CN111884378A - Electric vehicle permanent magnet motor composite rotor and preparation method thereof - Google Patents

Abstract

The invention discloses a composite rotor of a permanent magnet motor of an electric vehicle, which is characterized by comprising a reluctance section rotor and a permanent magnet section rotor, and specifically comprises a hollow rotor core and a central rotating shaft, wherein the center of the rotor core is provided with a central rotating shaft hole for passing through the central rotating shaft, the rotor core is tightly sleeved on the central rotating shaft of the motor and comprises an outer wall and an inner wall, the end surface of the rotor core is provided with N groups of magnetic steel grooves for inserting permanent magnet monomers, N is an even number, and two permanent magnet monomers are symmetrically embedded in the single group of magnetic steel grooves; permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves, and permanent magnet monomers with opposite polarities are inserted into adjacent groups of magnetic steel grooves. The invention also discloses a preparation method of the composition. According to the invention, through synchronously improving the structure and the preparation process, the material cost is reduced, the performances such as torque density and the like are kept at a higher level, the torque density and the power density of the motor are high, and the irreversible demagnetization resistance is strong.

Description

Electric vehicle permanent magnet motor composite rotor and preparation method thereof

Technical Field

The invention relates to the technical field of permanent magnet motors for new energy electric vehicles, in particular to a composite rotor of a permanent magnet motor of an electric vehicle and a preparation method thereof.

Background

The motor is a device for converting mechanical energy and electric energy, comprises a motor and a generator, is widely applied to a plurality of fields of industry, agriculture, aerospace, traffic, communication, computers, scientific research, office equipment, household appliances, medical equipment, environmental protection machinery and the like, particularly aims at overcoming the shortage of fuel resources and the damage of automobile exhaust emission to the natural environment, and actively strives to research and develop various new energy automobiles in various countries in the world; as a new energy pollution-free zero-emission automobile, the motor becomes a core power driving part and can be used as a generator to recover energy when the automobile is towed backwards.

Based on the characteristics of the electric automobile, the adopted motor has higher requirements, and in order to improve the highest speed, the motor should have higher instantaneous power and power density (W/kg); in order to increase the charging travel distance, the motor should have higher efficiency; moreover, the electric automobile works in a speed-changing way, so that the motor has higher high and low speed comprehensive efficiency; in addition, the device has strong overload capacity, large starting torque and quick torque response. The speed is low when the electric vehicle is started and climbs a slope, but the required moment is large; the torque required for normal operation is small and the speed is high.

At present, the motor of the electric automobile is mainly of three types:

the alternating current motor has the advantages of low efficiency, large volume and weight and poor speed responsiveness.

Secondly, the permanent magnet motor and the permanent magnet synchronous motor have own defects, and the permanent magnet material on the rotor can generate the phenomenon of magnetic decline under the conditions of high temperature, vibration and overcurrent, so that the motor is easy to damage under the relatively complicated working condition; and the price of the permanent magnet material is higher, so the cost of the whole motor and the control system thereof is higher. Permanent magnet synchronous motors are widely used in electric vehicles.

At present, the switched reluctance motor seems to be more consistent with the use requirement of the electric vehicle in various technical characteristics from the mature motor technology, but the vibration and noise problem of the switched reluctance motor is that the electric vehicle, particularly a small passenger vehicle, cannot bear the vibration and noise problem, so the switched reluctance motor is not popularized yet and is only in the test stage on a goods transport vehicle.

In the prior art, chinese patent No. 201710676131.5 discloses a surface-mount motor, a surface-mount motor rotor, and a stator, where a magnetic steel of the surface-mount motor rotor has an outer side surface facing the stator, and both sides of the outer side surface have edge cutting structures symmetrically arranged along a center line thereof. According to the surface-mounted motor rotor provided by the invention, the cutting edge structures symmetrically arranged along the central line of the outer side surface are arranged on the two sides of the outer side surface, so that the length of an air gap of the motor at each position along the inner circle surface of the stator can be changed, an air gap magnetic field is further improved, the air gap flux density and the counter electromotive force waveform sine degree are improved, the harmonic ratio is reduced, the torque pulsation is further reduced, and the vibration noise of the motor is effectively reduced.

However, the prior art still has certain defects, the rare earth in the rare earth permanent magnet brushless motor is large in usage amount, the rare earth material is expensive, and the material cost of the rare earth permanent magnet material is more than half of the total cost of the whole motor material under normal conditions. Moreover, the price fluctuation of the rare earth permanent magnetic material is large, which is not beneficial to the long-term stable cost control of manufacturers. In order to reduce the material cost of the motor, if the using amount of the rare earth permanent magnet is directly reduced, the torque density of the motor can hardly reach the level of the existing permanent magnet brushless direct current motor, and the performance of the motor is reduced.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a composite rotor of a permanent magnet motor of an electric vehicle and a preparation method thereof. Compared with the traditional permanent magnet rotor with a motor surface-mounted structure of an electric vehicle, the rare earth permanent magnet material adopted by the composite rotor and the embedded structure is reduced by more than half, so that the environmental pollution caused by mining rare earth ore can be effectively reduced, in addition, the torque density and the power density of the motor are high, the irreversible demagnetization resistance is strong, and the material cost is greatly reduced.

In order to achieve the purpose, the invention provides the following technical scheme:

the composite rotor of the permanent magnet motor of the electric vehicle is characterized by comprising a reluctance section rotor and a permanent magnet section rotor, and specifically comprises a hollow rotor core and a central rotating shaft, wherein the center of the rotor core is provided with a central rotating shaft hole for passing through the central rotating shaft, the central rotating shaft hole is tightly sleeved on the central rotating shaft of the motor, the rotor core comprises an outer wall and an inner wall, the end surface of the rotor core is provided with N groups of magnetic steel grooves for inserting permanent magnet monomers, N is an even number, and two permanent magnet monomers are symmetrically embedded in the single group of magnetic steel grooves; permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves, and permanent magnet monomers with opposite polarities are inserted into adjacent groups of magnetic steel grooves.

The rotor core structure is provided with a plurality of rotor weight reduction grooves; the rotor lightening slots are arranged between the central rotating shaft and the magnetic steel slots, surround the center of a circle of the rotor iron core and are distributed in central symmetry.

The back electromotive force modification radius of the rotor core is 66.16 mm; the number of poles of the rotor electrode of the rotor core is 8, the included angle between the direct axis of the rotor motor and the quadrature axis of the rotor motor is 22.5 degrees, and the back electromotive force modification center offset distance is 26.13 mm.

The hollow rotor core is formed by laminating rotor punching sheets.

The length of the magnetic steel groove is 9mm, the width of the permanent magnet monomer inserted into the magnetic steel groove is 2.5mm, and the permanent magnet monomers are symmetrically inserted into the magnetic steel groove at an angle of 20 degrees; the included angle of the outer edge of the permanent magnet monomer is 27.3 degrees, and the included angle width of the magnetic bridge is 35.44 degrees.

The permanent magnet monomer is a rare earth permanent magnet monomer or a ferrite permanent magnet monomer.

A preparation method of a composite rotor of a permanent magnet motor of an electric vehicle comprises the following steps:

the method comprises the following steps that firstly, a rotor core of the composite rotor is prepared, the rotor core is of a hollow structure and comprises an outer wall and an inner wall, a central rotating shaft hole for passing through a central rotating shaft is formed in the center of the rotor core, and the rotor core is tightly sleeved on the central rotating shaft;

step two, arranging N groups of magnetic steel slots on the inner wall of the rotor core, wherein N is an even number, every two adjacent magnetic steel slots form a group of magnetic slot pairs, two magnetic steel slots in each group of magnetic slot pairs are arranged in a V shape, the opening direction of the magnetic steel slots faces the outer side of the rotor core, the magnetic slot pairs are distributed around the rotor core in a central symmetry manner, and the two magnetic steel slots in the same group of magnetic slot pairs are symmetrically arranged about a straight line passing through the center of the rotor core;

inserting a rare earth permanent magnet monomer or a ferrite permanent magnet monomer into the magnetic steel groove; rare earth permanent magnet monomers or ferrite permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves, and rare earth permanent magnet monomers or ferrite permanent magnet monomers with opposite polarities are inserted into the adjacent group of magnetic steel grooves.

As a further improvement of the present invention, the first step further comprises the following steps:

step one, setting the back electromotive force modification radius of a rotor iron core structure to be 66.16 mm; when the motor runs, the rotor core structure shapes the stator teeth to enable the counter electromotive force of the motor to be sine wave voltage.

As a further improvement of the present invention, the first step further comprises the following steps:

step two, arranging a plurality of rotor weight reduction grooves on the rotor core structure; the rotor lightening slots are arranged between the central rotating shaft and the magnetic steel slots and are distributed around the center of the rotor iron core in a central symmetry manner.

As a further improvement of the present invention, the second step further comprises the following steps:

and step two, setting the number of pole slots in the rotor core of the motor, and calculating according to motors with different numbers of pole slots so as to obtain the insertion angle of the permanent magnet monomer in the rotor core, the outer edge included angle of the permanent magnet monomer and the included angle of the width of the magnetic bridge.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the composite rotor of the permanent magnet motor of the electric vehicle and the preparation method thereof, provided by the invention, through synchronous improvement of the structure and the preparation process, the use amount of rare earth materials is reduced, the material cost is reduced, and meanwhile, the performances such as the torque density and the like of the motor are kept at a higher level. According to the composite rotor structure provided by the invention, through the improved design, compared with the traditional permanent magnet rotor in the form of surface-mounted motor of the electric vehicle, the adopted rare earth permanent magnet material is reduced by more than half, the material cost is greatly reduced, and the environmental pollution caused by mining rare earth ore can be effectively reduced; meanwhile, the motor after improved design has high torque density and power density, strong irreversible demagnetization resistance and excellent comprehensive performance, and can meet the requirements of high-efficiency driving, flexible speed regulation and the like of a new energy electric vehicle.

(2) According to the composite rotor of the permanent magnet motor of the electric vehicle and the preparation method thereof, the back electromotive force modification radius of the rotor core structure is set to be 66.16mm, and the rotor core structure modifies the stator teeth to enable the back electromotive force of the motor to be sine-wave voltage in the running process of the motor, so that the torque pulsation and the motor noise output by the motor can be effectively reduced, and the output efficiency of the motor is improved.

To more clearly illustrate the structural features and effects of the present invention, the following detailed description is given with reference to specific examples.

Drawings

FIG. 1 is a schematic top-view cross-sectional structure diagram of a composite rotor of a permanent magnet motor of an electric vehicle according to an embodiment of the invention;

fig. 2 is a schematic diagram of the structural design principle of the composite rotor of the permanent magnet motor of the electric vehicle in the embodiment of the invention.

The attached drawings are as follows: 1. a rotor core; 2. a central rotating shaft; 3. a magnetic steel groove; 4. a rotor weight reduction groove; 5. a rotor motor straight shaft; 6. and (4) intersecting the shaft of the rotor motor.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-2, the composite rotor of the permanent magnet motor of the electric vehicle provided by the embodiment is composed of a reluctance section rotor and a permanent magnet section rotor, and specifically includes a hollow rotor core 1 and a central rotating shaft 2, the center of the rotor core 1 is provided with a central rotating shaft hole for passing through the central rotating shaft 2, the central rotating shaft hole is tightly sleeved on the central rotating shaft 2 of the motor, the rotor core 1 includes an outer wall and an inner wall, the end surface of the rotor core 1 is provided with N groups of magnetic steel slots 3 for inserting permanent magnet monomers, N is an even number, and two permanent magnet monomers are symmetrically embedded in the single group of magnetic steel slots 3; rare earth permanent magnet monomers or ferrite permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves 3, and rare earth permanent magnet monomers or ferrite permanent magnet monomers with opposite polarities are inserted into the adjacent group of magnetic steel grooves 3.

In the composite rotor of the permanent magnet motor of the electric vehicle in the embodiment, the rotor core 1 is structurally provided with a plurality of rotor weight reduction grooves 4; the rotor lightening slots 4 are arranged between the central rotating shaft 2 and the magnetic steel slots 3, surround the circle center of the rotor iron core 1 and are distributed in a centrosymmetric manner.

In the composite rotor of the permanent magnet motor of the electric vehicle in the embodiment, the back electromotive force modification radius of the rotor core 1 is set to be 66.16 mm; when the number of poles of the rotor electrode of the rotor core is 8, the included angle between the direct axis of the rotor motor and the quadrature axis of the rotor motor is 22.5 degrees, and the back electromotive force modification center offset distance is 26.13 mm.

The hollow rotor core is formed by laminating rotor punching sheets.

The length of the magnetic steel groove is 9mm, the width of the permanent magnet monomer inserted into the magnetic steel groove is 2.5mm, and the axial lead of each permanent magnet monomer and a horizontal line (or a tangent line) are symmetrically inserted into the magnetic steel groove at an angle of 20 degrees; the included angle of the outer edge of the permanent magnet monomer is 27.3 degrees, and the included angle width of the magnetic bridge is 35.44 degrees.

In the composite rotor of the permanent magnet motor of the electric vehicle in the embodiment, the hollow rotor core 1 is formed by laminating rotor punching sheets.

In the composite rotor of the permanent magnet motor of the electric vehicle in the embodiment, the length of the magnetic steel slot 3 is 9mm, the width of the permanent magnet monomer inserted into the magnetic steel slot 3 is 2.5mm, and the permanent magnet monomer is symmetrically inserted into the magnetic steel slot 3 at an angle of 20 degrees (the included angle between the axis line and the horizontal line or the tangent line); when the pole number of the permanent magnet composite rotor of the electric vehicle is 8, the included angle between the direct axis of the rotor motor and the quadrature axis of the rotor motor is 22.5 degrees, the back electromotive force modification center offset distance is 26.13mm, the included angle of the outer edge of the permanent magnet monomer is 27.3 degrees, and the width of the included angle of the magnetic bridge is 35.44 degrees.

The preparation method of the composite rotor of the permanent magnet motor of the electric vehicle comprises the following steps:

step one, preparing a rotor core 1 of the composite rotor, wherein the rotor core 1 is of a hollow structure and comprises an outer wall and an inner wall, a central rotating shaft hole for passing through a central rotating shaft 2 is formed in the center of the rotor core 1, and the rotor core 1 is tightly sleeved on the central rotating shaft 2;

setting the back electromotive force modification radius of the rotor core 1 structure to be 66.16 mm; when the motor runs, the rotor core 1 structure shapes the stator teeth to make the counter electromotive force of the motor be sine wave voltage;

the rotor core 1 is structurally provided with a plurality of rotor weight reduction grooves 4; the rotor weight reduction slots 4 are arranged between the central rotating shaft 2 and the magnetic steel slots 3 and are distributed around the center of the rotor iron core 1 in a central symmetry manner;

step two, arranging N groups of magnetic steel grooves 3 on the inner wall of the rotor core 1, wherein N is an even number, every two adjacent magnetic steel grooves 3 form a group of magnetic groove pairs, the two magnetic steel grooves 3 in each group of magnetic groove pairs are arranged in a V shape, the opening direction of the magnetic steel grooves faces the outer side of the rotor core 1, the magnetic groove pairs surround the rotor core 1 and are distributed in a central symmetry manner, and the two magnetic steel grooves 3 in the same group of magnetic groove pairs are symmetrically arranged on the basis of a straight line passing through the center of the rotor core 1;

setting the number of pole slots in a rotor core 1 of the motor according to needs, and calculating according to motors with different numbers of pole slots so as to obtain the insertion angle of the permanent magnet monomer in the rotor core 1, the outer edge included angle of the permanent magnet monomer and the included angle of the width of the magnetic bridge;

inserting a rare earth permanent magnet monomer or a ferrite permanent magnet monomer into the magnetic steel groove 3; rare earth permanent magnet monomers or ferrite permanent magnet monomers with the same polarity are inserted into the same group of the magnetic steel grooves 3, and rare earth permanent magnet monomers or ferrite permanent magnet monomers with opposite polarities are inserted into the adjacent group of the magnetic steel grooves 3, so that the composite rotor of the permanent magnet motor of the electric vehicle is manufactured.

The electric vehicle permanent magnet motor composite rotor and the preparation method thereof provided by the embodiment have the design key points that:

(1) according to the embodiment, the structure and the preparation method of the motor are synchronously improved, so that the use amount of rare earth materials can be greatly reduced, the performance of the motor is improved, and the purposes of cost reduction and efficiency improvement are achieved. According to the composite rotor structure provided by the invention, through improvement of design, compared with a traditional permanent magnet rotor in a motor surface-mounted form of an electric vehicle, the adopted rare earth permanent magnet material is reduced by more than half, the material cost is greatly reduced, the environmental pollution caused by mining rare earth ores can be effectively reduced, in addition, the motor has high torque density and power density and strong irreversible demagnetization resistance, and the requirements of high-efficiency driving and speed regulation control of a new-energy electric vehicle can be met.

(2) According to the composite rotor of the permanent magnet motor of the electric vehicle and the preparation method thereof, the back electromotive force modification radius of the rotor core structure is set to be 66.16mm, and in the running process of the motor, the rotor core structure modifies the stator teeth to enable the back electromotive force of the motor to be sine-wave voltage, so that the torque pulsation and the motor noise output by the motor can be effectively reduced, and the output efficiency of the motor is improved.

According to the description of the above embodiments of the present invention, the obtained composite rotor of permanent magnet motor for electric vehicle with similar pole slots and other numbers and the preparation method thereof are all within the protection scope of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. The composite rotor of the permanent magnet motor of the electric vehicle is characterized by comprising a reluctance section rotor and a permanent magnet section rotor, and specifically comprises a hollow rotor core and a central rotating shaft, wherein a central rotating shaft hole for passing through the central rotating shaft is formed in the center of the rotor core and is tightly sleeved on the central rotating shaft of the motor; permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves, and permanent magnet monomers with opposite polarities are inserted into adjacent groups of magnetic steel grooves.

2. The electric vehicle permanent magnet motor composite rotor of claim 1, wherein the rotor core structure is further provided with a plurality of rotor weight reduction slots; the rotor lightening slots are arranged between the central rotating shaft and the magnetic steel slots, surround the center of a circle of the rotor iron core and are distributed in central symmetry.

3. The electric vehicle permanent magnet motor composite rotor of claim 1, wherein the back emf shaping radius of the rotor core is 66.16 mm; the number of poles of the rotor electrode is 8, the included angle between the direct axis of the rotor motor and the quadrature axis of the rotor motor is 22.5 degrees, and the back electromotive force modification center offset distance is 26.13 mm.

4. The composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 1, wherein the hollow rotor core is formed by laminating rotor sheets.

5. The composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 1, wherein the length of the magnetic steel slot is 9mm, the width of the permanent magnet monomer inserted into the magnetic steel slot is 2.5mm, and each permanent magnet monomer is symmetrically inserted into the magnetic steel slot at an angle of 20 degrees; the included angle of the outer edge of the permanent magnet monomer is 27.3 degrees, and the included angle width of the magnetic bridge is 35.44 degrees.

6. The composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 1, wherein the permanent magnet monomers are rare earth permanent magnet monomers or ferrite permanent magnet monomers.

7. A method for preparing the composite rotor of the permanent magnet motor of the electric vehicle according to any one of claims 1 to 6, which is characterized by comprising the following steps:

the method comprises the following steps that firstly, a rotor core of the composite rotor is prepared, the rotor core is of a hollow structure and comprises an outer wall and an inner wall, a central rotating shaft hole for passing through a central rotating shaft is formed in the center of the rotor core, and the rotor core is tightly sleeved on the central rotating shaft;

step two, arranging N groups of magnetic steel slots on the inner wall of the rotor core, wherein N is an even number, every two adjacent magnetic steel slots form a group of magnetic slot pairs, two magnetic steel slots in each group of magnetic slot pairs are arranged in a V shape, the opening direction of the magnetic steel slots faces the outer side of the rotor core, the magnetic slot pairs are distributed around the rotor core in a central symmetry manner, and the two magnetic steel slots in the same group of magnetic slot pairs are symmetrically arranged about a straight line passing through the center of the rotor core;

inserting a rare earth permanent magnet monomer or a ferrite permanent magnet monomer into the magnetic steel groove; rare earth permanent magnet monomers or ferrite permanent magnet monomers with the same polarity are inserted into the same group of magnetic steel grooves, and rare earth permanent magnet monomers or ferrite permanent magnet monomers with opposite polarities are inserted into the adjacent group of magnetic steel grooves.

8. The method for preparing the composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 7, wherein the first step further comprises the following steps:

step one, setting the back electromotive force modification radius of a rotor iron core structure to be 66.16 mm; when the motor runs, the rotor core structure shapes the stator teeth to enable the counter electromotive force of the motor to be sine wave voltage.

9. The method for preparing the composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 7, wherein the first step further comprises the following steps:

step two, arranging a plurality of rotor weight reduction grooves on the rotor core structure; the rotor lightening slots are arranged between the central rotating shaft and the magnetic steel slots and are distributed around the center of the rotor iron core in a central symmetry manner.

10. The method for preparing the composite rotor of the permanent magnet motor of the electric vehicle as claimed in claim 7, wherein the second step further comprises the following steps:

and step two, setting the number of pole slots in the rotor core of the motor, and calculating according to motors with different numbers of pole slots so as to obtain the insertion angle of the permanent magnet monomer in the rotor core, the outer edge included angle of the permanent magnet monomer and the included angle of the width of the magnetic bridge.

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