Magnetic flux controllable hub motor and design method thereof

Abstract

The invention belongs to the field of electric automobile motors, and particularly relates to a magnetic flux controllable hub motor and a design method thereof. According to the invention, a self-leakage magnetic circuit and an inter-pole leakage magnetic circuit are constructed on the rotor at the same time, and the leakage flux and effective flux of the motor are jointly adjusted through the change of armature current under different working conditions, so that the output torque can be improved and the speed regulation range can be widened; besides, through reasonable design of key parameters such as the interelectrode flux leakage magnetic circuit length and the self-flux leakage magnetic circuit length on the motor flux leakage magnetic circuit, the d-axis flux linkage under the low-speed working condition is improved, the d-axis flux linkage under the high-speed working condition is reduced, and finally the magnetic flux controllability under the full working condition is enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electric vehicle motors, and particularly relates to a magnetic flux controllable wheel hub motor and a design method thereof. BACKGROUND

[0002] In order to promote green development and alleviate the problems such as energy crisis and environmental pollution caused by the development of traditional fuel vehicles, the automobile industry is transforming towards electrification, networking and intelligentization, which has become the mainstream trend of the automobile industry. Among them, electric vehicles, especially pure electric vehicles, are booming worldwide due to their advantages such as energy saving and emission reduction, simple structure, and high driving comfort. Electric vehicles usually have multiple operating conditions such as frequent acceleration / deceleration, climbing and high-speed cruising, which puts forward more stringent requirements on the power density, speed range and efficiency of the core power component, i.e., the driving motor of the electric vehicle.

[0003] A hybrid excitation concept is proposed in the document with Chinese patent number CN202110326447.8, which adds a set of electric excitation windings to the traditional permanent magnet motor. By adjusting the size and direction of the electric excitation winding current, the total magnetic flux of the excitation source is changed, thereby controlling the total magnetic flux of the motor, so it can also be called a variable excitation source permanent magnet motor. However, excessive electrical density and the resulting additional heat pose more stringent requirements on the cooling system of this type of motor, and the additional copper loss inevitably leads to a decrease in efficiency.

[0004] In order to solve the above problems, the document with Chinese patent number CN202010090457.1 proposes a "memory" motor concept, which introduces permanent magnet materials with the ability to change the magnetization state online (such as aluminum-nickel-cobalt) and magnetization windings into the permanent magnet motor. By applying a short-time demagnetization (or magnetization) current, the magnetization strength of the permanent magnet material of the motor can be adjusted online, the magnetic flux of the permanent magnet source is changed, and the flexible adjustment and control of the total magnetic field of the motor are realized, so it can also be called a variable permanent magnet source permanent magnet motor. However, in this type of variable permanent magnet source permanent magnet motor, in order to effectively adjust the air gap magnetic flux under different operating conditions, a set of magnetization windings and corresponding control circuits need to be added, which objectively increases the complexity of the structure of the motor system, and to some extent, reduces the power density and reliability of the motor.

[0005] It can be seen that the balance of the vehicle permanent magnet motor in terms of wide speed range, efficiency in high speed area, and magnetic field control still has problems, and it is difficult to fully meet the diverse performance requirements of the variable operating conditions of the vehicle driving motor. SUMMARY

[0006] In view of the above problems, the purpose of the present application is to provide a magnetic flux controllable wheel hub motor to meet the diverse performance requirements of the variable operating conditions of the vehicle driving motor, and to provide a design method for enhancing the magnetic flux controllable ability of the vehicle permanent magnet motor.

[0007] To achieve the above object, the present application provides the following technical solutions.

[0008] In a first aspect, the present application provides a flux-controllable wheel hub motor, comprising:

[0009] a stator;

[0010] a rotor coaxially arranged outside the stator;

[0011] m pieces of trapezoidal magnetic barriers, m groups of double-layer arc-shaped permanent magnets and m groups of double-layer arc-shaped magnetic barriers are alternately arranged in the circumference of the inside of the rotor, m being an integer greater than 3;

[0012] the center of the trapezoidal magnetic barrier is located on the d-axis, and each trapezoidal magnetic barrier does not contact the outer edge of the rotor;

[0013] the double-layer arc-shaped magnetic barrier comprises two layers of arc-shaped magnetic barriers with the same structure, and the center of the arc-shaped magnetic barrier is located on the q-axis;

[0014] the double-layer arc-shaped permanent magnet comprises two layers of arc-shaped permanent magnets with the same structure, one end of the arc-shaped permanent magnet contacts the end of the corresponding arc-shaped magnetic barrier, and the other end does not contact the end of the corresponding trapezoidal magnetic barrier;

[0015] the arc-shaped permanent magnet is magnetized in the radial direction, the arc-shaped permanent magnets on the same pole are magnetized in the same direction, and the arc-shaped permanent magnets on adjacent poles are magnetized in opposite directions.

[0016] Further, the main magnetic circuit path of the flux-controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-adjacent pole S pole of the outer arc-shaped permanent magnet-adjacent pole N pole of the inner arc-shaped permanent magnet-air gap-stator tooth-stator yoke-stator tooth-air gap-inner side of the rotor-S pole of the permanent magnet.

[0017] Further, the self-leakage magnetic circuit path of the flux-controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-self-leakage magnetic bridge-S pole of the inner arc-shaped permanent magnet.

[0018] Further, the inter-pole leakage magnetic circuit path of the flux-controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-adjacent pole S pole of the outer arc-shaped permanent magnet-adjacent pole N pole of the inner arc-shaped permanent magnet-inner side of the rotor-S pole of the inner arc-shaped permanent magnet.

[0019] Further, m=10.

[0020] Further, the radial widths of the arc-shaped magnetic barriers are the same. The radial width specifically refers to the width in the thickness direction.

[0021] Furthermore, the long side B of the trapezoidal magnetic barrier a With short side B b The structural relationship is 1.5 ≤ (B a / B b ≤2.5.

[0022] Furthermore, the low-speed operation of the flux-controlled hub motor accounts for 40% of the total operating conditions (m1), and the high-speed operation accounts for 60% of the total operating conditions (m2). The long side B of the trapezoidal magnetic barrier... a =22mm, the short side B of the trapezoidal magnetic barrier b =18.2mm, circumferential length L of the arc-shaped permanent magnet pm =25.1mm, radial width H pm =4mm, circumferential length ω between the poles of the arc-shaped permanent magnet rib =35mm, air gap length g=1mm, arc length ω corresponding to a pair of poles g =91mm, proportionality coefficient k is 34, proportionality coefficient t is 15, and the radial distance C from the outer edge of the trapezoidal magnetic barrier to the outer edge of the rotor is... d The radial distance C between the outer edge of the trapezoidal magnetic barrier and the outer arc-shaped permanent magnet b The sum is 8mm.

[0023] Furthermore, C d =5mm, C b =3mm.

[0024] Secondly, the present invention provides a design method for the above-mentioned flux-controlled hub motor, wherein the design method comprises: determining the radial distance C between the outer edge of the trapezoidal magnetic barrier and the outer edge of the rotor according to the following formula. d The radial distance C between the outer edge of the trapezoidal magnetic barrier (8) and the outer arc-shaped permanent magnet. b sum:

[0025]

[0026] Where g is the air gap length, ω g It is the arc length corresponding to a pair of poles, μ0 is the free permeability, and ω rib t is the circumferential length between the poles of the arc-shaped permanent magnet, m1 is the proportion of the low-speed condition to the total condition, m2 is the proportion of the high-speed condition to the total condition, and k and t are preset proportionality coefficients.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention proposes a flux-controllable hub motor structure, which simultaneously constructs a "self-leakage magnetic circuit" and an "inter-pole leakage magnetic circuit". By changing the armature current under different operating conditions, the leakage magnetic flux and effective magnetic flux of the motor can be adjusted together, which helps to improve the output torque and widen the speed range.

[0029] 2. This invention proposes a design method to enhance the controllability of magnetic flux. By rationally designing key parameters such as the inter-pole leakage flux path length and the self-leakage flux path length on the motor leakage flux path, the d-axis flux linkage ψ under low-speed conditions can be simultaneously improved. d+ Reduce d-axis flux linkage ψ under high-speed conditions d- And ultimately achieve enhanced magnetic flux controllability under all operating conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 A topology diagram of a flux-controlled hub motor according to an embodiment of the present invention is shown;

[0032] Figure 2 Partially shown Figure 1 The magnetization direction and magnetic circuit of the arc-shaped permanent magnet of the flux-controllable hub motor shown in the figure.

[0033] Figure 3 It shows Figure 1 A simplified magnetic circuit diagram of a flux-controlled hub motor with the structure shown.

[0034] Figure 4 It shows Figure 1 Partial view and key parameters of the flux-controlled hub motor shown in the figure;

[0035] Figure 5 It shows Figure 1 The flux controllability curves of the flux-controlled hub motor with the structure shown are displayed under low-speed (A) and high-speed (B) conditions.

[0036] Figure 6 It shows Figure 1 The torque and power envelopes of the flux-controlled hub motor with the structure shown are displayed under all operating conditions. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] An embodiment of the first aspect of the present invention provides a flux-controllable hub motor, the structure of which is described below. Figure 1 This is a topology diagram of a flux-controlled hub motor. It can be clearly seen that the stator 2 and end cover are fixedly connected together and mounted on the frame. The rotor 1 is coaxially located outside the stator 2, with an air gap between the rotor 1 and stator 2. The center of the rotor 1 is used to house the shaft. Inside the rotor 1, 10 trapezoidal magnetic barriers 8, 10 sets of double-layered arc-shaped permanent magnets 6, and 10 sets of double-layered arc-shaped magnetic barriers 5 are arranged alternately along the circumference. The center of the trapezoidal magnetic barrier 8 is located on the d-axis, and the trapezoidal magnetic barrier 8 does not contact the outer edge of the rotor 1. The double-layered arc-shaped magnetic barrier 5 consists of two layers of arc-shaped magnetic barriers with identical structures and their centers located on the q-axis. The double-layered arc-shaped permanent magnet 6 consists of two layers of arc-shaped permanent magnets with identical structures. One end of each arc-shaped permanent magnet is in contact with the end of its corresponding arc-shaped magnetic barrier, while the other end is not in contact with the end of its corresponding trapezoidal magnetic barrier 8, forming a radial self-leaking magnetic bridge. The hypotenuse of the trapezoidal magnetic barrier 8 should be parallel to the radial sides of each layer of arc-shaped permanent magnets. Therefore, preferably, the long side B of the trapezoidal magnetic barrier... a With short side B b The structural relationship is 1.5 ≤ (B a / B b ≤2.5. The inner layer of arc-shaped permanent magnets is closer to stator 2, and the outer layer of arc-shaped permanent magnets is farther away from stator 2. The part between the outer layer of arc-shaped permanent magnets and the outer edge of rotor 1 is called the outer side of rotor, and the part between the inner layer of arc-shaped permanent magnets and the inner edge of rotor 1 is called the inner side of rotor.

[0039] Figure 2 Partially shown Figure 1 The magnetization direction and magnetic circuit of the permanent magnets in the flux-controlled hub motor shown are illustrated. To construct a self-leaking magnetic circuit and an inter-pole leakage magnetic circuit for coordinated leakage flux, the arc-shaped magnetic barrier (5) and the trapezoidal magnetic barrier (8) do not contact each other, and the trapezoidal magnetic barrier (8) does not contact the outer edge of the rotor; the arc-shaped permanent magnets are all magnetized radially, that is, along the thickness direction. The magnetization direction of each arc-shaped permanent magnet on the same pole is the same, and the magnetization direction of the arc-shaped permanent magnets on adjacent poles (both sides of the q-axis) is opposite.

[0040] Main magnetic circuit path: S pole of inner arc permanent magnet - N pole of outer arc permanent magnet - outside of rotor - S pole of adjacent outer arc permanent magnet - N pole of adjacent inner arc permanent magnet - air gap - stator teeth - stator yoke - stator teeth - air gap - inside of rotor - S pole of permanent magnet, forming a closed loop;

[0041] Self-leaking magnetic circuit: S pole of inner arc-shaped permanent magnet - N pole of outer arc-shaped permanent magnet - outside of rotor - self-leaking magnetic bridge - S pole of inner arc-shaped permanent magnet, forming a closed loop;

[0042] Inter-pole leakage magnetic circuit: S pole of inner arc permanent magnet - N pole of outer arc permanent magnet - outside of rotor - S pole of adjacent outer permanent magnet - N pole of adjacent inner arc permanent magnet - inside of rotor - S pole of inner arc permanent magnet, forming a closed loop;

[0043] The flux-controlled hub motor provided by this invention automatically adjusts the ratio of main magnetic flux to leakage flux according to load and speed, meeting the diverse performance requirements of automotive drive motors under varying operating conditions. Under low-speed, heavy-load conditions, the large armature current causes the self-leakage magnetic circuit and inter-pole leakage magnetic circuit to approach deep saturation, nearly closing the leakage flux path. This significantly reduces the inter-pole leakage flux and self-leakage flux of the permanent magnet, leaving only the main magnetic circuit present. This increases the effective main magnetic flux and improves the motor's output torque. Under high-speed, light-load conditions, the induced electromotive force increases, and the armature current decreases, reducing the saturation of the leakage magnetic circuit. The main magnetic circuit, self-leakage magnetic circuit, and inter-pole leakage magnetic circuit all exist, increasing the inter-pole leakage flux and self-leakage flux of the permanent magnet. This achieves "self-weakening of the permanent magnet" in the high-speed range, meaning that without applying a large direct-axis demagnetizing current, the main magnetic flux entering the air gap can be automatically weakened, thereby suppressing the rise of back electromotive force, reducing the weakening current component and the corresponding weakening copper loss, and improving operating efficiency in the high-speed range.

[0044] To improve torque and broaden the speed range, this invention further investigates the flux controllability of the flux-controllable hub motor under low-speed conditions.

[0045] This invention defines flux controllability M to reflect the degree of change in effective flux; to clearly describe the change in flux under different operating conditions, flux controllability M under low-speed operating conditions is defined. l and flux controllability under high-speed operating conditions M h .

[0046] Flux controllability M under low-speed heavy-load conditions l It refers to the degree of magnetic flux adjustment under low-speed heavy-load conditions relative to the no-load conditions. It can be defined as the ratio between the difference between the d-axis flux linkage under low-speed conditions and the d-axis flux linkage under no-load conditions and the d-axis flux linkage under no-load conditions.

[0047] Flux controllability M under high-speed and light-load conditions hIt refers to the degree of flux adjustment under high-speed light-load conditions relative to the no-load conditions. It can be defined as the ratio between the difference between the d-axis flux linkage under high-speed conditions and the d-axis flux linkage under no-load conditions and the d-axis flux linkage under no-load conditions.

[0048] (1)

[0049] In the formula, M l For the controllability of magnetic flux under low-speed conditions, M h For the controllability of magnetic flux under high-speed operating conditions, ψ d+ For low-speed operation, ψ is the d-axis flux linkage. d0 For the d-axis flux linkage under no-load conditions, ψ d- For high-speed operation, the d-axis flux linkage.

[0050] From formula (1):

[0051] (2)

[0052] Based on the relationship between magnetic flux and salient pole ratio and formula (2), the d-axis flux linkage under different operating conditions is expressed as follows:

[0053] (3)

[0054] In the formula, ψ ξ For effective magnetic flux, ψ pm For permanent magnet flux linkage, N is the number of turns in the armature winding, and R is... eq K is the q-axis equivalent reluctance. ξ It is the salient pole ratio; This is the q-axis current;

[0055] From formula (3), we can see that the saliency ratio K ξ It is an important parameter affecting the controllability of magnetic flux.

[0056] salient pole ratio K ξ Closely related to the reluctance of the motor, in order to analyze the salient pole ratio K ξ The relationship between the magnetic reluctance of the motor and the present invention Figure 3 It shows Figure 1 A simplified magnetic circuit diagram of a flux-controlled hub motor with the structure shown.

[0057] according to Figure 3 Simplified magnetic circuit diagram of a flux-controlled hub motor, salient pole ratio K ξ The relationship with the magnetic reluctance in the magnetic circuit is as follows:

[0058] (4)

[0059] In the formula, K ξ L is the salient pole ratio. q For the q-axis inductance, L dR is the d-axis inductance. pmc For R pm and R c2 The equivalent reluctance of these two reluctances, 1 / R pmc =1 / R pm +1 / R c2 R pm For permanent magnet reluctance, R c2 For self-leaking magnetic reluctance, R c1 R is the inter-electrode leakage reluctance. c (i s ) represents the leakage magnetic reluctance, i s R is the armature current. c =R c1 +R c2 R r R is the rotor reluctance. s For stator reluctance, R g It is an air gap magnetoresistive element.

[0060] Leakage reluctance R c (i s The magnitude of ) will change accordingly with the change of operating conditions, and it can be seen from formula (4) that the leakage magnetic reluctance R c (i s The size of ) affects the size of the saliency rate.

[0061] Based on the above analysis, the leakage magnetic reluctance R c (i s ) is an important parameter affecting the controllability of magnetic flux.

[0062] Figure 4 It shows Figure 1 The diagram shows a portion of the structure and key parameters of the rotor of a flux-controlled hub motor.

[0063] Leakage reluctance R c (i s The formula is as follows:

[0064] (5)

[0065] In the formula, l c The length of the radial leakage magnetic path in the rotor rib is μ0, where μ0 is the free permeability, and μ0 equals 4π × 10⁻⁶. -7 H / m; μ r Where S is the relative permeability, S is the cross-sectional area of ​​the magnetic circuit, and B is the relative permeability. rib It is the magnetic flux density in the rotor ribs, μ s (B rib ω is the permeability of the rotor silicon steel. rib ω is the circumferential length between the poles of the permanent magnet, representing the length of the total leakage flux path. rib Equal to 35mm; L aThis refers to the motor shaft length, typically 45mm, C. d C represents the radial distance from the outer edge of the trapezoidal magnetic barrier to the outer edge of the rotor, and C represents the width of the inter-pole leakage magnetic path. b ΔB represents the radial distance from the outer edge of the trapezoidal magnetic barrier to the outer arc-shaped permanent magnet, and represents the width of the self-leaking magnetic path; ΔB represents the degree of change in magnetic induction intensity, and ΔH represents the degree of change in magnetic field intensity.

[0066] Magnetic flux density varies under different operating conditions, therefore the permeability μ of the rotor silicon steel is closely related to magnetic flux density. s (B rib ) has also changed.

[0067] Under low-speed, heavy-load conditions, the permeability μ of the rotor silicon steel is... s (B rib ) _load The formula is as follows:

[0068] (6)

[0069] In the formula, t is a proportionality coefficient, which is related to the degree of magnetic circuit saturation and the magnetic flux regulation capability. At the operating point (speed 600 rpm, torque 20 Nm), t is taken as 15. At this time, the extreme value of leakage magnetic reluctance R under low-speed heavy-load conditions is... c_load for:

[0070] (7)

[0071] In the above formula, l c_load It is the length limit of the radial leakage magnetic path in the rotor rib under low-speed heavy-load conditions.

[0072] Under high-speed, light-load conditions, the relative permeability μ s (B rib ) _criuse The formula is as follows:

[0073] (8)

[0074] In the formula, k is a proportionality coefficient, which is related to the degree of magnetic circuit saturation and the magnetic flux regulation capability. At the operating point (speed 2400 rpm, torque 10 Nm), k is taken as 32. At this time, the extreme value of leakage magnetic reluctance R under high-speed, light-load operating conditions is... c_cruise for:

[0075] (9)

[0076] In the above formula, l c_cruise It is the length limit of the radial leakage magnetic path in the rotor rib under high-speed and light-load conditions.

[0077] Air gap reluctance R g This can be expressed as:

[0078] (10)

[0079] In the formula, g is the air gap length, taken as 1 mm, ω g It is the arc length corresponding to a pair of poles, taken as 91mm;

[0080] According to formula (2), in order to enhance the controllability of magnetic flux under different operating conditions, it is necessary to simultaneously increase the d-axis flux linkage ψ under low-speed conditions. d+ Reduce d-axis flux linkage ψ under high-speed conditions d .

[0081] Air gap reluctance R g The relationship between leakage flux and magnetic reluctance under various operating conditions is as follows:

[0082] (11)

[0083] therefore,

[0084] (12)

[0085] According to formulas (7), (9) and (10), the length l of the radial leakage magnetic path in the rotor rib can be obtained. c Length limit l under low-speed heavy-load conditions c_load Length limit for high-speed light-load conditions l c_cruise .

[0086] (13)

[0087] also

[0088] (14)

[0089] In the formula, m1 and m2 are weighting coefficients, which are determined by the percentage of the working conditions, where m1 is the proportion of low-speed working conditions to the total working conditions, and m2 is the proportion of high-speed working conditions to the total working conditions.

[0090] Based on formulas (5), (13), and (14), the following formula can be obtained:

[0091] (15)

[0092] Considering the domestic electric vehicle usage scenario, in one embodiment of the present invention, m1 is 40% and m2 is 60%.

[0093] Based on the above analysis, m1 is taken as 40%, m2 as 60%, g as 1mm, and ω... g Take 91mm, k = 34, t = 15, ω ribTake 35mm; based on the design method for enhancing magnetic flux controllability, substituting into formula (15), we can determine C. b +C d =8mm, then select the appropriate size according to the mechanical structure, C b =3mm, C d =5mm.

[0094] Design the long side B of the trapezoidal magnetic barrier for the motor. a =22mm, short side B b =18.2mm, length L of the arc-shaped permanent magnet pm =25.1mm, width H pm =4mm, simulated using Ansys software, the flux controllability curves under different operating conditions are as follows: Figure 5 As shown, the torque and power envelopes under all operating conditions are as follows: Figure 6 As shown.

[0095] See Figure 5 It can be seen that when the motor is in a "low-speed heavy-load" operating condition, as the q-axis armature current increases, the d-axis flux linkage ψ of the flux-controlled hub motor increases. d+ Significantly increased. For example, when i q At 30A, the flux controllability M of the flux-controlled hub motor is... l The value is 41.1%, indicating that the flux-controlled hub motor has strong flux controllability, which helps to improve output torque. When the motor is under "high-speed, light-load" operating conditions, the d-axis flux linkage ψ of the flux-controlled hub motor... d- With -i d The fact that the value decreases as the value increases indicates that the flux-controlled hub motor has more magnetic leakage and stronger flux control capability.

[0096] See Figure 6 As can be seen, the constant power of the flux-controlled hub motor is 4kW, which can meet the design requirements; and under a load capacity of 12Nm, the maximum speed of the flux-controlled hub motor reaches 6000r / min, which indicates that the flux-controlled hub motor has a wider speed range due to the design method that combines inter-pole leakage flux and self-leakage flux.

[0097] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A flux-controlled hub motor, characterized in that, The magnetic flux controllable wheel hub motor comprises: a stator; a rotor coaxially arranged outside the stator; m pieces of trapezoidal magnetic barriers, m groups of double-layer arc-shaped permanent magnets and m groups of double-layer arc-shaped magnetic barriers are alternately arranged in the circumference inside the rotor, m is an integer greater than 3; the center of the trapezoidal magnetic barrier is located on the d-axis, and each trapezoidal magnetic barrier does not contact the outer edge of the rotor; the double-layer arc-shaped magnetic barrier comprises two layers of arc-shaped magnetic barriers with the same structure, and the center of the arc-shaped magnetic barrier is located on the q-axis; the double-layer arc-shaped permanent magnet comprises two layers of arc-shaped permanent magnets with the same structure, one end of the arc-shaped permanent magnet contacts the end of the corresponding arc-shaped magnetic barrier, and the other end does not contact the end of the corresponding trapezoidal magnetic barrier; the arc-shaped permanent magnet is magnetized in the radial direction, the arc-shaped permanent magnets on the same pole are magnetized in the same direction, and the arc-shaped permanent magnets on adjacent poles are magnetized in opposite directions.

2. The flux-switching motor of claim 1, wherein The main magnetic circuit path of the magnetic flux controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-S pole of the outer arc-shaped permanent magnet of the adjacent pole-N pole of the inner arc-shaped permanent magnet of the adjacent pole-air gap-stator tooth-stator yoke-stator tooth-air gap-inner side of the rotor-S pole of the permanent magnet.

3. The flux-switching motor of claim 1, wherein The self-leakage magnetic circuit path of the magnetic flux controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-self-leakage magnetic bridge-S pole of the inner arc-shaped permanent magnet.

4. The flux-switching motor of claim 1, wherein, The inter-pole leakage magnetic circuit path of the magnetic flux controllable wheel hub motor is: S pole of the inner arc-shaped permanent magnet-N pole of the outer arc-shaped permanent magnet-outer side of the rotor-S pole of the outer arc-shaped permanent magnet of the adjacent pole-N pole of the inner arc-shaped permanent magnet of the adjacent pole-inner side of the rotor-S pole of the inner arc-shaped permanent magnet.

5. The flux-switching motor of claim 1, wherein, m=10。 6. The flux-switching motor of claim 1, wherein, The radial width of the arc-shaped magnetic barrier is the same.

7. The flux-switching motor of claim 1, wherein, The long side B of the trapezoidal magnetic barrier a is in a structural relationship with the short side B b of 1.5 ≤ (B a / B b ) ≤ 2.

5.

8. The flux-switching motor of claim 1, wherein, The low-speed operation (m1) of the flux-controlled hub motor accounts for 40% of the total operating conditions, and the high-speed operation (m2) accounts for 60% of the total operating conditions. The long side B of the trapezoidal magnetic barrier... a =22mm, the short side B of the trapezoidal magnetic barrier b =18.2mm, circumferential length L of the arc-shaped permanent magnet pm =25.1mm, radial width H pm =4mm, circumferential length ω between the poles of the arc-shaped permanent magnet rib =35mm, air gap length g=1mm, arc length ω corresponding to a pair of poles g =91mm, proportionality coefficient k is 34, proportionality coefficient t is 15, and the radial distance C from the outer edge of the trapezoidal magnetic barrier to the outer edge of the rotor is... d The radial distance C between the outer edge of the trapezoidal magnetic barrier and the outer arc-shaped permanent magnet b The sum is 8mm.

9. The flux-switching motor of claim 8, wherein, C d =5mm, C b =3mm.

10. A design method of a flux-controllable wheel motor according to any one of claims 1 to 8, characterized in that, The design method is that the radial distance C of the outer edge of the trapezoidal magnetic barrier from the outer edge of the rotor is determined according to the following formula d and the radial distance C of the outer edge of the trapezoidal magnetic barrier (8) from the outer layer arc-shaped permanent magnet b is determined according to the following formula: ， where g is the air gap length, ω g is the arc length corresponding to a pair of poles, μ0 is the vacuum permeability, ω rib is the circumferential length between the arc-shaped permanent magnet poles, m1 is the proportion of low-speed working condition to the whole working condition, m2 is the proportion of high-speed working condition to the whole working condition, and k and t are preset proportional coefficients.

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