CN113131700B

CN113131700B - High power density in-wheel motor structure

Info

Publication number: CN113131700B
Application number: CN202110383182.5A
Authority: CN
Inventors: 孙木楚
Original assignee: Taiwan Bell Technology Jiangsu Co ltd
Current assignee: Tailing Technology Co ltd
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2022-03-22
Anticipated expiration: 2041-04-09
Also published as: CN113131700A

Abstract

The invention discloses a high-power-density hub motor structure which comprises an outer rotor, a stator, an inner rotor and a hub, wherein the outer rotor, the stator, the inner rotor and the hub are coaxially arranged; a permanent magnet is embedded in each magnetic steel groove, and the periphery of the outer rotor iron core is fixed with the hub; the stator is respectively provided with inner stator teeth and outer stator teeth, and inner stator grooves and outer stator grooves are respectively arranged between the adjacent inner stator teeth and between the outer stator teeth; a set of concentrated winding is respectively arranged in the inner stator slot and the outer stator slot, and the two sets of concentrated windings are connected in series; the end of each inner stator tooth and the end of each outer stator tooth are provided with at least one small slot to form a plurality of inner modulation teeth and outer modulation teeth. By using the invention, the output torque and the power density of the motor can be improved under the condition of not changing the stacking length and the outer diameter of the hub.

Description

High power density in-wheel motor structure

Technical Field

The invention belongs to the technical field of hub motors, and particularly relates to a high-power-density hub motor structure.

Background

Along with the development of motor technology, there is higher requirement to the output capacity of wheel hub motor for the electric motor car, and the electric motor car needs the motor to provide bigger power when heavily loaded starts or climbing, and traditional external rotor wheel hub motor can only fold the output torque who increases the motor fast through increasing under the unchangeable condition of assurance wheel hub external diameter, nevertheless folds the growth of length and has increaseed wheel hub motor's axial dimension, has influenced the installation space of motor on the car.

The structure of the existing hub motor is hub, rotor, stator, support, spindle, because the air gap diameter between the stator and the rotor is larger, the corresponding stator inner diameter and support diameter are larger, there are many spaces that can be utilized in the motor, under the condition of not changing the volume of the existing hub motor, utilize the space in the motor, raise the efficiency and output torque of the motor, and then improve the working capacity of the motor is the purpose of the invention.

Chinese patent publication No. CN 110676998A discloses a dual-rotor motor structure, which includes a casing, an outer rotor disposed in the casing, a stator disposed in the outer rotor, and an inner rotor disposed in the stator, and adopts a dual-air-gap structure of "outer rotor-stator-inner rotor", so as to increase the effective air-gap area of the motor.

Chinese patent publication No. CN109245468A discloses a dual-rotor synchronous motor using a permanent-magnet auxiliary cage barrier rotor, which mainly includes a casing, an outer rotor, a stator, an inner rotor and a rotating shaft, wherein the main bodies of the inner and outer rotors both use a magnetic barrier type reluctance rotor laminated along the axial direction, and the permanent magnets are magnetized in different directions in blocks with sine changes in non-conducting width and magnetizing direction, and short-circuit cage bars with different widths, which are wide near an air gap and narrow near the rotating shaft.

However, the above-described conventional techniques have problems that the motor torque density and the power density are not high enough, and the vibration noise is large.

Disclosure of Invention

The invention provides a high-power-density hub motor structure which can improve the output torque and power density of a motor and improve the output capacity of the motor under the condition of not changing the stacking length and the outer diameter of a hub.

A high-power-density hub motor structure comprises an outer rotor, a stator, an inner rotor and a hub which are coaxially arranged, wherein the outer rotor and the inner rotor are connected through a fixed support; the large opening of the V-shaped magnetic steel groove faces to the circle center, and the linear magnetic steel groove is arranged at a position close to the inner periphery of the outer rotor iron core; each magnetic steel groove is an axial through groove, a permanent magnet is embedded in each magnetic steel groove, and air gaps exist between the two non-axial end parts of each permanent magnet and the magnetic steel grooves; the periphery of the outer rotor iron core is fixed with the hub;

the stator is respectively provided with inner stator teeth and outer stator teeth, and inner stator grooves and outer stator grooves are respectively arranged between the adjacent inner stator teeth and between the outer stator teeth; a set of concentrated winding is respectively arranged in the inner stator slot and the outer stator slot, and the two sets of concentrated windings are connected in series;

the end of each inner stator tooth and the end of each outer stator tooth are provided with at least one small slot to form a plurality of inner modulation teeth and outer modulation teeth.

According to the invention, the inner rotor is additionally arranged in the hub, and the modulation teeth are arranged on the inner ring and the outer ring of the stator, so that the output torque and the power density of the motor are improved, the internal space of the hub motor is fully utilized, and the output capacity of the motor is improved.

Preferably, the periphery of outer rotor core evenly is provided with a plurality of dovetail grooves, and is fixed with the forked tail piece cooperation that the wheel hub inboard set up through the dovetail, and the assembly is simple and easy, can not take place the aversion phenomenon.

Preferably, the inner rotor adopts a surface-mounted structure and comprises an inner rotor iron core and a surface-mounted permanent magnet arranged on the periphery of the inner rotor iron core. The surface-mounted permanent magnet structure fully utilizes the inner space of the hub motor and has simple process.

Preferably, the tooth width of the inner modulation teeth is the same as the small slot width between adjacent inner modulation teeth, and the tooth width of the outer modulation teeth is the same as the small slot width between adjacent outer modulation teeth. At this time, the output torque of the motor is maximized, and the saturation degree of the magnetic circuit can be reduced.

Further, the widths of the notches of the inner stator slot and the outer stator slot satisfy the following relations:

b4＝(0.3～0.6)×b1

where b4 denotes the slot width and b1 denotes the tooth width of the corresponding inner or outer modulation tooth.

Preferably, the bottom of the small slot is a trapezoidal slot, and the size of the trapezoidal slot satisfies the following requirements:

where a1 denotes the depth of the trapezoidal groove and a2 denotes the depth of the small slot as a whole.

The small slot which meets the size relation has the minimum torque pulsation of the motor, and the size relation of the small slot at the inner side and the outer side of the stator meets the requirements.

Preferably, the outer diameter of the outer rotor and the outer diameter of the inner rotor satisfy the following relationship:

D1＝(1.6～2.5)×D2

wherein D1 is the outer diameter of the outer rotor, and D2 is the outer diameter of the inner rotor.

The winding at the inner side of the stator and the inner rotor form an inner rotor motor through a middle air gap; the winding outside the stator and the outer rotor form an outer rotor motor through an intermediate air gap.

Preferably, the pole arc coefficient of the permanent magnet in the V-shaped magnetic steel groove is the same as that of the permanent magnet in the linear magnetic steel groove, and the radian theta 2 of the large opening ends of the two permanent magnets in the V-shaped magnetic steel groove is the same as the radian theta 1 corresponding to the permanent magnet in the linear magnetic steel groove.

Further, the polarity of the permanent magnet in the V-shaped magnetic steel slot is opposite to that of the permanent magnet in the adjacent linear magnetic steel slot, thereby forming a pair of magnetic poles.

The number of inner stator slots Q1 and the number of outer stator slots Q2 may be equal or unequal.

Preferably, the number of inner stator slots Q1 is equal to the number of outer stator slots Q2, and the inner stator and outer stator winding current directions in the same radial direction are opposite; the number of the inner modulation teeth and the outer modulation teeth is Q, Q is N multiplied by Q1, and Q is P1+ P2, wherein P1 is the pole pair number of the outer rotor or the inner rotor, P2 is the pole pair number formed by the outer winding of the stator or the inner winding of the stator, and N is a positive integer.

The number of the modulation teeth is integral multiple of the number of the stator slots, and the stator not only plays a role of providing a rotating magnetic field, but also plays a role of modulating the magnetic field by the teeth.

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

1. the motor comprises two rotors, winding slots are respectively formed in the inner ring and the outer ring of the stator, two sets of windings are arranged, modulation teeth are arranged on the inner ring and the outer ring of the stator, and the number of the modulation teeth is integral multiple of the number of the slots. Because the winding all adopts concentrated winding, concentrated winding tip height is low, and corresponding resistance is little, and the copper loss of motor can reduce to some extent, and two sets of windings adopt the mode of establishing ties to connect, consequently, inside and outside stator produces back electromotive force simultaneously, owing to have two air gaps, the air gap area increases, has promoted the torque of motor, has further increased the power density of motor.

2. The modulation teeth are designed on the inner ring and the outer ring of the stator, the stator not only plays a role in providing a rotating magnetic field, but also plays a role in modulating the magnetic field through the tooth part, so that the power and the torque of the motor are further improved, and the stator is suitable for high-power density occasions and high-torque occasions. Because the modulation teeth are directly arranged on the stator, the magnetic modulation block is omitted, so that the motor has a simpler and more compact structure and is more convenient and faster to process and manufacture; and the low order harmonics present in the air gap can act with the armature windings to provide torque to the motor.

3. The end part of one stator tooth is provided with a plurality of modulation teeth to form a new stator tooth with auxiliary teeth, and the split teeth form is adopted, so that the number of stator slots can be reduced, and the form of fractional slot concentrated winding can be adopted. Compared with a distributed winding, the fractional-slot concentrated winding has the advantages that the winding end is shorter, the stator copper consumption is less, and the fractional-slot concentrated winding is more suitable for being installed in the structure of the hub motor.

4. The modulation teeth are designed in a special structure, and the magnetic circuits of the outer rotor are designed in an asymmetric and uniform distribution manner, so that the sine of a magnetic density waveform is improved, the torque pulsation is reduced, the saturation degree of the magnetic circuits is reduced, and the maximum output torque of the motor is improved; the inner rotor adopts a surface-mounted structure, and the process is simple.

Drawings

FIG. 1 is a schematic diagram of a high power density in-wheel motor structure according to the present invention;

FIG. 2 is an enlarged view of outer rotor and stator outer modulation teeth in an embodiment of the present invention;

FIG. 3 is an enlarged view of the inner rotor and inner modulation teeth of the stator in an embodiment of the present invention.

In the figure: 1-hub, 2-outer rotor, 21-outer rotor iron core, 22-air gap, 3-V-shaped magnetic steel slot, 4-linear magnetic steel slot, 5-outer rotor air gap, 6-outer modulation tooth, 7-stator, 71-inner stator tooth, 72-outer stator tooth, 73-small slot, 8-outer stator slot, 9-inner stator slot, 10-inner modulation tooth, 11-inner rotor air gap, 12-surface permanent magnet, 13-inner rotor, 14-fixed bracket and 15-inner rotor iron core.

Detailed Description

The invention will be described in further detail below with reference to the drawings and examples, which are intended to facilitate the understanding of the invention without limiting it in any way.

As shown in figures 1-3, the high-power-density hub motor structure comprises an outer rotor 2, a stator 7, an inner rotor 13 and a hub 1 which are coaxially arranged, wherein the outer rotor 2 and the inner rotor 13 are connected through a fixing support 14, and the hub 1 is driven to rotate together.

The outer rotor 2 comprises an outer rotor iron core 21 and a plurality of V-shaped magnetic steel grooves 3 uniformly arranged on the outer rotor iron core 21 in the circumferential direction, and a linear magnetic steel groove 4 is arranged between every two adjacent V-shaped magnetic steel grooves 3; the large opening of the V-shaped magnetic steel groove 3 faces the circle center, and the in-line magnetic steel groove 4 is arranged at a position close to the inner periphery of the outer rotor iron core 21. Each magnetic steel groove is an axial through groove, a permanent magnet is embedded in each magnetic steel groove, an air gap 22 exists between two non-axial end parts of each permanent magnet and each magnetic steel groove, and a gap also exists at one end of a small opening between the two permanent magnets in the V-shaped magnetic steel groove 3. The outer periphery of outer rotor core 21 is fixed to hub 1.

The polarity of the permanent magnet in the V-shaped magnetic steel groove 3 is opposite to that of the permanent magnet in the adjacent linear magnetic steel groove 4, so that a pair of magnetic poles is formed.

The inner rotor 13 adopts a surface-mounted structure and comprises an inner rotor iron core 15 and a surface-mounted permanent magnet 12 arranged on the periphery of the inner rotor iron core, the inner space of the hub motor is fully utilized, and the process is simple.

The inner side and the outer side of the stator 7 are respectively provided with inner stator teeth 71 and outer stator teeth 72, and inner stator slots 9 and outer stator slots 8 are respectively arranged between the adjacent inner stator teeth 71 and between the outer stator teeth 72. And two sets of concentrated windings are respectively arranged in the inner stator slot 9 and the outer stator slot 8 and are connected in series to share one set of power supply. An outer rotor air gap 5 exists between the outer rotor 2 and the stator 7, and an inner rotor air gap 11 exists between the inner rotor 13 and the stator 7. An inner rotor motor is formed by an inner side winding of the stator 7 and an inner rotor 13 through an inner rotor air gap 11; the outer side winding of the stator and the outer rotor 2 form an outer rotor motor through an outer rotor air gap 5.

The number Q1 of inner stator slots 9 and the number Q2 of outer stator slots 8 may be equal or unequal. The two sets of windings are concentrated windings, the span, the number of parallel branches and the number of winding turns are the same, and the two sets of windings are connected in series, so that one power supply is used for supplying current to the two sets of windings. If Q1 is Q2, the inner stator and outer stator windings in the same radial direction have opposite current directions. The number of the modulation teeth is Q, and Q is N multiplied by Q1; and Q is P1+ P2, where P1 is the pole pair number of the outer (inner) rotor and P2 is the pole pair number formed by the outer (inner) stator winding. As shown in FIG. 1, the slot poles of the present embodiment are mated to 18 slots 56 poles.

In the present invention, the end of each of the inner 71 and outer 72 stator teeth is provided with one or more small slots forming a plurality of inner 10 and outer 6 modulation teeth.

As shown in fig. 2, for the outer modulation teeth 6, the width of the outer modulation teeth 6 should satisfy the relationship b 1-b 2-b 3, so that the output torque of the motor is maximized, the saturation degree of the magnetic circuit can be reduced, and the motor is suitable for high power density applications. Wherein b1 and b3 are the tooth widths of the outer modulation teeth respectively, and b2 is the width of the small slot 73 between the modulation teeth.

Meanwhile, the notch width b4 of the outer stator slot 8 satisfies the following relation: b4 is (0.3-0.6) x b 1. The bottom of the small open groove 73 is a trapezoidal groove, and the size of the trapezoidal groove meets the following relationship:

a1 denotes the depth of the trapezoidal groove and a2 denotes the depth of the small slot as a whole. At this time, the motor torque ripple is minimized.

As shown in fig. 3, the dimensional relationships for the inner modulation teeth 10 are all in accordance with the requirements described above.

The new structure design reduces the magnetic circuit saturation and further improves the motor torque and power density. The stator not only plays a role in providing a rotating magnetic field, but also has a tooth part playing a role in modulating the magnetic field and simultaneously achieving a role in outputting torque, so that the torque output capacity of the motor is improved, the structure is simple, and the manufacturing and processing difficulty is low.

As shown in fig. 2, the pole arc coefficients of the linear permanent magnet and the V-shaped permanent magnet must be equal to each other, and the relationship θ 1 — θ 2 must be satisfied.

Compared with the traditional permanent magnet synchronous hub motor and the magnetic gear motor. The invention adopts the inner rotor and the outer rotor, and the outer rotor is provided with the asymmetric V-shaped permanent magnet, the pole arc coefficients of the V-shaped permanent magnet and the straight permanent magnet are equal, the sine of a magnetic field is improved, the torque fluctuation is reduced, and the torque and the power density of the motor are improved.

Specifically, in this embodiment, an 11-inch hub motor is taken as an example, the hub 1 and the outer rotor 2 may be connected in a dovetail groove fit manner, the outer rotor 2 is provided with V-shaped magnetic steels and linear magnetic steels distributed at intervals along the circumference, and the adjacent V-shaped magnetic steels and linear magnetic steels have opposite polarities and are uniformly distributed with 28 pairs of polar magnetic steels. And a 0.35mm air gap is arranged between the outer rotor 2 and the stator. The outer diameter D1 of the outer rotor is 250mm, and the outer diameter D2 of the inner rotor is 120 mm. The polar arc coefficient of the V-shaped magnetic steel is equal to that of the linear magnetic steel, the polar arc coefficients are all 0.94, and the included angle theta 1 is equal to theta 2 and equal to 6 degrees. The inner circle and the outer circle of the stator 7 are respectively provided with 18 stator slots for embedding the inner stator coil and the outer stator coil, and the inner stator coil and the outer stator coil are connected in series and share one power supply; the windings take the form of concentrated windings. 36 modulation teeth are respectively arranged on the inner ring and the outer ring of the stator.

Wherein, the size of outer modulation tooth 6 is: b1 ═ b2 ═ b3 ═ 11.4 mm; b4 ═ 6 mm; the size of the trapezoid groove is as follows: a1 ═ 1.35 mm; a 2-4.05 mm. And a 0.35mm air gap is arranged between the stator and the inner rotor.

The invention adopts a double-air-gap structure of 'outer rotor-stator-inner rotor', which increases the effective air gap of the motor, thereby improving the torque density of the motor. The magnetic regulating ring is combined with the stator, and the inner ring and the outer ring of the stator are simultaneously provided with the regulating teeth, so that the internal space of the motor is utilized to the maximum extent, and the power density and the torque density are further improved. The whole motor is simple in structure, reduces machining difficulty, is easy to realize technically, and improves reliability. The number of the modulation teeth is integral multiple of the number of the stator slots, and the stator not only plays a role of providing a rotating magnetic field, but also plays a role of modulating the magnetic field by the teeth. Concentrated windings are respectively distributed on the inner ring and the outer ring of the stator, the concentrated windings are simple in process, high in efficiency, high in slot filling rate, short in end portion of the motor, small in resistance and low in copper consumption, and the power density of the motor is further improved.

The embodiments described above are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions and equivalents made within the scope of the principles of the present invention should be included in the scope of the present invention.

Claims

1. The utility model provides a high power density in-wheel motor structure, includes outer rotor (2), stator (7), inner rotor (13) and wheel hub (1) that arrange with the axle center, outer rotor (2) and inner rotor (13) between connect through fixed bolster (14), its characterized in that:

the outer rotor (2) comprises an outer rotor iron core (21) and a plurality of V-shaped magnetic steel grooves (3) which are uniformly arranged on the outer rotor iron core (21) in the circumferential direction, and a linear magnetic steel groove (4) is arranged between every two adjacent V-shaped magnetic steel grooves (3); the large opening of the V-shaped magnetic steel groove (3) faces to the circle center, and the linear magnetic steel groove (4) is arranged at a position close to the inner periphery of the outer rotor iron core (21); each magnetic steel groove is an axial through groove, a permanent magnet is embedded in each magnetic steel groove, and air gaps (22) are formed between the two non-axial end parts of each permanent magnet and the magnetic steel grooves; the periphery of the outer rotor iron core (21) is fixed with the hub (1);

the stator (7) is respectively provided with inner stator teeth (71) and outer stator teeth (72), and inner stator slots (9) and outer stator slots (8) are respectively arranged between the adjacent inner stator teeth (71) and between the adjacent outer stator teeth (72); a set of concentrated winding is respectively arranged in the inner stator slot (9) and the outer stator slot (8), and the two sets of concentrated windings are connected in series; the end parts of each inner stator tooth (71) and each outer stator tooth (72) are provided with at least one small slot to form a plurality of inner modulation teeth (10) and outer modulation teeth (6);

the tooth width of the inner modulation teeth (10) is the same as the small slot width between the adjacent inner modulation teeth (10), and the tooth width of the outer modulation teeth (6) is the same as the small slot width between the adjacent outer modulation teeth (6);

the widths of the notches of the inner stator groove (9) and the outer stator groove (8) both satisfy the following relation:

b4＝(0.3～0.6)×b1

2. The high-power-density in-wheel motor structure according to claim 1, characterized in that a plurality of dovetail grooves are uniformly formed in the outer periphery of the outer rotor core (21) and are matched and fixed with dovetail blocks arranged on the inner side of the wheel hub (1) through the dovetail grooves.

3. The high power density hub motor structure according to claim 1, wherein the inner rotor (13) is of a surface-mounted structure, and comprises an inner rotor core (15) and surface-mounted permanent magnets (12) arranged on the periphery of the inner rotor core (15).

4. The high power density in-wheel motor structure of claim 1, wherein the bottom of the small slot is a trapezoidal slot, and the size of the trapezoidal slot satisfies the following requirements:

5. The high power density in-wheel motor structure of claim 1, characterized in that the outer diameter of the outer rotor and the outer diameter of the inner rotor satisfy the following relationship:

D1＝(1.6～2.5)×D2

6. The high-power-density in-wheel motor structure according to claim 1, characterized in that the pole arc coefficients of the permanent magnets in the V-shaped magnetic steel slot (3) are the same as the pole arc coefficients of the permanent magnets in the in-line magnetic steel slot (4), and the radian theta 2 of the large opening ends of the two permanent magnets in the V-shaped magnetic steel slot (3) is the same as the radian theta 1 corresponding to the permanent magnets in the in-line magnetic steel slot (4).

7. The high power density in-wheel motor structure of claim 1, characterized in that the number of inner stator slots (9) Q1 is equal to the number of outer stator slots (8) Q2, the inner stator and outer stator winding current in the same radial direction are opposite; the number of the inner modulation teeth (10) and the number of the outer modulation teeth (6) are Q, Q is N multiplied by Q1, and Q is P1+ P2, wherein P1 is the pole pair number of the outer rotor or the inner rotor, P2 is the pole pair number formed by the outer winding of the stator or the inner winding of the stator, and N is a positive integer.

8. The high power density in-wheel motor structure of claim 1, characterized in that the number of inner stator slots (9) Q1 is not equal to the number of outer stator slots (8) Q2.