Method and device for determining noise and electromagnetic vibration levels

Abstract

The present invention relates to a method and device for determining the noise and electromagnetic vibration levels of a machine equipped with an electric motor. For this purpose, a computer means obtains a set of load cases and eigenmodes of the machine (31, 32), determines a significant subset (33), obtains a set of relevant nodes (34), calculates a set of frequency response functions restricted to the relevant nodes (35), obtains a set of operating points and magnetic states of the machine (36, 37), determines a set of operating loads of the machine (38), and determines the noise and electromagnetic vibration levels based on the frequency response functions and operating loads (39).

Description

[Technical Field]

[0001] This invention relates to virtual prototyping of an electrical system that emits acoustic noise originating from electromagnetic force.

[0002] More specifically, the present invention relates to a method for determining noise and vibration levels originating from electromagnetic forces in a machine equipped with an electric motor.

[0003] The present invention also relates to a device for carrying out such a method.

[0004] In addition, the present invention relates to designing a machine equipped with an electric motor that carries out such a method.

[0005] Therefore, the present invention can find many advantageous applications in the design of electrical machinery related to sectors such as transportation (automobile, rail, and maritime), industry, energy, medical, and household applications. [Background technology]

[0006] All mechanical systems generate noise. Resonance between structural modes and excitation forces is very often the primary cause of, or significantly contributing to, noise and vibration problems. The source of these resonances is a specific component of the system, or the system or structure as a whole.

[0007] These noise and vibration phenomena occur in operating machinery, particularly during the rotational motion of rotating machinery. High levels of noise or vibration can result in a loss of acoustic comfort, a loss of manual comfort, or even health problems if exposed to noise for extended periods. They can also cause failure or damage to the system's physical structure due to fatigue.

[0008] In the simplest cases, the source of resonant vibration can be identified empirically (e.g., a problem with the tightening of mechanical parts), or the noise can be limited by properly adapting the system's structure (e.g., adding an acoustic cowling). Identifying this source becomes rapidly more complex in the case of noise originating from electromagnetic forces, due to the complexity of the excitation forces involved.

[0009] The applicant has observed that solutions proposed to date for predicting vibrations originating from the magnetic force of a given machine are based on numerical simulations combining different finite element software commonly used in the fields of low-frequency electromagnetism, structural mechanics, and linear acoustics. These solutions, therefore, provide a comprehensive calculation of the magnetic force at variable speed in the first step, a calculation of vibrations by mode expansion in the second step, and an evaluation of acoustic radiation around the machine in the third step. While these solutions make it possible to obtain accurate results for the level of vibration generated by a given machine, they require very long computation times, about 15 hours per machine. Thus, such approaches are incompatible with the design phase of electromechanics, as each iteration or design change requires time-consuming simulations to estimate electromagnetic noise. The applicant also proposes that other complementary approaches based on approximate calculations of magnetic forces or electromagnetic vibration synthesis have been developed, which allow for the use of structural linearity to reduce computation time. These can reduce computation time to about 1.5 hours in the simplest cases.

[0010] However, the applicant points out that these calculations are still heavily loaded and consequently performed in memory, becoming even heavier in the case of complex loads, such as machines with inclined rotors. Furthermore, these solutions only provide a final estimate of the total amount of noise produced by the machine. Therefore, it is difficult to identify ways to reduce the noise, and improving the machine design requires increasing the number of simulations to find solutions that minimize the noise.

[0011] The applicant submits that the current solutions have a very long calculation time that is incompatible with an iterative design approach, a large memory size both during the calculation (on RAM) and at the output of the calculation (on the hard disk), mesh projection, digital interpolation, and vulnerability to numerical noise in the results due to spectral spreading, and do not provide information or discrimination regarding the sources of noise and vibration derived from magnetic forces.

[0012] Therefore, the applicant submits that the solutions for determining the noise and vibration levels derived from electromagnetic forces are not satisfactory, and in particular, are not suitable for the needs of industrial design and prototyping. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] The present invention aims to improve the situation described above. MEANS FOR SOLVING THE PROBLEMS

[0014] The present invention relates in particular to a method and an apparatus for determining the noise and vibration levels derived from the electromagnetic forces of an electric motor machine having a mechanical structure, the machine comprising a rotor and a stator, the rotor and the stator being separated by an air gap, the method being implemented by at least one processor, the method comprising The steps include: obtaining first data representing a set of loading cases associated with a machine, where each loading case corresponds to a component of a magnetic load by a mathematical basis, preferably a decomposition in a Fourier series; The steps include: obtaining second data representing a set of eigenmodes of the mechanical structure, The steps include determining a subset of load cases and significant eigenmodes from a set of load cases and a set of eigenmodes, • A third step of obtaining data representing a set of related nodes associated with the mechanical structure, The steps include: calculating a set of frequency response functions by mode expansion restricted to a set of related nodes, as well as a subset of load cases and significant eigenmodes; The step of obtaining a fourth set of data representing a first set of operating points of the machine, wherein each operating point is associated with the torque and speed of the machine, The step of obtaining a fifth set of data representing a set of magnetic states of a machine, wherein each magnetic state in the set of magnetic states is associated with the operating point, • A step of determining the set of operating loads from the set of magnetic states, The steps include: determining information representing noise and vibration levels originating from the electromagnetic forces of the machine from a set of operating loads and a set of frequency response functions; Includes.

[0015] Here, it is understood that the load case corresponds to the component of force applied to the electromachine, particularly at different points in the rotor and stator. The magnetic load of the electromachine is defined, for example, based on the design parameters of the electromachine, i.e., these follow the structure of the magnetic circuit of the electromachine. The load case is associated with an arbitrarily fixed amplitude or operating level, for example, a unit load, i.e., an amplitude of 1N for the sake of simplifying calculations.

[0016] Each load case includes all of the following information, for example: • Load type: force or torque, For example, the direction of application of force: radial, circumferential, axial, • Applied structure: rotor or stator, • Wavenumber: r=0, 1, 2, etc.

[0017] According to one particular embodiment, the set of load cases is limited to only the lowest wavenumber present in the machine, for example, excitation with wavenumber r=0. Those skilled in the art will understand that the lowest wavenumber is related to the most important excitation, and this limitation can limit unnecessary calculations without affecting the accuracy of the results.

[0018] Furthermore, it is understood that the set of eigenmodes corresponds to a representation of the harmonic vibration behavior of the machine in a manner appropriate for vibration analysis. Each eigenmode is characterized, for example, by mode deformation, natural frequency, and mode damping. Those skilled in the art will understand that any response to excitation corresponds to a linear combination of eigenmodes. The determination of load cases and subsets of significant eigenmodes corresponds to the identification of load case and eigenmode combinations that result in significant vibrations. In other words, this determination makes it possible to identify, for each load case, the mode with the shape closest to the load case. This design therefore makes it possible to reduce the set of load cases and the set of eigenmodes of elements that contribute significantly to noise originating from electromagnetic forces, and thus avoid extraneous calculations.

[0019] Furthermore, it is understood that the set of relevant nodes corresponds to the reduction to computationally relevant nodes for all nodes resulting from the mesh of the machine's structure. These nodes may be related to the visualization of the mode of interest, the execution of calculations, or the verification of design criteria, such as vibration standards. The relevant nodes are reduced to, for example, the tooth head of an electric motor to which the majority of the magnetic force is applied, the fixed points of a machine to which vibration design criteria are applied, and the envelope points of a structure to which the normal vibrations cause acoustic radiation. The mode deformations of the subset of eigenmodes determined above are reduced to this set of relevant nodes; that is, mode deformations are calculated only for the set of relevant nodes during the calculation of the set of frequency response functions.

[0020] Those skilled in the art will understand that a set of frequency response functions makes it possible to obtain, for each node in the set of relevant nodes, the amplitude of vibration or sound pressure amplitude under the effect of a load case applied to the eigenmode, for example.

[0021] The principle of modal expansion is known from prior art and is a major factor in computation time, especially at high frequencies where modal density is large. However, restricting this principle to related modes, related excitations, and related nodes allows for a significant reduction in the computation time and memory load associated with noise determination without affecting the accuracy of the results.

[0022] This first set of steps makes it possible to characterize the structure of an electromachine and its vibrational behavior.

[0023] Secondly, or for example in parallel with the first set of steps, the second set of steps allows for characterizing the level of the machine's actual operating force, i.e., the complex amplitude (norm and phase) of each case of magnetic load applied to the machine along the machine's operating point.

[0024] Therefore, it is understood that the set of operating points, i.e., the combination of torque and speed of an electric motor, corresponds to the various speeds that the machine may follow as it operates. Thus, the set of magnetic states corresponds to the magnetic flux and / or forces within the machine that are generated when the machine operates according to a given operating point.

[0025] Each magnetic state includes a magnetic force torsor for each stator tooth, for example, including radial force, circumferential force, and moment. Thus, the set of magnetic states allows for the determination of a set of operating levels and the evaluation of the intensity of a given load, for example, in units of N, according to the operating point.

[0026] In other words, a set of magnetic states corresponds to a set of excitation forces associated with each operating point.

[0027] Therefore, the set of operating loads can be determined, for example, as a function of the set of magnetic states by integrating the Maxwell tensor over the tooth pitch from the distribution of magnetic flux in the middle of the air gap. Another, more precise method for calculating the operating loads is to apply a virtual work method based on the distribution of magnetic fields on the magnetic mesh, and then integrate the torsor of the force for each tooth. Regardless of the method chosen for calculating the magnetic torsor, a Fourier series decomposition of the torsor is performed with the aim of determining the amplitude in units N and the phase in units of radians for each load case (e.g., a radial force of wavenumber r=0 is applied to the stator) and each operating point. Thus, determining the information representing the noise and vibration levels originating from electromagnetic forces corresponds to the correspondence between the frequency response function, i.e., the vibrations produced by a unit load, and the operating load, i.e., the intensity of the load during the operation of the machine.

[0028] Therefore, information representing noise and vibration levels originating from electromagnetic forces includes the operating point, i.e., the noise and vibration levels as a function of the combination of torque and velocity, which makes it possible to identify the noise-generating operating point. Based on this information, it is possible to adapt the control of the electromechanical system to avoid maximum vibration and minimize the risk of noise and failure.

[0029] The applicant therefore argues that, thanks to the present invention, the determination of noise and vibration levels originating from the magnetic field of an electromechanical device is simplified by reducing computation time by performing calculations only on a reduced number of nodes of eigenmodes and load cases, thereby enabling the effective integration of electromagnetic vibration analysis into the electromechanical device design process.

[0030] In one advantageous embodiment of the present invention, this method further includes displaying information belonging to an information set via a human-machine interface, wherein the information set is • Information representing noise and vibration levels, • Information representing load cases and a subset of significant eigenmodes, • Information representing a set of frequency response functions and Includes.

[0031] Here, it will be understood that the display of the information to be represented corresponds to a rendering, preferably a visual or graphic rendering, of the noise and vibration levels determined at the time the method is performed, or to other relevant elements that assist in the design process of the electromechanical device. Of course, such a display depends on the determined information being represented, in particular its level of detail. The method according to the present invention makes it possible to estimate, for example, in a global manner or depending on a determined point or surface, the overall level of noise or vibration generated by the machine, or otherwise according to the operating level determined at the time the method is performed, from the case of the mode and / or load under consideration. According to another modification, the method according to the present invention makes it possible to estimate coefficients representing the correspondence between a load case and the eigenmodes of a subset of the load case and eigenmodes, for example, via projections as described below. The display then corresponds to, for example, a display of a set of projections between the load case and the eigenmodes, from which the load case and subset of eigenmodes are determined. It will be further understood that the method may be configured to display various quantities or functions determined at the time the method is performed, in particular frequency response functions associated with a plurality of load cases.

[0032] In a particular embodiment, the method further includes receiving information representing a set of magnetic loads associated with a machine, and obtaining first data corresponds to determining a set of load cases associated with the machine from the set of magnetic loads.

[0033] Here, it is understood that this method determines the set of load cases by following the principle of decomposition based on mathematical foundations, which is applied to the set of magnetic loads. This decomposition corresponds to, for example, Fourier series decomposition, or other mathematical foundations known to those skilled in the art.

[0034] The set of magnetic loads is defined, for example, by a set of analytical equations relating to the structure of forces, which characterize the frequencies and wavenumbers of the rotor and stator loads depending on the type of electromachine and its failure conditions.

[0035] In another example, information representing a set of magnetic loads is: • Information representing the machine's status lot number, • Information representing the number of pole pairs in the machine, • Information representing the number of phases of the machine and Includes.

[0036] It will be understood that such information corresponds to discrete design parameters of electromechanical systems, from which analytical equations for spectral support of loads can be established.

[0037] According to the alternative modification, the acquisition of the first data item corresponds to the direct reception of a set of load cases, which is analytically determined separately from the execution of this method.

[0038] In an additional embodiment, the method further includes receiving information representing a mechanical structure, the acquisition of second data corresponding to the determination of a set of intrinsic modes from the structure.

[0039] Those skilled in the art will understand that the determination of all eigenmodes from the structure is performed analytically, for example, by modeling the stator by an equivalent cylinder, or more precisely, by using a beam model in which the teeth and yokes of the stator are modeled as beam elements. The information representing the structure of the machine corresponds, for example, to a model of the machine, or a set of parameters representing the machine that makes it possible to model it.

[0040] According to other forms of modification, the set of eigenmodes is received by this method and determined separately from its execution by a method known to those skilled in the art.

[0041] The set of eigenmodes is determined in this case, for example, by calculations using mechanical finite elements, i.e., by solving the eigenvalue problem from the stiffness and mass matrices of the machine, or otherwise measured through experimental modal analysis.

[0042] In an additional embodiment, this method, • Determine a set of projections between load cases and eigenmodes, where each projection in the set is associated with a load case and an eigenmode. • Each projection in the set of projections is compared to a threshold, and the load cases and a subset of significant eigenmodes are determined as a function of the comparison results. Includes.

[0043] In other words, each significant combination of a load case and an eigenmode is identified when the projection of the load case and eigenmode exceeds a threshold. The load case and eigenmode can be represented, for example, as representative vectors, and each projection corresponds to the scalar product of the two vectors.

[0044] Therefore, it is understood that projections exceeding the threshold here correspond to combinations of similarly shaped load cases and specific modes, i.e., excitations that enter a determined structural mode and spatial resonance.

[0045] Comparing each projection in a set of projections to a threshold allows, for example, the formation of a subset of significant projections, and consequently, a subset of loading cases and significant eigenmodes.

[0046] In yet another modified form, the calculation of the set of projections allows for the identification of the mode with the shape closest to this force, i.e., the mode that has the highest projection with the load case, for each force, for example, for each load case with wavenumber r=0.

[0047] In yet another embodiment, the method further includes determining a set of resonant velocities from a load case and a subset of significant eigenmodes, where each resonant velocity is associated with an eigenmode in the subset, and a first set of operating points is associated with the set of resonant velocities.

[0048] Here, it is understood that determining the load cases and a subset of significant eigenmodes allows for determining one or more speeds at which combinations of load cases and eigenmodes enter resonance. Each eigenmode is associated, for example, with a specific frequency or pulsation, from which the resonance speed can be determined, for example, via the analytical equations described above.

[0049] The association of a first set of operating points with resonant velocities, i.e., the association by including operating points where velocities correspond to resonant velocities, makes it possible to ensure that calculations are performed with respect to the velocities that produce the greatest noise and vibration, and thus ensure accurate calculations. The first set of operating points may, for example, be expanded to include each identified resonant velocity and / or be limited to only the operating points associated with the identified resonant velocities in order to increase the accuracy of the calculations and / or to minimize calculation time.

[0050] In another embodiment that may be combined with the preceding modes, the method further includes determining a set of cross-projection coefficients between load cases, each cross-projection coefficient associated with a combination of two load cases from the set of load cases, and information representing noise and vibration levels originating from electromagnetic forces is further determined as a function of the set of cross-projection coefficients.

[0051] The applicant proposes that the use of cross-projection coefficients allows for obtaining multiple independent coefficients of the operating load that relate to the representation of the mean square vibration velocity of the envelope, representing the overall noise level, and thus limiting calculations at the level of determining information representing noise and vibration levels originating from electromagnetic forces, i.e., simplifying the matching of response functions and operating loads. Thus, determining a set of cross-projection coefficients allows for a reduction in the total number of calculations at variable speeds and facilitates the handling of a large number of operating points. The cross-projection coefficients correspond to the scalar product between vectors representing load cases, for example, the set of projections described above. The cross-projection coefficients are determined, for example, advantageously only for load cases of a subset of load cases and eigenmodes described above, or more generally, only for load cases considered in determining noise and vibration levels originating from electromagnetic forces.

[0052] In yet another embodiment, the method further comprises obtaining a sixth set of data representing a set of emissivity, each emissivity associated with one of the set of eigenmodes, and information representing noise and vibration levels originating from electromagnetic forces is further determined as a function of the sixth set of data.

[0053] The applicant proposes that the use of emissivity associated with each eigenmode allows for the refinement of calculations, particularly power and sound pressure calculations, i.e., information representing noise and vibration levels. Thus, the accuracy of the results obtained is improved, especially in low-frequency situations. In yet another example, emissivity is used only in situations with excitation frequencies below a given threshold.

[0054] As mentioned above, the set of emissivity is obtained only for eigenmodes that belong to a subset of cases, such as the load case and the significant eigenmode case.

[0055] Preferably, the method further includes receiving information representing the mechanical structure, and obtaining a sixth data item corresponds to determining a set of emissivity from the structure.

[0056] The applicant suggests that the set of emissivity can be determined analytically during the execution of the method, for example, by modeling the stator as an equivalent cylinder.

[0057] Those skilled in the art will also understand that a set of emissivity can be calculated from the mode deformation of each eigenmode using acoustic finite elements.

[0058] The set of emissivity is determined, for example, in parallel with the set of eigenmodes, either directly received, or in parallel with the determination of the eigenmodes, or at a later time after the eigenmodes have been reduced to a subset, based on the same structural information as the eigenmodes.

[0059] In one embodiment, the set of associated nodes includes a first subset of nodes to which magnetic forces are applied on the rotor and stator, a second subset of nodes that generate acoustic noise radiation, and a third subset of isolation interface nodes.

[0060] The applicant proposes that these three subsets correspond to important nodes for the calculation, and that the set of relevant nodes is determined, for example, by identifying and grouping these three subsets. Furthermore, it is understood that the set of relevant nodes may be determined in other ways according to the requirements and the knowledge of those skilled in the art, taking into account nodes whose behavior is important for the calculation of vibrations.

[0061] In a particular embodiment, all frequency response functions include a set of response functions for each load case and, optionally, for each eigenmode from a subset of load cases and significant eigenmodes, and information representing noise and vibration levels originating from the electromagnetic forces of the machine is determined separately for each load case and, optionally, for each eigenmode.

[0062] The applicant hereby proposes that the set of frequency response functions corresponds in the mode expansion performed by this method to a linear combination, for example, a finite sum of the responses for each load case and for each eigenmode. Thus, this design makes it possible to separately calculate the response for each load case, or otherwise the response for each eigenmode for each load case, thereby making it possible to determine and identify the noise and vibration levels that are specifically generated by each load case and, optionally, by each eigenmode, and then the total noise level generated by their combination.

[0063] This combination provides a more detailed analysis of noise sources in particular. For each operating point, the user can identify the natural modes of the load case and / or vibration generator, and consequently adapt the electromechanical design to specifically dampen them. Thus, the user can understand what types of forces excite what types of modes, and thus reduce noise and vibration by, for example, adapting the design of the machine's magnetic circuit, or by acting on the structure by shifting specific natural frequencies.

[0064] In additional embodiments, the set of frequency response functions includes a set of acoustic frequency response functions.

[0065] In other words, the frequency response function corresponds to the sound pressure response under the effect of a given load, e.g., a unit load. The frequency response function is then calculated in the acoustic domain.

[0066] In another embodiment, the set of frequency response functions includes a set of vibration frequency response functions.

[0067] In other words, the frequency response function corresponds to the vibration response under the effect of a given load.

[0068] Of course, it is further understood that the determination of information representing noise and vibration levels originating from the electromagnetic forces of a machine is performed as a function of the determined frequency response function. In the case of an acoustic frequency response function, the information representing noise and vibration levels corresponds, for example, to the sound pressure field under the effect of operating excitation. The acoustic frequency response function is determined, for example, on an acoustic mesh and again restricted to a set of nodes relevant to those skilled in the art (e.g., the points surrounding the machine for calculating the acoustic output according to current standards). Conversely, in the case of a vibration frequency response function, the information representing noise and vibration levels corresponds, for example, to the mean square vibration associated with at least one part of the machine.

[0069] It is also possible to determine a set of frequency response functions that includes both a set of acoustic frequency response functions and a set of vibration frequency response functions. This design corresponds to acoustic calculations separated from radiation calculations, for example, by combined mechanical-acoustic calculations, or otherwise by combining them with the modified forms described above, where radiation is combined with vibration frequency response functions to obtain a set of acoustic frequency response functions.

[0070] In an additional embodiment, the method further includes receiving information representing a second set of operating points of a machine, and obtaining a first set of operating points includes processing the second set of operating points.

[0071] Here, the second set of operating points corresponds to the set of points provided for the execution of the method, and it is understood that the generation of the first set of operating points allows for the completion and / or reduction of the number and properties of the operating points, for example, by associating the operating points with the resonant velocities determined above, or by reducing the number of operating points and associated calculations. The determination of additional operating points is performed, for example, by interpolation or extrapolation from the second set of operating points.

[0072] In one embodiment, which may be combined with the previous embodiment, the set of magnetic states is obtained from a first set of operating points.

[0073] Here, the magnetic state is understood to correspond to the magnetic field within the machine associated with the operating point. The magnetic state of the machine can be calculated by several methods, such as the magnetic finite element method, the permeance or magnetomotive force method, the reluctance network, or otherwise by an equivalent electrical circuit. This magnetic state allows for the determination of the operating load associated with the operating point, for example, according to the methods described above for Maxwell's tensor or virtual work.

[0074] In certain embodiments, the method includes receiving information representing the magnetic state, for example, directly receiving a fifth data, or otherwise receiving the distribution of magnetic flux in the air gap, from which the method determines the magnetic force torsor on the stator teeth, for example, by the Maxwell tensor method.

[0075] Over a specific operating range, the amplitude of a magnetic load may be known to be constant or variable. Therefore, determining the set of magnetic states and even the operating point may involve extrapolation, a method that determines the magnetic state of a machine on a single operating point in this range and extrapolates the amplitude and frequency of the excitation harmonics over this operating range, or otherwise interpolates between two known operating points. Of course, the operating point used for interpolation is selected to minimize errors, i.e., inaccuracies, that occur during the interpolation process. Furthermore, the use of interpolation and / or extrapolation over a determined range also allows for minimizing the computational load, and the identification of such a range ensures that the accuracy of the results is not affected. For example, the amplitude of a magnetic load is known to be constant over the operating range of an asynchronous machine with a constant magnetic flux, an open-circuit magnet machine, or a constant current angle.

[0076] According to another modification, the first set of operating points and the set of magnetic states associated with the operating points are both directly imported, and the magnetic states are determined separately from the execution of the method, for example, by magnetic finite elements.

[0077] In yet another embodiment, the method further includes receiving information representing a selection of targets belonging to a set of targets, the set of targets is Root mean square vibration of the machine surface, The root mean square oscillation of at least one node of the machine, The acoustic output is radiated by part or all of the machine, and information representing the noise and vibration levels originating from the electromagnetic force of the machine is further determined as a function of selection, and Includes.

[0078] Herein, it is understood that through the execution of the method according to the present invention, it is possible to obtain multiple pieces of information representing the levels of noise and vibration originating from electromagnetic forces, respectively, and that their use and usefulness may vary depending on the application. In particular, the user may seek to obtain results relating to a limited part of a machine, such as a given surface or point, which are obtained as a result of the vibration behavior of the entire machine. This design makes it possible to precisely determine which levels of noise and vibration should be determined in the course of executing the method, especially for displaying this information in the modified forms described above.

[0079] According to a second aspect, the present invention relates to a device for determining noise and vibration levels originating from electromagnetic forces of an electric motor machine, the device comprising a memory associated with a processor configured to perform steps of the method according to a first aspect of the present invention.

[0080] According to a third aspect, the present invention relates to a computer program that includes instructions for performing a method according to a first aspect of the present invention, in particular when these instructions are executed by at least one processor.

[0081] According to a fourth aspect, the present invention relates to a computer-readable storage medium on which a computer program containing instructions for performing steps of a method according to a first aspect of the present invention is recorded. On the one hand, the recording medium can be any entity or device capable of storing a program. For example, the medium may include storage means such as ROM memory, CD-ROM or microelectronic circuit type ROM memory, or otherwise magnetic recording means or hard disk.

[0082] Furthermore, this recording medium may also be a transmittable medium such as an electrical or optical signal, which can be transmitted via electrical or optical cables, by conventional communication or wireless transmission, or by a self-directional laser beam or other means. The computer program according to the present invention may be downloaded from an internet-type network in particular.

[0083] Alternatively, the recording medium may be an integrated circuit containing a computer program, which is adapted to perform the method described herein or to be used in performing the method described herein.

[0084] According to a fifth aspect, the present invention relates to the use of a method according to a first aspect of the present invention for designing an electric motor machine. Here, the design of an electric motor machine involves the production of multiple prototypes or models of the machine, and it is understood that it is advantageous to determine the magnetic behavior (e.g., torque, losses) and vibroacoustic behavior early in order to identify and correct any defects, particularly by adapting the magnetic excitation and / or physical structure, by minimizing investment and manufacturing costs.

[0085] Therefore, the method according to the present invention enables rapid implementation, which allows for the initiation of sensitivity and optimization studies, i.e., the integration of methods at the design stage, on an industrial scale, for electric motor machines.

[0086] Therefore, based on the above-mentioned distinct functional and structural technical features, the applicant proposes a method and device for determining noise and vibration levels originating from the electromagnetic force of an electric motor machine, enabling a significant reduction in computation time and integration into industrial methods for the design and / or prototyping of electric motor machines.

[0087] Other features and advantages of the present invention will become apparent from the following description of certain non-limiting exemplary embodiments of the invention, with reference to the attached Figures 1 to 6. [Brief explanation of the drawing]

[0088] [Figure 1] This figure illustrates the structure and mechanical mesh of an electric motor machine according to a specific, non-limiting exemplary embodiment of the present invention. [Figure 2] This figure schematically illustrates a device configured to determine the noise and vibration levels originating from the electromagnetic force of the machine in Figure 1, according to a specific, non-limiting exemplary embodiment of the present invention. [Figure 3] This is a flowchart of various steps of a method for determining noise and vibration levels originating from electromagnetic forces in the machine shown in Figure 1, according to a specific, non-limiting exemplary embodiment of the present invention. [Figure 4] This figure illustrates a first graph showing the noise and vibration levels originating from the electromagnetic force of the machine in Figure 1, as determined by the method shown in Figure 3. [Figure 5] This figure illustrates a second graph showing the noise and vibration levels originating from the electromagnetic force of the machine in Figure 1, as determined by the method shown in Figure 3. [Figure 6] This figure illustrates a third graph showing the noise and vibration levels originating from the electromagnetic force of the machine in Figure 1, as determined by the method shown in Figure 3. [Modes for carrying out the invention]

[0089] Methods and devices for determining noise and vibration levels originating from the electromagnetic force of electric motor machinery are described below with reference to Figures 1 to 6. Throughout the following description, the same elements are identified by the same reference symbols.

[0090] As stated in the preamble to this explanation, current solutions for determining noise and vibration levels originating from electromagnetic forces rely on general-purpose software that is not suited to this particular task, has considerably long computation times, and is unsuitable for industrial needs.

[0091] One of the objectives of the present invention is to propose the determination of noise and vibration levels originating from electromagnetic forces, whose operation is adapted to integration in the design of electromechanical devices, particularly in the study of sensitivity and optimization.

[0092] This is made possible in the example described below, in which the method according to the present invention is used in the design phase of an electromechanical device.

[0093] Herein, it will be understood that this embodiment is not limiting, and the method according to the present invention can be incorporated into various different stages involving vibration analysis of electric motor machines.

[0094] In the example shown in Figure 1, machine 1 includes an electric motor comprising a rotor 11 and a stator 12 separated by an air gap 13. Machine 1 corresponds, for example, to a model of an electromechanical device in the design stage, or to a physical prototype whose vibration behavior should be investigated in detail to more accurately identify the source of vibrations. Machine 1 corresponds, for example, to a synchronous machine, an asynchronous machine, or a variable reluctance machine. Of course, in other examples, machine 1 may include multiple rotors 11 and / or multiple stators 12.

[0095] A rotating electromachine generally consists of two main components: a rotor 11 and a stator 12, connected by bearings. An air gap 13 represents the space between the rotor 11 and the stator 12, and the electromechanical transformation takes place within this air gap. An electromachine may include several rotors and several stators, but this does not affect the method described, as it is only the number of cases of magnetic load. The stator 12 is a fixed component made of ferromagnetic material and includes parts called stator rods 12a, 12b, and 12c, which are filled with windings. These windings are connected to a power source that can supply power to the windings of the stator 12 with so-called stator currents. These stator currents cause magnetic field rotation within the air gap 13 of the machine 1.

[0096] The rotor 11 is an elongated component that is made in part from a ferromagnetic material and can rotate around its own longitudinal axis, for example, around the shaft 15.

[0097] In the example shown in Figure 1, machine 1 corresponds to a synchronous machine equipped with magnets 14, and status rods 12a, 12b, 12c include a first set of notches 12a associated with a first phase, a second set of notches 12b associated with a second phase, and a third set of notches 12c associated with a third phase.

[0098] In another example, machine 1 corresponds to an asynchronous machine. In such an example, the rotor 11 has so-called rotor slots, which are filled with coils through which a current called rotor current passes, induced by fluctuations in the magnetic field generated by the stator 12.

[0099] During the operation of machine 1, i.e., during the operation of the electric motor, the rotor 11 begins to rotate in an attempt to follow the magnetic field generated by the stator 12, in accordance with the Lenz-Faraday law. In an asynchronous machine, the speed of the mechanical rotation of the rotor 11 is slightly different from the speed of rotation of the stator magnetic field, but in a synchronous machine, the rotor 11 rotates in sync with the magnetic field of the stator 12.

[0100] The electromagnetic forces at the torque source within the air gap 13 are also a source of vibration and acoustic noise, and these forces deform the structure of the rotor 11 and stator 12 and, more generally, propagate throughout the entire physical structure of the machine 1. The vibrations that are generated propagate into the surrounding air and radiate at audible frequencies, becoming a source of discomfort, and on the other hand, cause mechanical fatigue that can lead to damage in applications where the operation of the machine, such as a hydroelectric generator or wind turbine generator, must be guaranteed over a long period of time.

[0101] These electromagnetic forces primarily arise from the interaction between different harmonic groups of magnetic flux (Maxwell's forces), and the harmonics of magnetic flux themselves are derived from the interaction between different so-called magnetic permeances and magnetomotive harmonics.

[0102] Therefore, identifying and determining the source of vibrations originating from electromagnetic forces, or more simply, whether a given machine is likely to generate vibrations, appears to be a complex problem, especially during the preliminary design phase. Even though there are currently combinations of software solutions that enable the estimation of noise originating from electromagnetic forces in a given machine, these are complex and, in particular, time-consuming.

[0103] To propose a solution to this problem, machine 1 is associated with a computer means configured to carry out a method for determining noise and vibration levels originating from electromagnetic forces, for example, the method shown in Figure 3. As illustrated in Figure 2, such a computer means is advantageously grouped together with an electronic device 2, for example, a computer (hereinafter referred to as "computer"). Computer 2 is configured to transmit and receive data, for example, within a communication network. The elements of computer 2 can be incorporated individually or in combination into a single integrated circuit, several integrated circuits, and / or discrete components. Computer 2 can also be produced in the form of an electronic circuit or software (or computer) module, or a combination of an electronic circuit and a software module.

[0104] Computer 2 comprises one (or more) processors configured to execute instructions for performing steps of the method and / or instructions for performing instructions of embedded software within Computer 2. The processors may include integrated memory, input / output interfaces and various circuits known to those skilled in the art. Computer 2 further includes at least one memory corresponding to, for example, volatile and / or non-volatile memory, and / or a memory storage device which may include volatile and / or non-volatile memory, such as EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, magnetic, or optical disk.

[0105] The computer code for embedded software, which includes instructions to be loaded and executed by the processor, is stored, for example, in the memory of computer 2.

[0106] According to one modified form, computer 2 is configured to implement a method for determining noise and vibration levels originating from electromagnetic forces as part of a broader method, for example, a method for designing an electric motor machine, and quantities calculated during the implementation of the method according to the present invention, for example, noise and vibration levels for each acoustic output or load case, and optionally for each eigenmode, are calculated in this example for each iteration of the design method. The method according to the present invention can also be repeatedly performed on a plurality of machines 1 corresponding to different designs to provide a comparison between different designs, according to one embodiment. The method for designing an electric motor machine includes, for example, creating a model of machine 1, and information associated with the model is recorded in the memory 20 of computer 2.

[0107] In the first step 31 of the method for determining noise and vibration levels, the computer 2 obtains first data representing a set of load cases associated with the machine 1, where each load case corresponds to a component of a magnetic load by a mathematical decomposition such as a Fourier series. Preferably, each load case corresponds to a unit load and is characterized by the type of load, the direction of application, the application structure, and the wave number r. For example, the case of a magnetic load corresponds to a radial force on a rotor with spatial frequency r=0.

[0108] The first data item is received, for example, by a beacon unit 22 of computer 2, which communicates with, for example, the human-machine interface 220 of computer 2. Computer 2 forms a multiplex communication network, to which data is transmitted, for example, via a communication network, for example, wireless or wired links. Thus, computer 2 establishes communication between the human-machine interface 220, which acts as a data acquisition peripheral, and the beacon unit 22, enabling data exchange.

[0109] In another example using the modification form described above, the first data is obtained from the memory 20 of computer 2. In both of these cases, the first data corresponds to the input data, and the set of load cases is determined, for example, analytically, separately from the execution of the process.

[0110] According to one modified configuration, computer 2 receives information representing a set of magnetic loads associated with machine 1, for example, via a beacon unit 22 or memory 20. The computer's processor 21 then determines from the set of magnetic loads a set of load cases associated with machine 1.

[0111] Information representing the set of magnetic loads corresponds to a set of analytical equations and / or parameters of these analytical equations, which, for example, allow the frequency and wavenumber of the effective load to be characterized as a function of, for example, the type of machine 1. Such analytical equations are also established based on the discrete design parameters of machine 1.

[0112] According to an exemplary embodiment, an open-circuit permanent magnet machine is an analytical equation

[0113]

number

[0114] It is associated with.

[0115] r is the wavenumber of the load, f is the frequency of the load, and k s and h r f are two relative integers from the Fourier series decomposition of magnetic flux, where f e Z is an electrical frequency proportional to the operating speed, s is the number of slots in the stator 12, and p is the number of pole pairs in the machine. Modulo [Z s The term [ / 2] relates to the wavenumber of the force observed by the teeth of the stator due to the spatial sampling phenomenon.

[0116] For example, in the case of machine 1, the situation is as follows: [Math 3] p=4 and [Math 4] Z s =48

[0117] Machine 1 includes wavenumber excitation. [Math 5] r=0=48-6*8

[0118] and related frequencies. [Math 6] f = -12f e

[0119] Further, the following are also used. [Math 7] h r = -6

[0120] Such excitation occurs on both the stator 12 and the rotor 11 in both the radial and circumferential directions.

[0121] Different analytical expressions are used for other types of machines 1, particularly synchronous machines, asynchronous machines, and variable reluctance machines. Such analytical expressions can also be established from the number of phases q of the machine 1 s and can also be modified to take into account cases of defects, such as eccentricity that can cause a new load case.

[0122] The higher the excitation frequency, the smaller the vibration. Therefore, these analytical expressions also make it possible to limit the research field with respect to both the frequency and the maximum frequency, shortening the calculation time. Knowing the frequency in advance also makes it possible to optimize the temporal sampling of the electromagnetic simulation.

[0123] Therefore, according to one example, the information representing the set of magnetic loads includes information representing the type of machine, and further the design parameters of the machine 1, particularly the parameters Z s , p and q s and a plurality of information representing them.

[0124] In the second step 32, the computer 2 acquires second data representing the set of natural modes of the mechanical structure of the machine 1.

[0125] As in the alternative embodiment described above, the second data is, according to one example, received directly from the beacon unit 22 or the memory 20 of the computer 2. In this case, the second data is determined, for example, by machine finite elements or measured by experimental modal analysis by using an excitation hammer on the physical machine 1.

[0126] In another example, computer 2 receives information representing a mechanical structure, such as a model of machine 1, or parameters representing its structure, such as rotor 11 and / or stator 12, and processor 21 determines a set of eigenmodes from this information. Processor 21 determines the eigenmodes based on the parameters representing stator 12, for example, by modeling stator 12 as an equivalent cylinder, or more accurately by modeling the teeth and yokes of stator 12 as beam elements.

[0127] In each of these exemplary embodiments, the set of eigenmodes of the mechanical structure corresponds to a set of modes characterized by mode deformation, natural frequency, and mode attenuation, respectively.

[0128] In the third step 33, the computer 2, for example, the processor 21, determines a subset of load cases and significant eigenmodes. In other words, the processor 21 determines which load cases and eigenmodes are most likely to contribute to the oscillation. The oscillation arises as a result of resonance between the load cases and eigenmodes, where the subsets of load cases and eigenmodes are understood to correspond to pairs of load cases whose shapes are similar to the eigenmodes, or vice versa.

[0129] According to one modification configuration, the processor 21 determines a set of projections between load cases and eigenmodes. Each load case and each eigenmode is represented, for example, in the form of a vector, and for each combination of load case and eigenmode, the processor 21 calculates the scalar product between the two vectors corresponding to the projection.

[0130] The determination of load cases and subsets of significant eigenmodes is performed, for example, for each combination, by comparing the relevant projection with a threshold, for example, a threshold recorded in the memory 20 of computer 2, or otherwise a threshold corresponding to the input data received by the beacon unit 22. The threshold is determined, for example, to determine the level of precision of the calculation, with higher thresholds allowing for a limit on the number of load cases and significant eigenmodes, and thus limiting the calculations performed.

[0131] Optionally, computer 2 also determines the resonant velocity from the load case and a subset of significant eigenmodes. The resonant velocity is, for example, the electrical frequency f described above. e Corresponds to the electrical frequency f0. Each eigenmode is characterized by its eigenfrequency f0, and machine 1 favorably uses its frequency f as the electrical frequency f0. e Since it is characterized by an analytical equation that characterizes it as a function of, the resonant velocity, i.e., the electrical frequency f associated with the resonance of the eigenmode with the load case e It becomes possible to make a decision.

[0132] According to the example described above, the processor 21 calculates, for example, the projection of the excitation at wavenumber r=0 corresponding to the most important excitation, thereby identifying the mode whose shape is closest to this force. For example, the projection between the mode and the unit force r=0 in the radial direction makes it possible to identify a particular eigenmode, which is called the stator breathing mode. The analytical formula given above is as follows: [Math 8] f0 = 12f e

[0133] And the electrical frequency f associated with the combination between the load case and the intrinsic mode. e The corresponding resonance velocity is then determined from the natural frequency f0 of the respiratory mode.

[0134] In the fourth step 34, computer 2 obtains third data representing a set of relevant nodes associated with the mechanical structure. From this set of relevant nodes, computer 2 calculates a set of frequency response functions by using modal expansion in the fifth step 35. As is known to those skilled in the art, modal expansion is limited in particular to the relevant nodes, as well as a subset of load cases and significant eigenmodes, thereby reducing the main source of computation time and memory usage.

[0135] For example, the general mode expansion formula is given by the following equation.

[0136]

number

[0137] If x is the complex harmonic displacement I restricted to the set of nodes of interest, then ω m ξ is the natural frequency of the intrinsic mode m in units of rad / s, and is the mode attenuation of mode m. m is the mode shape of mode m among the subsets of mode J, F is the excitation force in units of N, and co is the excitation frequency in units of rad / s.

[0138] In other words, the computer determines the set of nodes in machine 1 to which the mode expansion calculation is restricted. The mode expansion is also restricted to the subset determined above, in order to specifically study the responses that can produce resonance.

[0139] According to one advantageous modification, the set of relevant nodes includes a first subset of nodes to which magnetic force is applied to the rotor 11 and stator 12, a second subset of nodes that generate acoustic noise radiation, and a third subset of isolation interface nodes. In other words, these subsets correspond to different criteria that allow for the identification of relevant nodes in order to ensure correct calculations while limiting the total number of nodes. According to another example, the relevant nodes correspond to nodes configured to be located at the level of the tooth heads and at the mounting points of machine 1 in the structure of machine 1.

[0140] Here, it is understood that each frequency response function corresponds to the behavior of the node as a function of the frequency of the electric motor resulting from the interaction of the load case with the eigenmode. These responses correspond to the sound pressure response in the case of the acoustic frequency response function, or to the vibration response, i.e., the deformation of the node, in the case of the vibration frequency response function.

[0141] For example, the outer surface envelope S of machine 1 has a normal vector n e of, surface element dS e The interval [1,N elem The N of index e included in ] elem The individual elements are discretized into a mesh, and point C e In a finite element machine model centered on this, the normal deformation of the element due to mode expansion U n It is given by the following formula.

[0142]

number

[0143] Here, N mode ψ is the total number of eigenmodes considered. m (f) is the mode projection coefficient of mode m, which is defined as follows:

[0144]

number

[0145] F k (f) The case of the loading associated with the projection, and the amplification factor H m It can be expressed as follows using .

[0146]

number

[0147] The applicant argues that, in particular, the direct calculation of the frequency response function by mode expansion is advantageous in reducing computation time when there are many loads to be processed, according to the general formula for mode expansion given above.

[0148] According to a particular modification, the frequency response function is determined separately for each load case and / or each eigenmode. Those skilled in the art will understand that the node's response to a set of load cases and eigenmodes corresponds to a linear combination of the individual responses to each pair of load cases and eigenmodes. Thus, it is possible to calculate the frequency response function for each case of the load with respect to all eigenmodes separately, or to calculate it separately for each combination of load cases and eigenmodes. In particular, the frequency response function can be determined only with respect to the unique combinations of load cases and eigenmodes of the subset determined above, the pre-selection of which corresponds to the combinations that generate oscillations.

[0149] Therefore, for example, node deformation U n This can be calculated separately for each separate excitation, in particular, using the following formula:

[0150]

number

[0151] Here, WFRF i This is the interval [1,N lc Corresponding to the frequency response function related to the case of load i included in ], N lc F is the number of load cases.i This is the complex amplitude for the case of load i.

[0152] Similarly, each frequency response function can be separated according to its eigenmode from the following equation.

[0153]

number

[0154] Here, ψ i,m This is the projection of load case i under mode m.

[0155] In particular, the frequency response function, also known as FRF, makes it possible to determine a response proportional to a given amplitude load, such as a unit load.

[0156] In the sixth step 36, the computer 2 acquires a fourth data item representing a first set of operating points for machine 1. Each operating point corresponds to the torque and speed of machine 1, i.e., the speed at which the engine can operate.

[0157] Similar to the modification forms described above, the fourth data is received, for example, from the beacon unit 22 or from memory 20, or otherwise determined by the processor 21. Computer 2 receives, for example, a second set of operating points, and the processor 21 determines a first set of operating points from it.

[0158] Here, it will be understood that determining a first set of operating points corresponds to determining a given number of operating points sufficient to determine the behavior of machine 1. The number and nature of the operating points naturally depend on operating criteria known to those skilled in the art. For example, it is possible to construct a first set containing 200 operating points.

[0159] In one favorable modification, the first set of operating points is associated with the resonant velocity determined above, thereby ensuring that the calculation of the load case and subset of significant eigenmodes is performed at a velocity that exhibits resonance. In this case, it is understood that the acquisition of the fourth data item is performed following the determination of the load case and subset of significant eigenmodes. In other cases, the acquisition of the fourth data item may be performed at a different time, for example, in parallel with or upstream of the operation described above.

[0160] According to the example above, the first set of operating points is, for example, the electrical frequency f resulting from the breathing mode of the stator 12, where the speed is associated with one or more torque levels. e This includes one or more points corresponding to the same. In the seventh step 37, the computer 2 obtains fifth data representing a set of magnetic states of machine 1. In particular, the computer obtains the distribution and amplitude of the magnetic force within machine 1.

[0161] To reiterate, the acquisition of the fifth data varies depending on the design and the type of input data. In some examples, the computer determines the electromagnetic state of the machine according to the magnetic finite element method, the magnetic permeance / magnetomotive force method, or the magnetic reluctance network method, which may or may not be coupled to an equivalent electrical circuit. Herein, it is understood that one or the other of these methods may be selected by those skilled in the art based on different criteria, in particular according to various compromises between computation time and accuracy. According to yet another modified form, computer 2 directly receives the fifth data, in particular in parallel with the first set of operating points.

[0162] For example, each magnetic state includes a magnetic torsor for each stator tooth, and each torsor includes radial force, circumferential force, and moment.

[0163] Furthermore, each magnetic state in the set of magnetic states is associated with an operating point in the first set of operating points. Of course, obtaining a set of magnetic states also depends on obtaining the first set of operating points.

[0164] In particular, when the processor 21 determines a set of magnetic states associated with a number of operating points, the calculation can be reduced by interpolation or extrapolation of forces, i.e., along a specific operating range, for example, for a fixed torque or velocity, or conversely, for the same torque / velocity ratio. Depending on the operating range considered, the magnetic load may be constant amplitude, in which case the processor 21 determines the magnetic states associated with the operating points and extrapolates them over that range. For example, such extrapolation can be applied to an asynchronous machine 1 with a constant magnetic flux, an open-circuit magnet, or a machine 1 with a constant current angle.

[0165] In other operating ranges, the processor 21 can interpolate the force between two operating points by selecting an operating point that minimizes the error. For example, fluctuations in the current vector are limited between two consecutive operating points.

[0166] In step 38, the computer 2 then determines a set of operating loads from a set of magnetic states.

[0167] In particular, as in the load case, the operating load corresponds to the decomposition of magnetic force and determines the amplitude, for example, in units of N, for each load case at a given operating point.

[0168] Therefore, computer 2 infers a set of working loads from the fifth data, for example, by the Maxwell tensor method. According to another modified form, the fifth data includes the distribution of magnetic fields on the magnetic mesh of machine 1, and computer 2 applies the virtual work method and integrates the torsion of forces by the teeth to infer a set of working loads.

[0169] Therefore, the operating load is the amplitude of the load case determined above, for example, the complex amplitude F mentioned above. iThis makes it possible to determine (f). Finally, in step 39 of the ninth step, the computer determines from the set of operating loads and the set of frequency response functions information representing the noise and vibration levels originating from the electromagnetic force of machine 1.

[0170] Here, it is understood that this decision corresponds to the frequency response function, i.e., the correspondence between the vibration or pressure response in response to a given load and the actual intensity of each load depending on the operating point of machine 1.

[0171] Furthermore, it is understood that this information can be determined in more or less detail according to the steps of this method. In particular, this information can be determined separately for each load case and / or each eigenmode, for example, and the total noise level corresponds to a linear combination of the determined set of information.

[0172] For example, information representing noise and vibration levels originating from electromagnetic forces is determined by the mean square velocity v, which is determined via the following so-called electromagnetic vibration synthesis formula. 2 rms It corresponds to.

[0173]

number

[0174] Here, C i,j This corresponds to the tolerance projection coefficient between the loading cases of indices i and j, and is given by the following equation:

[0175]

number

[0176] Here, φ m,l This corresponds to the projection of the mode shape associated with mode m and 1, as follows:

[0177]

number

[0178] In particular, the tolerance projection coefficient C i,j The mode shape is φ m,l Similar to projection, it is independent of the operating load. According to a favorable modification, computer 2 thus determines a set of tolerance projection coefficients between load cases and calculates information representing noise and vibration levels, such as mean square velocity, as a function of this set of tolerance projection coefficients. In other words, the set of tolerance projection coefficients is stored in the computer's memory 20 to simplify calculations in matching the frequency response function and the operating level of each load.

[0179] Furthermore, the following identity holds true. [Math 17] C i,j =C j,i *

[0180] It is also possible to determine only half of the tolerance projection coefficient. According to another embodiment, noise and vibration levels originating from electromagnetic forces are determined within the acoustic domain, as are the frequency response functions. Computer 2 creates a mesh of machine 1 according to the ISO 3744 standard, for example, and the sound pressure p is given for any point M in the ISO 3744 mesh by the following equation.

[0181]

number

[0182] WFRF ap is the frequency response function in the acoustic domain, and OLC is the operating load.

[0183] In the same example, the acoustic output W of machine 1 is given by the following equation.

[0184]

number

[0185] Here, W0 is 10 -12W is equal to P0, P0 is equal to 20 μPa, S ISO3744 This is the total area of ​​the mesh according to the ISO 3744 standard, N ISO3744 This is the total number of nodes according to the ISO 3744 standard.

[0186] It is further understood that the information representing the required levels of noise and vibration resulting from electromagnetic forces, and the calculation methods used accordingly, may vary depending on the purposes of those skilled in the art. Accordingly, according to certain modifications, computer 2 also receives, for example, information from a beacon unit 22 communicating with a human-machine interface 220, representing the selection of targets belonging to a set of targets.

[0187] A set of targets is, for example, The root mean square vibration of the surface of machine 1, The root mean square oscillation of at least one node of machine 1, The acoustic output radiated by part or all of machine 1 and Includes.

[0188] Information representing noise and vibration levels originating from electromagnetic forces is determined as a function of the choices made. Of course, it is understood that other factors may depend on this choice, for example, the calculation of frequency response functions within the acoustic or vibration domain.

[0189] In yet another modified form, computer 2 acquires a sixth set of data representing a set of emissivity, with each emissivity associated with one eigenmode from the set of eigenmodes. Computer 2 directly receives, for example, the set of eigenmodes and the associated set of emissivity, and the emissivity is determined separately from the execution of this method, for example, by acoustic finite elements from the mode deformation of each mode. In another example, the set of emissivity is determined for each eigenmode from a subset of significant eigenmodes and load cases based, for example, information representing the mechanical structure of machine 1. The emissivity is then determined analytically, for example, by modeling the stator 12 with an equivalent cylinder.

[0190] For example, the emissivity c of an eigenmode m of a finite-length cylinder. m It is given by the following formula.

[0191]

number

[0192] Here, k is the wave number, and R c L is the outer radius of the cylinder. st k is the length of the cylinder, z k is the longitudinal wave number, r This is the radial wavenumber.

[0193] In this modified form, information representing noise and vibration levels originating from electromagnetic forces is further determined as a function of a set of emissivity associated with the eigenmodes. The applicant argues that the use of emissivity ensures more accurate results, particularly in low-frequency calculations.

[0194] When emissivity is imposed, the formula for calculating the vibration frequency response can be artificially modified as follows.

[0195]

number

[0196] In this way, the vibrational electromagnetic synthesis equation can be conserved, and at the acoustic output level, the effect of modal emissivity is then considered.

[0197] Therefore, step 39 of the ninth step makes it possible to obtain a set of noise levels as a function of the operating point of machine 1, which makes it possible to identify at least a combination of torque and noise generation speed.

[0198] Optionally, computer 2 proceeds to display information representing noise and vibration levels via a human-machine interface communicating with computer 2. Computer 2 communicates with the human-machine interface 220, for example, via a beacon unit 22 or another dedicated unit, enabling the display of graphic content representing the determined noise and vibration levels.

[0199] The graphic content corresponds to one or more of the graphs exemplified in Figures 4 through 6, for example.

[0200] Therefore, the first graph 4 in Figure 4 corresponds to a spectrogram illustrating the progression of the acoustic output 43 in dB along a curve defined by the frequency 41 in Hz and the rotational speed 42 in revolutions per minute of machine 1. It then becomes possible to estimate the noisiest excitations, such as excitations H24 and H48, corresponding to the ratio between frequency 41 and rotational speed 42.

[0201] The second graph 5 in Figure 5 illustrates the separation of the percentage contribution rates 52 for different load cases in the overall noise level of machine 1 as a function of rotations per minute 51. This second graph 5 makes it possible, for example, to determine which force the noise originates from for a given speed, for example, a circumferential force with wavenumber r=0 on the stator at low speeds, and a radial force with wavenumber r=0 on the stator at high speeds.

[0202] The third graph 6 in Figure 6 represents another spectrogram illustrating the acoustic output level 63 as a function of the order of the eigenmode 61 and the load case 62 for a given velocity. This third graph 6 allows for the separation of the contributions of the load case and the noise modes originating from electricity.

[0203] Other designs may also allow for the separation of contributions from different radiating surfaces of machine 1, for example, by distinguishing between radiation from the flange of machine 1 and radiation from the cylinder head. Thus, having multiple and accurate pieces of information communicated to the user makes it possible to understand which type of force excites which type of mode, thereby reducing vibrations by acting on both the excitation and structure of machine 1, at the time of selection, by, for example, designing different shapes for the magnetic circuit, designing the machine's control, or shifting the machine's natural frequency. This contribution will be seen as enabling work to be carried out in parallel in the electrical and mechanical domains, supporting the design teams in these two aspects.

[0204] In one modified form, computer 2 performs the display of other representable information, for example, as a complement to or replacement for information representing noise and vibration levels. The computer displays graphic content corresponding to the graphics illustrated in Figures 7 and 8.

[0205] The fourth graph 7 in Figure 7 illustrates the set of projections between load case 72 and eigenmode 71. Each point in the fourth graph 7 thus represents the value of the associated scalar product 73, in this case kg, for a combination of load case 72 and a particular mode 71. 0.5 .ms - 2 This illustrates the following. The points in the fourth graph 7 correspond, for example, only to a subset of load cases and combinations of eigenmodes, i.e., to projections greater than the threshold adopted. Such a fourth graph 7 allows for a simple visualization of load cases and significant eigenmode subsets, and even within these subsets, the most important combinations. For example, based on this fourth graph, it is possible to adapt the threshold used to better calibrate the level of detail in the calculations. Advantageously, the fourth graph 7 also illustrates the associated eigenfrequency 74 for each eigenmode 71.

[0206] The fifth graph 8 in Figure 8 illustrates the progression of a set of frequency response functions 82 determined, for example, in m / N units, as a function of frequency 81 in Hz units. This fifth graph 8 makes it possible to visualize the vibration behavior of machine 1 under the effect of an arbitrarily fixed load, such as a unit load, without considering the operating point of machine 1.

[0207] Therefore, it will be understood that the present invention provides a method and device for determining noise and vibration levels originating from electromagnetic forces in electric motor machinery. This method enables faster and significantly simpler calculations, particularly those performed in the field, compared to solutions used in the prior art. Thus, this method enables the integration of electromagnetic vibration analysis into the design phase of electric motor machinery by allowing results to be obtained within a delay time that is suitable for the temporal constraints of the domain, without sacrificing accuracy.

[0208] It will be understood that this decision-making method can be applied to various electric motor machines and may be integrated into broader methods of designing and / or modeling electric motor machines.

[0209] While this detailed description relates to specific exemplary embodiments of the invention, it should be noted that in no case is this description intended to be restrictive to the subject matter of the invention, but rather to eliminate any possible inaccuracies or insufficient interpretation of subsequent claims.

[0210] Of course, the present invention is not limited to the exemplary embodiments described above, but also extends to methods for determining information representing noise originating from electromagnetic forces, which would include secondary steps without departing from the scope of the invention. The same applies to systems and / or devices configured to carry out such methods.

[0211] Furthermore, it should be noted that the reference numerals placed in parentheses within the following claims are not restrictive in any way, and their sole purpose is to improve clarity and understanding of the subsequent claims and the scope of protection sought. [Explanation of symbols]

[0212] 1 machine 2 Computers 4. Graph 1 5. Second graph 6. Third Graph 7. The fourth graph 8. Graph No. 5 11 rotors 12 staters 12a, 12b, 12c Status Lot 13 Air gap 14 Magnets 15 shafts 20 memory 21 processors 22 Beacon Units 41 Frequencies 42 rotation speed 43. Audio output 51 revolutions per minute 52. Contribution Rate 61 Unique Modes 62 Load Cases 63 Audio output level 71 Unique Modes 72 Load Cases 73 Related scalar products 74 Related natural frequencies 81 Frequencies 82 Frequency Response Function 220 Human-Machine Interface

Claims

1. A method for determining noise and vibration levels originating from electromagnetic force of an electric motor machine (1) having a mechanical structure, wherein the machine (1) comprises a rotor (11) and a stator (12), the rotor (11) and the stator (12) are isolated from an air gap, the method is performed by at least one processor, and the method is - Step (31) of obtaining first data representing a set of load cases associated with the machine (1), wherein each load case corresponds to a component of a magnetic load by a mathematical basis, preferably a decomposition in a Fourier series, - A step (32) of obtaining second data representing a set of eigenmodes of the machine structure, - A step (33) of determining a subset of load cases and significant eigenmodes from the set of load cases and the set of eigenmodes, - A step (34) of obtaining third data representing a set of related nodes associated with the machine structure, - A step (35) of calculating a set of frequency response functions by mode expansion restricted to the set of related nodes, and the subset of load cases and significant eigenmodes, - Step (36) of obtaining a fourth data representing a first set of operating points of the machine (1), wherein each operating point is associated with the torque and speed of the machine (1), - Step (37) of obtaining a fifth set of data representing a set of magnetic states of the machine (1), wherein each magnetic state in the set of magnetic states is associated with an operating point, - A step (38) of determining a set of operating loads from the set of magnetic states, - Step (39) of determining information representing noise and vibration levels originating from the electromagnetic force of the machine (1) from the set of operating loads and the set of frequency response functions. Methods that include...

2. The system further includes displaying information belonging to a set of information via a human-machine interface, wherein the set of information is - The information representing the noise and vibration levels, - Information representing the load cases and the subset of significant eigenmodes, - Information representing the aforementioned set of frequency response functions and The method according to claim 1, including the method described in claim 1.

3. The method according to claim 1 or 2, further comprising the step of receiving information representing a set of magnetic loads associated with the machine (1), wherein the step of obtaining the first data (31) corresponds to determining the set of load cases associated with the machine (1) from the set of magnetic loads.

4. The method according to any one of claims 1 to 3, further comprising the step of receiving information representing the mechanical structure, wherein the step of obtaining the second data (32) corresponds to determining the set of eigenmodes from the structure.

5. - A step of determining a set of projections between the load case and the eigenmode, wherein each projection in the set of projections is associated with the load case and the eigenmode, - A step of comparing each projection of the set of projections with a threshold, wherein the subset of loading cases and significant eigenmodes is determined as a function of the result of the comparison (33) The method according to any one of claims 1 to 4, further comprising:

6. The method according to any one of claims 1 to 5, further comprising the step of determining a set of resonant velocities from a load case and a subset of significant eigenmodes, wherein each resonant velocity is associated with an eigenmode of the subset, and the first set of operating points is associated with the set of resonant velocities.

7. The method according to any one of claims 1 to 6, further comprising the step of determining a set of cross projection coefficients between the load cases, each cross projection coefficient being associated with a combination of two load cases from the set of load cases, and the information representing the noise and vibration levels originating from electromagnetic forces being further determined as a function of the set of cross projection coefficients (39).

8. The method according to any one of claims 1 to 7, further comprising the step of obtaining a sixth set of emissivity data, each emissivity being associated with one of the set of eigenmodes, and the information representing the noise and vibration levels originating from electromagnetic forces being further determined as a function of the sixth set of data (39).

9. The method of claim 8, further comprising the step of receiving information representing the mechanical structure, wherein the step of obtaining the sixth data corresponds to determining the set of emissivity from the structure.

10. The method according to any one of claims 1 to 9, wherein the set of related nodes includes a first subset of nodes to which magnetic forces are applied on the rotor (11) and the stator (12), a second subset of nodes that generate acoustic noise radiation, and a third subset of isolation interface nodes.

11. The method according to any one of claims 1 to 10, wherein the set of frequency response functions includes a set of response functions for each load case and, optionally, a set of response functions for each eigenmode from the subset of load cases and significant eigenmodes, and the information representing the noise and vibration levels originating from the electromagnetic force of the machine (1) is determined separately for each load case and, optionally, for each eigenmode (39).

12. The method according to any one of claims 1 to 11, wherein the set of frequency response functions includes a set of acoustic frequency response functions.

13. The method according to any one of claims 1 to 12, wherein the set of frequency response functions includes a set of vibration frequency response functions.

14. The method according to any one of claims 1 to 13, further comprising the step of receiving information representing a second set of operating points of the machine (1), wherein the step of obtaining the first set of operating points (36) includes the step of processing the second set of operating points.

15. The method according to any one of claims 1 to 14, wherein the set of magnetic states is obtained from the first set of operating points (37).

16. The process further includes the step of receiving information representing the selection of a target belonging to a set of targets, wherein the information is - The root mean square vibration of the surface of the machine (1), - Root mean square oscillation of at least one node of the machine (1), The method according to any one of claims 1 to 15, further comprising: an acoustic output radiated by part or all of the machine (1), wherein the information representing the noise level and vibration originating from the electromagnetic force of the machine (1) is further determined as a function of the selection (39).

17. A computer program including instructions, wherein when these instructions are executed by a processor, the instructions include instructions for performing the method described in any one of claims 1 to 16.

18. A computer-readable storage medium on which a computer program is recorded, which includes instructions for performing the steps of the method according to any one of claims 1 to 16.

19. A device (2) for determining noise and vibration levels originating from the electromagnetic force of an electric motor machine, wherein the device (2) comprises a memory (20) associated with at least one processor (21) configured to carry out the method described in any one of claims 1 to 16.

20. Use of the method according to any one of claims 1 to 16 for designing an electric motor machine.

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