阅读说明：本技术 一种电动车驱动用低成本交替极永磁轮毂电机 (Low-cost alternating pole permanent magnet hub motor for driving electric vehicle ) 是由 周华伟 陶炜国 毛彦欣 张多 于 2019-09-23 设计创作，主要内容包括：本发明公开了一种电动车驱动用低成本交替极永磁轮毂电机,属于电机本体设计及制造领域。包括同轴外转子1和内定子2；所述外转子上的永磁体采用交替极结构,永磁体的充磁方向沿径向相同,即统一的沿径向指向或者背离圆心,永磁体之间的凸极铁心充当虚拟极,永磁体和虚拟极在外转子的内圆周上交替均匀分布,所述内定子2包含电枢齿5和齿靴6；本发明电机的电磁性能和常规N-S极阵列的永磁电机性能相当,并且永磁体的使用量大量减少,有效降低了电机成本。(The invention discloses a low-cost alternating pole permanent magnet hub motor for driving an electric vehicle, and belongs to the field of design and manufacture of motor bodies. Comprises a coaxial outer rotor 1 and an inner stator 2; the permanent magnets on the outer rotor are of an alternate pole structure, the magnetizing directions of the permanent magnets are the same along the radial direction, namely the permanent magnets point to or deviate from the circle center along the radial direction uniformly, the salient pole iron core between the permanent magnets serves as a virtual pole, the permanent magnets and the virtual pole are uniformly distributed on the inner circumference of the outer rotor alternately, and the inner stator 2 comprises armature teeth 5 and tooth shoes 6; the electromagnetic performance of the motor is equivalent to that of a permanent magnet motor of a conventional N-S pole array, the usage amount of permanent magnets is greatly reduced, and the cost of the motor is effectively reduced.)

1. A low-cost alternating-pole permanent magnet hub motor for driving an electric vehicle is characterized by comprising a coaxial outer rotor (1) and an inner stator (2); the permanent magnets on the outer rotor adopt an alternate pole structure, the magnetizing directions of the permanent magnets are the same along the radial direction, namely the permanent magnets point to or depart from the circle center along the radial direction uniformly, a salient pole iron core between two adjacent permanent magnets serves as a virtual pole, and the permanent magnets and the virtual pole are alternately and uniformly distributed on the inner circumference of the outer rotor;

the inner stator (2) comprises armature teeth (5) and tooth shoes (6); the permanent magnet, the virtual pole and the tooth shoe (6) have three combination modes:

wherein H₁Maximum thickness of bread-type permanent magnet, h₁Is the ridge length H of two sides of a bread-type permanent magnet₂Is the maximum thickness, h, of the bread-type virtual pole₂Is the ridge length, R, of two sides of a bread-type virtual pole₁，R₂Radius of the arc cut for the bread-type permanent magnet and the bread-type virtual pole, respectively,/₁，l₂Respectively, the radian spanned by the permanent magnet and the virtual pole along the circumference, L₁Thickness of the end of the tooth shoe, L₂Original thickness of the end of the tooth-boot, R_s1To cut the radius of a circular arc, R_s2The outer radius of the inner stator;

the first one is to adopt a bread type permanent magnet (31) and a bread type virtual pole (41); the bread-type permanent magnet and the bread-type virtual pole are protruded at the air gap side, and the end parts of the tooth shoes (6) are uniformly distributed on the same space circumference; the bread-type permanent magnet and the bread-type virtual pole satisfy the following relation: t is more than or equal to 0.5₁＝h₁/H₁≤1，0≤t₂＝h₂/H₂≤1，R₁≥R₂，H₁≥H₂，t₁And t₂Are independent of each other; the bread-type permanent magnet spans radian l along the circumference₁Arc l spanned by the bread-type virtual pole along the circumference₂Satisfy the relationship of₁>l₂And the minimum air gap thickness between the bread-type permanent magnet and the bread-type virtual pole from the stator is ensured to be equal;

the second one is to adopt tile-shaped permanent magnet (32) and tile-shaped virtual pole (42), the thicknesses of the tile-shaped permanent magnet and the tile-shaped virtual pole are equal, and l₁>l₂(ii) a The tooth shoe (6) is cut into a salient pole shape, L₁、L₂、R_s1、R_s2The relationship between them is: 0<L₁/L₂≤2.5，R_s1<R_s2；

The third one is to use tile-shaped permanent magnets (32) and tile-shaped virtual poles (42), and₁>l₂the thickness of tile-shaped permanent magnet is equal to that of tile-shaped virtual pole, and the tooth shoe(6) The end parts of the air gap are not cut and are uniformly distributed on the same circumferential space, and the air gap thickness is uniformly distributed on the circumferential space.

2. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: when t is₁＝t₂When the number is 1, the permanent magnet and the virtual pole are both tile-shaped.

3. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: when H is present₁>H₂And in order to ensure that the minimum air gap thickness between the bread-type permanent magnet and the bread-type virtual pole from the stator is equal, the bread-type permanent magnet higher than the bread-type virtual pole is embedded into the rotor yoke.

4. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: when the bread-type permanent magnet is adopted, a whole permanent magnet is obtained by cutting, or a plurality of blocky trapezoidal permanent magnets (311) are spliced to form the bread-type permanent magnet.

5. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: when the tile-shaped permanent magnet structure is adopted, the tile-shaped permanent magnet structure is formed by splicing a plurality of block-shaped rectangular permanent magnets (331).

6.A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: the polar arc coefficient range of the permanent magnet is set to be 0.5-0.7.

7. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: the stator slot width range is set to 2mm to 4 mm.

8. A low cost alternating pole permanent magnet hub motor for driving an electric vehicle as claimed in claim 1, wherein a minimum air gap range between the inner stator and the outer rotor is set to 0.3mm to 1 mm.

9. A low cost alternating pole permanent magnet in-wheel motor for driving electric vehicles as claimed in claim 1, wherein: the slot pole of the unit motor of the motor is matched to satisfy the formula Z₀＝2P₀+/-2 wherein Z₀And P₀The number of slots and the number of pole pairs of the unit motor are respectively.

Technical Field

The invention belongs to the field of motor design, and particularly relates to an alternating pole permanent magnet rotating motor for driving a wheel hub of an electric vehicle.

Background

Due to the depletion of traditional fossil energy and the deterioration of the environment, diesel locomotives that consume fossil energy are being replaced by new electric drive tools. The direct drive motor has the advantages of high reliability, small vibration noise and the like, and is widely applied to the fields of industrial equipment and vehicles. However, the direct drive motor has a large weight and volume due to the requirement of high torque density, so that the popularization and application of the direct drive motor are restricted. In recent years, permanent magnet motors have attracted more and more attention due to their excellent torque density and high efficiency. However, the permanent magnet is expensive, which limits the further popularization and application of the permanent magnet motor. In order to achieve riding comfort of the electric vehicle, torque ripple of the motor is strictly limited. Therefore, the cost of the permanent magnet motor is reduced, the torque pulsation of the motor is reduced, and the permanent magnet motor has very important significance for popularizing the permanent magnet motor for driving the electric vehicle and improving the competitiveness of the permanent magnet motor.

The documents IEEE Transactions on magnetics,52(7), July,2016.art.id 8104804, (Design and Analysis of Low-Cost Tubular Fault-Tolerant interface-Magnet Motor) propose a method using mixed excitation materials to reduce the Cost of the Motor, i.e. to replace half of the Permanent magnets with ferrite. However, this method greatly reduces the output performance of the motor due to the reduced excitation performance of the entire motor excitation material. The above method has certain limitations. Therefore, how to maintain the performance of the motor and greatly reduce the use amount of the permanent magnet has important significance. The patent 'a double modulation alternating pole permanent magnet vernier motor and application' of the patent with the patent application number of 201811288504.2 in China proposes a linear motor adopting an alternating pole permanent magnet array structure aiming at reducing the motor cost. Compared with the traditional surface-mounted permanent magnet motor, the using amount of the permanent magnet is greatly reduced, so that the cost of the motor is reduced.

Disclosure of Invention

The invention aims to solve the problems that the rare earth permanent magnet material of the permanent magnet motor for driving the wheel hub of the existing electric vehicle (such as an electric bicycle, an electric automobile and an electric tractor) is large in using amount and high in cost, the sine degree of counter potential is improved, torque pulsation is reduced, and operation stability is improved, and provides an outer rotor permanent magnet wheel hub motor based on an alternating pole structure.

The technical scheme adopted by the invention is as follows: a low-cost alternating pole permanent magnet hub motor for driving an electric vehicle comprises a coaxial outer rotor 1 and an inner stator 2; the permanent magnets on the outer rotor adopt an alternate pole structure, the magnetizing directions of the permanent magnets are the same along the radial direction, namely the permanent magnets point to or depart from the circle center along the radial direction uniformly, the salient pole iron cores between the permanent magnets serve as virtual poles, and the permanent magnets and the virtual poles are alternately and uniformly distributed on the inner circumference of the outer rotor;

the inner stator 2 comprises armature teeth 5 and tooth shoes 6; the permanent magnet, the virtual pole and the tooth shoe 6 have three combination modes:

the first is to use a bread-type permanent magnet 31 and a bread-type virtual pole 41; the bread-type permanent magnet and the bread-type virtual pole are protruded at the air gap side, and the end parts of the tooth shoes 6 are uniformly distributed on the same space circumference; the bread-type permanent magnet and the bread-type virtual pole satisfy the following relation: t is more than or equal to 0.5₁＝h₁/H₁≤1，0≤t₂＝h₂/H₂≤1，R₁≥R₂，H₁≥H₂，t₁And t₂Independently of one another, i.e. t₁May not be equal to t₂(ii) a The bread-type permanent magnet spans radian l along the circumference₁Arc l spanned by the bread-type virtual pole along the circumference₂Satisfy the relationship of₁>l₂And the minimum air gap thickness between the bread-type permanent magnet and the bread-type virtual pole from the stator is ensured to be equal;

the second one is to use tile-shaped permanent magnet 32 and tile-shaped virtual pole 42, the thicknesses of the tile-shaped permanent magnet and the tile-shaped virtual pole are equal, and l₁>l₂(ii) a The tooth shoe 6 is cut into a salient pole shape L₁、L₂、R_s1、R_s2The relationship between them is: 0<L₁/L₂≤2.5，R_s1<R_s2；

The third one is to use tile-shaped permanent magnets 32 and tile-shaped virtual poles 42, and₁>l₂the thickness of the tile-shaped permanent magnet is equal to that of the tile-shaped virtual pole, and the end of the tooth shoe 6The parts are not cut and are uniformly distributed on the same circumferential space, and the air gap thickness is uniformly distributed on the circumferential space;

wherein H₁Maximum thickness of bread-type permanent magnet, h₁Is the ridge length H of two sides of a bread-type permanent magnet₂Is the maximum thickness, h, of the bread-type virtual pole₂Is the ridge length, R, of two sides of a bread-type virtual pole₁，R₂Radius of the arc cut for the bread-type permanent magnet and the bread-type virtual pole, respectively,/₁，l₂Respectively the radian spanned by the permanent magnet and the virtual pole, L₁Thickness of the end of the tooth shoe, L₂Original thickness of the end of the tooth-boot, R_s1To cut the radius of a circular arc, R_s2Is the outer radius of the inner stator.

Further, when t is₁＝t₂When the number is 1, the permanent magnet and the virtual pole are both tile-shaped.

Further, when H is₁>H₂When the permanent magnet is used, the maximum thickness of the bread-type permanent magnet is larger than that of the bread-type virtual pole, and in order to ensure that the minimum air gap thickness between the bread-type permanent magnet 31 and the bread-type virtual pole 41 from the stator is equal, the bread-type permanent magnet 31 higher than the bread-type virtual pole 41 is embedded into the rotor yoke.

Further, when the bread-type permanent magnet 31 is used, a whole permanent magnet is cut or formed by splicing a plurality of block-shaped trapezoidal permanent magnets 311.

Further, when the tile-shaped permanent magnet 32 structure is adopted, a plurality of block-shaped rectangular permanent magnets 331 are spliced.

Further, the polar arc coefficient range of the permanent magnet is set to be 0.5-0.7.

Further, the stator slot width range is set to 2mm to 4 mm.

Further, a minimum air gap range between the inner stator and the outer rotor is set to 0.3mm to 1 mm.

Furthermore, the slot pole matching of the unit motor of the motor meets the formula Z₀＝2P₀+/-2 wherein Z₀And P₀The number of slots and the number of pole pairs of the unit motor are respectively.

The invention has the following beneficial effects:

1. the motor adopts an alternating pole structure, namely permanent magnets in the same excitation direction are adopted, compared with the permanent magnet of a conventional N-S array, the electromagnetic performance of the motor is equivalent to that of the permanent magnet of the conventional N-S array, the consumption of the permanent magnets is greatly reduced, and the cost of the motor is effectively reduced.

2. By adopting the bread-type permanent magnet and the bread-type virtual pole or cutting the tooth shoes, the sine degree of the air gap flux density can be improved, so that the sine degree of the no-load back electromotive force of the motor can be improved, and the torque pulsation of the motor is effectively reduced.

3. The outer rotor structure is adopted, the yoke part and the virtual pole of the outer rotor are made of Q235 steel, so that the heat dissipation of the permanent magnet is facilitated, the demagnetization risk of the permanent magnet caused by overhigh temperature is reduced, the cracking of a silicon steel sheet of a rotor core caused by the tension between the stator and the rotor in the installation process of the stator and the rotor is effectively eliminated, and the reliability of the motor is improved.

4. The Q235 steel is used for the outer rotor iron core to replace silicon steel sheets, so that the lamination process of punching sheets is reduced, the production process is simplified, and the cost is reduced.

5. The plurality of blocky permanent magnets are spliced to replace a whole permanent magnet, so that the processing difficulty of the permanent magnet and the manufacturing cost of the motor can be reduced, and the eddy current loss of the permanent magnet is reduced.

6. The motor adopts fractional slot concentrated winding, and the slot pole ratio satisfies the formula Z₀＝2P₀+/-2, a higher winding factor can be obtained, the harmonic component of the no-load counter electromotive force of the motor winding can be reduced, and the reliability of the motor is improved.

7. The fractional slot concentrated winding is adopted, so that the length of the winding edge end is reduced, the phase resistance of the motor is reduced, and the efficiency of the motor is improved.

8. The fractional slot concentrated winding, the bread-type permanent magnet blocking form, the bread-type virtual pole and the alternate pole structure not only reduce the eddy current loss and the copper loss, but also improve the operation efficiency of the motor; counter potential harmonics are restrained, and counter potential amplitude and output torque are improved; more importantly, the fault-tolerant operation capability of the motor is improved, the using amount of the permanent magnet is reduced, the cost of the motor is further reduced, and the reliability is improved.

Description of the drawings:

FIG. 1 is a block diagram of an exemplary motor I of the present invention;

FIG. 2 is an enlarged view of a portion of an exemplary motor I of the present invention;

FIG. 3 is a block diagram of an exemplary motor II of the present invention;

FIG. 4 is an enlarged fragmentary view of an exemplary motor II of the present invention;

FIG. 5 is a block diagram of an exemplary motor III of the present invention;

FIG. 6 is an enlarged fragmentary view of an exemplary motor III of the present invention;

FIG. 7 is a block diagram of an exemplary motor IV of the present invention;

FIG. 8 is an enlarged fragmentary view of an exemplary motor IV of the present invention;

fig. 9 is a structural view of a conventional motor;

fig. 10 is a partially enlarged view of a conventional motor;

FIG. 11 is a no-load back-emf waveform;

FIG. 12 is an electromagnetic torque waveform diagram;

in the figure: 1. an outer rotor; 2. an inner stator; 31. a bread-type permanent magnet; 311. a block-shaped trapezoidal permanent magnet; 32. a tile-shaped permanent magnet; 33. a rectangular permanent magnet; 331: a block-shaped rectangular permanent magnet; 41. a bread-type virtual pole; 42. tile-shaped virtual electrodes; 5. an armature tooth; 6.a tooth boot; 7. and (4) winding.

Detailed Description

The following describes in detail a specific embodiment of the present invention with reference to the accompanying drawings, and in order to more clearly and perfectly describe the structural features and advantageous effects of the motor of the present invention, a three-phase alternating-pole permanent magnet hub motor will be described in detail in a layered manner.

Fig. 1 is a structural view of an example motor i of the present invention, and fig. 2 is a partially enlarged view of the example motor i of the present invention, including an outer rotor 1 and an inner stator 2. The outer rotor 1 adopts a bread-shaped permanent magnet 31 and a bread-shaped virtual pole 41. The magnetizing directions of all the bread-type permanent magnets 31 are the same along the radial direction, namely, all the bread-type permanent magnets point to the center of a circle or deviate from the center of a circle.In the present example i, all the bread-type permanent magnets 31 are magnetized in directions radially away from the center of the circle. The rotor core 1 and the bread-type virtual pole 41 are integrally machined and cut by using a whole piece of Q235 steel. The bread type permanent magnet satisfies the following relationship: t is more than or equal to 0.5₁＝h₁/H₁Less than or equal to 1; the bread-type virtual pole 41 satisfies the relationship: t is not less than 0₂＝h₂/H₂≤1。t₁And t₂Independently of each other, t₁May not be equal to t₂；R₁≥R₂，H₁≥H₂When H is present₁>H₂When the permanent magnet is embedded into the rotor yoke, the minimum air gap length between the permanent magnet and the virtual pole from the stator is equal. In the example motor I of the invention, t₁＝t₂＝0.67，H₁＝2.78mm，H₂2.3 mm. Examples of the invention I₁＝7.3deg，l₂5.4deg, a little gap is left between the bread-type permanent magnet 31 and the bread-type virtual pole 41 to reduce the edge leakage. The inner stator 2 includes armature teeth 5 and tooth shoes 6, and ends of the tooth shoes 6 are uniformly distributed on a spatial circumference of an outer diameter of the stator. Fractional slot concentrated winding is used, and a winding 7 is wound on each armature tooth 5.

Fig. 3 is a structural view of an example motor ii of the present invention, and fig. 4 is a partially enlarged view of the example motor ii of the present invention. The structural parameters of the same structural parts of the example motor II and the example motor I are kept the same. In the example Motor II of the invention, t₁≠t₂And t is₁＝0.67，t₂＝0，H₁＝2.78mm，H₂＝2.3mm，l₁＝7.3deg，l₂5.4 deg. The bread-shaped permanent magnet 31 is formed by mutually splicing a plurality of block-shaped trapezoidal permanent magnets 311. The magnetization directions of the trapezoidal permanent magnets are kept the same in the radial direction, and in the motor II of the invention example, the trapezoidal permanent magnets deviate from the circle center in the radial direction.

Fig. 5 is a structural view of an example motor iii of the present invention, and fig. 6 is a partially enlarged view of the example motor iii of the present invention, including an outer rotor 1 and an inner stator 2. The outer rotor 1 comprises tile-shaped permanent magnets 32 and tile-shaped virtual poles 42, all of which have the same magnetization direction, in the present example, soThe permanent magnet with tiles 32 is magnetized in a direction radially away from the center of the circle. The rotor core and the tile-shaped virtual pole 42 are obtained by integrally machining and cutting a whole piece of Q235 steel. The entire tile-shaped permanent magnet 32 and the tile-shaped virtual pole 42 are the same thickness. The inner stator 2 includes armature teeth 5 and a tooth shoe 6, and an end of the tooth shoe 6 is cut, L₁And L₂The relationship between them is: 0<L₁/L₂Less than or equal to 2.5. In example III of the invention, L₁/L₂＝1。

Fig. 7 is a structural view of an example motor iv of the present invention, and fig. 8 is a partially enlarged view of the example motor iv of the present invention. The permanent magnet rotor comprises an outer rotor 1 and an inner stator 2, wherein the outer rotor 1 comprises a tile-shaped virtual pole 42 and a rectangular permanent magnet 33 formed by splicing two block-shaped rectangular permanent magnets 331. All the block-shaped rectangular permanent magnets have the same magnetizing direction, namely point to or deviate from the center of a circle along the radial direction. In the present example iv, the magnetizing directions of all the block-shaped rectangular permanent magnets 331 are radially away from the center of the circle, and the pole arc coefficient of the rectangular permanent magnet 33 is determined to be 0.58. The rotor core and the tile-shaped virtual pole 42 are integrally machined and cut by steel Q235. The inner stator 2 comprises armature teeth 5 and tooth shoes 6, and the ends of the tooth shoes 6 are uniformly distributed on the circumference of a space with the diameter as the outer diameter of the stator, namely the thickness of the whole air gap is uniform. In the motor iv of the example of the present invention, the width of the slot is set to 2.6mm to facilitate the winding of the coil. To avoid saturation of the armature teeth, the width of the armature teeth is optimized to be 6.4 mm. An air gap is reserved between the outer rotor 1 and the inner stator 2, and the thickness of the air gap of the motor is set to be 0.5 mm.

Fig. 9 is a structural view of a conventional motor, and fig. 10 is a partially enlarged view of the conventional motor. Comprising an outer rotor 1 and an inner stator 2. The outer rotor 1 comprises tile-shaped permanent magnets 32 with two polarities, and the magnetization directions of the tile-shaped permanent magnets 32 with the two polarities are respectively directed to the circle center along the radial direction and deviate from the circle center for magnetization. The permanent magnets are alternately and uniformly distributed on the circumference of the space, the thicknesses are equal, and the spanned radians are the same. The inner stator 2 includes armature teeth 5 and tooth shoes 6. All armature teeth 5 and tooth shoes 6 are identical in shape and are distributed uniformly over the spatial circumference. The air gap between the stator and the rotor is uniform in thickness. Fractional slot double layer concentrated winding is adopted. The parameters of the same structure in the motor of the inventive example remain unchanged.

Fig. 11 is a no-load back-emf waveform diagram, and fig. 12 is an electromagnetic torque waveform diagram. The no-load back-emf amplitude and the electromagnetic torque of examples i, ii, iii are slightly lower than those of the conventional motor and example iv due to the increase in the equivalent air gap thickness and the reduction in the amount of permanent magnets. However, because the sine degree of the air gap is improved by the examples I, II and III, the sine degree of the no-load counter potential is greatly improved, and the electromagnetic torque ripple is also greatly reduced.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.