CN113036965A - Method for reducing magnetic steel eddy current loss of full neodymium iron boron permanent magnet motor at high speed and motor structure - Google Patents
Method for reducing magnetic steel eddy current loss of full neodymium iron boron permanent magnet motor at high speed and motor structure Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 167
- 239000010959 steel Substances 0.000 title claims abstract description 167
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 119
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 32
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 81
- 239000000463 material Substances 0.000 claims abstract description 40
- 230000001360 synchronised effect Effects 0.000 claims description 22
- 238000004804 winding Methods 0.000 claims description 13
- 230000001788 irregular Effects 0.000 claims description 6
- 229910052779 Neodymium Inorganic materials 0.000 claims description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 abstract description 36
- 150000002910 rare earth metals Chemical class 0.000 abstract description 18
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- -1 neodymium iron boron rare earth Chemical class 0.000 description 18
- 230000010349 pulsation Effects 0.000 description 10
- 230000004907 flux Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 230000005347 demagnetization Effects 0.000 description 4
- BGPVFRJUHWVFKM-UHFFFAOYSA-N N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] Chemical compound N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] BGPVFRJUHWVFKM-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 230000005284 excitation Effects 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- 230000011218 segmentation Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007429 general method Methods 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
- H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
- H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
Abstract
The invention discloses a method and a motor structure for reducing magnetic steel eddy current loss of a full-neodymium-iron-boron permanent magnet motor at high speed. The ferrite magnetic steel can be used for replacing or partially replacing neodymium iron boron magnetic steel in the permanent magnet motor or additionally placing the ferrite magnetic steel in a rotor magnetic circuit. According to the permanent magnet motor rotor structure, the consumption of rare earth permanent magnet materials of the motor is effectively reduced through the mixing proportion of the neodymium iron boron and the ferrite, the manufacturing cost is greatly reduced, and the harmonic content of an air gap magnetic field is reduced to the maximum degree. According to the invention, through slotting on the outer surface of the rotor and controlling the position of the radial permanent magnet, the influence of harmonic waves at the stator side on the permanent magnet can be effectively reduced, so that the eddy current loss of the magnetic steel of the motor for the electric vehicle under a high-speed operation condition is reduced, and the efficiency is improved.
Description
Technical Field
The invention relates to the field of design of permanent magnet synchronous motors for electric vehicles, in particular to a method for reducing magnetic steel eddy current loss in a rotor of a neodymium iron boron permanent magnet motor at a high speed.
Technical Field
In recent years, rare earth permanent magnet synchronous motors have been widely used in the new energy automobile industry due to their advantages of high efficiency, high power density, etc. The motor permanent magnet is mostly made of neodymium iron boron materials with high coercive force and residual magnetism, the conductivity is high, the heat resistance is poor, the eddy current loss of the permanent magnet is not large compared with the copper iron loss under most conditions, but for a high-speed and high-power density motor and a motor with a closed structure, the eddy current loss of the neodymium iron boron permanent magnet can cause a rotor part of the motor to generate large temperature rise, even irreversible demagnetization of the permanent magnet can be caused in serious conditions, and the permanent magnet is fatal to the permanent magnet motor. The built-in permanent magnet synchronous motor with the fractional-slot centralized winding has the most serious problem of magnetic steel eddy current loss due to the fact that the built-in permanent magnet synchronous motor has a larger stator slot pitch. The rare earth permanent magnet motor has a series of advantages of high power and torque density, wide speed regulation range, capability of outputting larger torque during starting, high reliability and the like, and is widely applied to new energy electric vehicles. However, in recent years, the price of rare earth materials is greatly increased, so that the cost of the rare earth permanent magnet motor is continuously increased. The design of the rare earth-less permanent magnet motor becomes a research focus. After a permanent magnet material which is low in price and poor in magnetic performance is used, the air gap magnetic field of the motor is serious in distortion, a large amount of harmonic waves are generated during operation, especially under the high-speed operation state of the motor, the torque pulsation is too large, large magnetic steel eddy current loss and iron core loss are generated, the local temperature of the motor is too high, the permanent magnet can be seriously and even generated with an irreversible demagnetization phenomenon, and the permanent magnet motor for the electric vehicle is seriously influenced in safe and stable operation.
For the built-in permanent magnet motor, the most common method for reducing the eddy current loss of rotor magnetic steel is magnetic steel segmentation, namely axial segmentation and circumferential segmentation, but the cost of the motor is increased along with the increase of the number of the segments. In addition, the eddy current loss of the magnetic steel can be reduced by a method of increasing the magnetic circuit reluctance between the stator and the rotor, but the motor torque can be reduced while the magnetic circuit reluctance is increased, so that the performance of the motor is influenced.
Therefore, how to effectively reduce the eddy current loss of the ndfeb magnetic steel on the premise of not influencing the cost and the performance of the motor is a problem to be solved by the technical personnel in the field. Therefore, it is necessary to find a method for reducing the eddy current loss of the magnetic steel.
Disclosure of Invention
The invention aims to provide a method and a motor structure for reducing the eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at high speed, and the method can effectively reduce the eddy current loss of the magnetic steel of the all-neodymium-iron-boron permanent magnet motor by reasonably placing ferrite magnetic steel in a rotor magnetic circuit on the premise of not influencing other performances of the motor, thereby achieving the purposes of improving the temperature rise of the motor and improving the efficiency of the motor. The invention solves the problem of motor cost caused by overhigh price of rare earth permanent magnet material and the problem of local overheating of the motor caused by serious eddy current loss of magnetic steel at high speed, and simultaneously ensures that the motor has high torque output capacity and lower torque pulsation.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for reducing magnetic steel eddy current loss of a full-neodymium-iron-boron permanent magnet motor at high speed utilizes ferrite magnetic steel to replace the whole ferrite magnetic steel to form a ferrite magnet, or partially replaces the neodymium-iron-boron magnetic steel in the motor to form a mixed permanent magnet, or additionally places ferrite in a rotor magnetic circuit to form the mixed permanent magnet.
Preferably, when the replaced hybrid permanent magnet is a strip-shaped hybrid permanent magnet formed by combining one section of neodymium-iron-boron magnetic steel and the other section of ferrite magnetic steel, the ratio of the length of the neodymium-iron-boron magnetic steel to the total length of the strip-shaped hybrid permanent magnet is 40-60%. Aiming at the problems in the prior art, the invention reasonably mixes two permanent magnet materials of neodymium iron boron and ferrite, reduces the using amount of rare earth permanent magnet, improves the distribution condition of the magnetic field in the motor and improves the performance of the motor. The reasonable selection of the mixing proportion greatly helps to improve the torque output capacity and reduce the loss of the motor during high-speed operation.
Preferably, ferrite magnetic steel is connected in series in the d-axis or q-axis magnetic circuit of the motor rotor.
The invention discloses a motor structure for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed.
As a preferred technical scheme, the motor structure for reducing the eddy current loss of the magnetic steel of the full-neodymium-iron-boron permanent magnet motor at high speed is applied to a rotor structure of the permanent magnet motor, a series of combined groove units with the same shape and size and a U-shaped structure and a I-shaped structure are uniformly arranged on a rotor core in the circumferential direction around a central rotating shaft, each group of the U-shaped structure comprises two tangential rectangular grooves, the extending direction of the tangential rectangular grooves of the U-shaped structure is the radial direction of the rotor, a first permanent magnet and a second permanent magnet are embedded in the tangential rectangular grooves to form tangential magnetic steel in a mixed permanent magnet form, two ends of each rectangular groove are provided with irregular air grooves communicated with the rectangular grooves, and the bottom edge of each U-shaped groove is provided with a rectangular air groove; permanent magnets are embedded in each group of the I-shaped structure grooves, and symmetrical horn-shaped air grooves are formed in the two sides of each permanent magnet.
As another preferred technical scheme, the motor structure for reducing the eddy current loss of the magnetic steel of the full-neodymium-iron-boron permanent magnet motor at high speed is applied to a rotor structure of a fractional-slot concentrated winding permanent magnet synchronous motor, a series of combined slot units which are in a one-to-one segmented structure and a V-shaped structure and have the same shape and size are uniformly arranged on a rotor iron core in the circumferential direction around a central rotating shaft, each group of the V-shaped structure comprises two symmetrically arranged bar magnets, each bar magnet is an integral mixed permanent magnet unit formed by combining a neodymium-iron-boron magnet and a ferrite magnet, and two ends of each bar magnet are respectively provided with a special-shaped air slot communicated with the bar magnet; each 'one-to-one' segmented structure comprises two sections of short air grooves which are respectively arranged along the direction of the concentric circle of the central rotating shaft, and the extending direction of each short air groove is the tangential direction of the concentric circle of the central rotating shaft.
As another preferred technical scheme, the motor structure for reducing the eddy current loss of the magnetic steel of the full-neodymium-iron-boron permanent magnet motor at high speed is applied to a rotor of a high-speed permanent magnet synchronous motor for an electric vehicle, and comprises a central rotating shaft and a rotor core, wherein 8 groups of U-shaped and I-shaped structural grooves which are completely the same in shape and size are uniformly arranged on the rotor core in the circumferential direction around the central rotating shaft, a rectangular groove is arranged in the tangential direction of each group of U-shaped structures, a first permanent magnet and a second permanent magnet are embedded in the grooves, irregular air grooves communicated with the rectangular grooves are arranged on the upper side and the lower side of each rectangular groove, and rectangular air grooves are arranged on the bottom edges of the U-shaped; permanent magnets are embedded in each group of the I-shaped structural grooves, and symmetrical horn-shaped air grooves are formed in the two sides of each permanent magnet; and symmetrical arc grooves are formed in the side, corresponding to the outer surface of the rotor, of the one-shaped groove structure.
Preferably, "U" type structure groove is close to the first permanent magnet material of air gap side for the neodymium iron boron material in to the rectangular channel, and the second permanent magnet material is the ferrite material, first permanent magnet neodymium accounts for "U" type structure's tangential rectangular channel length proportion X% and is: 60% +/-1%, and the second permanent magnet accounts for 1-X% of the total weight of the magnet: 40% ± 1.
Preferably, the ox horn-shaped air slot comprises an outer circular arc and an inner circular arc, the outer circular arc and the inner circular arc are parallel, and the ratio of the vertical length of the ox horn-shaped air slot to the distance from the end part of the ox horn-shaped air slot to the outer surface of the rotor is as follows: 5.2-6.2:1.
Preferably, the number of the arc-shaped grooves is 2, and the left side and the right side of a perpendicular bisector of a third permanent magnet arranged in the one-shaped groove structure are symmetrically distributed; the included angle between the middle point of the arc-shaped slot and the perpendicular bisector of the third permanent magnet is alpha, and the alpha included angle is 4-5.5 degrees.
Compared with the prior art, the invention has the following obvious prominent substantive characteristics and obvious advantages:
1. according to the invention, the ferrite magnetic steel is reasonably placed in the magnetic circuit of the rotor of the neodymium iron boron rare earth permanent magnet motor, so that the magnetic flux path in the rotor is changed, and the eddy current loss of the neodymium iron boron magnetic steel is reduced; the reasonable selection of the mixing proportion, the arrangement position of the permanent magnet, the length and the size of the magnetic isolation bridge and the slotting position on the outer surface of the rotor greatly helps to improve the torque output capacity and reduce the loss of the motor during high-speed operation;
2. when the neodymium iron boron rare earth magnetic steel is directly replaced by the ferrite magnetic steel, the using amount of the rare earth permanent magnet is reduced, and the cost of the motor is reduced;
3. according to the invention, the ferrite magnetic steel is additionally arranged in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, which is equivalent to the extra increase of the consumption of the non-rare earth permanent magnet, and the ferrite magnetic steel can be used as an auxiliary excitation source of the permanent magnet motor, thereby being beneficial to the improvement of the torque output capability of the motor;
4. according to the invention, the ferrite is reasonably arranged in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, and different electromagnetic properties of the ferrite magnetic steel and the neodymium iron boron magnetic steel can be utilized to be arranged according to a certain rule so as to generate a relatively sinusoidal air gap magnetic field, enhance the fundamental wave content, weaken higher harmonics, inhibit torque pulsation, reduce the eddy current loss of the magnetic steel, improve the motor efficiency and improve the rotor temperature rise;
5. the invention can well solve the problem of larger eddy current loss of the magnetic steel of the neodymium iron boron permanent magnet synchronous motor at high speed on the premise of not damaging the torque output performance of the motor basically by reasonably placing the ferrite magnetic steel in the magnetic circuit of the rotor of the neodymium iron boron rare earth permanent magnet motor.
Drawings
The invention provides two embodiments of fractional slot concentrated winding type neodymium iron boron permanent magnet synchronous motors by combining with the attached drawings, and according to the method in the claim, the eddy current loss of the neodymium iron boron magnetic steel in the motor rotor is effectively reduced by reasonably placing the ferrite magnetic steel in the magnetic circuit of the motor rotor. A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description.
Fig. 1 is a schematic structural view of a part of a rotor of an all-neodymium-iron-boron permanent magnet motor according to a third embodiment of the present invention.
Fig. 2 is a unit structure diagram of a rotor magnetic circuit with ferrite magnetic steel placed therein according to a third embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating eddy current loss comparison of ndfeb magnetic steel according to a third embodiment of the present invention.
Fig. 4 is a schematic structural view of a part of a rotor of an all-neodymium-iron-boron permanent magnet motor according to a fourth embodiment of the present invention.
Fig. 5 is a unit structure diagram of a rotor magnetic circuit with ferrite magnetic steel placed therein according to a fourth embodiment of the present invention.
Fig. 6 is a schematic diagram illustrating eddy current loss comparison of ndfeb magnetic steel according to the fourth embodiment of the present invention.
Fig. 7 is a schematic structural diagram of a motor rotor according to a fifth embodiment of the present invention.
Fig. 8 is a partial dimension labeled diagram of a motor rotor of a fifth embodiment of the invention. The length of the h11- 'one' type permanent magnet, the distance from the end of the h12- 'one' type structure ox horn type air groove to the outer surface of the rotor, the vertical length of the h22- 'one' type structure ox horn type air groove, the proportion of the X% -first permanent magnet in the tangential rectangular groove, and the alpha is the included angle between the middle point of the arc-shaped grooving and the perpendicular bisector of the 'one' type structure ox horn type air groove.
Fig. 9 shows the magnetizing direction diagrams of the motor rotor and the permanent magnets according to the fifth embodiment of the present invention.
It is to be noted, however, that the appended drawings illustrate rather than limit the invention.
Detailed Description
In order that the present disclosure may be more clearly and readily understood, reference will now be made in detail to the present disclosure as illustrated in the accompanying drawings and two specific embodiments. The following embodiments provide a general method for reducing eddy current loss of neodymium iron boron magnetic steel of a neodymium iron boron rare earth permanent magnet motor, especially a fractional slot concentrated winding type permanent magnet synchronous motor.
The invention will be further described with reference to preferred embodiments in conjunction with the accompanying drawings.
Example one
In this embodiment, a method for reducing eddy current loss of magnetic steel of an all-ndfeb permanent magnet motor at a high speed utilizes ferrite magnetic steel to replace all of the ferrite magnetic steel to form a ferrite magnet, or partially replaces the ndfeb magnetic steel in the motor to form a hybrid permanent magnet, or additionally places ferrite in a rotor magnetic circuit to form the hybrid permanent magnet.
The technical problem to be solved by the method of the embodiment is to provide a method for effectively reducing the magnetic steel eddy current loss in the full-neodymium-iron-boron permanent magnet motor by reasonably placing ferrite magnetic steel in a rotor magnetic circuit on the premise of not influencing other performances of the motor, thereby achieving the purposes of improving the motor temperature rise and improving the motor efficiency. In the method, the ferrite magnetic steel is reasonably arranged in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, and the number, the shape and the position of the ferrite magnetic steel are not limited. The method can effectively reduce the eddy current loss of the neodymium iron boron magnetic steel on the premise of not influencing the cost and the performance of the motor, and is favorable for improving the torque output capacity of the motor.
Example two
This embodiment is substantially the same as the first embodiment, and is characterized in that:
in this embodiment, when the replaced hybrid permanent magnet is a bar-shaped hybrid permanent magnet formed by combining one section of ndfeb magnet steel and another section of ferrite magnet steel, the ratio of the length of the ndfeb magnet steel to the total length of the bar-shaped hybrid permanent magnet is 40-60%.
The permanent magnets of the present embodiment are preferably rectangular in shape, so that the percentage of the ndfeb magnet in the mixed magnet structure can be defined as the ratio of the length of the ndfeb magnet to the total length of the ndfeb magnet and the ferrite magnet, and in order to ensure the torque output capability and the sine degree of the air gap flux density of the permanent magnet synchronous motor with the mixed magnet rotor structure, the percentage of the length of the ndfeb magnet in the mixed permanent magnet structure is in the range of 40% -60%. The embodiment reasonably places the ferrite magnetic steel in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, and reasonably replaces or partially replaces the neodymium iron boron magnetic steel in the motor rotor or additionally places the ferrite magnetic steel in the rotor magnetic circuit by analyzing the eddy current loss distribution of the neodymium iron boron magnetic steel in the motor or the magnetic flux path in the rotor.
In the embodiment, ferrite magnetic steel is connected in series in a d-axis or q-axis magnetic circuit of the motor rotor.
In the embodiment, the ferrite magnetic steel is reasonably arranged in the magnetic circuit of the rotor of the neodymium iron boron rare earth permanent magnet motor, so that the magnetic flux path in the rotor is changed, and the eddy current loss of the neodymium iron boron magnetic steel is reduced; when the embodiment adopts the ferrite magnetic steel to directly replace the neodymium iron boron rare earth magnetic steel, the using amount of the rare earth permanent magnet is reduced, and the cost of the motor is reduced.
EXAMPLE III
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, referring to fig. 1 to 3, a motor structure for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed is formed by using the method for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed according to the first embodiment.
In this embodiment, a motor structure for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at high speed is applied to a rotor structure of the permanent magnet motor, a series of combined groove units of a U-shaped structure and a linear structure with the same shape and size are uniformly arranged on a rotor core around a central rotating shaft in the circumferential direction, each group of U-shaped structure comprises two tangential rectangular grooves 2, the extending direction of the tangential rectangular grooves of the U-shaped structure is the radial direction of the rotor, a first permanent magnet 2.1 and a second permanent magnet 2.2 are embedded in the tangential rectangular grooves 2 to form tangential magnetic steel in a mixed permanent magnet form, irregular air grooves 6 communicated with the rectangular grooves are arranged at two ends of each rectangular groove 2, and rectangular air grooves 3 are arranged at the bottom edges of the U-shaped grooves; permanent magnets 1 are embedded in each group of the I-shaped structural grooves, and symmetrical horn-shaped air grooves 7 are arranged on two sides of each permanent magnet.
The embodiment provides a universal method for reducing eddy current loss of neodymium iron boron magnetic steel for a neodymium iron boron rare earth permanent magnet motor, particularly for a fractional slot concentrated winding type permanent magnet synchronous motor. In order to illustrate the effectiveness of the method of the embodiment, a structure diagram of a rotor of a fractional-slot concentrated winding permanent magnet synchronous motor is exemplarily given as shown in fig. 1. The permanent magnet in the fractional slot concentrated winding motor rotor is made of rare earth permanent magnet material neodymium iron boron.
In the motor structure shown in fig. 1, an air slot with large magnetic resistance is positioned on a d-axis magnetic circuit of the rotor, a magnetic chain in an air gap forms a d-axis passage through radial neodymium iron boron magnetic steel and tangential neodymium iron boron magnetic steel after entering the rotor, and the eddy current of the neodymium iron boron magnetic steel is large when the motor runs at high speed. Along with the increase of the rotating speed of the motor, the eddy current loss generated in the neodymium iron boron magnetic steel is increased, and the proportion of the eddy current loss in the tangential neodymium iron boron magnetic steel is gradually increased along with the increase of the rotating speed. The motor rotor has poor heat dissipation conditions, and higher temperature rise of the rotor can be caused by larger eddy current loss. Because the performance of the permanent magnet material is related to the temperature, especially for the neodymium iron boron material with lower Curie point, higher conductivity and larger temperature coefficient, the performance of the neodymium iron boron permanent magnet motor can be reduced by overhigh temperature, and even the demagnetization of the magnetic steel is caused to damage the motor.
Based on the motor structure of the embodiment of the method of the invention, the embodiment reasonably places the ferrite magnetic steel on the rotor magnetic path to effectively solve the problem of overlarge eddy current loss of the neodymium iron boron magnetic steel of the motor in the figure 1 at high speed. The specific embodiment is shown in fig. 2. Fig. 2 shows a partial rotor structure of a permanent magnet motor improved by the motor of fig. 1 by adopting the method of the invention. As shown in fig. 2, ferrite magnetic steel is placed in the air slots of the motor rotor shown in fig. 1, and the ferrite magnetic steel is used to replace part of the tangential ndfeb magnetic steel in the motor rotor shown in fig. 1. As shown in fig. 2, the ferrite magnetic steel is placed in an air slot on the magnetic circuit of the d-axis of the rotor and is connected with the radial neodymium iron boron magnetic steel in series. Compared with the motor shown in the figure 1, when the motor runs under load, part of the flux linkage entering the rotor from the air gap changes the path, and the radial neodymium iron boron magnetic steel passes through ferrite in the air groove on the d shaft, so that the eddy current loss of the radial neodymium iron boron magnetic steel is effectively reduced. As shown in FIG. 2, the rotor structure of the motor has tangential magnetic steel composed of Nd-Fe-B and ferrite. In this embodiment, the ratio of ferrite magnets to tangential magnets affects the performance of the motor. Theoretically, the proportion of ferrite magnetic steel is increased, the consumption of neodymium iron boron rare earth permanent magnet is reduced, the motor cost is greatly reduced, meanwhile, the eddy current loss on the tangential neodymium iron boron magnetic steel is effectively reduced, but the flux density saturation degree of the rotor can be reduced due to the fact that the consumption of the neodymium iron boron magnetic steel is too small, and the torque output capacity of the motor is affected. The neodymium iron boron magnetic steel length that this embodiment adopted accounts for than being 40%, has effectively reduced neodymium iron boron magnetic steel's eddy current loss, promotes the reluctance torque through optimal design simultaneously and accounts for than, has kept the torque output performance of motor basically.
Fig. 3 shows a comparison of ndfeb eddy current losses in the motor of fig. 1 and fig. 2 with a sine wave supply, i.e. without taking into account the current time harmonics. The solid line is the eddy current loss of the ndfeb magnet at different rotation speeds of the full ndfeb motor shown in fig. 1, and the dotted line is the eddy current loss of the ndfeb magnet at different rotation speeds of the motor after the ferrite magnet is placed in the magnetic circuit of the rotor shown in fig. 2. Fig. 3 shows that, according to this embodiment, the ferrite magnetic steel is reasonably placed in the magnetic circuit of the rotor of the full-ndfeb permanent magnet motor, so that the eddy current loss of the ndfeb magnetic steel, especially the eddy current loss of the ndfeb magnetic steel of the fractional slot concentrated winding permanent magnet synchronous motor at a high speed, can be effectively reduced.
In the embodiment, the ferrite magnetic steel is additionally arranged in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, which is equivalent to the extra increase of the consumption of the non-rare earth permanent magnet, and the ferrite magnetic steel can be used as an auxiliary excitation source of the permanent magnet motor, thereby being beneficial to the improvement of the torque output capability of the motor; in the embodiment, the ferrite is reasonably arranged in the magnetic circuit of the rotor of the neodymium iron boron rare earth permanent magnet motor, and the ferrite magnetic steel and the neodymium iron boron magnetic steel can be distributed according to a certain rule by utilizing different electromagnetic properties of the ferrite magnetic steel and the neodymium iron boron magnetic steel so as to generate a relatively sinusoidal air gap magnetic field, enhance the fundamental wave content, weaken higher harmonics, inhibit torque pulsation, reduce the eddy current loss of the magnetic steel, improve the efficiency of the motor and improve the temperature rise of the rotor; the embodiment reasonably places the ferrite magnetic steel in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, and can well solve the problem of large eddy current loss of the magnetic steel at high speed of the neodymium iron boron permanent magnet synchronous motor on the premise of not damaging the torque output performance of the motor basically.
Example four
The present embodiment is basically the same as the third embodiment, and the features are as follows:
in this embodiment, referring to fig. 4-6, a motor structure for reducing eddy current loss of magnetic steel of an all-ndfeb permanent magnet motor at a high speed is formed by using the method for reducing eddy current loss of magnetic steel of an all-ndfeb permanent magnet motor at a high speed according to the first embodiment.
In this embodiment, a motor structure for reducing the eddy current loss of magnetic steel of a full-neodymium-iron-boron permanent magnet motor at high speed is applied to a rotor structure of a fractional-slot concentrated winding permanent magnet motor, a series of combined slot units of an one-to-one segmented structure and a V-shaped structure which are same in shape and size are uniformly arranged on a rotor core in the circumferential direction around a central rotating shaft, wherein each group of the V-shaped structure 4 comprises two symmetrically arranged bar magnets 4, each bar magnet 4 is an integral mixed permanent magnet unit formed by combining a neodymium-iron-boron magnet 4.1 and a ferrite magnet 4.2, and two ends of each bar magnet 4 are respectively provided with a special-shaped air slot communicated with the bar magnet 4; each one-to-one segmented structure comprises two sections of short air grooves 5 which are respectively arranged along the direction of the concentric circle of the central rotating shaft, and the extending direction of each short air groove 5 is the tangential direction of the concentric circle of the central rotating shaft.
In order to further illustrate the universality of the method of the present invention, as shown in fig. 4, the present embodiment provides another fractional-slot concentrated winding permanent magnet synchronous motor rotor structure with a different rotor structure. The permanent magnet in the fractional slot concentrated winding motor rotor is made of rare earth permanent magnet material neodymium iron boron. The amount of the permanent magnet of the motor shown in fig. 4 is equal to that of the permanent magnet of the motor shown in fig. 1, and because the volume of the single permanent magnet of the motor shown in fig. 4 is large, the eddy current loss on the neodymium iron boron magnetic steel is large when the rotating speed is increased. Based on the motor structure of the embodiment of the method, the ferrite magnetic steel is reasonably placed on the rotor magnetic path of the motor so as to effectively solve the problem of overlarge eddy current loss of the neodymium iron boron magnetic steel of the motor in the figure 4 at high speed. A specific embodiment is shown in fig. 5.
Fig. 5 shows a partial rotor structure of a permanent magnet machine improved by the method according to the invention based on the embodiment shown in fig. 4. As shown in fig. 5, ferrite magnetic steel is used to replace part of the ndfeb magnetic steel in the rotor of the motor shown in fig. 4. As shown in fig. 5, the permanent magnet of the rotor structure of the motor is composed of ndfeb and ferrite. In order to ensure the torque output capacity and the sine level of the air gap flux density, the percentage of the neodymium iron boron magnetic steel adopted by the embodiment is 60%, and the eddy current loss of the neodymium iron boron magnetic steel is effectively reduced.
Fig. 6 shows a comparison of ndfeb eddy current losses in the motor of fig. 4 and 5 with a sine wave supply, i.e. without taking into account the current time harmonics. The solid line shows the eddy current loss of the ndfeb magnet at different rotation speeds of the full ndfeb motor shown in fig. 4, and the dotted line shows the eddy current loss of the ndfeb magnet at different rotation speeds of the motor after the ferrite magnet is introduced into the magnetic circuit of the rotor shown in fig. 5. Fig. 6 shows that according to the invention, the ferrite magnetic steel is reasonably arranged in the magnetic circuit of the rotor of the full-ndfeb permanent magnet motor, so that the eddy current loss of the ndfeb magnetic steel can be effectively reduced, especially the eddy current loss of the ndfeb magnetic steel of the fractional-slot concentrated winding permanent magnet synchronous motor at a high speed.
In the embodiment, the ferrite magnetic steel is additionally arranged in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, which is equivalent to the extra increase of the consumption of the non-rare earth permanent magnet, and the ferrite magnetic steel can be used as an auxiliary excitation source of the permanent magnet motor, thereby being beneficial to the improvement of the torque output capability of the motor; in the embodiment, the ferrite is reasonably arranged in the magnetic circuit of the rotor of the neodymium iron boron rare earth permanent magnet motor, and the ferrite magnetic steel and the neodymium iron boron magnetic steel can be distributed according to a certain rule by utilizing different electromagnetic properties of the ferrite magnetic steel and the neodymium iron boron magnetic steel so as to generate a relatively sinusoidal air gap magnetic field, enhance the fundamental wave content, weaken higher harmonics, inhibit torque pulsation, reduce the eddy current loss of the magnetic steel, improve the efficiency of the motor and improve the temperature rise of the rotor; the embodiment reasonably places the ferrite magnetic steel in the rotor magnetic circuit of the neodymium iron boron rare earth permanent magnet motor, and can well solve the problem of large eddy current loss of the magnetic steel at high speed of the neodymium iron boron permanent magnet synchronous motor on the premise of not damaging the torque output performance of the motor basically.
EXAMPLE five
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, referring to fig. 7 to 9, a motor structure for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed is formed by using the method for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed according to the first embodiment.
In this embodiment, a motor structure for reducing magnetic steel eddy current loss of a full-neodymium-iron-boron permanent magnet motor at a high speed is applied to a rotor of a high-speed permanent magnet synchronous motor for an electric vehicle, and comprises a central rotating shaft and a rotor core, wherein 8 groups of U-shaped and I-shaped structure grooves with completely identical shapes and sizes are uniformly arranged on the rotor core around the central rotating shaft in the circumferential direction, a rectangular groove 2 is arranged in the tangential direction of each group of U-shaped structures, a first permanent magnet 2.1 and a second permanent magnet 2.2 are embedded in the grooves, irregular air grooves 6 communicated with the rectangular grooves 2 are respectively arranged on the upper side and the lower side of each rectangular groove 2, and rectangular air grooves 3 are arranged on the bottom edges of the; permanent magnets 1 are embedded in each group of the one-shaped structure grooves, and symmetrical horn-shaped air grooves 7 are formed in the two sides of each permanent magnet; and a symmetrical arc-shaped groove 8 is formed in the side of the one-shaped groove structure, which corresponds to the outer surface of the rotor.
The motor cost problem that leads to because of the tombarthite permanent magnet material price is too high is solved to this embodiment to and the local overheat problem of motor that leads to seriously to magnet steel eddy current loss under the high speed, guarantee simultaneously that the motor has the moment pulsation of high torque output ability and lower commentaries on classics. This embodiment high-speed PMSM rotor structure for electric motor car, this rotor structure not only can reduce tombarthite permanent magnet material quantity, can improve reluctance torque moreover, reduce magnet steel eddy current loss under the high speed, reduce the torque pulsation, effectively promote the motor price/performance ratio.
EXAMPLE six
This embodiment is substantially the same as the above embodiment, and is characterized in that:
referring to fig. 8, the material of the first permanent magnet 2.1 on the side close to the air gap in the rectangular grooves on the two sides of the U-shaped structure is neodymium iron boron, the material of the second permanent magnet 2.1 is ferrite, the proportion of the first permanent magnet 2.1 in the rectangular grooves on one side of the U-shaped structure is 60%, and the proportion of the second permanent magnet 2.1 in the rectangular grooves on one side of the U-shaped structure is 40%. The permanent magnet material embedded in the rectangular groove of the I-shaped structure is neodymium iron boron, and the length h11 of the permanent magnet material is 20 mm. The vertical length h22 of the ox horn air slot 7 is 6mm, and the distance h12 from the end to the outer surface of the rotor is 1 mm. The number of the arc-shaped slots 8 is 2, and the arc-shaped slots are symmetrically distributed on the left side and the right side of the perpendicular bisector of the permanent magnet with the one-shaped structure. The included angle alpha is: 5.4 degrees.
Referring to the attached figure 9 of the specification, the U-shaped permanent magnet adopts tangential magnetization, and the I-shaped permanent magnet adopts radial magnetization and forms a series magnetic circuit with the U-shaped permanent magnet.
In the rotor structure of this embodiment, "U" type structure tangential adopts neodymium iron boron material proportion 60% to add ferrite 40% mixed form, and the rectangular channel is close to the air gap side and adopts neodymium iron boron material, can effectively increase straight axle magnetic circuit saturation degree, and then strengthens the air gap flux density between both sides permanent magnet to radial "one" type structure permanent magnet, has guaranteed the motor performance, and the neodymium iron boron material that magnetic property is stronger simultaneously can effectively resist the demagnetization phenomenon that the armature reflection leads to. The residual 40% of the rectangular groove is made of ferrite material with low price, so that the cost of the motor can be greatly reduced while the magnetic performance is ensured, and in addition, the influence of magnetic steel eddy current loss can be further reduced due to lower conductivity under the high-speed running condition of the electric vehicle.
Due to the magnetic adjustment effect of the stator slots, higher harmonics are inevitably generated in the magnetic field passing by the 'one' type neodymium iron boron close to the air gap. Because the conductivity of the neodymium iron boron material is very high, larger eddy current loss is generated. Increase ox horn type groove vertical length to increase "one" type neodymium iron boron materials to the distance between the air gap, can reduce the higher harmonic to the permanent magnet influence, effectively reduce magnet steel eddy current loss, promote motor efficiency. Meanwhile, the distance from the end part of the horn-shaped groove to the outer surface of the rotor is ensured, magnetic leakage can be inhibited, and the torque characteristic of the motor is improved. Further, the rotor outer surface slotting can be equivalently understood as the number of stator teeth is increased, so that additional cogging torque is generated, and components on certain harmonics can be mutually offset with the cogging torque before slotting, so that the cogging torque and the torque ripple are reduced. However, any slotting can not guarantee that the cogging torque is reduced to a certain extent, and the invention optimizes symmetrical double-arc slotting and slotting positions, so that the case proves that the torque ripple can be effectively reduced, and the running stability of the motor is improved.
To sum up, the high-speed permanent magnet synchronous motor rotor for an electric vehicle of the above embodiment includes 8 groups of U-shaped and i-shaped structural grooves which are uniformly arranged on a rotor core in the circumferential direction around a central rotating shaft and have the same shape and size, wherein the tangential direction of the U-shaped structural grooves adopts a mixed form of neodymium iron boron material with a proportion of 60% and ferrite with a proportion of 40%; each group of radial one-shaped structures is provided with symmetrical arc grooves corresponding to the outer surface of the rotor. According to the permanent magnet motor rotor structure provided by the embodiment, through the mixing proportion form of 60% of neodymium iron boron and 40% of ferrite, the use amount of rare earth permanent magnet materials of the motor is effectively reduced, the manufacturing cost is greatly reduced, and meanwhile, the harmonic content of an air gap magnetic field is reduced to the maximum extent. Furthermore, the outer surface of the rotor is grooved and the position of the radial linear permanent magnet is controlled, so that the influence of the harmonic waves at the stator side on the permanent magnet can be effectively reduced, the eddy current loss of the magnetic steel of the motor for the electric vehicle under the high-speed running condition is reduced, and the efficiency is improved. The permanent magnet motor rotor structure provided by the embodiment effectively reduces the using amount of rare earth permanent magnet materials of the motor, greatly reduces the manufacturing cost and simultaneously reduces the harmonic content of an air gap magnetic field to the maximum extent by a mixing proportion form of 60% of neodymium iron boron and 40% of ferrite. Furthermore, the outer surface of the rotor is grooved and the position of the radial linear permanent magnet is controlled, so that the influence of the harmonic waves at the stator side on the permanent magnet can be effectively reduced, the eddy current loss of the magnetic steel of the motor for the electric vehicle under the high-speed running condition is reduced, and the efficiency is improved.
In addition, neodymium iron boron materials are adopted above the tangential rectangular grooves of the U-shaped structure in the preferred embodiment of the invention, and the proportion of X% of the dosage is 40%. The material proportion effectively increases the saturation degree of a direct-axis magnetic circuit, further enhances the air gap flux density between permanent magnets on two sides and permanent magnets with a radial 'one' type structure, improves the magnetic field distribution in the motor, increases the difference value of the quadrature-direct axis inductance, and further effectively improves the reluctance torque of the motor. Meanwhile, the neodymium iron boron reduces the distortion of an air gap magnetic field to the maximum extent and inhibits harmonic waves and torque pulsation, and particularly under the condition of high-speed running of an electric vehicle, the proportion effect of the preferred embodiment of the invention is extremely obvious; the ferrite material is adopted below, the dosage proportion is 1-X% and is 60%, the material proportion can effectively reduce the dosage of the rare earth permanent magnet material, the motor cost is greatly reduced, meanwhile, the ferrite material has lower conductivity, and the magnetic steel eddy current loss generated by harmonic waves can be further reduced under the high-speed operation condition.
In addition, the ratio of the vertical length h22 of the ox horn-shaped air slot at two sides of the radial 'one' type structure of the preferred embodiment of the invention to the distance h12 from the radial 'one' type structure to the outer surface of the rotor is as follows: 5.2-6.2:1, and the length of the ox horn-shaped air slot is reasonably designed to effectively inhibit magnetic leakage and improve the torque output capability of the motor. Meanwhile, the distance between the neodymium iron boron with the one-shaped structure and the air gap is changed, the influence of the stator magnetic field harmonic waves on the magnetic steel is effectively reduced, and the eddy current loss of the magnetic steel is reduced.
In addition, the included angle alpha between the middle point of the arc-shaped slot on the outer side of the motor rotor and the perpendicular bisector of the 'one' type structure is 4-5.5 degrees. The slotting on the outer surface of the rotor can generate additional cogging torque, the cogging torque generated by slotting the stator can be offset in a certain range, the torque pulsation is effectively reduced, and the running stability of the motor is improved.
Furthermore, it should be noted that, unless otherwise specified or indicated, the terms "radial direction" and "tangential direction" in the description refer to the magnetization direction of the magnetic steel in the rotor and are only used for different components in the description of the embodiment, but the application of the present invention is not limited to only radial and tangential permanent magnets, but is applicable to any magnetic steel arrangement of the motor structure. The extension direction of the tangential rectangular groove of the U-shaped structure of the preferred embodiment is the radial direction of the rotor. In conclusion, the invention provides a high-speed permanent magnet synchronous motor rotor structure for an electric vehicle, which not only can reduce the consumption of rare earth permanent magnet materials, but also can improve reluctance torque, reduce magnetic steel eddy current loss at high speed, reduce torque pulsation and effectively improve the cost performance of the motor.
The above embodiments of the present invention provide a general method for reducing eddy current loss of ndfeb magnetic steel, and the above is only a preferred embodiment of the present invention. It will be understood that while the present invention has been described in connection with the preferred embodiment, it is not intended to limit the invention to that embodiment. It will be apparent to any person skilled in the art that changes and modifications are possible using the teachings disclosed above without departing from the scope of the inventive concept. Therefore, any simple modification and deformation application of the above embodiments according to the theoretical principle of the present invention, without departing from the technical scheme of the present invention for placing ferrite magnetic steel in the rotor to reduce the eddy current loss of the neodymium iron boron magnetic steel of the permanent magnet motor, still fall within the protection scope of the technical scheme of the present invention.
Claims (10)
1. A method for reducing magnetic steel eddy current loss of a full-neodymium-iron-boron permanent magnet motor at a high speed is characterized by comprising the following steps: and the ferrite magnetic steel is completely replaced to form a ferrite magnet, or the neodymium iron boron magnetic steel in the motor is partially replaced to form a mixed permanent magnet, or the ferrite is additionally placed in a rotor magnetic circuit to form the mixed permanent magnet.
2. The method of reducing magnetic steel eddy current loss at high speed of an all-neodymium-iron-boron permanent magnet motor according to claim 1, wherein the method comprises the following steps: when the replaced mixed permanent magnet is a strip-shaped mixed permanent magnet formed by combining one section of neodymium-iron-boron magnetic steel and the other section of ferrite magnetic steel, the ratio of the length of the neodymium-iron-boron magnetic steel to the total length of the strip-shaped mixed permanent magnet is 40-60%.
3. The method of reducing magnetic steel eddy current loss at high speed of an all-neodymium-iron-boron permanent magnet motor according to claim 1, wherein the method comprises the following steps: the ferrite magnetic steel is connected in series in a d-axis or q-axis magnetic circuit of the motor rotor.
4. The utility model provides a reduce motor structure of magnet steel eddy current loss under full neodymium iron boron permanent-magnet machine is high-speed which characterized in that: the method of reducing magnetic steel eddy current loss at high speed of an all-ndfeb permanent magnet machine according to claim 1 is used to form a magnet structure.
5. The motor structure for reducing magnetic steel eddy current loss of the all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 4, is characterized in that: the rotor structure is applied to a permanent magnet motor, a series of combined groove units of U-shaped structures and I-shaped structures with the same shape and size are uniformly arranged on a rotor core in the circumferential direction around a central rotating shaft, each group of U-shaped structures comprises two tangential rectangular grooves (2), the extending direction of the tangential rectangular grooves of the U-shaped structures is the radial direction of the rotor, a first permanent magnet (2.1) and a second permanent magnet (2.2) are embedded in the tangential rectangular grooves (2) to form tangential magnetic steel in a mixed permanent magnet form, irregular air grooves (6) communicated with the rectangular grooves are formed in two ends of each rectangular groove (2), and rectangular air grooves (3) are formed in the bottom edges of the U-shaped grooves; permanent magnets (1) are embedded in each group of the I-shaped structural grooves, and symmetrical horn-shaped air grooves (7) are arranged on two sides of each permanent magnet.
6. The motor structure for reducing magnetic steel eddy current loss of the all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 4, is characterized in that: the permanent magnet synchronous motor rotor structure is applied to a fractional slot concentrated winding, a series of combined slot units which are in the shape of one-to-one segmented structures and V-shaped structures are uniformly arranged on a rotor core around a central rotating shaft in the circumferential direction, the size of each combined slot unit is the same, each group of V-shaped structures (4) comprises two symmetrically arranged bar magnets (4), each bar magnet (4) is an integral mixed permanent magnet unit formed by combining a neodymium iron boron magnet (4.1) and a ferrite magnet (4.2), and two ends of each bar magnet (4) are respectively provided with a special-shaped air slot communicated with the bar magnets; each 'one-to-one' segmented structure comprises two sections of short air grooves (5) which are respectively arranged along the direction of the concentric circle of the central rotating shaft, and the extending direction of each short air groove (5) is the tangential direction of the concentric circle of the central rotating shaft.
7. The motor structure for reducing magnetic steel eddy current loss of the all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 4, is characterized in that: the rotor applied to the high-speed permanent magnet synchronous motor for the electric vehicle comprises a central rotating shaft and a rotor core, wherein 8 groups of U-shaped and I-shaped structure grooves which are completely the same in shape and size are uniformly arranged on the rotor core around the central rotating shaft in the circumferential direction, a rectangular groove (2) is arranged in the tangential direction of each group of U-shaped structures, a first permanent magnet (2.1) and a second permanent magnet (2.2) are embedded in the groove, irregular air grooves (6) communicated with the rectangular groove (2) are formed in the upper side and the lower side of the rectangular groove (2), and a rectangular air groove (3) is formed in the bottom edge of the U-shaped groove; permanent magnets (1) are embedded in each group of the one-shaped structure grooves, and symmetrical horn-shaped air grooves (7) are arranged on the two sides of each permanent magnet; the side of the one-shaped groove structure corresponding to the outer surface of the rotor is provided with a symmetrical arc-shaped groove (8).
8. The motor structure for reducing eddy current loss of magnetic steel of an all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 7, wherein the material of the first permanent magnet (2.1) close to the air gap side in the rectangular groove (3) in the U-shaped structural groove is neodymium-iron-boron material, the material of the second permanent magnet (2.2) is ferrite material, and the tangential rectangular groove length ratio X% of the first permanent magnet neodymium (2.1) in the U-shaped structure is as follows: 60% +/-1%, and the second permanent magnet (5) accounts for 1-X% of the total weight of the magnet: 40% ± 1.
9. The motor structure for reducing magnetic steel eddy current loss of an all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 7, is characterized in that: ox horn type air tank contains outside circular arc and inboard circular arc, and the inside and outside circular arc is parallel, and the perpendicular length of ox horn type air tank is rather than tip to rotor surface distance ratio: 5.2-6.2:1.
10. The motor structure for reducing magnetic steel eddy current loss of an all-neodymium-iron-boron permanent magnet motor at a high speed according to claim 7, is characterized in that: the number of the arc-shaped grooves is 2, and the left side and the right side of a perpendicular bisector of a third permanent magnet (1) arranged in the one-shaped groove structure are symmetrically distributed; the included angle between the middle point of the arc-shaped slot and the perpendicular bisector of the third permanent magnet (1) is alpha, and the alpha included angle is 4-5.5 degrees.
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