CN111104764B - Structured grid optimization division method for alternating current motor rotor conducting bar thermal analysis model - Google Patents
Structured grid optimization division method for alternating current motor rotor conducting bar thermal analysis model Download PDFInfo
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Abstract
The invention discloses an alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method. The method comprises the following steps: a quadrangle is added into the polygonal top surface of the rotor conducting bar thermal analysis model at will, leads are respectively led from each vertex of the quadrangle to each vertex of the top surface or two points arbitrarily selected on each side of the top surface, and the polygonal top surface is divided into a plurality of quadrangle areas; obtaining the maximum value of the average mass of each quadrilateral area and the corresponding vertex coordinates by adopting a fruit fly algorithm; obtaining a partition mode corresponding to the maximum value of the average quality; and dividing the top surface into a plurality of quadrilateral areas according to the obtained partition mode, dividing the rotor guide bar model into a plurality of columnar models with quadrilateral top surfaces, and performing structured grid division on the columnar models with the quadrilateral top surfaces by using a sweeping method to obtain an optimal structured grid division result. The invention can reduce the time of grid division, effectively improve the overall quality of grid division and improve the accuracy of thermal analysis of the alternating current motor.
Description
Technical Field
The invention relates to the field of alternating current motor thermal analysis, in particular to an alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method.
Background
The ac motor is widely used because of its advantages of simple structure, low cost, convenient maintenance, etc. However, as the power density of the alternating current motor is continuously improved, the unit volume loss generated during the operation of the alternating current motor is also continuously increased, so that the temperature rise of the motor is continuously improved. If the temperature rise of the motor is too high, faults such as motor rotor conducting bar fracture, winding insulation damage and the like can be caused, and therefore, the development of thermal analysis research on the alternating current motor to reduce the temperature rise of the alternating current motor has important significance.
At present, a simplified formula method, an equivalent thermal circuit method, a finite formula method, a finite element method and the like are mainly used for thermal analysis of the alternating current motor, wherein the finite element method has the advantages of good boundary adaptability, unified and universal algorithm, high accuracy and the like and is widely applied. When the finite element method is used for carrying out thermal analysis on the alternating current motor, the finite element model of the alternating current motor needs to be subjected to meshing division; the currently common mesh division method mainly comprises a triangular mesh division method and a quadrilateral mesh division method, wherein the quadrilateral mesh division method is more applied due to the characteristics of high calculation precision, high calculation speed and the like; meanwhile, the quadrilateral mesh division method is further divided into a structured mesh division method and an unstructured mesh division method, wherein the structured mesh division method has the characteristics of high mesh division speed, good quality and the like, so that the user generally prefers the quadrilateral mesh division method.
The rotor conducting bar of the alternating current motor is the position with the highest temperature rise of the whole motor in the running process, so that the improvement of the accuracy of the temperature field analysis result of the alternating current motor is particularly important. However, because the top surface of the rotor conducting bar is generally polygonal, when a quadrilateral structured grid division method is used for grid division, the polygonal top surface of the rotor conducting bar needs to be firstly divided into a plurality of quadrilateral areas, and at present, an empirical method is generally adopted when quadrilateral areas are divided aiming at the polygonal top surface, so that the requirement on a user is high, and the grid division efficiency is low and the quality is poor.
Disclosure of Invention
In order to solve the technical problem, the invention provides an alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method.
The technical scheme for solving the problems is as follows: a structured grid optimization division method of an alternating current motor rotor conducting bar thermal analysis model comprises the following steps:
(1) selecting the polygonal top surface of the rotor guide bar model as a grid division area, and establishing a rectangular coordinate system with any vertex of the top surface as a coordinate origin on the top surface of the polygonal top surface to obtain a rectangular coordinate of each vertex of the top surface;
(2) respectively numbering the top points and the two points randomly selected on the sides of the top surface in sequence by taking the top surface coordinate origin as a starting point;
(3) a quadrangle is arbitrarily added in the top surface of the model, leads are respectively led to each vertex of the top surface or two points arbitrarily selected on each edge of the top surface through each vertex of the quadrangle, so that the top surface is divided into a plurality of quadrangle areas, and all partition modes of dividing the top surface into a plurality of quadrangle areas are obtained;
(4) aiming at each partition mode, the vertex coordinates of each quadrilateral area are taken as an optimization object, the average mass of each quadrilateral area except the top vertices is taken as an optimization target, and the optimization is carried out by adopting a drosophila algorithm so as to obtain the maximum value of the average mass of each quadrilateral area and the vertex coordinates corresponding to each quadrilateral area in the partition mode;
(5) comparing the average quality maximum values under various partition modes to obtain the partition mode corresponding to the maximum value and the vertex coordinates of each quadrilateral area;
(6) and (5) dividing the rotor guide bar model into a plurality of columnar models with quadrangular top surfaces according to the optimal partition mode obtained in the step (5), and performing structured grid division on each columnar model by using a sweeping method to obtain an optimal structured grid division result of the rotor guide bar model.
In the above method for optimally dividing the structured grid of the thermal analysis model of the rotor conducting bar of the alternating current motor, in the step (2), the numbers of the two points arbitrarily selected from each vertex of the top surface and each edge of the top surface are as follows:
(2-1) for convenience, each vertex of the top surface is called an angular point, and two points arbitrarily selected on each edge of the top surface are called edge points;
(2-2) numbering each angular point and each side point respectively;
(2-3) numbering other angular points in sequence in a clockwise direction or an anticlockwise direction by taking the angular point where the origin of coordinates is located as a No. 1 angular point;
(2-4) numbering each side point according to the same winding direction of the angular point numbers, taking the first side point encountered by the angular point No. 1 in the corresponding winding direction as the side point No. 1, and numbering the rest side points in sequence.
In the above method for optimizing and dividing the structured grid of the thermal analysis model of the rotor conducting bar of the alternating current motor, in the step (3), a quadrangle is arbitrarily added to the top surface of the model, and the numbering rules of each vertex of the quadrangle are as follows:
(3-1-1) for convenience, each vertex of the quadrangle is referred to as an interior point;
(3-1-2) any one inner point is an inner point No. 1, and all the inner points are numbered according to the same winding direction of the angular point numbers.
In the above method for optimally dividing the structured grid of the thermal analysis model of the rotor conducting bar of the alternating current motor, in the step (3), the top surface is divided into a plurality of quadrilateral areas, and the specific rule is as follows:
(3-2-1) for convenience, the connecting lines of the inner points and the angular points, the inner points and the odd-numbered side points, and the inner points and the even-numbered side points are respectively referred to as the first, second, and third types of wires, wherein the inner points are referred to as the left end points of the three types of wires, and the other end points are referred to as the right end points of the wires.
(3-2-2) setting the number of corner points of the top surface of the polygon as n and the number of side points as m, and comprising: m is 2 n.
(3-2-3) determining a first lead of the partition, i.e., an initial lead; the initial lead is a connecting line of the No. 1 inner point and the No. 1 angular point or a connecting line of the No. 1 inner point and the No. 1 side point.
(3-2-4) determining a second lead according to the initial lead type, the quadrilateral partition mode and the endpoint number increasing rule:
if the initial lead is a connecting line between the inner point No. 1 and the angular point No. 1, the second lead includes the following four conditions: the No. 1 inner point is connected with the No. 3 edge point, the No. 1 inner point is connected with the No. 3 corner point, the No. 2 inner point is connected with the No. 1 edge point, and the No. 2 inner point is connected with the No. 2 corner point;
if the initial lead is a connection line between the No. 1 inner point and the No. 1 side point, the second lead comprises the following four conditions: no. 1 interior point links to each other with No. 3 limit point, No. 1 interior point links to each other with No. 3 corner point, No. 2 interior point links to each other with No. 2 limit point, No. 2 interior point links to each other with No. 2 corner point.
(3-2-5) determining a third lead according to the determined second lead type, the quadrilateral partition mode and the endpoint number increasing rule, wherein the method comprises the following 5 conditions:
if the second lead is the first type of lead and the second lead and the initial lead are connected to the same inner point, that is, the second lead is a connection line between the number 1 inner point and the number 3 angular point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 5 edge point, and the No. 2 inner point is connected with the No. 4 corner point;
if the second lead is the first type of lead and the second lead is connected to the initial lead at a different inner point, i.e. the second lead is a connection line between the number 2 inner point and the number 2 angular point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 5 edge point, the No. 2 inner point is connected with the No. 4 corner point, the No. 3 inner point is connected with the No. 3 edge point, and the No. 3 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at the same inner point, namely the second lead is the connection line of the No. 1 inner point and the No. 3 side point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 4 edge point, and the No. 2 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at different inner points, namely the second lead is a connection line of the No. 2 inner point and the No. 1 side point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 3 edge point, the No. 2 inner point is connected with the No. 3 corner point, the No. 3 inner point is connected with the No. 2 edge point, and the No. 3 inner point is connected with the No. 2 corner point;
if the second lead is the third type lead and the second lead is connected with the initial lead at different inner points, that is, the second lead is a connection line between the No. 2 inner point and the No. 2 side point, the third lead has the following three conditions: no. 2 interior point links to each other with No. 3 limit point, No. 2 interior point links to each other with No. 3 corner point, No. 3 interior point links to each other with No. 2 corner point.
(3-2-6) determining the next lead according to the same rule, namely the last lead type determined in the previous step and the quadrilateral partition mode and endpoint number increasing rule, including the following 5 cases:
if the last determined lead is the first type of lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (2j-1) side point, and the (i +1) inner point is connected with the (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the first type of lead and the last determined lead is connected to the previous lead at a different interior point, the next lead has the following four conditions: the number i inner point is connected with the number (2j +1) edge point, the number i inner point is connected with the number (j +2) corner point, the number (i +1) inner point is connected with the number (2j-1) edge point, and the number (i +1) inner point is connected with the number (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the second type lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (j +1) side point, and the (i +1) inner point is connected with the (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the determined last lead is the second type lead and the determined last lead is connected to the previous lead at a different inner point, the next lead has the following four conditions: the number i inner point is connected with the number (j +2) edge point, the number i inner point is connected with the number (j +5)/2 corner point, the number (i +1) inner point is connected with the number (j +1) edge point, and the number (i +1) inner point is connected with the number (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last lead is determined to be the third type of lead, the next lead has the following three conditions: the number i inner point is connected with the number (j +1) side point, the number i inner point is connected with the number (j + 4)/number 2 corner point, and the number (i +1) inner point is connected with the number (j + 2)/number 2 corner point; and i and j are the left end point number and the right end point number of the determined last lead respectively.
(3-2-7) judging whether the endpoint number of the next lead determined in the step (3-2-6) has an overrun condition, if the endpoint number has one of the following conditions, judging that the endpoint number is overrun:
(a) the number of the left endpoint is greater than 4;
(b) if the right end point is an angular point, the number of the end point is greater than n;
(c) if the right end point is an odd-numbered side point, and the end point number is greater than (m-1);
(d) if the right endpoint is an even number of side points, and the endpoint number is more than m;
if any of the above conditions occurs in the determined end point number of the next lead, the lead is deleted.
(3-2-8) determining the next lead according to the steps (3-2-6) - (3-2-7) until the left and right end point numbers of the determined last lead reach the set values, namely the left end point number is equal to 4, and the right end point number meets one of the following conditions:
if the last lead is the first type of lead, the number of the right end point is equal to n, namely: j is n, wherein j is the right end point number;
if the last lead is the second type lead, the right end point number satisfies: j +1 ═ m, where j is its right end point number;
if the last lead is a third lead, the right end point number is equal to m, namely: j is m, wherein j is the right end point number.
(3-2-9) dividing the top surface into a plurality of quadrangular areas and determining the corresponding partition modes according to the determined lead types.
In the above method for optimizing and dividing the structured grid of the alternating current motor rotor conducting bar thermal analysis model, the fruit fly algorithm is adopted in the step (4) to optimize the average quality of the quadrilateral area, and the specific steps are as follows:
initializing the fruit fly population scale, population iteration times and fruit fly flying radius parameters;
step (4-2), obtaining linear equations of all sides of the top surface according to coordinates of all corner points of the polygonal top surface;
giving the coordinates of the edge point and the inner point of the individual fruit fly of the first generation to respectively distribute the coordinates at random positions of the side line of the top surface and the inside of the top surface;
step (4-4), calculating the average mass value of the quadrilateral area corresponding to the individual drosophila melanogaster of the first generation;
step (4-5), comparing the average mass values of quadrilateral areas corresponding to the individual drosophila melanogaster of the first generation, and reserving the maximum value and the coordinates of the corresponding inner point and edge point;
step (4-6), endowing the next generation of fruit fly individual inner point and edge point coordinates, and respectively distributing the coordinates at random positions in a circle with the reserved inner point and edge point as the center of the circle and the flying radius of the fruit fly as the radius;
step (4-7), calculating the average mass of the quadrilateral area corresponding to each drosophila individual in the step (4-6);
step (4-8), comparing the average quality of the quadrilateral areas corresponding to the fruit fly individuals to obtain the maximum value and the coordinates of the corresponding inner points and side points;
step (4-9), comparing the maximum value of the average quality of the quadrilateral area obtained in the step (4-8) with the maximum value of the average quality of the quadrilateral area reserved last time, and reserving the larger average quality value of the quadrilateral area and the corresponding coordinates of the inner point and the edge point;
step (4-10), repeatedly executing steps (4-6) - (4-9) until the number of operation times reaches the number of population iteration times;
and (4-11) obtaining the final average mass maximum value of the quadrilateral area and the coordinates of the corresponding inner point and edge point.
The alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method includes the following specific steps:
in the formula: q _ average represents the average quality of each quadrilateral area in a partition mode, l represents the number of quadrilateral areas in the partition mode, and q represents the average quality of each quadrilateral area in the partition modeiRepresenting the quality value of the ith quadrilateral area.
The alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method comprises the following specific steps:
(1) the numbers of all vertexes of the ith quadrangle are 1, 2, 3 and 4 in sequence, the vertical coordinates of all vertexes are 0, and the mixed products a, b and c are calculated according to the following relational expressions:
in the formula: each vector is a three-dimensional vector.
(2) And judging the quadrilateral type according to the values of the obtained mixed products a, b and c:
if a is greater than 0, b is greater than 0, and c is less than 0, the quadrangle is a convex quadrangle;
if a >0, b <0, c <0 or a >0, b >0, c >0 or a <0, b >0, c <0 or a <0, b <0, then the quadrilateral is a concave quadrilateral;
if a is greater than 0, b is less than 0, c is greater than 0 or a is less than 0, b is greater than 0, c is greater than 0, then the four vertex connecting lines are crossed;
(3) from the quadrilateral type obtained above, its quality value is determined using the following relation:
in the formula: x and y are self-set penalty coefficients<x<0，JRThe ratio of the Jacobian determinant value minimum value and the Jacobian determinant value maximum value corresponding to each integral point of the quadrangle is as follows:
in the formula: | J-minIs the minimum value of Jacobian determinant corresponding to each integral point of the quadrangle, | JmaxThe maximum value of the Jacobian determinant corresponding to each integral point of the quadrangle is obtained by calculating the Jacobian determinant corresponding to each integral point of the quadrangle from the coordinates of each vertex of the quadrangle, and the calculation formula is as follows:
|J|1＝(x2-x1)(y4-y1)-(x4-x1)(y2-y1) (7)
|J|2＝(x3-x2)(y1-y2)-(x1-x2)(y3-y2) (8)
|J|3＝(x4-x2)(y2-y3)-(x2-x3)(y4-y3) (9)
|J|4＝(x1-x4)(y3-y4)-(x3-x4)(y1-y4) (10)
in the formula: x is the number of1-x4Is the abscissa, y, of each vertex of the quadrilateral1-y4The ordinate of each vertex of the quadrilateral.
In the above method for optimally dividing the structured grid of the thermal analysis model of the rotor conducting bar of the alternating current motor, in step 6, the structural grid division is performed on each columnar model by using the sweep method, and the specific method is as follows:
step (6-1), dividing the top surface into a plurality of quadrilateral areas according to the partition mode obtained in the step (5), and dividing the rotor conducting bar model into cylindrical models with a corresponding number of quadrilateral top surfaces according to the obtained quadrilateral areas;
step (6-2), determining the initial grid size of each columnar model, specifically as follows:
in the formula: v is the initial grid size of each columnar model, S is the area of the top surface, and i is the number of quadrilateral areas divided by the top surface;
step (6-3), performing meshing on each columnar model by using a sweeping method according to the initial mesh size determined in the step (6-2);
step (6-4), carrying out thermal analysis on the finite element model subjected to grid division to obtain the thermal distribution of each columnar model, and taking the temperature of any point on the model as a value to be compared;
step (6-5), reducing the grid to half of the size of the grid at the previous time, and then carrying out grid division on each columnar model by using the same sweeping method as the step (6-3);
step (6-6), carrying out thermal analysis on the finite element model subjected to meshing in the step (6-5) to obtain a temperature value at the same point as that in the step (6-4);
step (6-7), comparing the temperature value obtained in step (6-6) with the temperature value of the same point obtained in the last thermal analysis to obtain a difference value △ Ti：
△Ti＝|Ti-T(i-1)| (12)
In the formula: t isiThe temperature value T of a certain point on the model obtained by the thermal analysis(i-1)The temperature value of the same point on the model obtained by the last thermal analysis is obtained;
step (6-8), judging the temperature deviation △ TiWhether the current is within a preset threshold range, namely:
△Ti≤△TM(13)
in the formula, △ TMIs a temperature deviation of △ TiIs set to the preset threshold value.
If the temperature deviation is △ TiIf the preset threshold value is within the range, entering the next step, otherwise, returning to the step (6-5);
and (6-9) taking the obtained meshing result as the optimal structured meshing result of each columnar model.
Compared with the prior art, the method comprises the steps of firstly, arbitrarily adding a quadrangle in the polygonal top surface of a rotor conducting bar thermal analysis model, and leading wires from each vertex of the quadrangle to each vertex of the top surface or two points arbitrarily selected on each side of the top surface respectively, so that the polygonal top surface is divided into a plurality of quadrangle areas and corresponding partition modes are obtained; then aiming at each partition mode, optimizing by adopting a drosophila algorithm to obtain the maximum value of the average mass of each quadrilateral area and the vertex coordinates corresponding to each quadrilateral area in the partition mode; comparing the average quality maximum values under each partition mode to obtain the partition mode corresponding to the maximum value; dividing the top surface into a plurality of quadrilateral areas according to the partition mode corresponding to the maximum value, and dividing the rotor guide bar model into a plurality of columnar models with quadrilateral top surfaces; and finally, performing structured grid division on the columnar models with quadrilateral top surfaces by using a sweeping method to obtain the optimal structured grid division result of the rotor guide bar model. The invention has the advantages that: the complex model with the polygonal top surface is divided into a plurality of simple models with quadrilateral top surfaces, so that the mesh division time can be reduced; the highest average quality of each quadrilateral region is obtained through an optimization algorithm, and the overall quality of grid division can be effectively improved, so that the aim of improving the thermal analysis precision of the alternating current motor is fulfilled.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a flow chart of a method for partitioning a polygonal top surface of a thermal analysis model of an AC motor rotor bar according to the present invention;
FIG. 3 is a flow chart of optimizing the average mass of a quadrilateral area by using a drosophila algorithm in the present invention;
FIG. 4 is a flow chart of the present invention for structured meshing of various columnar models using a sweep method;
FIG. 5 is a top view of a Y100L2-4 type AC motor rotor bar according to an embodiment of the present invention;
fig. 6 is a schematic diagram of numbering corner points and edge points on the top surface of a rotor bar of a Y100L2-4 type ac motor according to an embodiment of the present invention;
FIG. 7 is an optimization process curve for optimizing the average quality of a quadrilateral area by using a drosophila algorithm in the present invention;
FIG. 8 is a schematic diagram of the top surface of a rotor bar model according to the present invention;
FIG. 9 is a schematic diagram of the rotor bar model structured grid optimization division according to the present invention;
table 1 shows the comparison of the results before and after the optimization of the rotor bar model structured grid division.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Referring to fig. 1, fig. 1 is a flowchart of an optimization division method for a structured grid of an alternating current motor rotor conducting bar thermal analysis model in the invention, and the method comprises the following steps:
selecting a polygonal top surface of a rotor guide bar model as a grid division area, and establishing a rectangular coordinate system with any vertex of the top surface as a coordinate origin on the top surface of the polygonal top surface to obtain a rectangular coordinate of each vertex of the top surface;
and (2) respectively numbering the vertexes of the top surface and the two randomly selected points on the edges of the top surface in sequence by taking the origin of the coordinates of the top surface as a starting point, wherein the specific numbering rule is as follows:
(2-1) for convenience, each vertex of the top surface is called an angular point, and two points arbitrarily selected on each edge of the top surface are called edge points;
(2-2) numbering each angular point and each side point respectively;
(2-3) numbering other angular points in sequence in a clockwise direction or an anticlockwise direction by taking the angular point where the origin of coordinates is located as a No. 1 angular point;
(2-4) numbering each side point according to the same winding direction of the angular point numbers, taking the first side point encountered by the angular point No. 1 in the corresponding winding direction as the side point No. 1, and numbering the rest side points in sequence.
And (3) adding a quadrangle into the top surface of the model at will, and leading lines to the vertexes of the top surface or two points randomly selected on the edges of the top surface through the vertexes of the quadrangle respectively so as to divide the top surface into a plurality of quadrangle areas and obtain all partition modes for dividing the top surface into a plurality of quadrangle areas.
Before the top surface is divided into a plurality of quadrilateral areas, firstly, numbering the quadrilateral vertexes added in the top surface, wherein the numbering rules are as follows: for convenience, each vertex of the quadrangle is called an inner point, one inner point is taken as a No. 1 inner point, and the rest inner points are numbered according to the same winding direction of the angular point numbers.
With reference to fig. 2, the top surface is divided into a plurality of quadrilateral areas according to the following specific rules:
step (3-2-1), for convenience, connecting lines of the inner points and the angular points, the inner points and the odd-numbered side points, and the inner points and the even-numbered side points are respectively called a first type lead, a second type lead and a third type lead, wherein the inner points are called left end points of the three types of leads, and the other end points are called right end points of the leads;
step (3-2-2), the number of corners of the polygon top surface is set to be n, the number of edges is set to be m, and the method comprises the following steps: m is 2 n;
step (3-2-3), determining a first lead of the partition, namely an initial lead; the initial lead is a connecting line of a No. 1 inner point and a No. 1 angular point or a connecting line of a No. 1 inner point and a No. 1 side point;
(3-2-4) determining a second lead according to the initial lead type, the quadrilateral partition mode and the endpoint number increasing rule:
if the initial lead is a connecting line between the inner point No. 1 and the angular point No. 1, the second lead includes the following four conditions: the No. 1 inner point is connected with the No. 3 edge point, the No. 1 inner point is connected with the No. 3 corner point, the No. 2 inner point is connected with the No. 1 edge point, and the No. 2 inner point is connected with the No. 2 corner point;
if the initial lead is a connection line between the No. 1 inner point and the No. 1 side point, the second lead comprises the following four conditions: no. 1 interior point links to each other with No. 3 limit point, No. 1 interior point links to each other with No. 3 corner point, No. 2 interior point links to each other with No. 2 limit point, No. 2 interior point links to each other with No. 2 corner point.
Step (3-2-5), determining a third lead according to the determined second lead type, the quadrilateral partition mode and the endpoint number increasing rule, wherein the method comprises the following 5 conditions:
if the second lead is the first type of lead and the second lead and the initial lead are connected to the same inner point, that is, the second lead is a connection line between the number 1 inner point and the number 3 angular point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 5 edge point, and the No. 2 inner point is connected with the No. 4 corner point;
if the second lead is the first type of lead and the second lead is connected to the initial lead at a different inner point, i.e. the second lead is a connection line between the number 2 inner point and the number 2 angular point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 5 edge point, the No. 2 inner point is connected with the No. 4 corner point, the No. 3 inner point is connected with the No. 3 edge point, and the No. 3 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at the same inner point, namely the second lead is the connection line of the No. 1 inner point and the No. 3 side point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 4 edge point, and the No. 2 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at different inner points, namely the second lead is a connection line of the No. 2 inner point and the No. 1 side point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 3 edge point, the No. 2 inner point is connected with the No. 3 corner point, the No. 3 inner point is connected with the No. 2 edge point, and the No. 3 inner point is connected with the No. 2 corner point;
if the second lead is the third type lead and the second lead is connected with the initial lead at different inner points, that is, the second lead is a connection line between the No. 2 inner point and the No. 2 side point, the third lead has the following three conditions: the No. 2 inner point is connected with the No. 3 edge point, the No. 2 inner point is connected with the No. 3 corner point, and the No. 3 inner point is connected with the No. 2 corner point;
step (3-2-6), determining the next lead according to the same rule, namely according to the determined last lead type, the quadrilateral partition mode and the endpoint number increasing rule, wherein the method comprises the following 5 conditions:
if the last determined lead is the first type of lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (2j-1) side point, and the (i +1) inner point is connected with the (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the first type of lead and the last determined lead is connected to the previous lead at a different interior point, the next lead has the following four conditions: the number i inner point is connected with the number (2j +1) edge point, the number i inner point is connected with the number (j +2) corner point, the number (i +1) inner point is connected with the number (2j-1) edge point, and the number (i +1) inner point is connected with the number (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the second type lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (j +1) side point, and the (i +1) inner point is connected with the (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the determined last lead is the second type lead and the determined last lead is connected to the previous lead at a different inner point, the next lead has the following four conditions: the number i inner point is connected with the number (j +2) edge point, the number i inner point is connected with the number (j +5)/2 corner point, the number (i +1) inner point is connected with the number (j +1) edge point, and the number (i +1) inner point is connected with the number (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last lead is determined to be the third type of lead, the next lead has the following three conditions: the number i inner point is connected with the number (j +1) side point, the number i inner point is connected with the number (j + 4)/number 2 corner point, and the number (i +1) inner point is connected with the number (j + 2)/number 2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
and (3-2-7) judging whether the endpoint number of the next lead determined in the step (3-2-6) has an overrun condition, and if the endpoint number has one of the following conditions, judging that the endpoint number is overrun:
(a) the number of the left endpoint is greater than 4;
(b) if the right end point is an angular point, the number of the end point is greater than n;
(c) if the right end point is an odd-numbered side point, and the end point number is greater than (m-1);
(d) if the right endpoint is an even number of side points, and the endpoint number is more than m;
if any of the above conditions occurs in the determined end point number of the next lead, the lead is deleted.
And (3-2-8) determining the next lead according to the steps (3-2-6) - (3-2-7) until the left and right end point numbers of the determined last lead reach the set values, namely the left end point number is equal to 4, and the right end point number meets one of the following conditions:
if the last lead is the first type of lead, the number of the right end point is equal to n, namely: j is n, wherein j is the right end point number;
if the last lead is the second type lead, the right end point number satisfies: j +1 ═ m, where j is its right end point number;
if the last lead is a third lead, the right end point number is equal to m, namely: j is m, wherein j is the right end point number.
And (3-2-9) dividing the top surface into a plurality of quadrilateral areas and determining corresponding partition modes according to the determined lead types.
Step (4), aiming at each partition mode, optimizing the vertex coordinates of each quadrilateral area by using the average mass of each quadrilateral area as an optimization target except for each vertex on the top surface and adopting a fruit fly algorithm to optimize the vertex coordinates so as to obtain the maximum value of the average mass of each quadrilateral area and the vertex coordinates corresponding to each quadrilateral area in the partition mode;
referring to fig. 3, fig. 3 is a flowchart for optimizing the average quality of the quadrilateral area by using the drosophila algorithm according to the embodiment of the present invention, which includes the following steps:
initializing the fruit fly population scale, population iteration times and fruit fly flying radius parameters;
step (4-2), obtaining linear equations of all sides of the top surface according to coordinates of all corner points of the polygonal top surface; the method comprises the following steps:
let two adjacent corner coordinates be (x)1,y1) And (x)2,y2) Then, the equation of the straight line formed by the two connecting lines is:
ax+by+c＝0 (1)
in the formula: a. b and c respectively represent coefficients of a linear equation, and the calculation formula is as follows:
wherein, formula 2 is a formula for calculating each coefficient of the equation when the slope of the straight line exists, and formula 3 is a formula for calculating each coefficient of the equation when the slope of the straight line does not exist.
Step (4-3), giving the coordinates of the individual edge points and the individual inner points of the primary fruit flies, and respectively distributing the coordinates at random positions inside the side line and the top surface of the top surface;
wherein: the coordinates of the edge points of the individual drosophila melanogaster are given by the following formula:
wherein: formula (4) is a formula for calculating the coordinates of the edge points when the slope of the line where the edge points are located exists, and formula (5) is a formula for calculating the coordinates of the edge points when the slope of the line where the edge points are located does not exist. (x)1,y1)、(x2,y2) As coordinates of two adjacent corner points, (x)3,y3) The coordinates of the odd-numbered edge points on the boundary line between the two adjacent corner points are (x)4,y4) Random () is [0,1] for even numbered edge point coordinates on the edge]The random numbers a, b, and c are coefficients of 0 in the edge line equation ax + by + c obtained in step (4-2).
The individual internal point coordinates of the primary drosophila are given by:
in the formula: (x, y) is the coordinates of the interior point, xmax、xminAnd ymax、yminRespectively, the maximum value and the minimum value of the horizontal and vertical coordinates of each corner point of the polygon top surface, and random]The random number of (2).
Step (4-4), calculating the average mass value of the quadrilateral area corresponding to the individual drosophila melanogaster of the first generation; the method for calculating the average quality value of the quadrilateral area comprises the following steps:
(1) the numbers of all vertexes of the ith quadrangle are 1, 2, 3 and 4 in sequence, the vertical coordinates of all vertexes are 0, and the mixed products a, b and c are calculated according to the following relational expressions:
in the formula: each vector is a three-dimensional vector.
(2) And judging the quadrilateral type according to the values of the obtained mixed products a, b and c:
if a is greater than 0, b is greater than 0, and c is less than 0, the quadrangle is a convex quadrangle;
if a >0, b <0, c <0 or a >0, b >0, c >0 or a <0, b >0, c <0 or a <0, b <0, then the quadrilateral is a concave quadrilateral;
if a is greater than 0, b is less than 0, c is greater than 0 or a is less than 0, b is greater than 0, c is greater than 0, then the four vertex connecting lines are crossed;
(3) from the quadrilateral type obtained above, its quality value is determined using the following relation:
in the formula: x and y are self-set penalty coefficientsAnd y is<x<0，JRThe ratio of the Jacobian determinant value minimum value and the Jacobian determinant value maximum value corresponding to each integral point of the quadrangle is as follows:
in the formula: | J-minIs the minimum value of Jacobian determinant corresponding to each integral point of the quadrangle, | JmaxThe maximum value of the Jacobian determinant corresponding to each integral point of the quadrangle is obtained by calculating the Jacobian determinant corresponding to each integral point of the quadrangle from the coordinates of each vertex of the quadrangle, and the calculation formula is as follows:
|J|1＝(x2-x1)(y4-y1)-(x4-x1)(y2-y1) (12)
|J|2＝(x3-x2)(y1-y2)-(x1-x2)(y3-y2) (13)
|J|3＝(x4-x2)(y2-y3)-(x2-x3)(y4-y3) (14)
|J|4＝(x1-x4)(y3-y4)-(x3-x4)(y1-y4) (15)
in the formula: x is the number of1-x4Is the abscissa, y, of each vertex of the quadrilateral1-y4The ordinate of each vertex of the quadrilateral.
Step (4-5), comparing the average mass values of quadrilateral areas corresponding to the individual drosophila melanogaster of the first generation, and reserving the maximum value and the coordinates of the corresponding inner point and edge point;
step (4-6), endowing the next generation of fruit fly individual inner point and edge point coordinates, and respectively distributing the coordinates at random positions in a circle with the reserved inner point and edge point as the center of the circle and the flying radius of the fruit fly as the radius; wherein:
the calculation formula of the coordinates of the internal points of the next generation of fruit flies is as follows:
in the formula: (x, y) are coordinates of the inner point of the next generation of fruit flies, neidian _ axis [0] and neidian _ axis [1] are respectively the horizontal coordinate and the vertical coordinate of the inner point reserved in the previous step, R is the flying radius of the fruit flies, and random.
The calculation formula of the next generation of individual edge point coordinates of the fruit flies is as follows:
in the formula: (x, y) are coordinates of edge points of the next generation of fruit flies, and binary _ axis [0] and binary _ axis [1] are respectively the horizontal coordinates and vertical coordinates of the edge points reserved in the previous step, R is the flying radius of the fruit flies, and random.
Step (4-7), calculating the average mass of the quadrilateral area corresponding to each drosophila individual in the step (4-6), wherein the method for calculating the average mass value of the quadrilateral area is the same as that in the step (4-4);
step (4-8), comparing the average quality of the quadrilateral areas corresponding to the fruit fly individuals to obtain the maximum value and the coordinates of the corresponding inner points and side points;
step (4-9), comparing the maximum value of the average quality of the quadrilateral area obtained in the step (4-8) with the maximum value of the average quality of the quadrilateral area reserved last time, and reserving the larger average quality value of the quadrilateral area and the corresponding coordinates of the inner point and the edge point;
step (4-10), repeatedly executing steps (4-6) - (4-9) until the number of operation times reaches the number of population iteration times;
and (4-11) obtaining the final average mass maximum value of the quadrilateral area and the coordinates of the corresponding inner point and edge point.
Step (5), comparing the average mass maximum values under various partition modes to obtain the partition mode corresponding to the maximum value and the vertex coordinates of each quadrilateral area;
and (6) dividing the rotor guide bar model into a plurality of cylindrical models with quadrangular top surfaces according to the optimal partition mode obtained in the step (5), and performing structured grid division on each cylindrical model by using a sweeping method to obtain an optimal structured grid division result of the rotor guide bar model.
Referring to fig. 4, a flow chart for performing structured meshing on each columnar model by using a sweep method according to an embodiment of the present invention includes the following steps:
step (6-1), dividing the top surface into a plurality of quadrilateral areas according to the partition mode obtained in the step (5), and dividing the rotor conducting bar model into cylindrical models with a corresponding number of quadrilateral top surfaces according to the obtained quadrilateral areas;
step (6-2), determining the initial grid size of each columnar model, specifically as follows:
in the formula: v is the initial grid size of each columnar model, S is the area of the top surface, and i is the number of quadrilateral areas divided by the top surface;
step (6-3), performing meshing on each columnar model by using a sweeping method according to the initial mesh size determined in the step (6-2);
step (6-4), carrying out thermal analysis on the finite element model subjected to grid division to obtain the thermal distribution of each columnar model, and taking the temperature of any point on the model as a value to be compared;
step (6-5), reducing the grid to half of the size of the grid at the previous time, and then carrying out grid division on each columnar model by using the same sweeping method as the step (6-3);
step (6-6), carrying out thermal analysis on the finite element model subjected to meshing in the step (6-5) to obtain a temperature value at the same point as that in the step (6-4);
step (6-7), comparing the temperature value obtained in step (6-6) with the temperature value of the same point obtained in the last thermal analysis to obtain a difference value △ Ti：
△Ti＝|Ti-T(i-1)| (19)
In the formula: t isiThe temperature value T of a certain point on the model obtained by the thermal analysis(i-1)The temperature value of the same point on the model obtained by the last thermal analysis is obtained;
step (6-8), judging the temperature deviation △ T obtained in the step (6-7)iWhether the current is within a preset threshold range, namely:
△Ti≤△TM(20)
in the formula, △ TMIs a temperature deviation of △ TiIs set to the preset threshold value.
If the temperature deviation is △ TiIf the preset threshold value is within the range, entering the next step, otherwise, returning to the step (6-5);
and (6-9) taking the obtained meshing result as the optimal structured meshing result of each columnar model.
The invention takes an alternating current motor with the model number of Y100L2-4 as an example, and the implementation steps of the invention are explained in detail. Referring to fig. 5, a dimension diagram of a top surface of a rotor bar of a Y100L2-4 ac motor according to an embodiment of the present invention, the top surface being hexagonal, and in combination with the dimension of the diagram, the implementation steps of the present invention are as follows:
step 3, adding a quadrangle into the top surface of the model at will, leading lines to each vertex of the top surface or two points randomly selected on each side of the top surface through each vertex of the quadrangle respectively, so as to divide the top surface into a plurality of quadrangle areas and obtain all partition modes for dividing the top surface into a plurality of quadrangle areas;
step 4, aiming at each partition mode, optimizing the vertex coordinates of each quadrilateral area by using the average mass of each quadrilateral area as an optimization target except for each vertex of the top surface and adopting a drosophila algorithm to obtain the maximum value of the average mass of each quadrilateral area and the vertex coordinates corresponding to each quadrilateral area in the partition mode;
the relevant parameters of the fruit fly algorithm are set as follows: the fruit fly population scale is 5000, the maximum iteration number is 300, and the flying radius R of the fruit flies is 0.2; the optimization process is shown in fig. 7. It can be seen that: after the number of iterations reaches about 75, the average mass of each quadrilateral area has substantially reached its maximum.
And 6, dividing the rotor guide bar model into a plurality of columnar models with quadrangular top surfaces according to the optimal partition mode obtained in the step 5, and performing structured grid division on each columnar model by using a sweeping method to obtain an optimal structured grid division result of the rotor guide bar model. The resulting optimal structured meshing scheme is shown in fig. 9.
In addition, the alternating current motor rotor conducting bar thermal analysis model structured grid optimization division method provided by the invention is compared with the traditional grid division method, and relevant results are shown in table 1.
TABLE 1
| Average mass | Lowest qualityMeasurement of | |
| Traditional mesh partitioning method | 0.91216 | 0.3115 |
| Grid optimization division method | 0.93687 | 0.8556 |
It can be seen that: compared with the traditional grid division method, the optimization method provided by the invention obviously improves the minimum grid quality and the average quality of the whole grid, thereby effectively improving the thermal analysis precision of the rotor conducting bar of the alternating current motor.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments are still modified, or some or all of the technical features are equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A structured grid optimization division method of an alternating current motor rotor conducting bar thermal analysis model is characterized by comprising the following steps: the method comprises the following steps:
(1) selecting the polygonal top surface of the rotor guide bar model as a grid division area, and establishing a rectangular coordinate system with any vertex of the top surface as a coordinate origin on the top surface of the polygonal top surface to obtain a rectangular coordinate of each vertex of the top surface;
(2) respectively numbering the top points and the two points randomly selected on the sides of the top surface in sequence by taking the top surface coordinate origin as a starting point;
(3) a quadrangle is arbitrarily added in the top surface of the model, leads are respectively led to each vertex of the top surface or two points arbitrarily selected on each edge of the top surface through each vertex of the quadrangle, so that the top surface is divided into a plurality of quadrangle areas, and all partition modes of dividing the top surface into a plurality of quadrangle areas are obtained;
(4) aiming at each partition mode, the vertex coordinates of each quadrilateral area are taken as an optimization object, the average mass of each quadrilateral area except the top vertices is taken as an optimization target, and the optimization is carried out by adopting a drosophila algorithm so as to obtain the maximum value of the average mass of each quadrilateral area and the vertex coordinates corresponding to each quadrilateral area in the partition mode;
(5) comparing the average quality maximum values under various partition modes to obtain the partition mode corresponding to the maximum value and the vertex coordinates of each quadrilateral area;
(6) and (5) dividing the rotor guide bar model into a plurality of columnar models with quadrangular top surfaces according to the optimal partition mode obtained in the step (5), and performing structured grid division on each columnar model by using a sweeping method to obtain an optimal structured grid division result of the rotor guide bar model.
2. The method for optimally dividing the structured grid of the thermal analysis model of the alternating current motor rotor conducting bar according to claim 1, is characterized in that: in the step (2), the top surface vertexes and the two points arbitrarily selected on the top surface sides are numbered according to the following rules:
(2-1) calling each vertex of the top surface as an angular point, and calling two points arbitrarily selected on each edge of the top surface as edge points;
(2-2) numbering each angular point and each side point respectively;
(2-3) numbering other angular points in sequence in a clockwise direction or an anticlockwise direction by taking the angular point where the origin of coordinates is located as a No. 1 angular point;
(2-4) numbering each side point according to the same winding direction of the angular point numbers, taking the first side point encountered by the angular point No. 1 in the corresponding winding direction as the side point No. 1, and numbering the rest side points in sequence.
3. The method for optimally dividing the structured grid of the thermal analysis model of the alternating current motor rotor conducting bar according to claim 1, is characterized in that: in the step (3), a quadrangle is arbitrarily added to the top surface of the model, and the numbering rule of each vertex of the quadrangle is as follows:
(3-1-1) designating each vertex of the quadrangle as an interior point;
(3-1-2) any one inner point is an inner point No. 1, and all the inner points are numbered according to the same winding direction of the angular point numbers.
4. The method for optimally dividing the structured grid of the thermal analysis model of the alternating current motor rotor conducting bar according to claim 1, is characterized in that: in the step (3), the top surface is divided into a plurality of quadrilateral areas, and the specific rule is as follows:
(3-2-1) for convenience, connecting lines of the inner points and the angular points, the inner points and the odd-numbered side points, and the inner points and the even-numbered side points are respectively referred to as first-type, second-type, and third-type lead lines, wherein the inner points are referred to as left end points of the three-type lead lines, and the other end points are referred to as right end points of the lead lines;
(3-2-2) setting the number of corner points of the top surface of the polygon as n and the number of side points as m, and comprising: m is 2 n;
(3-2-3) determining a first lead of the partition, i.e., an initial lead; the initial lead is a connecting line of a No. 1 inner point and a No. 1 angular point or a connecting line of a No. 1 inner point and a No. 1 side point;
(3-2-4) determining a second lead according to the initial lead type, the quadrilateral partition mode and the endpoint number increasing rule:
if the initial lead is a connecting line between the inner point No. 1 and the angular point No. 1, the second lead includes the following four conditions: the No. 1 inner point is connected with the No. 3 edge point, the No. 1 inner point is connected with the No. 3 corner point, the No. 2 inner point is connected with the No. 1 edge point, and the No. 2 inner point is connected with the No. 2 corner point;
if the initial lead is a connection line between the No. 1 inner point and the No. 1 side point, the second lead comprises the following four conditions: the No. 1 inner point is connected with the No. 3 edge point, the No. 1 inner point is connected with the No. 3 corner point, the No. 2 inner point is connected with the No. 2 edge point, and the No. 2 inner point is connected with the No. 2 corner point;
(3-2-5) determining a third lead according to the second lead type determined in the step (3-2-4) and the quadrilateral partition mode and endpoint number increasing rule, wherein the method comprises the following 5 cases:
if the second lead is the first type of lead and the second lead and the initial lead are connected to the same inner point, that is, the second lead is a connection line between the number 1 inner point and the number 3 angular point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 5 edge point, and the No. 2 inner point is connected with the No. 4 corner point;
if the second lead is the first type of lead and the second lead is connected to the initial lead at a different inner point, i.e. the second lead is a connection line between the number 2 inner point and the number 2 angular point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 5 edge point, the No. 2 inner point is connected with the No. 4 corner point, the No. 3 inner point is connected with the No. 3 edge point, and the No. 3 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at the same inner point, namely the second lead is the connection line of the No. 1 inner point and the No. 3 side point, the third lead has the following two conditions: the No. 2 inner point is connected with the No. 4 edge point, and the No. 2 inner point is connected with the No. 3 corner point;
if the second lead is the second type lead and the second lead is connected with the initial lead at different inner points, namely the second lead is a connection line of the No. 2 inner point and the No. 1 side point, the third lead has the following four conditions: the No. 2 inner point is connected with the No. 3 edge point, the No. 2 inner point is connected with the No. 3 corner point, the No. 3 inner point is connected with the No. 2 edge point, and the No. 3 inner point is connected with the No. 2 corner point;
if the second lead is the third type lead and the second lead is connected with the initial lead at different inner points, that is, the second lead is a connection line between the No. 2 inner point and the No. 2 side point, the third lead has the following three conditions: the No. 2 inner point is connected with the No. 3 edge point, the No. 2 inner point is connected with the No. 3 corner point, and the No. 3 inner point is connected with the No. 2 corner point;
(3-2-6) determining the next lead according to the last lead type determined in the previous step, the quadrilateral partition mode and the endpoint number increasing rule, wherein the method comprises the following 5 cases:
if the last determined lead is the first type of lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (2j-1) side point, and the (i +1) inner point is connected with the (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the first type of lead and the last determined lead is connected to the previous lead at a different interior point, the next lead has the following four conditions: the number i inner point is connected with the number (2j +1) edge point, the number i inner point is connected with the number (j +2) corner point, the number (i +1) inner point is connected with the number (2j-1) edge point, and the number (i +1) inner point is connected with the number (j +1) corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last determined lead is the second type lead and the last determined lead is connected to the same inner point as the previous lead, the next lead has the following two conditions: the (i +1) inner point is connected with the (j +1) side point, and the (i +1) inner point is connected with the (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the determined last lead is the second type lead and the determined last lead is connected to the previous lead at a different inner point, the next lead has the following four conditions: the number i inner point is connected with the number (j +2) edge point, the number i inner point is connected with the number (j +5)/2 corner point, the number (i +1) inner point is connected with the number (j +1) edge point, and the number (i +1) inner point is connected with the number (j +3)/2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
if the last lead is determined to be the third type of lead, the next lead has the following three conditions: the number i inner point is connected with the number (j +1) side point, the number i inner point is connected with the number (j + 4)/number 2 corner point, and the number (i +1) inner point is connected with the number (j + 2)/number 2 corner point; i and j are respectively the left end point number and the right end point number of the last determined lead wire;
(3-2-7) judging whether the endpoint number of the next lead determined in the step (3-2-6) has an overrun condition, if the endpoint number has one of the following conditions, judging that the endpoint number is overrun:
(a) the number of the left endpoint is greater than 4;
(b) if the right end point is an angular point, the number of the end point is greater than n;
(c) if the right end point is an odd-numbered side point, and the end point number is greater than (m-1);
(d) if the right endpoint is an even number of side points, and the endpoint number is more than m;
if any one of the conditions occurs in the determined end point number of the next lead, deleting the lead;
(3-2-8) determining the next lead according to the steps (3-2-6) - (3-2-7) until the left and right end point numbers of the determined last lead reach the set values, namely the left end point number is equal to 4, and the right end point number meets one of the following conditions:
if the last lead is the first type of lead, the number of the right end point is equal to n, namely: j is n, wherein j is the right end point number;
if the last lead is the second type lead, the right end point number satisfies: j +1 ═ m, where j is its right end point number;
if the last lead is a third lead, the right end point number is equal to m, namely: j is m, wherein j is the right end point number;
(3-2-9) dividing the top surface into a plurality of quadrangular areas and determining the corresponding partition modes according to the determined lead types.
5. The method for optimally dividing the structured grid of the thermal analysis model of the alternating current motor rotor conducting bar according to claim 1, is characterized in that: the average quality of the quadrilateral area is optimized by adopting a drosophila algorithm in the step (4), and the method comprises the following specific steps:
(4-1) initializing the fruit fly population scale, population iteration times and fruit fly flying radius parameters;
(4-2) obtaining a linear equation of each side of the top surface according to the coordinates of each corner point of the polygonal top surface;
(4-3) endowing the individual side point and inner point coordinates of the primary fruit fly to distribute the coordinates at random positions of the side line of the top surface and the inside of the top surface respectively;
(4-4) calculating the average mass value of the quadrilateral area corresponding to the individual drosophila melanogaster of the initial generation;
(4-5) comparing the average mass values of quadrilateral areas corresponding to the individual drosophila melanogaster of the first generation, and reserving the maximum value and the coordinates of the corresponding inner point and edge point;
(4-6) endowing the next generation of fruit fly individual inner point and edge point coordinates, and respectively distributing the coordinates at random positions in a circle with the reserved inner point and edge point as the circle center and the fruit fly flying radius as the radius;
(4-7) calculating the average mass of the quadrilateral area corresponding to each drosophila individual in the step (4-6);
(4-8) comparing the average quality of the quadrilateral areas corresponding to the fruit fly individuals to obtain the maximum value and the coordinates of the corresponding inner points and side points;
(4-9) comparing the maximum value of the average quality of the quadrilateral area obtained in the step (4-8) with the maximum value of the average quality of the quadrilateral area reserved last time, and reserving the larger average quality value of the quadrilateral area and the corresponding coordinates of the inner point and the edge point of the quadrilateral area;
(4-10) repeating the steps (4-6) - (4-9) until the number of operation times reaches the number of population iterations;
and (4-11) obtaining the final average mass maximum value of the quadrilateral area and the corresponding coordinates of the inner point and the edge point.
6. The method for optimally dividing the structured grid of the alternating current motor rotor conducting bar thermal analysis model according to claim 5, is characterized in that: the average mass calculation method for the quadrilateral area in the step (4-4) or the step (4-7) is specifically as follows:
in the formula: q _ average represents the average quality of each quadrilateral area in a partition mode, l represents the number of quadrilateral areas in the partition mode, and q represents the average quality of each quadrilateral area in the partition modeiRepresenting the quality value of the ith quadrilateral area.
7. The method for optimally dividing the structured grid of the alternating current motor rotor conducting bar thermal analysis model according to claim 6, is characterized in that: the quality calculation method of the quadrilateral area specifically comprises the following steps:
(1) the numbers of all vertexes of the ith quadrangle are 1, 2, 3 and 4 in sequence, the vertical coordinates of all vertexes are 0, and the mixed products a, b and c are calculated according to the following relational expressions:
in the formula: all the vectors are three-dimensional vectors;
(2) and judging the quadrilateral type according to the values of the obtained mixed products a, b and c:
if a is greater than 0, b is greater than 0, and c is less than 0, the quadrangle is a convex quadrangle;
if a >0, b <0, c <0 or a >0, b >0, c >0 or a <0, b >0, c <0 or a <0, b <0, then the quadrilateral is a concave quadrilateral;
if a is greater than 0, b is less than 0, c is greater than 0 or a is less than 0, b is greater than 0, c is greater than 0, then the four vertex connecting lines are crossed;
(3) from the quadrilateral type obtained above, its quality value is determined using the following relation:
in the formula: x and y are self-set penalty coefficients<x<0，JRThe ratio of the Jacobian determinant value minimum value and the Jacobian determinant value maximum value corresponding to each integral point of the quadrangle is as follows:
in the formula: | J-minIs the minimum value of Jacobian determinant corresponding to each integral point of the quadrangle, | JmaxThe maximum value of the Jacobian determinant corresponding to each integral point of the quadrangle is obtained by calculating the Jacobian determinant corresponding to each integral point of the quadrangle from the coordinates of each vertex of the quadrangle, and the calculation formula is as follows:
|J|1＝(x2-x1)(y4-y1)-(x4-x1)(y2-y1) (7)
|J|2＝(x3-x2)(y1-y2)-(x1-x2)(y3-y2)(8)
|J|3＝(x4-x2)(y2-y3)-(x2-x3)(y4-y3) (9)
|J|4＝(x1-x4)(y3-y4)-(x3-x4)(y1-y4) (10)
in the formula: x is the number of1-x4Is the abscissa, y, of each vertex of the quadrilateral1-y4The ordinate of each vertex of the quadrilateral.
8. The method for optimally dividing the structured grid of the thermal analysis model of the alternating current motor rotor conducting bar according to claim 1, is characterized in that: in the step (6), the structural grid division is performed on each columnar model by using a sweeping method, and the specific method is as follows:
(6-1) dividing the top surface into a plurality of quadrilateral areas according to the partition mode obtained in the step (5), and dividing the rotor guide bar model into cylindrical models with a corresponding number of quadrilateral top surfaces according to the quadrilateral areas;
(6-2) determining the initial grid size of each columnar model, wherein the initial grid size is as follows:
in the formula: v is the initial grid size of each columnar model, S is the area of the top surface, and i is the number of quadrilateral areas divided by the top surface;
(6-3) meshing each columnar model by using a sweeping method according to the initial grid size determined in the step (6-2);
(6-4) carrying out thermal analysis on the finite element model subjected to meshing to obtain the thermal distribution of each columnar model, and taking the temperature of any point on the model as a value to be compared;
(6-5) reducing the grid to half of the size of the grid at the previous time, and meshing each columnar model by using the same sweeping method as the step (6-3);
(6-6) carrying out thermal analysis on the finite element model subjected to meshing in the step (6-5) to obtain a temperature value at the same point as that in the step (6-4);
(6-7) comparing the temperature value obtained in the step (6-6) with the temperature value of the same point obtained in the last thermal analysis to obtain a difference value delta Ti：
ΔTi＝|Ti-T(i-1)| (12)
In the formula: t isiThe temperature value T of a certain point on the model obtained by the thermal analysis(i-1)The temperature value of the same point on the model obtained by the last thermal analysis is obtained;
(6-8) judging the temperature deviation DeltaTiWhether the current is within a preset threshold range, namely:
ΔTi≤ΔTM(13)
in the formula: delta TMIs a temperature deviation Delta TiA preset threshold value of;
if the temperature deviation DeltaTiIf the preset threshold value is within the range, entering the next step, otherwise, returning to the step (6-5);
and (6-9) taking the obtained meshing result as an optimal structured meshing result for each columnar model.
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