Design method of coreless stator axial magnetic flux permanent magnet motor

Abstract

The invention discloses a design method of a coreless stator axial magnetic flux permanent magnet motor. The method specifically comprises the following steps: firstly, determining a basic structure, a permanent magnet structure and performance demand parameters of the coreless stator axial magnetic flux permanent magnet motor; determining stator and rotor structure parameters of the motor according to the performance requirement parameters of the motor; establishing a simplified model of an internal magnetic circuit of the motor, determining excitation magnetic potential of the motor, and establishing a finite element dynamic simulation model of the coreless stator axial flux permanent magnet motor based on a Maxwell equation; and finally, comparing the finite element dynamic simulation result with the motor performance demand parameter, if the finite element dynamic simulation result does not meet the requirement, correcting the motor design structure parameter and the electromagnetic parameter, and re-determining the stator and rotor structure parameter of the motor until the finite element dynamic simulation result of the motor meets the motor performance demand parameter. The design cost of the coreless stator axial magnetic flux permanent magnet motor is reduced, the design period is shortened, and the design efficiency and the design precision are improved.

Description

Technical Field

[0001] The invention relates to the field of motor design, in particular to a design method for an iron-coreless stator axial flux permanent magnet motor. Background Art

[0002] At present, energy consumption and environmental pollution are becoming increasingly serious, and energy conservation and emission reduction have become a global issue. With the development of high-performance permanent magnet materials such as neodymium iron boron (NdFeB), their cost continues to decrease and their cost performance continues to improve. In view of this, it has become a trend to replace electromagnetic motors with permanent magnet motors with high power density, low energy loss and high reliability.

[0003] The coreless stator axial magnetic field permanent magnet motor is a new type of motor structure. For the traditional axial magnetic field permanent magnet synchronous motor, its stator and rotor cores are formed by stacking high magnetic permeability silicon steel sheets, which not only leads to a relatively large volume and mass of the motor, but also reduces the motor efficiency due to the iron loss in the stator and rotor silicon steel sheets. Therefore, the use of the stator core is eliminated, and the stator winding is fixed by epoxy resin casting, which greatly reduces the weight of the motor and eliminates the influence of the stator iron loss and the motor torque pulsation caused by the tooth slot. It has the advantages of high efficiency, high power density, compact axial structure, smooth operation, low noise, etc., and has broad application prospects in wind power generation, electric vehicles, aerospace and other fields.

[0004] Therefore, it is an urgent problem to be solved in this field to design the permanent magnet motor with axial magnetic field and coreless stator according to the actual performance requirements of the motor while taking into account the good output performance of the motor. Summary of the invention

[0005] The object of the present invention is to provide a design method for an iron-coreless stator axial flux permanent magnet motor with high design efficiency and design accuracy, low design cost and short design cycle.

[0006] The technical solution to achieve the purpose of the present invention is: a design method for an ironless stator axial flux permanent magnet motor, comprising the following steps:

[0007] Step 1, determining the basic structure and permanent magnet structure of the coreless stator axial flux permanent magnet motor;

[0008] Step 2, determining the performance requirement parameters of the ironless stator axial flux permanent magnet motor;

[0009] Step 3: Determine the stator and rotor structural parameters of the motor according to the performance requirement parameters of the motor;

[0010] Step 4: Establish a simplified model of the internal magnetic circuit of the motor and determine the excitation magnetic potential of the motor;

[0011] Step 5: Based on Maxwell's equations, establish a finite element dynamic simulation model of a coreless stator axial flux permanent magnet motor;

[0012] Step 6: Compare the finite element dynamic simulation results with the motor performance requirement parameters. If they do not meet the requirements, correct the motor design structure parameters and electromagnetic parameters, and repeat Steps 2 to 5 until the finite element dynamic simulation results of the motor meet the motor performance requirement parameters.

[0013] A coreless stator axial flux permanent magnet motor is prepared by the above design method.

[0014] Compared with the prior art, the present invention has the following remarkable advantages: (1) Determine the motor structure parameters based on the actual performance requirements of the coreless stator axial flux permanent magnet motor, and simulate and analyze the output performance of the designed permanent magnet synchronous motor by means of computer finite element simulation, and analyze and verify the motor structure parameters determined by the design method, reducing the possibility that the test prototype does not meet the design requirements in terms of performance output, dynamic characteristics and working efficiency, etc., and improving the motor design efficiency and design accuracy; (2) The method is simple and highly reliable, reducing the design cost of the coreless stator permanent magnet synchronous motor and shortening the design cycle. Description of the Drawings

[0015] Figure 1 is a schematic flow chart of the design method of a coreless stator axial flux permanent magnet motor of the present invention.

[0016] Figure 2 is a rotor structure diagram of the coreless stator axial flux permanent magnet motor designed in the embodiment of the present invention.

[0017] Figure 3 is a stator structure diagram of the coreless stator axial flux permanent magnet motor designed in the embodiment of the present invention.

[0018] Figure 4 is the per-phase steady-state equivalent circuit of the coreless stator axial flux permanent magnet motor designed in the embodiment of the present invention.

[0019] Figure 5 is the equivalent magnetic circuit diagram of the coreless stator axial flux permanent magnet motor designed in the embodiment of the present invention under load conditions.

[0020] Figure 6 is the NS magnetic circuit structure diagram of the coreless stator axial flux permanent magnet motor designed in the embodiment of the present invention. Detailed Embodiments

[0021] It is easy to understand that, according to the technical solution of the present invention, without changing the essential spirit of the present invention, those of ordinary skill in the art can imagine various embodiments of the present invention. Therefore, the following specific embodiments and the accompanying drawings are only illustrative descriptions of the technical solution of the present invention, and should not be regarded as all of the present invention or as a limitation or restriction on the technical solution of the present invention.

[0022] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention.

[0023] The following description of at least one exemplary embodiment is merely illustrative in nature and in no way serves as a limitation on the present invention or its application or use.

[0024] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the specification.

[0025] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0026] As Figure 1 shown, a design method for a coreless stator axial flux permanent magnet motor of the present invention includes the following steps:

[0027] Step 1, determine the basic structure and permanent magnet structure of the coreless stator axial flux permanent magnet motor;

[0028] Step 2, determine the performance requirement parameters of the coreless stator axial flux permanent magnet motor;

[0029] Step 3, according to the performance requirement parameters of the motor, determine the stator and rotor structure parameters of the motor;

[0030] Step 4, establish a simplified model of the internal magnetic circuit of the motor and determine the magnetomotive force of the motor;

[0031] Step 5, based on Maxwell's equations, establish a finite element dynamic simulation model of the coreless stator axial flux permanent magnet motor;

[0032] Step 6, compare the finite element dynamic simulation results with the motor performance requirement parameters. If they do not meet the requirements, correct the motor design structure parameters and electromagnetic parameters, and repeat steps 2 to 5 until the finite element dynamic simulation results of the motor meet the motor performance requirement parameters.

[0033] As a specific example, the basic structure of the ironless stator axial flux permanent magnet motor and the permanent magnet structure, that is, the basic structure of the single stator and double rotor motor and the permanent magnet structure of the NS magnetic circuit, are determined in step 1.

[0034] As a specific example, the performance requirement parameters of the ironless stator axial flux permanent magnet motor determined in step 2 include the number of phases m of the ironless stator axial flux permanent magnet motor, the rated voltage U of each phase N , the rated speed regulation range and the rated efficiency η. These performance parameters are determined according to the application scenario of the motor and the pre-designed requirements.

[0035] As a specific example, the stator and rotor structure parameters of the motor described in step 3 include the inner diameter of the motor stator, the outer diameter of the motor stator, the height of the stator teeth, the thickness of the stator disk, the air gap length, the volume of the permanent magnet, the inner diameter of the permanent magnet, the outer diameter of the permanent magnet, the number of permanent magnets per rotor and the number of turns of the winding.

[0036] As a specific example, according to the performance requirement parameters of the motor described in step 3, the stator and rotor structure parameters of the motor are determined as follows:

[0037] Step 3.1. Ideally, the voltage of each phase winding of the motor is a sine wave, and the effective value of the electromotive force of each phase is:

[0038]

[0039] Among them, E φ is the effective value of the electromotive force of each phase; f is the frequency; N is the number of turns connected in series per phase of the winding; k ω1 is the winding coefficient; φ is the effective value of the air gap axial magnetic flux that varies sinusoidally under each pole of this motor; α i is the calculated pole arc coefficient; B δ is the air gap magnetic density; D out is the outer diameter of the motor, D in is the inner diameter of the motor; b i is the calculated pole arc width; τ is the pole pitch; B av is the average magnetic flux density;

[0040] The electric loading of the motor changes with the radius. The conductors are denser towards the center of the motor, and the electric loading is greater; when the electric loading is too high, the temperature at the inner diameter will reach the threshold first. Therefore, when selecting the electric loading of the motor, the electric loading at the minimum radius of the motor should be considered, that is:

[0041]

[0042] Among them, m is the number of phases of the ironless stator axial flux permanent magnet motor; I φ is the effective value of the current of each phase winding; D in is the size of the inner diameter of the motor;

[0043] Ideally, the motor output power P em is:

[0044]

[0045] Calculate the outer diameter of the motor through the relationship between the rated power of the motor and the outer diameter of the motor. The calculation formula is:

[0046]

[0047] where D out is the outer diameter of the motor, k ω is the winding coefficient; α i is the calculated pole arc coefficient, that is, the ratio of the calculated pole arc width to the pole pitch; B δ is the maximum value of the air-gap magnetic flux density, η is the rated efficiency of the motor, is the power factor, A max is the electric loading at the minimum radius of the motor, γ is the ratio of the inner diameter to the outer diameter of the motor, k 0 is the potential coefficient, P em is the rated power of the motor;

[0048] Step 3.2: Select appropriate ratios of the inner diameter to the outer diameter γ of the motor, the number of turns connected in series per phase of the winding, the air-gap magnetic flux density, the calculated pole arc coefficient, the pole arc coefficient, the leakage magnetic coefficient of the motor, and the air-gap magnetic flux density distribution coefficient according to actual requirements and experience, and calculate the inner diameter D in of the motor. The calculation formula is:

[0049] D in = γD out

[0050] Step 3.3: Select appropriate permanent magnet materials, air-gap length δ, and thickness h M of the motor magnetic steel, and determine the volume of the permanent magnet. The calculation formula is:

[0051]

[0052] where V m is the volume of the permanent magnet, A m is the magnetic flux area provided by the permanent magnet, h M is the thickness of the motor magnetic steel, B δ is the air-gap magnetic flux density, A δ is the effective area of each pole air-gap, B m is the total magnetic flux density of the permanent magnet, δ is the air-gap length, μ 0 is the vacuum permeability, h M is the thickness of the motor magnetic steel, V δ is the air-gap volume, E m is the magnetic energy product at the working point.

[0053] As a specific example, in step 4, a simplified model of the internal magnetic circuit of the motor is established to determine the exciting magnetomotive force of the motor.

[0054] Step 4.1: Without considering magnetic saturation, neglecting armature reaction and neglecting the magnetic potential difference of the yoke, the idea of "field-to-circuit" is adopted to simplify the internal magnetic circuit of the motor and establish a simplified magnetic circuit model.

[0055] Not considering magnetic saturation means setting the rotor yoke on the main magnetic path, that is, the back yoke part of the motor is in a magnetically unsaturated state.

[0056] Neglecting armature reaction means setting the armature without slots and iron core, and its magnetic properties can be regarded as equivalent to air when analyzing the magnetic circuit or magnetic field.

[0057] Neglecting the magnetic potential difference of the yoke means setting the magnetic resistance of the rotor yoke to be very small relative to air, and the magnetic potential difference in the yoke can be ignored.

[0058] If you want to analyze and calculate the steady-state performance of a coreless axial-flux permanent magnet motor, you need to establish an equivalent circuit of the motor, as Figure 4 shown, where R 1 is the stator resistance, X 1 is the stator leakage reactance, E f is the induced electromotive force of the stator winding, E i is the root mean square value of the phase voltage, V 1 is the terminal voltage.

[0059] In a permanent magnet motor, three-phase currents will be generated in the winding coils under load conditions, and a three-phase resultant magnetomotive force F a will be generated, which will in turn affect the air-gap magnetic field. This process is the armature reaction; the load magnetic circuit model is as Figure 5 shown. Since the equivalent air-gap length of the coreless axial-flux permanent magnet motor is relatively large and the armature reaction is not obvious, only the no-load equivalent magnetic circuit model is considered.

[0060] The established simplified magnetic circuit model is:

[0061]

[0062] Among them, σ is the leakage coefficient; φ m is the total magnetic flux of this motor; φ δ is the main air-gap magnetic flux of the magneto; A m is the magnetic flux area per pole corresponding to the permanent magnet; A δ is the effective area of the air-gap per pole; B m is the total magnetic flux density of the permanent magnet; B δ is the air-gap magnetic flux density; α p is the pole arc coefficient; α i is the calculated pole arc coefficient; p is the number of pole pairs; Din is the inner diameter; D out is the outer diameter; K F is the air-gap magnetic density distribution coefficient;

[0063] Step 4.2, the structure of the NS magnetic circuit is as Figure 6 described. According to the simplified magnetic circuit model of the motor, for a permanent magnet motor with an axially magnetized ironless stator, the following relationship can be obtained:

[0064] B = μ 0 (M + H)

[0065] where B is the magnetic induction intensity; M is the magnetization intensity; H is the magnetic field intensity.

[0066] From the principle of magnetic flux continuity, it can be known that

[0067] A m B m = σA δ B δ

[0068] where σ is the leakage magnetic coefficient; A m is the per-pole magnetic flux area corresponding to the permanent magnet; A δ is the effective area of the per-pole air gap; B m is the total magnetic density of the permanent magnet; B δ is the air-gap magnetic density;

[0069] The relationship between the magnetic field intensity and the magnetic flux density is:

[0070] B m = -μ 0 μ r H m + B r

[0071] where μ 0 is the vacuum magnetic permeability; μ r is the relative magnetic permeability of the magnet steel; B r is the remanent magnetization of the magnet steel;

[0072] When calculating, let the pole arc coefficient be equal to the calculated pole arc coefficient. To sum up, the air-gap magnetic flux density is:

[0073]

[0074] where μ r is the relative magnetic permeability of the magnet steel, B r is the remanent magnetization of the magnet steel, K F is the air-gap magnetic density distribution coefficient, and σ is the leakage magnetic coefficient;

[0075] Although ignoring the leakage flux and simplifying the axially distributed magnetic flux in three dimensions to a two-dimensional problem at the average radius will introduce errors, it makes the complex magnetic field problem analyzable. That is, factors such as the remanence magnetic density of the permanent magnet, leakage flux coefficient, magnetic density waveform coefficient, ratio of air gap to magnetization intensity, etc. determine the magnetic flux density in the air gap of the motor.

[0076] The present invention also provides a coreless stator axial flux permanent magnet motor, which is prepared by the above design method.

[0077] The following further elaborates on the present invention in detail with reference to the accompanying drawings and specific embodiments.

[0078] Embodiment

[0079] As Figure 1 shown, the present embodiment provides a design method for a coreless stator axial flux permanent magnet motor, including the following steps:

[0080] Step 1: Determine the basic structure of the coreless stator axial flux permanent magnet motor and the permanent magnet structure, that is, the basic structure of a single stator double rotor motor and the permanent magnet structure of the NS magnetic circuit.

[0081] Step 2: Determine the performance requirement parameters of the coreless stator axial flux permanent magnet motor, including the number of phases m of the coreless stator axial flux permanent magnet motor, the rated voltage U N per phase, the rated speed regulation range, and the rated efficiency η. These performance parameters are manually determined by the designer according to the application scenario of the motor and the pre-designed requirements.

[0082] 4. According to the design method of the coreless stator axial flux permanent magnet motor described in claim 1, characterized in that the stator and rotor structure parameters of the motor in step 3 include the inner diameter of the motor stator, the outer diameter of the motor stator, the height of the stator teeth, the thickness of the stator disk, the air gap length, the volume of the permanent magnet, the inner diameter of the permanent magnet, the outer diameter of the permanent magnet, the number of permanent magnets per rotor, and the number of turns of the winding. Specifically as follows:

[0083] Step 3.1: Ideally, the voltage of each phase winding of the motor is a sine wave, and the effective value of the electromotive force per phase is:

[0084]

[0085] where E φ is the effective value of the electromotive force per phase; f is the frequency; N is the number of turns in series per phase of the winding; k ω1 is the winding coefficient; φ is the effective value of the axially distributed air gap magnetic flux that varies sinusoidally under each pole of this motor; α i is the calculated pole arc coefficient; B δ is the air gap magnetic density; D out is the outer diameter of the motor, D inis the inner diameter of the motor; b i is for calculating the pole arc width; τ is the pole pitch; B av is the average magnetic flux density.

[0086] The linear load of the motor varies with the radius. The closer to the center of the motor, the denser the conductors and the greater the electrical load. When the electrical load is too high, the temperature at the inner diameter will reach the threshold first. Therefore, when selecting the electrical load of the motor, the electrical load at the minimum radius of the motor should be considered, that is:

[0087]

[0088] where m is the number of phases of the stator coreless axial flux permanent magnet motor; I φ is the effective value of the current of each phase winding; D in is the size of the inner diameter of the motor;

[0089] Ideally, the output power P of the motor em is:

[0090]

[0091] Calculate the outer diameter of the motor through the relationship between the output power of the motor and the outer diameter of the motor. The calculation formula is:

[0092]

[0093] where D out is the outer diameter of the motor, k ω is the winding coefficient, α i is the calculated pole arc coefficient, that is, the ratio of the calculated pole arc width to the pole pitch, B δ is the maximum value of the air-gap magnetic flux density, η is the rated efficiency of the motor, is the power factor, A max is the electrical load at the minimum radius of the motor, γ is the ratio of the inner and outer diameters of the motor, k 0 is the potential coefficient, P em is the rated power of the motor;

[0094] Step 3.2. Select appropriate ratios of the inner and outer diameters of the motor γ, the number of turns connected in series per phase of the winding, the air-gap magnetic flux density, the calculated pole arc coefficient, the pole arc coefficient, the leakage magnetic coefficient of the motor, and the air-gap magnetic flux density distribution coefficient according to actual requirements and experience, and calculate the inner diameter D of the motor in , and the calculation formula is:

[0095] D in = γD out

[0096] Step 3.3. Select appropriate permanent magnet materials, air-gap lengths δ and motor magnet thicknesses h M , and determine the volume of the permanent magnet. The calculation formula is:

[0097]

[0098] Among them, V m is the volume of the permanent magnet, A m is the magnetic flux area provided by the permanent magnet, h M is the thickness of the motor magnet steel, B δ is the air-gap magnetic density, A δ is the effective area of each pole air-gap, B m is the total magnetic density of the permanent magnet, δ is the air-gap length, μ 0 is the permeability of free space, h M is the thickness of the motor magnet steel, V δ is the air-gap volume, E m is the magnetic energy product at the operating point.

[0099] Step 4: Establish a simplified model of the internal magnetic circuit of the motor and determine the exciting magnetomotive force of the motor;

[0100] Step 4.1: Without considering magnetic saturation, neglecting armature reaction and neglecting the magnetic potential difference of the yoke, use the idea of "field to circuit" to simplify the internal magnetic circuit of the motor and establish a simplified magnetic circuit model;

[0101] Not considering magnetic saturation means setting the rotor yoke on the main magnetic path, that is, the back yoke part of the motor is in a magnetically unsaturated state;

[0102] Neglecting armature reaction means setting the armature without slots and iron core, and its magnetic properties can be regarded as equivalent to air when analyzing the magnetic circuit or magnetic field;

[0103] Neglecting the magnetic potential difference of the yoke means setting the magnetic resistance of the rotor yoke to be very small relative to air, and the magnetic potential difference in the yoke can be neglected;

[0104] If you want to analyze and calculate the steady-state performance of a coreless axial-flux permanent magnet motor, you need to establish an equivalent circuit of the motor, as Figure 4 shown, where R 1 is the stator resistance, X 1 is the stator leakage reactance, E f is the induced electromotive force of the stator winding, E i is the root mean square value of the phase voltage, V 1 is the terminal voltage;

[0105] When the permanent magnet motor is under load, the winding coils will generate three-phase currents and generate a three-phase synthetic magnetomotive force F a which will then affect the air-gap magnetic field, and this process is the armature reaction; the load magnetic circuit model is as Figure 5 shown. Since the equivalent air-gap length of the coreless axial-flux permanent magnet motor is relatively large and the armature reaction is not obvious, only the no-load equivalent magnetic circuit model is considered;

[0106] The established simplified magnetic circuit model is as follows:

[0107]

[0108]

[0109] Among them, σ is the leakage magnetic coefficient; φ m is the total magnetic flux of this motor; φ δ is the main magnetic flux of the air gap of the magneto; A m is the magnetic flux area per pole corresponding to the permanent magnet; A δ is the effective area of the air gap per pole; B m is the total magnetic flux density of the permanent magnet; B δ is the air gap magnetic flux density; α p is the pole arc coefficient; α i is the calculated pole arc coefficient; p is the number of pole pairs; D in is the inner diameter; D out is the outer diameter; K F is the air gap magnetic flux density distribution coefficient;

[0110] Step 4.2. The structure of the NS magnetic circuit is as Figure 6 described. According to the simplified magnetic circuit model of the motor, for a permanent magnet motor with an axially magnetized ironless stator, the following relationships can be obtained:

[0111] B = μ 0 (M + H)

[0112] Among them, B is the magnetic induction intensity; M is the magnetization intensity; H is the magnetic field intensity.

[0113] From the principle of magnetic flux continuity, it can be known that

[0114] A m B m = σA δ B δ

[0115] Among them, σ is the leakage magnetic coefficient; A m is the magnetic flux area per pole corresponding to the permanent magnet; A δ is the effective area of the air gap per pole; B m is the total magnetic flux density of the permanent magnet; B δ is the air gap magnetic flux density;

[0116] The relationship between the magnetic field intensity and the magnetic flux density is:

[0117] B m = -μ 0 μ r H m + B r

[0118] Among them, μ0 is the permeability of free space; μ r is the relative permeability of the permanent magnet; B r is the remanent magnetization of the permanent magnet;

[0119] When calculating, let the pole arc coefficient be equal to the calculated pole arc coefficient. Based on the above, the air-gap flux density can be obtained as:

[0120]

[0121] where μ r is the relative permeability of the permanent magnet, B r is the remanent magnetization of the permanent magnet, K F is the air-gap magnetic density distribution coefficient, and σ is the leakage magnetic coefficient;

[0122] Although ignoring the leakage magnetic and simplifying the axial magnetic flux with a three-dimensional distribution to a two-dimensional problem at the average radius will introduce errors, it makes the complex magnetic field problem analyzable. That is, factors such as the remanent magnetic density of the permanent magnet, the leakage magnetic coefficient, the magnetic density waveform coefficient, and the ratio of the air gap to the magnetization intensity determine the air-gap flux density of the motor.

[0123] Step 5: Based on Maxwell's equations, establish a finite element dynamic simulation model of the coreless stator axial-flux permanent magnet motor;

[0124] Step 6: Compare the finite element dynamic simulation results with the motor performance requirement parameters. If they do not meet the requirements, correct the motor design structure parameters and electromagnetic parameters, and repeat Steps 2 to 5 until the finite element dynamic simulation results of the motor meet the motor performance requirement parameters.

[0125] Through the method provided by the present invention, first determine the motor structure parameters based on the actual performance requirements of the coreless stator axial-flux permanent magnet motor, such as the inner diameter of the motor, the outer diameter of the motor, the air-gap length, the volume of the permanent magnet, etc. Then, simulate and analyze the output performance of the designed permanent magnet synchronous motor by means of computer finite element simulation, and analyze and verify the motor structure parameters determined by the design method, reducing the possibility that the test prototype does not meet the design requirements in terms of performance output, dynamic characteristics, working efficiency, etc., thereby reducing the design cost of the permanent magnet synchronous motor and shortening the design cycle.

[0126] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

[0127] It should be understood that, in order to streamline the present invention and assist those skilled in the art in understanding various aspects of the present invention, in the above description of the exemplary embodiments of the present invention, various features of the present invention are sometimes described in a single embodiment or with reference to a single figure. However, the present invention should not be construed as meaning that the features included in the exemplary embodiments are all essential technical features of the claims of this patent.

Claims

1. A design method for an ironless stator axial flux permanent magnet motor, characterized in that: The following steps are involved: Step 1, determining the basic structure and permanent magnet structure of the coreless stator axial flux permanent magnet motor; Step 2, determining the performance requirement parameters of the ironless stator axial flux permanent magnet motor; Step 3: Determine the stator and rotor structural parameters of the motor according to the performance requirement parameters of the motor; Step 4: Establish a simplified model of the internal magnetic circuit of the motor and determine the excitation magnetic potential of the motor; Step 5: Based on Maxwell's equations, a finite element dynamic simulation model of the coreless stator axial flux permanent magnet motor is established; Step 6: Compare the finite element dynamic simulation results with the motor performance requirement parameters. If they do not meet the requirements, modify the motor design structural parameters and electromagnetic parameters, and repeat steps 2 to 5 until the motor finite element dynamic simulation results meet the motor performance requirement parameters.

2. The design method of the coreless stator axial flux permanent magnet motor according to claim 1, characterized in that: The basic structure and permanent magnet structure of the coreless stator axial flux permanent magnet motor are determined in step 1, that is, the basic structure of the single-stator dual-rotor motor and the permanent magnet structure of the NS magnetic circuit.

3. The design method of the coreless stator axial flux permanent magnet motor according to claim 1, characterized in that: The performance requirement parameters of the ironless stator axial flux permanent magnet motor are determined as described in step 2, including the number of phases m of the ironless stator axial flux permanent magnet motor, the rated voltage U of each phase N , rated speed range and rated efficiency η. These performance parameters are determined based on the application of the motor and pre-design requirements.

4. The design method of the coreless stator axial flux permanent magnet motor according to claim 1, characterized in that: The stator and rotor structural parameters of the motor described in step 3 include the inner diameter of the motor stator, the outer diameter of the motor stator, the height of the stator teeth, the thickness of the stator disk, the air gap length, the volume of the permanent magnet, the inner diameter of the permanent magnet, the outer diameter of the permanent magnet, the number of permanent magnets per rotor, and the number of winding turns.

5. The design method of the coreless stator axial flux permanent magnet motor according to claim 4, characterized in that: According to the performance requirement parameters of the motor, the stator and rotor structural parameters of the motor are determined as follows: Step 3.1, calculate the motor outer diameter by the relationship between the motor rated power and the motor outer diameter. The calculation formula is: Among them, D out is the outer diameter of the motor, k ω is the winding coefficient; α i To calculate the pole arc coefficient, that is, to calculate the ratio of the pole arc width to the pole pitch; B δ is the maximum value of air gap flux density, η is the rated efficiency of the motor, is the power factor, A max is the electric load at the minimum radius of the motor, γ is the ratio of the inner and outer diameters of the motor, k0 is the potential coefficient, P em is the rated power of the motor; Step 3.2, according to actual needs and experience, select the appropriate ratio of the motor inner diameter to the outer diameter γ, the number of turns of each phase in series, the air gap flux density, calculate the pole arc coefficient, pole arc coefficient, motor leakage coefficient, air gap flux density distribution coefficient, and calculate the motor inner diameter D in , the calculation formula is: D in =γD out Step 3.3, select permanent magnet material, air gap length δ and motor magnetic steel thickness h M , determine the volume of the permanent magnet, the calculation formula is: Among them, V m is the volume of the permanent magnet, A m is the magnetic flux area provided by the permanent magnet, h M B is the thickness of the motor magnetic steel, δ is the air gap flux density, A δ is the effective area of ​​the air gap per pole, B m is the total magnetic flux density of the permanent magnet, δ is the air gap length, μ0 is the vacuum permeability, h M is the thickness of the motor magnetic steel, V δ is the air gap volume, E m is the magnetic energy product at the working point.

6. The design method of the coreless stator axial flux permanent magnet motor according to claim 1, characterized in that: The simplified model of the internal magnetic circuit of the motor described in step 4 is established by simplifying the internal magnetic circuit of the motor and establishing a simplified magnetic circuit model by adopting the idea of ​​field circuit without considering magnetic saturation, ignoring armature reaction and ignoring magnetic potential difference of the yoke; The above-mentioned disregarding of magnetic saturation means setting the rotor yoke on the main magnetic circuit, that is, the motor back yoke part, to be in a magnetically unsaturated state; Ignoring the armature reaction means assuming that the armature has no slots and no iron core, and when performing magnetic circuit or magnetic field analysis, the armature magnetic properties are regarded as being equal to those of air; The said neglecting of the magnetic potential difference of the yoke means setting the magnetic resistance of the rotor yoke relative to the air to be smaller than a set value, and the magnetic potential difference of the yoke is neglected.

7. The design method of the coreless stator axial flux permanent magnet motor according to claim 1, characterized in that: The simplified model of the internal magnetic circuit of the motor is established as described in step 4 to determine the excitation magnetic potential of the motor, as follows: Step 4.1: Establish a simplified magnetic circuit model of the coreless stator axial flux permanent magnet motor: Where, σ is the magnetic leakage coefficient; φ m For this reason, the total magnetic flux of the motor; φ δ A is the main magnetic flux of the magneto air gap; m is the magnetic flux area per pole corresponding to the permanent magnet; A δ is the effective area of ​​each pole air gap; B m is the total magnetic flux density of the permanent magnet; B δ is the air gap magnetic flux density; α p is the polar arc coefficient; α i is the calculation of the pole arc coefficient; p is the number of pole pairs; D in is the inner diameter; D out is the outer diameter; K F is the air gap magnetic flux distribution coefficient; Step 4.2: According to the simplified magnetic circuit model of the motor, for an axially magnetized permanent magnet motor with a coreless stator, when the permanent magnet is excited, the air gap flux density is: Among them, μ r is the relative magnetic permeability of magnetic steel, B r is the residual magnetization of the magnetic steel, K F is the air gap magnetic flux distribution coefficient, and σ is the leakage flux coefficient.

8. An ironless stator axial flux permanent magnet motor, characterized in that: The permanent magnet motor is prepared by the design method described in any one of claims 1 to 7.

Images