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CN-121994913-A - 2.5D rapid calculation method for eddy current loss of rotor of high-speed permanent magnet motor

CN121994913ACN 121994913 ACN121994913 ACN 121994913ACN-121994913-A

Abstract

The invention discloses a 2.5D rapid calculation method for the eddy current loss of a rotor of a high-speed permanent magnet motor. Firstly, motor control parameters are obtained through a two-dimensional transient electromagnetic finite element model, and a magnetic field-circuit coupling model is constructed to obtain winding phase current containing harmonic waves. And secondly, respectively determining the axial lengths of the end effect of the magnetic field and the eddy current distribution, and constructing an end three-dimensional model by using larger values of the axial lengths. Then, the end three-dimensional model is coupled with the middle two-dimensional model determined based on the two-dimensional model through symmetrical boundary conditions to form a 2.5D equivalent model. Finally, the eddy current loss of the end part and the middle part is calculated by the model and summed to obtain the total eddy current loss. The invention greatly improves the calculation speed and reduces the consumption of calculation resources while ensuring the calculation precision.

Inventors

  • YANG JIANGTAO
  • PAN YUANHANG
  • LI QING
  • Yu Jianzong

Assignees

  • 湖南大学

Dates

Publication Date
20260508
Application Date
20260129

Claims (10)

  1. 1. A2.5D rapid calculation method for the eddy current loss of a rotor of a high-speed permanent magnet motor is characterized by comprising the following steps: s1, constructing a two-dimensional transient electromagnetic finite element calculation model of a high-speed permanent magnet motor, calculating control parameters of the motor based on the two-dimensional transient electromagnetic finite element model, and constructing a magnetic field-circuit direct coupling model to obtain winding phase currents containing current harmonics; s2, respectively determining the first axial length of the end effect of the high-speed permanent magnet motor caused by magnetic field distribution And end effect second axial length caused by vortex distribution ; S3, based on the first axial length And the second axial length Constructing an end three-dimensional model for representing three-dimensional electromagnetic characteristics of the end of the motor; S4, constructing a 2.5D equivalent model formed by coupling the end three-dimensional model and a middle two-dimensional model through symmetrical boundary conditions, wherein the middle two-dimensional model is determined based on a two-dimensional transient electromagnetic finite element model of the high-speed permanent magnet motor; S5, using the winding phase current containing the current harmonic as excitation, and respectively calculating the first eddy current loss of the rotor in an end region and the second eddy current loss of the rotor in a middle region by using the 2.5D equivalent model; And S6, summing the first eddy current loss and the second eddy current loss to obtain the total eddy current loss of the high-speed permanent magnet motor rotor.
  2. 2. The method for rapidly calculating the rotor eddy current loss of the high-speed permanent magnet motor 2.5D according to claim 1, wherein in the step S2, the first axial length is determined The method comprises the steps of constructing a three-dimensional static electromagnetic finite element model containing a stator core, an armature winding, a rotor sheath, a permanent magnet and a rotor core, acquiring distribution data of radial air gap magnetic flux density along the axial direction of a motor based on the three-dimensional static electromagnetic finite element model, and determining the first axial length according to the length of a transition zone from end part attenuation to axial middle stable value of magnetic field intensity in the distribution data 。
  3. 3. The method for rapidly calculating the rotor eddy current loss of the high-speed permanent magnet motor 2.5D according to claim 2, wherein in the step S2, the second axial length is determined The specific mode of (a) is as follows: according to the calculation formula of the skin depth of the conductor Calculated, wherein The maximum skin depth of the eddy currents induced for the rotor, For the resistivity of the conductive parts of the rotor, For the lowest frequency of the asynchronous magnetic field acting on the rotor, Is the magnetic permeability of the rotor conductive member.
  4. 4. The method for rapidly calculating the eddy current loss of the rotor of the high-speed permanent magnet motor according to claim 3, wherein in the step S3, the axial length of the end three-dimensional model is as follows By the formula A symmetrical boundary condition is determined and the three-dimensional model of the end portion is imposed on a section away from the end portion of the motor winding.
  5. 5. The method for rapidly calculating the eddy current loss of the rotor of the high-speed permanent magnet motor according to claim 4, wherein the axial effective length of the middle two-dimensional model in the step S4 is as follows Satisfy the formula Wherein For the axial effective length of the high-speed permanent magnet motor, For the axial length of the end three-dimensional model, the stacking height of the two-dimensional transient electromagnetic finite element calculation model and the axial length of the end three-dimensional model Equal.
  6. 6. The method for rapidly calculating the eddy current loss of the rotor of the high-speed permanent magnet motor according to claim 5, wherein the simulation step size is calculated by constructing a direct coupling model of a magnetic field and a circuit in the step S1 Carrier frequency according to control strategy Set up and meet 。
  7. 7. The method for rapidly calculating the eddy current loss of the rotor of the high-speed permanent magnet motor according to claim 6, wherein the step S4 further comprises the step of performing Fourier transform on the winding phase current containing current harmonics Performing a spectral analysis in which Is a winding phase current time domain waveform, In order to be of an angular frequency, In imaginary units, identifying the target harmonic frequency that is dominant in rotor eddy current loss According to the formula Calculating skin depth of corresponding rotor conductive component Construction of a fine skin effect mesh in a corresponding rotor conductive part, wherein mesh size Satisfy the following requirements 。
  8. 8. The method for 2.5D rapid calculation of rotor eddy current loss of high speed permanent magnet motor according to claim 7, wherein in step S5, the first eddy current loss is calculated by three-dimensional transient finite element method based on the end three-dimensional model, the second eddy current loss is calculated by two-dimensional transient finite element method based on the middle two-dimensional model, and the first eddy current loss is calculated by two-dimensional transient finite element method based on the middle two-dimensional model And the second eddy current loss Are all based on eddy current loss density integral formulas Calculated, wherein For the strength of the electric field, In order to achieve a current density of the material, To calculate the area volume.
  9. 9. The method for rapidly calculating 2.5D of eddy current loss of rotor of high-speed permanent magnet motor according to claim 8, wherein in step S6, the total eddy current loss is calculated by The calculation formula of (2) is Wherein For the first eddy current loss to be mentioned, For said second eddy current loss.
  10. 10. The method for rapidly calculating the rotor eddy current loss of the high-speed permanent magnet motor by using the 2.5D method according to claim 1, wherein the three-dimensional static electromagnetic finite element calculation model and the two-dimensional transient electromagnetic finite element calculation model adopt the same structural parameters, and the three-dimensional static electromagnetic finite element calculation model comprises stator core thickness, number of turns of an armature winding, rotor sheath thickness, permanent magnet size and rotor core diameter.

Description

2.5D rapid calculation method for eddy current loss of rotor of high-speed permanent magnet motor Technical Field The invention relates to the technical field of motors, in particular to a 2.5D rapid calculation method for the eddy current loss of a rotor of a high-speed permanent magnet motor. Background The high-speed permanent magnet motor is used as a special motor with high power density, high operation efficiency and good dynamic response characteristic, is increasingly widely applied to a plurality of key fields such as traditional industrial production, new energy power generation, novel green transportation, aerospace and the like in recent years, and becomes core equipment for promoting technical upgrading, energy conservation and consumption reduction of related industries. Along with the continuous improvement of the demands of industrial production for equipment compactness and high efficiency, the rotor speed is an important development trend of a high-speed permanent magnet motor, and the trend is to obviously improve the power density of the motor and bring a series of technical problems to be solved, wherein the problem of eddy current loss of the rotor is particularly outstanding. The rotor runs at a high speed to make the internal electromagnetic environment of the motor more complex, so that not only is the loss density of the rotor greatly increased, but also a large number of winding current harmonics are inevitably introduced in the execution process of a control strategy because the fundamental frequency of the motor is far higher than that of a common motor and the carrier ratio of a matched power electronic controller is relatively lower. These harmonic components interact with the motor rotor conductive components (including permanent magnets, rotor jackets, rotor cores, etc.), creating significant eddy current losses, which become key factors affecting the operational stability and service life of the motor. For a high-speed permanent magnet motor, the temperature rise problem caused by the eddy current loss of the rotor is especially fatal, the magnetic performance of the permanent magnet is irreversibly attenuated even in the event of loss of magnetism caused by the excessively high temperature, the structural integrity of a rotor sheath is damaged, the safety risk in a high-speed rotating state is caused, in addition, the aging speed of all parts in the motor is increased due to the temperature rise, and the reliability and the service life of the whole motor system are reduced. Therefore, the accurate calculation of the eddy current loss of the rotor is one of the core links of the design stage of the high-speed permanent magnet motor, and the calculation result directly provides key basis for temperature rise analysis of the motor, loss suppression measure formulation and cooling system optimization design. If the calculated value of the eddy current loss is too low, the heat dissipation design of the motor is insufficient, the rotor temperature exceeds a design threshold value in actual operation, serious potential safety hazards such as permanent magnet loss, rotor structure damage and the like are caused, if the calculated value is too conservative, the cooling system is huge in size and increased in cost, the further improvement of the power density of the motor is restricted, the design requirements of equipment compactness and light weight cannot be met, and the core development concept of the high-speed permanent magnet motor is violated. In the current technical system, the 3D transient finite element method is a mainstream method for calculating the eddy current loss of the rotor, and the method can more comprehensively simulate three-dimensional electromagnetic field distribution in the motor and consider complex physical phenomena such as rotor end effect, skin effect and the like, so that the method has higher calculation accuracy and universality and is widely applied to various high-precision electromagnetic calculation scenes. However, the method has the obvious defects that on one hand, a fine three-dimensional electromagnetic model needs to be built, the requirements on computer hardware resources (including processor performance, memory capacity, display card computing force and the like) are extremely high, and on the other hand, the three-dimensional transient simulation process involves a large number of iterative calculations, takes extremely long time, even a motor model with medium complexity, and can take hours or even days for complete calculation at a time. More importantly, when the influence of current harmonic waves on eddy current loss is required to be considered, the diversity and complexity of harmonic wave components can enable the calculated amount to increase exponentially, further increase the calculation load, greatly reduce the calculation efficiency, seriously slow down the design period of the high-speed permanent magnet motor, and c