Permanent magnet motor eddy current loss calculation method

Abstract

This application provides a method for calculating eddy current losses in permanent magnet motors, including: calculating multiple rotor eddy current loss transfer functions; performing three-dimensional finite element analysis with harmonic current excitation to obtain the first rotor eddy current loss and the permanent magnet eddy current loss; determining the rotor eddy current loss correction function; determining the permanent magnet eddy current loss distribution law function; performing three-dimensional finite element analysis with harmonic voltage excitation to obtain the second rotor eddy current loss; determining the rotor eddy current loss saturation influence function based on the second rotor eddy current loss and the permanent magnet eddy current loss; and determining the target rotor eddy current loss and the target permanent magnet eddy current loss based on multiple rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function. This application significantly improves the efficiency of power supply harmonic loss analysis while ensuring sufficient accuracy.

Description

Technical Field

[0001] This application relates to the field of permanent magnet motor technology, and in particular to a method for calculating eddy current losses in permanent magnet motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) possess outstanding advantages such as high power density, high efficiency, and wide speed range, making them a core component of high-performance drive systems. To achieve precise and flexible PMSM drive, pulse-width modulation (PWM) voltage source inverters have become standard configurations. However, during the switching process, the inverter inevitably generates non-sinusoidal stepped voltage waves, inducing a large number of time harmonic components and resulting in additional eddy current losses in the rotor core and permanent magnets, leading to decreased efficiency and increased rotor temperature. Considering that rotor eddy current losses are a crucial reference indicator for the optimized design of PMSMs, providing methods for calculating PMSM eddy current losses is an important research topic for designers.

[0003] In existing related technologies, the eddy current losses of permanent magnets in permanent magnet synchronous motors are calculated quickly and accurately using a three-dimensional Fourier series distribution. However, the above-mentioned technologies do not consider the influence of harmonic voltages and only calculate the relationship between the relevant electromagnetic parameters of the permanent magnets and the eddy current losses.

[0004] Existing technical solutions consider the impact of phase current harmonics on the eddy current losses of permanent magnets, achieving rapid and accurate calculation of eddy current losses across the entire operating domain. However, these solutions only account for the additional eddy current losses of permanent magnets under non-sinusoidal current excitation using a fitted expression, and may not achieve the expected high-precision loss calculation under complex voltage harmonic excitation conditions.

[0005] In existing technologies, the frozen incremental tensor reluctance method and the frequency domain finite element method are used to quickly calculate the PWM harmonic iron loss of a permanent magnet motor throughout its operating range. However, these technologies only calculate rotor iron loss from the perspective of current source excitation and require dozens of linear frequency domain finite element calculations at each operating point, which may not be able to quickly obtain rotor loss results for different motor topologies.

[0006] Therefore, how to provide a method for calculating eddy current losses of permanent magnet motors that can achieve rapid calculation while ensuring sufficient accuracy is a technical problem to be solved in this field. Summary of the Invention

[0007] This application provides a method for calculating eddy current losses in permanent magnet motors, aiming to provide a method that enables rapid calculation while ensuring sufficient accuracy, and is applicable to different motor topologies.

[0008] In a first aspect, embodiments of this application provide a method for calculating eddy current losses in a permanent magnet motor, the method comprising: Based on the multiple magnetic flux paths corresponding to the permanent magnet motor, the multiple rotor eddy current loss transfer functions corresponding to the multiple magnetic flux paths are calculated under harmonic voltage excitation. A finite element simulation model of the permanent magnet motor is established, and a three-dimensional finite element calculation is performed by adding harmonic current excitation to obtain the first rotor eddy current loss and the permanent magnet eddy current loss. Based on the first rotor eddy current loss and the permanent magnet eddy current loss, determine the rotor eddy current loss correction function; Based on the eddy current loss of permanent magnets in different regions, the distribution law function of eddy current loss of permanent magnets is determined. A finite element simulation model of the permanent magnet motor is established, and a three-dimensional finite element calculation is performed by adding harmonic voltage excitation to obtain the eddy current loss of the second rotor. Based on the eddy current loss of the second rotor and the eddy current loss of the permanent magnet, the saturation influence function of the rotor eddy current loss is determined; Based on the multiple rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function, the target rotor eddy current loss and the target permanent magnet eddy current loss are determined.

[0009] Optionally, the plurality of magnetic flux paths include a first magnetic flux path, a second magnetic flux path, and a third magnetic flux path; When the harmonic voltage is the h-th positive sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… When the harmonic voltage is the h-th negative sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… in, This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. R sThis indicates the phase resistance of the motor windings. N s This indicates the number of turns in series per phase of the motor winding, and N represents the mechanical speed of the motor rotor. p Indicates the number of pole pairs of the motor rotor. L s Indicates the phase inductance of the motor winding. k wv This represents the winding coefficient of the v-th winding.

[0010] Optionally, the harmonic current excitation includes: An ideal sinusoidal fundamental wave has an amplitude equal to the product of the rated current at rated speed and a first coefficient, where the first coefficient includes 1. The sum of the ideal sinusoidal fundamental wave and the first current harmonic, wherein the amplitude of the first current harmonic is the product of the rated current at rated speed and the second coefficient, wherein the second coefficient includes 0.25 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second current harmonic, wherein the amplitude of the second current harmonic is the product of the rated current at rated speed and the third coefficient, wherein the third coefficient includes 0.1 and has an order of 5; The sum of the ideal sinusoidal fundamental wave and the third current harmonic, wherein the amplitude of the third current harmonic is the product of the rated current at rated speed and the fourth coefficient, wherein the fourth coefficient includes 0.0625 and has an order of 8.

[0011] Optionally, the first rotor eddy current loss includes rotor core eddy current loss and permanent magnet eddy current loss. Wherein, the eddy current loss of the rotor core is the difference between the three-dimensional finite element calculation results of the rotor core under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor core under single fundamental wave excitation. The eddy current loss of the permanent magnet is the difference between the three-dimensional finite element calculation results of the rotor permanent magnet under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor permanent magnet under single fundamental wave excitation.

[0012] Optionally, the eddy current loss of the permanent magnet is the difference between the first three-dimensional finite element calculation result and the second three-dimensional finite element calculation result; Among them, the first three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under fundamental wave and different harmonic excitation. The second three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under single fundamental wave excitation.

[0013] Optionally, determining the rotor eddy current loss correction function based on the first rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss correction function is calculated using the following formula: k=1,2,3,… in, Let A represent the rotor eddy current loss correction function, B represent the correction function attenuation rate, and C represent the correction function offset. A, B, and C are obtained based on the fitting of the first rotor eddy current loss. Z represents the number of stator slots of the motor. For a positive-sequence h-th order voltage harmonic, h = 3k + 1 is satisfied; for a negative-sequence h-th order voltage harmonic, h = 3k - 1 is satisfied. p This indicates the number of rotor pole pairs of the motor.

[0014] Optionally, determining the eddy current loss distribution function of the permanent magnet based on the eddy current loss of different regions of the permanent magnet includes: The distribution law function of eddy current loss of permanent magnet is calculated by the following formula: in, The function representing the distribution law of eddy current losses in permanent magnets. P center This represents the average eddy current loss at the center of the permanent magnet. P edge1 This represents the average eddy current loss at the midpoint of the left edge of the permanent magnet. P edge2 This represents the average eddy current loss at the midpoint of the upper edge of the permanent magnet. P edge3 This represents the average eddy current loss at the midpoint of the right edge of the permanent magnet. P edge4 This represents the average eddy current loss at the midpoint of the lower edge of the permanent magnet. P bottom1 This represents the average eddy current loss at the lower left corner of the rotor permanent magnet. P bottom2 This represents the average eddy current loss at the upper left corner of the rotor permanent magnet. P bottom3 This represents the average eddy current loss at the upper right corner of the rotor permanent magnet. P bottom4 This represents the average eddy current loss at the lower right corner of the rotor permanent magnet. u and w Represents the normalized coordinates of the permanent magnet surface.

[0015] Optionally, the harmonic voltage excitation includes: The sum of the ideal sinusoidal fundamental wave and the first voltage harmonic, wherein the amplitude of the first voltage harmonic is the product of the fundamental wave voltage amplitude and the fifth coefficient, wherein the fifth coefficient includes 0.1 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second voltage harmonic, wherein the amplitude of the second voltage harmonic is the product of the fundamental wave voltage amplitude and the sixth coefficient, wherein the sixth coefficient includes 0.5 and has an order of 2; The second rotor eddy current loss is the difference between the three-dimensional finite element calculation results of the rotor under fundamental wave and different amplitude current harmonic excitation and the three-dimensional finite element calculation results of the rotor under single fundamental wave excitation.

[0016] Optionally, determining the rotor eddy current loss saturation influence function based on the second rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss saturation influence function is calculated using the following formula: in, The saturation effect function of rotor eddy current loss is represented by , and D and E represent undetermined parameters D and E obtained based on the fitting of the second rotor eddy current loss. U h This represents the amplitude of the h-th voltage harmonic. R s This indicates the phase resistance of the motor windings. L s N represents the phase inductance of the motor windings, and N represents the mechanical speed of the motor rotor.

[0017] Optionally, determining the target rotor eddy current loss and the target permanent magnet eddy current loss based on the plurality of rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function includes: The target rotor eddy current loss is determined using the following formula: The eddy current loss of the target permanent magnet is determined by the following formula: in, This represents the rotor eddy current loss corresponding to the first magnetic flux path. This represents the rotor eddy current loss corresponding to the second magnetic flux path. This represents the rotor eddy current loss corresponding to the third magnetic flux path. This represents the amplitude of the h-th voltage harmonic. This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. This represents the rotor eddy current loss correction function. This represents the saturation effect function of rotor eddy current losses. The function representing the distribution law of eddy current losses in permanent magnets. This represents the permanent magnet eddy current loss corresponding to the first permanent magnet region. This represents the permanent magnet eddy current loss corresponding to the second permanent magnet region.

[0018] This application provides a method for calculating eddy current losses in permanent magnet motors, including: calculating multiple rotor eddy current loss transfer functions corresponding to multiple magnetic flux paths under harmonic voltage excitation, based on multiple magnetic flux paths corresponding to the permanent magnet motor; establishing a finite element simulation model corresponding to the permanent magnet motor and adding harmonic current excitation for three-dimensional finite element calculation to obtain the first rotor eddy current loss and the permanent magnet eddy current loss; determining the rotor eddy current loss correction function based on the first rotor eddy current loss; determining the permanent magnet eddy current loss distribution law function based on the permanent magnet eddy current loss; establishing a finite element simulation model corresponding to the permanent magnet motor and adding harmonic voltage excitation for three-dimensional finite element calculation to obtain the second rotor eddy current loss; determining the rotor eddy current loss saturation influence function based on the second rotor eddy current loss; and determining the target rotor eddy current loss and the target permanent magnet eddy current loss based on multiple rotor eddy current loss transfer functions, rotor eddy current loss correction functions, permanent magnet eddy current loss distribution law function, and rotor eddy current loss saturation influence function. In this embodiment, by adding harmonic current excitation for three-dimensional finite element calculation, the first rotor eddy current loss and the permanent magnet eddy current loss are obtained, realizing the decoupling analysis of power supply voltage harmonics; by adding harmonic voltage excitation for three-dimensional finite element calculation, the second rotor eddy current loss is obtained, realizing the rapid and accurate calculation of rotor eddy current loss under voltage harmonic excitation of any component; thus, the efficiency of power supply harmonic loss analysis is greatly improved while ensuring sufficient accuracy. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the method for calculating eddy current losses of a permanent magnet motor provided in the embodiments of this application; Figure 2 This is a schematic diagram of the magnetic flux path provided in an embodiment of this application; Figure 3 This is an application flowchart of the permanent magnet motor eddy current loss calculation method provided in the embodiments of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] See Figure 1 , Figure 1 This is a flowchart of the method for calculating eddy current losses in a permanent magnet motor provided in an embodiment of this application, as shown below. Figure 1 As shown, the method includes the following steps: Step 101: Based on the multiple magnetic flux paths corresponding to the permanent magnet motor, calculate the multiple rotor eddy current loss transfer functions corresponding to the multiple magnetic flux paths under harmonic voltage excitation. Step 102: Establish the finite element simulation model corresponding to the permanent magnet motor, and add harmonic current excitation to perform three-dimensional finite element calculation to obtain the first rotor eddy current loss and permanent magnet eddy current loss. Step 103: Determine the rotor eddy current loss correction function based on the first rotor eddy current loss and the permanent magnet eddy current loss; Step 104: Determine the distribution law function of permanent magnet eddy current loss based on the permanent magnet eddy current loss corresponding to different regions of the permanent magnet. Step 105: Establish the finite element simulation model corresponding to the permanent magnet motor, and add harmonic voltage excitation to perform three-dimensional finite element calculation to obtain the second rotor eddy current loss. Step 106: Based on the eddy current loss of the second rotor and the eddy current loss of the permanent magnet, determine the rotor eddy current loss saturation influence function; Step 107: Based on the multiple rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function, determine the target rotor eddy current loss and the target permanent magnet eddy current loss.

[0023] The overall technical concept of this embodiment is to obtain the influence coefficient curve of different order components on eddy current loss under unit voltage excitation through the derived analytical formula. In this way, when the eddy current loss value under a certain frequency harmonic voltage excitation is obtained, the eddy current loss value can be pre-coefficientd to obtain the eddy current loss value of permanent magnet motor under different order harmonic voltage excitation.

[0024] First, the eddy current loss value under a certain low-frequency current harmonic excitation is obtained through simulation, and then the value is converted to the voltage end based on the harmonic impedance to obtain the pre-factor of the motor.

[0025] The amplitudes of different order voltage harmonics are calculated using the SVPWM power supply harmonic calculation model. These values ​​are then multiplied by the corresponding influence coefficients and summed. Finally, the values ​​are multiplied by the pre-coefficient to obtain the eddy current loss value under SVPWM modulation.

[0026] It should be understood that during finite element simulation, the permanent magnet and rotor core can be divided into multiple regions to obtain the pre-coefficients for different regions, thereby obtaining different eddy current loss results for multiple regions.

[0027] In this embodiment, by adding harmonic current excitation for three-dimensional finite element calculation, the first rotor eddy current loss and the permanent magnet eddy current loss are obtained, realizing the decoupling analysis of power supply voltage harmonics; by adding harmonic voltage excitation for three-dimensional finite element calculation, the second rotor eddy current loss is obtained, realizing the rapid and accurate calculation of rotor eddy current loss under voltage harmonic excitation of any component; thus, the efficiency of power supply harmonic loss analysis is greatly improved while ensuring sufficient accuracy.

[0028] Furthermore, this embodiment combines analytical methods and finite element methods, enabling rapid switching between different motor structure design schemes and obtaining rotor eddy current loss results under different schemes, which greatly improves the efficiency of the early motor optimization design process.

[0029] Optionally, the plurality of magnetic flux paths include a first magnetic flux path, a second magnetic flux path, and a third magnetic flux path; When the harmonic voltage is the h-th positive sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… When the harmonic voltage is the h-th negative sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… in, This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. R s This indicates the phase resistance of the motor windings. N s This indicates the number of turns in series per phase of the motor winding, and N represents the mechanical speed of the motor rotor. p Indicates the number of pole pairs of the motor rotor. L s Indicates the phase inductance of the motor winding. k wv This represents the winding coefficient of the v-th winding.

[0030] Please see Figure 2 , Figure 2 This is a schematic diagram of the magnetic flux path provided in the embodiments of this application. Figure 2 The first and second magnetic flux paths are shown.

[0031] In this embodiment, the rotor eddy current loss transfer function corresponding to the first magnetic flux path, the rotor eddy current loss transfer function corresponding to the second magnetic flux path, and the rotor eddy current loss transfer function corresponding to the third magnetic flux path can be determined by the above formula.

[0032] Optionally, the harmonic current excitation includes: An ideal sinusoidal fundamental wave has an amplitude equal to the product of the rated current at rated speed and a first coefficient, where the first coefficient includes 1. The sum of the ideal sinusoidal fundamental wave and the first current harmonic, wherein the amplitude of the first current harmonic is the product of the rated current at rated speed and the second coefficient, wherein the second coefficient includes 0.25 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second current harmonic, wherein the amplitude of the second current harmonic is the product of the rated current at rated speed and the third coefficient, wherein the third coefficient includes 0.1 and has an order of 5; The sum of the ideal sinusoidal fundamental wave and the third current harmonic, wherein the amplitude of the third current harmonic is the product of the rated current at rated speed and the fourth coefficient, wherein the fourth coefficient includes 0.0625 and has an order of 8.

[0033] In this embodiment, harmonic current excitation is added for three-dimensional finite element calculation, wherein the harmonic current excitation satisfies the above conditions.

[0034] Optionally, the first rotor eddy current loss includes rotor core eddy current loss and permanent magnet eddy current loss. Wherein, the eddy current loss of the rotor core is the difference between the three-dimensional finite element calculation results of the rotor core under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor core under single fundamental wave excitation. The eddy current loss of the permanent magnet is the difference between the three-dimensional finite element calculation results of the rotor permanent magnet under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor permanent magnet under single fundamental wave excitation.

[0035] Optionally, the eddy current loss of the permanent magnet is the difference between the first three-dimensional finite element calculation result and the second three-dimensional finite element calculation result; Among them, the first three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under fundamental wave and different harmonic excitation. The second three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under single fundamental wave excitation.

[0036] Optionally, determining the rotor eddy current loss correction function based on the first rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss correction function is calculated using the following formula: k=1,2,3,… in, Let A represent the rotor eddy current loss correction function, B represent the correction function attenuation rate, and C represent the correction function offset. A, B, and C are obtained based on the fitting of the first rotor eddy current loss. Z represents the number of stator slots of the motor. For a positive-sequence h-th order voltage harmonic, h = 3k + 1 is satisfied; for a negative-sequence h-th order voltage harmonic, h = 3k - 1 is satisfied. p This indicates the number of rotor pole pairs of the motor.

[0037] Optionally, determining the eddy current loss distribution function of the permanent magnet based on the eddy current loss of different regions of the permanent magnet includes: The distribution law function of eddy current loss of permanent magnet is calculated by the following formula: in, The function representing the distribution law of eddy current losses in permanent magnets. P center This represents the average eddy current loss at the center of the permanent magnet. P edge1 This represents the average eddy current loss at the midpoint of the left edge of the permanent magnet. P edge2 This represents the average eddy current loss at the midpoint of the upper edge of the permanent magnet. P edge3 This represents the average eddy current loss at the midpoint of the right edge of the permanent magnet.P edge4 This represents the average eddy current loss at the midpoint of the lower edge of the permanent magnet. P bottom1 This represents the average eddy current loss at the lower left corner of the rotor permanent magnet. P bottom2 This represents the average eddy current loss at the upper left corner of the rotor permanent magnet. P bottom3 This represents the average eddy current loss at the upper right corner of the rotor permanent magnet. P bottom4 This represents the average eddy current loss at the lower right corner of the rotor permanent magnet. u and w Represents the normalized coordinates of the permanent magnet surface.

[0038] This invention, through analytical analysis and finite element correction, further realizes the rapid calculation of eddy current loss distribution in the rotor permanent magnet region based on the eddy current loss of permanent magnets, which greatly improves the calculation efficiency of hot spot loss of permanent magnets.

[0039] Optionally, the harmonic voltage excitation includes: The sum of the ideal sinusoidal fundamental wave and the first voltage harmonic, wherein the amplitude of the first voltage harmonic is the product of the fundamental wave voltage amplitude and the fifth coefficient, wherein the fifth coefficient includes 0.1 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second voltage harmonic, wherein the amplitude of the second voltage harmonic is the product of the fundamental wave voltage amplitude and the sixth coefficient, wherein the sixth coefficient includes 0.5 and has an order of 2; The second rotor eddy current loss is the difference between the three-dimensional finite element calculation results of the rotor under fundamental wave and different amplitude current harmonic excitation and the three-dimensional finite element calculation results of the rotor under single fundamental wave excitation.

[0040] In this embodiment, harmonic voltage excitation is added for three-dimensional finite element calculation, wherein the harmonic voltage excitation satisfies the above conditions.

[0041] Optionally, determining the rotor eddy current loss saturation influence function based on the second rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss saturation influence function is calculated using the following formula: in, The saturation effect function of rotor eddy current loss is represented by , and D and E represent undetermined parameters D and E obtained based on the fitting of the second rotor eddy current loss. U h This represents the amplitude of the h-th voltage harmonic. R s This indicates the phase resistance of the motor windings. Ls N represents the phase inductance of the motor windings, and N represents the mechanical speed of the motor rotor.

[0042] Optionally, determining the target rotor eddy current loss and the target permanent magnet eddy current loss based on the plurality of rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function includes: The target rotor eddy current loss is determined using the following formula: The eddy current loss of the target permanent magnet is determined by the following formula: in, This represents the rotor eddy current loss corresponding to the first magnetic flux path. This represents the rotor eddy current loss corresponding to the second magnetic flux path. This represents the rotor eddy current loss corresponding to the third magnetic flux path. This represents the amplitude of the h-th voltage harmonic. This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. This represents the rotor eddy current loss correction function. This represents the saturation effect function of rotor eddy current losses. The function representing the distribution law of eddy current losses in permanent magnets. This represents the permanent magnet eddy current loss corresponding to the first permanent magnet region. This represents the permanent magnet eddy current loss corresponding to the second permanent magnet region.

[0043] In this embodiment, the rotor eddy current losses corresponding to the first magnetic flux path, the second magnetic flux path, the third magnetic flux path, the permanent magnet eddy current losses corresponding to the first permanent magnet region, and the second permanent magnet region are calculated using the above formulas. This enables rapid and accurate calculation of rotor eddy current losses under voltage harmonic excitation of any component.

[0044] For a better understanding of the overall technical solution, please refer to [link / reference]. Figure 3 , Figure 3 The application process shown includes the following steps: (1) Based on the flux path of the permanent magnet synchronous motor, calculate the rotor eddy current loss transfer function under harmonic voltage excitation.

[0045] (2) For the target permanent magnet synchronous motor, establish the corresponding finite element simulation model, and on the basis of the ideal sinusoidal current excitation, add a specific order of fixed amplitude harmonic current excitation to perform three-dimensional finite element calculation to obtain the rotor eddy current loss and the eddy current loss at the specific rotor permanent magnet position.

[0046] (3) Based on the mean value of rotor eddy current loss obtained in step (2), and based on the stator and rotor end structural parameters of permanent magnet synchronous motor, calculate the rotor eddy current loss correction function with undetermined parameter components under harmonic voltage excitation.

[0047] (4) Based on the mean value of eddy current loss at a specific rotor permanent magnet position obtained in step (2), and based on the skin effect of conductor eddy current, calculate the distribution law function of rotor permanent magnet eddy current loss with undetermined parameter components.

[0048] (5) For the target permanent magnet synchronous motor, establish the corresponding finite element simulation model, and on the basis of the ideal sinusoidal voltage excitation, add a harmonic voltage excitation with a fixed order and a specific amplitude to perform three-dimensional finite element calculation to obtain the rotor eddy current loss.

[0049] (6) Based on the mean value of rotor eddy current loss obtained in steps (2) and (5), calculate the rotor eddy current loss saturation influence function with undetermined parameter components based on the saturation effect.

[0050] (7) Based on the rotor eddy current loss transfer function in step (1), the rotor eddy current loss correction function in step (3), the rotor eddy current loss distribution law function in step (4), and the rotor eddy current loss saturation influence function in step (6), the rotor eddy current loss caused by any harmonic voltage component and the eddy current loss on any rotor permanent magnet region of any permanent magnet synchronous motor at any speed are calculated.

[0051] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0052] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0053] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for calculating eddy current losses in a permanent magnet motor, characterized in that, The method includes: Based on the multiple magnetic flux paths corresponding to the permanent magnet motor, the multiple rotor eddy current loss transfer functions corresponding to the multiple magnetic flux paths are calculated under harmonic voltage excitation. A finite element simulation model of the permanent magnet motor is established, and a three-dimensional finite element calculation is performed by adding harmonic current excitation to obtain the first rotor eddy current loss and the permanent magnet eddy current loss. Based on the first rotor eddy current loss and the permanent magnet eddy current loss, determine the rotor eddy current loss correction function; Based on the eddy current loss of permanent magnets in different regions, the distribution law function of eddy current loss of permanent magnets is determined. A finite element simulation model of the permanent magnet motor is established, and a three-dimensional finite element calculation is performed by adding harmonic voltage excitation to obtain the eddy current loss of the second rotor. Based on the eddy current loss of the second rotor and the eddy current loss of the permanent magnet, the saturation influence function of the rotor eddy current loss is determined; Based on the multiple rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function, the target rotor eddy current loss and the target permanent magnet eddy current loss are determined.

2. The method according to claim 1, characterized in that, The plurality of magnetic flux paths include a first magnetic flux path, a second magnetic flux path, and a third magnetic flux path; When the harmonic voltage is the h-th positive sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… When the harmonic voltage is the h-th negative sequence voltage harmonic, the transfer functions of the plurality of rotor eddy current losses satisfy the following formula: k=1,2,3,… in, This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. R s This indicates the phase resistance of the motor windings. N s This indicates the number of turns in series per phase of the motor winding, and N represents the mechanical speed of the motor rotor. p Indicates the number of pole pairs of the motor rotor. L s Indicates the phase inductance of the motor winding. k wv This represents the winding coefficient of the v-th winding.

3. The method according to claim 1, characterized in that, The harmonic current excitation includes: An ideal sinusoidal fundamental wave has an amplitude equal to the product of the rated current at rated speed and a first coefficient, where the first coefficient includes 1. The sum of the ideal sinusoidal fundamental wave and the first current harmonic, wherein the amplitude of the first current harmonic is the product of the rated current at rated speed and the second coefficient, wherein the second coefficient includes 0.25 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second current harmonic, wherein the amplitude of the second current harmonic is the product of the rated current at rated speed and the third coefficient, wherein the third coefficient includes 0.1 and has an order of 5; The sum of the ideal sinusoidal fundamental wave and the third current harmonic, wherein the amplitude of the third current harmonic is the product of the rated current at rated speed and the fourth coefficient, wherein the fourth coefficient includes 0.0625 and has an order of 8.

4. The method according to claim 1, characterized in that, The first rotor eddy current loss includes rotor core eddy current loss and permanent magnet eddy current loss. Wherein, the eddy current loss of the rotor core is the difference between the three-dimensional finite element calculation results of the rotor core under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor core under single fundamental wave excitation. The eddy current loss of the permanent magnet is the difference between the three-dimensional finite element calculation results of the rotor permanent magnet under fundamental wave and different harmonic excitation and the three-dimensional finite element calculation results of the rotor permanent magnet under single fundamental wave excitation.

5. The method according to claim 1, characterized in that, The eddy current loss of the permanent magnet is the difference between the first three-dimensional finite element calculation result and the second three-dimensional finite element calculation result; Among them, the first three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under fundamental wave and different harmonic excitation. The second three-dimensional finite element calculation result is the three-dimensional finite element calculation result corresponding to the midpoint, four corners and center of the four edges of the permanent magnet under single fundamental wave excitation.

6. The method according to claim 1, characterized in that, The step of determining the rotor eddy current loss correction function based on the first rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss correction function is calculated using the following formula: k=1,2,3,… in, Let A represent the rotor eddy current loss correction function, B represent the correction function attenuation rate, and C represent the correction function offset. A, B, and C are obtained based on the fitting of the first rotor eddy current loss. Z represents the number of stator slots of the motor. For a positive-sequence h-th order voltage harmonic, h = 3k + 1 is satisfied; for a negative-sequence h-th order voltage harmonic, h = 3k - 1 is satisfied. p This indicates the number of rotor pole pairs of the motor.

7. The method according to claim 1, characterized in that, The determination of the eddy current loss distribution law function of the permanent magnet based on the eddy current loss of different regions of the permanent magnet includes: The distribution law function of eddy current loss of permanent magnet is calculated by the following formula: in, The function representing the distribution law of eddy current losses in permanent magnets. P center This represents the average eddy current loss at the center of the permanent magnet. P edge1 This represents the average eddy current loss at the midpoint of the left edge of the permanent magnet. P edge2 This represents the average eddy current loss at the midpoint of the upper edge of the permanent magnet. P edge3 This represents the average eddy current loss at the midpoint of the right edge of the permanent magnet. P edge4 This represents the average eddy current loss at the midpoint of the lower edge of the permanent magnet. P bottom1 This represents the average eddy current loss at the lower left corner of the rotor permanent magnet. P bottom2 This represents the average eddy current loss at the upper left corner of the rotor permanent magnet. P bottom3 This represents the average eddy current loss at the upper right corner of the rotor permanent magnet. P bottom4 This represents the average eddy current loss at the lower right corner of the rotor permanent magnet. u and w Represents the normalized coordinates of the permanent magnet surface.

8. The method according to claim 1, characterized in that, The harmonic voltage excitation includes: The sum of the ideal sinusoidal fundamental wave and the first voltage harmonic, wherein the amplitude of the first voltage harmonic is the product of the fundamental wave voltage amplitude and the fifth coefficient, wherein the fifth coefficient includes 0.1 and has an order of 2; The sum of the ideal sinusoidal fundamental wave and the second voltage harmonic, wherein the amplitude of the second voltage harmonic is the product of the fundamental wave voltage amplitude and the sixth coefficient, wherein the sixth coefficient includes 0.5 and has an order of 2; The second rotor eddy current loss is the difference between the three-dimensional finite element calculation results of the rotor under fundamental wave and different amplitude current harmonic excitation and the three-dimensional finite element calculation results of the rotor under single fundamental wave excitation.

9. The method according to claim 1, characterized in that, The determination of the rotor eddy current loss saturation influence function based on the second rotor eddy current loss and the permanent magnet eddy current loss includes: The rotor eddy current loss saturation influence function is calculated using the following formula: in, The saturation effect function of rotor eddy current loss is represented by , and D and E represent undetermined parameters D and E obtained based on the fitting of the second rotor eddy current loss. U h This represents the amplitude of the h-th voltage harmonic. R s This indicates the phase resistance of the motor windings. L s N represents the phase inductance of the motor windings, and N represents the mechanical speed of the motor rotor.

10. The method according to claim 1, characterized in that, The determination of the target rotor eddy current loss and the target permanent magnet eddy current loss based on the plurality of rotor eddy current loss transfer functions, the rotor eddy current loss correction function, the permanent magnet eddy current loss distribution law function, and the rotor eddy current loss saturation influence function includes: The target rotor eddy current loss is determined using the following formula: The eddy current loss of the target permanent magnet is determined by the following formula: in, This represents the rotor eddy current loss corresponding to the first magnetic flux path. This represents the rotor eddy current loss corresponding to the second magnetic flux path. This represents the rotor eddy current loss corresponding to the third magnetic flux path. This represents the amplitude of the h-th voltage harmonic. This represents the rotor eddy current loss transfer function corresponding to the first magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the second magnetic flux path. This represents the rotor eddy current loss transfer function corresponding to the third magnetic flux path. This represents the rotor eddy current loss correction function. This represents the saturation effect function of rotor eddy current losses. The function representing the distribution law of eddy current losses in permanent magnets. This represents the permanent magnet eddy current loss corresponding to the first permanent magnet region. This represents the permanent magnet eddy current loss corresponding to the second permanent magnet region.

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