetic fields of the permanent magnets located in the inner layers and the stator is larger and has a greater impact on the motor's performance. Therefore, in order to ensure that the motor's performance is maximized and the structure is optimized to the fullest extent, it is necessary to ensure the maximum possible offset of the permanent magnets located in the innermost layer.

[0038] In some embodiments, when the three layers of permanent magnets 3 are arranged radially, only the permanent magnet 3 located in the innermost layer in the radial direction may be offset, and the permanent magnets 3 located in the intermediate and outermost layers are symmetrical with respect to the d-axis.

[0039] Each layer of the permanent magnet 3 forms a structure that protrudes radially outward, and each layer of the permanent magnet 3 includes one or more arc-shaped or rectangular permanent magnets.

[0040] When a layer of permanent magnets 3 contains multiple permanent magnets, the offset can be achieved by offsetting a portion of the permanent magnets 3. As shown in Figure 3, in the innermost layer, one permanent magnet 3 is located in front of the d-axis, while another permanent magnet 3 is symmetrical with respect to the d-axis, thereby enabling the offset of the permanent magnets 3 in front of the d-axis. In this structure, since the permanent magnets 3 employ a block structure, the design is more flexible, and the installation position of the permanent magnets 3 can be set more rationally.

[0041] In some embodiments, the width of the magnetic permeable channel between adjacent q-axis cage grooves 41 is greater than the minimum width of the magnetic permeable channel between slit grooves 2 in the same layer.

[0042] The rotor core 1 also includes independent squirrel-cage grooves 42. Under the same polarity, the q-axis squirrel-cage grooves 41 and the independent squirrel-cage grooves 42 are arranged alternately in the circumferential direction, and the total width of the permeable channels on both sides of the independent squirrel-cage grooves 42 is greater than the minimum width of the permeable channels.

[0043] As shown in Figure 1, taking three layers of radially arranged permanent magnets 3 as one example, the independent cage grooves 42 are located between adjacent q-axis cage grooves 41. The widths of the permeable channels on both sides of the independent cage grooves 42 located in the inner layer are L31 and L32, and the minimum width of the permeable channels located in the inner layer is L3. The widths of the permeable channels on both sides of the independent cage grooves 42 located in the outer layer are L41 and L42, and the minimum width of the permeable channels located in the outer layer is L4. Therefore, L31+L32>L3 and L41+L42>L4.

[0044] The magnetic permeable channels are formed between adjacent slip grooves 2, and the width of the magnetic permeable channels decreases in the direction closer to the d-axis.

[0045] The magnetic permeable channels are formed between adjacent slip grooves 2, and the minimum width of the magnetic permeable channels is greater than twice the minimum width of the slit grooves 2 located in the inner layer adjacent to the magnetic permeable channels.

[0046] As shown in Figures 1 and 3, taking three layers of radially arranged permanent magnets 3 as one example, the minimum width of the permeable channel in the inner layer is L3, the minimum width of the slit groove 2 adjacent to the permeable channel in the inner layer and located in the inner layer is L1, the minimum width of the permeable channel in the outer layer is L4, and the minimum width of the slit groove 2 adjacent to the permeable channel in the outer layer and located in the inner layer is L2, where L3 > 2 × L1 and L4 > 2 × L2. With the above design, saturation of the permeable channel between the squirrel-cage groove 4 or the slit groove 2 can be avoided, the influence of the q-axis magnetic flux on the squirrel-cage groove 4 is reduced, and the output torque and efficiency of the motor are improved.

[0047] The rotor core 1 also includes independent squirrel-cage grooves 42. Under the same polarity, the q-axis squirrel-cage grooves 41 and independent squirrel-cage grooves 42 are alternately arranged in the circumferential direction, and the extension direction of the q-axis squirrel-cage grooves 41 and independent squirrel-cage grooves 42 is parallel to the q-axis. As a result, the q-axis squirrel-cage grooves 41 coincide with the slit grooves 2, allowing for the formation of smooth magnetic permeability channels in the rotor. The q-axis squirrel-cage grooves 41 and independent squirrel-cage grooves 42 are distributed symmetrically with respect to the q-axis or the d-axis.

[0048] The extended length of the q-axis cage groove 41 is longer than twice the width of the q-axis cage groove 41, and / or the extended length of the independent cage groove 42 is longer than twice the width of the independent cage groove 42.

[0049] As shown in Figure 3, taking an independent squirrel-cage groove 42 as one example, its elongation length in the q-axis direction is L52, its width is L51, and L52 > 2 × L51. Under conditions of an unsaturated magnetic field, the squirrel-cage groove adopts an elongated structure to accommodate more squirrel-cage grooves, thereby improving the motor's starting performance. By making the squirrel-cage groove longer, the area of ​​the squirrel-cage groove can be increased, reducing the resistance of the squirrel-cage groove, further improving starting performance and ensuring the motor's synchronous starting capability.

[0050] The rotor core 1 also includes a d-axis squirrel cage groove 43, which is located on a specific side of the rotor outer circle near the radially outermost permanent magnet 3 in the d-axis direction.

[0051] There are multiple d-axis cage grooves 43 distributed symmetrically with respect to the d-axis or q-axis, and / or the d-axis cage grooves 43 extend in the direction of the d-axis.

[0052] The d-axis squirrel cage groove 43 extends in a direction parallel to the d-axis, thus avoiding the magnetic saturation phenomenon caused by the gradual decrease in the width of the d-axis squirrel cage groove 43 in the direction closer to the rotor's outer circle. At the same time, multiple permeable channels are formed between the d-axis squirrel cage groove 43, which facilitates the passage of magnetic field lines and improves the motor's output.

[0053] As shown in Figure 1, in some embodiments, the slit groove 2 includes an arc-shaped portion 21 and a straight portion 22. The arc-shaped portion 21 protrudes radially outward, and the straight portion 22 is located at both ends of the arc-shaped portion 21. The permanent magnets 3 are installed in the arc-shaped portion 21 and conform to the shape of the arc-shaped portion 21. Each layer of the permanent magnets 3 contains one or more permanent magnets, and the rotor space can be effectively utilized to arrange the slit groove 2 and the permanent magnets 3, improving the material utilization rate of the motor.

[0054] In one embodiment, each layer of the slit groove 2 can also be formed by combining multiple straight sections, and the overall shape of each layer of the permanent magnet 3 protrudes outward in the rotational direction along the d-axis.

[0055] The slit groove 2 and the corresponding q-axis cage grooves 41 at both ends of the slit groove 2 are combined to form a magnetic barrier layer, and the number of radial magnetic barrier layers on the rotor core is at least two or more, so that a certain number of magnetic barriers are formed on the rotor core 1, a certain salient pole difference is ensured, the reluctance torque of the motor can be increased, and the output capacity and efficiency of the motor can be improved.

[0056] The rotor core 1 also includes independent cage grooves 42. Under the same pole, the q-axis cage grooves 41 and the independent cage grooves 42 are arranged alternately in the circumferential direction, and at least certain edges of at least some of the specific ends of the q-axis cage grooves 41 near the rotor outer circle are provided with cut edges 7.

[0057] At least certain edges of certain ends of at least a portion of the independent squirrel-cage grooves 42 near the rotor's outer circle are provided with cut edges 7. The cut edges 7 can effectively reduce abrupt changes in inductance, resulting in a gradual transition of magnetic flux, reduced magnetic field fluctuations, and reduced motor harmonics and torque ripple.

[0058] In one embodiment, both ends of specific ends of the q-axis squirrel cage groove 41 and independent squirrel cage groove 42 near the rotor outer circle are provided with cut edges 7.

[0059] The rotor core 1 also includes independent squirrel-cage grooves 42. Under the same polarity, the q-axis squirrel-cage grooves 41 and the independent squirrel-cage grooves 42 are arranged alternately in the circumferential direction. The width of the magnetic bridge 6 between the independent squirrel-cage grooves 42 and the rotor outer circle is L61, and the width of the magnetic bridge 6 between the q-axis squirrel-cage grooves 41 and the rotor outer circle is L62, where L61 > L62. As a result, the width of the magnetic bridge 6 between the independent squirrel-cage grooves 42 that do not coincide with and are not connected to the permanent magnets 3 and the rotor outer circle can be appropriately widened to reduce motor harmonics and improve motor starting performance.

[0060] In one embodiment, the rotor core 1 also includes a d-axis cage-shaped groove 43, and the d-axis cage-shaped groove 43 is located on a specific side of the outermost permanent magnet 3 in the d-axis direction, closer to the rotor outer circle. The width of the magnetic bridge 6 between the d-axis cage-shaped groove 43 and the rotor outer circle is L63, and the width of the magnetic bridge 6 between the q-axis cage-shaped groove 41 and the rotor outer circle is L62, where L63 > L62.

[0061] The rotor core 1 also includes an independent cage-shaped groove 42 and a d-axis cage-shaped groove 43. The total area of the cage-shaped groove 4 formed by the q-axis cage-shaped groove 41, the d-axis cage-shaped groove 43, and the independent cage-shaped groove 42 is S1, the total area of the cage-shaped groove 4 and the slit groove 2 is S, and S1 ≥ 40%S. In some embodiments, 0.5×S < S1 < 0.7×S, which can ensure a certain area and improve the synchronous ability of the motor.

[0062] As shown in FIG. 6, the rotor core 1 also includes an independent cage-shaped groove 42 and a d-axis cage-shaped groove 43. The q-axis cage-shaped groove 41, the d-axis cage-shaped groove 43, and the independent cage-shaped groove 42 are arranged together in the circumferential direction of the rotor core 1 to form a cage-shaped groove 4, and the cage-shaped groove 4 is filled with a conductive and non-magnetic material such as aluminum or an aluminum alloy. Both ends of the rotor core 1 are provided with end rings 8, and the q-axis cage-shaped groove 41, the d-axis cage-shaped groove 43, and the independent cage-shaped groove 42 are short-circuited through the end rings 8 to form a cage-shaped structure. The material of the end ring is the same as the filling material in the cage-shaped groove 4. The self-shorted cage-shaped structure provides an asynchronous torque at the starting stage of the motor to realize the self-starting of the motor. The rotor multi-layer permanent magnetic barrier structure formed by the slit groove 2, the cage-shaped groove 4, and the permanent magnet 3 provides a permanent magnet torque and a reluctance torque for the motor to realize the synchronous operation of the motor.

[0063] Both ends of the rotor core 1 are equipped with impermeable baffles 9, which can shield the permanent magnets 3 but cannot shield all of the slit grooves 2. The impermeable baffles 9 can fix both ends of the permanent magnets 3 in the axial direction of the rotor core 1, and the unshielded portions of the slit grooves 2 can form axial through holes in the rotor core 1, which helps air or coolant to flow, improve heat dissipation of the rotor, and improve motor efficiency.

[0064] The rotor core 1 also has rivet holes, and the rotor assembly is formed by strongly compressing the impermeable baffles 9 at both ends of the rotor core 1 in the axial direction via rivets 10.

[0065] The shaft hole 5 may be circular, elliptical, or rectangular.

[0066] By referring in conjunction with Figure 7, which is a comparative diagram of the torque curves of the motor of the embodiment of the present application and motors of related technologies, it can be understood from Figure 7 that, under the same stator and current, the torque of the motor employing the solution of the embodiment of the present application is improved, the torque peak and torque ripple values ​​are reduced, and a better effect can be achieved.

[0067] According to one embodiment of the present invention, a self-starting permanent magnet synchronous reluctance motor includes a stator and a rotor assembly, wherein the rotor assembly is the rotor assembly described above.

[0068] In one embodiment, the width of the magnetic bridge 6 between the q-axis squirrel cage groove 41 and the rotor outer circle is L62, where 0.5σ ≤ L62 ≤ 1.5σ, and σ is the radial width of the air gap between the stator and the rotor core 1. As a result, the magnetic bridge 6 between the q-axis squirrel cage groove 41 and the rotor outer circle can have an appropriate width, and magnetic leakage can be reduced as much as possible while ensuring the mechanical strength of the rotor assembly.

[0069] Those skilled in the art will readily understand that the various preferred methods described above can be freely combined and superimposed without contradiction.

[0070] The foregoing describes only preferred embodiments of the present application and is not intended to limit it. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application should be included within the scope of protection. The foregoing describes only preferred embodiments of the present application. Those skilled in the art should point out that several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be considered within the scope of protection. [Explanation of symbols]

[0071] 1 Rotor core 2 Slit grooves 21 Arc-shaped portion 22 Straight section 3 Permanent magnets 4 Cage-shaped groove 41 Q-axis cage groove 42 Independent cage-type grooves 43 d-axis cage groove 5 shaft holes 6. Magnetic Bridge 7. Cutting edge 8 End Rings 9. Magnetic-impermeable baffle 10 rivets

Claims

1. A rotor assembly comprising a rotor core (1), wherein in a cross-section of the rotor core (1), the rotor core (1) comprises a slit groove (2), a q-axis cage groove (41), and permanent magnets (3), the q-axis cage groove (41) being located at both ends of the slit groove (2), the permanent magnets (3) being located within the slit groove (2), the permanent magnets (3) located in the innermost layer in the d-axis direction being at least asymmetrically arranged with respect to the d-axis, and the offset direction of the permanent magnets (3) located in the innermost layer with respect to the d-axis being consistent with the rotation direction of the rotor assembly. The width of the magnetic permeable channel between adjacent q-axis cage grooves (41) is greater than the minimum width of the magnetic permeable channel between the slit grooves (2) in the same layer. The rotor assembly further comprises a rotor core (1) with independent cage grooves (42), wherein, under the same pole, the q-axis cage grooves (41) and the independent cage grooves (42) are alternately arranged in the circumferential direction, and the total width of the permeable channels at both ends of the independent cage grooves (42) is greater than the minimum width of the permeable channels.

2. At least two layers of the permanent magnet (3) are arranged radially, and in the two adjacent layers of the permanent magnet (3), the portion of the permanent magnet (3) located in the inner layer on the rear side of the d-axis has a central angle a1 with respect to the center of the rotor core (1), and the portion of the permanent magnet (3) located in the outer layer on the rear side of the d-axis has a central angle a2 with respect to the center of the rotor core (1), where a1 ≤ a2. The rotor assembly according to claim 1, wherein the front side of the d-axis points to the side of the d-axis that is the same as the rotation direction of the rotor assembly, and the rear side of the d-axis points to the side of the d-axis opposite to the rotation direction of the rotor assembly.

3. The rotor assembly according to claim 1, wherein the rotor assembly has a two-pole rotor structure.

4. The rotor assembly according to claim 1, wherein each layer of permanent magnets (3) forms a structure that protrudes radially outward, and each layer of permanent magnets (3) comprises one or more arc-shaped or rectangular permanent magnets (3).

5. The rotor assembly according to claim 1, wherein the permeable channel is formed between adjacent slit grooves (2), the width of the permeable channel decreases in the direction closer to the d-axis, and / or the permeable channel is formed between adjacent slit grooves (2), the minimum width of the permeable channel is greater than twice the minimum width of the slit groove (2) located in the inner layer adjacent to the permeable channel.

6. The rotor assembly according to claim 1, wherein the extension direction of the q-axis cage groove (41) and the independent cage groove (42) is parallel to the q-axis, and the q-axis cage groove (41) and the independent cage groove (42) are distributed symmetrically with respect to the q-axis or the d-axis.

7. The rotor assembly according to claim 1, wherein the extended length of the q-axis cage groove (41) is longer than twice the width of the q-axis cage groove (41), and / or the extended length of the independent cage groove (42) is longer than twice the width of the independent cage groove (42).

8. The rotor assembly according to claim 1, wherein the rotor core (1) further comprises a d-axis squirrel cage groove (43), the d-axis squirrel cage groove (43) is located on the side of the outermost permanent magnet (3) in the radial direction in the d-axis direction that is closer to the outer circle of the rotor.

9. The rotor assembly according to claim 8, wherein a plurality of d-axis cage grooves (43) are arranged and distributed symmetrically with respect to the d-axis or the q-axis, and / or the d-axis cage grooves (43) extend in the direction of the d-axis.

10. The rotor assembly according to claim 1, wherein the slit groove (2) comprises an arc-shaped portion (21) and a straight portion (22), the arc-shaped portion (21) protruding radially outward, the straight portion (22) located at both ends of the arc-shaped portion (21), and the permanent magnet (3) is installed in the arc-shaped portion (21) and conforms to the shape of the arc-shaped portion (21).

11. The rotor assembly according to claim 1, wherein the slit groove (2) and the corresponding q-axis cage grooves (41) at both ends are combined to form a magnetic barrier layer, and the two magnetic barrier layers are arranged at least radially around the rotor core (1).

12. The rotor assembly according to claim 1, wherein at least a specific edge of at least a portion of a specific end of the q-axis squirrel cage groove (41) near the rotor outer circle is provided with a cut edge (7), and / or at least a specific edge of at least a portion of a specific end of the independent squirrel cage groove (42) near the rotor outer circle is provided with a cut edge (7).

13. The rotor assembly according to claim 1, wherein the width of the magnetic bridge (6) between the independent cage groove (42) and the rotor outer circle is L61, the width of the magnetic bridge (6) between the q-axis cage groove (41) and the rotor outer circle is L62, where L61 > L62, and / or the rotor core (1) also comprises a d-axis cage groove (43), the d-axis cage groove (43) located on a specific side of the radially outermost permanent magnet (3) in the d-axis direction, closer to the rotor outer circle, the width of the magnetic bridge (6) between the d-axis cage groove (43) and the rotor outer circle is L63, and the width of the magnetic bridge (6) between the q-axis cage groove (41) and the rotor outer circle is L62, where L63 > L62.

14. The rotor assembly according to claim 1, wherein the rotor core (1) further comprises a d-axis cage groove (43), the total area of ​​the cage groove (4) formed by the q-axis cage groove (41), the d-axis cage groove (43), and the independent cage groove (42) is S1, the total area of ​​the cage groove (4) and the slit groove (2) is S, and S1 ≥ 40%S.

15. The rotor assembly according to claim 1, wherein the rotor core (1) further comprises a d-axis squirrel cage groove (43), the q-axis squirrel cage groove (41), the d-axis squirrel cage groove (43), and the independent squirrel cage groove (42) are filled with a conductive and non-magnetic material, both ends of the rotor core (1) are provided with end rings (8), and the q-axis squirrel cage groove (41), the d-axis squirrel cage groove (43), and the independent squirrel cage groove (42) are short-circuited via the end rings (8) to form a squirrel cage structure.

16. The rotor assembly according to claim 1, wherein both ends of the rotor core (1) are provided with magnetically impermeable baffles (9), and the magnetically impermeable baffles (9) are arranged to shield the permanent magnets (3).

17. A self-starting permanent magnet synchronous reluctance motor comprising a stator and a rotor assembly, wherein the rotor assembly is the rotor assembly described in any one of claims 1 to 16.

18. The width of the magnetic bridge (6) between the q-axis squirrel cage groove (41) and the rotor outer circle is L62, where 0.5σ ≤ L62 ≤ 1.5σ, and σ is the radial width of the air gap between the stator and the rotor core (1), as described in claim 17.

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