Motor high-frequency magnetic field, electromagnetic force and loss calculation method

Abstract

The invention discloses a motor high-frequency magnetic field, electromagnetic force and loss calculation method. The method comprises the steps of calculating a motor armature magnetomotive force according to the number of turns and a slot matrix of a motor in combination with a phase current of the motor at any moment; establishing a motor quasi-static finite element model, and extracting a slot leakage magnetic field generated under fundamental current simulation; simplifying the finite element model, and calculating total slot leakage flux density distribution of a motor armature and a slot leakage magnetic field generated by a permanent magnet; calculating a complex slot leakage magnetic field permeability function of the motor armature by combining the armature magnetomotive force; calculating a motor armature slot leakage magnetic field according to the armature magnetomotive force and the magnetic conductance function; synthesizing the motor armature slot leakage magnetic field and the slot leakage magnetic field generated by the permanent magnet to obtain quasi-static distribution of the leakage magnetic field at the cross section of the motor conductor; solving a two-dimensional eddy current field mathematical model according to the differential equation of the time-harmonic field in combination with the quasi-static distribution result of the leakage magnetic field to obtain the distribution condition of the time-harmonic field magnetic field at the conductor cross section; and calculating the electromagnetic force and loss of the motor according to the distribution condition of the magnetic field of the time-harmonic field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-frequency magnetic field calculation of electric machines, and more particularly relates to a method for calculating high-frequency magnetic field, electromagnetic force and loss of electric machines. BACKGROUND

[0002] Electric machines have been widely used in various fields of social production and life. In recent years, the development concept of miniaturization, light weight and energy saving and environmental protection has been continuously deepened, and various industries have put forward more and more stringent requirements on the indicators such as efficiency and power density of electric machines. As the medium of power transmission, the distribution of electric machine magnetic field has always been concerned, on the one hand for the optimization of electric machine magnetic circuit to improve the torque output capability, on the other hand for the evaluation of conductor alternating current loss and electromagnetic force received by stator and rotor.

[0003] The distribution of electric machine internal magnetic field is closely related to the operating condition. In order to accurately evaluate the electric machine magnetic field and provide an effective tool for high-efficiency electric machine design and optimization, a method for quickly and accurately calculating the high-frequency magnetic field of electric machines is urgently needed. The existing electric machine magnetic field calculation methods mainly include analytical method, finite element method and semi-analytical method. In the analytical method, the electric machine magnetic field is calculated by analytical formula. The analytical method is based on a series of simplifications with high efficiency, but the actual electric machine slot structure is complex and the saturation degree cannot be ignored, which leads to low calculation accuracy of the analytical method and limited use scenarios. The finite element method can well evaluate the saturation of electric machine. The magnetic field results are obtained by accurately modeling the electric machine and dividing the grid for numerical solution. Existing researches have compared the results with experimental tests and proved the effectiveness of the finite element method. However, the simulation time of pure calculation of fundamental wave generated magnetic field is relatively short, but the input armature current usually contains harmonic components related to switching frequency, which is much higher than the fundamental wave. In order to ensure the calculation accuracy, the simulation step needs to be increased and the grid division needs to be refined, which greatly increases the simulation time. The semi-analytical method combines the advantages of analytical method and finite element method, uses finite element to obtain the quasi-static calculation results of magnetic field, and then uses analytical formula to calculate the influence of conductor domain eddy current. However, the existing semi-analytical calculation method simplifies the treatment of high-frequency harmonics too much, and cannot reflect the real magnetic field generated by high-frequency components, and has not fundamentally solved the problem of high-frequency magnetic field calculation. SUMMARY

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for calculating high-frequency magnetic fields, electromagnetic forces, and losses in motors. By combining the advantages of analytical methods and the finite element method, and utilizing a quasi-static finite element model and a time-domain armature current waveform calculation method, it solves the problems of low accuracy in traditional analytical methods and long calculation time in finite element methods. This invention offers higher calculation accuracy, shorter calculation time, and a wider range of applications. Furthermore, by introducing innovative methods such as slot magnetomotive force, slot matrix, and frozen permeability, this invention effectively considers the influence of multiple factors such as rotor magnetic field and magnetic field saturation, enabling rapid and accurate calculation of the permeability function and armature magnetomotive force, significantly shortening calculation time and improving accuracy. The constructed system modules have clear division of labor and efficient collaboration, realizing fully automated calculation from operating condition setting to high-frequency magnetic field distribution. This provides a comprehensive, integrated, and efficient solution for motor analysis and optimization design, promoting the development of motor electromagnetic field calculation technology and contributing to the design and optimization of high-efficiency motors.

[0005] To achieve the above objectives, one aspect of the present invention provides a method for calculating the high-frequency magnetic field, electromagnetic force, and losses of a motor, comprising the following steps:

[0006] S100: Calculate the phase current of the motor at any time based on the motor operating conditions; determine the number of turns and slot matrix of the motor based on the slot pole matching and winding distribution, and calculate the armature magnetomotive force of the motor at any time based on the phase current.

[0007] S200: Establish a quasi-static finite element model of the motor, and use the quasi-static finite element model of the motor to extract the slot leakage magnetic field generated under the fundamental current simulation; establish a quasi-static finite element simulation model of the motor with one-phase single-turn winding excitation, set the permanent magnet material properties to air, and calculate the total slot leakage magnetic flux density distribution of the motor armature; subtract the slot leakage magnetic field generated under the fundamental current simulation from the total slot leakage magnetic flux density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet.

[0008] S300: Combining the armature magnetomotive force of the motor at any time and the total slot leakage magnetic flux density distribution of the motor armature, the complex slot leakage magnetic permeability function of the motor armature is calculated using magnetic field theory and numerical calculation methods.

[0009] S400: Calculate the slot leakage magnetic field caused by the motor armature based on the armature magnetomotive force of the motor at any time and the permeability function of the complex slot leakage magnetic field of the motor armature; combine the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the cross section of the motor conductor;

[0010] S500: For the conductor region, a two-dimensional eddy current field mathematical model is established. After dimensionality reduction, the general solution form of the mathematical model is obtained. Based on the boundary conditions determined by the quasi-static distribution of the leakage magnetic field at the conductor cross section of the motor, the distribution of the harmonic magnetic field at the conductor cross section is obtained by solving.

[0011] S600: Calculate electromagnetic force and conductor AC loss according to the distribution of time-harmonic field magnetic field at the conductor cross section.

[0012] Further, step S100 comprises:

[0013] S101: Set motor operating state parameters to determine the operating condition of the motor; the motor operating state parameters include speed, torque, switching frequency and load type;

[0014] S102: Select the corresponding motor mathematical model to describe the operating characteristics of the motor according to the motor type;

[0015] S103: Calculate the phase current of the motor at any time using the selected motor mathematical model and the determined motor operating state parameters;

[0016] S104: Determine the number of turns and slot matrix of the motor according to the slot-pole matching and winding distribution of the motor;

[0017] S105: Calculate the armature magnetic motive force of the motor at any time by combining the calculated phase current, the determined number of turns of the motor and the constructed slot matrix.

[0018] Further, the phase current of the motor at any time in step S103 is calculated by formula (1):

[0019] I A，t =L′ -1 (u A -e A ) (1)

[0020] Where I A，t is the phase current of the motor at any time; L' is the equivalent impedance matrix, including resistance, inductance, step information, u A is the A-phase voltage, and e A is the A-phase counter electromotive force.

[0021] Further, the armature magnetic motive force f of the motor at any time in step S105 is calculated by formula (3):

[0022] f=I A，t ·M slot ·N (3)

[0023] Where I A，t is the phase current of the motor at any time; M slot is the slot matrix of the motor; and N is the number of turns of the motor.

[0024] Further, step S200 comprises:

[0025] S201: A quasi-static finite element model of the motor is established, Fourier transform is performed on motor phase current data when the motor is running, and current harmonic fundamental amplitude and phase are extracted; the fundamental current is taken as input, quasi-static finite element simulation is performed, the magnetic field distribution of the motor under the action of the fundamental current is simulated, the slot leakage magnetic field generated under the simulation of the fundamental current is extracted, and the magnetic permeability distribution at this time is recorded, and the magnetic permeability is frozen;

[0026] S202: A quasi-static finite element simulation model of the motor excited by one turn winding of one phase is established; in the model, the magnetic permeability obtained in step S201 is kept unchanged, the permanent magnet material property is set to air, a constant current with an amplitude of 1 is applied in the conductor, simulation calculation is performed, and the leakage flux density distribution in each slot of the stator is obtained; the leakage flux densities of the slots of the same phase are superimposed to obtain the total slot leakage flux density generated by the phase;

[0027] S203: According to the current amplitude of the three-phase winding of the motor and the symmetry relationship of the magnetic circuit, the slot leakage flux density distributions of the remaining two phases are derived, and the slot leakage flux densities of the three phases are vector superimposed to obtain the total slot leakage flux density distribution of the motor armature;

[0028] S204: The slot leakage magnetic field generated by the permanent magnet is obtained by subtracting the total slot leakage flux density distribution of the motor armature from the slot leakage magnetic field generated under the simulation of the fundamental current.

[0029] Further, the slot leakage magnetic field caused by the motor armature in step S400 is calculated by formula (5):

[0030]

[0031] Wherein, f is the armature magnetic motive force of the motor at any time; is the complex slot leakage magnetic field permeability function of the motor armature;

[0032] The leakage magnetic field at the conductor cross section of the motor in step S400 is represented by formula (7):

[0033]

[0034] Wherein, is the slot leakage magnetic field synthesis flux density at the conductor cross section of the motor; is the slot leakage magnetic field generated by the permanent magnet; is the slot leakage magnetic field caused by the motor armature.

[0035] Further, step S500 includes:

[0036] S501: According to Maxwell's equations, a two-dimensional time differential equation of the eddy current field is established, the dimension is reduced by using the infinitesimal method, and the general solution form of the two-dimensional time differential equation is obtained;

[0037] ​S502: obtaining boundary conditions of two-dimensional time differential equation according to conductor cross-section quasi-static magnetic field distribution;

[0038] S503: obtaining conductor cross-section time-harmonic magnetic field distribution by substituting the boundary conditions into the general solution form of the two-dimensional time differential equation.

[0039] Further, the two-dimensional time differential equation of the eddy current field in step S501 is:

[0040]

[0041] wherein, respectively represent sinusoidal varying magnetic field and electric field, units are ampere per meter and volt per meter respectively; represents the curl of the magnetic field ; represents the curl of the electric field ; σ is the conductivity of the wire, unit is siemens per meter; represents the induced electric field generated by the time-varying magnetic field; -j is the negative imaginary unit; ω is the angular velocity of the magnetic field rotation, unit is radian per second; μ0 is the vacuum permeability of the wire, unit is henry per meter;

[0042] The general solution form of the two-dimensional time differential equation is shown by formula (12):

[0043]

[0044] wherein, represents the component of the magnetic field in the x direction; represents the component of the magnetic field in the y direction; A1, A2 are integral constants, determined by the boundary conditions; these constants are used to fit the solution of a specific problem to meet specific physical conditions or boundary conditions; e -γy is an exponential function, representing the attenuation of the magnetic field intensity in the y direction; e γy is an exponential function, representing the growth of the magnetic field intensity in the y direction; e -γx is an exponential function, representing the attenuation of the magnetic field intensity in the x direction; e γx is an exponential function, representing the growth of the magnetic field intensity in the x direction;

[0045] Further, the boundary conditions of the two-dimensional time differential equation in step S502 include:

[0046] The tangential magnetic density is continuous at the surface of the conductor, and the normal current density is continuous;

[0047] At the conductor boundary, the magnetic field intensity should be zero;

[0048] Inside the conductor, the magnetic field distribution under the time-harmonic electromagnetic field satisfies the distribution form in formula (14):

[0049]

[0050] wherein, represents the magnetic field intensity a function varying with positions x and y; represents the magnetic field intensity a function varying with positions x and y; represents the magnetic field intensity a function varying with x; represents the magnetic field intensity a function varying with y; γ is a skin effect coefficient, i.e., a propagation constant; a and b are geometric sizes of the conductor in x and y directions respectively; ch is a hyperbolic cosine function; represents the magnetic field intensity a function varying with x; represents the magnetic field intensity a function varying with y;

[0051] Step S503 comprises: substituting the boundary condition into the general solution form formula (12) of the two-dimensional time differential equation, solving integral constants A1 and A2, and thus obtaining a special solution satisfying the boundary condition, i.e., the distribution of the time-harmonic magnetic field of the conductor section.

[0052] The second aspect of the application provides a motor high-frequency magnetic field, electromagnetic force and loss calculation system for realizing the motor high-frequency magnetic field, electromagnetic force and loss calculation method, comprising:

[0053] The armature magnetic motive force calculation module is used for determining the operation condition of the motor, calculating the phase current of the motor at any time according to the operation condition of the motor, determining the number of turns and slot matrix of the motor according to the slot-pole matching and winding distribution of the motor, and calculating the armature magnetic motive force of the motor at any time in combination with the phase current.

[0054] The finite element modeling and slot leakage magnetic field calculation module is used for establishing a motor quasi-static finite element model, extracting the slot leakage magnetic field generated under the fundamental current simulation by using the motor quasi-static finite element model, establishing a motor quasi-static finite element simulation model excited by a single-turn winding of one phase, setting the permanent magnet material property as air, calculating the total slot leakage magnetic density distribution of the motor armature, and subtracting the slot leakage magnetic field generated under the fundamental current simulation from the total slot leakage magnetic density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet.

[0055] The module for calculating the complex permeability function of slot leakage magnetic field is used to calculate the complex permeability function of the motor armature by combining the armature magnetomotive force and the total slot leakage magnetic flux density distribution of the motor armature at any time, using magnetic field theory and numerical calculation methods.

[0056] The slot leakage magnetic field synthesis module is used to calculate the slot leakage magnetic field caused by the motor armature based on the armature magnetomotive force of the motor at any time and the complex slot leakage magnetic field permeability function of the motor armature; and to synthesize the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the cross section of the motor conductor.

[0057] The two-dimensional eddy current field calculation module is used to establish a two-dimensional eddy current field mathematical model. After dimensionality reduction, the general solution form of the mathematical model is obtained. Based on the boundary conditions determined by the quasi-static distribution of the leakage magnetic field at the conductor cross section of the motor, the distribution of the harmonic magnetic field at the conductor cross section is obtained.

[0058] The electromagnetic force and loss calculation module is used to calculate the electromagnetic force and AC loss of the conductor based on the distribution of the time harmonic magnetic field at the conductor cross-section.

[0059] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0060] (1) The method and system for calculating the high-frequency magnetic field, electromagnetic force and loss of motors of the present invention innovatively proposes a semi-analytical calculation method for high-frequency magnetic field. This method breaks through the limitation of the traditional analytical method, which is affected by the complexity of the motor slot structure and the degree of saturation, resulting in low accuracy. At the same time, it avoids the problem that the simple finite element method takes a long time to calculate high-frequency harmonics due to the need to increase the number of simulation steps to refine the mesh. It combines the advantages of analytical method and finite element method, and the calculation accuracy is higher than that of traditional analytical calculation method. Moreover, the calculation time is significantly better than that of simple finite element calculation, providing a more accurate and efficient tool for motor analysis and optimization design.

[0061] (2) The method and system for calculating the high-frequency magnetic field, electromagnetic force and loss of the motor of the present invention considers multiple factors such as rotor magnetic field, magnetic field saturation, slot structure and PWM current harmonics during the calculation process. Compared with the prior art, which does not take these factors into account, the present invention can more comprehensively and realistically reflect the actual distribution of the high-frequency magnetic field inside the motor, further improving the accuracy of the calculation results. This helps to optimize the motor magnetic circuit more accurately, improve the torque output capability, and more accurately evaluate the conductor AC loss and the electromagnetic force on the stator and rotor.

[0062] (3) The motor high-frequency magnetic field, electromagnetic force and loss calculation method and system of the present application provides a method for calculating the armature current waveform based on the three-phase coordinate system using the input voltage waveform in the time domain, adopts the backward Euler method to simplify the differential term to construct a linear equation set, and reduces the number of equations by means of the symmetry of the three-phase current, and then quickly solves it by direct matrix inversion, which gets rid of the dependence on the control system simulation, solves the problems of complex and time-consuming current harmonic calculation, greatly shortens the calculation time of the armature current waveform, and further provides more efficient basic data support for subsequent magnetic field calculation.

[0063] (4) The motor high-frequency magnetic field, electromagnetic force and loss calculation method and system of the present application proposes a motor slot leakage magnetic guide calculation method based on quasi-static finite element, which can quickly calculate the magnetic guide function of the motor under any structure and current frequency by constructing a magnetic resistance calculation finite element simulation model under different excitations through the method of freezing magnetic permeability, effectively solving the complex problem of high-frequency magnetic guide calculation, improving the overall efficiency of magnetic field calculation, and making it possible to quickly evaluate and analyze the magnetic field of the motor under various operating conditions.

[0064] (5) The motor high-frequency magnetic field, electromagnetic force and loss calculation method and system of the present application introduces slot magnetic motive force and slot matrix for calculating the armature magnetic motive force of the motor under any current excitation, which greatly shortens the calculation time of the armature magnetic motive force considering high-frequency current harmonics, and at the same time improves the calculation accuracy, providing efficient and accurate magnetic motive force data for subsequent accurate calculation of motor high-frequency magnetic field.

[0065] (6) The motor high-frequency magnetic field, electromagnetic force and loss calculation system of the present application integrates multiple mutually cooperating modules, including an armature magnetic motive force calculation module, a finite element modeling and slot leakage magnetic field calculation module, a slot leakage magnetic complex magnetic guide function calculation module, a slot leakage magnetic field synthesis module, and a two-dimensional eddy current field calculation module, etc. These modules work together efficiently to realize the whole process automation calculation from motor operating condition parameter setting, phase current calculation, armature magnetic motive force determination, to finite element modeling, magnetic guide function calculation, slot leakage magnetic field synthesis, and then to two-dimensional eddy current field analysis, and build a complete and efficient motor high-frequency magnetic field, electromagnetic force and loss calculation platform, which provides a comprehensive and integrated solution for electromagnetic analysis, optimal design and related performance research of the motor, effectively improving the overall efficiency and quality of motor design and research and development. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 It is a flowchart of a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0067] Figure 2A schematic diagram of a process for obtaining the distribution of the conductor cross-section harmonic magnetic field in a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0068] Figure 3 A schematic diagram of a process for calculating the armature magnetic motive force of the motor at any time in a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0069] Figure 4 A schematic diagram of a process for calculating the complex slot leakage magnetic field permeability function of the motor armature in a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0070] Figure 5 A schematic diagram of a process for calculating the quasi-static leakage magnetic field at the conductor cross-section of the motor in a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0071] Figure 6 A schematic diagram of a process for obtaining the conductor cross-section harmonic magnetic field by a two-dimensional eddy current field calculation module in a motor high-frequency magnetic field, electromagnetic force and loss calculation method of an embodiment of the present application;

[0072] Figure 7 A schematic diagram of the structure of a motor high-frequency magnetic field, electromagnetic force and loss calculation system of an embodiment of the present application

[0073] Figure 8 A schematic diagram of the structure of an electronic device of an embodiment of the present application. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0075] When the motor is powered by a PWM (pulse width modulation) frequency converter, the input current contains a series of high-frequency harmonic components related to the switching frequency in addition to the fundamental component. These harmonic frequencies are usually much higher than the fundamental frequency. The "high frequency" in the present application refers to the frequency related to the current harmonic component generated during the operation of the motor, which is much higher than the fundamental frequency.

[0076] As shown in Figures 1-6 The present application provides a motor high-frequency magnetic field, electromagnetic force and loss calculation method, which comprises the following steps:

[0077] S100: calculating phase current of the motor at any time according to the motor operating condition; determining the number of turns and slot matrix of the motor according to the slot-pole matching and winding distribution of the motor, and combining the phase current to calculate the armature magnetic motive force of the motor at any time;

[0078] S200: establishing a motor quasi-static finite element model, extracting the slot leakage magnetic field generated under the fundamental current simulation by using the motor quasi-static finite element model; establishing a motor quasi-static finite element simulation model excited by a single-turn winding of a phase, setting the permanent magnet material property as air, and calculating the total slot leakage flux density distribution of the motor armature; subtracting the slot leakage magnetic field generated under the fundamental current simulation from the total slot leakage flux density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet;

[0079] S300: combining the armature magnetic motive force of the motor at any time and the total slot leakage flux density distribution of the motor armature, and calculating the complex slot leakage magnetic field permeance function of the motor armature by using the magnetic field theory and numerical calculation method;

[0080] S400: calculating the slot leakage magnetic field caused by the motor armature according to the armature magnetic motive force of the motor at any time and the complex slot leakage magnetic field permeance function of the motor armature; synthesizing the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the conductor cross section of the motor;

[0081] S500: for the conductor region, establishing a two-dimensional eddy current field mathematical model, obtaining the general solution form of the mathematical model after dimension reduction processing, determining the boundary condition based on the quasi-static distribution result of the leakage magnetic field at the conductor cross section of the motor, and solving to obtain the distribution of the time-harmonic magnetic field at the conductor cross section;

[0082] S600: calculating the electromagnetic force and loss of the motor according to the distribution of the time-harmonic magnetic field at the conductor cross section.

[0083] The motor magnetic field under various operating conditions can be quickly evaluated and analyzed, and the results can be used for subsequent electromagnetic force calculation and conductor alternating current loss calculation.

[0084] Further, step S100 comprises:

[0085] S101: setting motor operating state parameters to determine the operating condition of the motor; the motor operating state parameters include speed, torque, switching frequency and load type, which will affect the magnetic field distribution and current condition inside the motor;

[0086] S102: selecting a corresponding motor mathematical model to describe the operating characteristics of the motor according to the type of the motor (such as asynchronous motor, permanent magnet synchronous motor, etc.); the commonly used motor mathematical models include models based on circuit theory and models based on magnetic field theory;

[0087] S103: Using the selected motor mathematical model and the determined motor operating state parameters, calculate the phase current of the motor at any time.

[0088] S104: Determine the number of turns and slot matrix of the motor based on the slot-pole match (i.e., the match between the number of slots and poles) and the winding distribution.

[0089] S105: Combining the calculated phase current, the determined number of motor turns, and the constructed slot matrix, the armature magnetomotive force of the motor at any given time is calculated using the armature magnetomotive force calculation formula.

[0090] Furthermore, the phase current of the motor at any given time in step S103 is calculated using equation (1):

[0091] I A，t =L′ -1 (u A -e A (1)

[0092] Among them, I A，t Let L be the phase current of the motor at any given time; L′ is the equivalent impedance matrix, containing resistance, inductance, and step size information, u A Let e ​​be the voltage of phase A. A The opposite potential of A;

[0093] Furthermore, in step S104, the motor slot matrix is ​​used to describe the conductor distribution within any motor slot and is one of the key parameters for calculating the armature magnetomotive force; the dimension of the slot matrix is ​​m×Q. s Where m is the number of phases of the motor, Q s This represents the number of slots in the motor.

[0094] The rules for establishing the motor slot matrix are as follows: when all conductors in a slot belong to the same phase, the corresponding row and column elements in the slot matrix are set to 1; when conductors in a slot do not belong to the same phase, the corresponding row and column elements in the slot matrix are set to 0.5. Taking a three-phase 126-slot 14-pole integer slot double-layer short-pitch winding as an example, its motor slot matrix can be represented as follows:

[0095]

[0096] Among them, M slot For motor slot matrix;

[0097] Furthermore, in step S105, the armature magnetomotive force f of the motor at any given time is calculated using equation (3):

[0098] f = I A，t ·M slot ·N (3)

[0099] Among them, IA，t is the phase current of the motor at any moment; M is the slot matrix of the motor; N is the number of turns of the motor; slot is the slot matrix of the motor; N is the number of turns of the motor;

[0100] Further, in step S200, a quasi-static finite element model is used to simulate the magnetic field distribution inside the motor. Quasi-static assumption is applied here because in high-frequency magnetic field calculation, although there is a certain dynamic effect, the magnetic field change can be approximately considered to be relatively slow to some extent, thereby simplifying the calculation model, making the calculation amount more controllable, and also facilitating the subsequent analysis of key magnetic field characteristics such as leakage magnetic field. The permanent magnet is another important source of the magnetic field of the motor, and its magnetic field distribution has a significant impact on the performance of the motor; the slot leakage flux density, i.e., the magnetic induction intensity distribution of the leakage flux in the motor slot. The slot leakage flux density reflects the leakage of the motor slot, and is an important content of analyzing the magnetic field distribution of the motor; the complex slot leakage field permeance function of the motor armature is used to describe the permeability characteristics of the armature winding slot leakage, and is an important basis for subsequent calculation of the armature leakage field;

[0101] Further, step S2 comprises:

[0102] S201: Establish a quasi-static finite element model of the motor, Fourier transform the motor phase current data during motor operation, extract the fundamental harmonic current amplitude and phase; take the fundamental harmonic current as input, perform quasi-static finite element simulation, simulate the magnetic field distribution of the motor under the action of the fundamental harmonic current; extract the slot leakage field generated under the simulation of the fundamental harmonic current, record the permeability distribution at this time, and freeze the permeability;

[0103] S202: Construct a simplified model and calculate the leakage flux density, establish a quasi-static finite element simulation model of the motor excited by one-turn winding of one phase; in the model, keep the permeability obtained in step S201 unchanged, set the permanent magnet material property to air to eliminate the influence of the permanent magnet; and apply a constant current with an amplitude of 1 in the conductor, perform simulation calculation, and obtain the leakage flux density distribution in each slot of the stator; superimpose the leakage flux densities of the slots of the same phase to obtain the total slot leakage flux density generated by the phase;

[0104] S203: According to the current amplitude of the three-phase winding of the motor and the symmetry relationship of the magnetic circuit, the slot leakage flux density distributions of the remaining two phases are derived, and the slot leakage flux densities of the three phases are vector superimposed to obtain the total slot leakage flux density distribution of the motor armature;

[0105] S204: Subtract the slot leakage field generated by the permanent magnet from the slot leakage field generated under the simulation of the fundamental harmonic current to obtain the slot leakage field generated by the permanent magnet;

[0106] Further, in the step S201, the influence of high-order harmonics is ignored, and it is assumed that the core saturation degree is mainly determined by the fundamental current; the influence of eddy current on the conductor is ignored, and it is assumed that the current distribution in the conductor is uniform, and the eddy current effect caused by the non-uniform distribution of the current in the conductor is not considered; the fundamental current is taken as the input to perform quasi-static finite element simulation, so as to simulate the magnetic field distribution of the motor under the action of the fundamental current, which means that the current distribution is assumed to be static and not to change with time in the simulation; the slot leakage magnetic field refers to the magnetic field leakage caused by the slot structure of the motor, and the slot leakage magnetic field here is the leakage magnetic field under the joint action of the fundamental current and the permanent magnet; the magnetic permeability is frozen, that is, the magnetic permeability is kept constant in the subsequent simulation and does not change with the magnetic field strength;

[0107] In the step S201, the slot leakage magnetic field distribution generated under the fundamental current simulation is represented by formula (4):

[0108]

[0109] wherein, is the slot leakage magnetic field distribution generated under the fundamental current simulation; i sin is the fundamental current; M slot is the slot matrix of the motor; is the complex slot leakage magnetic field permeability function of the motor armature; is the slot leakage magnetic field generated by the permanent magnet under the fundamental simulation, which can be equivalent to the leakage magnetic field under the actual working condition;

[0110] Further, in the step S202, the motor quasi-static finite element simulation model is a single-layer, single-slot and single-turn motor quasi-static finite element simulation model; the radial and tangential components of the slot leakage magnetic density in each slot of the stator are respectively and Both are 1xQ s dimension complex matrix;

[0111] Further, the step S300 includes:

[0112] By using a numerical calculation method such as the finite element method, the magnetic field distribution in the motor is solved based on the boundary conditions such as the geometric structure, material properties and armature magnetomotive force of the motor, and the slot leakage magnetic density distribution data is obtained;

[0113] Referring to Ohm's law in circuit theory, in the magnetic field theory, the permeability function is analogous to a parameter for describing the relationship between magnetic flux and magnetomotive force;

[0114] If the armature magnetomotive force contains harmonic components, the corresponding slot leakage magnetic density of each harmonic component needs to be calculated, and then the complex slot leakage magnetic field permeability function is obtained, and finally the magnetic permeability functions of the harmonic components are superimposed to obtain the total complex slot leakage magnetic field permeability function;

[0115] The complex slot leakage magnetic field permeability function data calculated are processed and fitted to obtain a concise and accurate expression.

[0116] The complex slot leakage magnetic field permeability function of the motor armature in step S300 is represented by formula (15) to formula (17):

[0117]

[0118] Wherein, λ s is the complex vector of the stator-rotor air gap permeability; s represents the stator-rotor; represents the normal permeability component; represents the tangential permeability component; j is a complex unit; is the normal air gap magnetic density at the center line of the air gap when there are tooth slots; is the tangential air gap magnetic density at the center line of the air gap when there are tooth slots; B n，slotless is the normal air gap magnetic density at the center line of the air gap when there are no tooth slots; B t，slotless is the tangential air gap magnetic density at the center line of the air gap when there are no tooth slots.

[0119] The complex slot leakage magnetic field permeability function of the motor armature in the application is an important parameter in motor analysis, which is related to the electromagnetic design and performance evaluation of the motor. The slot leakage magnetic complex permeability function of the armature can be used to calculate the loss of the motor under the action of alternating current, including copper loss and iron loss; by analyzing the slot leakage magnetic complex permeability function of the armature, the motor design can be optimized, and its operating efficiency can be improved; the slot leakage magnetic complex permeability function of the armature helps to evaluate the thermal effect of the motor during operation, so as to carry out effective thermal management design; through finite element simulation and Fourier analysis and other methods, the specific expression of this function can be obtained, which provides a theoretical basis for the optimization design and performance improvement of the motor.

[0120] The slot leakage magnetic field caused by the motor armature in step S400 is calculated by formula (5):

[0121]

[0122] Wherein, f is the armature magnetic motive force of the motor at any time; is the complex slot leakage magnetic field permeability function of the motor armature;

[0123] The slot leakage magnetic field generated by the permanent magnet in step S400 is calculated by formula (6):

[0124]

[0125] Wherein, is the slot leakage magnetic field generated by the permanent magnet under the fundamental wave simulation;

[0126] The leakage magnetic field at the motor conductor cross section in step S400 is represented by formula (7):

[0127]

[0128] Wherein, is the slot leakage magnetic flux density at the motor conductor cross section;

[0129] The quasi-static distribution of the leakage magnetic field at the motor conductor cross section in step S400 is the basis for high-frequency magnetic field calculation, and provides an initial condition for subsequent analysis of the magnetic field change of the motor in high-frequency operation;

[0130] Further, since the eddy current effect inside the conductor is significant in the high-frequency case, step S500 establishes a two-dimensional eddy current field mathematical model to describe the magnetic field distribution inside the conductor, including the following steps:

[0131] S501: According to Maxwell's equations, a two-dimensional time differential equation of the eddy current field is established, and a micro-element method is used for dimension reduction processing to obtain a general solution form of the two-dimensional time differential equation;

[0132] S502: Obtain the boundary conditions of the two-dimensional time differential equation according to the quasi-static magnetic field distribution of the conductor cross section;

[0133] S503: Substitute the boundary conditions into the general solution form of the two-dimensional time differential equation to obtain the distribution of the time-harmonic magnetic field of the conductor cross section;

[0134] Further, in step S501, since the axial length of the motor is much larger than the radial and tangential dimensions, and the magnetic field changes little in the axial direction, the motor is treated as a two-dimensional problem, and the axial change is ignored. A two-dimensional eddy current field mathematical model is established; it is assumed that the magnetic field in the two-dimensional eddy current field mathematical model mainly distributes in the radial and tangential directions, and is uniformly distributed along the axial direction;

[0135] A cylindrical coordinate system (x, y, z) is used, and the axial symmetry of the motor structure is considered, and the change in the z direction is ignored, which is further simplified as a plane problem, i.e. only the magnetic field distribution in the x and y directions is considered;

[0136] According to Maxwell's equations, ignoring displacement current (because the main concern is the low-frequency eddy current effect), the two-dimensional time differential equation of the eddy current field is obtained as:

[0137]

[0138] Wherein, respectively represent the sinusoidal varying magnetic field and electric field, with units of ampere per meter and volt per meter, respectively; denotes the curl of the magnetic field ; denotes the electric field σ is the conductivity of the wire, in Siemens per meter; Eindis the induced electric field generated by the time-varying magnetic field; -j is the negative imaginary unit; ω is the angular velocity of the magnetic field rotation, in radian per second; μ0is the vacuum permeability of the wire, in Henry per meter;

[0139] According to the formula (8), the differential expression of the eddy current electric field generated by the time-varying magnetic field can be obtained as shown in formula (9):

[0140]

[0141] wherein γ is the skin effect coefficient, i.e. the propagation constant, used to describe the propagation characteristics of electromagnetic waves in a conductive medium, including attenuation and phase change;

[0142] Neglecting the influence of the motor end, the magnetic field distribution of the radial flux motor along the axial direction is approximately the same, and the interaction relationship between the magnetic field and the electric field is described by the two-dimensional equation set in formula (10):

[0143]

[0144] wherein, Bxrepresents the component of the magnetic field in the x direction; Byrepresents the component of the magnetic field in the y direction; n is the harmonic number, indicating the order of the harmonic; represents the second-order partial derivative of the magnetic field intensity in the x direction, representing the rate of change of the magnetic field intensity in the x direction; represents the second-order partial derivative of the magnetic field intensity in the y direction, representing the rate of change of the magnetic field intensity in the y direction; represents the second-order partial derivative of the magnetic field intensity in the x direction, representing the rate of change of the magnetic field intensity in the x direction; represents the second-order partial derivative of the magnetic field intensity in the y direction, representing the rate of change of the magnetic field intensity in the y direction;

[0145] Using the micro-element method, the magnetic field is sequentially subdivided along the x and y directions on the conductor cross-section. When the differential element is small enough, it can be considered that there is no change in the electromagnetic wave during the transmission. At this time, the magnetic field equation in formula (10) can be reduced to the first-order form in formula (11):

[0146]

[0147] wherein, is the partial derivative symbol, representing the rate of change with respect to a certain variable; denotes the magnetic field strength is the second-order rate of change in the y direction; denotes the magnetic field strength is the second-order rate of change in the x direction; denotes the magnetic field strength is a function that varies with position x and y; denotes the magnetic field strength is a function that varies with position x and y;

[0148] The general solution of the two-dimensional time differential equation obtained according to formula (11) is shown in formula (12):

[0149]

[0150] wherein A1 and A2 are integral constants determined by the boundary conditions; these constants are used to fit the solution of a specific problem to meet specific physical conditions or boundary conditions; e -γy is an exponential function, representing the magnetic field strength is the attenuation in the y direction; e γy is an exponential function, representing the magnetic field strength is the growth in the y direction; e -γx is an exponential function, representing the magnetic field strength is the attenuation in the x direction; e γx is an exponential function, representing the magnetic field strength is the growth in the x direction;

[0151] Based on the electromagnetic induction law shown in formula (13), the arithmetic mean equivalent treatment is performed on the non-uniform external magnetic field boundary, and the specific form of formula (13) is as follows:

[0152]

[0153] wherein, is the electric field strength is the line integral along the closed loop L, representing the total electromotive force of the electric field in the closed loop; denotes the mean value of the external magnetic field, and denotes the average value of the magnetic field strength in a specific region S; Φ eddy denotes the magnetic flux generated by the eddy current, and denotes the magnetic flux generated in the conductor due to the eddy current effect;

[0154] Further, in step S502, the boundary conditions include:

[0155] The tangential magnetic density is continuous at the surface of the conductor, and the normal current density is continuous; at the boundary of the conductor, the magnetic field strength should be zero, that is, at the boundary of the conductor, and The value of Bx is zero;

[0156] Further, in step S503, the magnetic field distribution under the time-harmonic electromagnetic field inside the conductor satisfies the distribution form in formula (14):

[0157]

[0158] wherein, represents the magnetic field intensity in the x direction, which is a function of x variation; represents the magnetic field intensity in the y direction, which is a function of y variation; a and b are the geometric dimensions of the conductor in the x and y directions, respectively; ch is the hyperbolic cosine function; represents the magnetic field intensity in the x direction, which is an average value in the specific region S inside the conductor; represents the magnetic field intensity in the y direction, which is an average value in the specific region S inside the conductor; are boundary conditions calculated by the quasi-static magnetic field distribution of the conductor cross section;

[0159] Formula (14) gives the distribution of the magnetic field intensity components and on the conductor cross section; by introducing the hyperbolic cosine function, the formula considers the attenuation characteristics of the magnetic field at the boundary of the conductor, ensuring that the values of the magnetic field at the boundary of the conductor (i.e. and ) are zero, which conforms to the physical reality;

[0160] Further, step S503 includes: substituting the above boundary conditions into the general solution of the two-dimensional time differential equation-formula (12), solving the integral constants A1 and A2, and thus obtaining the particular solution that satisfies the boundary conditions, i.e., the distribution of the time-harmonic magnetic field of the conductor cross section.

[0161] Further, the electromagnetic force calculation in step S600 includes: determining the distribution of the magnetic field intensity and the magnetic induction intensity according to the distribution of the time-harmonic field magnetic field at the conductor cross section; calculating the electromagnetic force in the conductor by using the Lorentz force formula; and integrating the electromagnetic force density on the conductor cross section to obtain the total electromagnetic force on the conductor cross section;

[0162] The loss calculation includes copper loss calculation and iron loss calculation; the copper loss calculation includes: determining the current density according to the current distribution at the conductor cross section; and calculating the copper loss by using Joule's law;

[0163] The iron loss calculation includes:

[0164] According to the magnetic field distribution at the conductor section, the magnetic induction intensity is determined;

[0165] According to the magnetic induction intensity, the hysteresis loss and the eddy current loss are calculated;

[0166] The hysteresis loss and the eddy current loss are summed to obtain the total iron loss.

[0167] The present application evaluates the influence of the electromagnetic force on the motor structure and the operation stability by analyzing the distribution of the electromagnetic force on the conductor section; the total loss of the motor is evaluated by comprehensively considering the copper loss and the iron loss, and then the efficiency of the motor is calculated; finally, the structure and the operation parameters of the motor are optimized according to the calculation results, so as to improve the efficiency and the performance of the motor; the present application can comprehensively and accurately calculate the electromagnetic force and the loss of the motor under high-frequency operation conditions, and provides a scientific basis for the design, optimization and performance evaluation of the motor.

[0168] As shown in Figure 7 The second aspect of the present application provides a motor high-frequency magnetic field, electromagnetic force and loss calculation system, comprising:

[0169] The armature magnetic motive force calculation module is used to determine the operation condition of the motor, calculate the phase current of the motor at any time according to the operation condition of the motor, determine the number of turns and the slot matrix of the motor according to the slot-pole matching and the winding distribution of the motor, and calculate the armature magnetic motive force of the motor at any time in combination with the phase current;

[0170] The finite element modeling and slot leakage magnetic field calculation module is used to establish a quasi-static finite element model of the motor, extract the slot leakage magnetic field generated under the simulation of the fundamental current by using the quasi-static finite element model of the motor, establish a quasi-static finite element simulation model of the motor excited by a single turn of a phase winding, set the permanent magnet material property as air, calculate the total slot leakage flux density distribution of the motor armature, and obtain the slot leakage magnetic field generated by the permanent magnet by subtracting the slot leakage magnetic field generated under the simulation of the fundamental current from the total slot leakage flux density distribution of the motor armature.

[0171] The slot leakage magnetic complex permeance function calculation module is used to calculate the complex slot leakage magnetic field permeance function of the motor armature by using the magnetic field theory and the numerical calculation method in combination with the armature magnetic motive force of the motor at any time and the total slot leakage flux density distribution of the motor armature.

[0172] The slot leakage magnetic field synthesis module is used to calculate the slot leakage magnetic field caused by the motor armature according to the armature magnetic motive force of the motor at any time and the complex slot leakage magnetic field permeance function of the motor armature, and synthesize the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the conductor section of the motor.

[0173] A two-dimensional eddy current field calculation module is configured to establish a two-dimensional eddy current field mathematical model, to obtain a general solution form of the mathematical model after dimension reduction processing, and to solve the distribution of the time-harmonic magnetic field at the conductor cross section based on boundary conditions determined according to the quasi-static distribution of the leakage magnetic field at the conductor cross section.

[0174] An electromagnetic force and loss calculation module is configured to calculate electromagnetic force and conductor alternating current loss according to the distribution of the time-harmonic magnetic field at the conductor cross section.

[0175] Further, the armature magnetic motive force calculation module provides basic motor operating condition data and armature magnetic motive force for the entire system. The phase current, number of turns, slot matrix, and armature magnetic motive force data calculated by the armature magnetic motive force calculation module are used as inputs for subsequent finite element modeling modules, complex slot leakage magnetic field permeance function calculation modules, and other modules for further magnetic field calculation and analysis.

[0176] The finite element modeling and slot leakage magnetic field calculation module receives data such as phase current, armature magnetic motive force, number of turns, and slot matrix from the armature magnetic motive force calculation module, and performs quasi-static finite element modeling and simulation calculation to obtain results such as slot leakage magnetic field under the fundamental current, total slot leakage magnetic density distribution of the armature, and slot leakage magnetic field generated by the permanent magnet. The module provides key magnetic field data for the complex slot leakage magnetic field permeance function calculation module, and the permeability frozen data obtained by the module also provides necessary electromagnetic characteristic parameter references for the subsequent eddy current field calculation module.

[0177] The slot leakage magnetic complex permeance function calculation module receives slot leakage magnetic density distribution data, armature magnetic motive force, and motor geometry and material properties from the finite element modeling and slot leakage magnetic field calculation module, calculates the complex slot leakage magnetic field permeance function of the motor armature, and outputs the function to the slot leakage magnetic field synthesis module to provide key parameters for subsequent quasi-static distribution results of the leakage magnetic field at the motor conductor cross section.

[0178] The slot leakage magnetic field synthesis module receives the armature magnetic motive force obtained by the armature magnetic motive force calculation module and the slot leakage magnetic complex permeance function obtained by the slot leakage magnetic complex permeance function calculation module, as well as the slot leakage magnetic field data generated by the permanent magnet obtained by the finite element modeling and slot leakage magnetic field calculation module, performs synthesis calculation to obtain the quasi-static distribution of the leakage magnetic field at the motor conductor cross section, and transmits the result to the two-dimensional eddy current field calculation module as the initial condition for subsequent eddy current field analysis.

[0179] The two-dimensional eddy current field calculation module inputs the quasi-static distribution of the leakage magnetic field at the motor conductor cross section obtained by the slot leakage magnetic field synthesis module as boundary conditions, establishes a two-dimensional eddy current field mathematical model, and solves the distribution of the time-harmonic magnetic field at the conductor cross section to achieve fast and accurate calculation of the motor high-frequency magnetic field. The calculation results can be used for subsequent electromagnetic force calculation, conductor alternating current loss calculation, and other related analysis.

[0180] It should be noted that the motor high-frequency magnetic field, electromagnetic force and loss calculation system provided by the embodiment can be a computer program (including program code) running in a computer device, for example, the motor high-frequency magnetic field, electromagnetic force and loss calculation system is an application software; the motor high-frequency magnetic field, electromagnetic force and loss calculation system can be used to execute the corresponding steps in the above method provided by the embodiment of the application.

[0181] In some possible implementation manners, the motor high-frequency magnetic field, electromagnetic force and loss calculation system provided by the embodiment can be implemented in a combination of software and hardware, for example, the motor high-frequency magnetic field, electromagnetic force and loss calculation system provided by the embodiment of the application can be a processor in the form of a hardware decoding processor, which is programmed to execute the motor high-frequency magnetic field, electromagnetic force and loss calculation method provided by the embodiment of the application, for example, the processor in the form of a hardware decoding processor can adopt one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs) or other electronic elements.

[0182] In some possible implementation manners, the motor high-frequency magnetic field, electromagnetic force and loss calculation system provided by the embodiment can be implemented in a software manner, which can be software in the form of programs and plug-ins and the like, and include a series of modules to implement the motor high-frequency magnetic field, electromagnetic force and loss calculation method provided by the embodiment of the application.

[0183] The third aspect of the application also provides an electronic device, Figure 8 is a structural schematic diagram of the electronic device of the embodiment, as Figure 8As shown, the electronic device 1000 in the embodiment can include a processor 1001, a network interface 1004 and a memory 1005, in addition, the electronic device 1000 can further include a user interface 1003, and at least one communication bus 1002. Wherein, the communication bus 1002 is used to realize the connection communication between the components. Wherein, the user interface 1003 can include a display screen (Display), a keyboard (Keyboard), and the optional user interface 1003 can further include a standard wired interface, a wireless interface. The network interface 1004 can optionally include a standard wired interface, a wireless interface (such as a WI-FI interface). The memory 1004 can be a high-speed RAM memory, or a non-volatile memory, for example, at least one disk storage. The memory 1005 can optionally be at least one storage device located away from the aforementioned processor 1001. For example Figure 8 As shown, the memory 1005 as a computer readable storage medium can include an operating system, a network communication module, a user interface module and a device control application.

[0184] As shown, the electronic device 1000, the network interface 1004 can provide network communication function; and the user interface 1003 is mainly used for providing the interface for the user to input; and the processor 1001 can be used to call the device control application stored in the memory 1005, to realize: Figure 8 According to the operation condition of the motor, the phase current of the motor at any time is calculated; according to the slot-pole matching and winding distribution of the motor, the number of turns and the slot matrix of the motor are determined, and the armature magnetic motive force of the motor at any time is calculated in combination with the phase current;

[0185] The motor quasi-static finite element model is established, the slot leakage magnetic field generated under the fundamental current simulation is extracted by using the motor quasi-static finite element model; the motor quasi-static finite element simulation model excited by a single turn winding of a phase is established, the permanent magnet material properties are set to air, and the total slot leakage magnetic density distribution of the motor armature is calculated; the slot leakage magnetic field generated under the fundamental current simulation is subtracted from the total slot leakage magnetic density distribution of the motor armature, to obtain the slot leakage magnetic field generated by the permanent magnet;

[0186] In combination with the armature magnetic motive force of the motor at any time and the total slot leakage magnetic density distribution of the motor armature, the complex slot leakage magnetic field permeance function of the motor armature is calculated by using the magnetic field theory and numerical calculation method;

[0187]

[0188] ​According to the armature magnetic motive force of the motor at any time and the complex slot leakage magnetic field permeance function of the motor armature, the slot leakage magnetic field caused by the motor armature is calculated; the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet are synthesized to obtain the quasi-static distribution result of the leakage magnetic field at the motor conductor section;

[0189] A two-dimensional eddy current field mathematical model is established, and according to the differential equation of the time-harmonic field, the quasi-static distribution result of the leakage magnetic field at the motor conductor section is combined to solve the two-dimensional eddy current field mathematical model to obtain the distribution of the time-harmonic field at the conductor section.

[0190] According to the distribution of the time-harmonic field at the conductor section, the electromagnetic force and the conductor alternating current loss are calculated.

[0191] It should be understood that in some possible implementations, the processor 1001 described above can be a central processing unit (CPU), and the processor can also be other general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The memory can include read-only memory and random access memory, and provide instructions and data for the processor. A part of the memory can also include non-volatile random access memory. For example, the memory can also store device type information.

[0192] In specific implementations, the electronic device 1000 described above can execute the implementation manner provided by each step in the above Figure 1 by means of various functional modules built therein. For details, refer to the implementation manner provided by each step described above, which will not be repeated here.

[0193] The embodiment of the present application also provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method provided by each step in the above Figure 1 For details, refer to the implementation manner provided by each step described above, which will not be repeated here.

[0194] Any reference to storage, memory, database or other medium herein includes non-volatile and / or volatile storage. Non-volatile storage can include read-only memory (ROM), programmable ROM (PROM), electronically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile storage can include random-access memory (RAM), or external cache memory. By way of illustration, and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), Rambus direct memory access (RDMA), and Rambus in-memory direct computer bus RAM (RDRAM), etc.

[0195] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of calculating high-frequency magnetic field, electromagnetic force, and loss of an electric machine, characterized by, Comprising the following steps: S100: calculating the phase current of the motor at any time according to the motor operating condition; determining the number of turns and the slot matrix of the motor according to the slot-pole matching and winding distribution of the motor, and combining the phase current to calculate the armature magnetic motive force of the motor at any time; S200: establishing a motor quasi-static finite element model, extracting the slot leakage magnetic field generated under the simulation of the fundamental wave current by using the motor quasi-static finite element model; establishing a motor quasi-static finite element simulation model excited by a single turn winding of one phase, setting the permanent magnet material properties as air, and calculating the total slot leakage flux density distribution of the motor armature; subtracting the slot leakage magnetic field generated under the simulation of the fundamental wave current from the total slot leakage flux density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet; S300: combining the armature magnetic motive force of the motor at any time and the total slot leakage flux density distribution of the motor armature, and using the magnetic field theory and numerical calculation method to calculate the complex slot leakage magnetic field permeance function of the motor armature; S400: calculating the slot leakage magnetic field caused by the motor armature according to the armature magnetic motive force of the motor at any time and the complex slot leakage magnetic field permeance function of the motor armature; synthesizing the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the conductor cross section of the motor; S500: for the conductor region, a two-dimensional eddy current field mathematical model is established, the general solution form of the mathematical model is obtained after dimension reduction processing, and the boundary conditions are determined based on the quasi-static distribution result of the leakage magnetic field at the conductor cross section of the motor, so as to solve the distribution of the time-harmonic magnetic field at the conductor cross section; S600: calculating the electromagnetic force and the alternating current loss of the conductor according to the distribution of the time-harmonic magnetic field at the conductor cross section.

2. The method of claim 1, wherein, Step S100 includes: S101: setting motor operating state parameters to determine the operating condition of the motor; the motor operating state parameters include speed, torque, switching frequency and load type; S102: selecting a corresponding motor mathematical model to describe the operating characteristics of the motor according to the type of the motor; S103: calculating the phase current of the motor at any time by using the selected motor mathematical model and the determined motor operating state parameters; S104: determining the number of turns and the slot matrix of the motor according to the slot-pole matching and winding distribution of the motor; S105: combining the calculated phase current, the determined number of turns of the motor and the constructed slot matrix to calculate the armature magnetic motive force of the motor at any time.

3. The method of claim 2, wherein, The phase current of the motor at any time in step S103 is calculated by formula (1): I A,t = L' -1 (u A - e A ) (1) where I A,t is the phase current of the motor at any time; L' is the equivalent impedance matrix, containing resistance, inductance, step information, u A is the A-phase voltage, e A is the A-phase counter electromotive force.

4. The method of claim 3, wherein, The armature magnetic motive force f of the motor at any time in step S105 is calculated by formula (3): f = I A，t • M slot • N (3) where I A，t is the phase current of the motor at any time; M slot is the slot matrix of the motor; and N is the number of turns of the motor.

5. The method of claim 1-4, wherein, Step S200 includes: S201: establishing a motor quasi-static finite element model, Fourier transforming the motor phase current data when the motor is running to extract the current harmonic fundamental wave amplitude and phase; performing quasi-static finite element simulation with the fundamental wave current as input to simulate the magnetic field distribution of the motor under the action of the fundamental wave current; extracting the slot leakage magnetic field generated under the simulation of the fundamental wave current, recording the permeability distribution at this time, and freezing the permeability; S202: a quasi-static finite element simulation model of the motor excited by one phase and one turn winding is established; in the model, the permeability obtained in step S201 is kept unchanged, the material properties of the permanent magnet are set as air, a constant current with an amplitude of 1 is applied in the conductor, simulation calculation is performed, and the leakage flux density distribution in each slot of the stator is obtained; the leakage flux densities of slots of the same phase are superposed, and the total slot leakage flux density generated by the phase is obtained; S203: according to the relationship between the current amplitude of the three-phase winding of the motor and the symmetry of the magnetic circuit, the slot leakage flux density distributions of the remaining two phases are derived, and the slot leakage flux densities of the three phases are vector superposed to obtain the total slot leakage flux density distribution of the motor armature; S204: the slot leakage magnetic field generated under the simulation of the fundamental current is subtracted from the total slot leakage flux density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet.

6. The method of claim 1-4, wherein, The slot leakage field caused by the motor armature in step S400 Calculated by equation (5): wherein f is the armature magnetic motive force of the electric machine at any time instant; is the complex slot leakage field permeance function of the electric machine armature; The leakage magnetic field at the conductor cross section in step S400 is represented by formula (7): wherein, is the resultant flux density of slot leakage flux at the cross section of the motor conductor; is the slot leakage flux generated by the permanent magnet; is the slot leakage flux generated by the motor armature.

7. The method of claim 1-4, wherein, Step S500 includes: S501: a two-dimensional time differential equation of the eddy current field is established according to Maxwell's equations, and a micro-element method is used for dimension reduction processing to obtain a general solution form of the two-dimensional time differential equation; S502: the boundary conditions of the two-dimensional time differential equation are obtained according to the quasi-static magnetic field distribution of the conductor cross section; S503: the distribution of the time-harmonic magnetic field of the conductor cross section is obtained by substituting the boundary conditions into the general solution form of the two-dimensional time differential equation.

8. The method of claim 7, wherein, The two-dimensional time differential equation of the eddy current field in step S501 is: wherein B and E represent sinusoidally varying magnetic and electric fields, respectively, with units of amperes per meter and volts per meter, respectively; B represents the magnetic field ; and E represents the electric field ; and σ is the electrical conductivity of the wire, with units of siemens per meter; Ei represents the induced electric field due to the time-varying magnetic field; -j is the negative imaginary unit; ω is the angular velocity of the magnetic field rotation, with units of radians per second; and μ0is the vacuum permeability of the wire, with units of henries per meter. The general solution form of the two-dimensional time differential equation is shown by formula (12): where, represents the magnetic field component in the x-direction; represents the magnetic field component in the y-direction; A1, A2 are integration constants determined by boundary conditions; these constants are used to fit the solution of a particular problem to satisfy specific physical conditions or boundary conditions; e -γy is an exponential function representing the magnetic field strength decay in the y-direction; e γy is an exponential function representing the magnetic field strength growth in the y-direction; e -γx is an exponential function representing the magnetic field strength decay in the x-direction; e γx is an exponential function representing the magnetic field strength growth in the x-direction.

9. The method of claim 8, wherein: The boundary conditions of the two-dimensional time differential equation in step S502 include: The tangential magnetic flux density is continuous at the surface of the conductor, and the normal current density is continuous; At the boundary of the conductor, the magnetic field intensity should be zero; Inside the conductor, the magnetic field distribution under the time-harmonic electromagnetic field satisfies the distribution form in formula (14): wherein denotes the magnetic field strength a function of the positions x and y; denotes the magnetic field strength a function of the positions x and y; denotes the magnetic field strength a function of x, averaged over the x-direction; denotes the magnetic field strength a function of y, averaged over the y-direction; γ is the skin effect coefficient, i.e. the propagation constant; a, b are the geometric dimensions of the conductor in the x, y direction; ch is the hyperbolic cosine function; denotes the magnetic field strength averaged over the x-direction within a certain region S inside the conductor; denotes the magnetic field strength averaged over the y-direction within a certain region S inside the conductor; Step S503 includes: substituting the boundary conditions into the general solution form of the two-dimensional time differential equation formula (12) to solve the integral constants A1 and A2, and thus obtaining a special solution satisfying the boundary conditions, that is, the distribution of the time-harmonic magnetic field of the conductor cross section.

10. A system for calculating high frequency magnetic field, electromagnetic force and losses in an electrical machine, characterized by, The motor high-frequency magnetic field, electromagnetic force and loss calculation method comprises: The armature magnetic motive force calculation module is used to determine the operating condition of the motor, calculate the phase current of the motor at any time according to the operating condition of the motor, determine the number of turns and the slot matrix of the motor according to the slot pole matching and winding distribution of the motor, and calculate the armature magnetic motive force of the motor at any time in combination with the phase current; The finite element modeling and slot leakage magnetic field calculation module is used to establish a quasi-static finite element model of the motor, extract the slot leakage magnetic field generated under the simulation of the fundamental current by using the quasi-static finite element model of the motor, establish a quasi-static finite element simulation model of the motor excited by one phase and one turn winding, set the material properties of the permanent magnet as air, calculate the total slot leakage flux density distribution of the motor armature, and subtract the slot leakage magnetic field generated under the simulation of the fundamental current from the total slot leakage flux density distribution of the motor armature to obtain the slot leakage magnetic field generated by the permanent magnet; The slot leakage magnetic complex permeability function calculation module is configured to combine the armature magnetic motive force of the motor at any time and the total slot leakage magnetic flux density distribution of the motor armature, and to calculate the complex slot leakage magnetic field permeability function of the motor armature by using the magnetic field theory and the numerical calculation method. The slot leakage magnetic field synthesis module is configured to calculate the slot leakage magnetic field caused by the motor armature according to the armature magnetic motive force of the motor at any time and the complex slot leakage magnetic field permeability function of the motor armature, and to synthesize the slot leakage magnetic field caused by the motor armature and the slot leakage magnetic field generated by the permanent magnet to obtain the quasi-static distribution result of the leakage magnetic field at the motor conductor cross section. The two-dimensional eddy current field calculation module is configured to establish a two-dimensional eddy current field mathematical model, to obtain a general solution form of the mathematical model after dimension reduction processing, and to solve the general solution form by inputting the boundary condition determined based on the quasi-static distribution result of the leakage magnetic field at the motor conductor cross section to obtain the distribution of the time-harmonic magnetic field at the conductor cross section. The electromagnetic force and loss calculation module is configured to calculate the electromagnetic force and the conductor alternating current loss according to the distribution of the time-harmonic magnetic field at the conductor cross section.

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