Motor design method and device based on decoupling cross-fusion magnetic circuit

Abstract

The application discloses a motor design method based on decoupling cross fusion magnetic circuit, and the method comprises the following steps: splitting the stator d-axis magnetic motive force into size pole magnetic motive force distribution data and the rotor permanent magnet magnetic motive force into permanent magnet characteristic position magnetic motive force distribution data by asymmetric distribution of windings; respectively establishing a stator side size pole magnetic circuit model and a rotor side permanent magnet characteristic position magnetic circuit model; identifying the common reluctance region of the two models and obtaining the common reluctance data after freezing by using the key magnetic conductivity freezing method; correcting the parameters of the permanent magnet characteristic position magnetic circuit model based on the data; and finally, iteratively solving the size pole magnetic circuit model and the corrected permanent magnet characteristic position magnetic circuit model until the magnetic flux density error is less than a preset threshold value, so that the motor d-axis inductance calculated by the self-consistent magnetic flux distribution data is more accurate, thereby significantly improving the calculation accuracy of the d-axis-permanent magnet cross coupling magnetic field without increasing the finite element level calculation burden.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor body design, and particularly relates to a motor design method and device based on decoupling cross-fusion magnetic circuit, an electronic device and a computer readable storage medium. BACKGROUND

[0002] In a permanent magnet motor, the permanent magnet flux and the d-axis flux are interlinked. Based on the proposed unequal-width magnetic circuit model, the d-axis magnetic motive force is asymmetrically distributed, and the magnetic resistance characteristic in the d-axis magnetic circuit is "large and small pole" distribution. The size of the permanent magnet magnetic motive force is several times that of the stator magnetic motive force, so when the magnetic flux generated by the different excitation sources of the permanent magnet, the stator d-axis and the q-axis shares the same magnetic resistance, the dominant one is the permanent magnet flux.

[0003] The current numerical calculation method of the permanent magnet motor is relatively mature, including analytical method and finite element method. However, the existing analytical method and finite element method have certain problems. The analytical method usually only considers local saturation and is difficult to consider the cross-coupling effect. Although the finite element method has high accuracy, it is time-consuming and requires a large amount of computer hardware. Especially for megawatt direct-drive wind turbines and other low-speed large-capacity permanent magnet motors, due to the high design of electromagnetic load, the influence of saturation and cross-coupling is more significant, and the existing method is difficult to meet the calculation requirements.

[0004] The root cause of this problem is that, on the one hand, the stator d-axis magnetic motive force has a "large and small pole" trend due to the asymmetric distribution of the winding, while the rotor side permanent magnet magnetic motive force is uniformly distributed. On the other hand, for each excitation source (stator d-axis and permanent magnet), the most accurate magnetic circuit model to describe its flux behavior is different. On the other hand, when two excitation sources share the same magnetic circuit, the characteristics of one excitation source cannot be accurately described by the magnetic circuit, especially at key positions such as adjacent magnetic circuit connections. On the other hand, the permanent magnet magnetic motive force is much larger than the stator magnetic motive force, and the influence of the permanent magnet on saturation needs to be considered when calculating the magnetic resistance in the key area. SUMMARY

[0005] In order to overcome the defects of the prior art, the embodiments of the present application provide a motor design method and device based on decoupling cross-fusion magnetic circuit, which considers the accurate description of each magnetic motive force in its magnetic circuit, maximizes the characteristics of each magnetic motive force in its magnetic circuit, and then iteratively calculates the magnetic circuit, realizes the improvement of the magnetic field calculation accuracy, and gives it sufficient engineering application value.

[0006] On the one hand, the embodiments of the present application propose a motor design method based on decoupling cross-fusion magnetic circuit, comprising:

[0007] Splitting the stator d-axis magnetomotive force into size pole magnetomotive force distribution data according to asymmetric distribution of windings, and splitting the rotor permanent magnet magnetomotive force into permanent magnet characteristic position magnetomotive force distribution data according to uniform distribution;

[0008] Establishing a stator side size pole magnetic circuit model according to the size pole magnetomotive force distribution data, and establishing a rotor side permanent magnet characteristic position magnetic circuit model according to the permanent magnet characteristic position magnetomotive force distribution data;

[0009] Identifying a shared reluctance region between the size pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model, and using a key permeability freezing method in the shared reluctance region to obtain frozen shared reluctance data;

[0010] Based on the frozen shared reluctance data, performing parameter correction on the permanent magnet characteristic position magnetic circuit model to obtain a corrected permanent magnet characteristic position magnetic circuit model;

[0011] Linking the size pole magnetic circuit model and the corrected permanent magnet characteristic position magnetic circuit model, and through iterative calculation, making the magnetic flux density error less than a preset threshold to obtain self-consistent magnetic flux distribution data, and calculating motor d-axis inductance according to the self-consistent magnetic flux distribution data to obtain motor design parameters.

[0012] Further, the key permeability freezing method is used in the shared reluctance region to obtain frozen shared reluctance data, including:

[0013] The permeability obtained by calculating the permanent magnet magnetic circuit is frozen and assigned to the shared reluctance region to obtain frozen shared reluctance data.

[0014] Further, the parameter correction on the permanent magnet characteristic position magnetic circuit model based on the frozen shared reluctance data to obtain the corrected permanent magnet characteristic position magnetic circuit model includes:

[0015] Based on the frozen shared reluctance data, introducing a linear weakening amount of stator d-axis magnetomotive force to permanent magnet magnetomotive force in the permanent magnet characteristic position magnetic circuit model, the linear weakening amount being a vector sum of magnetomotive forces of each tooth relative to the permanent magnet, to obtain corrected permanent magnet magnetomotive force data;

[0016] Substituting the corrected permanent magnet magnetomotive force data back into the permanent magnet characteristic position magnetic circuit model to obtain the corrected permanent magnet characteristic position magnetic circuit model.

[0017] Further, the key permeability freezing method only freezes the magnetic pole upper triangular region and the rotor yoke reluctance, and the frozen permeability value is taken from the converged permeability of the region under the excitation of the permanent magnet alone.

[0018] Further, the linear weakening amount acquisition manner comprises: firstly extracting d-axis tooth magnetic motive force of a preset number of teeth aligned with the center line of the permanent magnet by the size pole method, and then summing the preset number of tooth magnetic motive force vectors and multiplying by a position proportion correction coefficient to obtain the weakening amount.

[0019] Further, the position proportion correction coefficient is obtained by projecting the center line of the permanent magnet onto the stator tooth, and calculating a proportional linear interpolation of the permanent magnet covered tooth width and the whole tooth width.

[0020] Further, the size pole magnetic motive force distribution data is obtained by superimposing magnetic motive force harmonic components caused by each pole and each phase slot number asymmetry, and the permanent magnet feature position magnetic motive force distribution data is obtained by averaging the magnetic motive force of 4-tooth or 5-tooth feature positions after uniformly dividing the permanent magnet in the circumferential direction.

[0021] On the other hand, the embodiment of the present application also proposes a motor design device based on decoupling cross-fusion magnetic circuit, comprising: a data acquisition module, configured to split the stator d-axis magnetic motive force into size pole magnetic motive force distribution data according to winding asymmetry distribution, and split the rotor permanent magnet magnetic motive force into permanent magnet feature position magnetic motive force distribution data according to uniform distribution;

[0022] a magnetic circuit model construction module, configured to establish a stator side size pole magnetic circuit model according to the size pole magnetic motive force distribution data, and establish a rotor side permanent magnet feature position magnetic circuit model according to the permanent magnet feature position magnetic motive force distribution data;

[0023] a data processing module, configured to identify a common magnetic resistance region between the size pole magnetic circuit model and the permanent magnet feature position magnetic circuit model, and obtain frozen common magnetic resistance data in the common magnetic resistance region by using a key magnetic permeability freezing method;

[0024] a correction module, configured to perform parameter correction on the permanent magnet feature position magnetic circuit model based on the frozen common magnetic resistance data to obtain a corrected permanent magnet feature position magnetic circuit model;

[0025] a parameter calculation module, configured to solve the size pole magnetic circuit model and the corrected permanent magnet feature position magnetic circuit model, and obtain self-consistent magnetic flux distribution data by iterative calculation with a magnetic flux density error less than a preset threshold, and calculate motor d-axis inductance according to the self-consistent magnetic flux distribution data to obtain motor design parameters.

[0026] In another aspect, the embodiment of the present application also proposes an electronic device, comprising: a memory and one or more processors connected to the memory, the memory stores a computer program, and the processor is used to execute the computer program to realize the motor design method based on decoupling cross-fusion magnetic circuit as described in any one of the above embodiments.

[0027] In yet another aspect, an embodiment of the present application also provides a computer readable storage medium storing computer executable instructions for performing the motor design method based on decoupled cross-fusion magnetic circuit as described in any one of the above embodiments.

[0028] From the above, the above embodiments of the present application can have at least one or more of the following beneficial effects compared with the prior art:

[0029] The present application provides a motor design method based on decoupled cross-fusion magnetic circuit, by splitting the stator d-axis magnetic motive force into "large and small pole" magnetic motive force distribution data according to asymmetric winding distribution, splitting the rotor permanent magnet magnetic motive force into permanent magnet characteristic position magnetic motive force distribution data according to uniform distribution, respectively establishing stator side "large and small pole" magnetic circuit model and rotor side permanent magnet characteristic position magnetic circuit model, identifying the common reluctance region of the two sets of models and obtaining the frozen common reluctance data by using the key magnetic permeability freezing method, then based on the data, the permanent magnet characteristic position magnetic circuit model is parameter corrected, finally the "large and small pole" magnetic circuit model and the corrected permanent magnet characteristic position magnetic circuit model are iterated until the magnetic flux density error is less than the preset threshold, the d-axis inductance of the motor calculated from the self-consistent magnetic flux distribution data is more accurate, thereby significantly improving the calculation accuracy of the d-axis-permanent magnet cross-coupling magnetic field without increasing the finite element level calculation burden. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0031] Figure 1 A flowchart of a motor design method based on decoupled cross-fusion magnetic circuit provided by an embodiment of the present application is shown in the figure;

[0032] Figure 2 A linear correction example of permanent magnet magnetic motive force source provided by an embodiment of the present application is shown in the figure;

[0033] Figure 3 A magnetic circuit model schematic diagram of permanent magnet magnetic circuit 5 tooth characteristic position provided by an embodiment of the present application is shown in the figure;

[0034] Figure 4 A magnetic circuit model schematic diagram of permanent magnet magnetic circuit 4 tooth characteristic position provided by an embodiment of the present application is shown in the figure;

[0035] Figure 5 An equivalent magnetic circuit schematic diagram of permanent magnet magnetic circuit 5 tooth characteristic position provided by an embodiment of the present application is shown in the figure;

[0036] Figure 6The equivalent magnetic circuit schematic diagram of the permanent magnet magnetic circuit 4-tooth characteristic position provided for the embodiment of the present application is shown in the figure;

[0037] Figure 7 The linear correction example diagram of the permanent magnet magnetic motive force source provided for the embodiment of the present application is shown in the figure;

[0038] Figure 8 The flow schematic diagram of the magnetic circuit iterative calculation provided for the embodiment of the present application is shown in the figure;

[0039] Figure 9 The magnetic permeability variation curve schematic diagram of the silicon steel sheet used in the present example provided for the embodiment of the present application is shown in the figure;

[0040] Figure 10 The structural schematic diagram of the motor design device based on the decoupling cross-fusion magnetic circuit provided for the embodiment of the present application is shown in the figure;

[0041] Figure 11 The structural schematic diagram of an electronic device provided for the embodiment of the present application is shown in the figure;

[0042] Figure 12 The structural schematic diagram of a computer readable storage medium provided for the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0043] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described below with reference to the accompanying drawings and in combination with the embodiments.

[0044] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all the embodiments of the present application, which should all belong to the protection scope of the present application.

[0045] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are applicable to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the terms thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0046] It should be further explained that the division of the multiple embodiments in the present application is only for the convenience of description, and should not constitute a special limitation. The features in the various embodiments can be combined with each other without contradiction, and are mutually referenced.

[0047] In the permanent magnet motor, the permanent magnet flux and the d-axis flux are cross-linked. Based on the proposed unequal-width magnetic path model, the d-axis magnetic motive force is asymmetrically distributed, and the magnetic resistance characteristic in the d-axis magnetic path is "large and small pole" distribution. The size of the permanent magnet magnetic motive force is several times that of the stator magnetic motive force, so when the magnetic flux generated by the different excitation sources of the permanent magnet, the stator d-axis and the q-axis shares the same magnetic resistance, the dominant one is the permanent magnet flux.

[0048] The normalization method can provide a simple and convenient solution to the cross-coupling between the d-axis magnetic path and the permanent magnet magnetic path. However, it needs to be considered that the stator d-axis magnetic motive force has a "large and small pole" trend due to the asymmetric distribution of the winding. The magnetic path that most accurately describes the magnetic flux distribution under the joint action of its asymmetric magnetic motive force and magnetic resistance is the "large and small pole" magnetic path. The rotor side excitation source is the permanent magnet with uniform magnetic motive force and distribution. The magnetic path that most accurately describes its magnetic flux behavior is the permanent magnet characteristic position magnetic path. This means that for each excitation source, the most accurate magnetic path for them is determined according to their respective excitation source characteristics. Therefore, the magnetic path division can accurately reflect the behavior of the magnetic flux in the magnetic path.

[0049] However, when two excitation sources share the same magnetic path, one of the excitation sources cannot be accurately described by the magnetic path. For example, the key positions such as adjacent magnetic path connections are easy to overlook when taking other magnetic paths. This further leads to errors. Therefore, the present application proposes a motor design method based on decoupling cross-fusion magnetic path, which tries to accurately describe the magnetic path of each magnetic motive force as much as possible, and maximizes the characteristics of the magnetic path of each magnetic motive force, and then iteratively calculates the magnetic path.

[0050] According to an aspect of an embodiment of the present application, a motor design method based on decoupling cross-fusion magnetic path is provided. The motor design method based on decoupling cross-fusion magnetic path provided by the embodiment of the present application, for example, includes: Figure 1 The motor design method based on decoupling cross-fusion magnetic path provided by the embodiment of the present application is described, for example, including:

[0051] Step S1, the stator d-axis magnetomotive force is split into size pole magnetomotive force distribution data according to asymmetric distribution of windings, and the rotor permanent magnet magnetomotive force is split into permanent magnet characteristic position magnetomotive force distribution data according to uniform distribution; Step S2, a stator side size pole magnetic circuit model is established according to the size pole magnetomotive force distribution data, and a rotor side permanent magnet characteristic position magnetic circuit model is established according to the permanent magnet characteristic position magnetomotive force distribution data; Step S3, a common magnetic reluctance region between the size pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model is identified, and a key magnetic permeability freezing method is used in the common magnetic reluctance region to obtain frozen common magnetic reluctance data; Step S4, the permanent magnet characteristic position magnetic circuit model is corrected based on the frozen common magnetic reluctance data to obtain a corrected permanent magnet characteristic position magnetic circuit model; Step S5, the size pole magnetic circuit model and the corrected permanent magnet characteristic position magnetic circuit model are solved, the magnetic flux density error is less than a preset threshold through iterative calculation, self-consistent magnetic flux distribution data are obtained, and motor d-axis inductance is calculated according to the self-consistent magnetic flux distribution data to obtain motor design parameters.

[0052] In the embodiment, first, the stator d-axis magnetomotive force is split into size pole magnetomotive force distribution data according to asymmetric distribution of windings, and the rotor permanent magnet magnetomotive force is split into permanent magnet characteristic position magnetomotive force distribution data according to uniform distribution to obtain independent magnetomotive force source data of the two excitation sources respectively.

[0053] Further, a stator side size pole magnetic circuit model is established according to the size pole magnetomotive force distribution data, and a rotor side permanent magnet characteristic position magnetic circuit model is established according to the permanent magnet characteristic position magnetomotive force distribution data to obtain independent magnetic circuit models corresponding to the two excitation sources respectively.

[0054] Then, a common magnetic reluctance region between the size pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model is identified, and a key magnetic permeability freezing method is used in the common magnetic reluctance region to obtain frozen common magnetic reluctance data.

[0055] Specifically, since the permanent magnet magnetomotive force is much larger than the stator magnetomotive force, when the motor contains both the permanent magnet magnetomotive force and the stator current excitation source, the permanent magnet magnetomotive force plays a dominant role. Then in the magnetic circuit, the magnetic reluctance of the key part, including the triangular area above the magnetic pole and the rotor yoke, their saturation is mainly caused by the magnetic flux generated by the permanent magnet excitation. Therefore, in the calculation of the magnetic reluctance of the key region, the application focuses on the influence of the permanent magnet on the saturation, and when the key magnetic permeability is frozen, the permanent magnet magnetic circuit is used to freeze the magnetic permeability of part of the magnetic reluctance in the d-axis size pole magnetic circuit.

[0056] Further, based on the common frozen reluctance data, the linear weakening amount of the stator d-axis magnetomotive force to the permanent magnet magnetomotive force is introduced into the magnetic circuit model of the characteristic position of the permanent magnet, to obtain the corrected permanent magnet magnetomotive force data; wherein the linear weakening amount is set as the vector sum of the magnetomotive force of each tooth relative to the permanent magnet.

[0057] Specifically, the influence of the stator magnetomotive force on the permanent magnet magnetic circuit is considered. In the stator size pole magnetic circuit, the excitation source is the winding, and the excitation of the winding changes with the coil current. However, in the characteristic position magnetic circuit of the permanent magnet, the excitation source is only the permanent magnet. Its magnetomotive force is given, and when there is only a single magnetomotive force source of the permanent magnet in the magnetic circuit, it is difficult to reflect its change with the stator current. Therefore, the actual situation is simulated, the direction of the permanent magnet magnetomotive force is opposite to that of the stator d-axis magnetomotive force, and the d-axis current has a weakening effect on the permanent magnet magnetomotive force during the operation of the motor.

[0058] In view of this actual situation, referring to the research method of the double reaction theory of the salient pole synchronous motor, the d-axis magnetomotive force is linearly weakened to the permanent magnet magnetomotive force. The size of the weakening amount is set as the vector sum of the magnetomotive force of each tooth relative to the permanent magnet. In the characteristic magnetic circuit of the permanent magnet, the permanent magnet magnetomotive force source is linearly corrected to correspond to the , for example, as shown in Figure 2 .

[0059] According to the size pole method, the following can be obtained: , , , , Here, the weakening amount is defined as the vector sum of the magnetomotive force of each tooth relative to the permanent magnet.

[0060] (1)

[0061] wherein, is the correction coefficient when the common tooth magnetomotive force is used, and in the corresponding position of the example, and need to be corrected according to the position ratio of the tooth relative to the permanent magnet, as shown by the blue line in Figure 2 , the correction coefficient can be obtained, which is substituted into equation (1) to obtain .

[0062] The d-axis tooth magnetomotive force of the four positions can be obtained by the size pole method, and the specific corrected permanent magnet magnetomotive force can be calculated as follows:

[0063] (2)

[0064] (3)

[0065] (4)

[0066] (5)

[0067] Finally, the size of the magnetic circuit model is combined with the corrected permanent magnet characteristic position magnetic circuit model, the magnetic flux density error is less than the preset threshold through iterative calculation, the self-consistent magnetic flux distribution data is obtained, and the motor d-axis inductance is calculated according to the self-consistent magnetic flux distribution data, and the motor design parameters are obtained.

[0068] Next, a specific embodiment of the motor design method based on decoupling cross-fusion magnetic circuit is described.

[0069] In a 360-slot 84-pole permanent magnet motor, for example, due to the non-integer number of slots per pole per phase, the stator winding is obviously asymmetrically distributed in space, resulting in a periodic "large and small pole" waveform of the d-axis magnetic motive force along the circumferential direction. This waveform can be decomposed by Fourier to obtain the fundamental wave and a series of harmonic components, where the fundamental wave has the highest amplitude, and the harmonic components are used to finely depict local concave and convex; After accumulating these discrete slot magnetic motive forces by angle, the "large and small pole" magnetic motive force distribution data can be obtained, which is stored in 1° steps within 360° mechanical angle, a total of 360 data points, directly reflecting the spatial non-uniformity of the stator side excitation source.

[0070] Taking a 360-slot 84-pole permanent magnet motor as an example, the permanent magnet magnetic circuit has two different characteristic positions: 4-tooth characteristic position and 5-tooth characteristic position. These two characteristic positions contain the same number of teeth as the q-axis, and their magnetic circuit model and equivalent magnetic circuit diagram are shown in Figures 3-6 respectively. Among them, , is the air magnetic barrier reluctance, is the tooth leakage reluctance, is the stator yoke reluctance, is the stator tooth reluctance, is the air gap reluctance, is the magnetic bridge area reluctance, is the rotor core reluctance, is the permanent magnet magnetic motive force.

[0071] The rotor permanent magnet magnetic motive force is split into permanent magnet characteristic position magnetic motive force distribution data according to uniform distribution, including: the surface-mounted permanent magnet is equally divided into 84 blocks with the same number of poles, and the magnetic motive force provided by each block of permanent magnet is regarded as a constant value, and the spatial waveform is a rectangular wave; taking the center line of the permanent magnet as a reference, representative characteristic positions such as 4 teeth and 5 teeth (corresponding to the permanent magnet edge and the stator tooth alignment or staggered half tooth pitch, respectively) are extracted, the distribution of the permanent magnet magnetic motive force in the air gap circumference at the two characteristic positions is calculated, and two permanent magnet characteristic position magnetic motive force distribution data curves are obtained. Each curve can also be discretized into 360 data points with a step of 1°, which is used to establish the rotor side magnetic circuit model subsequently.

[0072] The stator side large and small pole magnetic circuit model is established according to the large and small pole magnetic motive force distribution data, including: the above-mentioned 360-point “large and small pole” magnetic motive force can be used as an excitation source, and the stator is divided into magnetic flux tubes with different widths according to the unequal-width magnetic circuit idea: narrow magnetic flux tubes can be used in the high-magnetic-motive-force area, and wide magnetic flux tubes can be used in the low-magnetic-motive-force area, so that the magnetic motive force in each magnetic flux tube is relatively uniform; each magnetic flux tube is equivalent to a concentrated magnetic resistance branch, and the branch parameters include the magnetic resistance of the stator tooth, the stator yoke, the air gap, the rotor yoke, the magnetic bridge and the permanent magnet, and finally a node-branch network, namely the stator side “large and small pole” magnetic circuit model, is formed. The model contains 85 nodes and 168 branches, and can directly output the magnetic flux of each branch.

[0073] The rotor side permanent magnet characteristic position magnetic circuit model is established according to the permanent magnet characteristic position magnetic motive force distribution data, including: for the 4-tooth characteristic position and the 5-tooth characteristic position, the permanent magnet, the air gap, the rotor yoke, the magnetic bridge, the stator tooth, the stator yoke and the tooth leakage magnetic path can be abstracted into a T-shaped equivalent magnetic circuit; wherein the permanent magnet is equivalent to a constant voltage source, and the value is equal to the amplitude of the permanent magnet characteristic position magnetic motive force distribution data at the corresponding angle; each section of magnetic resistance is obtained by nonlinear interpolation according to the B-H curve of silicon steel sheet, forming two independent permanent magnet characteristic position equivalent magnetic circuits, which are respectively recorded as 4-tooth model and 5-tooth model, and are used to capture the subtle differences of the rotor side magnetic flux under different tooth alignment modes.

[0074] The common magnetic resistance area between the large and small pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model is identified, including: through automatic comparison of node numbers, the rotor yoke, the magnetic bridge and the triangular area node above the magnetic pole in the stator side “large and small pole” magnetic circuit model can be one-to-one corresponding to the nodes with the same name in the permanent magnet characteristic position magnetic circuit model, and the magnetic resistance connected by the nodes appearing in both models is extracted, which is defined as the common magnetic resistance area; for example, in a 360-slot 84-pole motor, the common area contains 84 sections of rotor yoke magnetic resistance, 84 sections of magnetic bridge magnetic resistance and 84 sections of triangular area magnetic resistance, totaling 252 magnetic resistance elements.

[0075] In the common reluctance region, a key magnetic permeability freezing method is adopted to obtain the frozen common reluctance data.

[0076] Optionally, in the common reluctance region, a key magnetic permeability freezing method is adopted to obtain the frozen common reluctance data, including: taking permanent magnet excitation as the dominant, and freezing the magnetic permeability calculated by the permanent magnet magnetic circuit to the common reluctance region to obtain the frozen common reluctance data.

[0077] Specifically, first, the permanent magnet characteristic position magnetic circuit model can be solved by one-time nonlinear iteration under the excitation of the permanent magnet alone, and the magnetic flux density and relative magnetic permeability of each reluctance element in the common region are extracted after convergence; then these relative magnetic permeability values are directly assigned to the corresponding reluctance in the "large and small pole" magnetic circuit model on the stator side, and remain unchanged in the entire subsequent simultaneous iteration process, so as to lock the dominant role of the permanent magnet on saturation in the common region, forming the frozen common reluctance data; this operation avoids the numerical oscillation caused by repeated updating of the magnetic permeability under double excitation, while ensuring that the saturation level of the key region is dominated by the permanent magnet.

[0078] Among them, the key magnetic permeability freezing method can only freeze the magnetic pole above the triangular region and the rotor yoke reluctance, and the frozen magnetic permeability value is taken from the convergence magnetic permeability of the region under the excitation of the permanent magnet alone.

[0079] Based on the frozen common reluctance data, the parameter correction of the permanent magnet characteristic position magnetic circuit model includes: in the permanent magnet characteristic position magnetic circuit model, the equivalent magnetic motive force source of the permanent magnet is subtracted by a linear weakening amount, and the weakening amount is equal to the d-axis tooth magnetic motive force vector sum of 3-7 stator teeth relative to the permanent magnet. In the permanent magnet characteristic magnetic circuit, the permanent magnet magnetic motive force source is linearly corrected to correspond to the For example, as shown in Figure 7 .

[0080] From the large and small pole method, we have: , , , , Here, the weakening amount is the vector sum of the tooth magnetic motive force relative to each permanent magnet.

[0081] (6)

[0082] Among them, is the correction coefficient when the common tooth magnetic motive force is corrected, and in the corresponding position of the example, the correction coefficient is and need to be corrected according to the position ratio of the permanent magnet relative to the tooth, as shown by the blue line in Figure 7 , the correction coefficient can be obtained Substitute it into formula (6) to obtain .

[0083] The d-axis tooth magnetic motive force corresponding to the four positions can be obtained by the size pole method, and referring to the method shown in FIG. 4, the specific corrected permanent magnet magnetic motive force can be calculated as Figure 7

[0084] (7)

[0085] (8)

[0086] (9)

[0087] (10)

[0088] Optionally, the parameter correction of the permanent magnet characteristic position magnetic circuit model based on the frozen common reluctance data comprises:

[0089] Introducing the linear weakening amount of the stator d-axis magnetic motive force to the permanent magnet magnetic motive force in the permanent magnet characteristic position magnetic circuit model based on the frozen common reluctance data, the linear weakening amount is the vector sum of the magnetic motive force of each tooth relative to the permanent magnet, to obtain the corrected permanent magnet magnetic motive force data;

[0090] Substitute the corrected permanent magnet magnetic motive force data back into the permanent magnet characteristic position magnetic circuit model to obtain the corrected permanent magnet characteristic position magnetic circuit model.

[0091] Specifically, first, the magnetic motive force of each tooth of 3-7 teeth can be calculated by the size pole method, and then the weighted sum of the width proportion of each tooth covered by the center line of the permanent magnet is obtained to obtain the weakening amount ΔF; then in the 4-tooth model and the 5-tooth model, the original permanent magnet magnetic motive force Fpm is uniformly corrected to F'pm=Fpm-ΔF, thereby obtaining the corrected permanent magnet characteristic position magnetic circuit model; the correction simulates the demagnetization effect of the d-axis current on the permanent magnet, so that the rotor side magnetic circuit model can reflect the change of the stator current.

[0092] Optionally, the linear weakening amount can be obtained by: first extracting the d-axis tooth magnetic motive force of a preset number of teeth aligned with the center line of the permanent magnet by the size pole method, and then summing the magnetic motive force vectors of the preset number of teeth and multiplying by a position proportion correction coefficient to obtain the weakening amount.

[0093] The position proportion correction coefficient can be obtained by projecting the center line of the permanent magnet onto the stator teeth and calculating the linear interpolation of the proportion of the tooth width covered by the permanent magnet to the whole tooth width.

[0094] ​The size pole magnetic circuit model is coupled with the modified permanent magnet characteristic position magnetic circuit model, and the magnetic flux density error is less than a preset threshold through iterative calculation, including: the initial value of the magnetic flux density of the stator tooth, air gap and magnetic bridge can be 0.01 T, the magnetic flux distribution of the stator side “size pole” magnetic circuit model is calculated first, then the d-axis current at the same time is substituted into the modified permanent magnet characteristic position magnetic circuit model to obtain the rotor magnetic flux distribution; the two sets of models are coupled through the equal magnetic potential of the common node, the overall magnetic circuit equation is solved, and the new magnetic flux density is obtained; the difference between the new and old magnetic flux densities is compared, and if the maximum relative error is greater than, for example, 0.1%, the magnetic permeability is updated and the iteration is repeated until the error is less than 0.1%, that is, the self-consistent magnetic flux distribution data is obtained; the data contains all branch magnetic fluxes of the stator side and the rotor side, and comprehensively reflects the real magnetic field after cross coupling.

[0095] The iterative calculation of the obtained magnetic circuit follows the flowchart shown in Figure 8 , and the detailed calculation steps are as follows, taking the q-axis as an example:

[0096] Step 1: Set the number of turns , the total current , and the magnetic motive force of each slot under different currents is obtained according to the foregoing. The following calculation solves the q-axis magnetic motive force of the four slots under the characteristic position 5 tooth of No. 1 pole, that is, .

[0097] Before the start of the iterative calculation, the magnetic flux density of the stator tooth and the air gap is set to 0.01 T. If additional magnetic flux density of the magnetic bridge is required for the d-axis magnetic circuit, the initial condition is increased to meet the requirements of iterative solution.

[0098] Step 2: The cross-sectional area of the corresponding part of the magnetic resistance has been obtained in the magnetic resistance calculation. According to the initial setting of the magnetic flux density, the magnetic flux of the stator teeth 1-3 and the air gap 1-2 can be obtained. Considering the conservation of magnetic flux, the magnetic flux density of the stator teeth 4 and the conducting part 1-2 of the silicon steel sheet can be further obtained. Based on this, in addition to the constant air gap permeability, the relative permeability of the stator teeth 1-4 and the silicon steel sheet conducting part 1-2 can be obtained according to Figure 9 . Then, combined with the magnetic resistance calculation method, the magnetic resistance of each part can be obtained.

[0099] Step 3: Substitute the magnetic resistance of the stator tooth, stator yoke, air gap and silicon steel sheet into the magnetic circuit equation. Through one calculation, the magnetic flux corresponding to the magnetic resistance of each part is solved. Combined with the magnetic resistance cross-sectional area of the corresponding part known in the magnetic resistance calculation, the new magnetic flux density of each part can be calculated. Compare the error with the initial set magnetic flux density.

[0100] Step 4: The iterative convergence condition is 0.1%, that is: if the error is greater than 0.1%, the magnetic flux density replaced by and repeat the process of step 2 and 3. Until the error is less than 0.1%, then the magnetic flux calculated by the magnetic circuit equation is considered to satisfy the self-consistent magnetic flux, thus achieving self-consistency. If the computing power allows, the convergence condition of iteration can be taken smaller, and the corresponding solution is more accurate.

[0101] Step 5: According to the final solution of the magnetic flux, the q-axis inductance can be further calculated as where, and are the magnetic fluxes of the stator teeth 1 and 2, respectively.

[0102] Finally, from the self-consistent results, the two stator tooth magnetic fluxes aligned with the d-axis are extracted and , and the d-axis inductance is calculated, for example, where, is the number of turns per phase in series, is the d-axis current; and the is the final output motor design parameter, which can be directly used for electromagnetic performance checking and control strategy optimization of megawatt direct-drive wind turbine permanent magnet synchronous generators, thereby solving the technical problem of large deviation in d-axis inductance calculation caused by ignoring cross coupling in traditional methods, which further affects the accuracy of field-oriented control.

[0103] In summary, the first embodiment of the present application proposes a motor design method based on decoupled cross-fusion magnetic circuit. By splitting the stator d-axis magnetomotive force into "large and small pole" magnetomotive force distribution data according to the asymmetric distribution of the winding, and splitting the rotor permanent magnet magnetomotive force into permanent magnet characteristic position magnetomotive force distribution data according to the uniform distribution, the stator side "large and small pole" magnetic circuit model and the rotor side permanent magnet characteristic position magnetic circuit model are established respectively, which can accurately describe the magnetic flux behavior under asymmetric excitation on the stator side and uniform excitation on the rotor side respectively, solve the problem that the traditional single magnetic circuit model cannot simultaneously consider the characteristics of the two excitation sources, and significantly improve the calculation accuracy of the magnetic field distribution.

[0104] By identifying the common magnetic resistance region between the "large and small pole" magnetic circuit model and the permanent magnet characteristic position magnetic circuit model, and using the key permeability freezing method in the common magnetic resistance region, the permeability of the common magnetic resistance region is frozen mainly by the permanent magnet excitation, which effectively avoids the numerical oscillation and convergence difficulty caused by repeated updating of permeability in the traditional method, and at the same time ensures that the saturation state of the key region (such as the triangular area above the magnetic pole and the rotor yoke) is dominated by the permanent magnet, which truly reflects the saturation characteristics under high electromagnetic load in megawatt direct-drive wind turbine permanent magnet motors.

[0105] In the permanent magnet characteristic position magnetic circuit model, a linear weakening amount of the stator d-axis magnetomotive force to the permanent magnet magnetomotive force is introduced, the weakening amount is set as a vector sum of the magnetomotive force of each tooth relative to the permanent magnet, the demagnetization effect of the d-axis current on the permanent magnet in actual operation can be accurately simulated, the problem that the permanent magnet magnetomotive force cannot be updated with the stator current in the traditional method is solved, and the calculation result is closer to the actual operation state of the motor.

[0106] By combining the "size pole" magnetic circuit model with the corrected permanent magnet characteristic position magnetic circuit model and performing iterative calculation until the magnetic flux density error is less than a preset threshold, self-consistent coupling of the stator side and the rotor side magnetic circuit is realized, and the calculation accuracy of key motor design parameters such as the d-axis inductance is significantly improved.

[0107] In addition, as Figure 10 indicated, the second embodiment of the present application also proposes a motor design device based on decoupled cross-fusion magnetic circuit, for example, comprising: a data acquisition module 201, a magnetic circuit model construction module 202, a data processing module 203, a correction module 204 and a parameter calculation module 205.

[0108] The data acquisition module 201 is used to split the stator d-axis magnetomotive force into size pole magnetomotive force distribution data according to the winding asymmetrical distribution, and split the rotor permanent magnet magnetomotive force into permanent magnet characteristic position magnetomotive force distribution data according to the uniform distribution;

[0109] The magnetic circuit model construction module 202 is used to establish a stator side size pole magnetic circuit model according to the size pole magnetomotive force distribution data, and establish a rotor side permanent magnet characteristic position magnetic circuit model according to the permanent magnet characteristic position magnetomotive force distribution data;

[0110] The data processing module 203 is used to identify a common magnetic resistance region between the size pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model, and obtain frozen common magnetic resistance data by using a key permeability freezing method in the common magnetic resistance region;

[0111] The correction module 204 is used to perform parameter correction on the permanent magnet characteristic position magnetic circuit model based on the frozen common magnetic resistance data, to obtain a corrected permanent magnet characteristic position magnetic circuit model;

[0112] The parameter calculation module 205 is used to combine the size pole magnetic circuit model with the corrected permanent magnet characteristic position magnetic circuit model, to make the magnetic flux density error less than a preset threshold by iterative calculation, to obtain self-consistent magnetic flux distribution data, and to calculate the motor d-axis inductance according to the self-consistent magnetic flux distribution data, to obtain motor design parameters.

[0113] The second embodiment of the present application discloses a motor design method based on the decoupling cross-fusion magnetic circuit realized by the motor design device based on the decoupling cross-fusion magnetic circuit. The method is as described in the first embodiment, and thus will not be described in detail here. Alternatively, each module in the second embodiment and the other operations or functions described above are respectively used to implement the method described in the first embodiment. The motor design device based on the decoupling cross-fusion magnetic circuit provided in the present embodiment has the same beneficial effects as the motor design method based on the decoupling cross-fusion magnetic circuit provided in the first embodiment. For the sake of brevity, the description will not be repeated here.

[0114] As shown in Figure 11 the third embodiment of the present application further provides an electronic device 30, for example, comprising at least one processing unit 31 and at least one storage unit 32. The storage unit 31 stores a computer program, which, when executed by the processing unit 32, causes the processing unit 32 to perform the method described in the first embodiment. The electronic device 30 provided in the present embodiment has the same beneficial effects as the motor design method based on the decoupling cross-fusion magnetic circuit provided in the first embodiment.

[0115] As shown in Figure 12 the fourth embodiment of the present application further provides a computer readable storage medium 40, which stores a computer program. The program, when executed by a processor, implements the steps of the above method. The computer readable storage medium 40 provided in the present embodiment has the same beneficial effects as the motor design method based on the decoupling cross-fusion magnetic circuit provided in the first embodiment.

[0116] The computer readable storage medium can include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a microdrive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic or optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0117] It should be noted that, for the above-mentioned method embodiments, in order to simplify the description, they are all described as a series of action combinations, but those skilled in the art should know that the present application is not limited by the order of the described actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0118] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0119] In several embodiments provided in the present application, it should be understood that the disclosed apparatus can be implemented in other manners. For example, the division of the apparatus embodiments described above is merely illustrative, and the division of the units can be changed according to actual needs. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0120] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments.

[0121] In addition, each functional unit in the embodiments of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0122] The integrated unit, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that makes a contribution to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The aforementioned storage medium includes: a U disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

[0123] Those of ordinary skill in the art can understand that all or part of the steps of the various methods in the above embodiments can be completed by a program instructing relevant hardware, and the program can be stored in a computer readable storage medium, which can include a flash disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a magnetic disk or an optical disk, etc.

[0124] The above-described embodiments are merely illustrative for the present disclosure and do not limit the scope of the present disclosure. Any equivalent changes and modifications made according to the teachings of the present disclosure are to be included within the scope of the present disclosure. Embodiments of the present disclosure will be readily apparent to those skilled in the art in view of the disclosure, and practice thereof, as set forth above. The application is intended to cover any variations, uses or adaptations of the present disclosure including departures from the present disclosure that are within the known art to which the present disclosure pertains. The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

[0125] The technical features of the above embodiments can be combined in any manner. For brevity, not all possible combinations of the technical features in the above embodiments are described, but it should be understood that any combination of the technical features is within the scope of the present disclosure as long as there is no contradiction.

[0126] Those skilled in the art easily understand that the above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A motor design method based on decoupled cross-fusion magnetic circuits, characterized in that, include: The stator d-axis magnetomotive force is divided into magnetomotive force distribution data of large and small poles according to the asymmetrical distribution of the winding, and the rotor permanent magnet magnetomotive force is divided into magnetomotive force distribution data of permanent magnet characteristic position according to the uniform distribution. A stator-side magnetic circuit model for the large and small poles is established based on the large and small pole magnetomotive force distribution data, and a rotor-side magnetic circuit model for the characteristic position of the permanent magnet is established based on the characteristic position magnetomotive force distribution data of the permanent magnet. Identify the common reluctance region between the large and small pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model, and use the key permeability freezing method in the common reluctance region to obtain frozen common reluctance data. Based on the frozen shared magnetoresistive data, the parameters of the permanent magnet characteristic position magnetic circuit model are corrected to obtain the corrected permanent magnet characteristic position magnetic circuit model. The large and small pole magnetic circuit models are combined with the modified permanent magnet characteristic position magnetic circuit models. Through iterative calculation, the magnetic flux density error is made less than a preset threshold to obtain self-consistent magnetic flux distribution data. The motor d-axis inductance is calculated based on the self-consistent magnetic flux distribution data to obtain the motor design parameters.

2. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 1, characterized in that, In the shared magnetoresistance region, a critical permeability freezing method is used to obtain frozen shared magnetoresistance data, including: Using permanent magnet excitation as the primary driver, the permeability calculated from the permanent magnet magnetic circuit is frozen and then assigned to the common magnetic reluctance region to obtain frozen common magnetic reluctance data.

3. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 1, characterized in that, The step of correcting the parameters of the permanent magnet characteristic position magnetic circuit model based on the frozen shared magnetoresistance data to obtain the corrected permanent magnet characteristic position magnetic circuit model includes: Based on the shared magnetoresistive data after freezing, a linear attenuation amount of the stator d-axis magnetomotive force to the permanent magnet magnetomotive force is introduced into the magnetic circuit model of the characteristic position of the permanent magnet. The linear attenuation amount is the vector sum of the magnetomotive forces of each tooth opposite to the permanent magnet, and the corrected permanent magnet magnetomotive force data is obtained. Substituting the corrected magnetomotive force data of the permanent magnet back into the magnetic circuit model of the characteristic position of the permanent magnet, the corrected magnetic circuit model of the characteristic position of the permanent magnet is obtained.

4. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 2, characterized in that, The critical permeability freezing method only freezes the magnetic reluctance of the triangular region above the magnetic pole and the rotor yoke. The frozen permeability value is taken from the convergent permeability of this region under the excitation of the permanent magnet alone.

5. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 3, characterized in that, The method for obtaining the linear attenuation amount includes: firstly, extracting the d-axis tooth magnetomotive force of a preset number of teeth aligned with the center line of the permanent magnet using the major and minor pole method; then, summing the preset number of tooth magnetomotive force vectors and multiplying them by the position ratio correction coefficient to obtain the attenuation amount.

6. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 5, characterized in that, The position ratio correction coefficient is obtained by linearly interpolating the ratio of the permanent magnet coverage tooth width to the total tooth width by projecting the center line of the permanent magnet onto the stator teeth.

7. The motor design method based on decoupled cross-fusion magnetic circuits according to claim 1, characterized in that, The magnetomotive force distribution data of the large and small poles is obtained by superimposing the harmonic components of the magnetomotive force caused by the asymmetry of the number of slots per pole and per phase. The magnetomotive force distribution data of the characteristic position of the permanent magnet is obtained by taking the average value of the magnetomotive force at the characteristic position of 4 or 5 teeth after the permanent magnet is evenly divided into blocks along the circumference.

8. A motor design device based on a decoupled cross-fusion magnetic circuit, characterized in that, include: The data acquisition module is used to split the stator d-axis magnetomotive force into magnetomotive force distribution data of large and small poles according to the asymmetrical distribution of the winding, and to split the rotor permanent magnet magnetomotive force into magnetomotive force distribution data of permanent magnet characteristic positions according to the uniform distribution. The magnetic circuit model construction module is used to establish a stator-side magnetic circuit model based on the distribution data of the large and small pole magnetomotive forces, and to establish a rotor-side magnetic circuit model of the characteristic position of the permanent magnet based on the distribution data of the characteristic position magnetomotive forces of the permanent magnet. The data processing module is used to identify the common magnetic reluctance region between the large and small pole magnetic circuit model and the permanent magnet characteristic position magnetic circuit model, and to use the key permeability freezing method in the common magnetic reluctance region to obtain the frozen common magnetic reluctance data. The correction module is used to correct the parameters of the permanent magnet characteristic position magnetic circuit model based on the frozen shared magnetoresistive data, so as to obtain the corrected permanent magnet characteristic position magnetic circuit model. The parameter calculation module is used to combine the large and small pole magnetic circuit model with the modified permanent magnet characteristic position magnetic circuit model, and through iterative calculation, make the magnetic flux density error less than a preset threshold to obtain self-consistent magnetic flux distribution data. Based on the self-consistent magnetic flux distribution data, the d-axis inductance of the motor is calculated to obtain the motor design parameters.

9. An electronic device, characterized in that, include: A memory and one or more processors connected to the memory, the memory storing a computer program, the processors executing the computer program to implement the motor design method based on decoupled cross-fusion magnetic circuits as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable commands for performing the motor design method based on decoupled cross-fusion magnetic circuits as described in any one of claims 1-7.

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