WO2012012978A1

WO2012012978A1 - Magnetic steel for permanent-magnet direct-driven wind mill generator

Info

Publication number: WO2012012978A1
Application number: PCT/CN2010/078361
Authority: WO
Inventors: 武树森; 贾大江; 吕先明; 李勇
Original assignee: 上海万德风力发电股份有限公司
Priority date: 2010-07-26
Filing date: 2010-11-03
Publication date: 2012-02-02
Also published as: CN102340188A

Abstract

A magnetic steel for a permanent- magnet direct-driven wind mill generator is provided. The cross section of the magnetic steel is a rectangle in the center of which a through hole is provided. The upper surface (2) and the lower surface (7) of the magnetic steel are arches. The lateral surface of the magnetic steel includes an upper lateral surface (6), a middle lateral surface (4) and a lower lateral surface (3). The magnetic steel has the advantages of being fixed well and a low cost.

Description

Permanent magnet direct drive wind turbine magnet

[Technical Field] The present invention relates to a magnetic steel for a generator, and more particularly to a magnetic steel for a permanent magnet direct drive wind power generator.

[Background technique]

The permanent magnet synchronous generator can be divided into two types: outer rotor and inner rotor. We know the relationship between air gap, diameter and motor capacity. It is clear that the electrical performance of the same air gap and diameter of the motor, the outer rotor structure and the inner rotor structure is indistinguishable.

The magnet of the permanent magnet motor of the inner rotor type is fixed on the outer side or the outer surface of the rotor. If the permanent magnet of the permanent magnet motor of the inner rotor is fixed on the outer surface of the inner rotor, a pressure ring is generally added outside the permanent magnet. Used to protect the magnet. Another method is to fasten the magnet to the dovetail groove on the specially machined rotor and secure it with a wedge. But no matter how it is fixed, its processing requirements are very high and strict. This makes processing difficult and costly.

However, since the magnet of the permanent magnet motor of the inner rotor type is fixed to the outer side or the outer surface of the rotor, if the motor speed is high, the centrifugal force will be large (centrifugal force? = 1111, 0) 2, 10, which is a magnet for preventing permanent magnets. The first method is to use a pressure ring on the outer surface of the permanent magnet to protect the magnet if the permanent magnet of the permanent magnet motor of the inner rotor is fixed on the outer surface of the inner rotor. Another method is to fasten the magnet to the dovetail groove on the specially machined rotor and secure it with a wedge. However, regardless of the method used, the processing requirements are very high and strict. This makes processing difficult and costly.

There are four types of rotor magnetic circuits in the inner rotor permanent magnet synchronous generator, which are radial, tangential, axial and hybrid. In practical applications, the tangential structure and radial magnetization are often used. Most of the structure, because the radial magnetization structure has a small magnetic flux leakage coefficient because the magnetic pole directly faces the air gap, and its yoke is a whole piece of magnetizer, and avoids the problem of excessive axial size during axial excitation. , process realization capacity In the radial and magnetized structure, the magnetic induction of the air gap is close to the magnetic induction intensity of the working point of the permanent magnet. Although there is no air gap magnetic density as large as the tangential structure, it is not too low, so the radial structure has obvious superiority. Sex, it is also a rotor magnetic circuit structure that is widely used in the design of large-scale wind turbines.

In the tangential magnetization structure, the magnetization direction of the permanent magnet is nearly perpendicular to the air gap flux axis and far from the air gap, and the magnetic flux leakage is larger than the radial structure. In the tangential magnetization structure, the permanent magnets are in parallel state. The magnetic flux per pole of the generator is provided by two rare earth permanent magnets, which can improve the air gap magnetic density, especially in the case of a large number of poles.

The tangential rotor magnetic circuit structure can be divided into a tangential collar structure and a tangential groove wedge structure due to the different fixing methods of the permanent magnet and the pole piece. Permanent magnet materials, especially in rare earth cobalt permanent magnet materials, have low tensile strength. If there is no protective measure on the rotor, when the rotor diameter of the generator is large or high speed, the centrifugal force on the surface of the rotor will cause damage to the permanent magnet. Therefore, a ring is generally added to the outer surface of the synchronous generator rotor that is running at a high speed, and the permanent magnet and the soft iron pole piece are fixed in the corresponding positions by the collar.

The magnetic flux path of the tangential collar rotor magnetic circuit structure is: permanent magnet N pole one soft iron pole piece set of ring magnetic material section a soft iron pole piece a permanent magnet S pole. It can be seen from the magnetic flux path that a part of the collar is a component of the main magnetic circuit, and the magnetic permeability is required, and the other part of the collar is the interval between the two magnetic poles, and the magnetic separation is required. Therefore, the collar is composed of a high-precision, high-resistivity magnetic metal material and a non-magnetic material. The path between the permanent magnet and the soft iron pole shoe and the inner wall of the collar is the path of the main magnetic flux, and the parts must be processed with high precision.

In the tangential groove wedge structure, the permanent magnet is fixed by the slot wedge, and the process and structure are relatively simple. Some generators divide the rotor into several sections along the axial direction, and each section is a disk. When assembling, each disk is separately performed. Assemble, then put all the disks on the reels.

The magnetization direction of the permanent magnet in the radial rotor magnetic circuit structure is consistent with the air gap flux axis and close to the air gap, and the magnetic flux leakage coefficient is smaller than the tangential structure. The radial magnetization structure and the rare earth permanent magnet work in the roadblock state, only The area of a permanent magnet provides the flux flux at each pole of the generator. Therefore, the air gap magnetic density is relatively low. The shape of the permanent magnet in the radial rotor magnetic circuit structure mainly includes four types: a ring shape, a star shape, a tile type and a rectangle shape.

In order to reduce the diameter of the rotor as much as possible, and to improve the air gap magnetic density, and considering the high coercive force of the rare earth permanent magnet, the magnetization direction length of the permanent magnet can be small, and tile-shaped permanent magnets and rectangular permanent magnets are often used. Rectangular hydromagnets have low processing costs and magnetization, and the magnetic properties of the same are best. Tile-shaped ice magnets can also be composed of rectangular permanent magnet strips to reduce permanent magnet processing costs. Adjusting the width of the tile-shaped permanent magnet and the shape and width of the rectangular permanent magnet pole piece, that is, adjusting the pole piece coefficient, can improve the air gap magnetic field waveform.

The hybrid rotor magnetic circuit structure places permanent magnets in both radial and tangential directions, which can provide higher air gap magnetic density at a certain rotor diameter, or can reduce the rotor volume under the same air gap magnetic density. . In the case where the radial permanent magnets of the tangential permanent magnets have the same size, the amount of permanent magnets is reduced. The hybrid rotor has a complicated structure, requires high processing precision for the rotor groove type and the permanent magnet, and is time-consuming to manufacture.

The representative structure of the axial rotor is a claw pole rotor, which has the advantages of simple shape of the permanent magnet, good magnetic performance, uniform magnetization and high utilization rate. The disadvantage is that the claw pole structure is complicated, the manufacturing is difficult, the time-consuming, the large capacity unit, the claw Extremely subject to centrifugal force, special tightening measures are required. The ratio of the claw pole and the flange to the rotor volume is large, and the motor quality is increased. It is not suitable to be a power frequency generator. The pulsation loss in the claw pole is large and the efficiency is lowered.

[Summary of the Invention]

The object of the present invention is to provide a permanent magnet direct drive wind power generator magnetic steel with simple structure, good processability and low cost in order to overcome the defects of the prior art described above. The object of the present invention can be achieved by the following technical solutions: Designing a magnetic steel for a permanent magnet direct-drive wind power generator, characterized in that the magnetic steel has a rectangular cross section, a through hole in the center thereof, and an upper surface thereof Arched, the lower surface is arched, and the sides include the upper side, the middle side, and the lower side. The through hole includes an upper portion and a lower portion, wherein the upper portion is a rounded table body and the lower portion is a cylindrical body. The upper surface has the same diameter as the arcuate arc of the lower surface. 1 The upper side is rectangular. The middle side is arched. The lower side is rectangular. The surface of the magnetic steel is galvanized. The permanent magnet material type is sintered NdFeB 42SH; remanence (Br) 1.23~1.29 T _; maximum magnetic energy product (BH) max^36MGOe _; intrinsic coercivity (Hcj) ^ 19kOe; intrinsic coercivity ( Hcj) temperature coefficient > -0.55 % / ° ((201 ~ 150); bulk magnet bonding performance under room temperature conditions > 10 3, shear strength > 120 MPa at 120 ° C, bonding layer insulation > 500 Μ Ω.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural view of the present invention;

Figure 2 is a cross-sectional view taken along line B-B of Figure 1 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings and specific embodiments.

Example

As shown in FIG. 1 and FIG. 2, a magnetic steel for a permanent magnet direct-drive wind power generator, the magnetic steel has a rectangular cross section, a through hole is arranged in the center, and an upper surface 2 is arched, and the lower surface 7 is In the shape of an arch, the side surface includes an upper side 6, a middle side 4, and a lower side 3. The through hole includes an upper portion 1 and a lower portion 5, wherein the upper portion 1 is a rounded table body and the lower portion 5 is a cylindrical body. The upper surface 2 and the arcuate arc of the lower surface 7 have the same diameter. The upper side 6 is rectangular. The middle side 4 is arched. The lower side 3 is rectangular.

4

Correction page (Article 91) At the center of the magnetic steel, there is a through hole which can be fixed by a countersunk head screw, and the upper side and the lower side are regarded as a rectangular shape, and the bottom surface has a circular arc shape with the same radius as the outer circumference of the rotor, and the surface of the magnetic steel is galvanized.

The main technical parameters:

Permanent magnet material type: sintered NdFeB 42SH,

(1) Remanence (Br): 1.23~1.29 T;

(2) Maximum magnetic energy product (BH) max: ^36MGOe _;

(3) Intrinsic coercivity (Hcj): ^ 19kOe _;

(4) Temperature coefficient of intrinsic coercivity (Hcj): better than -0.55 % / ° C (20 ° C ~ 150 ° C);

(5) Bonding properties of bulk magnets are: room temperature, shear strength > 10MPa, 120 °C, shear strength >5^&. Bonding layer insulation >500Μ Ω. A new method of fixing the magnetic steel on the outer surface of the inner rotor of the present invention is to use a fixing screw, an anaerobic adhesive, an insulating sheet bead and a high-density glass fiber cloth and an epoxy resin to surround the composite fixing method of closing the outer surface of the entire rotor.

Since the magnet of the present invention is a permanent magnet direct drive generator specifically for wind power generation, it must be noted that it must be used for a direct drive type motor. Since the direct drive motor is a low speed motor, its maximum speed is not allowed to exceed 30 rpm.

The center of the magnetic steel has a through hole for wearing a fixing screw, and the surface is galvanized. When installing, first coat the surface of the rotor shell to which the magnetic steel is to be mounted with anaerobic adhesive, and then align the through hole of the magnetic steel with the mounting hole, and then press the center of each magnetic steel with the non-magnetic stainless steel countersunk head screw of lCrl8Ni9Ti. Positioning. The barrier between the magnets is an insulating plate.

After all the magnetic steels have been installed, the outer surface of the entire rotor is closed with a 0.1 mm thick high-density glass fiber cloth and epoxy resin.

This high-density glass ff cloth and epoxy resin have a strong mechanical strength around the sealing layer.

5

Correction page (Article 91) It can effectively prevent the NdFeB magnet from falling off and oxidizing. The invention has double layer fastening and good oxidation prevention of neodymium iron boron magnetic steel.

The innovation of the present invention is due to the use of the magnetic steel, and the magnetic steel that can be used in the permanent magnet wind power generator has a new hybrid fixing method. _

Because the permanent magnet motor's high quality permanent magnet material, such as NdFeB permanent magnet material, is a mixture of metallic iron, rare earth lanthanum and 'non-metallic boron. Among them, the production of magnetic steel is to first make various alloy thin plates, and then crush various materials and then make a mixture according to the design ratio, and then press it into the shape and size of the design to make 3⁄4. The permanent magnet used in the permanent magnet motor is subjected to high-temperature sintering and heat treatment after press molding, and finally subjected to surface treatment. Due to the permanent magnet preparation process, the tensile strength of the permanent magnet cannot be made very high.

However, since the magnet of the permanent magnet motor of the conventional inner rotor type is fixed on the outer side or the outer surface of the rotor, if the motor speed is high, the centrifugal force will be large (centrifugal force F = πι · ω2 · R), usually the generator magnet is avoided. The stress concentration does not cause the magnet to break under the centrifugal force, so holes are not allowed on the magnet.

Since the magnetic steel of the present invention is a permanent magnet direct-drive generator specifically for wind power generation, it must be noted that it must be used for a direct drive type motor. Since the direct drive motor is a low speed motor, its maximum speed is not allowed to exceed 30 rpm. After careful analysis, the centrifugal force of the magnet on the inner rotor of the permanent magnet direct-drive wind turbine is only a few thousandth of that of a conventional motor. '

For example, the rated speed of the 6-stage motor with the same diameter and the same magnetic steel is 1000 rpm, and the rated speed of our 1.5MW permanent magnet motor is only 20 rpm, so the rated speed of our 1.5MW permanent magnet motor is The centrifugal force is only 1/2500 of the centrifugal force of the 6-stage motor with the same mass and the same diameter. The 1.5MW motor magnet of our company is much less centrifugal force!

In this way, we can design an inner rotor manufacturing method different from conventional high speed motors. In the present invention, the magnetic steel has a rectangular shape and a through hole at the center for wearing a fixing screw. The magnetic shape is simple and easy to manufacture.

6

Correction page (Article 91) The 1.5MW permanent magnet direct-drive wind power generator of the invention adopts the simple design structure and good processability, and the cost is reduced by about 10?^ compared with the conventional method, and good effects are obtained.

Claims

Claim

A magnetic steel for a permanent magnet direct-drive wind power generator, characterized in that the magnetic steel has a rectangular cross section, a through hole is formed in the center thereof, an upper surface is arched, a lower surface is arched, and a side surface includes an upper surface Side, mid side, bottom side.

2 . The magnetic steel of a permanent magnet direct drive wind power generator according to claim 1 , wherein the through hole comprises an upper portion and a lower portion, wherein the upper portion is a rounded platform and the lower portion is a cylinder. body.

3. The magnetic steel of a permanent magnet direct drive wind power generator according to claim 1, wherein the upper surface and the arcuate arc of the lower surface have the same diameter.

4. A permanent magnet direct-drive wind turbine auxiliary machine according to claim 1, wherein said upper side is rectangular.

5. A permanent magnet according to claim 1! The magnetic steel of the display bay spirit motor is characterized in that the middle side is arched.

The lower side is rectangular.

7. A magnetic steel for a permanent magnet direct drive wind power generator according to claim ίίί, characterized in that the surface of the magnetic steel is plated

8. The magnetic steel of a permanent magnet direct drive wind power generator according to claim 1, wherein the permanent magnet material type is sintered neodymium iron boron 42SH; residual magnetism (Br) 1.23~1.29 T; maximum magnetic energy product (BH) max^36MGOe _; intrinsic coercivity (Hcj) 19kOe; temperature coefficient of intrinsic coercivity (Hcj) > -0.55 %/°C (20° (:~ 150°C); bulk magnet sticking The shear strength is >10 MPa at room temperature, the shear strength is >5 Mpa at 120 °C, and the insulation of the bonding layer is >500 Ω.