JP2010122089A - Method and apparatus for computing direct current superposition inductance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct current superposition inductance computing method capable of accurately computing the inductance and direct current superposition characteristics of magnetic parts with a small amount of computation in a short computation time without having to produce a trial product. <P>SOLUTION: By using, as the initial magnetization characteristics of a magnetic material, the integration characteristics of a characteristic curve of magnetic permeability-field strength of the magnetic material made of the same material as that of a magnetic member and having a closed magnetic circuit shape or characteristics obtained by performing demagnetization correction on the integration characteristics of a characteristic curve of magnetic permeability-field strength of the magnetic material made of the same material as that of the magnetic member and having an open magnetic circuit shape, inductance L is determined by equation on the basis of magnetic flux density B<SB>I</SB>and field strength H<SB>I</SB>generated by an exciting current I of the magnetic member to a characteristic DC current component; magnetic flux density B<SB>I+dI</SB>and field strength H<SB>I+dI</SB>generated by the sum of the exciting current I and a very small electric current dI; and the volume v of the space enveloping the magnetic member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for calculating an inductance of a magnetic member excited by a current in which an alternating current is superimposed on a direct current, such as a smoothing choke of a switching power supply, and a direct current superimposed inductance calculating apparatus.

  Estimating the DC superimposed inductance using a calculation device is effective for grasping the characteristics of an inductor such as a smooth choke without making a prototype, leading to improvement in development efficiency and shortening of the development period.

  For the calculation of the magnetic field that is the basis for estimating the inductance, the approximation is performed by the difference method or the finite element method based on the Maxwell equation, and the magnetic member that is the object of the inductance calculation is divided into small regions. For example, Patent Document 1 describes a basic equation and an approximation method therefor.

  In Patent Document 1, the following is proposed for the calculation of the DC superimposed inductance. That is, in an inductance calculation apparatus for calculating the inductance of a magnetic member excited by a current obtained by superimposing an alternating current on a direct current, the initial magnetization characteristics of the magnetic material having the same material as the magnetic member and a shape having a minimum demagnetizing factor and First magnetic flux density calculating means for calculating the magnetic flux density of each minute region of the magnetic member with respect to the direct current component based on geometric information of the magnetic member; the magnetic flux density calculated by the first magnetic flux density calculating means and the same material as the magnetic member Incremental permeability determining means for determining the incremental permeability of each minute region based on the incremental permeability of a magnetic material having a shape having a minimum demagnetizing field coefficient; the incremental permeability of each minute region of the magnetic member and the magnetic member Second magnetic flux density and magnetic field strength calculating means for calculating a magnetic flux density and a magnetic field strength with respect to an alternating current component of the magnetic member based on geometric information; and a second magnetic flux density and a magnetic field An inductance computing device DC superposition comprising; degrees calculating means calculating means for calculating the inductance of the magnetic member based on the magnetic flux density and magnetic field strength was calculated.

  According to the inductance calculation method of Patent Document 1, the magnetic flux density (Bdc) with respect to the DC bias current component of the magnetic component calculated from the initial magnetization characteristics of the magnetic material having the same material as the magnetic component and the shape having the smallest demagnetizing factor. The material constant is determined based on the incremental permeability (μ) of the magnetic material, and the inductance (L) of the magnetic component is calculated based on the magnetic flux density (Bac) with respect to the alternating current component of the magnetic component calculated from the material constant. Therefore, it is described that the DC superimposition characteristic of a magnetic part having an arbitrary shape with one magnetic material can be accurately calculated without particularly making a magnetic part prototype, and the trial cost and the trial period are shortened.

  In addition, since a single calculation can be performed in a relatively short time even on a small computer, calculation levels can be set for multiple material characteristics and shapes, and the optimum material for the specified DC superimposition characteristics required for equipment design. The shape can be determined.

Japanese Patent No. 2984108

  However, the inductance calculation method described in Patent Document 1 has a problem in that it requires a large amount of calculation to calculate the inductance, which takes time.

  In Patent Document 1, based on the initial magnetization characteristics and magnetic member geometric information of a magnetic material that has the same material as the magnetic member and has a minimal demagnetizing factor in the calculation process, The process of calculating the magnetic flux density (Bdc) of the minute region, the incremental transmission of the magnetic material having the same material as the magnetic member and the magnetic material having the minimum demagnetizing factor coefficient, and the magnetic flux density (Bdc) calculated by the first magnetic flux density calculating means. A process for determining the incremental magnetic permeability of each minute region based on the magnetic permeability, that is, a calculation means focusing on each minute region of the magnetic member is essential.

  In calculating the inductance of a magnetic member, when performing approximation by a difference method or a finite element method, the magnetic member is generally divided into minute regions. In order to accurately calculate the inductance, the number of divisions is, for example, several hundred to several tens of thousands even in a magnetic member of about several millimeters, and in some cases, several hundreds of thousands. Based on the initial magnetization characteristics of the magnetic material having the same material as the magnetic member and the minimum demagnetizing factor, and the geometric information of the magnetic member for each division number of the magnetic member, The process of calculating the magnetic flux density (Bdc) of each minute region of the magnetic member with respect to the current component, the shape with the same material as the magnetic flux density (Bdc) calculated by the first magnetic flux density calculating means and the minimum demagnetizing field coefficient The process of determining the incremental magnetic permeability of each minute region based on the incremental magnetic permeability of the magnetic material that has been processed means that the calculation amount is large as it is and the calculation time is long.

  Accordingly, an object of the present invention is to provide a DC superimposed inductance calculating method and a DC superimposed inductance calculating apparatus capable of calculating the inductance and DC superimposed characteristics of a magnetic component without producing a prototype, and with a small amount of calculation and calculation time. It is in.

In order to solve the above problems, the present inventors have made the following inventions as a result of various studies. That is, a method for calculating the inductance of a magnetic member excited by a current obtained by superimposing an alternating current on a direct current, which is based on the initial magnetization characteristics of a magnetic material having the same material as that of the magnetic member and having a closed magnetic circuit shape. A second magnetic flux density B _{I + dI} generated by the first magnetic flux density B _I generated by the excitation current I of the member, the first magnetic field strength H _I , and the sum of the excitation current I and the minute current dI superimposed (I + dI), DC superposition that can calculate the inductance of the magnetic component and the DC superposition characteristics with a small amount of calculation and calculation time by calculating the inductance L from the second magnetic field strength H _{I + dI} and the volume v of the space containing the magnetic member according to _Equation 1. It has been found that an inductance calculation method can be provided.

  In addition, as an initial magnetization characteristic for calculating the magnetic flux density and the magnetic field strength, an integral characteristic obtained by integrating a permeability-magnetic field strength characteristic curve of a magnetic material having a closed magnetic circuit shape made of the same material as the magnetic member measured in advance is used. It has been found that the calculation of the DC superimposed inductance can be performed with high accuracy by using it.

  Furthermore, when the magnetic member has an open magnetic circuit structure having substantially a demagnetizing field coefficient, the magnetic material having the same magnetic material as the magnetic member and having an open magnetic circuit shape as initial magnetization characteristics for calculating magnetic flux density and magnetic field strength DC integral inductance can be calculated with high accuracy by using the integral characteristic obtained by demagnetizing the magnetic material using the demagnetizing field coefficient of the integral characteristic obtained by integrating the magnetic permeability-magnetic field strength characteristic curve of the magnetic material. I found.

  The present invention is also a DC superimposed inductance calculation apparatus comprising means for calculating the inductance of a magnetic member excited by a current obtained by superimposing an AC current on a DC current by any one of the three DC superimposed inductance calculation methods described above. is there.

  According to the present invention, it is possible to provide a DC superimposed inductance calculating method and a DC superimposed inductance calculating apparatus capable of calculating the inductance and DC superimposed characteristics of a magnetic component with a small amount of calculation and calculation time.

  The best mode for carrying out the present invention will be described below with reference to the drawings. When the target is a magnetic member having a closed magnetic circuit structure, the calculation of the DC superimposed inductance can be performed with high accuracy by the following. In addition, unless otherwise indicated below, it is an SI unit system.

  FIG. 2 is a diagram showing an overview of a wound closed magnetic circuit core, which is a magnetic member composed of a magnetic material 2 and a toroidal closed magnetic circuit core made of a magnetic wire 2 and a conducting wire 1 wound in a coil shape. is there. A magnetic permeability-magnetic field strength curve (hereinafter referred to as a μ-H curve) of the magnetic member is measured in advance. For the measurement, for example, a commercially available measuring instrument such as LCR meter can be used. FIG. 3 is a diagram showing the relationship of magnetic field strength H-permeability μ of the wound closed magnetic path core, and a μ-H curve as shown in FIG. 3 is obtained for the magnetic member of FIG.

  FIG. 4 is a diagram showing a curve obtained by integrating the magnetic field strength H-permeability μ curve of the wound closed magnetic path core. The obtained μ-H curve is numerically approximated with an appropriate function, and the function is numerically integrated to obtain a μ-H integration curve (∫μdH curve) as shown in FIG. For example, a trapezoidal approximation method may be used to derive the μ-H integral curve. The μ-H integral curve has the same dimension as the magnetic flux density B according to its definition.

Using the obtained μ-H integral curve and a predetermined DC current value I, the Maxwell equation detailed in Patent Document 1 is solved to obtain a magnetic flux density B _I corresponding to the DC current value I and a magnetic field strength H. _I can be obtained.

Similarly, by using the μ-H integral curve and the current value I + dI obtained by adding the minute current value dI superimposed on the predetermined DC current value I, by solving the Maxwell equation, the magnetic flux density corresponding to the DC current value I + dI B _{I + dI} and magnetic field strength H _{I + dI} are obtained.

FIG. 5 corresponds to the predetermined DC current value I, the magnetic flux density B _I corresponding to the DC current value I, the magnetic field intensity H _I , and the current values I + dI and I + dI obtained by adding the minute current value dI to the predetermined DC current value I. It is a figure which shows the relationship between magnetic flux density B _{I + dI} and magnetic field intensity H _{I + dI} . Since the slope of the line segment composed of B _I , H _I , B _{I + dI} , H _{I + dI} is nothing but the magnetic permeability of the magnetic member, the difference from B _I , B _{I + dI} is dB, the difference between H _I , H _{I + dI} is dH, Formula (1) and Formula (2)
dB = B _{I + dI} −B _I (1)
_{dH = H I + dI -H I} (2)
Then, the minute energy dE accumulated in an arbitrary minute space where the magnetic member exists is expressed by Equation 2 with respect to the inductance L, where v is the volume of the analysis space, and the inductance is calculated by Equation 3 from here. Can do.

なお、数３は、ｄＢおよびｄＨに対する式（１）および式（２）を参照すれば、数１と同じ内容のものである。

Note that Equation 3 has the same contents as Equation 1 with reference to Equation (1) and Equation (2) for dB and dH.

  The calculation procedure of the DC superimposed inductance in the case of a magnetic member having an open magnetic circuit structure will be described in more detail.

  FIG. 6 is a diagram showing an overview of a magnetic material composed of a wound open magnetic path core. As shown in FIG. 6, the magnetic member 4 is composed of a toroidal open magnetic path core composed of a magnetic material 4, a conductive wire 3 wound around the magnetic material 4 in a coil shape, and an air gap 5 provided in the magnetic material 4. The H curve is measured in advance. FIG. 7 is a diagram showing the relationship between the magnetic field strength H of the wound open magnetic path core and the magnetic permeability μ.

  FIG. 8 is a diagram showing a curve obtained by integrating a magnetic field strength H-permeability μ curve of a wound open magnetic path core, and a magnetic field strength H-permeability μ integration curve corrected for a demagnetizing field. The obtained μ-H curve is numerically approximated with an appropriate function, and the function is numerically integrated to obtain a μ-H integration curve (as shown in the integral curve 6 of magnetic field strength H-permeability μ in FIG. ∫μdH curve) is obtained. Note that the trapezoidal approximation method may be used to derive the μ-H integral curve. The μ-H integral curve has the same dimension as the magnetic flux density B according to its definition.

Inside diameter l _Innner of the magnetic member made of a toroidal-shaped closed magnetic path core, external l _outer, from the height h, obtaining the effective area A by the following equation (3).
A _e = (l _inner −l _outer ) / 2 × h (3)
Similarly determine the effective magnetic path length L _e by the following equation (4).
L _e = (l _inner + l _outer ) / 2 × π (4)

Using the μ-H integral curve of the toroidal open magnetic circuit core, the initial inductance is obtained from Equation 5 by solving the Maxwell equation from the stored energy E ₀ (shown in Equation 4) of the current I ₀ with respect to the initial magnetization characteristics. determine the L _0.

ここで、Ｂ₀およびＨ₀は、初磁化特性に関わる磁束密度と磁界を表す。

Here, B ₀ and H ₀ represent the magnetic flux density and the magnetic field related to the initial magnetization characteristics.

From the obtained A _e , L _e , L ₀ , and the number n of turns of the conducting wire 3 that is the winding of the open magnetic circuit core, the effective permeability μ _e is obtained by the following equation (5).
μ _e = L ₀ × L _e / A _e / n ² / (4π × 10 ⁻⁷ ) (5)

The demagnetizing factor N is obtained from Equation (6) showing the relationship between the intrinsic permeability μ _m of the magnetic material 4 of the open magnetic path core and the effective permeability μ _e described above.
_{1 / μ m = 1 / μ} e - N (6)
Ｎ N = 1 / μ _e −1 / μ _m (7)

Using the demagnetizing factor N obtained in this way, an integral curve 6 (∫μdH curve) of magnetic field strength H−permeability μ shown in FIG. Similarly to the demagnetizing field correction of the H curve, the demagnetizing field correction is performed on an arbitrary magnetic field strength H (Oe) and magnetic flux density B (G), and the demagnetizing field against the effective magnetic field strength Heff (Oe) as shown in FIG. An integral curve 7 (∫μdHeff (G)) of corrected magnetic field strength H−permeability μ is obtained by Equation 6.
Heff = H−B × N (8)

尚、反磁界係数Ｎを種々変化させて検討を行った結果、∫μｄＨｅｆｆ−Ｈｅｆｆ曲線は反磁界係数Ｎに依存せず、全て同一の挙動を示すことが分かった。

As a result of various changes in the demagnetizing factor N, it was found that the ∫μdHeff-Heff curve does not depend on the demagnetizing factor N and all exhibits the same behavior.

By using the obtained demagnetizing field correction μ-H integral curve and a predetermined direct current value I and solving the Maxwell equation, the magnetic flux density B _I and the magnetic field strength H _I corresponding to the direct current value I can be obtained.

Similarly, the magnetic flux density B corresponding to the DC current value I + dI is obtained by solving the Maxwell equation using the demagnetizing field correction μ-H integral curve, the current value I + dI obtained by adding the minute current value dI to the predetermined DC current value I. _{I + dI} and magnetic field strength H _{I + dI} are obtained.

The relationship among B _I , H _I , B _{I + dI} , and H _{I + dI} is basically as shown in FIG. Therefore, as described above, the energy accumulated in an arbitrary space where the magnetic member exists from the difference dH between B _I , B _{I + dI} , H _I , H _{I + dI} is v and the minute current dI. As described above, the inductance is obtained by the above-described equation 2, and the inductance can be calculated by the aforementioned equation 3, that is, the equation 1.

  FIG. 1 is a diagram showing an implementation flowchart of the present invention. Hereinafter, specific embodiments of the present invention will be described in detail with reference to the flowchart shown in FIG.

Example 1
Analysis of a closed magnetic circuit toroidal magnetic member having an outer diameter of 16 mm, an inner diameter of 10 mm, a height of 6 mm, and a coil turn number of 15 was performed by the following procedure.

  First, a permeability-magnetic field strength curve (hereinafter referred to as a μ-H curve) of a toroidal closed magnetic path core as shown in FIG. 2 was measured (step 101 in FIG. 1). Agilent 4284A LCR meter was used for the measurement. FIG. 9 is a diagram showing the relationship between the magnetic field strength H and the magnetic permeability μ of the wound closed magnetic circuit toroidal magnetic member according to the embodiment of the present invention.

  FIG. 10 is a diagram showing a curve obtained by integrating a magnetic field strength H-permeability μ curve of a wound closed magnetic circuit toroidal magnetic member according to an embodiment of the present invention. The μ-H integral curve (∫μdH curve) shown in FIG. 10 was obtained by numerical integration of the μ-H curve in FIG. 9 (step 102 in FIG. 1). At this time, the curve of FIG. 9 is approximated by an appropriate function.

  FIG. 11 is a diagram illustrating a configuration of a DC superimposed inductance calculation apparatus according to an embodiment of the present invention. The numerical value of the μ-H integral curve in FIG. 10 and the predetermined DC current value I were input to the DC superimposed inductance calculating apparatus having the configuration shown in FIG. 11 (step 104 in FIG. 1). Note that the DC superimposed inductance calculation device may use a commercially available personal computer or the like as long as it has a similar function. When the magnetic member has no demagnetizing field, demagnetizing field correction is unnecessary (corresponding to step 103 in FIG. 1).

Subsequently, geometric information (inner diameter, outer diameter, height) of the magnetic material 2 was input (step 105 in FIG. 1). Based on these numerical values, the Maxwell equation was solved by the finite element method with a DC superimposed inductance calculation device to obtain the magnetic flux density B _I and the magnetic field strength H _I corresponding to the DC current value I (step 106 in FIG. 1). ).

  A finite element method was used for the calculation, and the number of core divisions was 100,000. In the magnetic field calculation, non-linear iterative calculation using the Newton-Raphson method, which is general as a non-linear magnetic field analysis by the finite element method, was performed on a minute region based on geometric information. The same applies to all examples and comparative examples. In all Examples and Comparative Examples, convergence was achieved by about 10 to 13 iterations.

Similarly, the magnetic flux corresponding to the DC current value I + dI is solved by solving the Maxwell equation using the μ-H integral curve and the current value I + dI obtained by adding the minute current value dI superimposed on the predetermined DC current value I. Density B _{I + dI} and magnetic field strength H _{I + dI} were obtained. The finite element method was used for the calculation, and the number of core divisions was similarly set to 100,000 (step 107 in FIG. 1).

From the relationship of B _I , H _I , B _{I + dI} , and H _{I + dI} obtained in this way, the inductance L was calculated according to Equation (1) to Equation 3 (step 108 in FIG. 1). Note that the volume of the analysis region is a cube with the magnetic member as the center and three times the maximum length of the magnetic member as one side. The same applies to all the following examples. Hereinafter, calculation of the inductance L corresponding to each current value I was repeated using the predetermined current value I as a parameter (step 109 in FIG. 1), and a DC superimposed inductance LI characteristic was obtained.

(Example 2)
FIG. 12 is a diagram showing an overview of a product-shaped magnetic member according to an embodiment of the present invention. As shown in FIG. 12, the magnetic core 8 made of a magnetic material having a length of 3 mm × width 3 mm × height 1.2 mm, bobbin shape and inherent permeability μm≈500, and magnetic metal powder are dispersed, μ≈10 Analysis of an open magnetic path magnetic member comprising a mold resin 9 and a conductive wire 10 wound in a coil shape on the middle leg of the magnetic core 8 was performed according to the following procedure in accordance with the flowchart of FIG.

  First, an open magnetic circuit toroidal core of the same material as the magnetic core of the magnetic member shown in FIG. 12, having an outer diameter of 16 mm, an inner diameter of 10 mm, a height of 6 mm, a coil turn number of 15 and a gap of 1.2 mm in width. The permeability-magnetic field strength curve (hereinafter referred to as μ-H curve) was measured (step 101 in FIG. 1). Agilent 4284A LCR meter was used for the measurement. FIG. 13 is a diagram showing the relationship between the magnetic field strength H of the wound open magnetic path core and the magnetic permeability μ in the embodiment of the present invention.

  FIG. 14 relates to an embodiment of the present invention, and shows a curve obtained by integrating a magnetic field strength H-permeability μ curve of a wound open magnetic path core, and a magnetic field strength H-permeability μ integration curve corrected for a demagnetizing field. FIG. The μ-H curve (に μdH curve) shown in the integral curve 11 of FIG. 14 is obtained by approximating the μ-H curve of FIG. 13 by a function and numerically integrating the function. (Step 102 in FIG. 1).

  Since the closed magnetic path magnetic member of the present embodiment has a demagnetizing field, demagnetizing field correction was performed on the integral curve 11 of the magnetic field strength H-permeability μ in FIG. 14 according to the following procedure (step 103 in FIG. 1). ).

Inside diameter _l innner = 10mm of toroidal closed magnetic path core, external l _outer = 16 mm, the height h = 6 mm, equation (3), determine the effective area A _e and the effective magnetic path length L _e by equation (4) It was.
A _e = (l _inner −l _outer ) /2×h=18.0 mm ²
L _e = (l _inner + l _outer ) /2×π=40.8 mm

Next, with respect to the toroidal open magnetic circuit core, the initial inductance L ₀ was obtained by Equation 5.

Subsequently, from the obtained A _e , L _e , L ₀ , and the coil turn number n = 15 of the open magnetic path core, the effective magnetic permeability μ _e was obtained by the equation (5).

From the unique permeability mu _m and the effective permeability mu _e of the magnetic material to obtain the demagnetizing factor N by the equation (7).

  Using the obtained demagnetizing factor N, a general BH curve demagnetizing field correction using Equation (8) and Equation 6 for the μ-H integral curve 11 (∫μdH (G)) of FIG. Similarly, a demagnetizing field correction is performed on an arbitrary magnetic field strength H (Oe) and magnetic flux density B (G), and the demagnetizing field correction H-permeability μ integral field 12 shown in FIG. (Oe) and magnetic flux density ∫μdHeff (G) were obtained.

  The numerical value of the integral curve 12 of the magnetic field strength H-permeability μ corrected for the demagnetizing field in FIG. 14 and the predetermined DC current value I are input to the DC superimposed inductance calculating apparatus having the configuration shown in FIG. 11 (104 in FIG. 1). Process). Furthermore, the geometric information of the magnetic member was input (step 105 in FIG. 1).

The Maxwell equation was solved by a finite element method using a calculation device, and magnetic flux density B _I and magnetic field strength H _I corresponding to DC current value _I were obtained (step 106 in FIG. 1). A finite element method was used for the calculation, and the number of core divisions was 200,000.

Similarly, by using the μ-H integral curve, the current value I + dI obtained by adding the superposed minute current value dI to the predetermined DC current value I, by solving the Maxwell equation, the magnetic flux density B _{I + dI} corresponding to the DC current value _{I + dI} , Magnetic field strength H _{I + dI} was obtained (step 107 in FIG. 1). A finite element method was used for the calculation, and the number of core divisions was 200,000.

From the relationship of B _I , H _I , B _{I + dI} , H _{I + dI} , the inductance L was calculated according to Equation (1), Equation (2), Equation 2, and Equation 3 (step 108 in FIG. 1).

  Hereinafter, the above calculation procedure was repeated using a predetermined current value as a parameter (step 109 in FIG. 1), and a DC superimposed inductance LI characteristic was obtained.

(Comparative Example 1)
Analysis of a closed magnetic circuit toroidal magnetic member having an outer diameter of 16 mm, an inner diameter of 10 mm, a height of 6 mm, and a coil turn number of 15 was performed by the following conventional procedure different from the method of the present invention.

  FIG. 15 is a diagram showing a relationship between magnetic field strength H and magnetic flux density B of a wound closed magnetic circuit toroidal magnetic member according to a comparative example of the present invention. A magnetic flux density-magnetic field strength curve (hereinafter referred to as a BH curve) of the above magnetic member was measured to obtain a BH curve shown in FIG. An Agilent 4194A impedance analyzer was used for the measurement.

  Subsequently, a magnetic permeability-magnetic field strength curve (hereinafter referred to as a μ-H curve) of the magnetic member was measured. Agilent 4284A LCR meter was used for the measurement. A μ-H curve similar to that shown in FIG. 9 was obtained.

Magnetic field calculation was performed based on the geometric information of the magnetic member, the BH curve, and the DC superimposed component value of a predetermined DC superimposed current. The calculation was performed by solving the Maxwell equation and the finite element method was used. The core division number in the finite element method and 100,000, were determined permeability mu _i of each minute divided areas.

The incremental magnetic permeability μ _i of each minute region was associated with each minute region, and the calculation was performed using the same magnetic field calculation method from the geometric information and the alternating current component value Iac of the direct current superimposed current.

  The inductance L was obtained from Equation 7 from the magnetic flux density Bac corresponding to the AC current component and the magnetic field strength Hac.

  The above calculation was repeated according to a predetermined number of superimposed current components, and a DC superimposed inductance LI characteristic was obtained.

(Comparative Example 2)
As shown in FIG. 12, the open magnetic circuit has a mold portion of 3 mm in length, 3 mm in width, and 1.2 mm in height, in which the magnetic permeability of the core material is dispersed with a magnetic permeability of μm≈500, μ≈10. The magnetic member was analyzed by the following procedure similar to that of Comparative Example 1.

First, measurement of magnetic flux density-magnetic field strength curve (BH curve) and permeability-magnetic field strength of a closed magnetic circuit toroidal core of the same material as the core material with an outer diameter of 16 mm, an inner diameter of 10 mm, a height of 6 mm, and a coil turn number of 15. The curve (μ-H curve) was measured, and the magnetic field was calculated by the finite element method based on the geometric information of the title magnetic member, the BH curve, and the DC superimposed component value of a predetermined DC superimposed current. The number of core divisions in the finite element method was 200,000, and the magnetic permeability μ _i of each divided micro area was determined.

The incremental magnetic permeability μ _i of each minute region was associated with each minute region, and the DC superimposed inductance L-I characteristic was obtained in the same manner as in Comparative Example 1.

  FIG. 16 relates to an example of the present invention, and shows calculation results and actual measurement results in Example 1 and Comparative Example 1 of a closed magnetic circuit toroidal magnetic member having an outer diameter of 16 mm, an inner diameter of 10 mm, a height of 6 mm, and a coil turn number of 15. FIG. As can be seen from FIG. 16, it can be seen that the calculation results in Example 1 and Comparative Example 1 and the actual measurement values are in good agreement.

  FIG. 17 relates to an example of the present invention. Example 2 of an open magnetic path magnetic member, which is 3 mm long × 3 mm wide × 1.2 mm high and has a mold part in which magnetic metal powder is dispersed, and Comparative Example 2 It is a figure which shows the direct current superimposition characteristic calculation result of this, and an actual measurement result. As can be seen from FIG. 17, it can be seen that the calculation results in Example 2 and Comparative Example 2 and the actual measurement values are in good agreement.

  In Example 1, Example 2, Comparative Example 1, and Comparison 2, judging from the calculation results, there is no great difference and shows good agreement with the actual measurement values. That is, it can be seen that the method according to the present invention has practicality.

  Table 1 shows the time required to calculate all the inductances for a predetermined DC superimposed current in Example 1, Example 2, Comparative Example 1, and Comparative Example 2, and Comparative Example 1 is compared with Example 1. Comparative Example 2 is shown in comparison with Example 2.

  As can be seen from Table 1, Example 1 of the present invention has a calculation time of about 1/6 compared to Comparative Example 1, and Example 2 has a calculation time of about 1/10 compared to Comparative Example 2. Greatly improved. The actual calculation time greatly depends on the CPU capability shown in FIG. 11, but the time required to calculate all of the predetermined DC superimposed current is approximately 1 hour in the first embodiment. In Example 2, it was about 2 hours.

  In Examples 1 and 2 of the present invention, only the μ-H curve is required as material property information, whereas in Comparative Examples 1 and 2, two types of BH curve and μ-H curve are required. And That is, it can be said that the measurement time required for preparation for calculation is short in the method according to the present invention.

The figure which shows the implementation flowchart of this invention. The figure which shows the general view of the wound closed magnetic circuit core. The figure which shows the relationship of the magnetic field intensity H-magnetic permeability (micro | micron | mu) of the wound closed magnetic path core. The figure which shows the curve which integrated the magnetic field strength H-permeability (micro | micron | mu) curve of the wound closed magnetic circuit core. A predetermined DC current value I, a magnetic flux density B _I corresponding to the DC current value I, a magnetic field intensity H _I , a current value I + dI obtained by adding a minute current value dI to the predetermined DC current value I, and a magnetic flux density B _{I + dI} corresponding to _{I + dI} The figure which shows the relationship of magnetic field intensity HI _{+ dI} . The figure which shows the general view of the magnetic material which consists of a wound open magnetic path core. The figure which shows the relationship of the magnetic field intensity H-permeability (micro | micron | mu) of the open magnetic path core wound. The figure which shows the curve which integrated the magnetic field strength H-permeability (micro | micron | mu) curve of the wound open magnetic path core, and the magnetic field strength H-permeability (micro | micron | mu) integral curve which corrected the demagnetizing field. The figure which concerns on the Example of this invention and shows the relationship of the magnetic field strength H-magnetic permeability (micro | micron | mu) of the wound closed magnetic circuit toroidal magnetic member. The figure which shows the curve which concerns on the Example of this invention and integrated the magnetic field strength H-permeability (micro | micron | mu) curve of the wound closed magnetic circuit toroidal magnetic member. The figure which concerns on the Example of this invention, and shows the structure of a DC superimposed inductance calculation apparatus. The figure which concerns on the Example of this invention and shows the general view of the magnetic member of a product shape. The figure which concerns on the Example of this invention, and shows the relationship of the magnetic field intensity H-permeability (micro | micron | mu) of the wound open magnetic path core. The figure which shows the curve which integrated the magnetic field intensity H-permeability (micro | micron | mu) curve of the wound open magnetic path core in connection with the Example of this invention, and the magnetic field intensity H-permeability (micro | micron | mu) integral curve which corrected the demagnetizing field. The figure which concerns on the comparative example of this invention, and shows the relationship of the magnetic field intensity H-magnetic flux density B of the wound closed magnetic circuit toroidal magnetic member. The figure which shows the calculation result in Example 1 and the comparative example 1 of a closed magnetic circuit toroidal magnetic member of the outer diameter 16mm, inner diameter 10mm, height 6mm, and the number of coil turns 15 in connection with the Example of this invention. In connection with the examples of the present invention, the DC superimposition characteristics of Example 2 and Comparative Example 2 of the open magnetic path magnetic member having a mold portion in which the length is 3 mm × width 3 mm × height 1.2 mm and the magnetic metal powder is dispersed. The figure which shows a calculation result and an actual measurement result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductor 2 Magnetic material 3 Conductor 4 Magnetic material 5 Air gap 6 Integral curve 7 of magnetic field strength H-permeability μ Demagnetized magnetic field strength H-integral curve 8 of magnetic permeability 8 Magnetic core 9 Mold resin 10 Conductor (coil, Ring)
11 Integral curve of magnetic field strength H-permeability μ 12 Integral curve of magnetic field strength H-permeability μ corrected for demagnetizing field

Claims (4)

An inductance calculation method for a magnetic member excited by a current obtained by superimposing an alternating current on a direct current,
Based on the initial magnetization characteristics of a magnetic material made of the same material as the magnetic member and having a closed magnetic circuit shape, the first magnetic flux density BI, the first magnetic field strength HI, and the like generated by the exciting current I of the magnetic member with respect to the direct current component, and The inductance L is calculated from the second magnetic flux density B _{I + dI} generated by the sum (I + dI) of the excitation current I and the minute current dI superimposed, the second magnetic field strength H _{I + dI} , and the volume v of the space containing the magnetic member. A DC superimposed inductance calculation method characterized in that the DC superimposed inductance calculation is performed by Equation (1).

  2. The DC superimposed inductance calculation method according to claim 1, wherein an integral characteristic obtained by integrating a permeability-magnetic field strength characteristic curve of the magnetic material measured in advance is used as the initial magnetization characteristic.   When the magnetic member has an open magnetic circuit structure having a substantially demagnetizing factor, as the initial magnetization characteristic, an integral characteristic obtained by integrating a magnetic permeability-magnetic field strength characteristic curve of the magnetic material measured in advance. 2. The DC superimposed inductance calculation method according to claim 1, wherein an integral characteristic obtained by performing demagnetizing field correction using a demagnetizing field coefficient of the magnetic material is used.   A means for calculating an inductance of a magnetic member excited by a current obtained by superimposing an alternating current on a direct current by the direct current superimposed inductance calculating method according to any one of claims 1 to 3. Superimposed inductance calculation device.

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