A method for optimizing the design of a double-rotor flux-switching motor for manned aircraft

Abstract

The application relates to a double-rotor flux switching motor optimization design method for a manned aircraft, which comprises the following steps: determining the initial size of the motor and establishing a motor electromagnetic field model to perform electromagnetic performance analysis, calculating the no-load back electromotive force and harmonic distortion rate; selecting an optimization factor and an optimization level to establish an orthogonal table, performing orthogonal test according to the orthogonal table by using the Taguchi method, selecting the optimization factor combination to optimize the no-load back electromotive force and the harmonic distortion rate, and obtaining structure parameters considering multiple targets; calculating the motor output torque ripple and establishing a permanent magnet hybrid segmented model, selecting optimization parameters to construct a response surface mathematical optimization model, and analyzing to obtain the final value of the optimization parameters. The double-rotor flux switching motor designed by the application has high torque density, high reliability and high torque overload capacity, and the rotor structure is simple, the loss is small and easy to dissipate heat, and the power-to-weight ratio of the motor of the power system of the manned aircraft is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of double-rotor flux switching motor design, and particularly relates to a double-rotor flux switching motor optimization design method for a manned aircraft. BACKGROUND

[0002] Now mainstream manned aircrafts all have problems such as low power-to-weight ratio, poor safety and poor economy, which are the main bottlenecks for the development of the manned aircrafts. As a power system motor, the double-rotor flux switching motor (DR-FSPM) has high efficiency, low torque ripple, simple rotor structure, small loss and easy heat dissipation, and is the first choice for the power system of the manned aircraft.

[0003] At present, the optimization methods for the double-rotor flux switching motor include the genetic control algorithm multi-objective optimization, the hybrid excitation switched flux permanent magnet motor with a core magnetic bridge and the flux barrier type double-rotor flux switching motor. Chen Yunyun, Quan Li, Zhu Xiaoyong, Mo Lihong and others published "Optimal Design and Electromagnetic Characteristics Analysis of Double Salient Permanent Magnet Double-Rotor Motor" in 2014, and proposed a tooth slot torque analytical model of the flux switching motor. The genetic control algorithm is used to realize the multi-objective optimization of the double-rotor permanent magnet double salient motor, and the output torque is increased by 21.05%, and the torque fluctuation is also obviously reduced. Xiang Zixuan, Quan Li, Zhu Xiaoyong, Wang Lin and others published "A Brushless Double Mechanical Port Permanent Magnet Motor for Plug-In HEVs" in 2015, and proposed a new structure of the double-rotor flux switching motor, in which a flux barrier is arranged, so that the inner and outer magnetic fields will not be coupled at the core, and the inner rotor motor and the outer rotor motor can be independently operated without affecting each other. The output torque of the motor in the full electric and hybrid electric modes is analyzed, and under the rated condition, the power factor of the outer rotor motor is 7% higher than that of the inner rotor motor. Xiaoyong Sun, Z.Q.Zhu and others published "Investigation of DC Winding Induced Voltage in Hybrid-Excited Switched-Flux Permanent Magnet Machine" in 2020, and proposed the optimization technology and various new topological structures of the flux switching motor, such as the hybrid excitation switched flux permanent magnet motor with a core magnetic bridge, and researched the application of the motor in the fields of low-cost household appliances, automobiles, wind power generation and aerospace. However, these motors do not solve the problem of the power-to-weight ratio of the motor in the power system of the manned aircraft. SUMMARY

[0004] The purpose of the present application is to provide a double-rotor flux switching motor optimization design method for manned aircraft, so that the designed double-rotor flux switching motor has high torque density, high reliability and high torque overload capacity, and the rotor structure is simple, the loss is small and easy to dissipate heat, and the power-to-weight ratio of the motor of the manned aircraft power system is improved.

[0005] The technical scheme adopted by the present application is: a double-rotor flux switching motor optimization design method for manned aircraft, comprising the following steps:

[0006] S1: selecting initial size parameters of the motor to calculate the output power P 2, power density , output torque T 2, torque density and air gap length , and using computer software to establish a two-dimensional electromagnetic field model or a three-dimensional electromagnetic field model of the motor;

[0007] S2: generating a corresponding finite element model according to the two-dimensional electromagnetic field model or the three-dimensional electromagnetic field model of the motor, and obtaining the no-load back electromotive force of the motor through finite element simulation E m , and calculating the harmonic distortion rate of the original model motor under the no-load back electromotive force E m through Fourier transform THD ;

[0008] S3: selecting the magnetization thickness of the permanent magnet h pm , the eccentricity of the inner rotor c i , the eccentricity of the outer rotor c o , the inner stator tooth arc width d i and the outer stator tooth arc width d o as optimization factors, and selecting the no-load back electromotive force fundamental wave amplitude E 1 and the harmonic distortion rate THD as optimization indexes, and selecting four optimization levels;

[0009] S4: establishing an orthogonal table according to the optimization factors and the optimization levels, performing orthogonal test according to the orthogonal table using the Taguchi method, and respectively modeling and calculating each group of experimental results using computer software according to the test results, to obtain the no-load back electromotive force fundamental wave amplitude E 1, the harmonic distortion rate THD and the output torque T 2 under rated load corresponding to each group of experimental results

[0010] S5: performing harmonic analysis by using computer software, calculating variance and average of optimization index of each optimization factor at each optimization level, analyzing the influence weight of each optimization factor through the calculation result, finding out the optimization factor with the greatest influence on the optimization index, obtaining the best optimization factor combination, and designing and optimizing the motor according to the optimization factor combination to optimize the no-load back electromotive force fundamental amplitude and harmonic distortion rate THD ;

[0011] S6: calculating motor output torque ripple; establishing a permanent magnet hybrid segmentation model, and defining tangential segmentation interval length a , radial segmentation interval length b as torque ripple optimization parameters, constructing a response surface mathematical optimization model, obtaining the response surface relationship between radial segmentation and tangential segmentation and outer rotor motor gear slot torque as a linear relationship, selecting segmentation interval values according to the linear relationship, substituting into the response point module for overall analysis, and obtaining the optimized tangential segmentation interval length a and radial segmentation interval length b .

[0012] Further, the motor initial size parameters in step S1 include rated power P N , rated speed n N , peak speed n P , motor speed n , rated torque T N , motor efficiency , input voltage U 1, input power P 1, stator tooth number P s , rotor pole number P r , motor axial effective length l a , motor leakage coefficient k d , motor wire load A S , peak value of air gap flux density B gmax , motor stator inner diameter D si , motor stator outer diameter D so , and motor stator pole arc coefficient c s .

[0013] Further, output power P 2, power density , output torqueT 2, torque density and air gap length The calculation formula is:

[0014] ;

[0015] ;

[0016] ;

[0017] ;

[0018] .

[0019] Further, the step S2 of calculating the no-load back electromotive force E m and the harmonic distortion rate thereof THD The calculation formula is as follows:

[0020] ;

[0021] ;

[0022] wherein, E 0 represents a direct current component, E i represents the amplitude of the n-th harmonic of the no-load back electromotive force, i represents the angular frequency, iw represents time, t represents the initial phase of the n-th harmonic, 1 represents the lower limit of the harmonic number for harmonic analysis, i 2 represents the upper limit of the harmonic number for harmonic analysis. n n Further, the step S6 of calculating the motor output torque ripple r The calculation formula is as follows:

[0023] K ;

[0024] wherein, max is the maximum value of the output torque,

[0025] min is the minimum value of the output torque, T avg is the average value of the output torque. T T The present application has the beneficial effects in that:

[0026]

[0027] ​​(1) The present invention uses the Taguchi method to optimize the waveform and amplitude of the no-load back electromotive force of the motor, thereby reducing the harmonic distortion rate of the no-load back electromotive force of the internal rotor motor. THD The harmonic distortion rate of the no-load back electromotive force of the external rotor motor was reduced by 63.90%. THD The amplitude of the no-load back EMF is reduced by 29.23%, making it more sinusoidal, thus improving operating efficiency and achieving the optimization target.

[0028] (2) The present invention uses the response surface methodology to optimize the torque ripple of the motor and performs finite element calculations on the motor model under rated load. The average output torque is 39.5 Nm and the torque ripple is 13.33%, which is 15.07% lower than the original model. The peak value of the cogging torque of the inner rotor motor is 0.64 Nm and the peak value of the cogging torque of the outer rotor motor is 2.04 Nm, which are 11.01% and 6.09% of the rated torque, respectively. This invention improves the torque density of the manned aircraft power system, reduces the ripple of the output torque, and achieves the optimization target requirements.

[0029] (3) By comparing the temperature rise of the motor model before and after optimization, it can be found that the optimized motor model has more stable temperature characteristics. At the same time, a qualitative comparison with the external rotor brushless DC motor shows that, under the same output torque, the armature current value of the present invention is reduced significantly, the motor copper loss is reduced, and the eddy current loss of the segmented permanent magnet is also greatly reduced, which is more economical and environmentally beneficial. Attached Figure Description

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

[0031] Figure 1 This is a flowchart of a method according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the original model of the dual-rotor flux-switching motor according to an embodiment of the present invention;

[0033] Figure 3 for Figure 2 Perform finite element analysis on the magnetic density cloud diagram under rated load conditions;

[0034] Figure 4 A comparison curve of the output torque of an internal rotor motor and a dual rotor flux-switching motor;

[0035] Figure 5The output torque comparison curve diagram of the outer rotor motor and the double rotor flux switching motor is shown in the figure;

[0036] Figure 6 The no-load back electromotive force harmonic amplitude comparison diagram of the inner rotor motor before and after optimization is shown in the figure;

[0037] Figure 7 The no-load back electromotive force harmonic amplitude comparison diagram of the outer rotor motor before and after optimization is shown in the figure;

[0038] Figure 8 The slotting torque optimization comparison curve diagram of the inner rotor motor before and after optimization is shown in the figure;

[0039] Figure 9 The slotting torque optimization comparison curve diagram of the outer rotor motor before and after optimization is shown in the figure;

[0040] Figure 10 The rated load temperature distribution diagram of the double rotor flux switching motor after optimization in the embodiment of the application is shown in the figure;

[0041] Figure 11 The stator and rotor iron loss curve diagram of the double rotor flux switching motor before optimization in the embodiment of the application is shown in the figure;

[0042] Figure 12 The stator and rotor iron loss curve diagram of the double rotor flux switching motor after optimization in the embodiment of the application is shown in the figure;

[0043] Figure 13 The permanent magnet eddy current loss curve diagram of the double rotor flux switching motor before optimization in the embodiment of the application is shown in the figure;

[0044] Figure 14 The permanent magnet eddy current loss curve diagram of the double rotor flux switching motor after optimization in the embodiment of the application is shown in the figure;

[0045] Figure 15 The winding copper loss curve diagram of the double rotor flux switching motor before optimization in the embodiment of the application is shown in the figure;

[0046] Figure 16 The winding copper loss curve diagram of the double rotor flux switching motor after optimization in the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0047] In order to enable the above-mentioned purpose, features and advantages of the present application to be more clearly understood, the present application will be further described below in conjunction with the accompanying drawings and specific embodiments. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application, however, the present application can also be implemented in other manners different from those described herein, therefore, the present application is not limited to the specific embodiments disclosed below.

[0048] The double rotor flux switching motor designed in the embodiment of the application is shown in the figure Figure 2As shown, including inner rotor 1, outer rotor 2, stator 3, S pole permanent magnet 4, N pole permanent magnet 5, A phase winding 6, B phase winding 7, C phase winding 8, etc., the permanent magnet is installed on the stator, adopts the "single magnetic field" structure, that is, the permanent magnet and the armature winding are located in the stator, the armature winding and the permanent magnet are relatively static, and the winding turns of the permanent magnet magnetic field is changed through the salient pole effect of the rotor. In the embodiment of the application, the motor adopts concentrated winding and straight slot rotor, the tooth pole matching is 12 tooth stator, 10 pole inner rotor and 22 pole outer rotor, the magnetizing thickness of the permanent magnet is selected in the optimization process h pm , inner rotor eccentricity c i , outer rotor eccentricity c o , inner stator tooth arc width d i , outer stator tooth arc width d o , tangential segmentation interval length a , radial segmentation interval length b The magnetizing thickness of the permanent magnet is optimized h pm , inner rotor eccentricity c i , outer rotor eccentricity c o , inner stator tooth arc width d i , outer stator tooth arc width d o The open circuit back electromotive force fundamental amplitude can be reduced to some extent, the sine characteristic can be improved, the operation efficiency can be improved, and the optimization target requirement can be met; the tangential segmentation interval length a , radial segmentation interval length b The torque density of the manned spacecraft power system can be improved, the output torque pulsation can be reduced, and the optimization target requirement can be met.

[0049] As Figure 1 shown, the embodiment of the application provides a double-rotor magnetic flux switching motor optimization design method for a manned spacecraft, which comprises the following steps:

[0050] S1: selecting motor initial size parameters to calculate output power P 2, power density , output torque T 2, torque density and air gap length , and using computer software to establish a two-dimensional electromagnetic field model or a three-dimensional electromagnetic field model of the motor.

[0051] In the embodiment of the application, the motor initial size parameters include rated powerP N rated speed n N peak speed n P motor speed n rated torque T N motor efficiency input voltage U 1, input power P 1, stator tooth number P s rotor pole number P r motor axial effective length l a motor leakage coefficient k d motor wire load A S peak value of air gap magnetic flux density B gmax motor stator inner diameter D si motor stator outer diameter D so and motor stator pole arc coefficient c s .

[0052] output power P 2, power density output torque T 2, torque density and air gap length The calculation formula is:

[0053] ;

[0054] ;

[0055] ;

[0056] ;

[0057] .

[0058] S2: generate the corresponding finite element model according to the two-dimensional electromagnetic field model or the three-dimensional electromagnetic field model of the motor, and obtain the no-load back electromotive force of the motor through finite element simulation E m , and calculate the harmonic distortion rate of the original model motor under the no-load back electromotive force E m . THD .

[0059] the no-load back electromotive force E m harmonic distortion rate THD The calculation formula is as follows:

[0060] ;

[0061] ;

[0062] wherein, E 0 represents a direct current component, E i represents the amplitude of the n-th harmonic of the no-load back electromotive force, i represents an angular frequency, iw represents time, t represents the initial phase of the n-th harmonic, 1 represents a lower limit value of the harmonic number for harmonic analysis, i 2 represents an upper limit value of the harmonic number for harmonic analysis. In the embodiment of the present application, the proportion of odd harmonics is relatively large through finite element analysis, so 3-18 harmonics are selected for distortion rate calculation, that is, n 1 is 3, n 2 is 18, then the formula of the harmonic distortion rate can be expressed as: n . n In the embodiment of the present application, the computer software used includes Auto CAD, Solidworks, Pro / E, MATLAB, Maxwell and workbench, etc. When constructing a two-dimensional electromagnetic field model or a three-dimensional electromagnetic field model of the motor, instead of calling an existing model in Maxwell's RMxport, a two-dimensional model or a three-dimensional model of the motor needs to be drawn by drawing software such as Auto CAD, Solidworks or Pro / E, a file in a specific format is generated and imported into Maxwell for Boolean operation to obtain a motor finite element model. In the embodiment of the present application, an Auto CAD is used to design a two-dimensional motor model, after the two-dimensional motor model is imported into Maxwell, material properties are defined, finite element analysis boundaries are set, excitation is set, mesh division is performed, Band domain design is performed and other model pre-processing, the stator and rotor core materials are DW310-35 silicon steel sheets, the air gap is vacuum, the permanent magnet is a neodymium iron boron magnet NdFe35 with a maximum magnetic energy product of 35, and the winding material is copper, so as to obtain an original model of the motor as shown in

[0063] Figure 2

[0064] ​​​When meshing a finite element model, the meshing accuracy varies in different regions; higher meshing accuracy results in longer computation time. When analyzing the core saturation of a motor, the magnetization curve of the core material, i.e., the BH curve, needs to be referenced. In this embodiment of the invention, the magnetic flux density map analyzed under rated load conditions for the finite element model is shown below. Figure 3 As shown, by Figure 3 It can be seen that when the magnetic flux of the internal rotor motor and the external rotor motor is at its maximum, there is an unavoidable slight saturation in the stator and rotor teeth. This is due to the magnetic focusing effect and working principle of the flux switching motor. It can be improved to a certain extent without affecting the motor performance.

[0065] To apply the dual-rotor flux-switching motor in manned spacecraft, it is necessary to balance output torque with low torque ripple. To verify that the coupling of the inner and outer rotor motor fluxes can improve the overall output torque of the motor, the inner and outer rotor motors were modeled and analyzed separately to obtain their respective output torques. These torques were then compared with the output torque of the dual-rotor flux-switching motor before optimization, yielding the following results: Figure 4 and Figure 5 The results are shown. The modeling dimensional parameters of the inner rotor motor and the outer rotor motor are required to be consistent with those of the original dual-rotor flux-switching motor. Finite element analysis was used to compare the output torque of both motors with that of the original dual-rotor flux-switching motor. Under the same volume and power conditions, the output torque of both the optimized inner rotor motor and the outer rotor motor in the dual-rotor flux-switching motor is improved compared to the original motor, especially the output torque of the outer rotor motor. Furthermore, the resulting torque ripple can be reduced through parameter optimization, resulting in a more stable motor output torque.

[0066] S3: Select the magnetization thickness of the permanent magnet h pm 1. Inner rotor eccentricity c i External rotor eccentricity c o Inner stator tooth arc width d i and the outer stator tooth arc width d o As an optimization factor, the fundamental amplitude of the motor's no-load back EMF was selected. E 1 and its harmonic distortion rate THD Four optimization levels were selected as optimization indicators.

[0067] S4: Establish an orthogonal array based on the optimization factor and optimization level, and conduct orthogonal experiments according to the Taguchi method. Based on the experimental results, use computer software to model and calculate the fundamental amplitude of the no-load back EMF corresponding to each experimental result. E 1. Harmonic distortion rateTHD and output torque under rated load T 2. In this embodiment of the invention, the orthogonal array contains 16 sets of orthogonal experiments.

[0068] S5: Use computer software to perform harmonic analysis, calculate the variance and average value of the optimization index of each optimization factor at each optimization level, analyze the influence weight of each optimization factor through the calculation results, find the optimization factor with the greatest influence on the optimization index, obtain the best combination of optimization factors, and optimize the design of the motor according to the combination of optimization factors, optimize the amplitude of the no-load back EMF fundamental wave and the harmonic distortion rate, and obtain structural parameters that take into account multiple objectives.

[0069] like Figure 6 and Figure 7 As shown, after obtaining the no-load back electromotive force of the inner rotor motor and the outer rotor motor through finite element calculation, the waveforms are processed by fast Fourier transform. In this embodiment of the invention, MATLAB is used to calculate the corresponding harmonic distortion rate. THD The waveform distortion rates of the inner rotor motor and outer rotor motor in the original model were found to be 4.10% and 0.65%, respectively, indicating that the content of odd harmonics was significantly higher than that of even harmonics. Considering the application background of autonomous manned aircraft, appropriate optimization objectives were formulated. Sixteen five-factor, four-level orthogonal experiments were conducted using rotor tooth arc eccentricity, and the standard mean and variance were calculated to determine the weights of the optimization factors.

[0070] By combining weights for optimization, the following motor design parameters can be obtained: thickness in the magnetization direction of the permanent magnet. h pm =1.8mm, outer rotor eccentricity c o = 67mm, inner rotor eccentricity c i = 21mm, inner stator tooth arc width d o = 6°, inner stator tooth arc width d i = 7°. Modeling this parameter combination and importing it into Maxwell yields the no-load back EMF, waveform distortion rate, and output torque before and after optimization, as shown in Table 1.

[0071] Table 1 Performance Comparison Before and After Optimization

[0072]

[0073] Through optimization, the harmonic distortion rate of the inner rotor motor of the dual-rotor flux-switching motor is reduced. THD The harmonic distortion rate of the external rotor motor was reduced by 63.90%. THD The amplitude of the no-load back EMF was reduced by 29.23%.E 1There is a certain cut, and the optimization target is consistent. The base wave amplitude of the no-load back electromotive force before and after optimization E 1Harmonic distortion rate THD Comparison shows that the target requirement of the Taguchi method optimization is achieved.

[0074] S6: Calculate the motor output torque ripple , wherein, K r is the torque ripple, T max is the maximum value of the output torque, T min is the minimum value of the output torque, T avg is the average value of the output torque; a hybrid segmented model of permanent magnets is established, and the tangential segmentation interval length a , the radial segmentation interval length b is the torque ripple optimization parameter, a response surface mathematical optimization model is constructed, and the response surface relationship between the radial segmentation and the tangential segmentation and the cogging torque of the external rotor motor is linear. According to the linear relationship, the segmentation interval value is selected, substituted into the response point module for overall analysis, and the optimized tangential segmentation interval length a and the radial segmentation interval length b are obtained.

[0075] The finite element calculation result is brought into the torque ripple calculation formula , and the model torque ripple after Taguchi optimization is 15.70%. The mesh division of the air gap is set to 0.15mm in the pre-processing of the cogging torque calculation model, which is divided into four layers. The inner and outer rotor speeds are set to 1 degree per second. The influence of the hybrid segmentation of permanent magnets on the motor cogging torque is analyzed by using Workbench and Maxwell joint simulation. On the basis of the no-load back electromotive force optimization, the hybrid segmentation model of permanent magnets is established, and the.aedt file is generated as the model imported into Workbench. The model is imported into Workbench software, the file generated in the previous step is selected, and the response surface method is used for optimization. Sampling is carried out within the value range of the optimization variable. The Latin hypercube sampling method is used in the embodiment of the application, and a total of 9 groups of sampling experiments are designed, and the calculation is updated as the corresponding surface construction data. After obtaining the experimental data, the response surface is constructed, the Kriging unbiased estimation model is selected, and the automatic point adding is selected to accurately predict the unknown experimental data points from the known experimental data points. On the basis of the above candidate points, the response point module is brought into the overall analysis, and the final value is obtained: the tangential segmentation interval length a is-0.05mm, and the radial segmentation interval length bis 0 mm. The final value is brought back to the Maxwell module for finite element calculation to verify the correctness of the response surface mathematical model, and the final slotting torques of the inner rotor motor and the outer rotor motor before and after optimization are obtained as shown in Figure 8 and Figure 9 It can be seen that the maximum slotting torques of the inner rotor motor and the outer rotor motor are reduced by 18.68% and 19.42% respectively. The finite element calculation is performed on the motor model after optimization under the rated load, and the average output torque is 39.5 Nm, and the torque ripple is 13.33%, which is reduced by 15.07% compared with the original model. The peak slotting torques of the inner rotor motor and the outer rotor motor are 0.64 Nm and 2.04 Nm, which are 11.01% and 6.09% of the rated torque respectively.

[0076] The loss is introduced into the thermal analysis module, the current environmental temperature is set to 22℃, and the simulation time is 24000s. The iterative calculation is performed to obtain the temperature distribution of the double-rotor flux switching motor under the rated load, and the temperature distribution diagram is shown in Figure 10 It can be seen from Figure 10 that when the heat transfer between the motor and the environment reaches stability, the highest temperature in the motor appears on the outer rotor armature winding, which reaches 127.06℃, which is about the level of winding B class insulation, and the temperatures of the inner and outer windings are obviously higher than those of other components. When the motor runs under the rated load, the outer rotor motor armature winding passes through a large current to generate a large copper loss, which has a very high temperature. The armature winding in the stator slot is surrounded by an insulating material with poor heat conduction performance. The heat of the inner and outer armature windings is transmitted through the stator. At the same time, the eddy current loss generated by the permanent magnet is also transmitted through the stator. The stator core is cooled through the liquid cooling channel, so the temperature is relatively low. The heat of the stator core and the permanent magnet is partially transmitted to the inner rotor and the outer rotor through the air gap with low thermal conductivity, causing a certain temperature rise. The inner rotor and the shaft with good heat conduction performance are directly in contact for heat dissipation. The outer rotor is directly in contact with the housing, and the housing is directly in contact with the air for heat dissipation. Finally, the temperature of the inner rotor is higher than that of the outer rotor.

[0077] At the same output torque, due to the magnetic aggregation effect, only a small current is needed to achieve a large output torque. For the same output torque of 40 Nm, the power of the outer rotor brushless DC motor U15XL of T-MOTOR company reaches 13 kW, and the armature current is 132.6 A. For the double-rotor flux switching motor described in the embodiment of the present application, only 6.3 kW is needed, and the armature current is 47.4 A. Under the condition of the same volume, the high magnetic flux density in the double-rotor flux switching motor reduces the main loss of the motor, i.e. the copper loss. The amount of permanent magnet used by the double-rotor flux switching motor is much smaller than that of the outer rotor brushless DC motor U15XL. After the permanent magnet is segmented, the eddy current loss of the permanent magnet is greatly reduced. The temperature rise of the motor is greatly reduced, and the motor has the ability to operate stably, thereby improving the economic and environmental benefits.

[0078] The rotor iron loss curve chart, the permanent magnet eddy current loss curve chart and the winding copper loss curve chart of the double-rotor flux switching motor in the embodiments of the present application before and after optimization are shown in FIGS. 1-3. Figures 11-16 As can be seen from FIGS. 1-3, the armature winding copper loss is the main component of the motor loss, and the comparison of the losses before and after optimization shows that the rotor iron loss is reduced by 12.64 W, the permanent magnet eddy current loss is reduced by 81.68 W due to the mixed segmentation, and the winding copper loss changes little. Figures 11-16

[0079] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Various modifications and changes can be made by those skilled in the art based on the principles and spirit of the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for the optimal design of a dual-rotor flux-switching electric machine for manned aircraft, characterized by, comprising the steps of: S1: select motor initial size parameter to calculate output power P 2, power density , output torque T 2, torque density And air gap length And use computer software to establish two-dimensional electromagnetic field model or three-dimensional electromagnetic field model of motor; S2: generate a corresponding finite element model according to the two-dimensional electromagnetic field model or the three-dimensional electromagnetic field model of the motor, and obtain the no-load back electromotive force of the motor through finite element simulation E m , and the harmonic distortion rate of the original model motor under the no-load back electromotive force E m THD is calculated by Fourier transform​ S3: Select the magnetization thickness of permanent magnet h pm , inner rotor eccentricity c i , outer rotor eccentricity c o , inner stator tooth arc width d i and outer stator tooth arc width d o As an optimization factor, select the base value of the no-load back electromotive force amplitude of the motor E 1 and its harmonic distortion rate THD As an optimization index, select four optimization levels; S4: According to the optimization factor and the optimization level, an orthogonal table is established, orthogonal test is carried out according to the orthogonal table using the Taguchi method, and modeling calculation is carried out on each group of experimental results by using computer software according to the test results, so as to obtain the no-load back electromotive force fundamental wave amplitude corresponding to each group of experimental results E 1, harmonic distortion rate THD and output torque under rated load T 2; S5: using computer software to perform harmonic analysis, calculating the optimization index variance and optimization index average value of each optimization factor at each optimization level, analyzing the influence weight of each optimization factor through the calculation result, finding out the optimization factor with the greatest influence on the optimization index, obtaining the best optimization factor combination, and designing and optimizing the motor according to the optimization factor combination to optimize the no-load back electromotive force fundamental wave amplitude and harmonic distortion rate THD ; S6: calculating the motor output torque ripple; Establish a hybrid segmented model of permanent magnets and define the tangential segment interval length. a Radial segment interval length b To optimize torque ripple parameters, a response surface mathematical optimization model is constructed. The linear relationship between the radial and tangential segments and the cogging torque of the external rotor motor is obtained. Based on this linear relationship, the segment interval value is selected and substituted into the response point module for overall analysis to obtain the optimized tangential segment interval length. a and radial segment interval length b .

2. The method for optimal design of a dual-rotor flux-switching motor for manned aerial vehicles according to claim 1, characterized in that, The initial dimension parameters of the motor in step S1 include rated power P N , rated rotating speed n N , peak rotating speed n P , motor rotating speed n , rated torque T N , motor efficiency , input voltage U 1, input power P 1, number of stator teeth P s , number of rotor poles P r , effective length of motor axial direction l a , leakage coefficient of motor k d , wire load of motor A S , peak value of air gap magnetic flux density B gmax , inner diameter of motor stator D si , outer diameter of motor stator D so , pole arc coefficient of motor stator c s .

3. The method for the optimal design of a dual-rotor flux-switching motor for manned aerial vehicles according to claim 2, characterized in that, Output power P 2, power density , output torque T 2, torque density and air gap length The calculation formula is: ； ； ； ； 。 4. The method for optimal design of a dual-rotor flux-switching motor for manned aerial vehicles according to claim 3, wherein, The step S2 of calculating the no-load back EMF E m and the harmonic distortion rate thereof THD The calculation formula is as follows: ； ； wherein E 0 represents a direct current component, E i represents a no-load back electromotive force i harmonic amplitude, iw represents an angular frequency, t represents time, represents an initial phase of i a harmonic, n 1 represents a lower limit value of a harmonic number for harmonic analysis, n 2 represents an upper limit value of a harmonic number for harmonic analysis.

5. The method for the optimal design of a dual-rotor flux-switching motor for manned aerial vehicles according to claim 4, characterized in that, The motor output torque ripple in the step S6 K r The calculation formula is as follows: ； wherein, T max Tmax is the maximum value of the output torque, T min Tmin is the minimum value of the output torque, T avg Tave is the average value of the output torque.

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