A calculation method for the technological coefficient of a transformer core

Abstract

The present invention discloses a calculation method for the technological coefficient of a transformer core, which relates to the technical field of transformer design. The method includes: calculating the core structure coefficient, the core material coefficient, the core surface voltage coefficient, and the core anomaly coefficient respectively, and combining them into the theoretical technological coefficient of the standard core model of the transformer, wherein the core anomaly coefficient is related to the transformer usage environment and the inherent loss of the core; correcting the calculated theoretical technological coefficient according to the technological coefficient error threshold given under the model to which the standard core model belongs. This method constructs a standardized process for calculation with the defined coefficients of the core as the judgment criteria, enhancing the stability of core design.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer design, and in particular to a method for calculating the technological coefficient of a transformer core. Background Art

[0002] At present, for the iron loss calculation of transformer cores, although each manufacturer applies the set of calculation formulas of (unit loss * core weight * technological coefficient), the actual theoretical iron losses given are different. The reason is that each manufacturer determines the technological coefficient in a different way.

[0003] The technological coefficient of a transformer, commonly known as the "empirical coefficient", is a coefficient initially given based on the accumulation of transformer design. Even if cores are designed and manufactured by each manufacturer using the same parameters, the technological coefficients given by each manufacturer are often different. Therefore, it is necessary to formulate a standardized process for the calculation method of the technological coefficient. Summary of the Invention

[0004] In view of the above problems and technical requirements, the inventor of the present invention proposes a method for calculating the technological coefficient of a transformer core to solve the problem of chaotic calculation logic of the technological coefficient of the transformer core at the present stage. The technical solution of the present invention is as follows:

[0005] A method for calculating the technological coefficient of a transformer core includes the following steps:

[0006] Calculate the core structure coefficient, core material coefficient, core surface voltage coefficient, and core anomaly coefficient respectively, and combine them into the theoretical technological coefficient of the standard core model of the transformer, where the core anomaly coefficient is related to the transformer usage environment and the inherent loss of the core;

[0007] According to the technological coefficient error threshold given under the model to which the standard core model belongs, correct the calculated theoretical technological coefficient.

[0008] A further technical solution thereof is that the method for calculating the core structure coefficient includes:

[0009] Define that the core structure coefficient includes an aperture additional coefficient and a joint additional coefficient;

[0010] According to the relationship one between the aperture additional coefficient and the corresponding core structure parameters a, b, and according to the relationship two between the joint additional coefficient and the corresponding core structure parameters c, d, calculate the aperture additional coefficient α and the joint additional coefficient β respectively;

[0011] According to k a =α*β*γ, combine the aperture additional coefficient α and the joint additional coefficient β to obtain the core structure coefficient k a ;

[0012] Among them, a is the width of the iron core steel sheet, b is the aperture of the iron core, c is the seam step of the iron core steel sheets, d is the number of seams between the iron core steel sheets, and γ is the inherent deviation factor of the iron core structure.

[0013] A further technical solution is that the input of Relationship One is b / a and the output is α; the input of Relationship Two is c*d and the output is β.

[0014] A further technical solution is that the method for calculating the iron core material coefficient includes:

[0015] Define that the iron core material coefficient includes a lamination additional coefficient, a stacking additional coefficient, and a shearing additional coefficient;

[0016] According to Relationship Three between the lamination additional coefficient and the corresponding iron core material parameters e and f, and according to Relationship Four between the stacking additional coefficient and the corresponding iron core material parameters ρ, ρ 0 and according to Relationship Five between the shearing additional coefficient and the corresponding iron core material parameter g, calculate the lamination additional coefficient H, the stacking additional coefficient H 1 and the shearing additional coefficient F respectively;

[0017] Based on k b =H*H 1 *F to combine the lamination additional coefficient H, the stacking additional coefficient H 1 and the shearing additional coefficient F to obtain the iron core material coefficient k b ;

[0018] Among them, e is the thickness of the iron core steel sheet, f is the film thickness of the iron core steel sheet, ρ is the standard density of the iron core steel sheet, ρ 0 is the film-containing density of the iron core steel sheet, g is the shearing slice width of the iron core steel sheet, and k is a fixed proportional coefficient.

[0019] A further technical solution is that the input of Relationship Three is e and f, and the output is H=(e -2 *f) / e; the input of Relationship Four is ρ and ρ 0 , and the output is H 1 =ρ 0 / ρ; the input of Relationship Five is g, and the output is F = k*g.

[0020] A further technical solution is that the method for calculating the iron core surface pressure coefficient includes:

[0021] According to Relationship Six between the iron core surface pressure coefficient and the corresponding external action parameter p, calculate the surface pressure additional coefficient k c ;

[0022] Among them, p is the surface pressure corresponding to the torque acting on the iron core steel sheet.

[0023] A further technical solution thereof is that the input of relationship six is p and the output is k c .

[0024] A further technical solution thereof is that the method for calculating the abnormal coefficient of the iron core includes:

[0025] Define that the abnormal coefficient of the iron core includes an environmental coefficient and an inherent iron loss coefficient of the iron core;

[0026] According to relationship seven between the environmental coefficient and the corresponding iron core environmental parameter t, and according to the relationship between the inherent iron loss coefficient of the iron core and the corresponding iron loss coefficient l of the iron core t between them, the environmental coefficient E and the inherent iron loss coefficient L of the iron core are calculated respectively;

[0027] Based on k d = E * L, the environmental coefficient E and the inherent iron loss coefficient L of the iron core are combined to obtain the abnormal coefficient k of the iron core d ;

[0028] wherein, t is the temperature and humidity of the environment where the iron core is located, and l t is the unit iron loss during the assembly of the iron core calculated at the current temperature and humidity of the iron core.

[0029] A further technical solution thereof is that the input of relationship seven is t and the output is E; the input of relationship eight is l t , and the output is L.

[0030] A further technical solution thereof is that the formula for combining the calculated iron core structure coefficient, iron core material coefficient, iron core surface pressure coefficient and iron core abnormal coefficient into the theoretical process coefficient of the standard iron core model is:

[0031]

[0032] wherein, A is the theoretical process coefficient of the standard iron core model, k a is the calculated iron core structure coefficient, k b is the calculated iron core material coefficient, k c is the calculated surface pressure additional coefficient, k d is the calculated abnormal coefficient of the iron core.

[0033] The beneficial technical effects of the present invention are:

[0034] Based on obtaining the standard iron core model of the transformer, this method defines its initial process coefficient to include the iron core structure coefficient, iron core material coefficient, iron core surface pressure coefficient, and iron core anomaly coefficient. Calculate these four types of coefficients respectively to achieve the accurate calculation of the iron core process coefficient; further define the additional coefficient terms included in each coefficient of the transformer iron core according to relevant attributes, determine the additional coefficient values corresponding to the given design parameters based on the relationship between each additional coefficient and the corresponding parameters, and then obtain each coefficient of the iron core through combination; finally, combine each coefficient of the iron core into the theoretical process coefficient of the standard iron core model, and correct it based on the given process coefficient error threshold under the model of the standard iron core model, and construct a standardized process with the defined coefficients of each iron core as the judgment criteria for the calculation logic to enhance the stability of the iron core design, thereby providing a basis for the theoretical calculation of the iron loss performance of the transformer iron core. Description of the Drawings

[0035] Figure 1 is the flowchart of the calculation method for the process coefficient of the transformer iron core provided by this application.

[0036] Figure 2 is the assembly schematic diagram of the standard iron core model provided by this application.

[0037] Figure 3 is the curve graph of the aperture additional coefficient provided by this application.

[0038] Figure 4 is the curve graph of the joint additional coefficient provided by this application.

[0039] Figure 5 is the curve graph of the lamination stacking additional coefficient provided by this application.

[0040] Figure 6 is the curve graph of the shear additional coefficient provided by this application.

[0041] Figure 7 is the curve graph of the torque and surface pressure additional coefficient provided by this application.

[0042] Figure 8 is the curve graph of the anomaly additional coefficient provided by this application.

[0043] Reference Signs: Ⅰ - Lamination Additional Coefficient Curve, Ⅱ - Stacking Additional Coefficient Curve, 1 - Upper Clamping Component Assembly, 2 - Lower Clamping Component Assembly, 3 - Standard Iron Core Model, 4 - Spring Component Assembly, 5 - Foot Pad Component Assembly. Detailed Embodiment

[0044] The following further describes the specific embodiments of the present invention in conjunction with the drawings.

[0045] As Figure 1As shown in the figure, an embodiment of the present application provides a method for calculating the process coefficient of a transformer core, where the process coefficient of the core is related to the core structure, core material, core surface pressure, transformer usage environment, and inherent core loss. To facilitate further determination of the process coefficient of the core, the influence caused by the core structure is defined as the core structure coefficient, the influence caused by the core material is defined as the core material coefficient, the influence caused by the core surface pressure is defined as the core surface pressure coefficient, and there is a certain correlation between the transformer usage environment and the inherent core loss. Therefore, the influence caused by the transformer usage environment and the inherent core loss is jointly defined as the core anomaly coefficient.

[0046] The calculation of each coefficient is inseparable from the designed standard core model. The standard core model made according to the mainstream transformer design concept is referenced Figure 2 As shown in the figure, since the process coefficient of the model preferably has no influence on the core loss, the initial process coefficient of the model set in this embodiment under laboratory conditions is 1. This model can be changed to different silicon steel sheet types according to different core designs, with the rest of the structure remaining unchanged. Optionally, if other models consume more than this model, then the corresponding process coefficient will be a little larger, for example, set to 1.1; the process coefficient of this model can also be set to 1.1 according to actual design requirements. Correspondingly, the process coefficients of other models may be set to 1.21.

[0047] The following steps introduce in detail the calculation methods of each coefficient, specifically including the following steps:

[0048] Step 1: Calculate the core structure coefficient of the standard core model of the transformer, specifically including:

[0049] Step 1.1: Define the core structure coefficient k a It includes the aperture additional coefficient α and the joint additional coefficient β.

[0050] Step 1.2: According to the relationship one between the aperture additional coefficient α and the corresponding core structure parameters a, b, and according to the relationship two between the joint additional coefficient β and the corresponding core structure parameters c, d, calculate the corresponding aperture additional coefficient α and joint additional coefficient β respectively according to the core structure parameters given according to actual design requirements.

[0051] Among them, the input of the defined relationship one is b / a, and the output is α; the input of the defined relationship two is c*d, and the output is β.

[0052] Among them, a is the width of the core steel sheet, b is the core aperture, c is the joint step amount between the core steel sheets, and d is the number of joints between the core steel sheets.

[0053] In this embodiment, the specific implementation methods for obtaining Relationship One and Relationship Two are not limited. For example: The corresponding additional coefficient curves representing the relationship between input and output can be drawn in advance, that is, the model functions respectively obtained by fitting according to the known aperture additional coefficient curve and the joint additional coefficient curve. Substitute the designed b / a as the input into the model function obtained by fitting the aperture additional coefficient curve, and the aperture additional coefficient α is output; similarly, substitute the designed c*d as the input into the model function obtained by fitting the joint additional coefficient curve, and the joint additional coefficient β is output. For the convenience of understanding, this application exemplarily gives the aperture additional coefficient curve and the joint additional coefficient curve respectively as Figure 3 , Figure 4 as shown.

[0054] For another example: Collect a large amount of input and output data, summarize and make a relationship table between input and output, that is, from the aperture additional coefficient table, use the designed b / a as the input and determine the corresponding aperture additional coefficient α as the output by looking up the table; similarly, from the joint additional coefficient table, use the designed c*d as the input and determine the corresponding joint additional coefficient β as the output by looking up the table; if the given input is not recorded in the table, the required input-output value can be obtained by interpolation.

[0055] Step 1.3: Combine the aperture additional coefficient α and the joint additional coefficient β according to k a =α*β*γ to obtain the iron core structure coefficient k a .

[0056] Among them, γ is the inherent deviation factor of the designed iron core structure.

[0057] Step 2: Calculate the iron core material coefficient of the standard iron core model, specifically including:

[0058] Step 2.1: Define the iron core material coefficient k b including the lamination additional coefficient H, the stacking additional coefficient H 1 and the shear additional coefficient F.

[0059] Step 2.2: According to Relationship Three between the lamination additional coefficient H and the corresponding iron core material parameters e, f, and according to the stacking additional coefficient H 1 and the corresponding iron core material parameters ρ, ρ 0 between Relationship Four, and according to Relationship Five between the shear additional coefficient F and the corresponding iron core material parameter g, calculate the corresponding lamination additional coefficient H, stacking additional coefficient H 1 and shear additional coefficient F respectively according to the iron core material parameters given according to the actual design requirements.

[0060] Among them, the input of defining Relationship Three is e and f, and the output is H=(e-2 *f) / e = e -3 *f; Define the input of relationship four as ρ and ρ 0 , and the output as H 1 = ρ 0 / ρ; Define the input of relationship five as g, and the output as F = k*g.

[0061] Among them, e is the thickness of the iron core steel sheet, f is the film thickness of the iron core steel sheet, ρ is the standard density of the iron core steel sheet, and ρ 0 is the film-containing density of the iron core steel sheet, g is the width of the cut piece of the iron core steel sheet, and k is a fixed proportionality coefficient.

[0062] In this embodiment, the specific implementation methods for obtaining relationship three, relationship four, and relationship five are not limited. For example: The corresponding additional coefficient curves can be drawn in advance to represent the relationship between the input and output, that is, the model functions respectively obtained by fitting according to the known lamination additional coefficient curve, stacking additional coefficient curve, and shearing additional coefficient curve. Substitute the designed e and f as the input into the model function obtained by fitting the lamination additional coefficient curve, and the output is the lamination additional coefficient H = (e -2 *f) / e; Similarly, substitute the designed ρ and ρ 0 as the input into the model function obtained by fitting the stacking additional coefficient curve, and the output is the stacking additional coefficient H 1 = ρ 0 / ρ; Similarly, substitute the designed g as the input into the model function obtained by fitting the shearing additional coefficient curve, and the output is the shearing stress received by the width of the cut piece F = k*g, which is simply called the shearing additional coefficient. For the convenience of understanding, the present application exemplarily gives the lamination additional coefficient curve, stacking additional coefficient curve, and shearing additional coefficient curve respectively as Figure 5 , Figure 6 shown.

[0063] For another example: Collect a large amount of data of input and output, and summarize and make a relationship table between the input and output, that is, from the lamination additional coefficient table, substitute the designed e and f as the input and determine the corresponding lamination additional coefficient H = (e -2 *f) / e as the output through table lookup; Similarly, from the stacking additional coefficient table, substitute the designed ρ and ρ 0 as the input and determine the corresponding stacking additional coefficient as H 1 = ρ 0 / ρ as the output; Similarly, from the shearing additional coefficient table, substitute the designed g as the input and determine the corresponding shearing additional coefficient F = k*g as the output through table lookup; If the given input is not recorded in the table, the required input-output value can be obtained by interpolation.

[0064] Step 2.3: According to kb = H * H 1 *F combines the lamination additional coefficient H and the stacking additional coefficient H 1 and the shear additional coefficient F to obtain the core material coefficient k b .

[0065] Step 3: Calculate the core surface pressure coefficient of the standard core model, specifically including:

[0066] According to the relationship between the core surface pressure coefficient k c and the corresponding external action parameter p, calculate the corresponding surface pressure additional coefficient k according to the external action parameter given according to the actual design requirements c .

[0067] Among them, the input of the defined relationship six is p, and the output is k c , and p is the surface pressure corresponding to the torque acting on the core steel sheet

[0068] In this embodiment, the specific implementation method for obtaining the relationship six is not limited. For example: the corresponding additional coefficient curve can be drawn in advance to represent the relationship between the input and the output, that is, the model function obtained by fitting the known surface pressure and torque additional coefficient curve. Substitute the designed p as the input into the model function obtained by fitting the surface pressure and torque additional coefficient curve, and the surface pressure additional coefficient k is output c . For the convenience of understanding, the present application exemplarily gives the surface pressure and torque additional coefficient curve as Figure 7 shown

[0069] For another example: collect a large amount of input and output data, summarize and make a relationship table between the input and the output, that is, from the surface pressure and torque additional coefficient table, use the designed p as the input to determine the corresponding surface pressure additional coefficient k by looking up the table c as the output; if the given input is not recorded in the table, the required input-output value can be obtained by interpolation

[0070] Step 4: Calculate the core anomaly coefficient of the standard core model, specifically including:

[0071] Step 4.1: Define the core anomaly coefficient k d including the environmental coefficient E and the core inherent loss coefficient L

[0072] Step 4.2: According to the relationship seven between the environmental coefficient E and the corresponding core environmental parameter t, and according to the relationship eight between the core inherent loss coefficient L and the corresponding core loss coefficient l t between them, calculate the corresponding environmental coefficient E and core inherent loss coefficient L according to the core environmental parameter and core loss coefficient given according to the actual design requirements

[0073] Among them, the input of relationship seven is t, and the output is E; the input of relationship eight is l t , and the output is L.

[0074] Among them, t is the temperature and humidity of the environment where the iron core is located, and l t is the unit iron loss during iron core assembly calculated at the current temperature and humidity of the iron core.

[0075] In this embodiment, the specific implementation methods for obtaining relationship seven and relationship eight are not limited. For example: corresponding additional coefficient curves can be drawn in advance to represent the relationship between the input and the output, that is, the model functions respectively obtained by fitting according to the known environmental coefficient curve and the assembly loss coefficient curve. Substitute the designed t as the input into the model function obtained by fitting the environmental coefficient curve, and the environmental coefficient E is output; similarly, substitute the designed l t as the input into the model function obtained by fitting the assembly loss coefficient curve, and the iron core inherent loss coefficient L is output. For the convenience of understanding, the environmental coefficient curve and the assembly loss coefficient curve are exemplarily given in the present application as Figure 8 shown, where the solid line represents the environmental coefficient curve and the dashed line represents the assembly loss coefficient curve.

[0076] For another example: collect a large amount of data of the input and the output, and summarize and make a relationship table between the input and the output, that is, from the environmental coefficient table, use the designed t as the input to determine the corresponding environmental coefficient E as the output by looking up the table; similarly, from the assembly loss coefficient table, use the designed l t as the input to determine the corresponding iron core inherent loss coefficient L as the output by looking up the table; if the given input is not recorded in the table, the required input-output values can be obtained by interpolation.

[0077] Step 4.3: Combine the environmental coefficient E and the iron core inherent loss coefficient L according to k d =E*L to obtain the iron core anomaly coefficient k d .

[0078] Step 5: Combine the calculated iron core structure coefficient k a , the iron core material coefficient k b , the iron core surface pressure coefficient k c and the iron core anomaly coefficient k d into the theoretical process coefficient A of the standard iron core model. The calculation formula is:

[0079]

[0080] Step 6: Correct the calculated theoretical process coefficient according to the process coefficient error threshold given under the model of the standard iron core model.

[0081] Among them, the process coefficient error threshold is determined by the fluctuation range of the difference between the actual process coefficient determined during actual production and the theoretical process coefficient calculated during the design process for multiple acquisitions of the standard iron core model of the same model. The actual process coefficient is obtained by manufacturing the standard iron core model of this model through laboratory standard means, conducting magnetic performance tests on the iron core, and inversely calculating the actual process coefficient of the iron core according to the iron core magnetic performance test formula in the industry. Since the standard iron core model when calculating the theoretical process coefficient A is in an ideal state, and in actual production, the abnormal coefficient varies greatly due to different weather conditions and assembly process maturity during production, the usually calculated theoretical process coefficient A is slightly smaller than the actual process coefficient. Therefore, after the model of the standard iron core model is determined, directly adding the calculated theoretical process coefficient A to the process coefficient error threshold given for this model can obtain a process coefficient correction value close to the actual process coefficient of this model.

[0082] Based on the above method to obtain the standard iron core model of the transformer, its initial process coefficient is defined to include the iron core structure coefficient k a , the iron core material coefficient k b , the iron core surface pressure coefficient k c and the iron core abnormal coefficient k d . Calculate these four types of coefficients respectively to achieve the accurate calculation of the iron core process coefficient; further define the additional coefficient terms included in each coefficient of the transformer iron core according to relevant attributes, determine the additional coefficient values corresponding to the given design parameters according to the relationship between each additional coefficient and the corresponding parameters, and then obtain each coefficient of the iron core through combination; combine each coefficient of the iron core into the theoretical process coefficient of the standard iron core model, and correct it based on the process coefficient error threshold given under the model to which the standard iron core model belongs. Finally, the corrected theoretical process coefficient of the iron core can be used as both the single-phase iron core process coefficient and the three-phase iron core process coefficient to prepare the required standard iron core model; this method constructs a standardized process with the defined coefficients of the iron core as the judgment standard for the calculation logic to enhance the stability of the iron core design, thereby providing a basis for the theoretical calculation of the iron loss performance of the transformer iron core.

[0083] It should be noted that steps 1 to 4 do not have a sequential execution order and can be carried out simultaneously. In steps 1 to 4, the fitting function method of the known curve is not limited. For example, the corresponding model function can be directly generated by existing software or obtained by existing fitting methods such as the least squares method. And the proportional coefficient k i required for correction has been added to the relevant additional coefficient curves of each defined coefficient provided in the steps, that is, α = k 1 α, β = k 2 β, and so on.

[0084] The above are only the preferred embodiments of the present application, and the present invention is not limited to the above embodiments. It can be understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for calculating the process coefficient of a transformer core, characterized in that, the method includes: Calculate the core structure coefficient k respectively a , core material coefficient k b 、Core surface pressure coefficient k c and core anomaly coefficient k d , and combined into the theoretical process coefficient of the standard core model of the transformer, where the core abnormal coefficient k d Related to the transformer use environment and inherent core loss; correcting the calculated theoretical process coefficient according to the process coefficient error threshold given under the model of the standard core model; wherein, the method for calculating the core material coefficient includes: defining that the core material coefficient includes a lamination additional coefficient, a stacking additional coefficient, and a shearing additional coefficient; According to relationship three between the lamination additional coefficient and corresponding core material parameters e and f, and according to relationship four between the stacking additional coefficient and corresponding core material parameters ρ and ρ 0 and relationship five between the shearing additional coefficient and corresponding core material parameter g, the lamination additional coefficient H, the stacking additional coefficient H 1 and the shearing additional coefficient F are respectively calculated; wherein, the input of relationship three is e and f, and the output is H = e -3 *f; the input of relationship four is ρ and ρ 0 , and the output is H 1 = ρ 0 / ρ; the input of relationship five is g, and the output is F = k*g; According to k b = H * H 1 * F, the iron core material coefficient k is obtained b ; Among them, e is the thickness of the iron core steel sheet, f is the film thickness of the iron core steel sheet, ρ is the standard density of the iron core steel sheet, ρ 0 is the film-containing density of the iron core steel sheet, g is the width of the cut piece of the iron core steel sheet, and k is a fixed proportionality coefficient; wherein, the method for calculating the core anomaly coefficient includes: defining that the core anomaly coefficient includes an environment coefficient E and a core inherent loss coefficient L; According to relationship seven between the environmental coefficient and the corresponding iron core environmental parameter t, and according to relationship eight between the iron core inherent loss coefficient and the corresponding iron core loss coefficient l t respectively calculate to obtain the environmental coefficient E and the iron core inherent loss coefficient L; According to k d = E * L, the core anomaly coefficient k is obtained d ; Among them, t is the temperature and humidity of the environment where the iron core is located, and l t is the unit iron loss during the iron core assembly calculated under the current temperature and humidity of the iron core.

2. The method for calculating the process coefficient of a transformer core according to claim 1, characterized in that, the method for calculating the core structure coefficient includes: defining that the core structure coefficient includes a hole diameter additional coefficient and a joint additional coefficient; calculating the hole diameter additional coefficient α and the joint additional coefficient β respectively according to the relationship one between the hole diameter additional coefficient and the corresponding core structure parameters a, b, and according to the relationship two between the joint additional coefficient and the corresponding core structure parameters c, d; According to k a The aperture addition coefficient α and the joint addition coefficient β are combined according to a =α*β*γ to obtain the iron core structure coefficient k a ; wherein, a is the width of the core steel sheet, b is the core hole diameter, c is the joint step amount between the core steel sheets, d is the number of joints between the core steel sheets, and γ is the inherent deviation factor of the core structure.

3. The method for calculating the process coefficient of a transformer core according to claim 2, characterized in that, the input of the relationship one is b / a, and the output is α; the input of the relationship two is c*d, and the output is β.

4. The method for calculating the process coefficient of a transformer core according to claim 1, characterized in that, Calculating the iron core surface pressure coefficient k c The method includes: Calculate k according to the relationship six between the iron core surface pressure coefficient and the corresponding external action parameter p c ; wherein, p is the surface pressure corresponding to the torque acting on the core steel sheet.

5. The method for calculating the process coefficient of a transformer core according to claim 4, characterized in that, The input of Relationship Six is p, and the output is k c .

6. The method for calculating the process coefficient of a transformer core according to claim 1, characterized in that, The input of Relationship Seven is t, and the output is E; the input of Relationship Eight is l t , and the output is L.

7. The method for calculating the process coefficient of a transformer core according to claim 1, characterized in that, The calculated iron core structure coefficient k a , the iron core material coefficient k b , the iron core surface pressure coefficient k c and the iron core anomaly coefficient k d are combined into the calculation formula of the theoretical process coefficient A of the standard iron core model as follows:

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