Design method of axial flux motor capable of simultaneously transmitting electric energy and rotor position information

Abstract

The invention provides a design method of an axial flux motor capable of simultaneously transmitting electric energy and rotor position information, and the design method comprises the steps: designing a basic structure of a main exciter, carrying out the finite element analysis of the basic structure, and determining the technical parameters of the main exciter; determining an initial estimation position of the rotor through the brushless excitation system according to the technical parameters; iteratively determining a second estimation position corresponding to the rotor at each moment, performing first error comparison on all the second estimation positions and the initial estimation position, and determining a final estimation position of the rotor at each moment; second error comparison is carried out on all the final estimation positions and the actual position of the rotor at the corresponding moment, the rationality of the basic structure and the technical parameters is determined according to the comparison result, and the main exciter conforming to the rationality is the axial flux motor. According to the invention, the problems that the size and weight of the main exciter are large after the position sensor is loaded, and the reliability and power density are reduced during starting and power generation are solved.

Description

Technical Field

[0001] The present application relates to the field of AC motor transmission control technology, and in particular to a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information. Background Art

[0002] The brushless synchronous starter generator (BSSG) is a key component of a more electric aircraft. It is an electrically excited brushless synchronous motor, generally composed of a main generator (MG), a rotating rectifier (RR), a main exciter (ME) and a pre-exciter (PE) connected coaxially. The rotors of the main generator and the main exciter are connected through a rotating rectifier.

[0003] The rotor position of the main exciter is the key information for the starting control of the brushless synchronous starter generator. The existing integrated brushless synchronous starter generator system generally obtains the rotor position of the main exciter by installing an additional position sensor. However, due to the harsh working environment of the brushless synchronous starter generator, the failure rate of the additionally installed position sensor increases.

[0004] Secondly, since the brushless synchronous starter generator does not require a position sensor during power generation, installing an additional position sensor will increase the cost, volume and weight of the brushless synchronous starter generator integrated system. To solve the above problems, using the main exciter as the position sensor of the main generator is a more advanced sensorless control strategy. Compared with the main generator, the rated power of the main exciter is relatively low, and the working conditions are relatively simple and stable, which makes this strategy feasible to a certain extent, but the existing main exciter has the following problems:

[0005] Traditional main exciters generally use 400Hz low-frequency AC voltage excitation. The low excitation frequency makes the traditional main exciter bulky, and when position sensorless control is performed, the estimation accuracy of the rotor position is difficult to improve, which greatly reduces the reliability of starting control.

[0006] These unfavorable factors have, to a certain extent, limited the application and promotion of the technical route of using the main exciter as a position sensor for brushless synchronous starter generators.

[0007] Therefore, it is necessary to propose a solution to improve one or more problems existing in the above-mentioned related technical solutions.

[0008] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0009] The present application provides a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information. The design method comprises the following steps:

[0010] Designing the basic structure of the main exciter, and performing finite element analysis on the basic structure to determine the technical parameters of the main exciter;

[0011] According to the technical parameters, a three-phase symmetrical voltage is applied to the stator of the main exciter, and a three-phase stator current of the main exciter is collected, a brushless excitation system is constructed using the three-phase symmetrical voltage and the three-phase stator current, and an initial estimated position of the rotor is determined by the brushless excitation system;

[0012] Iteratively determine the second estimated positions corresponding to the rotor at each moment, and perform first error comparison between all the second estimated positions and the initial estimated positions to determine the final estimated position of the rotor at each moment;

[0013] A second error comparison is performed on all the final estimated positions respectively with the actual positions of the rotor at the corresponding moments, and the rationality of the basic structure and the technical parameters is determined based on the comparison results. The main exciter that meets the rationality is an axial flux motor.

[0014] In an exemplary embodiment of the present application, the step of designing the basic structure of the main exciter includes:

[0015] Design three-phase stator winding and three-phase rotor winding;

[0016] The three-phase stator winding and the stator back iron are coaxially connected, the three-phase rotor winding and the rotor back iron are coaxially connected, the stator back iron and the rotor back iron are fitted and connected, and the three-phase stator winding and the three-phase rotor winding are located in the cavity formed by the fitting connection of the stator back iron and the rotor back iron, so as to construct the basic structure of the main exciter;

[0017] Wherein, the stator back iron and the rotor back iron are coaxial; the three-phase stator winding and the three-phase rotor winding have the same structure.

[0018] In an exemplary embodiment of the present application, the steps of designing the three-phase stator winding and the three-phase rotor winding include:

[0019] Design the topology of single-phase printed circuit board windings;

[0020] Rotating and arranging the topological structure of the single-phase printed circuit board winding to obtain the topological structure of the three-phase printed circuit board winding;

[0021] Importing the topological structure of the three-phase printed circuit board winding into printed circuit board design software, and designing the three-phase stator winding and the three-phase rotor winding;

[0022] Wherein, in the printed circuit board design software, three-phase winding structures at different levels are connected by vias.

[0023] In an exemplary embodiment of the present application, the technical parameters include the rated voltage, rated current, rated speed, stator resistance, rotor resistance, stator inductance and rotor inductance of the main exciter;

[0024] The stator resistance is equal to the rotor resistance, the stator inductance includes stator self-inductance and stator mutual inductance, and the rotor inductance includes rotor self-inductance and rotor mutual inductance.

[0025] In an exemplary embodiment of the present application, the steps of applying a three-phase symmetrical voltage to the stator of the main exciter according to the technical parameters, collecting the three-phase stator current of the main exciter, constructing a brushless excitation system using the three-phase symmetrical voltage and the three-phase stator current, and determining the initial estimated position of the rotor through the brushless excitation system include:

[0026] Converting the three-phase stator current into a current of a first stator shaft and a current of a second stator shaft of the main exciter;

[0027] respectively calculating a derivative of the current of the first stator shaft and a derivative of the current of the second stator shaft;

[0028] According to the calculation results, the back electromotive force of the main exciter is extracted by using a high frequency excitation method;

[0029] Extracting six pairs of envelope lines using the back electromotive force, and respectively extracting the corresponding rotor position of each pair of the envelope lines using a phase-locked loop;

[0030] Selecting any one of the corresponding rotor positions from all the corresponding rotor positions that satisfy a 60-degree angle with each other as the initial estimated position of the rotor;

[0031] Wherein, the brushless excitation system includes a stator two-phase stationary α s -β s Coordinate system, actual rotor two-phase stationary α r -β r Coordinate system, estimate the rotor two-phase stationary Coordinate system and two-phase synchronously rotating dq coordinate system.

[0032] In an exemplary embodiment of the present application, the step of iteratively determining the second estimated position corresponding to the rotor at each moment, and performing a first error comparison between all the second estimated positions and the initial estimated position, and determining the final estimated position of the rotor at each moment includes:

[0033] Iteratively performing the step of extracting the corresponding rotor position of each pair of the envelope lines at each moment to obtain a plurality of the second estimated positions;

[0034] The first error comparison is performed on all the second estimated positions respectively with the initial estimated position, and the final estimated position of the rotor at each moment is determined according to the result of the first error comparison.

[0035] In an exemplary embodiment of the present application, the expressions of the currents of the first stator shaft and the second stator shaft are:

[0036]

[0037] in, represents the current of the first stator shaft, represents the current of the second stator shaft, i esA Represents the first phase stator current of the main exciter, i esB represents the second phase stator current of the main exciter, i esC represents the third-phase stator current of the main exciter, α s represents the first stator axis, β s Indicates the second stator shaft.

[0038] In an exemplary embodiment of the present application, the expression of the back electromotive force is:

[0039]

[0040] in represents the back electromotive force of the d-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, It represents the back electromotive force of the q-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, L es Represents the stator inductance of the main exciter, M em represents the stator mutual inductance of the main exciter, represents the derivative of the current in the first stator axis, represents the derivative of the current of the second stator shaft.

[0041] In an exemplary embodiment of the present application, the step of performing the first error comparison on all the second estimated positions and the initial estimated position, and determining the final estimated position of the rotor according to the result of the first error comparison comprises:

[0042] An estimation error checking mechanism is introduced to compare the first error of the second estimated position at each moment with the initial estimated position, and all the second estimated positions corresponding to the minimum error value are used as the final estimated position of the rotor at each moment.

[0043] Beneficial effects:

[0044] The present application provides a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information, which has at least the following beneficial effects:

[0045] (1) The present application redesigns the basic structure of the main exciter by adopting an axial flux structure and introduces printed circuit board technology to manufacture three-phase stator windings and three-phase rotor windings, thereby greatly reducing the volume and weight of the main exciter;

[0046] (2) Based on the basic structure of the newly designed main exciter, the present application uses the main exciter as the position sensor of the main generator, and obtains the initial estimated position of the rotor and the second estimated position of the rotor at each moment in turn, and compares the first error between the two estimated positions to determine the final estimated position of the rotor at each moment. This method has high estimation accuracy and greatly improves the reliability of the brushless synchronous starting and generating integrated system during the starting control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 A block diagram of an existing brushless synchronous starting and generating integrated system is shown;

[0049] Figure 2 A schematic diagram showing the steps of a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information in an exemplary embodiment of the present application;

[0050] Figure 3 A schematic diagram showing the topological structure of a single-phase printed circuit board winding in an exemplary embodiment of the present application;

[0051] Figure 4 A schematic diagram showing the topological structure of a three-phase printed circuit board winding in an exemplary embodiment of the present application;

[0052] Figure 5A schematic diagram showing the structure of a three-phase stator winding or a three-phase rotor winding in an exemplary embodiment of the present application is shown;

[0053] Figure 6 A schematic diagram showing the structure of a stator back iron in an exemplary embodiment of the present application is shown;

[0054] Figure 7 A schematic diagram showing the structure of a rotor back iron in an exemplary embodiment of the present application is shown;

[0055] Figure 8 A schematic diagram showing the basic structure of a main exciter in an exemplary embodiment of the present application;

[0056] Fig. 9 A schematic diagram showing a brushless excitation system in an exemplary embodiment of the present application;

[0057] Fig.10 A schematic diagram showing a flow chart of determining a final estimated position of a rotor of a main exciter in an exemplary embodiment of the present application;

[0058] Fig.11 A graph showing the current of the stator of the main exciter in an exemplary embodiment of the present application;

[0059] Fig.12 A graph showing a derivative of a current of a stator of a main exciter in an exemplary embodiment of the present application;

[0060] Fig.13 A schematic diagram showing six pairs of envelopes corresponding to the derivative of the current of the first stator shaft in an exemplary embodiment of the present application;

[0061] Fig.14 A schematic diagram showing six pairs of envelopes corresponding to the derivative of the current of the second stator shaft in an exemplary embodiment of the present application;

[0062] Fig.15 A schematic diagram showing the actual position of the rotor of the main exciter in an exemplary embodiment of the present application;

[0063] Fig.16 A schematic diagram showing a final estimated position of a rotor of a main exciter in an exemplary embodiment of the present application;

[0064] Fig.17 A schematic diagram showing the result of second error comparison between all final estimated positions and the actual position of the rotor in an exemplary embodiment of the present application;

[0065] Fig.18 A schematic diagram showing an estimated value of the rotation speed of the main exciter in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0066] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0067] In addition, the accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0068] like Figure 1 As shown, the brushless synchronous starter generator is generally composed of a main generator, a rotating rectifier, a main exciter and an auxiliary exciter connected coaxially in sequence. During starting, first, a three-phase AC voltage is applied to the stator of the main exciter, and a three-phase AC current is induced on the rotor of the main exciter. Then, after rectification by the rotating rectifier, the main generator obtains a DC excitation current, which can then be driven to start the main generator through an inverter. During power generation, the permanent magnet rotor of the auxiliary exciter rotates coaxially with the main generator, inducing a three-phase AC current on the stator of the auxiliary exciter, thereby powering the stator of the main exciter, and the rotor of the main exciter then induces a three-phase AC current. Finally, after rectification by the rotating rectifier, the main generator obtains a DC excitation current, which can then generate power. In order to solve the problem that the power density and reliability of the integrated brushless synchronous starter generator system are reduced when the position sensor is installed for starting and generating electricity due to the large size and weight of the main exciter of the conventional brushless synchronous starter generator, a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information is proposed, such as Figure 2 As shown, the method may include the following steps:

[0069] Step S101: designing the basic structure of the main exciter, and performing finite element analysis on the basic structure of the main exciter to determine the technical parameters of the main exciter.

[0070] Step S102: According to the technical parameters, a three-phase symmetrical voltage is applied to the stator of the main exciter, and the three-phase stator current of the main exciter is collected. A brushless excitation system is constructed using the three-phase symmetrical voltage and the three-phase stator current, and the initial estimated position of the rotor is determined by the brushless excitation system.

[0071] Step S103: iteratively determine the second estimated positions corresponding to the rotor at each moment, and perform first error comparisons on all the second estimated positions and the initial estimated positions to determine the final estimated position of the rotor at each moment.

[0072] Step S104: perform a second error comparison on all final estimated positions and the actual positions of the rotors at corresponding moments, and determine the rationality of the basic structure and technical parameters according to the comparison results. The main exciter that meets the rationality is the axial flux motor.

[0073] The embodiment of the present application provides a design method for an axial flux motor that transmits electric energy and rotor position information simultaneously, which has at least the following beneficial effects:

[0074] (1) The present application redesigns the basic structure of the main exciter by adopting an axial flux structure and introduces printed circuit board technology to manufacture three-phase stator windings and three-phase rotor windings, thereby greatly reducing the volume and weight of the main exciter;

[0075] (2) Based on the basic structure of the newly designed main exciter, the present application uses the main exciter as the position sensor of the main generator, and obtains the initial estimated position of the rotor and the second estimated position of the rotor at each moment in turn, and compares the first error between the two estimated positions to determine the final estimated position of the rotor at each moment. This method has high estimation accuracy and greatly improves the reliability of the brushless synchronous starting and generating integrated system during the starting control process.

[0076] The present application proposes a design method for an axial flux motor that simultaneously transmits electric energy and rotor position information. The design method is described in more detail below.

[0077] Since the existing main exciter is a radial flux motor, an alternating current of about 400 Hz is generally used for excitation. The stator core and end windings of this motor structure are large, and the excitation frequency is low, which makes the main exciter relatively bulky, which not only increases the volume, weight and cost of the brushless synchronous starter generator integrated system, but also is not conducive to improving the power density of the brushless synchronous starter generator. In the process of finding a solution to this technical problem, we found that in the existing motor structure, the axial flux motor is a motor with a short axial dimension, light weight, and high power density. Especially when the printed circuit board (PCB) technology is introduced, the excitation frequency of the main exciter is greatly improved, and the volume is significantly reduced. Therefore, in step S101 of this embodiment, the basic structure of the main exciter is specifically designed. Step S101 of this embodiment may include the following sub-steps:

[0078] Sub-step S1011: Design three-phase stator windings and three-phase rotor windings.

[0079] Furthermore, first, if Figure 3 As shown in Figure 1, design the topology of the single-phase printed circuit board winding. Figure 3 As shown, take the topological structure of 10 pairs of single-phase printed circuit board windings as an example; then, Figure 4 As shown, the topological structure of the single-phase printed circuit board winding is rotated and arranged to obtain the topological structure of the three-phase printed circuit board winding; finally, as shown Figure 5 As shown, the topological structure of the three-phase printed circuit board winding is imported into the printed circuit board design software, and the three-phase stator winding and the three-phase rotor winding are designed. In the printed circuit board design software, the three-phase winding structures at different levels are connected by vias.

[0080] Furthermore, the printed circuit board winding mentioned in this embodiment adopts FR-4 sheet material, so that it can maintain high mechanical strength while maintaining low cost, and has good insulation ability in dry or humid environment. At the same time, a multi-layer PCB structure is adopted, preferably more than 10 layers, and the thickness of each layer of copper foil needs to be greater than 2 ounces, so as to ensure that the three-phase stator winding and the three-phase rotor winding have sufficient current capacity. The outer diameter of the PCB is 120mm and the inner diameter is 15mm, which can ensure that the stator winding and the rotor winding have sufficient transmission power, and can also ensure the reasonable installation of the three-phase interface and the rotating shaft of the three-phase stator winding and the three-phase rotor winding.

[0081] Sub-step S1012: respectively designing the structures of the stator back iron and the rotor back iron of the main exciter.

[0082] Furthermore, if Figure 6 and Figure 7 As shown in the figure, the thickness of the stator back iron and the rotor back iron are both 10mm, the outer diameter is 120mm, and the material of the stator back iron and the rotor back iron are both manganese zinc ferrite. Manganese zinc ferrite is used here because this material can effectively reduce the loss value and reduce the heat generated by the main exciter in a high frequency environment.

[0083] Sub-step S1013: Figure 8 As shown, the three-phase stator winding and the stator back iron are coaxially connected, the three-phase rotor winding and the rotor back iron are coaxially connected, the stator back iron and the rotor back iron are fitted and connected, and the three-phase stator winding and the three-phase rotor winding are located in the cavity formed by the stator back iron and the rotor back iron, so as to construct the basic structure of the main exciter.

[0084] Among them, the three-phase stator winding and the three-phase rotor winding have the same structure. The stator back iron and the rotor back iron are coaxial. That is, in the final basic structure, the stator back iron, the three-phase stator winding, the three-phase rotor winding and the rotor back iron are all coaxial.

[0085] Furthermore, mechanical limiting is used to ensure that the three-phase stator winding and the three-phase rotor winding always maintain a spacing of 1 mm, the spacing between the stator back iron and the stator winding is 0.5 mm, and the spacing between the rotor back iron and the rotor winding is also 0.5 mm.

[0086] Sub-step S1014: Perform finite element analysis on the basic structure of the main exciter to determine the technical parameters of the main exciter.

[0087] Furthermore, the finite element analysis of the basic structure of the main exciter is carried out to verify the reliability and safety of the designed main exciter and obtain reasonable technical parameters on this basis.

[0088] Furthermore, the technical parameters of the main exciter include the rated voltage, rated current, rated speed, stator resistance, rotor resistance, stator inductance and rotor inductance of the main exciter.

[0089] Among them, the stator resistance is equal to the rotor resistance, the stator inductance includes the stator self-inductance and the stator mutual inductance, and the rotor inductance includes the rotor self-inductance and the rotor mutual inductance.

[0090] In step S102 of this embodiment, according to the technical parameters, a three-phase symmetrical voltage is applied to the stator of the main exciter, and the three-phase stator current of the main exciter is collected. A brushless excitation system is constructed using the three-phase symmetrical voltage and the three-phase stator current, and the initial estimated position of the rotor is determined by the brushless excitation system.

[0091] like Fig. 9 As shown in the figure, in the brushless excitation system of BSSG, ME converts the AC power of the pre-excitation machine into DC power through a rotating rectifier and transmits it to the rotor winding of MG to provide excitation current for the main generator. esA,B,C is the three-phase stator voltage of ME, i esA,B,C is the three-phase stator current of ME, i era,b,c is the rotor current of ME, i f is the excitation current of MG. s Axis is the first stator axis, β s The axis is the second stator axis, and the two are used to form the stator two-phase stationary α s -β s Coordinate system. r The axis is the first rotor axis, β r The shaft is the second rotor shaft, and the two are used to form the actual rotor two-phase stationary α r -β r Coordinate System and Estimation of Rotor Two-Phase Stationary Coordinate system. The two-phase synchronous rotating dq coordinate system includes the d-axis and the q-axis, θ er represents the initial estimated position of the rotor of the ME, represents the second estimated position of the rotor, Δθer A first error comparison is represented between the second estimated position and the initial estimated position.

[0092] like Fig.10 As shown, step S102 of this embodiment includes the following sub-steps:

[0093] Sub-step S1021: Apply a three-phase symmetrical voltage to the stator of the main exciter, and collect the three-phase stator current through a current sensor.

[0094] Sub-step S1022: Convert the three-phase stator current into the current of the first stator shaft and the current of the second stator shaft of the main exciter.

[0095] Furthermore, the expressions of the currents of the first stator shaft and the second stator shaft are:

[0096]

[0097] in, represents the current of the first stator shaft, represents the current of the second stator shaft, i esA Represents the first phase stator current of the main exciter, i esB represents the second phase stator current of the main exciter, i esC represents the third-phase stator current of the main exciter, α s represents the first stator axis, β s Indicates the second stator shaft.

[0098] Sub-step S1023: Calculate the derivative of the current of the first stator shaft and the derivative of the current of the second stator shaft respectively.

[0099] Sub-step S1024: According to the calculation results, the back electromotive force of the main exciter is extracted using a high-frequency excitation method.

[0100] Furthermore, the expression of back electromotive force is:

[0101]

[0102] in, represents the back electromotive force of the d-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, It represents the back electromotive force of the q-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, L es Represents the stator inductance of the main exciter, M em represents the stator mutual inductance of the main exciter, represents the derivative of the current in the first stator axis, represents the derivative of the current of the second stator shaft.

[0103] Sub-step S1025: extract six pairs of envelopes using back electromotive force, and extract the corresponding rotor position of each pair of envelopes using a phase-locked loop. Sub-step S1025 specifically includes the following process:

[0104] Firstly, six pairs of envelopes are extracted according to the back electromotive force of the main exciter.

[0105] Secondly, a phase locked loop (PLL) is used to extract the corresponding rotor position of each pair of envelopes. In this embodiment, six phase locked loops are used to extract the corresponding rotor positions of the six pairs of envelopes.

[0106] Sub-step S1026: From all corresponding rotor positions that satisfy the 60-degree angle, select any corresponding rotor position as the initial estimated position of the rotor. That is to say, the 60-degree angle means that each of the six pairs of envelopes obtains a corresponding corresponding rotor position through a phase-locked loop, and among the six rotor positions, if there are at least two adjacent corresponding rotor positions whose angles satisfy the 60-degree arrangement, then one of the rotor positions is selected as the initial estimated position of the rotor.

[0107] Among them, the brushless excitation system includes a stator two-phase stationary α s -β s Coordinate system, actual rotor two-phase stationary α r -β r Coordinate system, estimate the rotor two-phase stationary Coordinate system and two-phase synchronously rotating dq coordinate system.

[0108] In step S103 of this embodiment, the second estimated position corresponding to the rotor at each moment is determined iteratively, and all the second estimated positions are compared with the initial estimated position by first error to determine the final estimated position of the rotor at each moment. Step S103 of this embodiment includes the following sub-steps:

[0109] Sub-step S1031: iteratively perform the step of extracting the corresponding rotor position of each pair of envelope curves at each moment to obtain a plurality of second estimated positions.

[0110] Sub-step S1032: perform a first error comparison on all second estimated positions and the initial estimated position, and determine the final estimated position of the rotor at each moment according to the result of the first error comparison. Sub-step S1032 specifically includes: introducing an estimation error checking mechanism, performing a first error comparison on the second estimated position at each moment and the initial estimated position, and taking all second estimated positions corresponding to the minimum error value as the final estimated position of the rotor at each moment.

[0111] In step S104 of the present embodiment, a second error comparison is performed on all the final estimated positions respectively with the actual positions of the rotors at the corresponding moments, that is, a second error comparison is performed on the final estimated positions of the rotors at each moment respectively with the actual positions of the rotors at the corresponding moments, and the rationality of the basic structure and technical parameters of the main exciter is determined based on the result of the second error comparison, and the main exciter that meets the rationality is used as an axial flux motor.

[0112] Step S104 of this embodiment specifically includes: calculating the error value between the final estimated position of the rotor and the actual position of the rotor at each moment, judging whether all error values ​​meet the design accuracy requirements of the axial flux motor mentioned in this application, and after determining that the accuracy requirements of all final estimated positions are met, the basic structure and technical parameters of the main exciter can be determined.

[0113] In order to verify the effectiveness of the design method of an axial flux motor for simultaneously transmitting electric energy and rotor position information proposed in this application, the following simulation experiment was carried out.

[0114] Simulation parameter settings

[0115] The simulation software used is: MATLAB / Simulink and ANSYS for joint simulation. The three-phase power supply module provided by MATLAB / Simulink is used to apply 35V / 20KHz three-phase symmetrical high-frequency voltage excitation to the stator winding of the designed main exciter, and the current sensor is used to collect the three-phase stator current i of the stator winding of the main exciter. esA ,i esB and i esC .

[0116] like Fig.11 and Fig.12 The first stator axis α is obtained by formula (1): s Current and current The derivative of Second stator shaft β s Current and current The derivative of

[0117] here, Fig.11 The horizontal axis is time, the unit is s, and the vertical axis is the current of the stator shaft of the main exciter, the unit is A.

[0118] Fig.12 The horizontal axis is time, the unit is s, and the vertical axis is the derivative of the stator current of the main exciter, the unit is A / s.

[0119] Afterwards, the back electromotive force of the main exciter is extracted by formula (2), and the six pairs of envelopes are extracted respectively using the back electromotive force.

[0120] Fig.13 The envelope corresponding to the derivative of the current of the first stator shaft is extracted by using the back electromotive force of the main exciter, Fig.14 The envelope curves corresponding to the derivatives of the current of the second stator shaft extracted respectively by utilizing the back electromotive force of the main exciter are shown.

[0121] Finally, a second estimated position step is performed, and the error between the initial estimated position and the second estimated position is compared to obtain a final estimated position of the rotor of the main exciter.

[0122] Fig.15 , Fig.16 and Fig.17 The actual position of the main exciter rotor, the final estimated position, and the result of the second error comparison between the two are shown in turn. Figure 15-17 It can be seen that the estimation error of the rotor position is within 0.5 degrees, which means that the rotor position estimation using the method proposed in this application has high accuracy.

[0123] Fig.18 The speed range provided by this simulation test is 0-1000 rpm. The estimated value of the speed at each moment forms an inclined straight line, indicating that the speed of the main exciter increases steadily. Since the estimated value of the speed is obtained based on the estimated angle, the steady increase in the speed of the main exciter to a certain extent illustrates the correctness of the estimated angle.

[0124] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0125] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0126] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and these modifications or substitutions should be included in the protection scope of the present application.

[0127] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

Claims

1. A design method for an axial flux motor that transmits electric energy and rotor position information simultaneously, characterized in that: The design method includes the following steps: Designing the basic structure of the main exciter, and performing finite element analysis on the basic structure to determine the technical parameters of the main exciter; According to the technical parameters, a three-phase symmetrical voltage is applied to the stator of the main exciter, and a three-phase stator current of the main exciter is collected, a brushless excitation system is constructed using the three-phase symmetrical voltage and the three-phase stator current, and an initial estimated position of the rotor is determined by the brushless excitation system; Iteratively determine the second estimated positions corresponding to the rotor at each moment, and perform first error comparison between all the second estimated positions and the initial estimated positions to determine the final estimated position of the rotor at each moment; A second error comparison is performed on all the final estimated positions respectively with the actual positions of the rotor at the corresponding moments, and the rationality of the basic structure and the technical parameters is determined based on the comparison results. The main exciter that meets the rationality is an axial flux motor.

2. The design method of the axial flux motor according to claim 1, characterized in that: The steps of designing the basic structure of the main exciter include: Design three-phase stator winding and three-phase rotor winding; The three-phase stator winding and the stator back iron are coaxially connected, the three-phase rotor winding and the rotor back iron are coaxially connected, the stator back iron and the rotor back iron are fitted and connected, and the three-phase stator winding and the three-phase rotor winding are located in the cavity formed by the fitting connection of the stator back iron and the rotor back iron, so as to construct the basic structure of the main exciter; Wherein, the stator back iron and the rotor back iron are coaxial; the three-phase stator winding and the three-phase rotor winding have the same structure.

3. The design method of the axial flux motor according to claim 2, characterized in that: The steps of designing the three-phase stator winding and the three-phase rotor winding include: Design the topology of single-phase printed circuit board windings; Rotating and arranging the topological structure of the single-phase printed circuit board winding to obtain the topological structure of the three-phase printed circuit board winding; Importing the topological structure of the three-phase printed circuit board winding into printed circuit board design software, and designing the three-phase stator winding and the three-phase rotor winding; Wherein, in the printed circuit board design software, three-phase winding structures at different levels are connected by vias.

4. The design method of the axial flux motor according to claim 3, characterized in that: The technical parameters include the rated voltage, rated current, rated speed, stator resistance, rotor resistance, stator inductance and rotor inductance of the main exciter; The stator resistance is equal to the rotor resistance, the stator inductance includes stator self-inductance and stator mutual inductance, and the rotor inductance includes rotor self-inductance and rotor mutual inductance.

5. The design method of the axial flux motor according to claim 4, characterized in that: The steps of applying a three-phase symmetrical voltage to the stator of the main exciter according to the technical parameters, collecting the three-phase stator current of the main exciter, constructing a brushless excitation system using the three-phase symmetrical voltage and the three-phase stator current, and determining the initial estimated position of the rotor through the brushless excitation system include: Converting the three-phase stator current into a current of a first stator shaft and a current of a second stator shaft of the main exciter; respectively calculating a derivative of the current of the first stator shaft and a derivative of the current of the second stator shaft; According to the calculation results, the back electromotive force of the main exciter is extracted by using a high frequency excitation method; Extracting six pairs of envelope lines using the back electromotive force, and respectively extracting the corresponding rotor position of each pair of the envelope lines using a phase-locked loop; Selecting any one of the corresponding rotor positions from all the corresponding rotor positions that satisfy a 60-degree angle with each other as the initial estimated position of the rotor; Wherein, the brushless excitation system includes a stator two-phase stationary α s -β s Coordinate system, actual rotor two-phase stationary α r -β r Coordinate system, estimate the rotor two-phase stationary Coordinate system and two-phase synchronously rotating dq coordinate system.

6. The design method of the axial flux motor according to claim 5, characterized in that: The steps of iteratively determining the second estimated positions corresponding to the rotor at each moment, and performing first error comparison between all the second estimated positions and the initial estimated positions, and determining the final estimated position of the rotor at each moment include: Iteratively performing the step of extracting the corresponding rotor position of each pair of the envelope lines at each moment to obtain a plurality of the second estimated positions; The first error comparison is performed on all the second estimated positions respectively with the initial estimated position, and the final estimated position of the rotor at each moment is determined according to the result of the first error comparison.

7. The design method of the axial flux motor according to claim 6, characterized in that: The expressions of the currents of the first stator shaft and the second stator shaft are: in, represents the current of the first stator shaft, represents the current of the second stator shaft, i edA Represents the first phase stator current of the main exciter, i esB Represents the second phase stator current of the main exciter, i esC represents the third phase stator current of the main exciter, α s represents the first stator axis, β s Indicates the second stator shaft.

8. The design method of the axial flux motor according to claim 7, characterized in that: The expression of the back electromotive force is: in, represents the back electromotive force of the d-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, It represents the back electromotive force of the q-axis of the main exciter in the two-phase synchronous rotating dq coordinate system, L es Represents the stator inductance of the main exciter, M em represents the stator mutual inductance of the main exciter, represents the derivative of the current in the first stator axis, represents the derivative of the current of the second stator shaft.

9. The design method of the axial flux motor according to claim 8, characterized in that: The step of performing the first error comparison on all the second estimated positions and the initial estimated position, and determining the final estimated position of the rotor at each moment according to the result of the first error comparison comprises: An estimation error checking mechanism is introduced to compare the first error of the second estimated position at each moment with the initial estimated position, and all the second estimated positions corresponding to the minimum error value are used as the final estimated position of the rotor at each moment.

Images