US 2021/0240874 A1Published application

Method for optimizing structured mesh generation for a thermal analysis model of a rotor bar of an ac motor

AssigneeHunan University of Science and Technology

InventorsXiaoping ZHANG, Yuxuan GUO, Zhu ZHANG, Guanghui ZHU, Haipeng JIANG, Hongwei CHEN

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Abstract

Provided is a method for optimizing structured mesh generation for a thermal analysis model of a rotor bar of an AC motor. A quadrilateral is randomly added within the top surface of the thermal analysis model of the rotor bar. The polygonal top surface is divided into multiple quadrilateral areas by drawing lines from each vertex of the quadrilateral to each vertex of the top surface or two points selected randomly on each edge of the top surface, respectively. A fruit fly optimization algorithm is adopted to obtain a maximum value of the average quality of the quadrilateral areas in a division mode and corresponding coordinates of the vertices of the quadrilateral areas. The top surface is divided into multiple quadrilateral areas according to the division mode corresponding to the maximum average quality to divide the model of the rotor bar into multiple columnar models.

Claims9

Dependent claims

A method for optimizing structured mesh generation for a thermal analysis model of a rotor bar of an alternating current (AC) motor, comprising:

1) selecting a polygonal top surface of a model of the rotor bar as a meshing area;
establishing a rectangular coordinate system with any vertex of the top surface as an origin of the rectangular coordinate system to obtain rectangular coordinates of vertices of the top surface;
2) sequentially numbering the vertices of the top surface and two points randomly selected on each edge of the top surface with the origin of the rectangular coordinate system of the top surface as a start point;
3) adding a quadrilateral randomly within the top surface of the model;
dividing the top surface into a plurality of quadrilateral areas by drawing a line from each vertex of the quadrilateral to each vertex of the top surface or two points selected randomly on each edge of the top surface, respectively;
and obtaining all division modes that divide the top surface into a plurality of quadrilateral areas;
4) optimizing each of the division modes with coordinates of the vertices of each quadrilateral area except for the vertices of the top surface as an optimization object and an average quality of the quadrilateral areas as an optimization target using a fruit fly optimization algorithm, to obtain a maximum value of the average quality of each quadrilateral area in each division mode and corresponding coordinates of the vertices of the quadrilateral areas;
5) comparing maximum values of the average quality of the quadrilateral areas under the division modes to obtain a division mode corresponding to a maximum average quality of the quadrilateral areas and coordinates of vertices of the quadrilateral areas corresponding to the maximum average quality, wherein the division mode corresponding to the maximum average quality of the quadrilateral areas is taken as an optimal division mode;
and
6) dividing the model of the rotor bar into a plurality of columnar models having a quadrilateral top surface according to the optimal division mode obtained in step (5);
and subjecting the columnar models to structured meshing through a sweep method to obtain an optimal structured meshing result for the model of the rotor bar.

8 more elements

2) determining an initial size of meshes of the columnar models as follows:

V
=
S
i
3
2
,
(
11
)
wherein V is the initial size of meshes of the columnar models;
S is the area of the top surface;
and i is the number of quadrilateral areas on the top surface;
6-3) meshing the columnar models according to the initial size of meshes of the columnar models determined in step (6-2) using the sweep method;
6-4) performing thermal analysis on the finite element models after the meshing to obtain a thermal distribution of the columnar models, and selecting a temperature at any point on the model;
6-5) reducing a size of the meshes to half of the size of the meshes in previous meshing, and meshing the columnar models using the sweep method in step (6-3);
6-6) performing the thermal analysis on the finite element models after the meshing in step (6-5) to obtain the temperature at the same point as in step (6-4);
6-7) comparing the temperature obtained in step (6-6) with the temperature of the same point obtained in the previous thermal analysis to obtain a temperature deviation ΔTi:
ΔTi=|Ti−Ti−1)| (12),
wherein Ti is the temperature of the certain point on the model obtained from this thermal analysis;
T(i−1) is the temperature of the same point on the model obtained from the previous thermal analysis;
6-8) determining whether the temperature deviation ΔTi is within a preset threshold range:
ΔTi≤ΔTM (13),
wherein ΔTM is the preset threshold of the temperature deviation ΔTi;
if the temperature deviation is within the preset threshold range, proceeding to the next step;
otherwise, returning to step (6-5);
6-9) adopting the obtained meshes as the optimal structured meshing result of the columnar models.

24 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/235,866Filed 20 Apr 2021
Published: 5 Aug 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

G06F 30/20
Computer-aided design [CAD]: design optimisation, verification or simulation
G06F 30/23
Design optimisation, verification or simulation: using finite element methods [FEM] or finite difference methods [FDM]
G06F 30/10
Computer-aided design [CAD]: geometric CAD
H02K 17/20
Having rotors with internally short-circuited windings, e.g. cage rotors: having deep-bar rotors

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