Rare-earth-free permanent magnet wind driven generator rotor and generator with same

Abstract

The invention discloses a rare-earth-free permanent magnet wind driven generator rotor and a generator with the same. The rare-earth-free permanent magnet wind driven generator rotor comprises a rotor iron core and a plurality of magnetic barrier assemblies embedded in the circumferential direction of the rotor iron core. The magnetic barrier assembly comprises a plurality of magnetic barrier units which are distributed at intervals in the radial direction of the rotor core, each magnetic barrier unit comprises two permanent magnet cavities which are symmetrically arranged about the radial center line of the rotor core, and the two permanent magnet cavities incline outwards in the direction away from the radial center line of the rotor core; and a rare-earth-free permanent magnet is arranged in each permanent magnet cavity. According to the invention, the inclined permanent magnet cavity enables the direct-axis magnetic circuit to form high magnetic resistance and the quadrature-axis magnetic circuit to form low magnetic resistance, and the salient pole rate and the reluctance torque ratio can be improved by cooperating with the radially spaced magnetic barrier units; meanwhile, the rotor yoke part with slightly low magnetic conductivity is adopted, so that a magnetic field can be prevented from leaking towards the rotating shaft, the magnetic field is forced to be transmitted towards an outer air gap direction, and magnetic leakage of the yoke part is reduced.

Description

Technical Field

[0001] This invention relates to the field of generators, and particularly to a rare-earth-free permanent magnet wind turbine rotor and a generator having the same rotor. Background Technology

[0002] As a core component of wind power systems, the cost control of wind turbines directly determines the economic viability of wind power projects. Permanent magnet materials account for 40%-60% of the total cost of wind turbines, making them a key factor in cost structure. Traditional permanent magnet wind turbines generally rely on rare earth permanent magnet materials. These materials are not only expensive in the market, but their prices also fluctuate significantly due to factors such as resource reserves, severely restricting the cost stability of wind turbines.

[0003] Most existing semi-direct drive permanent magnet generators use a linear pole design, where magnets are arranged in a straight line and embedded into the core of the pole box, with the magnets bonded to the core. This structure has a relatively simple magnetic circuit design, which, while ensuring basic operational stability, results in essentially identical inductances along the quadrature and direct axes (dq axes). During operation, the motor relies solely on permanent magnet torque for electromagnetic torque, leading to extremely low reluctance torque utilization and no magnetizing effect. Excessive magnetic circuit symmetry results in insufficient difference in inductance between the quadrature and direct axes, with a saliency ratio (Lq / Ld) generally below 1.5, directly causing a decrease in motor power density of approximately 15-20%.

[0004] Against this backdrop, developing wind turbines based on rare-earth-free permanent magnet materials can solve the problems of high cost and unstable supply of traditional rare-earth permanent magnet materials, and reduce dependence on rare-earth resources. This has become an important technological direction for addressing the current cost dilemma of wind turbines and promoting the sustainable development of the wind power industry. Summary of the Invention

[0005] To address the problems of high cost and unstable supply caused by the reliance on rare-earth permanent magnet materials in traditional wind turbines, as well as the low saliency, poor reluctance torque utilization, and insufficient power density of existing linear magnetic pole structures, this invention provides a rare-earth-free permanent magnet wind turbine rotor and a generator incorporating it. The rotor includes a rotor core and several magnetic barrier components embedded circumferentially therein. Each magnetic barrier component contains radially spaced magnetic barrier units, and each unit has a permanent magnet cavity symmetrically inclined about the radial centerline. Rare-earth-free permanent magnets are installed within the cavities. Combined with a rotor yoke of specific permeability and a magnetic isolation structure, this invention achieves independence from rare-earth materials, reduces costs, and simultaneously improves saliency and reluctance torque utilization.

[0006] In a first aspect of the invention, a rare-earth-free permanent magnet wind turbine rotor is provided, which includes a rotor core and a plurality of magnetic barrier components embedded in the circumference of the rotor core.

[0007] The magnetic barrier assembly includes a plurality of magnetic barrier units distributed radially at intervals along the rotor core. Each magnetic barrier unit contains two permanent magnet cavities symmetrically arranged about the radial centerline of the rotor core. Both permanent magnet cavities are inclined outward in a direction away from the radial centerline of the rotor core, and the inclination angles of the two permanent magnet cavities are the same.

[0008] Each of the permanent magnet cavities is provided with a rare-earth-free permanent magnet. The polarity of the rare-earth-free permanent magnets in the two permanent magnet cavities in the same magnetic barrier unit is the same, and the polarity of the rare-earth-free permanent magnets in the magnetic barrier units corresponding to adjacent magnetic poles is opposite.

[0009] With the above technical solution, firstly, the present invention can eliminate the dependence on rare earth elements and significantly reduce the cost of permanent magnet materials; secondly, the tilted permanent magnet cavity in the present invention enables the direct-axis magnetic circuit to form high magnetic reluctance and the quadrature-axis magnetic circuit to form low magnetic reluctance. Combined with the radially spaced magnetic barrier units, it can improve the saliency ratio and increase the proportion of magnetic reluctance torque to compensate for the insufficient magnetic energy product of rare earth-free permanent magnets; at the same time, the two permanent magnet cavities in the present invention are symmetrical about the radial centerline and at the same angle. The magnetic fields generated are symmetrically superimposed at the air gap, which cancels the magnetic field offset caused by unilateral tilting, avoids local magnetic field concentration, reduces torque pulsation, reduces motor vibration and noise, and improves operational stability.

[0010] Preferably, along the radial direction of the rotor core, the included angle between the two permanent magnet cavities in each magnetic barrier unit gradually increases from the inside to the outside.

[0011] With the above technical solution, firstly, the small included angle of the inner magnetic barrier unit in this invention can concentrate the magnetic field towards the rotor yoke, reducing magnetic leakage in the direction of the rotating shaft, while the large included angle of the outer magnetic barrier unit can diffuse the magnetic field towards the air gap, enhancing the air gap magnetic flux density and further reducing radial magnetic leakage; secondly, the included angle gradient of different radial directions in this invention can match the magnetic reluctance requirements of different radial directions, making the magnetic reluctance difference between the direct axis and the quadrature axis more significant, which can further improve the saliency ratio.

[0012] Preferably, the rotor core includes a core body and a rotor yoke, wherein the rotor yoke is coaxially disposed on the inner side of the core body;

[0013] The permeability of the rotor yoke is 80%-90% of the permeability of the core body.

[0014] When the above technical solution is adopted, firstly, in this invention, the rotor yoke is located on the inner side and its permeability is slightly lower than that of the iron core body, which can prevent the magnetic field from leaking to the shaft and force the magnetic field to be transmitted to the outer air gap direction, thereby reducing magnetic leakage of the yoke; secondly, the slightly lower permeability of the yoke in this invention can absorb the local peak value of the radial magnetic field, further reducing the local saturation of the rotor and reducing torque pulsation.

[0015] Optionally, the rotor yoke can be made of low-grade silicon steel sheets, which can reduce the material cost of the rotor core without affecting the magnetic circuit performance. In addition, low-grade silicon steel sheets have better punching and processing properties, which can improve production efficiency.

[0016] Preferably, each of the permanent magnet cavities is provided with a first magnet hole and a second magnet hole at both ends;

[0017] The first magnet hole is located at one end of the permanent magnet cavity near the rotor yoke, and the second magnet hole is located at one end of the permanent magnet cavity away from the rotor yoke;

[0018] A first partition is provided between the permanent magnet cavity and the first magnet hole;

[0019] A second partition is provided between the permanent magnet cavity and the second magnet hole.

[0020] With the above technical solution, firstly, the first and second partitions in this invention are solid structures, respectively abutting against the two ends of the rare-earth-free permanent magnet, which can prevent the permanent magnet from moving axially along the cavity when the motor starts, stops, or changes speed, solving the problem of easy detachment of traditional adhesive fixing and improving the assembly stability of the permanent magnet; secondly, the first and second magnet holes in this invention are through holes, which, together with the solid magnetic circuit guidance of the partitions, can block the leakage of magnetic flux from both ends of the permanent magnet to the yoke and the rotor edge; at the same time, the first and second magnet holes in this invention can reduce the amount of material used in the rotor core, reduce the rotor weight, and the hole structure penetrates the rotor thickness direction to form an axial ventilation channel, which can help remove the heat generated by the permanent magnet during operation, reduce the working temperature of the permanent magnet, and avoid magnetic performance decay caused by high temperature.

[0021] Preferably, the magnetic barrier unit has a plurality of magnetic isolation holes in the middle, the plurality of magnetic isolation holes are arranged sequentially along the radial direction of the rotor core, and the center line connecting the plurality of magnetic isolation holes is collinear with the radial centerline of the rotor core;

[0022] The magnetic isolation hole is a hole structure that runs through the thickness direction of the rotor core, and the hole wall is provided with an insulating coating.

[0023] With the above technical solution, firstly, the magnetic isolation holes in this invention are located in the middle of the magnetic barrier unit and arranged radially in sequence, which can specifically block the transverse magnetic field leakage between the two permanent magnet cavities in the same magnetic barrier unit. Combined with the insulating coating on the hole wall, the magnetic isolation effect can be further improved. At the same time, the radially arranged hole structure can adapt to different radial magnetic field strengths by changing its size, thereby achieving gradient magnetic isolation and improving the accuracy of the magnetic circuit. In addition, the through structure of the magnetic isolation holes in this invention can further reduce the rotor weight, and the symmetrical arrangement of the holes can balance the mass distribution of the rotor.

[0024] Preferably, it further includes multiple first magnetic isolation bridges and multiple second magnetic isolation bridges, wherein:

[0025] Multiple first magnetic isolation bridges are respectively disposed between multiple first magnet holes and the magnetic isolation holes;

[0026] Multiple second magnetic isolation bridges are correspondingly disposed between multiple second magnet holes and the peripheral edge of the rotor core.

[0027] With the above technical solution, the first and second magnetic isolation bridges in this invention can reduce magnetic coupling, reduce magnetic leakage, and improve the independence of the magnetic circuit.

[0028] Preferably, the rotor core is further provided with auxiliary holes, which are located near the peripheral edge of the rotor core, and at least one auxiliary hole is provided on each magnetic pole.

[0029] With the above technical solution, firstly, the auxiliary holes in this invention are located at the periphery of the rotor, which can directly reduce the amount of material used in the rotor core, achieve a lightweight rotor design, and reduce the rotor's moment of inertia; secondly, the hole structure of the auxiliary holes in this invention forms an air reluctance region, which can specifically adjust the reluctance distribution of the local magnetic circuit of the rotor, further amplify the difference in reluctance between the quadrature and direct axes, improve the saliency ratio, and further compensate for the deficiency of insufficient magnetic energy product of rare-earth permanent magnets; at the same time, the auxiliary holes in this invention are close to the air gap and penetrate the thickness direction of the rotor, which can form a ventilation channel and form convection with the air gap airflow, quickly removing the heat from the rotor surface. In conjunction with the first magnet hole and the second magnet hole, the overall heat dissipation efficiency of the rotor can be significantly improved, ensuring that the permanent magnet and the core work at a suitable temperature and avoiding magnetic performance decay caused by high temperature.

[0030] Preferably, the auxiliary hole has a triangular cross-section, and the hole wall of the auxiliary hole is provided with an insulating coating of 0.5-1mm thickness;

[0031] The auxiliary hole, the magnetic shielding hole, the first magnet hole, and the second magnet hole are provided with rounded corner structures.

[0032] When the above technical solution is adopted, firstly, the insulating coating at this location in the present invention can fill the minor defects in the wall of the auxiliary hole, and prevent the hole wall from cracking due to stress concentration during high-speed rotation; secondly, it can further block magnetic leakage in the auxiliary hole area and improve the integrity of the magnetic circuit; at the same time, the rounded corner structure in the magnetic isolation hole, the first magnet hole and the second magnet hole in the present invention can disperse the stress around the hole, avoid core fatigue damage caused by stress concentration, and extend the service life of the rotor.

[0033] Preferably, each magnetic pole is provided with a pair of square holes below the magnetic barrier assembly, and the two square holes are symmetrically arranged based on the centerline of the rotor core.

[0034] Each of the square holes is provided with a screw to tighten and fix the rotor core.

[0035] With the above technical solution, firstly, the screw passing through the square hole in this invention tightens and fixes the rotor core, which can form a tight bond to the magnetic pole area, preventing the overall displacement of the magnetic poles when the motor rotates at high speed or vibrates, and solving the problem of insufficient reliability of bonding or pressure strip fixing; secondly, in this invention, one pair of square holes is symmetrically arranged based on the centerline of the rotor core, so that the tension of the screw is evenly distributed on both sides of the magnetic pole, which can avoid magnetic pole deformation caused by unilateral force and ensure the integrity of the magnetic circuit structure; in addition, the rigid fastening of the screw in this invention can improve the connection strength between the magnetic pole and the rotor core, which can resist the severe vibration and impact in the wind power scenario and ensure the long-term stable operation of the rotor.

[0036] In a second aspect of the invention, a generator is also provided, comprising a stator, a shaft, and the aforementioned rare-earth-free permanent magnet wind turbine rotor. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the rotor structure provided in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram comparing the saliency of the present invention with that of the prior art.

[0040] Figure Labels

[0041] 11. Iron core body; 12. Rotor yoke; 2. Rare earth-free permanent magnet; 31. First magnet hole; 32. Second magnet hole; 4. Magnetic isolation hole; 5. Auxiliary hole; 6. Square hole. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] As described in the background section, existing semi-direct drive permanent magnet generators mostly employ a linear pole design, where magnets are arranged in a straight line and embedded into the core of the pole box, with the magnets bonded and fixed to the core. This structure has a relatively simple magnetic circuit design, which, while ensuring basic operational stability, results in essentially identical inductances along the quadrature and direct axes (dq axes). During operation, the motor relies solely on permanent magnet torque for electromagnetic torque, leading to extremely low reluctance torque utilization and no magnetizing effect. Excessive magnetic circuit symmetry results in insufficient difference in inductance between the quadrature and direct axes, with a saliency ratio (Lq / Ld) generally below 1.5, directly causing a 15-20% decrease in motor power density. Against this backdrop, developing wind turbines based on rare-earth-free permanent magnet materials can solve the problems of high cost and unstable supply of traditional rare-earth permanent magnet materials, while reducing dependence on rare-earth resources. This has become an important technological direction for addressing the current cost dilemma of wind turbines and promoting the sustainable development of the wind power industry.

[0045] In a first aspect of the invention, a rare-earth-free permanent magnet wind turbine rotor is proposed, which aims to solve the technical problems of high cost and unstable supply caused by the reliance on rare-earth permanent magnet materials in traditional wind turbines, as well as the low saliency of existing linear magnetic pole structures, poor magnetic reluctance torque utilization, and insufficient power density. The invention eliminates the reliance on rare earth materials and improves the performance of the generator by setting up multi-layer magnetic barrier components, gradient magnetic circuits, and magnetic isolation structures.

[0046] Specifically, in the exemplary embodiment, reference is made to Figure 1 The rare-earth-free permanent magnet wind turbine rotor of this embodiment includes a rotor core and a number of magnetic barrier components embedded in the circumference of the rotor core. The number of magnetic barrier components is the same as the number of generator magnetic poles. In this embodiment, it is preferred to have 24 magnetic poles, that is, 24 magnetic barrier components are evenly distributed along the circumference of the rotor core, and the central angle between two adjacent magnetic barrier components is 15° to ensure the uniformity of the air gap magnetic field.

[0047] Specifically, in the exemplary embodiment, the rotor core includes a core body 11 and a rotor yoke 12. The rotor yoke 12 is coaxially disposed inside the core body 11 (close to the shaft to be assembled later). Both are made of silicon steel sheets stacked together, with a stacking factor of not less than 0.95, to ensure good magnetic permeability and structural strength. The core body 11 uses 35W300 grade silicon steel sheets, while the rotor yoke 12 uses structural steel with a lower permeability than the core body 11. The permeability of the rotor yoke 12 is 85% of that of the core body 11, which can prevent magnetic field leakage to the shaft and force the magnetic field to be transmitted to the outer air gap direction, reducing magnetic leakage in the yoke. In addition, the slightly lower permeability of the rotor yoke 12 can absorb local peaks in the radial magnetic field, reduce local oversaturation of the rotor, and reduce torque pulsation.

[0048] Furthermore, in the exemplary embodiment, each magnetic barrier assembly includes three magnetic barrier units (i.e., inner layer, middle layer, and outer layer) distributed radially at intervals along the rotor core, with a predetermined gap reserved between adjacent magnetic barrier units. Each magnetic barrier unit contains two permanent magnet cavities symmetrically arranged about the radial centerline of the rotor core. Both permanent magnet cavities are inclined outward in a direction away from the radial centerline of the rotor core, and the inclination angles of the two permanent magnet cavities are the same.

[0049] Furthermore, in the exemplary embodiment, along the radial direction of the rotor core, the included angle between the two permanent magnet cavities in each magnetic barrier unit gradually increases from the inside to the outside. Specifically, the included angle between the two permanent magnet cavities in the inner magnetic barrier unit is 60°, in the middle layer it is 110°, and in the outer layer it is 150°. This gradient angle can concentrate the inner magnetic field towards the rotor yoke 12, reducing leakage magnetic flux in the direction of the rotating shaft, and diffuse the outer magnetic field towards the air gap, enhancing the air gap magnetic flux density.

[0050] Furthermore, the inner magnetic barrier unit has the longest permanent magnet cavity, while the lengths of the permanent magnet cavities in the middle and outer magnetic barrier units decrease sequentially. The length of the subsequently assembled rare-earth-free permanent magnet 2 also decreases accordingly with the length of its corresponding permanent magnet cavity. Combined with the aforementioned design where the angle between the two permanent magnet cavities of the magnetic barrier unit increases from the inside out, the length gradient and the angle gradient work together to form a more precise radial reluctance gradient. That is, the long inner permanent magnet cavity extends the direct-axis high reluctance path, while the shortened middle and outer layers reduce the obstruction of the quadrature-axis magnetic circuit, further amplifying the difference in reluctance between the quadrature and direct axes, further improving the saliency ratio, and compensating for the insufficient magnetic energy product of the rare-earth-free permanent magnet 2. In addition, the shortened middle and outer permanent magnet cavities and permanent magnets reduce the weight of the rotor's outer periphery, reducing centrifugal force during high-speed rotation and ensuring a uniform radial weight distribution of the rotor.

[0051] Furthermore, in the exemplary embodiment, the cross-section of the permanent magnet cavity is rectangular, and the cavity wall is polished to ensure a good fit with the rare-earth-free permanent magnet 2. Each permanent magnet cavity contains a tightly fitted rare-earth-free permanent magnet 2. In this embodiment, the rare-earth-free permanent magnet 2 is made of ferrite permanent magnet material, and its shape is adapted to the inner shape of the permanent magnet cavity, forming a cuboid structure. The rare-earth-free permanent magnets 2 in the two permanent magnet cavities within the same magnetic barrier unit have the same polarity, and the rare-earth-free permanent magnets 2 in adjacent magnetic barrier components have opposite polarities (i.e., N pole → S pole → N pole… alternating arrangement) to form a continuous rotating magnetic field in the air gap. During the assembly of the rare-earth-free permanent magnet 2, an epoxy resin adhesive is first coated on the inner wall of the permanent magnet cavity, and then the rare-earth-free permanent magnet 2 is embedded into the cavity and left to cure for 24 hours to ensure a firm connection.

[0052] Specifically, in the exemplary embodiment, each permanent magnet cavity has a first magnet hole 31 and a second magnet hole 32 at both ends. The first magnet hole 31 is located at the end of the permanent magnet cavity near the rotor yoke 12, and the second magnet hole 32 is located at the end of the permanent magnet cavity away from the rotor yoke 12. A first partition is provided between the permanent magnet cavity and the first magnet hole 31, and a second partition is provided between the permanent magnet cavity and the second magnet hole 32. Both the first and second partitions are solid structures integrally stamped from the rotor core, with a thickness of 1-2 mm, to abut against the two ends of the rare-earth-free permanent magnet 2, thereby preventing the permanent magnet from moving axially along the cavity when the generator starts, stops, or changes speed.

[0053] Furthermore, in the exemplary embodiment, two magnetic isolation holes 4 are provided in the middle of the magnetic barrier unit. The two magnetic isolation holes 4 are arranged sequentially along the radial direction of the rotor core and are located between the inner magnetic barrier unit and the middle magnetic barrier unit, respectively. The center line connecting the two magnetic isolation holes 4 is collinear with the radial centerline of the rotor core. The magnetic isolation holes 4 are oblong holes that penetrate the thickness direction of the rotor core. The hole walls are coated with a 0.8mm thick epoxy resin insulating coating, which can specifically block the transverse magnetic field leakage between the two permanent magnet cavities within the same magnetic barrier unit. In this embodiment, the diameter of the two magnetic isolation holes 4 gradually decreases from the inside to the outside to adapt to different radial magnetic field strengths and achieve gradient magnetic isolation.

[0054] Furthermore, the rotor in this embodiment also includes multiple first magnetic isolation bridges and multiple second magnetic isolation bridges. The multiple first magnetic isolation bridges are respectively disposed between multiple first magnet holes 31 and magnetic isolation holes 4, and the multiple second magnetic isolation bridges are respectively disposed between multiple second magnet holes 32 and the peripheral edge of the rotor core. The first and second magnetic isolation bridges can prevent the magnetic field from leaking to the yoke or the rotor edge, and at the same time fill the gaps between the hole structures, thereby improving the overall rigidity of the rotor.

[0055] Furthermore, corresponding to the inner, middle, and outer magnetic barrier units, the size of the second magnetic isolation bridge gradually decreases to adapt to the radial magnetic field strength gradient and control magnetic leakage. Along the radial direction of the rotor core, the magnetic field strength decreases from the inside to the outside. The inner magnetic barrier unit corresponds to a higher magnetic field strength, and a larger second magnetic isolation bridge can minimize magnetic leakage. Conversely, the outer magnetic barrier unit corresponds to a lower magnetic field strength, and reducing the size of the second magnetic isolation bridge can reduce the redundancy of the magnetic conductive material. This avoids magnetic circuit interference caused by an excessively large magnetic isolation bridge and further amplifies the difference in reluctance between the quadrature and direct axes by moderately increasing the outer magnetic reluctance. Combined with the included angle gradient and length gradient of the magnetic barrier unit, this synergistically increases the saliency ratio and further compensates for the insufficient magnetic energy product of the rare-earth-free permanent magnet 2.

[0056] Furthermore, in the exemplary embodiment, auxiliary holes 5 are also provided on the rotor core. These auxiliary holes 5 are located near the peripheral edge of the rotor core, and one auxiliary hole 5 is provided on each magnetic pole. The cross-section of the auxiliary hole 5 is triangular, and its wall is provided with a 0.5-1mm thick insulating coating, which can further block magnetic leakage in this area. In addition, the auxiliary holes 5, the magnetic isolation holes 4, the first magnet hole 31, and the second magnet hole 32 all have rounded corner structures, which can disperse the stress around the holes and avoid fatigue damage to the core caused by stress concentration.

[0057] Furthermore, in the exemplary embodiment, each magnetic pole is provided with a pair of square holes 6 below the magnetic barrier assembly. The two square holes 6 are symmetrically arranged based on the centerline of the rotor core. The cross-section of the square holes 6 is rectangular. A screw is inserted into each square hole 6. After the two ends of the screw extend out of the square hole 6, spring washers and nuts are respectively fitted. The rotor core is tightened and fixed by tightening the nuts, ensuring the structural stability of the magnetic pole area and avoiding the overall displacement of the magnetic pole when the generator rotates or vibrates at high speed.

[0058] In a second aspect of the invention, a rare-earth-free permanent magnet wind turbine is also provided, comprising a stator, a shaft, and the aforementioned rare-earth-free permanent magnet wind turbine rotor.

[0059] When the rare-earth-free permanent magnet wind turbine is working, the wind power drives the shaft to rotate, which in turn drives the rotor to rotate synchronously. The rare-earth-free permanent magnets 2 on the rotor form a continuous and uniform rotating magnetic field in the air gap through a multi-layer magnetic barrier assembly; the stator windings cut the magnetic field lines to generate an induced electromotive force, realizing the conversion of mechanical energy into electrical energy.

[0060] During this process, the inclined permanent magnet cavity allows the d-axis magnetic circuit to pass through the gap between the multi-layer rare-earth-free permanent magnet 2 and the magnetic barrier unit to form high magnetic reluctance, while the q-axis magnetic circuit is transmitted along the high permeability rotor core to form low magnetic reluctance. Combined with the radially spaced magnetic barrier units and the magnetic isolation structure, the saliency ratio is significantly improved, the proportion of magnetic reluctance torque is increased, and the defect of insufficient magnetic energy product of rare-earth-free permanent magnet 2 is compensated. The rotor yoke 12 with lower permeability reduces yoke leakage magnetic field, improves the air gap magnetic field distribution, and reduces the torque pulsation of the motor. The auxiliary hole 5, the first magnet hole 31, and the second magnet hole 32 form a ventilation channel to quickly remove the heat generated during rotor operation and ensure stable operation of the generator.

[0061] Specifically, performance tests were conducted on the rare-earth-free permanent magnet wind turbine of this embodiment, referring to... Figure 2 The results showed that the generator's saliency ratio (Lq / Ld) reached 3.29, which compensated for the deficiency of insufficient magnetic energy product in the absence of rare earth permanent magnets; torque ripple was controlled within 1.5%, and operating vibration and noise were significantly reduced.

[0062] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0063] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A rare-earth-free permanent magnet wind turbine rotor, characterized in that, It includes a rotor core and a plurality of magnetic barrier components embedded in the circumference of the rotor core; The magnetic barrier assembly includes a plurality of magnetic barrier units distributed radially at intervals along the rotor core. Each magnetic barrier unit contains two permanent magnet cavities symmetrically arranged about the radial centerline of the rotor core. Both permanent magnet cavities are inclined outward in a direction away from the radial centerline of the rotor core, and the inclination angles of the two permanent magnet cavities are the same. Each of the permanent magnet cavities is provided with a rare-earth-free permanent magnet. The polarity of the rare-earth-free permanent magnets in the two permanent magnet cavities in the same magnetic barrier unit is the same, and the polarity of the rare-earth-free permanent magnets in the magnetic barrier units corresponding to adjacent magnetic poles is opposite.

2. The rare-earth-free permanent magnet wind turbine rotor according to claim 1, characterized in that, Along the radial direction of the rotor core, the included angle between the two permanent magnet cavities in each magnetic barrier unit gradually increases from the inside to the outside.

3. The rare-earth-free permanent magnet wind turbine rotor according to claim 1, characterized in that, The rotor core includes a core body and a rotor yoke, with the rotor yoke coaxially disposed on the inner side of the core body. The permeability of the rotor yoke is 80%-90% of the permeability of the core body.

4. The rare-earth-free permanent magnet wind turbine rotor according to claim 3, characterized in that, Each of the permanent magnet cavities is provided with a first magnet hole and a second magnet hole at both ends; The first magnet hole is located at one end of the permanent magnet cavity near the rotor yoke, and the second magnet hole is located at one end of the permanent magnet cavity away from the rotor yoke; A first partition is provided between the permanent magnet cavity and the first magnet hole; A second partition is provided between the permanent magnet cavity and the second magnet hole.

5. The rare-earth-free permanent magnet wind turbine rotor according to claim 4, characterized in that, The magnetic barrier unit has multiple magnetic isolation holes in its middle part. The multiple magnetic isolation holes are arranged sequentially along the radial direction of the rotor core, and the center line connecting the multiple magnetic isolation holes is collinear with the radial centerline of the rotor core. The magnetic isolation hole is a hole structure that runs through the thickness direction of the rotor core, and the hole wall of the magnetic isolation hole is provided with an insulating coating of 0.5-1mm thickness.

6. The rare-earth-free permanent magnet wind turbine rotor according to claim 5, characterized in that, It also includes multiple first magnetic isolation bridges and multiple second magnetic isolation bridges, wherein: Multiple first magnetic isolation bridges are respectively disposed between multiple first magnet holes and the magnetic isolation holes; Multiple second magnetic isolation bridges are correspondingly disposed between multiple second magnet holes and the peripheral edge of the rotor core.

7. The rare-earth-free permanent magnet wind turbine rotor according to claim 5, characterized in that, The rotor core is also provided with auxiliary holes, which are located near the peripheral edge of the rotor core, and at least one auxiliary hole is provided on each magnetic pole.

8. The rare-earth-free permanent magnet wind turbine rotor according to claim 7, characterized in that, The auxiliary hole has a triangular cross-section, and the hole wall is provided with an insulating coating of 0.5-1mm thickness. The auxiliary hole, the magnetic shielding hole, the first magnet hole, and the second magnet hole are provided with rounded corner structures.

9. The rare-earth-free permanent magnet wind turbine rotor according to any one of claims 1-8, characterized in that, Each magnetic pole is provided with a pair of square holes below the magnetic barrier assembly, and the two square holes are symmetrically arranged based on the centerline of the rotor core. Each of the square holes is provided with a screw to tighten and fix the rotor core.

10. A generator, characterized in that, It includes a stator, a shaft, and a rare-earth-free permanent magnet wind turbine rotor as described in any one of claims 1-9.

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