Multi-layer winding type Rogowski coil current transformer and preparation method thereof

Abstract

The invention relates to the technical field of current transformers, in particular to a multi-layer winding type Rogowski coil current transformer and a preparation method thereof.The preparation method includes the steps that the number of turns of first total coil winding and the number of turns of each layer of coil are calculated according to preset first framework parameters, and then the number of layers is calculated according to the number of turns of each layer of coil and the number of turns of first total coil winding; judging whether the layer number is greater than a first preset winding layer number; if the number of the winding layers is larger than the first preset winding layer number, the first framework parameter is adjusted, the number of the winding layers is recalculated according to the adjusted framework parameter, whether the recalculated number of the winding layers is larger than the second preset winding layer number or not is judged, and if the recalculated number of the winding layers is larger than the second preset winding layer number, readjustment is conducted. And preparing the current transformer according to the current winding layer number, the adjusted current skeleton parameter and the current total coil winding number of turns until the adjusted current skeleton parameter meets the condition that the current winding layer number is not greater than the current preset winding layer number, thereby greatly improving the measurement precision of the Rogowski coil current transformer.

Description

Technical Field

[0001] The present application relates to the technical field of current transformers, and in particular to a multi-layer wound Rogowski coil current transformer and a preparation method thereof. Background Art

[0002] A current transformer is a device used to measure the current in an AC circuit. It makes current measurement safer and more convenient by converting high current into a lower, easier-to-handle current. Current transformers are widely used in power systems, industrial control, instrumentation, and other fields.

[0003] In order to prevent the current transformer from magnetic saturation, a Rogowski coil current transformer is used to measure the current. For a Rogowski coil current transformer with multiple layers of coils, the measurement accuracy of the Rogowski coil current transformer is seriously affected due to the change in the cross-sectional area of ​​the coil. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a multi-layer wound Rogowski coil current transformer and a preparation method thereof, which can effectively solve the problem in the existing solution that the measurement accuracy of the Rogowski coil current transformer is seriously affected due to the change in the cross-sectional area of ​​the coil.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a multilayer wound Rogowski coil current transformer, comprising: calculating the number of winding turns of a first total coil according to electrical parameters of the current transformer and preset first skeleton parameters;

[0006] Calculate the number of turns of each layer of the coil of the current transformer according to the first skeleton parameter and the coil parameter of the current transformer;

[0007] Calculating the number of first winding layers of the current transformer according to the number of turns of each layer of coil and the number of turns of the first total coil winding;

[0008] Determining whether the first number of winding layers is greater than a first preset number of winding layers;

[0009] If the first number of winding layers is greater than the first preset number of winding layers, adjusting the first skeleton parameter to a second skeleton parameter;

[0010] Calculating the number of turns and the number of second winding layers of the second total coil according to the second skeleton parameters;

[0011] Determining whether the second number of winding layers is greater than a second preset number of winding layers;

[0012] If it is determined that the second number of winding layers is greater than the second preset number of winding layers, the skeleton parameters are readjusted until the adjusted current skeleton parameters satisfy the corresponding calculated current number of winding layers is not greater than the current preset number of winding layers;

[0013] The current transformer is prepared according to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns.

[0014] In some embodiments, before preparing the current transformer according to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns, the preparation method further includes:

[0015] Calculating the mutual inductance values ​​of each layer of coils of the current transformer and the primary current-carrying conductor;

[0016] Calculating the total mutual inductance value of the current transformer according to the mutual inductance values ​​corresponding to each layer of coils;

[0017] Calculating a theoretical output voltage of the current transformer according to a total mutual inductance value of the current transformer;

[0018] Determining whether an absolute value of a relative error between the theoretical output voltage and the rated output voltage of the current transformer is greater than a first preset value;

[0019] If the absolute value of the relative error of the rated output voltage of the current transformer is greater than a first preset value, the adjusted current skeleton parameters and / or the current total number of coil winding turns are readjusted until the absolute value of the relative error of the rated output voltage of the current transformer is not greater than the first preset value, and the final skeleton parameters and the final total number of coil winding turns are determined;

[0020] The current transformer is prepared according to the final skeleton parameters and the final total number of coil winding turns.

[0021] In some embodiments, after preparing the current transformer according to the final skeleton parameters and the final total number of coil turns, the preparation method includes:

[0022] Calculating the self-inductance value of the current transformer according to the final total number of coil winding turns;

[0023] Using a testing device to test relevant parameters of the current transformer;

[0024] The parameter error of the current transformer is calculated according to the relevant parameters and theoretical parameters.

[0025] In some embodiments, a metal shielding layer is provided between each layer of windings of the current transformer.

[0026] In some embodiments, the calculating the number of turns of the first total coil according to the electrical parameters of the current transformer and the preset first skeleton parameters includes:

[0027] The total number of coil turns is calculated using the following formula:

[0028]

[0029] Where: N1 represents the total number of coil winding turns; U 2n represents the rated output voltage of the current transformer; μ0 represents the vacuum magnetic permeability; h represents the initial height of the skeleton; I 1n represents the rated input current; f represents the rated frequency; r b represents the initial outer radius of the skeleton; r a Represents the initial inner radius of the skeleton.

[0030] In some embodiments, the number of turns of each layer of the coil of the current transformer is calculated using the following formula:

[0031]

[0032] Where: n i represents the number of coil turns in the i-th layer; i represents the i-th layer; Φ2 represents the coil diameter.

[0033] In some embodiments, the preset number of winding layers is calculated using the following formula:

[0034]

[0035] Wherein: C2 represents the preset number of winding layers; T represents the shuttle head size of the automatic winding machine.

[0036] In some embodiments, the mutual inductance between each layer of coils of the current transformer and the primary current-carrying conductor is calculated using the following formula:

[0037]

[0038] Where: M 12，i Represents the mutual inductance between the i-th layer coil and the primary current-carrying conductor.

[0039] In some embodiments, the theoretical output voltage of the current transformer is calculated using the following formula:

[0040] U2=2πfI 1n M 12 ;

[0041] Where: U2 represents the theoretical output voltage; M 12 Represents the total mutual inductance value of the current transformer.

[0042] In a second aspect, an embodiment of the present application provides a multi-layer wound Rogowski coil current transformer, wherein the multi-layer wound Rogowski coil current transformer is obtained by using at least one preparation method described in any one of the above aspects.

[0043] The embodiments of the present application have the following beneficial effects:

[0044] The preparation method of the multi-layer wound Rogowski coil current transformer of the present application first calculates the first total coil winding turns according to the electrical parameters and the preset first skeleton parameters, then calculates the coil turns of each layer, calculates the number of layers of the current transformer according to the coil turns of each layer and the first total coil winding turns, judges whether the first winding layer number is greater than the first preset winding layer number, if the judgment result is greater than the first preset winding layer number, adjusts the first skeleton parameters, recalculates the winding layer number according to the adjusted skeleton parameters, re-judges whether the winding layer number is greater than the second preset winding layer number, if the winding layer number is greater than the second preset winding layer number, re-adjusts the skeleton parameters. The number is adjusted, and the calculation is performed again according to the adjusted skeleton parameters. The comparison is made again according to the calculated results until the adjusted current skeleton parameters satisfy that the current number of winding layers is not greater than the current preset number of winding layers. According to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns, a current transformer is prepared. The application first calculates the number of coil turns of each layer using the skeleton parameters, and then calculates the number of winding layers according to the number of coil turns of each layer and the total number of coil winding turns, and determines whether the number of winding layers meets the requirements, thereby avoiding the influence of different cross-sectional areas of each layer of coils on the current transformer, and greatly improving the measurement accuracy of the Rogowski coil current transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A first process schematic diagram of a method for preparing a multi-layer wound Rogowski coil current transformer according to an embodiment of the present application is shown;

[0047] Figure 2 A second process diagram of the method for preparing a multi-layer wound Rogowski coil current transformer according to an embodiment of the present application is shown;

[0048] Figure 3 A third process diagram of the method for preparing a multi-layer wound Rogowski coil current transformer according to an embodiment of the present application is shown;

[0049] Figure 4 A schematic diagram showing the comparison between the output voltage of the conventional design of the current transformer of the embodiment of the present application at different current values ​​and the output voltage of the present invention and the theoretical voltage is shown. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0051] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0052] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0053] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0054] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0055] Taking into account the problem that the measurement accuracy of a Rogowski coil current transformer is seriously affected by changes in the cross-sectional area of ​​the coil in the prior art, the present application provides a multi-layer wound Rogowski coil current transformer and a preparation method thereof. The present application first calculates the number of turns of each layer of coil using skeleton parameters, and then calculates the number of winding layers according to the number of turns of each layer of coil and the total number of winding turns of the coil, and determines whether the number of winding layers meets the requirements, thereby avoiding the influence of different cross-sectional areas of each layer of coil on the current transformer, and greatly improving the measurement accuracy of the Rogowski coil current transformer.

[0056] The preparation method of the multi-layer wound Rogowski coil current transformer is described below in conjunction with some specific embodiments.

[0057] Figure 1 A schematic flow chart of a method for preparing a multilayer wound Rogowski coil current transformer according to an embodiment of the present application is shown. Exemplarily, the method comprises steps S101-S109:

[0058] Step S101: Calculate the number of turns of the first total coil according to the electrical parameters of the current transformer and the preset first skeleton parameters.

[0059] The total number of coil turns can be calculated based on the electromagnetic induction principle of the current transformer.

[0060] Specifically, the electrical parameters of the current transformer include the rated frequency of the current transformer, the rated input current of the current transformer and the rated output voltage of the current transformer, etc. The electrical parameters of the current transformer can be set according to the actual application. By way of example, the rated frequency of the current transformer is 50HZ, the rated input current of the current transformer is 125A, and the rated output voltage of the current transformer is 100mV.

[0061] The skeleton shape of the current transformer can be preliminarily set according to the actual application situation. The skeleton of the current transformer can be any kind of skeleton. Exemplarily, the skeleton of the current transformer is a rectangular cross-section annular rigid skeleton. The parameters of the skeleton include the height of the skeleton, the inner radius of the skeleton and the outer radius of the skeleton. Specifically, the inner radius of the skeleton is the radius of the inner surface of the skeleton, that is, the minimum radius of the coil winding area; the outer radius of the skeleton refers to the radius of the outer surface of the skeleton, that is, the maximum radius of the coil winding area. The first skeleton parameter can be set according to the actual application situation. For example, the geometric parameter requirements of the current transformer in this embodiment are: the inner radius of the skeleton is greater than or equal to 5.5mm, the outer radius of the skeleton is less than or equal to 12mm, and the height of the skeleton is less than or equal to 20mm. Exemplarily, the first skeleton parameters are: the initial inner radius of the skeleton is 8mm, the initial outer radius of the skeleton is 10mm, and the initial height of the skeleton is 16mm.

[0062] For example, the total number of coil turns can be calculated using the following formula:

[0063]

[0064] Where: N1 represents the total number of coil winding turns; U 2n represents the rated output voltage of the current transformer; μ0 represents the vacuum magnetic permeability, and the value of μ0 is 4π×10 -7 H / m; h represents the initial height of the skeleton; I 1n represents the rated input current; f represents the rated frequency; r b Represents the initial outer radius of the skeleton; ra Represents the initial inner radius of the skeleton. Substituting the parameters of the above example into the formula, we can get N1≈3566, that is, the number of turns of the first total coil is 3566 turns.

[0065] Step S102: Calculate the number of turns of each layer of the coil of the current transformer according to the first skeleton parameter and the coil parameter of the current transformer.

[0066] Specifically, the coil parameters of the current transformer include the diameter of the coil, etc. The diameter of the coil can be set according to actual application conditions. Exemplarily, the coil diameter is 0.15 mm.

[0067] For example, the following formula can be used to calculate the number of turns of each layer of coil:

[0068]

[0069] Where: n i Represents the number of coil turns in the i-th layer; i represents the i-th layer; Φ2 represents the coil diameter. Substituting the parameters of each example into the formula, we get: the number of coil turns in the first layer n1≈332, the number of coil turns in the second layer n2≈326, the number of coil turns in the third layer n3≈321, the number of coil turns in the fourth layer n4≈315, the number of coil turns in the fifth layer n5≈310, the number of coil turns in the sixth layer n6≈305, the number of coil turns in the seventh layer n7≈299, the number of coil turns in the eighth layer n8≈294, the number of coil turns in the ninth layer n9≈288, the number of coil turns in the tenth layer n 10 ≈283, the number of turns of the eleventh coil is n 11 ≈277.

[0070] Step S103: Calculate the number of first winding layers of the current transformer according to the number of turns of each coil layer and the number of turns of the first total coil winding.

[0071] The number of turns of the first total coil is N1≈3566, and the sum of the turns of the above-mentioned coil layers is 3350. It can be seen that the number of the first winding layers is 12 layers.

[0072] Step S104: determining whether the first number of winding layers is greater than a first preset number of winding layers.

[0073] The preset number of winding layers can be obtained based on the frame parameters, coil parameters and parameters of the automatic winding machine. For example, the preset number of winding layers can be calculated using the following formula:

[0074]

[0075] Wherein: C2 represents the preset number of winding layers; T represents the shuttle head size of the automatic winding machine. Substituting the parameters of each example into the formula, the first preset number of winding layers is 11.7. It can be seen that the first number of winding layers is greater than the first preset number of winding layers.

[0076] Step S105: If the first number of winding layers is greater than the first preset number of winding layers, adjusting the first skeleton parameter to the second skeleton parameter.

[0077] The first number of winding layers is greater than the first preset number of winding layers, that is, greater than the frame window coefficient threshold, and the coil cannot be completely wound on the frame.

[0078] Specifically, the second skeleton parameters are generated by adjusting one or more parameters among the height of the skeleton, the inner radius of the skeleton and the outer radius of the skeleton in the first skeleton parameters. Specifically, the inner radius of the skeleton is reduced to reduce the total number of coil winding turns, and the outer radius of the skeleton and / or the height of the skeleton are increased to increase the preset number of winding layers.

[0079] Step S106: Calculate the second total coil winding turns and the second winding layers according to the second skeleton parameters.

[0080] According to the second skeleton parameters and the above formula, the total number of coil winding turns is recalculated as the second total number of coil winding turns, the number of coil turns of each layer is recalculated according to the second skeleton parameters and the above formula, and the number of winding layers is recalculated according to the second total number of coil winding turns and the recalculated number of coil turns of each layer as the second number of winding layers.

[0081] Step S107: Determine whether the second number of winding layers is greater than the second preset number of winding layers.

[0082] It can be understood that if the second skeleton parameter is generated by adjusting the inner radius of the skeleton by the first skeleton parameter, then the second number of winding layers is generated by adjusting the inner radius of the skeleton. If the second skeleton parameter is compared with the first skeleton parameter and the inner radius of the skeleton is the same, then the second preset number of winding layers is the same as the first preset number of winding layers.

[0083] If the second number of winding layers is not greater than the second preset number of winding layers, it means that the second number of winding layers meets the requirements, and a current transformer is prepared according to the second skeleton parameters, the second number of winding layers and the second total number of coil winding turns.

[0084] Step S108: If it is determined that the second number of winding layers is greater than the second preset number of winding layers, readjust the skeleton parameters until the adjusted current skeleton parameters satisfy that the current number of winding layers is not greater than the preset number of winding layers.

[0085] If it is determined that the second number of winding layers is greater than the second preset number of winding layers, the skeleton parameters are readjusted according to the method in step S105 to generate third skeleton parameters, and the third total number of coil winding turns and the third number of winding layers are calculated using the third skeleton parameters to determine whether the third number of winding layers is greater than the third preset number of winding layers. If it is determined that the second number of winding layers is greater than the third preset number of winding layers, continue to adjust, recalculate, and recompare until the adjusted current skeleton parameters satisfy that the current number of winding layers is not greater than the preset number of winding layers.

[0086] Step S109: preparing a current transformer according to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns.

[0087] Demonstratively, according to the parameters of the above example, the current number of winding layers is 9 layers, the adjusted current skeleton parameters are 7.5mm inner radius of the skeleton, 10mm outer radius of the skeleton, 16mm skeleton height, and the current total number of coil winding turns is 2770 turns. The current transformer is prepared using the above parameters. Demonstratively, a groove with a depth of 1.25mm and a width of 2mm is first dug in the center of the outer wall of the skeleton. When the coil is wound using an automatic winding machine, one turn is first wound in the groove to offset the interference of the external magnetic field in the vertical direction, and then 2770 turns are wound along the skeleton in the opposite direction. A metal shielding shell can be added to the surface of the current transformer according to the actual application. The shielding shell should be able to completely wrap the skeleton and winding of the Rogowski coil. The cross-section of the metal shielding shell is C-shaped and the fracture air gap is at its outer edge.

[0088] In this embodiment, the total number of coil winding turns and the number of winding layers are preliminarily determined according to the electromagnetic induction principle of the current transformer, and the number of winding layers is compared with the preset number of winding layers. According to the comparison result, it is judged whether the winding exceeds the skeleton, and the skeleton parameters are adjusted and re-compared until the current number of winding layers is not greater than the current preset number of winding layers, ensuring that the number of winding turns is within the physical and electrical limitations of the skeleton, making the coil structure more compact and firm, and at the same time being able to ensure uniform magnetic field distribution, greatly improving the measurement accuracy of the Rogowski coil current transformer.

[0089] In one embodiment, Figure 2 Another schematic flow chart of a method for preparing a multilayer wound Rogowski coil current transformer according to an embodiment of the present application is shown. Based on the above embodiment, before step S109, the preparation method further includes:

[0090] Step S201: Calculate the mutual inductance between each layer of coil of the current transformer and the primary current-carrying conductor.

[0091] The mutual inductance values ​​of each layer of coils of the current transformer and the primary current-carrying conductor are calculated according to various parameters. For example, assuming there are four layers of coils, then the mutual inductance values ​​of the first to fourth layers of coils and the primary current-carrying conductor need to be calculated, and four mutual inductance values ​​will be obtained.

[0092] For example, the mutual inductance between any layer of coil of the current transformer and the primary current-carrying conductor can be calculated using the following formula:

[0093]

[0094] Where: M 12,irepresents the mutual inductance between the i-th layer coil and the primary current-carrying conductor. The parameters of each example can be substituted into the formula to calculate the mutual inductance between each layer coil and the primary current-carrying conductor.

[0095] Step S202: Calculate the total mutual inductance of the current transformer according to the mutual inductance corresponding to each layer of coils.

[0096] Specifically, the mutual inductance values ​​corresponding to the coils of each layer are added in sequence to obtain the total mutual inductance value of the current transformer.

[0097] Specifically, according to the 9 winding layers in the above example, the mutual inductance value of layer i is recorded as M 12，i , the total mutual inductance value M of the current transformer is exemplarily 12 =M 12，1 +M 12，2 +M 12，3 +M 12，4 +M 12，5 +M 12，6 +M 12，7 +M 12，8 +M 12，9 , where M 12，1 Represents the mutual inductance between the first layer and the primary current-carrying conductor, M 12，2 Indicates the mutual inductance between the second layer and the primary current-carrying conductor, M 12，3 Indicates the mutual inductance between the third layer and the primary current-carrying conductor, M 12，4 Represents the mutual inductance between the fourth layer and the primary current-carrying conductor, M 12，5 Indicates the mutual inductance between the fifth layer and the primary current-carrying conductor, M 12.6 Represents the mutual inductance between the sixth layer and the primary current-carrying conductor, M 12，7 Represents the mutual inductance between the seventh layer and the primary current-carrying conductor, M 12，8 Represents the mutual inductance between the eighth layer and the primary current-carrying conductor, M 12.9 represents the mutual inductance between the ninth layer and the primary current-carrying conductor. The parameters of the above example can be substituted into the formula to calculate the total mutual inductance.

[0098] Step S203: Calculate the theoretical output voltage of the current transformer according to the total mutual inductance value of the current transformer.

[0099] For example, the theoretical output voltage of the current transformer can be calculated using the following formula:

[0100] U2=2πfI 1n M 12 ;

[0101] Among them: U2 represents the theoretical output voltage; M 12 represents the total mutual inductance of the current transformer. The parameters of the above example can be substituted into the formula to calculate the theoretical output voltage.

[0102] Step S204: determine whether the absolute value of the relative error between the theoretical output voltage and the rated output voltage of the current transformer is greater than a first preset value.

[0103] The first preset value may be set according to actual application conditions. Exemplarily, the first preset value is less than 0.1%.

[0104] For example, the relative error between the theoretical output voltage and the rated output voltage of the current transformer can be calculated using the following formula:

[0105]

[0106] Where: ΔU represents the relative error between the theoretical output voltage and the rated output voltage of the current transformer, U 2n represents the rated output voltage of the current transformer, which is 100mv. The parameters in the above example can be substituted into the formula to calculate the relative error.

[0107] Step S205: If the absolute value of the relative error of the rated output voltage of the current transformer is greater than the first preset value, readjust the adjusted current skeleton parameters and / or the current total number of coil winding turns until the absolute value of the relative error of the rated output voltage of the current transformer is not greater than the first preset value, and determine the final skeleton parameters and the final total number of coil winding turns.

[0108] It can be understood that if the absolute value of the relative error of the rated output voltage of the current transformer calculated based on the adjusted current skeleton parameters and the current total coil winding turns is not greater than the first preset value, the adjusted current skeleton parameters and the current total coil winding turns are set as the final skeleton parameters and the final total coil winding turns. If the absolute value of the relative error of the rated output voltage of the current transformer calculated based on the adjusted current skeleton parameters and the current total coil winding turns is greater than the first preset value, the skeleton parameters and / or the total coil winding turns will continue to be adjusted, and the rated output voltage of the current transformer will be calculated again based on the re-adjusted skeleton parameters and the total coil winding turns, until the absolute value of the relative error of the rated output voltage of the current transformer is greater than the first preset value.

[0109] Specifically, by adjusting the adjusted current skeleton parameters and / or the current total number of coil winding turns, only one parameter can be adjusted, or multiple parameters can be adjusted. Demonstratively, by reducing the total number of coil winding turns, the mutual inductance between the coil and the primary current-carrying conductor is reduced, thereby reducing the output voltage of the mutual inductor. By lowering the skeleton height, the total number of coil winding turns and the number of winding layers are adjusted.

[0110] Step S206: preparing a current transformer according to the final frame parameters and the final total number of coil winding turns.

[0111] Exemplarily, the final frame height is 15 mm, the total number of coil turns is 2038, and the number of winding layers is 7.

[0112] In this embodiment, the mutual inductance value between each layer of coils and the primary current-carrying conductor is calculated according to the electromagnetic field theory of the current transformer, and the total mutual inductance value is calculated according to the mutual inductance value between each layer of coils and the primary current-carrying conductor. The theoretical output voltage of the current transformer is calculated using the total mutual inductance value, and the total number of winding turns and / or skeleton parameters of the current transformer are adjusted according to the absolute value of the relative error between the theoretical output voltage and the rated output voltage of the current transformer, so that the error between the theoretical output voltage and the rated output voltage is as small as possible, avoiding the influence of the current transformer on the current transformer due to the different magnetic fluxes received by the coils of each layer, thereby greatly improving the measurement accuracy of the current transformer.

[0113] In one embodiment, Figure 3 Another schematic flow chart of a method for preparing a multilayer wound Rogowski coil current transformer according to an embodiment of the present application is shown. Based on the above embodiment, after step S206, the preparation method further includes:

[0114] Step S301: Calculate the self-inductance of the current transformer according to the final total number of coil winding turns.

[0115] For example, the self-inductance of the current transformer can be calculated using the following formula:

[0116] L2=N1M 12 ;

[0117] Where: L2 represents the self-inductance value; M 12 It represents the total mutual inductance of the current transformer, and N1 represents the final total number of coil winding turns.

[0118] Step S302: Use a testing device to test relevant parameters of the current transformer.

[0119] Use a low-frequency LCR digital bridge to measure the self-inductance of the coil or a Rogowski coil test platform to measure the output voltage of the coil. Demonstration, use an LCR digital bridge, the measurement accuracy of the LCR digital bridge is higher than 0.1%, the two clamps of the bridge clamp the two output ends of the Rogowski coil current transformer respectively, test the inductance multiple times and take the average value.

[0120] Step S303: Calculate the parameter error of the current transformer according to the relevant parameters and theoretical parameters.

[0121] Calculate the relative error between the measured value and the theoretical value. Figure 4A schematic diagram comparing the output voltage of a conventional current transformer at different current values ​​and the output voltage of the present invention with the theoretical voltage is shown. Furthermore, the Rogowski coil is graded according to the accuracy of the current transformer, and exemplary grades are graded according to specifications such as ±0.5%, ±1.0%, and ±2.0%.

[0122] In this embodiment, after the current transformer is prepared, the measurement equipment is used to measure and calculate the relative error, which can verify the performance of the current transformer, ensure the reliability and accuracy of the current transformer, and ensure that the current transformer complies with relevant standards and specifications.

[0123] It is worth noting that the values ​​of the above parameters are only examples and can be adaptively adjusted according to specific circumstances.

[0124] In one embodiment, based on the above embodiment, a metal shielding layer is provided between each layer of windings of the current transformer.

[0125] It is understandable that the metal shielding layer can be any metal. Exemplarily, the metal shielding layer is an aluminum foil shielding layer. Furthermore, insulating tape is provided between each layer of windings of the current transformer.

[0126] In this embodiment, a metal shielding layer is arranged between each layer of winding of the current transformer. The metal shielding layer can effectively suppress the interference of the external electromagnetic field and the mutual interference between the internal windings, thereby improving the reliability and stability of the current transformer, and at the same time can evenly distribute the magnetic field and improve the measurement accuracy.

[0127] The embodiment of the present application further provides a multi-layer wound Rogowski coil current transformer. Exemplarily, the multi-layer wound Rogowski coil current transformer is obtained by the above-mentioned preparation method.

[0128] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or the flow diagram, and the combination of boxes in the structure diagram and / or the flow diagram, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0129] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0130] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application.

[0131] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for preparing a multi-layer wound Rogowski coil current transformer, characterized in that: include: Calculating the number of turns of the first total coil according to the electrical parameters of the current transformer and the preset first skeleton parameters; Calculate the number of turns of each layer of the coil of the current transformer according to the first skeleton parameter and the coil parameter of the current transformer; Calculating the number of first winding layers of the current transformer according to the number of turns of each layer of coil and the number of turns of the first total coil winding; Determining whether the first number of winding layers is greater than a first preset number of winding layers; If the first number of winding layers is greater than the first preset number of winding layers, adjusting the first skeleton parameter to a second skeleton parameter; Calculating the number of turns and the number of second winding layers of the second total coil according to the second skeleton parameters; Determining whether the second number of winding layers is greater than a second preset number of winding layers; If it is determined that the second number of winding layers is greater than the second preset number of winding layers, the skeleton parameters are readjusted until the adjusted current skeleton parameters satisfy the corresponding calculated current number of winding layers is not greater than the current preset number of winding layers; The current transformer is prepared according to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns.

2. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 1, characterized in that: Before preparing the current transformer according to the current number of winding layers, the adjusted current skeleton parameters and the current total number of coil winding turns, the preparation method further includes: Calculating the mutual inductance values ​​of each layer of coils of the current transformer and the primary current-carrying conductor; Calculating the total mutual inductance value of the current transformer according to the mutual inductance values ​​corresponding to each layer of coils; Calculating a theoretical output voltage of the current transformer according to a total mutual inductance value of the current transformer; Determining whether an absolute value of a relative error between the theoretical output voltage and the rated output voltage of the current transformer is greater than a first preset value; If the absolute value of the relative error of the rated output voltage of the current transformer is greater than a first preset value, the adjusted current skeleton parameters and / or the current total number of coil winding turns are readjusted until the absolute value of the relative error of the rated output voltage of the current transformer is not greater than the first preset value, and the final skeleton parameters and the final total number of coil winding turns are determined; The current transformer is prepared according to the final skeleton parameters and the final total number of coil winding turns.

3. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 2, characterized in that: After the current transformer is prepared according to the final skeleton parameters and the final total number of coil winding turns, the preparation method includes: Calculating the self-inductance value of the current transformer according to the final total number of coil winding turns; Using a testing device to test relevant parameters of the current transformer; The parameter error of the current transformer is calculated according to the relevant parameters and theoretical parameters.

4. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 1, characterized in that: A metal shielding layer is arranged between each layer of windings of the current transformer.

5. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 2, characterized in that: Calculating the number of turns of the first total coil according to the electrical parameters of the current transformer and the preset first skeleton parameters includes: The total number of coil turns is calculated using the following formula: Where: N1 represents the total number of coil winding turns; U 2n represents the rated output voltage of the current transformer; μ0 represents the vacuum magnetic permeability; h represents the initial height of the skeleton; I 1n represents the rated input current; f represents the rated frequency; r b represents the initial outer radius of the skeleton; r a Represents the initial inner radius of the skeleton.

6. The method for preparing the multi-layer wound Rogowski coil current transformer according to claim 5, It is characterized in that The number of turns of each layer of coil of the current transformer is calculated using the following formula: Where: n i represents the number of coil turns in the i-th layer; i represents the i-th layer; Φ2 represents the coil diameter.

7. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 6, characterized in that: The preset number of winding layers is calculated using the following formula: Wherein: C2 represents the preset number of winding layers; T represents the shuttle head size of the automatic winding machine.

8. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 7, characterized in that: The mutual inductance between each layer of coil of the current transformer and the primary current-carrying conductor is calculated using the following formula: Where: M 12,i Represents the mutual inductance between the i-th layer coil and the primary current-carrying conductor.

9. The method for preparing a multi-layer wound Rogowski coil current transformer according to claim 8, characterized in that: The theoretical output voltage of the current transformer is calculated using the following formula: U2=2πfI 1n M 12 ; Where: U2 represents the theoretical output voltage; M 12 Represents the total mutual inductance value of the current transformer.

10. A multi-layer wound Rogowski coil current transformer, characterized in that: The multi-layer wound Rogowski coil current transformer is obtained by the preparation method described in any one of claims 1 to 9.

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