Rotor assembly and self-starting permanent magnet synchronous reluctance motor

Abstract

The present application provides a rotor assembly and a self-starting permanent magnet synchronous reluctance motor. The rotor assembly comprises a rotor core (1). On a cross section perpendicular to the central axis of the rotor core (1), the rotor core (1) is provided with an axial hole (6), a slit slot (2), a q-axis squirrel cage slot (3) and a permanent magnet (4). The q-axis squirrel cage slot (3) is provided at both ends of the slit slot (2). The permanent magnet (4) is installed at both ends of at least part of the slit slot (2). Two permanent magnets (4) located in the same slit slot (2) are arranged at intervals. According to the rotor assembly of the present application, the utilization rate of the rotor space can be increased. While utilizing the reluctance torque of the motor, the permanent magnet torque of the motor can be increased, the iron loss of the motor can be reduced, and the output and efficiency of the motor can be improved.

Description

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 26, 2021, with application number 2021101026526 and invention name “Rotor Assembly and Self-Starting Permanent Magnet Synchronous Reluctance Motor”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of motor technology, and in particular to a rotor assembly and a self-starting permanent magnet synchronous reluctance motor. Background Art

[0003] The self-starting permanent magnet-assisted synchronous reluctance motor combines the advantages of an asynchronous motor with those of a permanent magnet-assisted synchronous reluctance motor. It achieves self-starting through the asynchronous torque generated by the rotor bars and constant speed operation through the combination of permanent magnet torque and reluctance torque. Compared to asynchronous motors, it offers constant speed operation, low rotor losses, and high efficiency. Compared to asynchronous-start permanent magnet synchronous motors, it uses fewer permanent magnets and offers lower motor costs.

[0004] However, a magnetic barrier layer and a magnetic channel are set on the rotor of the self-starting permanent magnet assisted synchronous reluctance motor at the same time, and the widths of the two restrict each other. Whether the width of the magnetic barrier layer or the magnetic channel is too small, it will affect the motor efficiency and cause a high degree of saturation of the rotor core. Setting the magnetic barrier layer and permanent magnet at the same time will further increase the motor saturation, resulting in increased motor iron loss and reduced motor efficiency. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this application is to provide a rotor assembly and a self-starting permanent magnet synchronous reluctance motor, which can increase the utilization rate of the rotor space, increase the permanent magnet torque of the motor while utilizing the motor's reluctance torque, reduce the motor's iron loss, and improve the motor's output and efficiency.

[0006] In order to solve the above problems, the present application provides a rotor assembly, including a rotor core. In a cross section perpendicular to the central axis of the rotor core, the rotor core is provided with an axial hole, a slit slot, a q-axis squirrel cage slot and a permanent magnet, the q-axis squirrel cage slot is arranged at both ends of the slit slot, and the permanent magnet is installed at both ends of at least part of the slit slot, and the two permanent magnets located in the same slit slot are arranged at intervals.

[0007] Preferably, the slit groove includes an arc segment and a straight segment, and the straight segments are located at both ends of the arc segment.

[0008] Preferably, the width of the arc segment in the d-axis direction increases gradually in the direction away from the d-axis.

[0009] Preferably, the slit slots are at least two layers, the d-axis width of the slit slots increases from the middle to both ends, and the d-axis width of the magnetic conductive channels between adjacent slit slots increases from the middle to both ends.

[0010] Preferably, the slit slot includes a magnetic resistance section and a mounting section, the mounting section is located at both ends of the magnetic resistance section, the mounting section extends along the q-axis direction, the permanent magnet is mounted in the mounting section, and the magnetization direction of the permanent magnet is parallel to the d-axis.

[0011] Preferably, the permanent magnets are arranged in at least two layers, and along the radially inward direction of the d-axis, the lengths of the permanent magnets along the q-axis gradually increase.

[0012] Preferably, the permanent magnets are arranged in at least two layers, and the minimum distance between the permanent magnets and the d-axis decreases radially inward along the d-axis.

[0013] Preferably, the q-axis squirrel cage groove extends along the q-axis direction and is parallel to the q-axis.

[0014] Preferably, the width of the magnetic conductive channel between two adjacent q-axis cage slots is d1, and the width of the magnetic conductive channel between two slit slots corresponding to the two q-axis cage slots is d2, wherein d1≥d2.

[0015] Preferably, the slit slots and the permanent magnets are both multi-layered, and the number of layers of the slit slots is greater than or equal to the number of layers of the permanent magnets.

[0016] Preferably, when the number of layers of the slit slots is greater than the number of layers of the permanent magnets, the d-axis width of the slit slots where the permanent magnets are not installed increases in the direction away from the d-axis, and the slit slots where the permanent magnets are installed include arc segments and straight segments, the straight segments are located at both ends of the arc segments, and the permanent magnets are installed in the straight segments.

[0017] Preferably, along the radially outward direction of the d-axis, the curvature of the arc segment of the slit groove decreases, and the outer arc curvature of the slit grooves located in the same layer is smaller than the inner arc curvature.

[0018] Preferably, the rotor core is further provided with a d-axis squirrel cage slot, which is located on a side of the q-axis squirrel cage slot close to the d-axis.

[0019] Preferably, the d-axis squirrel cage slots extend along the circumferential direction of the rotor core.

[0020] Preferably, there is one d-axis cage slot under the same pole, and the d-axis cage slot is arranged on the d-axis; or, there are at least two d-axis cage slots under the same pole, and the at least two d-axis cage slots are arranged at intervals along the circumference of the rotor core.

[0021] Preferably, at the same pole, along the d-axis direction, the radial width of the d-axis squirrel cage slot is m1, the radial width of the slit slot located on the d-axis is m2, and the radial width between the outer circle of the shaft hole and the rotor outer circle of the rotor core is m3, where (m1+∑m2) / m3=0.3~0.5.

[0022] Preferably, the total area of ​​the q-axis cage slot and the d-axis cage slot is S1, and the total area of ​​the q-axis cage slot, the d-axis cage slot and the slit slot is S2, wherein S1 / S2=30% to 70%.

[0023] Preferably, in the cross section of the rotor core, the angle formed by the line connecting the circumferential ends of the d-axis squirrel cage slot and the central axis of the rotor core is α1, where 20°≤α1≤60°.

[0024] Preferably, the total area of ​​the d-axis squirrel cage slots under each pole is S3, and the maximum area of ​​a single q-axis squirrel cage slot is S4, where S3≥2S4.

[0025] Preferably, the q-axis cage slots and the d-axis cage slots are filled with conductive non-magnetic material, and end rings are provided at both ends of the rotor core. The q-axis cage slots and the d-axis cage slots are short-circuited through the end rings to form a cage structure.

[0026] Preferably, the width of the shaft hole on the d-axis is less than or equal to the width on the q-axis; and / or the rotor assembly is a two-pole structure.

[0027] According to another aspect of the present application, a self-starting permanent magnet synchronous reluctance motor is provided, comprising a stator and a rotor assembly, wherein the rotor assembly is the above-mentioned rotor assembly.

[0028] Preferably, when the slit slots and the permanent magnets are both multi-layered and the magnetization direction of the permanent magnets is parallel to the d-axis, the minimum thickness of each layer of permanent magnets along the magnetization direction is h, where 4σ≤h≤8.5σ, and σ is the radial width of the air gap between the stator and rotor cores.

[0029] Preferably, the width of the magnetic conductive channel between two q-axis squirrel cage slots adjacent to the q-axis is d3, and the width of the stator teeth is t, wherein d3>t.

[0030] Preferably, the minimum spacing between the q-axis squirrel cage slot and the slit slot in the same layer is h1, where 0.8σ≤h1≤2σ, and σ is the radial width of the air gap between the stator and rotor cores.

[0031] Preferably, the minimum spacing between the q-axis squirrel cage slot and the rotor outer circle of the rotor core is h2, wherein h2>σ, σ is the radial width of the air gap between the stator and the rotor core.

[0032] Preferably, when q-axis cage slots, slit slots, permanent magnets and d-axis cage slots are provided on the rotor core, the q-axis cage slots, slit slots and permanent magnets located on the same layer form a permanent magnet magnetic barrier layer, and / or, the q-axis cage slots and slit slots located on the same layer form a permanent magnet magnetic barrier layer, and / or, the d-axis cage slots located on the same layer form a permanent magnet magnetic barrier layer, the minimum distance between adjacent permanent magnet magnetic barrier layers is h3, and the minimum width of the permanent magnet magnetic barrier layer with a smaller width along the d-axis direction in the adjacent permanent magnet magnetic barrier layers in the d-axis direction is h4, where h3≥1.8h4.

[0033] The rotor assembly provided in this application includes a rotor core. The rotor core is provided with an axial hole, a slit slot, a q-axis squirrel cage slot, and a permanent magnet in its cross-section. The q-axis squirrel cage slot is provided at both ends of the slit slot. The permanent magnet is installed at both ends of at least a portion of the slit slot, and two permanent magnets located in the same slit slot are spaced apart. This rotor assembly arranges the permanent magnets at both ends of the slit slot. This arrangement allows for the rational use of rotor space for the arrangement of the permanent magnets, increasing the motor's permanent magnet torque while ensuring the motor's reluctance torque, improving the motor's output and efficiency, and enhancing the motor's power factor. Furthermore, the placement of the permanent magnets at both ends can reduce the motor's iron loss, further improving motor efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of a rotor assembly according to one embodiment of the present application;

[0035] Figure 2 This is a schematic structural diagram of a rotor assembly according to one embodiment of the present application;

[0036] Figure 3 A comparison diagram of torque curves of the motor according to the embodiment of the present application and the motor in the related art;

[0037] Figure 4 A comparison chart of iron loss between the motor according to the embodiment of the present application and the motor in the related art;

[0038] Figure 5 : is a curve showing the relationship between the output torque and (m1+∑m2) / m3 in the motor according to an embodiment of the present application;

[0039] Figure 6 : is a curve showing the relationship between the pull-in torque and S1 / S2 in the motor according to an embodiment of the present application;

[0040] Figure 7 is a curve showing the relationship between the pull-in torque and efficiency and α1 in the motor according to the embodiment of the present application;

[0041] Figure 8 The relationship between the speed and S3 during the motor starting process of the embodiment of the present application;

[0042] Figure 9 The relationship curve between the average magnetic flux density and efficiency of the permanent magnets of the motor according to the embodiment of the present application and h / σ is shown;

[0043] Figure 10 The relationship between the motor torque curve and d3 in the embodiment of the present application;

[0044] Figure 11 : is a curve showing the relationship between the magnetic leakage coefficient of the magnetic circuit between the q-axis squirrel cage slot and the slit slot and h1 / σ in an embodiment of the present application;

[0045] Figure 12 The relationship between the motor output torque and h3 in the embodiment of the present application;

[0046] Figure 13 This is the relationship between the motor iron loss and h3 in the embodiment of the present application.

[0047] The reference numerals indicate:

[0048] 1. Rotor core; 2. Slit slot; 3. Q-axis squirrel cage slot; 4. Permanent magnet; 5. D-axis squirrel cage slot; 6. Shaft hole; 7. Mounting section; 8. Reluctance section. DETAILED DESCRIPTION

[0049] See also Figures 1 to 4 As shown, according to an embodiment of the present application, the rotor assembly includes a rotor core 1. In a cross section perpendicular to the central axis of the rotor core 1, the rotor core 1 is provided with an axial hole 6, a slit slot 2, a q-axis squirrel cage slot 3 and a permanent magnet 4. The q-axis squirrel cage slot 3 is arranged at both ends of the slit slot 2, and the permanent magnet 4 is installed at both ends of at least part of the slit slot 2. The two permanent magnets 4 located in the same slit slot 2 are arranged at intervals.

[0050] According to the related art, each pole of the rotor assembly of a self-starting permanent magnet synchronous reluctance motor has a permanent magnetic barrier layer formed by multiple layers of slit slots 2 and q-axis squirrel cage slots 3. When the permanent magnet 4 is placed in the middle of the permanent magnetic barrier layer, that is, on the d-axis, the center of the rotor magnetic pole, that is, the d-axis position, is affected by the shaft hole 6, resulting in insufficient rotor core space in the d-axis direction. If a large magnetic flux is to be maintained, the width of the permanent magnet 4 must be guaranteed. This will cause the magnetic channel between adjacent permanent magnetic barrier layers to become narrower, which in turn causes the magnetic channel to become oversaturated, reducing the motor efficiency. If the magnetic channel is to be prevented from becoming oversaturated, the width of the permanent magnet 4 will be limited, resulting in a decrease in the motor magnetic flux and motor efficiency. Therefore, when the permanent magnet 4 is placed on the d-axis, no matter how the permanent magnet 4 and the width of the magnetic channel are adjusted, the motor efficiency will be reduced to a certain extent due to the limitation of the radial thickness of the rotor core 1 on the d-axis, which will increase the motor iron loss.

[0051] To solve the above problems, the present invention arranges the permanent magnets 4 located in the slit slots 2 at both ends of the slit slots 2, so that the permanent magnets 4 originally located on the d-axis are now located at both ends of the slit slots 2, avoiding the oversaturation phenomenon caused by the concentration of magnetic flux at the d-axis position, while ensuring the magnetic flux of the entire motor. In addition, the permanent magnets 4 are arranged at both ends of the slit slots 2, avoiding the rotor core with a smaller thickness in the d-axis direction, which is most affected by the shaft hole 6. This allows the space of the rotor core at both ends of the slit slots 2 to be fully utilized. This ensures that the permanent magnets 4 at both ends of the slit slots 2 have sufficient thickness to provide more magnetic flux, and that the width of the magnetic conductive channel between adjacent slit slots 2 is sufficient to avoid oversaturation. Therefore, on the one hand, the rotor space can be reasonably utilized for the arrangement of the permanent magnets 4, while ensuring the motor's reluctance torque, increasing the motor's permanent magnet torque, improving the motor's output and efficiency, and improving the motor's power factor. On the other hand, the permanent magnets 4 placed at both ends can also reduce the motor's iron loss, further improving the motor's efficiency. In this embodiment, the rotor assembly has a two-pole structure.

[0052] In addition, arranging the permanent magnets 4 at both ends of the slit slot 2 can also prevent the magnetic field direction of the permanent magnets 4 from being directly opposite to the stator demagnetization magnetic field, thereby effectively improving the demagnetization resistance of the permanent magnets 4.

[0053] In one embodiment, the slit slot 2 is at least two layers, and the width of the slit slot 2 in the d-axis direction increases from the middle to the two ends, and the width of the magnetic channel between adjacent slit slots 2 in the d-axis direction increases from the middle to the two ends, so that the width of the permanent magnet 4 along the d-axis direction can be greater than the width of the slit slot 2 on the d-axis, and at the same time, the width of the magnetic channel at the position where the permanent magnet 4 is located can be greater than the width of the magnetic channel on the d-axis. On the basis of the increase in thickness of the permanent magnet 4 and the increase in magnetic flux, the width of the magnetic channel is also increased, so that the width of the magnetic channel can still meet the magnetic conductivity requirements of the permanent magnet 4 with increased thickness, thereby avoiding the oversaturation of the magnetic channel, improving the magnetic flux of the motor, and increasing the permanent magnet torque of the motor while ensuring the reluctance torque of the motor, thereby improving the motor output and efficiency, and improving the power factor of the motor.

[0054] In one embodiment, the rare earth permanent magnet is used. Since the rare earth permanent magnet has the advantages of high remanence and strong anti-demagnetization capability, the anti-demagnetization capability of the permanent magnet 4 can be improved.

[0055] In one embodiment, the permanent magnets 4 are arranged in at least two layers, with the lengths of the permanent magnets 4 along the q-axis increasing radially inward along the d-axis. For example, in a rotor assembly including four layers of permanent magnets 4, the widths of the permanent magnets 4 along the d-axis radially inward are L1, L2, L3, and L4, respectively, where L4>L3>L2>L1.

[0056] In one embodiment, the permanent magnets 4 are arranged in at least two layers, and the minimum spacing between the permanent magnets 4 and the d-axis decreases radially inward from the d-axis. For example, in a rotor assembly including four layers of permanent magnets 4, the minimum spacing between the permanent magnets 4 and the d-axis is L8, L7, L6, and L5, respectively, radially inward from the d-axis, where L8>L7>L6>L5.

[0057] The above structure can limit the structure and position of the permanent magnet 4 along the radially inward direction d, thereby reducing the leakage magnetic field caused by the self-short circuit of the permanent magnet 4 and improving the utilization rate of the permanent magnet.

[0058] The slit slots 2 and the permanent magnets 4 are both multi-layered, and the number of layers of the slit slots 2 is greater than or equal to the number of layers of the permanent magnets 4, so that the magnetic resistance torque of the motor can be better utilized to improve the motor output.

[0059] In one embodiment, when the number of layers of the slit slots 2 is greater than the number of layers of the permanent magnets 4, the width of the slit slots 2 in the d-axis direction without the permanent magnets 4 installed increases in the direction away from the d-axis, and the slit slots 2 in which the permanent magnets 4 are installed include arc segments and straight segments, the straight segments are located at both ends of the arc segments, and the permanent magnets 4 are installed in the straight segments.

[0060] The slit slot 2 includes a magnetic resistance section 8 and a mounting section 7. The mounting section 7 is located at both ends of the magnetic resistance section 8 and extends along the q-axis. The permanent magnet 4 is mounted in the mounting section 7. The magnetization direction of the permanent magnet 4 is parallel to the d-axis.

[0061] The permanent magnets 4 are arranged at both ends of the slit slot 2. On the one hand, the rotor space can be reasonably utilized for the arrangement of the permanent magnets 4. While ensuring the reluctance torque of the motor, the permanent magnet torque of the motor is increased, the motor output and efficiency are improved, and the motor power factor is improved. Figure 3 The figure shows the torque comparison between the motor of the present application and the motor of the related art. On the other hand, the permanent magnets placed at both ends can also reduce the iron loss of the motor and further improve the efficiency of the motor. Figure 4 The figure shows the iron loss comparison between the motor of the present application and the motor of the related art.

[0062] from Figure 3 It can be seen that the motor torque of the present application is increased by about 10% compared with the motor torque in the related art, and the iron loss is reduced by about 10%, so the motor performance and efficiency are greatly improved.

[0063] In one embodiment, the q-axis cage slot 3 extends along the q-axis direction and is parallel to the q-axis, so that the q-axis cage slot 3 can cooperate with the slit slot 2 to form a smooth rotor magnetic conductive channel.

[0064] In one embodiment, the width of the magnetic channel between two adjacent q-axis cage slots 3 is d1, and the width of the magnetic channel between the two slit slots 2 corresponding to the two q-axis cage slots 3 is d2, where d1 ≥ d2, thereby ensuring that there is sufficient width between the q-axis cage slots 3 to avoid magnetic field saturation and affect the magnetic flux flow in the magnetic channel between adjacent permanent magnet magnetic barrier layers.

[0065] In one embodiment, the slit groove 2 includes an arc segment and a straight segment. The straight segments are located at both ends of the arc segment. The width of the arc segment in the d-axis direction increases gradually along the direction away from the d-axis.

[0066] In one embodiment, the curvature of the arc segments of the slit slots 2 decreases radially outward along the d-axis, with the outer arc curvature of the slit slots 2 on the same layer being smaller than the inner arc curvature. The outer arc refers to the arc radially outward along the d-axis within the slit slots 2 on the same layer, while the inner arc refers to the arc radially outward along the d-axis within the slit slots 2 on the same layer. An axial hole 6 is provided in the center of the rotor core 1. This arrangement maximizes rotor space utilization and allows for the rational arrangement of the slit slots 2 to increase the rotor salient pole ratio and enhance the motor's reluctance torque. The ends of the slit slots 2 extend into straight segments parallel to the q-axis, serving as mounting sections 7 for the permanent magnets 4. With these limitations, the positioning of the permanent magnets 4 can be designed based on the larger space near the outer periphery of the rotor core 1, utilizing the unique shape of the slit slots 2. This ensures the motor's reluctance torque while increasing the permanent magnet torque, further enhancing the motor's output.

[0067] The rotor core 1 is further provided with a d-axis cage slot 5 , which is located on a side of the q-axis cage slot 3 close to the d-axis.

[0068] In one embodiment, the d-axis cage slots 5 extend along the circumferential direction of the rotor core 1 .

[0069] In one embodiment, there is one d-axis cage slot 5 under the same pole, and the d-axis cage slot 5 is arranged on the d-axis.

[0070] In one embodiment, there are at least two d-axis cage slots 5 under one pole, and the at least two d-axis cage slots 5 are arranged at intervals along the circumferential direction of the rotor core 1 .

[0071] At the same pole, along the d-axis direction, the radial width of the d-axis squirrel cage slot 5 is m1, the radial width of the slit slot 2 located on the d-axis is m2, and the radial width between the outer circle of the shaft hole 6 and the rotor outer circle of the rotor core 1 is m3, where (m1+∑m2) / m3=0.3~0.5. The purpose is to select a reasonable magnetic barrier ratio to ensure sufficient magnetic barrier width and reasonable magnetic flux channel, increase the motor salient pole ratio, and prevent magnetic circuit oversaturation. Figure 5The figure shows the relationship curve between the output torque of the motor of the present application and (m1+∑m2) / m3. When (m1+∑m2) / m3 is in the range of 0.3 to 0.5, the motor can ensure a larger output torque. When (m1+∑m2) / m3 is less than 0.3 or greater than 0.5, the motor torque drops faster.

[0072] The total area of ​​the q-axis cage slot 3 and the d-axis cage slot 5 is S1, and the total area of ​​the q-axis cage slot 3, the d-axis cage slot 5 and the slit slot 2 is S2, wherein S1 / S2 = 30% to 70%, preferably, S1 / S2 = 35% to 50%. By reasonably limiting the ratio between S1 and S2, a certain proportion of the cage slot area can be guaranteed, so that the motor has a certain load starting capability. Figure 6 The figure shows the relationship curve between the pull-in torque and S1 / S2 of the motor of the present application technology. The pull-in torque first increases and then decreases with the increase of S1 / S2. When S1 / S2 is greater than 70%, the pull-in torque begins to decrease. When S1 / S2 is in the range of 30% to 70%, the motor can ensure a large pull-in torque. When S1 / S2 is in the range of 35% to 50%, the pull-in torque increases faster as S1 / S2 increases. 35% to 50% is a more optimal ratio range.

[0073] On the cross section of the rotor core 1, the angle formed by the line connecting the circumferential ends of the d-axis cage slot 5 and the central axis of the rotor core 1 is α1, where 20°≤α1≤60°. The total area of ​​the d-axis cage slot 5 under each pole is S3, and the maximum area of ​​a single q-axis cage slot 3 is S4, where S3≥2S4. This arrangement enables the d-axis cage slot 5 to form an arc-shaped magnetic barrier layer and serve as a cage slot. It can be used as a magnetic barrier layer to increase the magnetic resistance torque of the motor, and can also be used as a starting cage to improve the starting performance of the motor. Figure 7 The figure shows the relationship between the motor pull-in torque and efficiency and α1 of the present invention. As can be seen from the figure, the motor efficiency increases first and then decreases with the increase of α1, and the pull-in torque increases with the increase of α1. Considering the motor efficiency and pull-in torque comprehensively, α1 should satisfy 20°≤α1≤60°. Figure 8 The figure shows the relationship between the speed and S3 during the starting process of the motor of the present application technology. When S3≥2S4, the motor can successfully start to the synchronous speed. When S3<2S4, the motor speed fluctuates below the synchronous speed and cannot be pulled into synchronization.

[0074] The q-axis cage slots 3 and d-axis cage slots 5 are filled with a conductive, non-magnetic material, preferably aluminum or an aluminum alloy. End rings are provided at both ends of the rotor core 1, short-circuiting the q-axis cage slots 3 and d-axis cage slots 5 together to form a cage structure. The end rings are made of the same material as the slot filling. This self-shorting cage structure provides asynchronous torque during the motor's startup phase, enabling self-starting. The rotor's multi-layered permanent magnet barrier structure, consisting of the slit slots 2, cage slots, and permanent magnets 4, provides both permanent magnet torque and reluctance torque, enabling synchronous operation.

[0075] In one embodiment, the width of the shaft hole 6 on the d-axis is smaller than the width on the q-axis, and a flat shaft hole structure can be formed, thereby increasing the width of the rotor core 1 on the d-axis, increasing the rotor space, facilitating the arrangement of the slit slots 2 and the magnetic channel, and obtaining better motor performance.

[0076] In one embodiment, the shaft hole 6 is, for example, circular or elliptical, or can be a quasi-circular shape formed by a combination of an arc and a straight line.

[0077] According to an embodiment of the present application, a self-starting permanent magnet synchronous reluctance motor includes a stator and a rotor assembly, and the rotor assembly is the above-mentioned rotor assembly.

[0078] When the slit slots 2 and the permanent magnets 4 are both multi-layered and the magnetization direction of the permanent magnets 4 is parallel to the d-axis, the minimum thickness of each layer of the permanent magnets 4 along the magnetization direction is h, where 4σ≤h≤8.5σ, where σ is the radial width of the air gap between the stator and rotor cores 1. More preferably, h should satisfy 5σ≤h≤7σ, and optimally, h should satisfy 5.2σ≤h≤5.4σ, thereby ensuring that the permanent magnets have a high anti-demagnetization ability and improving the motor performance. Figure 9 The figure shows the relationship curve between the average magnetic flux density and efficiency of the permanent magnet of the motor of the present application technology and h / σ. As h / σ increases, the average magnetic flux density of the permanent magnet increases and the increase gradually decreases. When h / σ>8.5, the average magnetic flux density of the permanent magnet tends to remain unchanged. As h / σ increases, the efficiency of the motor first increases and then decreases. Selecting the ratio of h / σ can ensure that the average magnetic flux density of the permanent magnet is larger and the efficiency is higher.

[0079] In one embodiment, the width of the magnetic channel between two q-axis squirrel cage slots 3 adjacent to the q-axis is d3, and the width of the stator teeth is t, where d3>t, to ensure that the main magnetic circuit channel will not be saturated, while allowing the magnetic flux to effectively enter the stator teeth to generate torque. Figure 10 The figure shows the relationship between the motor output torque and d3 in the present application technology. d3>t can increase the motor output torque.

[0080] The minimum spacing between the q-axis cage slot 3 and the slit slot 2 on the same layer is h1, where 0.8σ≤h1≤2σ, where σ is the radial width of the air gap between the stator and rotor cores 1. This setting is intended to, on the one hand, ensure the mechanical strength of the rotor structure and reduce magnetic flux leakage between the q-axis cage slot 3 and the slit slot 2; on the other hand, the smooth connection between the q-axis cage slot 3 and the slit slot 2 can make the magnetic circuit of the rotor smooth and reduce the magnetic resistance of the rotor magnetic circuit. Figure 11 The figure shows the relationship curve between the leakage flux coefficient of the magnetic circuit between the q-axis squirrel cage slot 3 and the slit slot 2 in the motor of the present application technology and h1 / σ. As h1 / σ increases, the leakage flux coefficient increases, the leakage flux increases, and the motor performance deteriorates; however, the increase in h1 / σ will improve the mechanical strength of the motor. Considering the leakage flux and mechanical strength of the motor comprehensively, the range of h1 / σ is selected to be 0.8 to 2.

[0081] The minimum spacing between the q-axis squirrel cage slot 3 and the rotor outer circle of the rotor core 1 is h2, where h2>σ, σ is the radial width of the air gap between the stator and the rotor core 1, which can reduce the motor leakage and improve the motor efficiency while ensuring the mechanical strength of the rotor.

[0082] When the rotor core 1 is provided with q-axis cage slots 3, slit slots 2, permanent magnets 4 and d-axis cage slots 5, the q-axis cage slots 3, slit slots 2 and permanent magnets 4 located in the same layer form a permanent magnetic barrier layer, and / or, the q-axis cage slots 3 and slit slots 2 located in the same layer form a permanent magnetic barrier layer, and / or, the d-axis cage slots 5 located in the same layer form a permanent magnetic barrier layer, the minimum distance between adjacent permanent magnetic barrier layers is h3, and the minimum width of the permanent magnetic barrier layer with a smaller width along the d-axis direction in the adjacent permanent magnetic barrier layers is h4 in the d-axis direction, wherein h3≥1.8h4. This arrangement can also reduce the difficulty of rotor processing and ensure the uniformity and unsaturation of the rotor magnetic density distribution. Figure 12 and Figure 13 The following are the relationships between the output torque and iron loss of the motor of the present application technology and h3, h3≥1.8h4 can ensure the width of the magnetic barrier layer, increase the output torque, reduce iron loss, and improve the motor efficiency.

[0083] In this embodiment, the rotor core 1 includes three types of permanent magnetic barrier layers. The first type of permanent magnetic barrier layer is a permanent magnetic barrier layer formed by a single d-axis squirrel cage slot 5. The second type of permanent magnetic barrier layer is a permanent magnetic barrier layer formed by q-axis squirrel cage slots 3 and slit slots 2 in the same layer. The third type of permanent magnetic barrier layer is a permanent magnetic barrier layer formed by q-axis squirrel cage slots 3, slit slots 2 and permanent magnets 4 in the same layer. The three are arranged in sequence from the outside to the inside along the d-axis radial direction.

[0084] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0085] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A rotor assembly, characterized in that: The invention comprises a rotor core (1), wherein, on a cross section perpendicular to the central axis of the rotor core (1), the rotor core (1) is provided with an axial hole (6), a slit slot (2), a q-axis cage slot (3) and a permanent magnet (4), wherein the q-axis cage slot (3) is provided at both ends of the slit slot (2), and the permanent magnet (4) is installed at both ends of at least part of the slit slot (2), and two permanent magnets (4) located in the same slit slot (2) are arranged at intervals; The width of the slit slot (2) in the d-axis direction increases gradually from the middle to both ends, the q-axis squirrel cage slot (3) extends along the q-axis direction and is parallel to the q-axis, and the q-axis squirrel cage slot (3), the slit slot (2) and the permanent magnet (4) form a permanent magnetic barrier layer.

2. The rotor assembly according to claim 1, wherein: The slit groove (2) comprises an arc segment and a straight segment, and the straight segments are located at both ends of the arc segment.

3. The rotor assembly according to claim 2, wherein: The width of the arc segment in the d-axis direction increases gradually along the direction away from the d-axis.

4. The rotor assembly according to claim 1, wherein: The slit slots (2) are at least two layers, and the width of the magnetic channels between adjacent slit slots (2) in the d-axis direction increases gradually from the middle to both ends.

5. The rotor assembly according to claim 1, wherein: The slit slot (2) comprises a magnetic resistance section (8) and a mounting section (7), wherein the mounting section (7) is located at both ends of the magnetic resistance section (8), the mounting section (7) extends along the q-axis direction, the permanent magnet (4) is mounted in the mounting section (7), and the magnetization direction of the permanent magnet (4) is parallel to the d-axis.

6. The rotor assembly according to claim 5, wherein: The permanent magnets (4) are arranged in at least two layers, and along the radially inward direction of the d-axis, the lengths of the permanent magnets (4) along the q-axis direction gradually increase.

7. The rotor assembly according to claim 5, wherein: The permanent magnets (4) are arranged in at least two layers, and along the radially inward direction of the d-axis, the minimum distance between the permanent magnets (4) and the d-axis decreases.

8. The rotor assembly according to claim 1, wherein: The width of the magnetic channel between two adjacent q-axis cage slots (3) is d1, and the width of the magnetic channel between two slit slots (2) corresponding to the two q-axis cage slots (3) is d2, wherein d1≥d2.

9. The rotor assembly according to claim 1, wherein: The slit slot (2) and the permanent magnet (4) are both multi-layered, and the number of layers of the slit slot (2) is greater than or equal to the number of layers of the permanent magnet (4).

10. The rotor assembly according to claim 9, wherein: When the number of layers of the slit slots (2) is greater than the number of layers of the permanent magnets (4), the width of the slit slots (2) in the d-axis direction without the permanent magnets (4) installed increases in a direction away from the d-axis, and the slit slots (2) in which the permanent magnets (4) are installed include arc segments and straight segments, the straight segments are located at both ends of the arc segments, and the permanent magnets (4) are installed in the straight segments.

11. The rotor assembly according to claim 10, wherein: Along the radially outward direction of the d-axis, the curvature of the arc segment of the slit groove (2) decreases, and the outer arc curvature of the slit groove (2) located in the same layer is smaller than the inner arc curvature.

12. The rotor assembly according to claim 9, wherein: A d-axis squirrel cage slot (5) is further provided on the rotor iron core (1), and the d-axis squirrel cage slot (5) is located on a side of the q-axis squirrel cage slot (3) close to the d-axis.

13. The rotor assembly according to claim 12, wherein: The d-axis squirrel cage slots (5) extend along the circumferential direction of the rotor core (1).

14. The rotor assembly according to claim 13, wherein: There is one d-axis cage slot (5) under the same pole, and the d-axis cage slot (5) is arranged on the d-axis; or there are at least two d-axis cage slots (5) under the same pole, and the at least two d-axis cage slots (5) are arranged at intervals along the circumference of the rotor core (1).

15. The rotor assembly according to claim 12, wherein: At the same pole, along the d-axis direction, the radial width of the d-axis squirrel cage slot (5) is m1, the radial width of the slit slot (2) located on the d-axis is m2, and the radial width between the outer circle of the shaft hole (6) and the rotor outer circle of the rotor core (1) is m3, wherein (m1+∑m2) / m3=0.3~0.

5.

16. The rotor assembly according to claim 12, wherein: The total area of ​​the q-axis cage groove (3) and the d-axis cage groove (5) is S1, and the total area of ​​the q-axis cage groove (3), the d-axis cage groove (5) and the slit groove (2) is S2, wherein S1 / S2=30% to 70%.

17. The rotor assembly according to claim 12, wherein: On a cross section of the rotor core (1), an angle formed by a line connecting two circumferential ends of the d-axis squirrel cage slot (5) and the central axis of the rotor core (1) is α1, wherein 20°≤α1≤60°.

18. The rotor assembly according to claim 12, wherein: The total area of ​​the d-axis squirrel cage slots (5) under each pole is S3, and the maximum area of ​​a single q-axis squirrel cage slot (3) is S4, wherein S3≥2S4.

19. The rotor assembly according to claim 12, wherein: The q-axis cage slot (3) and the d-axis cage slot (5) are filled with conductive but non-magnetic material, and end rings are provided at both ends of the rotor core (1). The q-axis cage slot (3) and the d-axis cage slot (5) are short-circuited and connected via the end rings to form a cage structure.

20. The rotor assembly according to any one of claims 1 to 19, characterized in that The width of the shaft hole (6) on the d-axis is less than or equal to the width on the q-axis; and / or the rotor assembly is a two-pole structure.

21. A self-starting permanent magnet synchronous reluctance motor comprising a stator and a rotor assembly, characterized in that: The rotor assembly is the rotor assembly according to any one of claims 1 to 20.

22. The self-starting permanent magnet synchronous reluctance motor according to claim 21, characterized in that: When the slit slots (2) and the permanent magnets (4) are both multi-layered and the magnetization direction of the permanent magnets (4) is parallel to the d-axis, the minimum thickness of each layer of the permanent magnets (4) along the magnetization direction is h, where 4σ≤h≤8.5σ, and σ is the radial width of the air gap between the stator and the rotor core (1).

23. The self-starting permanent magnet synchronous reluctance motor according to claim 21, characterized in that: The width of the magnetic channel between two q-axis squirrel cage slots (3) adjacent to the q-axis is d3, and the width of the stator teeth is t, wherein d3>t.

24. The self-starting permanent magnet synchronous reluctance motor according to claim 21, characterized in that: The minimum spacing between the q-axis squirrel cage slot (3) and the slit slot (2) on the same layer is h1, where 0.8σ≤h1≤2σ, and σ is the radial width of the air gap between the stator and the rotor core (1).

25. The self-starting permanent magnet synchronous reluctance motor according to claim 21, characterized in that: The minimum spacing between the q-axis squirrel cage slot (3) and the rotor outer circle of the rotor core (1) is h2, wherein h2>σ, σ is the radial width of the air gap between the stator and the rotor core (1).

26. The self-starting permanent magnet synchronous reluctance motor according to claim 21, characterized in that: When the rotor core (1) is provided with q-axis cage slots (3), slit slots (2), permanent magnets (4) and d-axis cage slots (5), the q-axis cage slots (3), slit slots (2) and permanent magnets (4) located in the same layer form a permanent magnetic barrier layer, and / or the q-axis cage slots (3) and slit slots (2) located in the same layer form a permanent magnetic barrier layer, and / or the d-axis cage slots (5) located in the same layer form a permanent magnetic barrier layer, the minimum distance between adjacent permanent magnetic barrier layers is h3, and the minimum width of the permanent magnetic barrier layer with a smaller width along the d-axis direction in the adjacent permanent magnetic barrier layers in the d-axis direction is h4, wherein h3≥1.8h4.

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