CN117150750A - Coupling calculation method for clamping force and lamination coefficient of transformer core - Google Patents

Abstract

The invention discloses a coupling calculation method of transformer core clamping force and lamination coefficient, which relates to the technical field of transformer design. The method includes: regulating the clamping force acting on different positions of the transformer core under standard surface pressure to obtain the optimal The clamping force distribution principle and the corresponding surface pressure; find the undetermined lamination coefficient close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle; conduct the transformer core thickness test under the optimal clamping force distribution principle, The optimal lamination coefficient is obtained by screening the undetermined lamination coefficients. This method proposes a logical relationship between the clamping force and the lamination coefficient of the transformer core at the current stage, that is, by regulating the clamping force, the optimal lamination coefficient that meets the design requirements is output, and the errors caused by the influence of the lamination coefficient are reduced. factory customer complaints, which also enhances the stability of the core design.

Description

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

Technical field

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

Background technique

The transformer core is made of stacked silicon steel sheets, and the manufacturing process of silicon steel sheets is relatively complex. The uneven thickness of silicon steel sheets caused by the coating process is one of the main reasons for the air gap left between the sheets after stacking the silicon steel sheets. . In addition to the coating process, another main reason for the uneven size of the air gaps between the silicon steel sheets is the clamping force provided by the fasteners used to fix the stacked silicon steel sheets. However, since most manufacturers focus on production efficiency, they often neglect to adjust the clamping force of the clamps, resulting in weak air gap control, which affects the lamination coefficient and effective cross-sectional area of the transformer core design, resulting in a reduction in the magnetic properties of the transformer core, affecting Transformer core production quality.

At present, the existing transformer core design does not take into account the impact of clamping force on the lamination coefficient, that is, there is no standardized calculation logic for manufacturers to use, resulting in a large error in the lamination coefficient of the transformer core delivered at the factory. The magnetic performance of the iron core exceeds the standard, and the number of customer complaints caused by the factory remains high.

Contents of the invention

In view of the above problems and technical needs, the inventor proposed a coupling calculation method for the clamping force of the transformer core and the lamination coefficient, and proposed the logical relationship between the clamping force and the lamination coefficient of the transformer core at this stage, that is, through Adjust the clamping force to output the optimal lamination coefficient that meets the design requirements. The technical solution of the present invention is as follows:

A coupling calculation method for transformer core clamping force and lamination coefficient, including the following steps:

Adjust the clamping force acting on different positions of the transformer core under standard surface pressure to obtain the optimal clamping force distribution principle and corresponding surface pressure;

Find the undetermined lamination coefficient that is close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle;

Conduct a transformer core thickness test under the optimal clamping force distribution principle to screen out the optimal lamination coefficient from the undetermined lamination coefficients.

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

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, and the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener;

Adjust the torque of each screw under preset conditions and keep the standard surface pressure unchanged until the real-time measured clamping force distribution at different positions of the transformer core is close to the calculated theoretical clamping force, then it is considered that the current torque of each screw matches the core Design application scenarios;

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;

Among them, the preset condition is to change the uniformity of the lamination thickness of the transformer core.

Its further technical solution is to calculate the theoretical clamping force including:

Under the allowable environment of the iron core design, the theoretical clamping force is calculated based on the actual selected screw-related parameters and the actual applied torque; among them, the screw-related parameters include: the pitch of the screw or bolt thread, the average friction coefficient of the thread and the head support, the screw or the thread pitch diameter of the bolt thread, and the effective diameter of the friction torque in the screw head bracket or nut bracket.

Its further technical solution is to find an undetermined lamination coefficient close to the standard lamination coefficient based on the surface pressure corresponding to the optimal clamping force distribution principle, including:

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 surface pressure and discrete lamination coefficient, the surface pressure corresponding to the optimal clamping force distribution principle is used to find the discrete lamination coefficient that is close to the standard lamination coefficient from the discrete lamination coefficient as the undetermined lamination coefficient.

Its further technical solution is to test the thickness of the transformer core under the principle of optimal clamping force distribution 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 undetermined lamination coefficient is obtained;

For each undetermined lamination coefficient, the total clamping force corresponding to its surface pressure is allocated to the screw corresponding to the transformer core according to the optimal clamping force distribution principle. The clamping force distribution is achieved by adjusting the torque of each screw in the fastener. ;

Fine-tune the torque of each screw under preset conditions and keep the surface pressure unchanged. Compare the real-time measured thickness distribution of the transformer core with the core design thickness, retain the undetermined lamination coefficient that meets the thickness design requirements, and select the highest value as the best value. Best lamination coefficient output;

Among them, the preset condition is to change the uniformity of the lamination thickness of the transformer core.

Its further technical solution is that the method also includes:

Calculate the lamination coefficient of the transformer core in the horizontal and vertical states to obtain the relationship between surface pressure and discrete lamination coefficient, which is described as: as the surface pressure increases, the lamination coefficient first increases to the maximum value , and then decrease to the minimum value, 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.

Its further technical solution is to calculate the standard lamination coefficient including, under standard surface pressure:

Calculate the coating thickness h ₁ of a single steel sheet in the transformer core, and calculate the standard lamination coefficient based on L ₀ =a(h ₂ -h ₁ )/H;

Among them, a is the number of laminated core steel sheets, h ₂ is the thickness of a single steel sheet, and H is the total thickness of all steel sheets participating in the lamination under standard surface pressure.

Its further technical solution is to 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 is deduced based on the density formula.

The beneficial technical effects of the present invention are:

This method proposes a logical relationship between the clamping force and the lamination coefficient of the transformer core at this stage, that is, adjusting the clamping force under the standard surface pressure to obtain the optimal clamping force distribution principle and the surface corresponding to the optimal clamping force. Pressure, in order to find the undetermined lamination coefficient that is close to the standard lamination coefficient, and conduct the transformer core thickness test under the optimal clamping force distribution principle to screen out the optimal lamination coefficient that meets the thickness design requirements from the undetermined lamination coefficients , so that the designed transformer core can control the delivered lamination coefficient when leaving the factory, thereby reducing factory customer complaints caused by poor design of the lamination coefficient, and also enhancing the stability of the core design, providing a theoretical basis for the iron loss performance of the transformer core Provide basis for calculation.

Description of the drawings

Figure 1 is a flow chart of the coupling calculation method of transformer core clamping force and lamination coefficient provided by this application.

Figure 2 is a graph of the relationship between surface pressure and discrete lamination coefficient provided by this application.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

Please refer to Figure 1. This embodiment provides a coupling calculation method for the transformer core clamping force and lamination coefficient, which includes the following steps:

Step 1: Adjust the clamping force acting on different positions of the transformer core under standard surface pressure to obtain the optimal clamping force distribution principle and corresponding surface pressure.

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. Torque is applied to each screw in the fastener, so that the fastener provides the yoke with The clamping force acts on the corresponding position of the transformer core to obtain stable surface pressure. Since when designing the transformer core, the four parts of the silicon steel sheet will be considered: plate length, plate width, plate density and plate thickness. Among them, the plate length and plate width are designed to ensure the magnetic density of the core, and their inherent errors are unavoidable in actual production. And optimization, under the premise that the density of the plate is relatively stable, the thickness of the plate will be affected by the surface pressure, which will cause 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.

Specifically, it includes the following sub-steps:

Step 1.1: Distribute the total clamping force corresponding to the standard surface pressure to the screw corresponding to the transformer core according to the preset proportion.

Among them, the total clamping force corresponding to the standard surface pressure can be obtained by converting the relationship between the clamping force, the relative area of the iron core and the clamp, and the surface pressure. The industry stipulates that the standard surface pressure is usually 0.15Mpa.

Among them, the distribution of clamping force is achieved by adjusting the torque of each screw in the fastener.

Optional, the preset ratio is generally 1:2:1, distributed according to side screw: through-core screw: side screw.

Step 1.2: Adjust the torque of each screw under preset conditions and keep the standard surface pressure unchanged, and 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 believed that the current 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 also allowed as long as it is within the specified error range. It should be understood that similar meanings appearing in the following steps are the same as here.

It should be noted that the clamping force of the yoke can be adjusted at most 0.1-1.2Mpa surface pressure.

<1>Methods for calculating theoretical clamping force include:

Under the allowable environment of the iron core design, calculate the theoretical clamping force F _M (unit N) based on the actual selected screw related parameters and the actual applied torque M _A (unit Nm). Among them, the screw-related parameters include: the pitch P (unit mm) of the screw or bolt thread, the average friction coefficient μ _GES of the thread and head support, the thread pitch diameter D ₂ (unit mm) of the screw or bolt thread, and the screw head bracket Or the effective diameter of the friction torque in the nut bracket D _KM (unit: mm). Based on the above parameters, the calculation formula given in this embodiment is:

Among them, D _KM = (D _B + D _M )/2, D _B is the hole diameter of the screw or bolt thread, and D _M is the diameter of the nut bracket.

<2>The preset condition set in this application is to change the uniformity of the laminate thickness of the transformer core.

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

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 (i.e., the current torque).

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

Step 2: Find the undetermined lamination coefficient that is close to the standard lamination coefficient based on the surface pressure corresponding to the optimal clamping force distribution principle. Specifically, it includes the following sub-steps:

Step 2.1: 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.

The method of calculating the standard lamination coefficient includes: calculating the coating thickness h ₁ of a single steel sheet of the transformer core under standard surface pressure, and calculating the standard lamination coefficient based on L ₀ =a(h ₂ -h ₁ )/H.

Among them, a is the number of laminated core steel sheets, h ₂ is the thickness of a single steel sheet, and H is the total thickness of all steel sheets participating in the lamination under standard surface pressure.

Among them, the method of calculating the coating thickness h ₁ includes: based on the density, mass and thickness of a single steel piece, and deducing the coating thickness of the steel piece based on the density formula. Specifically, the density and mass of a single film-contained steel sheet are calculated through the density formula to obtain the volume of the film-contained steel sheet. Since the length and width information of the steel sheet (plate) has been determined in step 1, the film-contained steel sheet can be calculated. The coating thickness of the steel sheet can be obtained by subtracting the thickness of the sheet from the thickness of the sheet.

Step 2.2: According to the relationship between surface pressure and discrete lamination coefficient, use the surface pressure corresponding to the optimal clamping force distribution principle to find the discrete lamination coefficient from the discrete lamination coefficient that is close to the standard lamination coefficient L ₀ as The undetermined lamination coefficient, that is, the discrete lamination coefficient within the specified range of L ₀ ±α, can be regarded as a discrete lamination coefficient close to L ₀ .

In this embodiment, it also includes: calculating the lamination coefficient of the transformer core in the horizontal state and the vertical state, thereby obtaining the relationship between the surface pressure and the discrete lamination coefficient, which is described as: as the surface pressure increases, The lamination coefficient first increases to the maximum value and then decreases to the minimum value. The lamination coefficient is a discrete value and the surface pressure is a continuous value. The maximum and minimum values fluctuate in the range [0,1]. This embodiment is preferred. The maximum value is 1 and the minimum value is 0, then the discrete stacking coefficient changes in the range of [0,1]. Specifically, the core of the transformer is in a horizontal state when stacking is completed. At this time, there is almost no surface pressure. When the core is erected on the flipping table, the core is in a vertical state. During the flipping process, high surface pressure is required to maintain the core's stable uprightness. Afterwards, it needs to be Regulate the surface pressure and restore it to the standard surface pressure state; record the relationship between the surface pressure and the corresponding lamination coefficient during this process, thereby establishing a discrete lamination coefficient curve or a discrete lamination coefficient table. This application exemplifies The discrete lamination coefficient curve is shown in Figure 2.

Taking the discrete lamination 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 L ₀ corresponding to the surface pressure will inevitably appear near a certain value of the curve, whichever is closest to L ₀ The two-point discrete lamination coefficient is used as the undetermined lamination coefficient.

Step 3: Conduct a transformer core thickness test under the optimal clamping force distribution principle to screen out the best lamination coefficient from the undetermined lamination coefficients. Specifically, it includes the following sub-steps:

Step 3.1: According to the relationship between the surface pressure and the discrete lamination coefficient, obtain the surface pressure corresponding to each undetermined lamination coefficient.

The relationship between the two is described in step 3.2 and will not be repeated here. Here we still take the discrete lamination coefficient curve as an example, and determine the surface pressure corresponding to each undetermined lamination coefficient based on the curve.

Step 3.2: For each undetermined lamination coefficient, the total clamping force corresponding to its surface pressure is allocated to the screw corresponding to the transformer core according to the optimal clamping force distribution principle. The clamping force is distributed by adjusting each of the fasteners. Screw torque is achieved.

Step 3.3: Fine-tune the torque of each screw under preset conditions and keep the surface pressure constant. Compare the real-time measured thickness distribution of the transformer core with the core design thickness, retain the undetermined lamination coefficient that meets the thickness design requirements, and select the highest value (the value closest to 1) is output as the optimal stacking coefficient.

The above method puts forward the logical relationship between the clamping force and the lamination coefficient of the transformer core at the current stage, that is, adjusting the clamping force under the standard surface pressure to obtain the optimal clamping force distribution principle and the surface corresponding to the optimal clamping force. Pressure, in order to find the undetermined lamination coefficient that is close to the standard lamination coefficient, and conduct the transformer core thickness test under the optimal clamping force distribution principle to screen out the optimal lamination coefficient that meets the thickness design requirements from the undetermined lamination coefficients , so that the designed transformer core can control the delivered lamination coefficient when leaving the factory, thereby reducing factory customer complaints caused by poor design of the lamination coefficient, and also enhancing the stability of the core design, providing a theoretical basis for the iron loss performance of the transformer core Provide basis for calculation.

The above are only 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 thought of 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 (8)

1. A coupling calculation method for transformer core clamping force and lamination coefficient, characterized in that the method includes: Adjust the clamping force acting on different positions of the transformer core under standard surface pressure to obtain the optimal clamping force distribution principle and corresponding surface pressure; Find the undetermined lamination coefficient that is close to the standard lamination coefficient according to the surface pressure corresponding to the optimal clamping force distribution principle; Conduct a transformer core thickness test under the optimal clamping force distribution principle to screen out the optimal lamination coefficient from the undetermined lamination coefficients. 2. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1, characterized in that, the clamping force acting on different positions of the transformer core is regulated under standard surface pressure to obtain the optimal clamping force. Tightening force distribution principles and corresponding surface pressure include: 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, and the distribution of the clamping force is achieved by adjusting the torque of each screw in the fastener; Adjust the torque of each screw under preset conditions and keep the standard surface pressure unchanged until the real-time measured clamping force distribution at different positions of the transformer core is close to the calculated theoretical clamping force, then the current torque of each screw is considered Match core design application scenarios; 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; Wherein, the preset condition is to change the uniformity of laminate thickness of the transformer core. 3. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 2, characterized in that calculating the theoretical clamping force includes: Under the allowable environment of the iron core design, the theoretical clamping force is calculated based on the actual selected screw-related parameters and the actual applied torque; among them, the screw-related parameters include: the pitch of the screw or bolt thread, the average friction coefficient of the thread and the head support, the screw or the thread pitch diameter of the bolt thread, and the effective diameter of the friction torque in the screw head bracket or nut bracket. 4. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1, characterized in that, according to the surface pressure corresponding to the optimal clamping force distribution principle, the undetermined lamination coefficient that is close to the standard lamination coefficient is found. slice coefficients, including: 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 lamination coefficient, the surface pressure corresponding to the optimal clamping force distribution principle is used to find the discrete lamination coefficient from the discrete lamination coefficient that is close to the standard lamination coefficient. as the undetermined lamination coefficient. 5. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 1, characterized in that the transformer core thickness test is carried out under the optimal clamping force distribution principle to determine the thickness of the transformer core from the to-be-determined stack. The optimal lamination coefficient is obtained by screening among the wafer 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; For each of the undetermined lamination coefficients, the total clamping force corresponding to its surface pressure is allocated to the screw corresponding to the transformer core according to the optimal clamping force distribution principle, where the clamping force is distributed by adjusting the fasteners. The torque of each screw is realized; Fine-tune the torque of each screw under preset conditions and keep the surface pressure unchanged, compare the real-time measured thickness distribution of the transformer core with the core design thickness, retain the undetermined lamination coefficient that meets the thickness design requirements, and select the highest value Output as the optimal stacking coefficient; Wherein, the preset condition is to change the uniformity of laminate thickness of the transformer core. 6. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 4 or 5, characterized in that the method further includes: The lamination coefficient of the transformer core is calculated in the horizontal state and the vertical state, thereby obtaining the relationship between the surface pressure and the discrete lamination coefficient, which is described as: as the surface pressure increases, the lamination coefficient first increases It increases to the maximum value and then decreases to the minimum value. 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. 7. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 4, characterized in that, calculating the standard lamination coefficient includes, under the standard surface pressure: Calculate the coating thickness h ₁ of a single steel sheet of the transformer core, and calculate the standard lamination coefficient based on L ₀ =a(h ₂ -h ₁ )/H; Among them, a is the number of laminated core steel sheets, h ₂ is the thickness of a single steel sheet, and H is the total thickness of all steel sheets participating in the lamination under standard surface pressure. 8. The coupling calculation method of transformer core clamping force and lamination coefficient according to claim 7, characterized in that calculating the coating thickness of a single steel sheet of the transformer core includes: According to the density, mass and thickness of a single steel sheet, the coating thickness of the steel sheet is deduced based on the density formula.