A coupling calculation method for transformer core clamping force and lamination coefficient

Abstract

The present invention discloses a coupling calculation method for transformer core clamping force and lamination coefficient, which relates to the technical field of transformer design. The method comprises: regulating the clamping force acting on different positions of the transformer core under standard surface pressure to obtain the optimal clamping force distribution principle and the corresponding surface pressure; finding the pending lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle; and performing transformer core thickness testing under the optimal clamping force distribution principle to screen the optimal lamination coefficient from the pending lamination coefficients. The method proposes a logical relationship between the clamping force and the lamination coefficient of the transformer core at this stage, that is, by regulating the clamping force, the optimal lamination coefficient that meets the design requirements is output, which reduces the factory customer complaints caused by the influence of the lamination coefficient and also enhances the stability of the core design.

Description

Technical Field

[0001] The invention relates to the technical field of transformer design, in particular to a coupling calculation method for transformer core clamping force and lamination coefficient. Background Art

[0002] The transformer core is made of stacked silicon steel sheets, and the manufacturing process of silicon steel sheets is relatively complicated. The uneven thickness of silicon steel sheets caused by the coating process is one of the main reasons for the air gap between the silicon steel sheets after stacking. In addition to the coating process, another main reason for the uneven size of the air gap between silicon steel sheets is the clamping force provided by the fasteners on the clamps used to fix the stacked silicon steel sheets. However, since most manufacturers focus on production efficiency, they often ignore the clamping force of the clamps, resulting in weak control of the air gap, affecting the stacking coefficient and effective cross-sectional area of ​​the transformer core design, thereby reducing the magnetic properties of the transformer core and affecting the production quality of the transformer core.

[0003] At present, the influence of clamping force on the stacking factor is not taken into account in the design of existing transformer cores. That is, there is no standardized calculation logic for manufacturers to use. As a result, the stacking factor error of the transformer cores delivered at the factory is large, causing the magnetic properties of the transformer cores to exceed the standard, and the number of factory customer complaints caused by this has always remained high. Summary of the invention

[0004] In view of the above problems and technical requirements, the inventors have proposed a coupling calculation method for the clamping force of the transformer core and the lamination coefficient, and proposed a logical relationship between the clamping force and the lamination coefficient of the transformer core at the current stage, that is, by adjusting the clamping force, the optimal lamination coefficient that meets the design requirements is output. The technical solution of the present invention is as follows:

[0005] A coupling calculation method for transformer core clamping force and lamination coefficient comprises the following steps:

[0006] Under standard surface pressure, the clamping force acting on different positions of the transformer core is adjusted to obtain the optimal clamping force distribution principle and the corresponding surface pressure;

[0007] Find the undetermined lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle;

[0008] The transformer core thickness test is carried out under the principle of optimal clamping force distribution to screen out the optimal lamination coefficient from the pending lamination coefficients.

[0009] A further technical solution is to adjust the clamping force acting on different positions of the transformer core under the standard surface pressure to obtain the optimal clamping force distribution principle and the corresponding surface pressure, including:

[0010] The total clamping force corresponding to the standard surface pressure is distributed to the screws corresponding to the transformer core according to a preset ratio, wherein the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener;

[0011] Under the preset conditions, adjust the torque of each screw and keep the standard surface pressure unchanged until the clamping force distribution at different positions of the transformer core measured in real time is close to the calculated theoretical clamping force. It is considered that the current torque of each screw matches the core design application scenario.

[0012] The current torque of each screw is converted into the corresponding clamping force to obtain the optimal clamping force distribution principle, and the surface pressure corresponding to the current clamping force is calculated;

[0013] The preset condition is to make the lamination thickness of the transformer core vary uniformly.

[0014] A further technical solution is that the calculation of the theoretical clamping force includes:

[0015] Under the permissible environment of core design, the theoretical clamping force is calculated based on the actually selected screw-related parameters and the actually applied torque; wherein the screw-related parameters include: the pitch of the screw or bolt thread, the average friction coefficient between the thread and the head support, the thread median diameter of the screw or bolt thread, and the effective diameter of the friction torque in the screw head bracket or the nut bracket.

[0016] A further technical solution is to find a pending lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle, including:

[0017] The standard lamination coefficient calculated under the standard surface pressure is regarded as the lamination coefficient calculated under the surface pressure corresponding to the optimal clamping force distribution principle;

[0018] According to the relationship between the surface pressure and the discrete stacking coefficient, the surface pressure corresponding to the optimal clamping force distribution principle is used to find the discrete stacking coefficient close to the standard stacking coefficient from the discrete stacking coefficient as the undetermined stacking coefficient.

[0019] A further technical solution is to test the transformer core thickness under the principle of optimal clamping force distribution to select the optimal lamination coefficient from the undetermined lamination coefficients, including:

[0020] According to the relationship between the surface pressure and the discrete lamination coefficient, the surface pressure corresponding to each undetermined lamination coefficient is obtained respectively;

[0021] For each undetermined lamination coefficient, the total clamping force corresponding to the surface pressure is distributed to the screw corresponding to the transformer core according to the optimal clamping force distribution principle, wherein the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener;

[0022] Under the preset conditions, the torque of each screw is fine-tuned and the surface pressure is kept constant. The thickness distribution of the transformer core measured in real time is compared with the core design thickness. The undetermined lamination coefficient that meets the thickness design requirements is retained, and the highest value is selected as the optimal lamination coefficient output;

[0023] The preset condition is to make the lamination thickness of the transformer core vary uniformly.

[0024] Its further technical solution is that the method further comprises:

[0025] The stacking coefficient of the transformer core is calculated in the horizontal and vertical states, and the relationship between the surface pressure and the discrete stacking coefficient is obtained, which is described as follows: with the increase of the surface pressure, the stacking coefficient first increases to the maximum value and then decreases to the minimum value. The maximum and minimum values ​​fluctuate in the range of [0,1], and the stacking coefficient is a discrete value, while the surface pressure is a continuous value.

[0026] A further technical solution is that the calculation of the standard lamination coefficient includes, under the standard surface pressure:

[0027] Calculate the coating thickness h1 of a single steel sheet of the transformer core, and calculate the standard lamination factor based on L0 = a(h2-h1) / H;

[0028] Among them, a is the number of laminations of the core steel sheet, h2 is the thickness of a single steel sheet, and H is the total thickness of all steel sheets involved in the lamination under standard surface pressing.

[0029] A further technical solution is to calculate the coating thickness of a single steel sheet of the transformer core, including:

[0030] According to the density, mass and thickness of a single steel sheet, the coating thickness of the steel sheet can be inferred using the density formula.

[0031] The beneficial technical effects of the present invention are:

[0032] This method proposes a logical relationship between the clamping force and the stacking factor of the transformer core at this stage, that is, the clamping force is adjusted under the standard surface pressure to obtain the optimal clamping force distribution principle and the surface pressure corresponding to the optimal clamping force, so as to find the undetermined stacking factor close to the standard stacking factor, and the transformer core thickness test is carried out under the optimal clamping force distribution principle to screen out the optimal stacking factor that meets the thickness design requirements from the undetermined stacking factor, so that the designed transformer core can control the delivered stacking factor when leaving the factory, thereby reducing the factory customer complaints caused by poor stacking factor design, and also enhancing the stability of the core design, providing a basis for the theoretical calculation of the iron loss performance of the transformer core. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1It is a flow chart of the coupling calculation method of transformer core clamping force and lamination coefficient provided in this application.

[0034] Figure 2 It is a curve diagram of the relationship between surface pressure and discrete lamination coefficient provided in this application. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0036] Please refer to Figure 1 As shown, this embodiment provides a coupling calculation method for transformer core clamping force and lamination coefficient, comprising the following steps:

[0037] Step 1: Under the standard surface pressure, adjust the clamping force acting on different positions of the transformer core to obtain the optimal clamping force distribution principle and the corresponding surface pressure.

[0038] At this time, the yoke of the transformer core is placed between the upper clamp and the lower clamp, and is clamped by the fasteners arranged on the yoke, and torque is applied to each screw in the fastener, so that the fastener provides a clamping force to the yoke, thereby acting on the corresponding position of the transformer core to obtain a stable surface pressure. When designing the transformer core, the four parts of the silicon steel sheet, namely the plate length, plate width, plate density and plate thickness, are considered. Among them, the plate length and plate width are designed to ensure the magnetic density of the core. In actual production, their inherent errors and optimization are inevitable. Under the premise that the plate density is relatively stable, the plate thickness will be affected by the surface pressure, thereby causing changes in the lamination coefficient. The surface pressure is controlled by the clamping force, so the following steps focus on the logical relationship between the clamping force and the lamination coefficient.

[0039] The specific steps include the following:

[0040] Step 1.1: Allocate the total clamping force corresponding to the standard surface pressure to the screws corresponding to the transformer core according to a preset ratio.

[0041] Among them, the total clamping force corresponding to the standard surface pressure can be converted through the relationship between the clamping force, the relative area between the core and the clamp and the surface pressure. The industry-specified standard surface pressure is usually 0.15Mpa.

[0042] The distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener.

[0043] Optionally, the preset ratio is generally 1:2:1, which is distributed according to side screw: through screw: side screw.

[0044] Step 1.2: Under the preset conditions, adjust the torque of each screw and keep the standard surface pressure unchanged, measure the clamping force distribution at different positions of the transformer core in real time, until the measured clamping force is close to the calculated theoretical clamping force, then it is considered that the torque of each screw matches the core design application scenario. The closeness here usually means that the measured clamping force is infinitely close to the theoretical clamping force, but the difference between the two is allowed as long as it is within the specified error range. It should be understood that the meaning of closeness in the following steps is the same as here.

[0045] It should be noted that the yoke clamping force can be adjusted at a maximum of 0.1-1.2Mpa surface pressure.

[0046] <1> Methods for calculating the theoretical clamping force include:

[0047] Under the permissible environment of the core design, according to the actual screw parameters selected and the actual applied torque M A (Unit: Nm) Calculate the theoretical clamping force F M (Unit: N). Among them, the screw-related parameters include: the pitch P of the screw or bolt thread (unit: mm), the average friction coefficient μ between the thread and the head support GES , the thread pitch diameter D2 (in mm) of the screw or bolt thread, and the effective diameter D of the friction torque in the screw head bracket or nut bracket KM (Unit: mm). Based on the above parameters, the calculation formula given in this embodiment is:

[0048]

[0049] Among them, D KM =(D B +D M ) / 2,D B is the hole diameter of the screw or bolt thread, D M is the diameter of the nut bracket.

[0050] <2> The preset condition set in the present application is to make the thickness of the laminations of the transformer core vary uniformly.

[0051] Optionally, this embodiment uses a laser sensor to monitor the change in stack thickness and uses an optical fiber strain sensor to monitor the clamping force at different positions of the transformer core.

[0052] Step 1.3: Convert the current torque of each screw into the corresponding clamping force to obtain the optimal clamping force distribution principle, and calculate the surface pressure corresponding to the current clamping force (ie, the current torque).

[0053] Due to factors such as assembly and environment, there is a certain difference between the output surface pressure and the standard surface pressure.

[0054] Step 2: Find the undetermined lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle. Specifically, it includes the following steps:

[0055] Step 2.1: The standard stacking factor calculated under the standard surface pressure is regarded as the stacking factor calculated under the surface pressure corresponding to the optimal clamping force distribution principle.

[0056] The method for calculating the standard lamination factor includes: calculating the coating thickness h1 of a single steel sheet of the transformer core under the standard surface pressure, and obtaining the standard lamination factor according to L0=a(h2-h1) / H.

[0057] Among them, a is the number of laminations of the core steel sheet, h2 is the thickness of a single steel sheet, and H is the total thickness of all steel sheets involved in the lamination under standard surface pressing.

[0058] The method for calculating the coating thickness h1 includes: according to the density, mass and thickness of a single steel sheet, the coating thickness of the steel sheet is inferred according to the density formula. Specifically, the density and mass of a single film-containing steel sheet are calculated by the density formula to obtain the volume of the film-containing steel sheet. Since the length and width information of the steel sheet (plate) has been determined in step 1, the thickness of the film-containing steel sheet can be calculated, and the coating thickness of the steel sheet can be obtained by subtracting the thickness of the plate.

[0059] Step 2.2: According to the relationship between the surface pressure and the discrete stacking coefficient, use the surface pressure corresponding to the optimal clamping force distribution principle to find a discrete stacking coefficient close to the standard stacking coefficient L0 from the discrete stacking coefficients as the undetermined stacking coefficient, that is, the discrete stacking coefficients within the specified range of L0±α can be regarded as discrete stacking coefficients close to L0.

[0060] In this embodiment, it also includes: calculating the stacking coefficient of the transformer core in the horizontal state and the vertical state, so as to obtain the relationship between the surface pressure and the discrete stacking coefficient, which is described as: as the surface pressure increases, the stacking coefficient first increases to the maximum value, and then decreases to the minimum value, and the stacking coefficient is a discrete value, and the surface pressure is a continuous value, wherein the maximum value and the minimum value fluctuate in the range of [0,1]. In this embodiment, the preferred maximum value is 1 and the minimum value is 0, then the discrete stacking coefficient varies in the range of [0,1]. Specifically, the transformer core is in a horizontal state when the stacking is completed, at which time there is almost no surface pressure. The core is erected on a turning table, and then the core is in a vertical state. During the turning process, high surface pressure is required to maintain the core stably upright, and then the surface pressure needs to be regulated to restore it to the standard surface pressure state; the relationship between the surface pressure and the corresponding stacking coefficient in this process is recorded, so as to establish a discrete stacking coefficient curve or a discrete stacking coefficient table. The present application exemplarily gives a discrete stacking coefficient curve such as Figure 2 shown.

[0061] Taking the discrete stacking coefficient curve as an example, by substituting the surface pressure corresponding to the optimal clamping force distribution principle into the curve, it can be determined that L0 corresponding to the surface pressure will inevitably appear near a certain value of the curve, and the discrete stacking coefficients of the two points closest to L0 are taken as the undetermined stacking coefficients.

[0062] Step 3: Test the transformer core thickness under the principle of optimal clamping force distribution to select the optimal lamination coefficient from the undetermined lamination coefficients. The specific steps include the following:

[0063] Step 3.1: According to the relationship between the surface pressure and the discrete stacking coefficient, the surface pressure corresponding to each undetermined stacking coefficient is obtained respectively.

[0064] The relationship between the two is described in step 3.2, which will not be repeated here. Here, the discrete lamination coefficient curve is still taken as an example, and the surface pressure corresponding to each undetermined lamination coefficient is determined according to the curve.

[0065] Step 3.2: For each undetermined lamination coefficient, the total clamping force corresponding to its surface pressure is distributed to the screw corresponding to the transformer core according to the optimal clamping force distribution principle, wherein the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener.

[0066] Step 3.3: Under the preset conditions, fine-tune the torque of each screw and keep the surface pressure unchanged, compare the thickness distribution of the transformer core measured in real time with the core design thickness, retain the pending stacking coefficient that meets the thickness design requirements, and select the highest value (the value closest to 1) as the optimal stacking coefficient output.

[0067] The above method proposes a logical relationship between the clamping force and the stacking factor of the transformer core at this stage, that is, the clamping force is adjusted under the standard surface pressure to obtain the optimal clamping force distribution principle and the surface pressure corresponding to the optimal clamping force, so as to find the undetermined stacking factor close to the standard stacking factor, and the transformer core thickness test is carried out under the optimal clamping force distribution principle to screen out the optimal stacking factor that meets the thickness design requirements from the undetermined stacking factor, so that the designed transformer core can control the delivered stacking factor when leaving the factory, thereby reducing the factory customer complaints caused by poor stacking factor design, and also enhancing the stability of the core design, providing a basis for the theoretical calculation of the iron loss performance of the transformer core.

[0068] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is 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 in the protection scope of the present invention.

Claims

1. A coupling calculation method for transformer core clamping force and lamination coefficient, characterized in that: The method comprises: Under standard surface pressure, the clamping force acting on different positions of the transformer core is adjusted to obtain the optimal clamping force distribution principle and the corresponding surface pressure; Finding a pending lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle; Conducting a transformer core thickness test under the optimal clamping force distribution principle to screen out an optimal lamination coefficient from the pending lamination coefficients; The method of adjusting the clamping force acting on different positions of the transformer core under the standard surface pressure to obtain the optimal clamping force distribution principle and the corresponding surface pressure includes: The total clamping force corresponding to the standard surface pressure is distributed to the screws corresponding to the transformer core according to a preset ratio, wherein the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener; Under the preset conditions, the torque of each screw is adjusted and the standard surface pressure is kept unchanged until the clamping force distribution at different positions of the transformer core measured in real time is close to the calculated theoretical clamping force, and it is considered that the current torque of each screw matches the core design application scenario; The current torque of each screw is converted into a corresponding clamping force to obtain an optimal clamping force distribution principle, and the surface pressure corresponding to the current clamping force is calculated; Among them, searching for a pending lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle includes: The standard lamination coefficient calculated under the standard surface pressure is regarded as the lamination coefficient calculated under the surface pressure corresponding to the optimal clamping force distribution principle; According to the relationship between the surface pressure and the discrete stacking coefficient, the surface pressure corresponding to the optimal clamping force distribution principle is used to find a discrete stacking coefficient close to the standard stacking coefficient from the discrete stacking coefficients as the undetermined stacking coefficient; Wherein, the transformer core thickness test is performed under the optimal clamping force distribution principle to screen out the optimal lamination coefficient from the undetermined lamination coefficients, including: According to the relationship between the surface pressure and the discrete lamination coefficient, the surface pressure corresponding to each of the undetermined lamination coefficients is obtained respectively; For each of the undetermined lamination coefficients, the total clamping force corresponding to the surface pressure is distributed to the screw corresponding to the transformer core according to the optimal clamping force distribution principle; Under the preset conditions, the torque of each screw is finely adjusted and the surface pressure is kept constant, the thickness distribution of the transformer core measured in real time is compared with the core design thickness, the undetermined lamination coefficient that meets the thickness design requirements is retained, and the highest value is selected as the optimal lamination coefficient output; The preset condition is to change the thickness uniformity of the laminations of the transformer core.

2. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1 is characterized in that: Calculation of theoretical clamping force includes: Under the permissible environment of core design, the theoretical clamping force is calculated based on the actually selected screw-related parameters and the actually applied torque; wherein the screw-related parameters include: the pitch of the screw or bolt thread, the average friction coefficient between the thread and the head support, the thread median diameter of the screw or bolt thread, and the effective diameter of the friction torque in the screw head bracket or the nut bracket.

3. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1 is characterized in that: The method further comprises: The lamination coefficient of the transformer core is calculated in the horizontal state and the vertical state, so as to obtain the relationship between the surface pressure and the discrete lamination coefficient, which is described as follows: as the surface pressure increases, the lamination coefficient first increases to a maximum value and then decreases to a minimum value, and the maximum value and the minimum value fluctuate in the range of [0,1], and the lamination coefficient is a discrete value, and the surface pressure is a continuous value.

4. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1 is characterized in that: Calculating the standard lamination factor includes, under the standard surface pressure: Calculation of coating thickness of a single steel sheet on a transformer core h 1. Based on L 0= a ( h 2- h 1) / H Calculate and obtain the standard lamination coefficient; in, a is the number of core steel laminations, h 2 is the thickness of a single steel sheet, H The total thickness of all steel sheets involved in lamination is pressed down to the standard surface.

5. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 4 is characterized in that: Calculate the coating thickness of a single steel sheet in the transformer core, including: According to the density, mass and thickness of a single steel sheet, the coating thickness of the steel sheet can be inferred using the density formula.

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