A yokeless axial flux distributed wheel hub drive system for an automobile

Abstract

The application relates to the technical field of wheel hub motors, in particular to a yoke-free axial flux distributed wheel hub driving system for automobiles, which comprises a driving motor, the driving motor comprises a stator assembly and a rotor assembly, the rotor assembly comprises a left rotor and a right rotor, the left rotor and the right rotor each comprise a rotor back iron and multiple magnetic poles, the magnetic poles comprise first main magnetic poles, intermediate magnetic poles and auxiliary magnetic poles, the first main magnetic poles and the intermediate magnetic poles are arranged from outside to inside along the radial direction, the intermediate magnetic poles comprise axially superposed second main magnetic poles and soft magnetic magnetic poles, the soft magnetic magnetic poles are connected to the rotor back iron, the two sides of the intermediate magnetic poles are respectively provided with the auxiliary magnetic poles, the first main magnetic poles and the auxiliary magnetic poles are arranged from outside to inside along the radial direction, and the magnetizing directions of the first main magnetic poles, the second main magnetic poles and the auxiliary magnetic poles are all axial. The structure makes the driving motor have the anti-convex pole characteristic, the characteristic can expand the current angle adjusting range in the weak magnetic speed regulation control, and thus the speed regulation range of the motor is improved.

Description

Technical Field

[0001] This invention relates to the field of hub motor technology, specifically a yokeless axial flux distributed hub drive system for automobiles. Background Technology

[0002] Axial flux permanent magnet motors are gaining increasing attention due to their compact structure, high efficiency, and high power density, and are particularly suitable for hub motor drives in new energy vehicles.

[0003] While traditional permanent magnet motors offer numerous advantages, the inherent characteristics of permanent magnet fields also limit their adjustment, resulting in a limited speed range. Vehicles driven by hub motors require permanent magnet motors with a wide speed range, but the motor's speed is constrained by the magnetic field adjustment capability and bus voltage. Furthermore, axial flux permanent magnet motors typically employ surface-mounted pole structures, leading to significant eddy current losses.

[0004] In the existing technology, the main measures that can be taken to increase the maximum speed of a permanent magnet motor include: first, reducing the permanent magnet flux linkage; second, increasing the limiting current value of the permanent magnet motor; third, increasing the limiting voltage value of the permanent magnet motor; and fourth, changing the motor design to give the permanent magnet motor anti-salient pole characteristics.

[0005] Reducing the permanent magnet flux linkage will decrease the electromagnetic torque and power of the permanent magnet motor; increasing the limiting voltage or current value of the permanent magnet motor will place higher demands on the controller, and the cost will increase accordingly. Therefore, changing the motor design to give the permanent magnet motor anti-salient pole characteristics is the preferred way to enable the permanent magnet motor to have a wider speed range.

[0006] The following motor designs are disclosed in the prior art:

[0007] Chinese patent application CN201910905805.3 discloses an axial magnetic field anti-salient pole permanent magnet synchronous motor. This patent proposes three types of single-rotor, dual-stator axial magnetic field anti-salient pole permanent magnet synchronous motors. The rotor structure of these three motors includes a base disk and pole units. The base disk has through holes or grooves for embedding the pole units. Each pole unit consists of a magnetic conductor and a permanent magnet, with the permanent magnet embedded in the magnetic conductor. Although the base disk, pole unit shape, or mounting method of the three types of single-rotor, dual-stator axial magnetic field anti-salient pole permanent magnet synchronous motors differs, this patent increases the d-axis inductance by making the axial thickness of the pole unit greater than the axial thickness of the base disk, thus achieving anti-salient pole characteristics and improving the motor's speed regulation range. However, because the permanent magnets in the pole units of these three motors are embedded in the magnetic conductor, gaps exist between the permanent magnets in the same pole unit, causing a dip in the air gap magnetic flux density at a single pole unit.

[0008] In addition, Chinese patent application CN201811157231.8 discloses a composite amorphous alloy axial flux motor. This invention features a DC excitation winding structure fitted onto the outer stator core teeth, which allows for adjustment of the air gap magnetic field by changing the excitation current. During the motor's field weakening and speed-up phase, the demagnetizing current on the armature winding causes the soft magnetic poles connected to the permanent magnet to generate a reverse magnetic field, further weakening the magnetic field and enabling a wider operating speed range. However, this patent has soft magnetic poles on both the upper and lower sides of the circumferentially mounted permanent magnet. These soft magnetic poles and the permanent magnet can be considered as being connected in parallel on the magnetic circuit. The soft magnetic poles occupy a significant amount of space, sacrificing a larger permanent magnet flux linkage compared to traditional surface-mounted axial flux motors. The magnetic field magnitude needs to be adjusted via the DC excitation winding on the outer stator core teeth, complicating the manufacturing process. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a yokeless axial flux distributed hub drive system for automobiles, which has a high speed range and optimized structure.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] A yokeless axial flux distributed hub drive system for automobiles includes a drive motor, which comprises a stator assembly and a rotor assembly. The stator assembly is fixedly connected to the motor housing. The rotor assembly includes a left rotor and a right rotor, which are located on opposite sides of the stator assembly and coaxially arranged. There is a gap between the left and right rotors and the stator assembly. The left and right rotors have the same structure, each including a rotor back iron and multiple magnetic poles disposed on the rotor back iron. The rotor back iron is made of silicon steel sheets wound together.

[0012] The magnetic poles include a first main magnetic pole, an intermediate magnetic pole, and an auxiliary magnetic pole. The first main magnetic pole and the intermediate magnetic pole are arranged radially from the outside to the inside. The first main magnetic pole is located on the outside. The intermediate magnetic pole includes a second main magnetic pole and a soft magnetic pole that are axially superimposed. The soft magnetic pole is connected to the rotor back iron. Auxiliary magnetic poles are respectively provided on both sides of the intermediate magnetic pole. The first main magnetic pole and the auxiliary magnetic pole are arranged radially from the outside to the inside. The magnetization direction of the first main magnetic pole, the second main magnetic pole, and the auxiliary magnetic pole is axial.

[0013] The above structure enables the drive motor of the present invention to have anti-salient pole characteristics, which allows the motor to expand the current angle adjustment range in field weakening speed control, thereby improving the speed range of the motor.

[0014] The magnetic poles of the left and right rotors located on opposite sides of the stator assembly exhibit opposite magnetic properties, and adjacent magnetic poles on the same rotor exhibit opposite magnetic properties.

[0015] The material of the first main magnetic pole is neodymium iron boron.

[0016] The material of the second main magnetic pole is neodymium iron boron.

[0017] The material of the soft magnetic poles is silicon steel.

[0018] The auxiliary magnetic pole is made of ferrite.

[0019] The stator assembly includes a segmented stator core, a stator frame, and coils, which are bonded together by injecting high-temperature resistant epoxy resin.

[0020] The number of segmented stator cores is twelve. Each segmented stator core includes a stator tooth body and a stator tooth shoe. The two ends of the stator tooth body are respectively connected to the stator tooth shoe, and the coil is wound on the stator tooth body of the segmented stator core.

[0021] The stator frame is made of aluminum alloy, and twelve stator frame wings are evenly distributed on the outer side of the stator frame. A fan-shaped space with the same shape as the segmented stator core is formed between two adjacent stator frame wings, which is used to support the segmented stator core and the coils wound on the segmented stator core.

[0022] The left and right rotors each have ten magnetic poles.

[0023] The beneficial effects achieved by this invention are:

[0024] The drive motor used in the drive system of this invention uses soft magnetic poles on the d-axis magnetic circuit. The magnetic permeability of the soft magnetic poles is much greater than that of neodymium iron boron and air, which makes the d-axis inductance of the motor greater than the q-axis inductance, i.e., Ld>Lq. This gives the motor anti-salient pole characteristics. This characteristic allows the motor to expand the current angle adjustment range in field weakening speed control, giving the motor a wider speed range.

[0025] In addition, the motor's magnetic poles adopt a radial combination form. The middle magnetic pole inside the magnetic poles uses a soft magnetic pole and a second main magnetic pole connected in series and superimposed. Auxiliary magnetic poles are set on both sides of them to improve the utilization rate of the magnetic poles and improve the magnetic flux density waveform of the inner magnetic poles.

[0026] Furthermore, the present invention adopts an installation method in which the inner magnetic poles and the outer magnetic poles are radially combined, and the segmentation of the magnetic poles reduces the eddy current loss of the permanent magnet. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a schematic diagram of the electromagnetic component of the drive motor of the present invention;

[0029] Figure 2 This is a schematic diagram of the left rotor structure of the drive motor of the present invention;

[0030] Figure 3 A schematic diagram of the stator assembly structure of the drive motor of the present invention;

[0031] Figure 4 This is a schematic diagram of the stator frame structure of the drive motor of the present invention;

[0032] Figure 5 This is a schematic diagram of the segmented stator core structure of the drive motor of the present invention.

[0033] In the diagram: 1. Stator assembly; 2. Rotor assembly; 11. Coil; 12. Stator frame; 13. Segmented stator core; 21. Left rotor; 22. Right rotor; 211. Rotor back iron; 212. Auxiliary magnetic pole; 213. First main magnetic pole; 214. Second main magnetic pole; 215. Soft magnetic pole. Detailed Implementation

[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] Example:

[0036] like Figure 1 As shown, an axial flux-distributed hub drive system for automobiles without a yoke includes a drive motor. The drive motor includes a stator assembly 1 and a rotor assembly 2. The stator assembly 1 is fixedly connected to the motor housing. The rotor assembly 2 includes a left rotor 21 and a right rotor 22. The left rotor 21 and the right rotor 22 are located on both sides of the stator assembly 1 and are coaxially arranged with the stator assembly 1. There is a gap between the left rotor 21 and the right rotor 22 and the stator assembly 1.

[0037] like Figure 2 As shown, the left rotor 21 and the right rotor 22 have the same structure, both including a rotor back iron 211 and multiple magnetic poles disposed on the rotor back iron 211. The rotor back iron 211 is made of silicon steel sheet and has ten magnetic poles.

[0038] The two magnetic poles corresponding to the left rotor 21 and right rotor 22 located on opposite sides of the stator assembly 1 exhibit opposite magnetism, and adjacent magnetic poles on the same rotor exhibit opposite magnetism.

[0039] The magnetic poles include a first main magnetic pole 213, an intermediate magnetic pole, and auxiliary magnetic poles 212. The first main magnetic pole 213 and the intermediate magnetic pole are arranged radially from the outside to the inside, with the first main magnetic pole 213 located on the outside, serving as the outer magnetic pole. The intermediate magnetic pole includes a second main magnetic pole 214 and a soft magnetic pole 215, which are axially connected in series. The soft magnetic pole 215 is connected to the rotor back iron 211. Auxiliary magnetic poles 212 are respectively arranged on both sides of the intermediate magnetic pole, with the first main magnetic pole 213 and the auxiliary magnetic poles 212 arranged radially from the outside to the inside. The intermediate magnetic pole and the two auxiliary magnetic poles 212 on both sides constitute the inner magnetic pole.

[0040] This invention employs a radial combination of magnetic poles. The first main magnetic pole 213 is the outer magnetic pole, and the second main magnetic pole 214, the soft magnetic pole 215, and the two auxiliary magnetic poles 212 constitute the inner magnetic pole. The magnetic circuits of the outer and inner magnetic poles can be considered as parallel. The second main magnetic pole 214 and the soft magnetic pole 215 are connected in series in the magnetic circuit. The soft magnetic pole 215 occupies less space and sacrifices less permanent magnet flux. At the same time, the magnetic flux density waveform of the inner magnetic pole is improved by setting the auxiliary magnetic pole 212 with less residual magnetism.

[0041] The first main magnetic pole 213 is made of neodymium iron boron, and its magnetization direction is axial.

[0042] The material of the second main magnetic pole 214 is neodymium iron boron, and its magnetization direction is axial.

[0043] The soft magnetic pole 215 is made of silicon steel or other soft magnetic materials.

[0044] The auxiliary magnetic pole 212 is made of ferrite and is used to improve the air gap magnetic density. It has less residual magnetism and its magnetization direction is axial.

[0045] like Figures 3-5 As shown, the stator assembly 1 includes a segmented stator core 13, a stator frame 12, and a coil 11. The segmented stator core 13, the stator frame 12, and the coil 11 are bonded together by injecting high-temperature resistant epoxy resin to form the stator assembly 1.

[0046] The number of segmented stator cores 13 is twelve. Each segmented stator core 13 includes a stator tooth body and a stator tooth shoe. The two ends of the stator tooth body are respectively connected to the stator tooth shoe. The coil 11 is wound around the stator tooth body of the segmented stator core 13.

[0047] The stator frame 12 is made of aluminum alloy. Twelve stator frame wings are evenly distributed on the outer side of the stator frame 12. A fan-shaped space with the same shape as the segmented stator core 13 is formed between two adjacent stator frame wings. This space is used to support the segmented stator core 13 and the coil 11 wound on the segmented stator core 13.

Claims

1. A yokeless axial flux distributed hub drive system for automobiles, characterized in that, The device includes a drive motor, which comprises a stator assembly (1) and a rotor assembly (2). The stator assembly (1) is fixedly connected to the motor housing. The rotor assembly (2) includes a left rotor (21) and a right rotor (22). The left rotor (21) and the right rotor (22) are located on opposite sides of the stator assembly (1) and are coaxially arranged with the stator assembly (1). There is a gap between the left rotor (21) and the right rotor (22) and the stator assembly (1). The left rotor (21) and the right rotor (22) have the same structure, both including a rotor back iron (211) and multiple magnetic poles disposed on the rotor back iron (211). The pole includes a first main magnetic pole (213), an intermediate magnetic pole and an auxiliary magnetic pole (212). The first main magnetic pole (213) and the intermediate magnetic pole are arranged radially from the outside to the inside. The intermediate magnetic pole includes a second main magnetic pole (214) and a soft magnetic pole (215) that are axially superimposed. The soft magnetic pole (215) is connected to the rotor back iron (211). Auxiliary magnetic poles (212) are respectively provided on both sides of the intermediate magnetic pole. The first main magnetic pole (213) and the auxiliary magnetic pole (212) are arranged radially from the outside to the inside. The magnetization direction of the first main magnetic pole (213), the second main magnetic pole (214) and the auxiliary magnetic pole (212) is axial.

2. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The magnetic poles of the left rotor (21) and right rotor (22) located on opposite sides of the stator assembly (1) exhibit opposite magnetic properties, and the magnetic poles of adjacent magnetic poles on the same rotor exhibit opposite magnetic properties.

3. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The material of the first main magnetic pole (213) is neodymium iron boron.

4. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The material of the second main magnetic pole (214) is neodymium iron boron.

5. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The soft magnetic pole (215) is made of silicon steel.

6. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The auxiliary magnetic pole (212) is made of ferrite.

7. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The stator assembly (1) includes a segmented stator core (13), a stator frame (12), and a coil (11). The segmented stator core (13), stator frame (12), and coil (11) are bonded together by injecting epoxy resin to form the stator assembly (1).

8. The yokeless axial flux distributed hub drive system for automobiles according to claim 7, characterized in that, The number of segmented stator cores (13) is twelve. Each segmented stator core (13) includes a stator tooth body and a stator tooth shoe. The two ends of the stator tooth body are connected to the stator tooth shoe respectively. The coil (11) is wound around the stator tooth body of the segmented stator core (13).

9. The yokeless axial flux distributed hub drive system for automobiles according to claim 8, characterized in that, The stator frame (12) is made of aluminum alloy. Twelve stator frame wings are evenly distributed on the outer side of the stator frame (12). A fan-shaped space with the same shape as the segmented stator core (13) is formed between two adjacent stator frame wings.

10. The yokeless axial flux distributed hub drive system for automobiles according to claim 1, characterized in that, The left rotor (21) and the right rotor (22) are each provided with ten magnetic poles.

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