Method for compensating air gap inconsistency of axial flux motor based on preset deformation

Abstract

The invention discloses a method for compensating air gap inconsistency of an axial flux motor based on preset deformation. The method comprises the following steps: (1) obtaining the magnetic pole area Sm of a permanent magnet; (2) establishing a data model of the magnetic flux force F and the air gap g; (3) establishing a data model of rotor yoke deflection f and magnetic flux force F; (4) according to the permanent magnet magnetic pole area Sm in the step (1), the data model of the magnetic flux force F and the air gap g in the step (2) and the data model of the rotor yoke deflection f and the magnetic flux force F in the step (3), deducing the relation between the air gap f and the rotor yoke deflection g; (5) correcting the deflection f of the rotor yoke in processing parameters, and processing the rotor yoke with pre-deformation; and (6) the axial magnetic flux motor with the pre-deformation rotor yoke is powered on to operate, and under the acting force of magnetic flux force, the rotor yoke deforms reversely, so that air gaps are kept consistent and uniform in the power-on operation process. According to the invention, the air gap change value is accurately predicted, and the air gap uniformity is ensured.

Description

Technical Field

[0001] The invention relates to a method for compensating for inconsistent air gaps of axial flux motors, belonging to the technical field of air gap compensation of axial flux motors. Background Art

[0002] The axial flux motor converts electrical energy and mechanical energy by generating a magnetic field between the stator and the rotor yoke. Figure 1 As shown, it includes a rotor and a stator 1. The rotor includes a yoke and a magnetic pole. The yoke is an important structure in the magnetic circuit of the motor. It is composed of two metal plates, a rotor yoke 3 and a rotor yoke 5. When the two move relative to each other in the alternating magnetic field, electromagnetic force is generated between the two and they attract each other. The rotor yoke 3 and the rotor yoke 5 are respectively arranged on the outside of the stator 1, and the patch type permanent magnet pole 2 is arranged on the inside of the rotor yoke 3, and the patch type permanent magnet pole 4 is arranged on the inside of the rotor yoke 5 to form a rotor. The two rotor yokes are axially positioned and fixed by a positioning body 6. Figure 1 Where H is the thickness of the rotor yoke, R o is the outer radius of the rotor yoke. The structure of the permanent magnet pole 2 in the axial flux motor is as follows Figure 2 As shown, it is a ring structure, where D o is the outer diameter of the permanent magnet pole (the largest diameter on the outside), D i is the inner diameter of the permanent magnet pole (the diameter of the smallest inner hole), S m is the area of ​​the permanent magnet pole. In an axial flux motor with two rotor yokes 3 and one stator 1, the gap between the stator and the permanent magnet pole is the air gap g. In this motor, the smaller the air gap g, the more stable the structure, the more stable the magnetic flux of the motor, and the more stable the magnetic field force generated.

[0003] However, during operation, there are forces between the permanent magnets of the rotor and between the stator windings, which may cause the air gap to change due to the forces between the magnets. Figure 3 As shown in the figure, the change makes the air gap uneven, causing fluctuations in the motor power and electromagnetic performance, affecting the stability and safety performance of the motor. When the air gap is uneven to a certain extent, it may even cause friction between the motor stator and rotor, causing a motor "sweeping" accident, or even burning the motor.

[0004] In the prior art, the air gap of an axial flux motor is generally an empirical value, which is determined based on experience. If the air gap value is too large, the rated efficiency of the motor will be reduced, and if the air gap value is too small, there is a risk of motor failure. Although thickening the yoke can offset the fluctuation of the air gap change value, it increases the motor's rotational inertia.

[0005] There is no research result on the air gap of axial flux motor, nor research data on air gap and material CNC machining. The existing technology does not take into account the variable problem and has low efficiency. Or the deformation is compensated by increasing the thickness of the rotor yoke, which increases the rotor's rotational inertia and manufacturing cost. Summary of the invention

[0006] In view of the problems existing in the existing air gap determination technology of an axial flux motor, the present invention provides a method for compensating for the inconsistent air gap of an axial flux motor based on a preset deformation amount, which can accurately predict the change value of the air gap and ensure the uniformity of the air gap.

[0007] The method of compensating the inconsistent air gap of an axial flux motor based on a preset deformation amount of the present invention comprises the following steps:

[0008] (1) According to the design parameters of the permanent magnet poles in the axial flux motor, the permanent magnet pole area Sm is obtained;

[0009] (2) Establishing a data model of magnetic flux force F and air gap g;

[0010] (3) Establishing a data model of rotor yoke disturbance f and magnetic flux force F;

[0011] (4) according to the data model of the permanent magnet pole area Sm in step (1), the magnetic flux force F and the air gap g in step (2), and the data model of the rotor yoke disturbance f and the magnetic flux force F in step (3), the relationship between the air gap f and the rotor yoke disturbance g is derived;

[0012] (5) The rotor yoke disturbance f is corrected in the processing parameters to produce a rotor yoke with a pre-deformation.

[0013] (6) The axial flux motor with a pre-deformed rotor yoke is powered on and operated. Under the action of the magnetic flux force, the rotor yoke is reversely deformed, so that the air gap remains consistent and uniform during the power-on operation.

[0014] The permanent magnet pole area S in step (1) m According to the following formula:

[0015] S m =π×(D O 2 -D i 2 ) / 4;

[0016] Where:

[0017] D O is the outer diameter of the permanent magnet pole, in m;

[0018] D i It is the inner diameter of the permanent magnet pole, in meters.

[0019] The data model relationship between the magnetic flux force and the air gap in step (2) is:

[0020] F=B 2 ×μ 0 ×S m (2×π×g 2 );

[0021] Where:

[0022] F is the magnetic flux force (magnetic force or repulsion), unit N;

[0023] B is the magnetic induction intensity of the permanent magnet pole, unit is T;

[0024] μ 0 is the vacuum permeability (4*π*10 -7 ), unit: H / m;

[0025] S m is the permanent magnet pole area, unit: m 2 ;

[0026] g is the air gap, unit is m.

[0027] The model relationship between the rotor yoke disturbance f and the magnetic flux force F data in step (3) is:

[0028]

[0029] in:

[0030] f is the rotor yoke disturbance, unit: m;

[0031] K is the material coefficient of the rotor yoke;

[0032] F b is the force on the plane (F b =F (the force is consistent with the magnetic flux force (magnetic force or repulsion force) in magnitude and direction), unit: N;

[0033] R o is the outer radius of the rotor yoke, in m;

[0034] E is the elastic modulus of the rotor yoke, in N / m 2 ;

[0035] H is the thickness of the rotor yoke, in m;

[0036] (4) according to the data model of the permanent magnet pole area Sm in step (1), the magnetic flux force F and the air gap g in step (2), and the data model of the rotor yoke disturbance f and the magnetic flux force F in step (3), the relationship between the air gap f and the rotor yoke disturbance g is derived;

[0037] The relationship between the air gap f and the rotor yoke disturbance g in step (4) is:

[0038]

[0039] Let k d =D i / D o , represents the ratio of inner and outer diameters of permanent magnet poles;

[0040] Let C = K × B 2 ×μ 0 ×(1-k d 2 ) / (128×E×H 3 ), which represents the comprehensive constant of the design parameters of the axial flux motor;

[0041] Then f=C*D o 4 / g.

[0042] The relationship between the rotor yoke disturbance f and the pre-deformation in step (5) is:

[0043] θ=arctan(f / (R o -D i / 2));

[0044] R o is the radius of the rotor yoke (that is, the radius of the permanent magnet pole, R o =D o / 2);

[0045] θ is the processing angle corresponding to the pre-deformation amount;

[0046] The machine tool (machining center) prepares a machining program according to the angle θ and processes the rotor yoke.

[0047] The present invention accurately predicts the change value of the air gap and ensures that the air gap is uniform. The change value of the air gap is predicted based on the parameters of the rotor yoke, stator, and magnet of the axial flux motor, and the accurate relationship between the deformation disturbance of the rotor yoke of the axial flux motor and the air gap is determined. The predicted change value of the air gap is fed back to the processing parameters that need to be corrected in the actual process, providing a basis for producing a rotor yoke with a processing allowance, and producing a motor that can ensure a uniform air gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the structural principle of the axial flux motor.

[0049] Figure 2 It is a schematic diagram of the magnetic pole structure in an axial flux motor.

[0050] Figure 3Schematic diagram of air gap deformation in an axial flux motor.

[0051] Figure 4 It is a flow chart of a method of compensating for inconsistent air gap of an axial flux motor based on a preset deformation amount according to the present invention.

[0052] Figure 5 It is a schematic diagram of the relationship between the disturbance f and the subsequent processing pre-deformation.

[0053] Figure 6 This is the displacement deformation diagram of the rotor yoke after the simulated disturbance correction.

[0054] Figure 7 This is the simulated stress deformation diagram of the rotor yoke after disturbance correction.

[0055] In the figure: 1. stator, 2. permanent magnet poles, 3. rotor yoke, 4. permanent magnet poles, 5. permanent magnet poles, 6. positioning body; g. air gap, H. thickness of rotor yoke, D o .Outer diameter of permanent magnet pole, D i .Inner diameter of permanent magnet pole, R o .Radius of the rotor yoke, S m .Permanent magnet pole area. DETAILED DESCRIPTION

[0056] The problem solved by the present invention is how to predict the change of the air gap based on the parameters of the rotor yoke, stator 1 and permanent magnet poles of different axial flux motors, and feed back the predicted change of the air gap to the processing parameters that need to be corrected in the actual process, so as to produce a motor that can ensure a uniform air gap g.

[0057] The layout characteristics of the axial flux motor determine that theoretically the magnetic field force of the motor is evenly distributed on the same radius of each axial section, and the permanent magnet pole patches are on the rotor yoke, so the material deformation of the rotor yoke 3 is the determining factor of the change in the motor air gap.

[0058] After finding the mathematical model of the air gap g and the material deformation of the rotor yoke, the results of the mathematical model are substituted into the production and processing parameters for correction, and a rotor yoke 3 with pre-deformation is processed. After the patch assembly and the motor is powered on, the rotor yoke undergoes reverse deformation under the action of the magnetic flux force, so that the air gap rotor yoke remains consistent and uniform during the final power-on operation.

[0059] The air gap value is calculated through the mathematical model of magnetic flux force and air gap, and the reserved deformation is processed when machining the rotor yoke to ensure that the air gap remains consistent under the influence of the force during actual power-on operation after the motor with reserved deformation is assembled.

[0060] Figure 4The present invention provides a process of a method for compensating for inconsistent air gaps of an axial flux motor based on a preset deformation amount, which specifically includes the following steps.

[0061] 1. Obtain the permanent magnet pole parameters of the axial flux motor and obtain the permanent magnet pole area Sm

[0062] The outer diameter D of the permanent magnet pole O and inner diameter D i are the design parameters of the axial flux motor. Based on these two parameters, its area S can be obtained m . Magnetic flux force F, air gap g, etc. are the design parameters of axial flux motor.

[0063] The permanent magnet pole area S m According to the following formula:

[0064] S m =π×(D O 2 -D i 2 ) / 4;

[0065] Where:

[0066] D O is the outer diameter of the permanent magnet pole (the diameter at the largest point on the outside, see Figure 2 ), unit: m;

[0067] D i is the inner diameter of the permanent magnet pole (the diameter of the smallest part of the inner hole, see Figure 2 ), unit: m.

[0068] 2. Use the magnetic force of the permanent magnet pole to obtain a data model with magnetic flux force and air gap

[0069] The data model relationship between magnetic flux force and air gap is:

[0070] F=B 2 ×μ 0 ×S m (2×π×g 2 );

[0071] Where:

[0072] F is the magnetic flux force (magnetic force or repulsion), unit N;

[0073] B is the magnetic induction intensity of the permanent magnet pole, unit is T;

[0074] μ 0 is the vacuum permeability (4*π*10 -7 ), unit: H / m;

[0075] S mis the permanent magnet pole area (see Figure 2 , the permanent magnet pole is a ring-shaped disk), unit: m 2 ;

[0076] g is the air gap, unit is m.

[0077] 3. Establish the data model of rotor yoke disturbance and magnetic flux force based on material mechanics calculation

[0078] Deflection is the linear displacement of the axis of a rod in a direction perpendicular to the axis or the linear displacement of the mid-surface of a plate or shell in a direction perpendicular to the mid-surface when subjected to force or non-uniform temperature changes.

[0079] The mechanical formula of the rotor yoke disturbance f is:

[0080]

[0081] in:

[0082] f is the rotor yoke disturbance, unit: m;

[0083] K is the material coefficient of the rotor yoke;

[0084] F b is the force on the plane, F b =F, the force is consistent with the magnitude and direction of the magnetic flux force F, unit N;

[0085] R o is the outer radius of the rotor yoke (see Figure 1 ), unit: m;

[0086] E is the elastic modulus of the rotor yoke, in N / m 2 ;

[0087] H is the thickness of the rotor yoke (see Figure 1 ), unit: m;

[0088] 4. Determine the relationship between the air gap f and the rotor yoke disturbance g

[0089] According to the above three formulas F=B 2 ×μ 0 ×S m(2×π×g 2 ), S m =π×(D O 2 -D i 2 ) / 4 and And F b =F, and the relationship between g and f is derived:

[0090]

[0091] Let k d =Di / D o , represents the ratio of inner and outer diameters of permanent magnet poles;

[0092] Let C = K × B 2 ×μ 0 ×(1-k d 2 ) / (128×E×H 3 ), which represents the comprehensive constant of the design parameters of the axial flux motor;

[0093] Then f=C*D o 4 / g.

[0094] According to the above formula f=C*D o 4 / g, it can be concluded that the rotor yoke disturbance f is related to the outer diameter D of the permanent magnet pole o It is directly proportional to the fourth power of .

[0095] The greater the motor power, the larger the outer diameter D of the permanent magnet poles. o The larger the rotor yoke diameter (or rotor yoke diameter), the greater the rotor yoke disturbance f (deformation).

[0096] 5. Substitute the rotor yoke disturbance f into the processing parameters of the machine tool (machining center), make corrections, and process the rotor yoke with pre-deformation.

[0097] The relationship between the rotor yoke disturbance f and the subsequent processing pre-deformation is as follows: Figure 5 shown.

[0098] Maximum disturbance f and permanent magnet pole outer diameter D o The corresponding processing angle θ is as follows:

[0099] tan(θ)=f / (R o -D i / 2); R o is the radius of the rotor yoke (that is, the radius of the permanent magnet pole, R o =D o / 2)

[0100] We get: θ = arctan(f / (R o -D i / 2));

[0101] The machining center (machine tool) processes the CNC molding according to the θ angle.

[0102] 6. The rotor yoke with pre-deformation is assembled with other components (stator 1, permanent magnet poles, etc.) into an axial flux motor and then powered on for operation. Under the action of the magnetic flux force, the rotor yoke is reversely deformed so that the air gap remains consistent and uniform during the power-on operation.

[0103] The method of the present invention calculates the accurate relationship between the deformation disturbance of the rotor yoke and the air gap of the axial flux motor, which provides a basis for subsequent production and processing allowance. Figure 6 and Figure 7 The simulation results of the method of the present invention are given. Figure 5 is the displacement deformation diagram of the rotor yoke after disturbance correction, Figure 7 It is the stress deformation diagram of the rotor yoke after disturbance correction.

[0104] It can be seen from the data in the two figures that, when the middle fixed point is set in the cantilever mechanical model of the 22KW motor rotor yoke, and the disk surface of the permanent magnet pole is fully and equally stressed, it can be seen that the disturbance deformation at the maximum diameter of the corrected rotor yoke is on the order of 0.3mm, and the stress is one order of magnitude lower than the yield force.

[0105] The method of the present invention is also applicable to various axial flux motors that need to predict the air gap variation to guide the production process adjustment, such as the following occasions:

[0106] 1. The connection method between the rotor yoke and the permanent magnet pole is not limited to the patch process. It can also be applied to inlay and mechanical connection. The disturbance under other methods is transformed into the disturbance deformation calculation under the calculation of comprehensive materials.

[0107] 2. In situations where axial magnetic flux is applied and air gap stability is required, this method can be used or the formula can be changed according to actual working conditions to deduce the relationship between the air gap and other known parameters.

[0108] 3. Although the influence of temperature field / gravity / eccentric force field is ignored, the empirical value of air gap is still converted into data that can be easily calculated.

[0109] 4. This method can be used for axial flux motors, whether they have a single-disk structure or a multi-disk structure, because they all have the problem of uneven air gap.

[0110] 5. It is not limited to the pre-deformation of the yoke, but also applicable to the pre-deformation of the magnet slot. The change of the deformation amount and thickness dimension is based on the formula derived from the present invention.

Claims

1. A method for compensating for air gap inconsistency in an axial flux motor based on a preset deformation, characterized in that: The following steps are involved: (1) Obtaining the permanent magnet pole parameters of the axial flux motor to obtain the permanent magnet pole area Sm; (2) Establishing a data model of magnetic flux force F and air gap g; (3) Establishing a data model of rotor yoke disturbance f and magnetic flux force F; (4) according to the data model of the permanent magnet pole area Sm in step (1), the magnetic flux force F and the air gap g in step (2), and the data model of the rotor yoke disturbance f and the magnetic flux force F in step (3), the relationship between the air gap f and the rotor yoke disturbance g is derived; (5) The rotor yoke disturbance f is corrected in the processing parameters to process a rotor yoke with a pre-deformation; (6) The axial flux motor with a pre-deformed rotor yoke is powered on and operated. Under the action of the magnetic flux force, the rotor yoke is reversely deformed, so that the air gap remains consistent and uniform during the power-on operation.

2. The method for compensating the air gap inconsistency of an axial flux motor based on a preset deformation amount according to claim 1 is characterized in that: The permanent magnet pole area S in step (1) m According to the following formula: S m =π×(D O 2 -D i 2 ) / 4; Where: D O is the outer diameter of the permanent magnet pole, in m; D i It is the inner diameter of the permanent magnet pole, in meters.

3. The method for compensating the air gap inconsistency of an axial flux motor based on a preset deformation amount according to claim 1 is characterized in that: The data model relationship between the magnetic flux force and the air gap in step (2) is: F=B 2 ×μ0×S m (2×π×g 2 ); Where: F is the magnetic flux force, in N; B is the magnetic induction intensity of the permanent magnet pole, unit is T; μ0 is the vacuum permeability, unit is H / m; S m is the permanent magnet pole area, unit: m 2 ; g is the air gap, unit is m.

4. The method for compensating the air gap inconsistency of an axial flux motor based on a preset deformation amount according to claim 1 is characterized in that: The model relationship between the rotor yoke disturbance f and the magnetic flux force F in step (3) is: in: f is the rotor yoke disturbance, unit: m; K is the material coefficient of the rotor yoke; F b is the force on the plane, in N; R o is the outer radius of the rotor yoke, in m; E is the elastic modulus of the rotor yoke, in N / m 2 ; H is the thickness of the rotor yoke, in meters.

5. The method for compensating the air gap inconsistency of an axial flux motor based on a preset deformation amount according to claim 1 is characterized in that: The relationship between the air gap f and the rotor yoke disturbance g in step (4) is: Let k d =D i / D o , represents the ratio of inner and outer diameters of permanent magnet poles; Let C = K × B 2 ×μ0×(1-k d 2 ) / (128×E×H 3 ), which represents the comprehensive constant of the design parameters of the axial flux motor; Then f=C*D o 4 / g.

6. The method for compensating the air gap inconsistency of an axial flux motor based on a preset deformation amount according to claim 1 is characterized in that: The relationship between the rotor yoke disturbance f and the pre-deformation in step (5) is: θ=arctan(f / (R o -D i / 2)); θ is the processing angle corresponding to the pre-deformation amount; R o is the radius of the rotor yoke.

Images