Method for determining process coefficient of three-dimensional wound core

Abstract

The invention relates to a method for determining a process coefficient of a three-dimensional wound core, which is used for establishing quantitative characterization of the process coefficient of the iron core based on the influence of an iron core filling coefficient on iron loss and the influence of each production process on the iron loss. The iron core filling coefficient is determined by taking the iron core stage number and the iron core column equivalent sheet width as input data, and the iron loss influence factors in each production process comprise the influence of shear stress in the cutting process on the iron loss, the influence of tensile stress in the winding process on the iron loss and the influence of stress removal in the annealing process on the iron loss. The influence of the iron loss is determined by iron loss test curve fitting under each stress condition. Therefore, on one hand, the influence of each process on the iron loss in the production process can be truly and effectively reflected in real time, and on the other hand, the real and reliable data of the process section is provided for the subsequent iron loss analysis of the user side, so that the accurate analysis of the user side is facilitated, and the determination of the filling coefficient gives consideration to the determination of the production efficiency; and cost reduction is considered in parameter setting.

Description

Technical Field

[0001] The invention belongs to the field of transformer core production and manufacturing, and in particular relates to a method for determining a process coefficient of a three-dimensional wound core. Background Art

[0002] Transformers are electric energy transmission equipment manufactured based on the principle of electromagnetic induction. The iron core, as the core component of the transformer, is known as the "heart of the transformer", and oriented silicon steel is the constituent material of the iron core. Heat-resistant oriented silicon steel is the main material for three-dimensional wound cores.

[0003] The no-load performance of a transformer is one of the most important performances of a transformer. In the traditional calculation of no-load loss of a transformer, the influences of the above processes are all attributed to a coefficient K, which reflects the change in the unit loss of silicon steel sheets caused by the core structure or processing factors, called the core process coefficient. The specific formula is as follows:

[0004] P0=K×G tx ×P tx (W)

[0005] P0: Transformer no-load loss (W)

[0006] K: Core process coefficient

[0007] P tx :Unit iron loss (W / Kg)

[0008] G tx :Core weight(Kg)

[0009] In actual operation applications, K mentioned above is usually determined based on experience and is a certain value. However, the situation in the silicon steel production process is not always static. Specifically, in the production process of the core of the three-dimensional wound core transformer, there will be influencing factors in multiple processes, which makes the core process coefficient actually fluctuate. How to establish a characterization of the core process coefficient based on the actual situation of the actual process, so that the calculation of iron loss is more accurate, and provide a more accurate basis for transformer manufacturers to analyze the iron loss during the actual operation of the subsequent motor and various actual related analyses; making the corresponding analysis more accurate and able to point to the real problem has become a problem that needs to be further solved.

[0010] The invention application with application number: CN201610968298.4 discloses "a control model for a transformer core process coefficient". The transformer core production process coefficient K is decomposed into 5 sub-coefficients according to each process: stacking influence sub-coefficient K1, longitudinal shear influence sub-coefficient K2, transverse shear influence sub-coefficient K3, core structure influence sub-coefficient K4 and burr influence sub-coefficient K5; the control model of the core process coefficient K is as follows: K = (1 + K5) × (1 + K1 + K2 + K3 + K4); the core adopts oriented silicon steel.

[0011] The invention application with application number: CN201610231782.9 discloses "a transformer core section design method based on particle swarm optimization". First, the core number is determined according to the corresponding relationship between the transformer core diameter and the core number, and pre-processing is performed for the subsequent optimization of the stack thickness of each level. Then, the particle swarm optimization algorithm is applied to optimize and solve the stack thickness of each level, and then the final optimized design scheme is obtained.

[0012] The invention application with application number: CN202110589061.6 discloses "a method for evaluating the quality of an ultra-thin silicon steel core for a DC converter valve saturated reactor", comprising the following steps: S1, appearance evaluation; S2, stacking coefficient evaluation; S3, magnetic property evaluation; S4, noise evaluation; S5, environmental temperature change tolerance evaluation and S6, long-term operation performance evaluation. The present invention takes into account the DC converter valve saturated reactor's requirements for the appearance, stacking coefficient, magnetic property, noise and long-term operation of the ultra-thin silicon steel core, and realizes the performance evaluation of the appearance of the ultra-thin silicon steel core, the evaluation of the basic parameters of the core, the electromagnetic performance evaluation, the evaluation of the tolerance to environmental temperature changes and the long-term electrothermal operation characteristics evaluation, which provides a guarantee for the reliable operation of the ultra-thin silicon steel core for the DC converter valve saturated reactor.

[0013] The invention application with application number: CN201410038029.9 discloses "a method for quality judgment of stator core using noise", which is used to check the assembly quality of stator core and find out whether there are problems such as loose core compression, looseness, local cavity, etc. During the magnetization test of stator core, the noise sound pressure level, 1 / 3 octave spectrum, and local high point noise are tested; the arithmetic mean of the noise sound pressure level is taken, and the difference between the cold state and the hot state is calculated; the 1 / 3 octave of noise in the cold state and the hot state is plotted on the same spectrum diagram, and the difference of the spectrum is compared; the difference between local noises is compared to determine the maximum local noise value; the difference of the noise sound pressure level of the stator core in the cold state and the hot state is not more than 5dB, there is no abnormal difference in the 1 / 3 octave spectrum diagram of the noise in the cold state and the hot state, and the maximum local noise level difference is not more than 3dB, which is used as the basis for judging the quality of the stator core by noise.

[0014] However, the patent application does not provide a more accurate basis for the subsequent analysis of iron loss during actual operation of the motor and various practical related analyses, which makes the corresponding analysis inaccurate and difficult to solve practical problems. Summary of the invention

[0015] In order to solve the above problems, the present invention provides a method for determining the process coefficient of a three-dimensional wound core, and the technical solution thereof is as follows:

[0016] A method for determining a process coefficient of a three-dimensional wound core, characterized in that:

[0017] Based on the influence of core filling factor on iron loss and the influence of stress in each production process on iron loss, a quantitative characterization of core process coefficient is established.

[0018] The core filling factor is determined by taking the core number and the equivalent width of the core column as input data. The factors affecting the iron loss by stress in each production process include:

[0019] The influence of shear stress on iron loss during the cutting process, and

[0020] Effect of stress removal during annealing on iron loss,

[0021] The influence of stress on iron loss in each production process is determined by fitting the iron loss test curve under various stress conditions.

[0022] According to the method for determining the process coefficient of a three-dimensional wound core of the present invention, it is characterized in that:

[0023] Parameter optimization is performed with the goal of maximizing the core cross-sectional area and maximizing production efficiency.

[0024] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0025] The core process coefficient is determined according to the following formula:

[0026] K=1+(K1+K2+K3-K4)100, where

[0027] K: core process coefficient;

[0028] K1: Parameters based on the influence of core filling factor on iron loss (%);

[0029] K2: Parameters based on the influence of shear stress on iron loss during the cutting process (%);

[0030] K3: Parameters based on the influence of tensile stress on iron loss during the winding process (%);

[0031] K4: Parameter (%) based on the effect of stress removal in the annealing process on iron loss.

[0032] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0033] The influence of core filling factor on iron loss is as follows:

[0034] K1=(1.4N 2 -44N+1650) / 100-2.8Ln(d),

[0035] in,

[0036] K1: Parameters based on the influence of core filling factor on iron loss (%);

[0037] N: core series;

[0038] d: Equivalent width of the core column, unit: mm.

[0039] Among them, N: 2~16; d: 30~300mm.

[0040] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0041] N=5~10, d=50~200mm.

[0042] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0043] Based on different sheet thicknesses and different deviation angles between the cutting (sheet) and the rolling direction, the curve fitting of the iron loss test is performed to determine the parameters affecting the iron loss based on the shear stress in the cutting process;

[0044] That is, the oriented silicon steel samples are sheared at different angles away from the rolling direction, and then the samples are taken for loss testing to find out the relationship between the loss of materials of different thicknesses under different shear angles.

[0045] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0046] The parameters of the influence of shear stress on iron loss in the cutting process are determined according to the following formula:

[0047] K2=15-50×h+0.5×a,

[0048] in,

[0049] K2: Parameters based on the influence of shear stress on iron loss during the cutting process (%);

[0050] h: core thickness, unit: mm;

[0051] a: Curve cutting angle, unit: °.

[0052] Among them, h: 0.18~0.3mm; a<5°.

[0053] According to the present invention, h determines the thickness according to the material selected by the user, and the curved cutting angle of a is preferably as small as possible.

[0054] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0055] Based on the curve fitting of the iron loss test in the holding section of the annealing process, the parameters affecting the iron loss due to stress removal in the annealing process are determined.

[0056] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0057] Among them, K3 range: 0~50(%).

[0058] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0059] In the case of large capacity and large product winding radius, the value range is 5% to 20%;

[0060] When the winding radius of small capacity products is small, the value range is 20% to 50%.

[0061] The value of K3 is mainly determined by the process parameters of the core winding process, and is mainly related to the product winding radius and tension.

[0062] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0063] The parameters based on the influence of stress removal in the annealing process on the iron loss are determined according to the following formula:

[0064] K4=(T×t) / (4000×K3)

[0065] K4: Parameters affecting iron loss based on stress removal in the annealing process (%);

[0066] T: annealing temperature, unit: °C;

[0067] t: maximum temperature annealing time, unit: h;

[0068] K3: 0~50(%).

[0069] Among them, T=780~830; t=1.5-2.

[0070] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0071] T=800~820, t=2.

[0072] According to a method for determining a process coefficient of a three-dimensional wound core of the present invention, a quantitative characterization of the iron loss process coefficient is established from two aspects: the influence of the core filling coefficient on the iron loss and the influence of the stress generated in the process on the iron loss. On the one hand, the influence of each process in the production process on the iron loss can be truly and effectively reflected in real time. On the other hand, true and reliable data of the process segment is provided for subsequent user-side iron loss analysis, which facilitates accurate analysis on the user side. The filling coefficient is determined while taking into account the determination of production efficiency, and cost reduction is taken into account in the parameter setting. The overall technical solution achieves the effects of improving product performance, reducing costs, and lean production. DETAILED DESCRIPTION

[0073] Next, a method for determining a process coefficient of a three-dimensional wound core of the present invention is further described in detail according to a specific implementation manner.

[0074] A method for determining the process coefficient of a three-dimensional wound core.

[0075] Based on the influence of core filling factor on iron loss and the influence of stress in each production process on iron loss, a quantitative representation of core process coefficient is established.

[0076] in,

[0077] The core filling factor is a filling factor that takes production efficiency into consideration. Based on this, the core number and the equivalent sheet width of the core column are used as input data, and parameter optimization is performed with the maximum core cross-sectional area and the maximum production efficiency as the goals, and a quantitative representation of the core process coefficient based on the core filling factor is established.

[0078] in,

[0079] Based on the influence of stress on iron loss in each production process, it includes: the influence of shear stress on iron loss in the cutting process, the influence of tensile stress on iron loss in the winding process, and the influence of stress removal on iron loss in the annealing process.

[0080] in,

[0081] A quantitative characterization of the core process coefficient is established based on the influence of stress on iron loss in each production process, which is determined by fitting the iron loss test curve under various stress conditions.

[0082] in,

[0083] The core process coefficient is determined according to the following formula:

[0084] K=1+(K1+K2+K3-K4)100,

[0085] K: core process coefficient;

[0086] K1: Parameter based on the influence of core filling factor on iron loss;

[0087] K2: Parameter based on the influence of shear stress on iron loss during the cutting process;

[0088] K3: Parameter based on the influence of tensile stress on iron loss during the winding process;

[0089] K4: Parameter based on the effect of stress removal during the annealing process on iron loss.

[0090] in,

[0091] The influence of the core filling factor on the iron loss taking into account production efficiency is as follows:

[0092] K1=(1.4N 2 -44N+1650) / 100-2.8Ln(d),

[0093] K1: Parameter based on the influence of core filling factor on iron loss;

[0094] N: core series;

[0095] d: Equivalent width of the core column, unit: mm.

[0096] in,

[0097] Based on the curve fitting of the iron loss test for different sheet thicknesses and different deviation angles between the cutting and rolling directions, the influencing parameters of the shear stress in the cutting process on the iron loss were determined.

[0098] in,

[0099] Based on the curve fitting of the iron loss test with different curvature radii and different winding tensions during winding, the influencing parameters of the tensile stress in the winding process on the iron loss are determined.

[0100] in,

[0101] Based on the curve fitting of the iron loss test in the holding section of the annealing process, the parameters affecting the iron loss due to stress removal in the annealing process are determined.

[0102] in,

[0103] The parameters of the influence of shear stress on iron loss in the cutting process are determined according to the following formula:

[0104] K2=15-50×h+0.5×a,

[0105] K2: Parameter based on the influence of shear stress on iron loss during the cutting process;

[0106] h: core thickness, unit: mm;

[0107] a: Curve cutting angle, unit: °.

[0108] in,

[0109] The parameters based on the influence of stress removal in the annealing process on the iron loss are determined according to the following formula:

[0110] K4=(T×t) / (4000×K3),

[0111] K4: Parameters based on the effect of stress removal in the annealing process on iron loss;

[0112] T: annealing temperature, unit: °C;

[0113] t: maximum temperature annealing time, unit: h;

[0114] K3: Parameter based on the influence of tensile stress on iron loss during the winding process, K3 range: 0~50(%).

[0115] The value of K3) is mainly determined by the process parameters of the core winding process, and is mainly related to the product winding radius and tension.

[0116] A method for determining a process coefficient of a three-dimensional wound core according to the present invention is characterized in that:

[0117] In the case of large capacity and large product winding radius, the value range is 5% to 20%;

[0118] When the winding radius of small capacity products is small, the value range is 20% to 50%.

[0119] Working principle and process

[0120] To facilitate understanding of the present technical solution, the mechanism of the present technical solution is explained below from the perspective of the production process.

[0121] The core sheet type influence module K1 described below is the influence parameter of the core filling factor on the iron loss described above; the curve cutting influence module K2 described below is the influence parameter of the shear stress in the cutting process on the iron loss described above; the winding process influence module K3 described below is the influence parameter of the tensile stress in the winding process on the iron loss described above; the annealing process influence module K4 described below is the influence parameter of the stress removal in the annealing process on the iron loss described above.

[0122] According to the design and production process of three-dimensional wound core, the process influence coefficient of the core is decomposed into four main modules according to each process. Each module accurately characterizes the impact of each process and structure on the performance of oriented silicon steel, and ultimately affects the performance parameters of the entire core.

[0123] K=1+(K1+K2+K3-K4) / 100

[0124] K1: Core lamination type influence module (coefficient, %);

[0125] K2: Curve cutting influence module (coefficient, %);

[0126] K3: Winding process influence module (coefficient, %);

[0127] K4: Annealing process influence module (coefficient, %);

[0128] Detailed analysis of each module

[0129] 1K1 core type impact module

[0130] The number of levels of three-dimensional wound core design and the size of each level have a great influence on the core loss. Increasing the number of core levels can increase the filling factor of the core and improve the core performance, but increasing the cross-sectional area of ​​the core will increase the types of cut pieces, increase the process difficulty, and reduce production efficiency. It is necessary to find the balance point between increased performance and reduced production efficiency in combination with the characteristics of the own process, and decide to increase or decrease the number of levels based on the balance point to maximize economic benefits. That is, a comprehensive optimization is established with the optimization of cross-sectional area and production efficiency as the goal, so as to determine K1; the calculation model of K1 is as follows:

[0131] K1=(1.4N 2 -44N+1650) / 100-2.8Ln(d)

[0132] Where, N: number of core stages; d: equivalent width of core column, mm.

[0133] 2K2 curve cutting influence module (%)

[0134] Three-dimensional rolled core will generate stress during the cutting process. The thickness of the core sheet is different, and the stress magnitude is different. The magnitude of the stress affects the degree of degradation of the oriented silicon steel performance. At the same time, the curve cutting will have a deviation angle from the rolling direction of the oriented silicon steel, which will also cause the performance of the oriented silicon steel to deteriorate. This is because the stress zone will produce extremely elongated boundaries along the tearing direction. The increase in the grain boundary density in the stress zone along the shear direction will lead to an increase in the iron loss in this area. At the same time, the sharpness of the shear will also significantly affect the size of the deformation area. K2 is determined by fitting the curve of the iron loss test at different shear deviation angles through the longitudinal shearing equipment for materials of different thicknesses.

[0135] K2=15-50h+0.5*a

[0136] Where, h: core sheet thickness, mm, a: curve cutting angle.

[0137] 3K3: Based on the tensile stress influence module in the winding process, K3 range: 0~50(%).

[0138] The value of K3 is mainly determined by the process parameters of the core winding process, and is mainly related to the product winding radius and tension.

[0139] Preferably,

[0140] In the case of large capacity and large product winding radius, the value range is 5% to 20%;

[0141] In the case of small capacity and small product winding radius, the value range is 20% to 50%.

[0142] 4K4 annealing process affects the module (%)

[0143] Annealing of three-dimensional wound core is a key link that affects the performance of the core. It can eliminate the residual stress of the core during shearing and winding, and reduce the influence of stress on the performance of oriented silicon steel. In terms of annealing process, the temperature and time must meet the requirements of the annealing curve. At the same time, the process after annealing and taking out of the furnace must be handled well, otherwise it will have a greater impact on the performance of the core. The calculation model of K4 is as follows. The model omits the influencing factors of the annealing heating stage and the annealing cooling stage, and focuses on the high insulation temperature and equivalent time actually reached in various parts of the core. By fitting the curve of the iron loss test of the insulation section of the annealing process, the influence parameter K4 on the iron loss based on the stress removal in the annealing process is determined.

[0144] K4=(T*t) / (4000*K3)

[0145] Where: T is the annealing temperature, °C; t is the maximum temperature annealing time, h is the value range of each module factor

[0146] In engineering applications, each module factor and its variable has a certain range of values. For the core of the three-phase distribution transformer with three-dimensional wound core, the combined range of values ​​is shown in the following table.

[0147] Process module Value range K1 N: 2~16; d: 30~300 K2 h:0.18~0.3;a<5 K3 0～50 K4 T:780~830; t:2

[0148] Example

[0149] Embodiment: The following table is the processing data and no-load loss test results of the core part of the S20-200KVA distribution transformer of a domestic three-dimensional wound core manufacturer in December 2021. Based on these data, the actual coefficient of the product can be calculated. According to the analytical model of the present invention, the model coefficient of each process can be calculated, and then the process coefficient model of the entire three-dimensional wound core can be accurately calculated.

[0150]

[0151] It can be seen from the above table that the overall performance parameter (K) of the entire core calculated according to the process model established in each process step is very close to the core process coefficient obtained from the test results, and the model calculation results are accurate.

[0152] Since the product of Comparative Example 1 has few winding stages, uneven winding tension control, and insufficient high-insulation equivalent annealing temperature, the process coefficients of K1\K3\K4 are high; the product of Comparative Example 2 has few winding stages and uneven winding tension control, so the performance of K1\K3 products is poor. The model of the present invention can accurately analyze the influence of the process on the product performance, improve the quality of different processes, and reduce the final process coefficient of the three-dimensional wound core. The embodiment is optimized by 5% compared with Comparative Example 1.

[0153] It can be seen from the above embodiments that the analysis model of this invention can analyze the influence of the quality of each process of the core on the overall performance of the core, accurately adjust the process parameters of the three-dimensional wound core manufacturing process, and help manufacturers reduce costs and increase efficiency.

Claims

1. A method for determining a process coefficient of a three-dimensional wound core, characterized in that: Based on the influence of core filling factor on iron loss and the influence of stress in each production process on iron loss, a quantitative characterization of core process coefficient is established. The core filling factor is determined by taking the core number and the equivalent width of the core column as input data. The factors affecting the iron loss caused by stress in each production process include: The influence of shear stress on iron loss during the cutting process, The effect of tensile stress on iron loss during the winding process, and Effect of stress removal during annealing on iron loss, The influence of stress on iron loss in each production process is determined by fitting the iron loss test curve under various stress conditions.

2. The method for determining the process coefficient of a three-dimensional wound core according to claim 1, characterized in that: The core process coefficient is determined according to the following formula: K=1+(K1+K2+K3-K4)100, in, K: core process coefficient; K1: Parameters based on the influence of core filling factor on iron loss (%); K2: Parameters based on the influence of shear stress on iron loss during the cutting process (%); K3: Parameters based on the influence of tensile stress on iron loss during the winding process (%); K4: Parameter (%) based on the effect of stress removal in the annealing process on iron loss.

3. The method for determining the process coefficient of a three-dimensional wound core according to claim 2, characterized in that: The influence of core filling factor on iron loss is as follows: K1=(1.4N 2 -44N+1650) / 100-2.8Ln(d), in, K1: Parameters based on the influence of core filling factor on iron loss (%); N: core series; d: Equivalent width of the core column, unit: mm. Among them, N: 2~16; d: 30~300mm.

4. The method for determining the process coefficient of a three-dimensional wound core according to claim 3, characterized in that: N: 5~10, d: 50~200mm.

5. The method for determining the process coefficient of a three-dimensional wound core according to claim 1, characterized in that: Based on different sheet thicknesses and different deviation angles between the cutting (sheet) and the rolling direction, the curve fitting of the iron loss test is performed to determine the parameters affecting the iron loss based on the shear stress in the cutting process; That is, the oriented silicon steel samples are sheared at different angles away from the rolling direction, and then the samples are taken for loss testing to find out the relationship between the loss of materials of different thicknesses under different shear angles.

6. The method for determining the process coefficient of a three-dimensional wound core according to claim 5, characterized in that: The parameters of the influence of shear stress on iron loss in the cutting process are determined according to the following formula: K2=15-50×h+0.5×a, in, K2: Parameters based on the influence of shear stress on iron loss during the cutting process (%); h: core thickness, unit: mm; a: Curve cutting angle, unit: °. Among them, h: 0.18~0.3mm; a<5°.

7. The method for determining the process coefficient of a three-dimensional wound core according to claim 2, characterized in that: Based on the curve fitting of the iron loss test in the holding section of the annealing process, the parameters affecting the iron loss due to stress removal in the annealing process are determined.

8. The method for determining the process coefficient of a three-dimensional wound core according to claim 1, characterized in that: K3：0～50(％)。 9. The method for determining the process coefficient of a three-dimensional wound core according to claim 8, characterized in that: In the case of large capacity and large product winding radius, the value range is 5% to 20%; When the winding radius of small capacity products is small, the value range is 20% to 50%.

10. The method for determining the process coefficient of a three-dimensional wound core according to claim 8, characterized in that: The parameters based on the influence of stress removal in the annealing process on the iron loss are determined according to the following formula: K4=(T×t) / (4000×k3) in, K4: Parameters affecting iron loss based on stress removal in the annealing process (%); T: annealing temperature, unit: °C; t: maximum temperature annealing time, unit: h; K3: Value range: 0~50(%). Among them, T=780-830; t=1.5-2.

11. The method for determining the process coefficient of a three-dimensional wound core according to claim 8, characterized in that: T=800~820, t=2.

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