WO2007099640A1

WO2007099640A1 - Electromagnetic field distribution calculation method, electromagnetic field distribution calculation device, and electromagnetic field distribution calculation program

Info

Publication number: WO2007099640A1
Application number: PCT/JP2006/304134
Authority: WO
Inventors: Kengo Sugahara; Kiyoshi Yoda
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2006-03-03
Filing date: 2006-03-03
Publication date: 2007-09-07

Abstract

It is possible to provide an electromagnetic field distribution calculation method capable of performing a large-scale electromagnetic distribution calculation by using a small amount of calculation resource. Furthermore, it is possible to provide an electromagnetic field distribution calculation device and an electromagnetic field distribution calculation program. The electromagnetic field calculation method divides a metal structure surface divided into a plurality of elements into a plurality of element blocks, sets currents of unknown values vertical to common sides between the elements, and block-divides the unknown-value currents into a current block n belonging only to the respective element blocks and a current block m collecting the unknown-value currents flowing between the respective element blocks into one, thereby creating a block matrix equation. Furthermore, when solving the block matrix equation, the block repletion method is used for calculating a term concerning only the current block n and the direct method is used for calculating a term concerning the current block m. According to the obtained unknown-value current of each current block, an electromagnetic field distribution around the metal structure is calculated.

Description

Specification

Electromagnetic field distribution calculation method, electromagnetic field distribution calculation device, and electromagnetic field distribution calculation program

Technical field

The present invention relates to a calculation method for calculating an electromagnetic field distribution when an electromagnetic wave transmitted from an electromagnetic wave source is scattered by a metal structure (scattering body) in the vicinity thereof. For example, the present invention relates to a calculation method in an automobile Generated as a result of calculating the electromagnetic wave distribution when the electromagnetic wave transmitted by the transmitting antenna is scattered or reflected by the body structure, or as a result of the eddy current flowing through the body structure of the electromagnetic wave transmitted by the transmitting antenna in the car. It relates to a method of calculating the electromagnetic wave distribution. The present invention also relates to an apparatus using this calculation method and an electromagnetic field distribution calculation program.

Background art

[0002] In the late 1960s, Harrington used the method of moments for the numerical solution of the field integral equation method, and concretely and theoretically organized analysis methods for electromagnetic wave scattering problems. In the case of analysis with a specified frequency, the integral equation method is the smallest of the many numerical methods for solving electromagnetic waves, and is the most accurate method with the most accurate number of unknowns. In the analysis of microstrip type microwave integrated circuits and antennas, an integral equation is normally created with the current on the patch as an unknown, and the integral equation is directly solved for analysis (see Non-Patent Document 1, for example). o

[0003] However, in this method, since the matrix equation becomes a complex dense matrix equation, when the size of the scattering problem is large, such as the scattering problem of electromagnetic waves from a car, a lot of computer memory and a lot of calculation time are required. Consume. For example, to store a 10,000-element complex dense matrix in the computer's memory, 1.6 GByte of memory is required. On the other hand, the size of available memory is limited (2 GByte to 4 GByte) in the general-purpose 32-bit computers. Therefore, the conventional method, that is, the method of directly solving the created matrix equation (hereinafter referred to as the direct method), cannot perform large-scale calculation of tens of thousands of elements.

One way to solve this problem is to configure the circuit in a microwave circuit. There are proposed methods (B1 ock Jacobi method, Block Gauss Seidel method, Block SOR method, etc.) that divide into blocks according to structure, perform iterative calculations, and solve matrix equations efficiently (for example, Non-Patent Document 2) See also.) ₀

[0004] Non-Patent Document 1: S. M. Rao, D. A. Wilton and A. W. Glisson, IEEE Trans.

Antennas and Propaget., Vol. 30, No. 3, pp. 409—418, May 1982. Non-Patent Document 2: S. Ooms, DD Zutter, DIAKOPTICS AND THE MUL TILEVEL MOMENTS METHOD FOR PLANAR CIRCUITS, IEEE MTT— S International Microwave Symposium Digest Vol. 39 No. 3, 1997 (P. 1803, P. 1806)

Disclosure of the invention

Problems to be solved by the invention

[0005] However, when the above method is applied to a general scatterer, not limited to the microwave integrated circuit, it is useful when the number of connection sides between blocks is 1 or less. When the blocks are connected by two or more sides, it is clear that the iterative calculation does not converge and the correct electromagnetic field distribution cannot be obtained, and the above method cannot be applied.

[0006] The present invention has been made to solve the problem, and in analyzing the electromagnetic field distribution, the field integral equation moment method is applied and the large-scale problem in the field integral equation is solved. The object of the present invention is to provide an electromagnetic field distribution calculation method capable of calculating a large-scale electromagnetic field distribution with a small amount of computer qualities.

It is another object of the present invention to provide an electromagnetic field distribution calculation device and an electromagnetic field distribution calculation program capable of calculating a large-scale electromagnetic field distribution with a small amount of computer qualities.

Means for solving the problem

[0007] In the electromagnetic field distribution calculation method according to the present invention, a first step of dividing the surface of the metal structure into elements having a plurality of minute areas, a shared side between the elements for the plurality of divided elements The second step of setting the unknown current perpendicular to the shared edge, the third step of dividing the plurality of elements into N—one element block, the plurality of the set The unknown current is grouped separately for each element block, and 4th step to block-divide N into 1 current block n that belongs only to each element block and current block m that combines unknown current flowing between each element block into one block For each current block, the fifth step of creating a block matrix equation by the field integral equation moment method, when calculating the block matrix equation, it is necessary to calculate the term related to only N—one current block n. Uses the block iteration method, the direct method is used to calculate the term related to the current block m, the sixth step of calculating the unknown current value of all the current blocks, and the obtained unknown number of each current block Based on the current value, it has a seventh step to calculate the electromagnetic field distribution around the metal structure.

[0008] In addition, the electromagnetic field distribution calculation apparatus according to the present invention provides an input means for inputting element data on the surface of a metal structure divided into a plurality of elements having a minute area force, and for the divided plurality of elements. An unknown current setting means for detecting a shared edge between elements and setting an unknown current perpendicular to the shared edge, and an element block division for dividing the plurality of elements into N—a plurality of element blocks Means, a plurality of set unknown currents are grouped separately for each element block, and N—one current block n belonging only to each element block, and the unknown current flowing between each element block Current block dividing means that divides the current block into one block, m, and the block matrix equation for each current block divided into N blocks by the electric field integral equation moment method. Block matrix equation construction means, when solving the block matrix equation, the block iteration method is used to calculate the term related only to the N current block n, and the term related to the current block m is calculated. The solution method for calculating the unknown current values of all current blocks using the direct method and the electromagnetic field distribution calculation means for calculating the electromagnetic field distribution around the metal structure based on the obtained unknown current values of each current block It is equipped with.

[0009] In addition, the electromagnetic field distribution calculation program according to the present invention provides a first step of dividing the surface of the metal structure into a plurality of elements each having a small area force. The second step is to set the unknown current perpendicular to the shared side, and the third step to block the multiple elements into N—multiple element blocks. Multiple unknown currents are grouped separately for each element block. The fourth step of dividing the block into N—one current block n belonging only to each element block and a current block m in which unknown currents flowing between the element blocks are combined into one, N For each current block divided into blocks, the fifth step of creating a block matrix equation by the electric field integral equation moment method, when solving the block matrix equation, only the N-1 current block n The block iteration method is used to calculate the related terms, the direct method is used to calculate the terms related to the current block m, the sixth step of calculating the unknown current values of all the current blocks, and each obtained Based on the unknown current value of the current block, the seventh step of calculating the electromagnetic field distribution around the metal structure is executed.

The invention's effect

[0010] In the electromagnetic field distribution calculation method, electromagnetic field distribution calculation apparatus, and electromagnetic field distribution calculation program of the present invention, the surface of the metal structure is divided into a plurality of metal elements having a minute area force, and a plurality of metal structures are provided. The electromagnetic field distribution is calculated for each block structure, but when the metal structure is divided into block structures, each block is divided so that the number of sides of the metal elements shared by each divided structure is as small as possible. In addition to creating a matrix equation for, and efficiently solving the matrix equation using the direct method and the block iteration method, the electromagnetic field distribution for any metal structure can be calculated with little computer quality.

Brief Description of Drawings

FIG. 1 is a flowchart showing a method for calculating an electromagnetic field distribution in an electromagnetic wave scatterer according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an electromagnetic field distribution calculation method (step S1) according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an electromagnetic field distribution calculation method (step S3) according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining an electromagnetic field distribution calculation method (step S4) according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining an electromagnetic field distribution calculation method (step S5) according to the first embodiment of the present invention. It is.

FIG. 6 is a diagram for explaining an electromagnetic field distribution calculation method (step SI) according to the second embodiment of the present invention.

FIG. 7 is a diagram for explaining an electromagnetic field distribution calculation method (step S 3) according to the second embodiment of the present invention.

FIG. 8 is a diagram for explaining an electromagnetic field distribution calculation method (step S 4) according to the second embodiment of the present invention.

FIG. 9 is a diagram for explaining an electromagnetic field distribution calculation method (step S5) according to the second embodiment of the present invention.

FIG. 10 is a diagram for explaining an electromagnetic field distribution calculation method (step S1) according to the third embodiment of the present invention.

FIG. 11 is a diagram for explaining an electromagnetic field distribution calculation method (step S5) according to the third embodiment of the present invention.

FIG. 12 is a block diagram showing an electromagnetic field distribution calculating apparatus according to Embodiment 3 of the present invention. Explanation of symbols

[0012] 1 automotive metal element configuration data, 2 element data input means, 3 unknown current setting means, 4 metal element block division means, 5 unknown current block division means, 6 block matrix equation construction means, 7 matrix Equation solving means, 8 electromagnetic field distribution calculating means, 10 metal plates, 20 metal structures, A, B, C metal element blocks.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1.

Fig. 1 (a) is a flowchart showing the electromagnetic field distribution calculation method for the electromagnetic wave scatterer according to Embodiment 1 of the present invention, and Fig. 1 (b) is an electric field integral equation moment method ( This is a flowchart showing a method of calculating the electromagnetic field distribution in the electromagnetic field scatterer using the conventional moment method).

In the present invention, in calculating the electromagnetic field distribution, the block division and the block iteration method are applied, the block division method, and the direct method when solving the integral equation and the block iteration method are applied. By devising, calculation time, memory used It is possible to solve the large-scale problem by reducing the computational resources.

As a specific description of the flowchart of FIG. 1, consider the problem of high-frequency electromagnetic field scattering from a square metal plate.

First, in step S1, as shown in FIG. 2, the metal flat plate 10 which is an electromagnetic wave scatterer is divided into a plurality of triangular elements. In this example, it is divided into triangular elements, but there is also a conventional method of dividing into quadrilateral or polygonal elements. The present invention can also be applied to elements other than triangular elements as divided elements (same as the conventional method).

Next, in step S 2, the number of block divisions (N−1) is designated. Although the number of divisions varies depending on the scale of the problem, in order to obtain the effect of reducing the calculation time in a large-scale problem with tens of thousands of elements, the blocks are divided so that the elements in the block are about 3000 elements.

In this example, for clarity of explanation, consider dividing the 72 triangular elements into two blocks.

[0016] Next, in step S3, a side shared by the triangular elements is detected, and a current flowing perpendicularly to the side is set as an unknown (same as in the conventional method). Figure 3 shows the unknown current (arrow) set.

In this square metal plate example, there are 96 unknown currents I. In the conventional moment method, at step S60 in Fig. 1 (b), an impedance matrix Z of 96 X 96 is created based on these 96 unknown currents I, and a matrix equation ZI = V is created. In step S70, the matrix equation is solved by the direct method to obtain the current I.

In the present invention, the set unknown current is divided into blocks as shown below, and a block matrix equation is created for each divided current block.

That is, in step S4, the metal element is divided such that the number of unknown currents flowing only in each element block is almost the same and the number of unknown currents flowing between the element blocks is minimized. Optimization techniques (for example, “Numerical Recipes in C: The

The block division of metal elements is determined by the genetic algorithm (Genetic Algorithm method) published in Art of Scientific ComputmgJ ("William H. Press, Brian P. Flannery, Saul A. Teukolsky, William T. Vetterling)" Optimize To do.

In this example, the number of unknown currents is 96, and the minimum number of currents per block is limited to 40. When searching for the optimal division, the number of shared sides between element blocks is 6. Optimized. As shown in Fig. 4, the metal element is divided into two blocks, a white part (element block A) and a gray part (element block B).

[0018] Next, in step S5, a plurality of unknown currents set in step S3 belong only to each element block, and N—one current block n separately grouped for each element block. Then, the unknown current flowing between the element blocks is divided into current blocks m which are combined into one. That is, as shown in Fig. 5 (a), an unknown current belonging only to element block A is a current block (1), and as shown in Fig. 5 (c), an unknown current belonging only to element block B is a current block. (2) As shown in Fig. 5 (b), the unknown current flowing between element block A and element block B is defined as current block (3).

[0019] Next, in step S6, a matrix equation is created for each current block divided into N blocks by a method similar to the conventional moment method, and in step S7, this matrix equation is solved, and all currents are Calculate the unknown current value of the block. In the conventional moment method, as described above, the force to create one impedance matrix Z of 96 X 96 In this embodiment, when the matrix equation is created in step 6 above, the impedance matrix is 3 X Create a block matrix of 3 and the following block matrix equation.

[0020] [Equation 1]

11 Η2

<1)

^ '21 32

[0021] In this example, Z is a 45 X 45 matrix, Z is a 45 X 45 matrix, Z is a 45 X 6 matrix, Z

11 12 13

Is a 45 x 45 matrix, Z is a 45 x 45 matrix, Z is a 45 x 6 matrix, Z is a 6 x 45 matrix

21 22 23 31

, Z is a 6 x 45 matrix and Z is a 6 x 6 matrix. Note that I is an unknown current vector of 45 X 1.

32 33 1

Toll, I is an unknown current vector of 45 X 1, I is an unknown current vector of 6 X 1, and this

twenty three

It is a solution to be obtained by an equation. V is a voltage vector of 45 x 1, V is a voltage beta of 45 x 1 , V is a 6 x 1 voltage vector, which is that of an electromagnetic source with multiple triangular elements

Three

This is the voltage created at each side element. The voltage vector is created in the same way as the conventional moment method.

Next, a procedure for solving this matrix equation is shown.

In the present embodiment, as shown in FIG. 5, the unknown current is divided into a current block (1), a current block (2), and a current block (3). (3). By performing such block division, the interaction between the blocks is ignored as an initial value for the matrix related only to the current block (1) and the current block (2). Can be approximated. As a result, the interaction between current blocks other than the current block (3) is well known and can be corrected by the block iteration method (Block Jacobi method, Block Gauss Seidel method, Block SOR method). Become. Furthermore, for the matrix related to the current block (3), use the direct method to obtain a solution that considers the interaction between the current block (3) and each of the other current blocks (1) and (2). Can do. In other words, since the number of unknown currents is the smallest, even if the direct method is used, the calculation can be performed with a small amount of calculation. As a result, even when blocks are connected by two or more sides, the correct electromagnetic field distribution is obtained by using the minimum slow direct method and the fast block iteration method together. be able to.

[0023] The procedure is described in detail below.

Equation (1) can be written down as the following equations (2) and (3). This is a simple mathematical variant.

[0024] [Equation 2]

33 32. <2)

The computation cost (used memory, computation time) of the matrix operations is the one that calculates the inverse matrix. Lower the overall computational cost by improving the efficiency of computing the inverse matrix be able to.

(2) In Equation (3), there are the following four operations (Equations (4) to (7)) for calculating the inverse matrix.

[0026] [Equation 3]

2

[0027] Inverse matrix in equations (4) to (7)

[0028] [Equation 4]

[0029] is an inverse matrix of the impedance matrix related only to the current block (1) and the current block (2), and there is no interaction between the current block (1) and the current block (2). The block iteration method can be used to calculate equation (8). If the block iterative method can be used, the calculation cost can be reduced compared with the method of obtaining the normal inverse matrix. In addition, in the calculation of the inverse matrix of equation (6) including the term related to the current block (3), the number of sides connecting the blocks is 6, so the size of the matrix for calculating the inverse matrix is The calculation cost is 6 × 6, which is lower than the 96 × 96 inverse matrix when the conventional moment method is applied.

[0030] Specifically, the inverse matrix of equation (8) is calculated by the block iteration method, and from this, equations (4), (5), and (7) are calculated. Further, using the result of equation (4), the inverse matrix of equation (6) is calculated by the direct method. Obtained All current vectors I, I, I are calculated using the calculated results and equations (2) and (3).

one two Three

Find the unknown current value.

[0031] In step S8, an electromagnetic field at an arbitrary point can be calculated by calculating a green function for the obtained current value in the same manner as in the conventional moment method.

[0032] This method requires less calculation resources such as calculation time and used memory than the conventional moment method. In other words, in the conventional calculation method using only the direct method, when the number of unknown currents is N, the calculation amount is 0 (N ³ ), but in the method according to the present invention, the calculation amount is 0 (N ² ). Become. Therefore, the calculation time can be shortened depending on this. In addition, the memory used is 1Z4 in the case of the present embodiment in which the metal element is divided into two blocks, so that calculation resources can be saved.

Therefore, the calculation cost can be reduced by using the method of the present invention.

[0033] Embodiment 2.

FIG. 6 is a diagram in which the rectangular metal plate 10 according to the second embodiment is divided into triangular elements. For these triangular elements, the electromagnetic field distribution was calculated according to the flowchart in Fig. 1 (a). In the second embodiment, the number of block divisions (N-1) specified in step S2 is three. In step S3, as shown in Fig. 7, if the current on the shared side shared between the elements is set as the unknown current, there are 147 unknown currents. With the conventional moment method, an impedance matrix Z of 147 X 147 is created based on this unknown current, a matrix equation ZI = V is created, and this matrix equation is solved by the direct method to obtain the current I.

In this embodiment, in order to save calculation cost (used memory 'calculation time), the following block division is performed and the block matrix equation is created without directly creating the impedance matrix. That is, in step S4, as shown in FIG. 8, the triangular element is divided into three blocks: a left part (element block A), a central part (element block B), and a right part (element block C).

[0034] In step S5, the unknown current set in step S3 belongs only to each element block and is divided into N—one current block n separately for each element block, and each element described above. The unknown current flowing between the blocks is divided into current blocks _m that are combined into one block. That is, as shown in Fig. 9 (a), the unknown current belonging only to element block A is As shown in current block (1) and Fig. 9 (b), an unknown current belonging only to element block B is converted to an unknown current belonging only to element block C as shown in current block (2) and Fig. 9 (c). As shown in Fig. 9 (d), the unknown current flowing between element block A and element block B and the unknown current flowing between element block B and element block are Let it be the flow block (4).

[0035] Next, in step S6, a matrix equation is created for each current block divided into N blocks by the same method as the conventional moment method. In step S7, this matrix equation is solved, and all currents are Calculate the unknown current value of the block. However, in the present embodiment, a 4 × 4 block matrix is created as an impedance matrix, and the following block matrix equation is created.

[0036] [Equation 5]

[0037] In this example, Ζ is a 45X45 matrix, Ζ is a 45X45 matrix, Ζ is a 45X45 matrix,

11 12 13

Ζ 〖45 45 XI 2 row 歹 U 〖〖45 x 45 row 歹 U Z 〖45 x 45 row Z U Z 〖45 x 45

14 21 22 23

Matrix, Z is a 45X12 matrix, Z is a 45X45 matrix, Z is a 45X45 matrix, Z is 45

24 31 32 33

X45 matrix, Z is 45X12 matrix, Z is 12X45 matrix, Z is 12X45 matrix, Z

34 41 42 4 is a 12X45 matrix and Z is a 12X12 matrix. Note that I is an unknown current base of 45X 1.

3 44 1

Tuttle, I is an unknown current vector of 45 X 1, I is an unknown current vector of 45 X 1, I is 12

2 3 4

This is the unknown current vector of X1, which is the solution to be obtained from this equation. V 45X 1

1

Voltage vector, V is 45 x 1 voltage vector, V is 45 x 1 voltage vector, V is 12 x 1

2 3 4 These are the voltages generated by the electromagnetic wave source at each side element of the triangular elements. The method of creating the voltage vector is the same as the conventional moment method.

Next, a procedure for solving this matrix equation is shown.

In this embodiment, as shown in FIG. 9, the unknown current is divided into a current block (1) and a current block. Block (2), current block (3), and current block (4), and all the interactions between the blocks are put into the current block (4). For matrices related only to block (1), current block (2), and current block (3), the initial value can be approximated by neglecting the interaction between blocks. As a result, the interaction between the current blocks other than the current block (4) can be corrected by the block iteration method (block Jacobian method, block Gauss Seidel method, block SOR method). Furthermore, regarding the matrix related to the current block (4), the direct method is used to consider the interaction between the current block (4) and each of the other current blocks (1), (2), (3). Can be obtained. In other words, since the number of unknown currents is minimal, it can be calculated with a small amount of calculation even if the direct method is used. As a result, even when the blocks are connected by two or more sides, the correct electromagnetic field distribution can be obtained by combining the calculation using the minimum slow direct method and the calculation using the fast block iteration method. Can be sought.

[0039] The procedure is described in detail below.

Equation (9) can be written down as the following equations (10) and (11). This is a simple mathematical variant.

[0040] [Equation 6]

it 0)

The computation cost (used memory, computation time) of the matrix operations is the one that calculates the inverse matrix. The overall calculation cost can be reduced by efficiently calculating the inverse matrix.

(10) In equation (11), there are the following four points ((12) (15)) for calculating the inverse matrix. [0042] [Equation 7]

-1.

½ 12 13 _ι -21 _.24 ^ 4 (1 5〉

, ¾ ¾ ¾ 34 ^ί 4

[0043] Inverse matrix in equations (12) to (15)

[0044] [Equation 8] 11,

twenty one

' twenty three

[0045] is an inverse matrix of the impedance matrix related only to the current block (1), the current block (2), and the current block (3). The current block (1), the current block (2), and the current block ( Since there is no interaction with 3), it is possible to use the block iteration method to calculate Eq. (16). If the block iteration method can be used, the calculation cost can be reduced because the memory used and the amount of calculation (that is, the calculation time) can be reduced compared to the method for obtaining the normal inverse matrix. In addition, in the calculation of the inverse matrix of equation (14) including the term related to the current block (4), the number of sides connecting the blocks is 12, so the large matrix to calculate the inverse matrix is large. The size is 12 x 12, and the calculation cost is lower than the inverse matrix of 147 x 147 when the conventional method of moments is applied.

[0046] Specifically, the inverse matrix of equation (16) is calculated by an iterative method, and from this, equations (12), (13), and (15) are calculated. Further, using the result of equation (12), the inverse matrix of equation (14) is calculated by the direct method. By calculating the current vectors I, I, I, and I using the obtained calculation results and (10) and (11),

1 2 3 4

Find all unknown current values. .

[0047] In step S8, an electromagnetic field at an arbitrary point can be calculated by calculating a green function for the obtained current value in the same manner as in the conventional moment method.

[0048] This method requires less calculation resources such as calculation time and used memory than the conventional moment method. In other words, in the conventional calculation method using only the direct method, when the number of unknown currents is N, the calculation amount is 0 (N ³ ), but in the method according to the present invention, the calculation amount is 0 (N ² ). Become. Therefore, the calculation time can be shortened depending on this. In addition, the memory used is 1Z9 in the case of the present embodiment in which the metal element is divided into three blocks, so that calculation resources can be saved.

[0049] In the first embodiment, the element is divided into two blocks and the unknown current is divided into three blocks. In the second embodiment, the element is divided into three blocks and the unknown current is divided into four blocks. In the example shown in Fig. 8, when the element is divided into N-1 blocks and the unknown current is divided into N blocks, the same calculation can be performed using the following formula.

[0050] [Equation 9]

<1? )

[0051] Embodiment 3. In the third embodiment, the problem of electromagnetic wave scattering by a car is analyzed.

FIG. 10 is a diagram in which the metal structure (vehicle) 20 according to the third embodiment is divided into triangular elements. For these triangular elements, the electromagnetic field distribution was calculated according to the flowchart in Fig. 1 (a). In the third embodiment, the number of block divisions of the element specified in step S2 is three as in the second embodiment.

[0052] In step S3, the current on the shared side shared between the elements is set as an unknown current. In step S4, the number of elements constituting each element block is divided into 5,000 elements or less (it changes according to the memory used, but about 5,000 is appropriate for the current computer calculation speed). The triangular element is divided into blocks so that the number of element sides shared between each element block is minimized. For example, it is divided into a roof part, a bonnet part, and a car body part so that the boundary part of the element block comes to the column part of the vehicle window.

In step S5, the unknown current set in step S3 is divided into four blocks as shown in FIG. Fig. 11 ( _a ) shows the unknown current of the current block (1), showing 542 unknown currents belonging to the roof of the car. Figure 11 (b) shows the unknown current in the current block (2), showing 1394 unknown currents belonging to the hood of the car. Figure 11 (c) shows the unknown current of the current block (3), which shows 1620 unknown currents belonging to the car body. Fig. 11 (d) shows the unknown current of the current block (4), the unknown current flowing in the side connecting the car roof and the hood, the unknown current flowing in the side connecting the car roof and the body, and the car This shows 42 unknown currents consisting of unknown currents flowing on the edge connecting the bonnet and the body.

[0053] In step S6, a block matrix equation is created for each current block divided into blocks. In step S7, this block matrix equation is combined with the block iteration method and the direct method in the same manner as in the second embodiment. After calculating all unknown current values, the Green field was calculated on the obtained current values to calculate the electromagnetic field distribution.

The total of all unknown currents is 3598. Compared to the case where the 3598 X 3598 matrix equation is solved by the direct method, when the solution is divided by the method of the present invention, the calculation time is about 1Z5. The memory could be solved with 1Z4.

FIG. 12 is a block diagram of the electromagnetic field distribution calculating apparatus according to the third embodiment. Car gold When the genus structure element data 1 is input from the element data input means 2 to the electromagnetic field distribution calculation device, processing corresponding to each step in FIG. 1 is executed by a program in the computer. The functional blocks expressed by means 3 to 8 in Fig. 12 exist in the program in the computer.

[0055] In each of the above embodiments, when performing block division of the metal element in step S4, the block division is optimized by an optimization method so that the number of unknown currents flowing between the element blocks is minimized. You may optimize the block division visually by using a CAD tool.

Further, this method can be applied even if the number of unknown currents flowing between the element blocks is not necessarily the minimum. When the number of unknown currents flowing between the element blocks increases, the calculation time is not shortened as compared with the above embodiments, but the memory used for the calculation can be smaller than the conventional direct method.

Claims

The scope of the claims

[1] First step of dividing the surface of the metal structure into a plurality of elements having a small area force. For the plurality of divided elements, a shared edge between the elements is detected, and the perpendicular to the shared edge is detected. 2nd step to set unknown current, 3rd step to divide the multiple elements into N-multiple element blocks, 3rd step to set unknown currents to each element block Each block is divided separately into N—1 current block n that belongs only to each element block, and a current block m that combines unknown currents flowing between the element blocks into a fourth block. Step 5 for creating a block matrix equation by the electric field integral equation moment method for each current block divided into N blocks. Bro The sixth step of calculating unknown current values of all current blocks using the block iteration method for the calculation of the term related only to the current block n, and the direct method for the calculation of the term related to the current block m, and An electromagnetic field distribution calculation method comprising a seventh step of calculating an electromagnetic field distribution around a metal structure based on the unknown current value of each obtained current block.

[2] In the sixth step, the block iteration method is used to calculate the inverse matrix related to N—one current block n, and the direct method is used to calculate the inverse matrix related to current block m. The electromagnetic field distribution calculation method according to claim 1, wherein:

[3] The electromagnetic field distribution calculation method according to claim 1, wherein in the third step, block division is performed so that the number of unknown currents flowing between the element blocks is minimized.

4. The electromagnetic field distribution calculation method according to claim 1, wherein the metal structure is a vehicle, and a boundary portion of the element block is defined in a support portion of the window of the vehicle.

[5] An input means for inputting element data on the surface of a metal structure divided into a plurality of elements having a small area force. For the plurality of divided elements, a shared edge between each element is detected, and the sharing is performed. An unknown current setting means for setting an unknown current perpendicular to the side, an element block dividing means for dividing the plurality of elements into a plurality of N element blocks, and a plurality of the unknown currents set to each element block The current is divided into N—1 current block n that belongs only to each element block and is divided into each current block m, and the current block m that combines the unknown current flowing between each element block. Block dividing means, For each current block divided into N blocks, a block matrix equation constructing means for creating a block matrix equation by the electric field integral equation moment method, and when solving the above block matrix equation, the above N— 1 current block n The block iteration method is used for the calculation of the term related only to the current block, the direct method is used for the calculation of the term related to the current block m, the solution means for calculating the unknown current values of all the current blocks, and each obtained An electromagnetic field distribution calculating apparatus comprising an electromagnetic field distribution calculating means for calculating an electromagnetic field distribution around a metal structure based on an unknown current value of a current block.

The first step of dividing the metal structure surface into a plurality of elements with a small area force. For the divided elements, a shared edge between each element is detected, and an unknown number perpendicular to the shared edge. 2nd step to set current, 3rd step to divide the multiple elements into N-multiple element blocks, 3 separate unknown currents set for each element block A fourth step of dividing the block into N—one current block n that belongs only to each element block and a current block m in which unknown currents flowing between the element blocks are grouped together. For each current block divided into N blocks, the fifth step of creating a block matrix equation by the electric field integral equation moment method, the N-1 current block when solving the block matrix equation The sixth step of calculating unknown current values of all current blocks using the block iteration method for the calculation of the term related only to n and the direct method for the calculation of the term related to the current block m, and An electromagnetic field distribution calculation program that executes a seventh step of calculating an electromagnetic field distribution around the metal structure based on the unknown current value of each current block.