A communication base station high-power relay welding force calculation method considering contact surface topography

Abstract

The application discloses a communication base station high-power relay welding force calculation method considering contact surface topography, and belongs to the technical field of electric contact and electric appliance switch reliability analysis. In order to realize accurate calculation of the welding force of the communication base station high-power relay, a virtual assembly digital model of the matched contact is established according to the actual assembly relationship; the interference area between the virtual assembly digital models under a preset penetration depth is calculated and divided into a plurality of independent sub-interference areas; an equivalent contact body model of the static contact and the moving contact is constructed according to the local interference amount and the interference area of the sub-interference area; the corresponding contact resistance is calculated according to the real contact area, and the current value flowing through each contact area is determined; a thermal balance equation between the joule heat power and the material temperature rise is established, and the center maximum temperature of each contact area is calculated; the temperature field distribution of each contact area and the vicinity thereof is calculated, and the melting area range thereof is determined; the melting area and the welding force of each melting area are calculated, and the total welding force prediction value of the high-power relay is obtained.

Description

Technical Field

[0001] This invention belongs to the field of reliability analysis technology of electrical contact and electrical switch, and specifically relates to a method for calculating the welding force of high-power relays in communication base stations that takes into account the surface morphology of the contacts. Background Technology

[0002] With the increasing capacity of communication base station equipment and the growing complexity of power supply system operating conditions, the switching and protection requirements of communication base station power circuits under conditions such as high current flow and short circuit faults are becoming increasingly prominent, placing higher demands on the current-carrying capacity and breaking reliability of high-power switching elements. High-power relays, as crucial switching devices in the power switching and circuit control links of communication base stations, not only need to stably carry operating current for extended periods when their contacts are closed, but may also withstand transient short-circuit currents during system faults. When a short-circuit fault occurs, the current density in the micro-contact area of ​​the contacts increases significantly, causing a rapid rise in the temperature of the contact material due to the resulting localized thermal effect, leading to melting, resolidification, and welding. Welding will cause the contacts to stick together, preventing normal breaking and severely impacting the breaking function of high-power relays and the safe and stable operation of communication base station equipment. Therefore, establishing a modeling and evaluation method for the welding force of high-power relays under short-circuit current conditions is of great significance for the structural design, material selection, and reliability assessment of high-power relays.

[0003] Currently, the detection of welding force is mainly achieved through experimental testing. Patent CN103308387B designs a welding force testing device based on the lever principle. It utilizes a weight applied to one end of the lever to generate contact pressure. After energizing the contacts, the weight is gradually increased (or decreased) at the other end of the lever until the contacts are forcibly pulled apart. This is primarily used for static welding force testing. Patent CN202648850U designs a vertical breaking test system driven by a motor or cylinder. The motor controls the closing and breaking of the contacts, and the welding force is measured by a piezoelectric force sensor on the moving contact side. Patent CN110274827B constructs an experimental system that can automatically control contact closure, trigger current output, and force and displacement signal acquisition. Patent CN104124106A designs a simulated relay device with adjustable mechanical parameters (such as overtravel, contact pressure, and stiffness) to simulate the actual operating characteristics of relays with different design parameters and to study the influence of mechanical parameters on welding force. The aforementioned patents all employ destructive testing methods for fusion welding force testing. Once the contacts are fused, they become unusable, resulting in high material costs and a long preparation and testing cycle. Furthermore, the experimental results are affected by the randomness of contact surface roughness and microstructure, leading to scattered data. Numerous repeated experiments are required to summarize patterns, making it difficult to meet the need for rapid evaluation of contact fusion welding force.

[0004] Existing methods for analyzing contact welding force are mostly based on idealized contact assumptions and simplified calculation frameworks. For example, they approximate the entire contact surface as a regular or smooth geometry, equate contact behavior to a single contact unit, and employ simplified temperature rise treatments. While these methods facilitate calculation, they often fail to simultaneously reflect the influence of the actual assembly state and the true surface morphology on the contact distribution under short-circuit transient current-carrying conditions. Specifically, factors such as the tilting of the stationary reed, the rotation of the moving reed, and assembly errors can cause changes in the contact closing posture and pressing relationship, thereby altering the contact distribution and local load. Simultaneously, the three-dimensional rough morphology of the contact results in multi-point discrete load-bearing characteristics in the actual contact. Differences in geometry and load among these discrete contact units lead to non-uniform contact resistance and current path space, further causing local temperature rise and melting range differences under short-circuit transient conditions. Oversimplifying this complex contact process to a single equivalent contact makes it difficult to reasonably predict the melting range and welding force, thus limiting the reliability assessment of high-power relays against welding and the optimization design of material structures.

[0005] Therefore, there is a need for a modeling and calculation method that can establish a digital model based on the actual assembly state of the contacts and the real three-dimensional surface morphology of the contacts, and perform correlation modeling on the local contact state, contact resistance, current distribution, temperature rise and melting range of the contacts under a given short-circuit current condition, so as to realize the prediction of welding force and provide technical support for the design and reliability assessment of high-power relays for communication base stations. Summary of the Invention

[0006] This invention aims to address the problem of inaccurate predictions caused by traditional welding force analysis models neglecting the assembly state of paired contacts, the microstructure of the contact surface, and the heating effect of transient short-circuit current. It proposes a method for calculating the welding force of high-power relays in communication base stations that takes into account the surface morphology of the contacts.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for calculating the welding force of a high-power relay in a communication base station, taking into account the surface morphology of the contact points, includes the following steps:

[0009] S1. Obtain the three-dimensional topographic data of the static contact surface and the moving contact surface in the high-power relay of the communication base station, establish the static contact digital model and the moving contact digital model, and perform spatial registration of the static contact digital model and the moving contact digital model according to the actual assembly relationship to form a virtual assembly digital model of the paired contacts, and then perform regularization processing to obtain a regularized virtual assembly digital model.

[0010] S2. Based on the regularized virtual assembly digital model obtained in step S1, simulate the movement of the moving contact relative to the stationary contact to obtain the preset contact indentation depth condition. Iterate through and calculate the height difference between the stationary contact and the moving contact at each grid node in the regularized virtual assembly digital model, identify and extract the interference region between paired contacts, and divide the interference region between paired contacts into multiple independent sub-interference regions.

[0011] S3. Perform quadratic surface fitting on the local point cloud datasets of the static contact surface and the local point cloud datasets of the moving contact surface in each sub-interference region obtained in step S2, and extract the local surface features of the static contact surface region and the local surface features of the moving contact surface region.

[0012] S4. Based on the local surface features of the static and dynamic contact surface regions of each sub-interference region, extract the local interference amount and fit the interference area, then construct the equivalent contact body model of the static and dynamic contacts, and calculate the equivalent contact curvature radius of each sub-interference region;

[0013] S5. For each sub-interference region, using the obtained equivalent contact curvature radius and contact indentation depth, calculate the actual contact area and contact pressure according to the elastic deformation state or plastic deformation state at the contact point;

[0014] S6. Calculate the corresponding contact resistance based on each actual contact area obtained in step S5, and determine the current value flowing through each contact area in combination with the total circuit current.

[0015] S7. Based on the current value, contact resistance, and material electrothermal parameters of each contact area, under the adiabatic assumption, solve the heat balance equation between Joule heat power and material temperature rise, and calculate the highest center temperature of each contact area;

[0016] S8. Based on the highest central temperature of each contact area, material thermal property parameters and heat conduction model obtained in step S7, determine the temperature field distribution of each contact area and its vicinity, and compare the temperature field distribution with the melting temperature and vaporization temperature of the contact material to determine the range of the melting area of ​​each contact area.

[0017] S9. Based on the range of the molten area of ​​each contact area obtained in step S8, calculate the molten area and the corresponding welding force, and calculate the sum of the welding forces of all contact areas to obtain the predicted value of the total welding force of the relay contact.

[0018] Furthermore, the actual assembly relationship in step S1 includes the tilt angle of the stationary contact caused by the installation of the stationary spring and the rotation angle of the moving contact caused by the movement of the moving spring.

[0019] Furthermore, in step S4, the equivalent contact body model of the static and dynamic contacts is constructed by equating the static and dynamic contact surfaces within the sub-interference region to a spherical convex mound-plane contact model with the same interference area and interference amount, and the radius of curvature of the spherical convex mound is calculated as the equivalent contact radius of curvature of each sub-interference region.

[0020] Furthermore, the specific implementation method of step S6 includes the following steps:

[0021] S6.1. For the k-th contact region, the actual contact area A obtained in step S5 is calculated. con k Calculate the true contact radius a of a single equivalent circular spot in the k-th contact region. c k The calculation formula is:

[0022] ;

[0023] Then calculate the contact resistance R of the k-th contact region. c k

[0024]

[0025] Where ρ0 is the resistivity of the contact material;

[0026] S6.2. Based on an insertion depth of d, the total contact resistance of the mating contacts is the result of the parallel connection of the contact resistances of each contact area, and the total contact resistance R is... c The calculation expression is:

[0027]

[0028] Where N is the total number of contact areas;

[0029] S6.3. If the total circuit current is set to the instantaneous short-circuit current that the high-power relay withstands when closed, then when the short-circuit current I passes through the paired contacts, the current I passing through the k-th contact area is... k for:

[0030] .

[0031] Furthermore, the specific implementation method of step S7 includes the following steps:

[0032] S7.1. Based on the short-circuit current I obtained in step S6, the current through the k-th contact region is I. k Calculate the heat generated Q1 k for:

[0033]

[0034] Among them, K f α is the additional loss factor; α is the temperature coefficient of resistance; θ is the temperature.

[0035] The effective heating radius of current contraction is 3a c k In the case of Q2, the heat absorbed by the k-th contact area k for:

[0036]

[0037] Where c and γ are the specific heat capacity and density of the material, respectively;

[0038] Under the adiabatic assumption, according to the law of conservation of energy, the heat balance equation for the k-th contact region of the paired contacts is:

[0039] ;

[0040] S7.2. Set the short-circuit current I k Let be the discrete current values ​​over a time interval Δt, with the start time of current flow taken as 0 and the end time as t. m The starting temperature is θ0, and the ending temperature is θ. m k Integrating the heat balance equation for the k-th contact region yields:

[0041]

[0042] Where n is the time period during which the current is applied [0, t] m The number of time steps after discretization by time interval Δt, n=t m / Δt;

[0043] Then, the highest temperature T at the center of the kth contact area is calculated. max k for:

[0044] .

[0045] Furthermore, in step S7, the heat balance equation is simplified under the adiabatic assumption that the short-circuit current has an extremely short duration, so that all the Joule heat power generated in the contact region is used for the instantaneous temperature rise of the material in that region.

[0046] Furthermore, in step S8, based on the highest central temperature, material thermal properties, and heat conduction process, the temperature field distribution of the k-th contact region and its vicinity is determined as follows:

[0047]

[0048] Among them, cs c l c g These represent the solid-state heat capacity, liquid-state heat capacity, and gas-state heat capacity of the material, respectively, T m T b These are the melting point temperature and boiling point temperature of the material, respectively. ref Let Q be the reference temperature, and Q be the cumulative heat absorbed per unit mass of material in the k-th contact area. m Q is the cumulative heat threshold corresponding to when the material reaches and completes melting. b This is the cumulative heat threshold corresponding to when the material reaches and completes vaporization.

[0049] Furthermore, in step S8, the temperature field distribution of each contact area and its vicinity is determined by calculating the temperature field distribution based on the heat transfer process of the point heat source combined with the highest temperature at the center of each contact area.

[0050] Furthermore, in step S8, the range of the melting region is determined by solving the isothermal surfaces of the melting and vaporization temperatures of the contact material in the temperature field, and by making logical judgments based on the relative relationship between the temperature field distribution and the melting and boiling temperatures of the material.

[0051] Furthermore, in step S9, the predicted total welding force is used to evaluate the weld resistance reliability of the high-power relay.

[0052] The beneficial effects of this invention are:

[0053] The present invention provides a method for calculating the welding force of a high-power relay in a communication base station, which takes into account the surface morphology of the contact points. This method can quantitatively predict the welding force of a high-power relay under short-circuit current conditions, providing a calculation basis for evaluating the anti-welding capability and reliability of high-power relays in communication base stations.

[0054] The present invention provides a method for calculating the welding force of a high-power relay in a communication base station that considers the surface morphology of the contact points. This method incorporates the actual assembly state and indentation depth of the mating contacts into the modeling process, making the welding force assessment results responsive to engineering factors such as assembly errors, tilting, and rotation. This is beneficial for conducting assembly sensitivity analysis and tolerance design during the design phase.

[0055] The present invention provides a method for calculating the welding force of a high-power relay in a communication base station that considers the surface morphology of the contact point. This method can reflect the influence of the actual three-dimensional surface morphology of the contact point on the contact distribution, thereby analyzing the contact area, contact resistance and current distribution under multi-point discrete contact conditions, and avoiding the calculation deviation introduced by simplifying complex contacts into a single equivalent contact.

[0056] The present invention provides a method for calculating the welding force of a high-power relay in a communication base station that considers the surface morphology of the contact point. This method can connect the causal chain between contact state, current distribution, temperature rise response, melting range, and welding force within the same calculation framework. The melting range is determined by using the material melting / vaporization temperature threshold as the boundary, so that the formation of welding force has clear physical criteria to support it.

[0057] The present invention provides a method for calculating the welding force of a high-power relay in a communication base station that takes into account the surface morphology of the contact points. This method can output the range of the molten area, the molten area, and the contribution of each contact area to the total welding force. This facilitates the identification of high-risk locations in the contact structure or assembly state, and provides direct guidance for structural optimization and material parameter adjustment.

[0058] The present invention provides a method for calculating the welding force of high-power relays for communication base stations that considers the surface morphology of contacts. Without relying on a large number of short-circuit tests or prototype iterations, it can be used to conduct parametric comparative evaluations (such as indentation depth, assembly angle, surface morphology features, material parameters, etc.), which helps to shorten the R&D verification cycle and reduce verification costs. This, in turn, is beneficial to the anti-welding reliability design and engineering application evaluation of high-power relays for communication base stations. Attached Figure Description

[0059] Figure 1 This is a flowchart illustrating a method for calculating the welding force of a high-power relay in a communication base station, taking into account the surface morphology of the contact points, according to the present invention.

[0060] Figure 2 Digital models of static contacts, digital models of moving contacts, and digital models of virtual assembly;

[0061] Figure 3 Five discrete interference regions of the virtual assembly digital model under an indentation depth of 2.8 μm;

[0062] Figure 4 The comparison results of the original three-dimensional point cloud data and the fitted surface for the static and dynamic contact sides corresponding to the second sub-interference region;

[0063] Figure 5 Comparison of the original interference area and the fitted interference area at different indentation depths;

[0064] Figure 6 These are the two fitted surface contact bodies and the equivalent contact body corresponding to the second sub-interference region;

[0065] Figure 7 The short-circuit current waveform has a peak value of 1.5kA and a current-carrying time of 1.8ms.

[0066] Figure 8 The temperature field distribution and isotherms of melting and vaporization temperatures in the second contact area are shown.

[0067] Figure 9 A schematic diagram for determining the melting zone based on the highest central temperature, melting temperature, and vaporization temperature;

[0068] Figure 10 The measured distribution of welding force of high-power relays in communication base stations under different contact pressures is compared with the calculated results. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0070] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0071] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 10 Detailed explanation is as follows:

[0072] Example 1:

[0073] A method for calculating the welding force of a high-power relay in a communication base station, taking into account the surface morphology of the contact points, includes the following steps:

[0074] S1. Obtain the three-dimensional topographic data of the static contact surface and the moving contact surface in the high-power relay of the communication base station, establish the static contact digital model and the moving contact digital model, and perform spatial registration of the static contact digital model and the moving contact digital model according to the actual assembly relationship to form a virtual assembly digital model of the paired contacts, and then perform regularization processing to obtain a regularized virtual assembly digital model.

[0075] Furthermore, the actual assembly relationship in step S1 includes the tilt angle of the stationary contact caused by the installation of the stationary spring and the rotation angle of the moving contact caused by the movement of the moving spring.

[0076] Furthermore, the stationary and moving contacts of a high-power relay in a certain type of communication base station were selected as the research objects. First, surface topography height data of the stationary and moving contacts were acquired using a three-dimensional surface topography scanning device to characterize the true geometric features of the contact surfaces. The three-dimensional point cloud datasets P of the stationary and moving contact surfaces are shown. p and P a They are respectively denoted as

[0077]

[0078] ;

[0079] To unify the spatial orientation and coordinate reference of the digital models, spatial translation and rotation transformations are applied to the static contact digital model, aligning its reference plane with a preset reference plane and its centroid with the origin of the coordinate system. Simultaneously, based on the actual assembly state of the paired contacts in the high-power relay of the communication base station, corresponding spatial translation and rotation transformations are applied to the moving contact digital model, ensuring that the static and moving contact digital models form a relative positional relationship in space consistent with their actual assembly state. The spatial transformations of the static and moving contact digital models can be expressed as follows:

[0080] ,

[0081] Among them, R p R a T represents the rotation transformation matrix for the digital model of the stationary contact and the digital model of the moving contact, respectively. p T a These are its translation vectors.

[0082] Through the above spatial transformation, a virtual assembly digital model of the paired contacts is obtained:

[0083]

[0084] in, and These are 3D point cloud datasets of the static and dynamic contact digital models in a virtual assembly state, respectively.

[0085] To facilitate subsequent interference region identification and contact analysis, a virtual assembly digital model was used. Within the paired area, the 3D point cloud datasets of static and dynamic contacts are regularized, transformed and mapped to a unified regular mesh, and the height values ​​at the corresponding mesh nodes are obtained through interpolation, thereby obtaining a regularized virtual assembly digital model.

[0086]

[0087] in, and These are point cloud datasets of static and dynamic contacts in a regularized virtual assembly digital model, respectively.

[0088]

[0089]

[0090] in, , These represent the height values ​​at the regular grid nodes of the static and dynamic contacts, respectively.

[0091] S2. Based on the regularized virtual assembly digital model obtained in step S1, simulate the movement of the moving contact relative to the stationary contact to obtain the preset contact indentation depth condition. Iterate through and calculate the height difference between the stationary contact and the moving contact at each grid node in the regularized virtual assembly digital model, identify and extract the interference region between paired contacts, and divide the interference region between paired contacts into multiple independent sub-interference regions.

[0092] Furthermore, for the regularized virtual assembly digital model, the distance the moving contact moves relative to the stationary contact is the pressing depth d, and the height difference dataset between the stationary and moving contacts at each grid node is calculated by iterating through the data.

[0093] ;

[0094] when When, it is determined that the stationary contact and the moving contact do not interfere; when When the stationary and moving contacts interfere at that spatial location, a set of all interference points is obtained. This set of interference points is then mapped onto the xoy two-dimensional plane to form the interference region between paired contacts.

[0095] ;

[0096] For any interference point in the interference region, examine its eight adjacent positions (top, bottom, left, right, top left, top right, bottom left, bottom right). If its adjacent points are also in the interference region, they are considered to belong to the same connected region. These connected pixel groups are marked as an independent discrete interference region, denoted as Ω. k Repeat this process until all interference points have been calculated, thus obtaining multiple independent sub-interference regions.

[0097] ;

[0098] S3. Perform quadratic surface fitting on the local point cloud datasets of the static contact surface and the local point cloud datasets of the moving contact surface in each sub-interference region obtained in step S2, and extract the local surface features of the static contact surface region and the local surface features of the moving contact surface region.

[0099] Furthermore, for the k-th sub-interference region, point cloud data of the static and dynamic contact surfaces within that interference region are extracted respectively:

[0100]

[0101] ;

[0102] Then, w points are extended around the interference region to accurately reconstruct its morphological features, thereby obtaining the local point cloud dataset of the static and dynamic contact surfaces in the k-th sub-interference region and its surroundings:

[0103]

[0104] ;

[0105] Quadratic surface fitting is performed on the local point cloud datasets of the static and dynamic contact surfaces within the k-th sub-interference region:

[0106]

[0107] ;

[0108] Their matrix forms are as follows:

[0109] ,

[0110] in, , ,

[0111] , , , , ;

[0112] S4. Based on the local surface features of the static and dynamic contact surface regions of each sub-interference region, extract the local interference amount and fit the interference area, then construct the equivalent contact body model of the static and dynamic contacts, and calculate the equivalent contact curvature radius of each sub-interference region;

[0113] Furthermore, in step S4, the equivalent contact body model of the static and dynamic contacts is constructed by equating the static and dynamic contact surfaces within the sub-interference region to a spherical convex mound-plane contact model with the same interference area and interference amount, and the radius of curvature of the spherical convex mound is calculated as the equivalent contact radius of curvature of each sub-interference region.

[0114] Furthermore, for the k-th sub-interference region, the height difference d between the two surfaces after fitting is calculated. k (x, y), define its maximum value d p k The maximum fitted interferometric value in the interference region is the local indentation depth, and the point (x) corresponding to the maximum fitted interferometric value is... c k , y c k This is the point of maximum interference.

[0115]

[0116] ;

[0117] Calculate the fitted interference area A between the two surfaces after fitting the k-th sub-interference region. int k If the static and dynamic contact surfaces within the k-th sub-interference region are equivalent to a spherical mound-plane contact model with the same interference area and interference quantity, then the radius of curvature of the equivalent spherical mound is...

[0118] ;

[0119] S5. For each sub-interference region, using the obtained equivalent contact curvature radius and contact indentation depth, calculate the actual contact area and contact pressure according to the elastic deformation state or plastic deformation state at the contact point;

[0120] Furthermore, for an equivalent radius of curvature of R... k The elastic-plastic deformation of the k-th spherical protrusion depends on the actual indentation depth d. p k With critical indentation depth d c k Relationship

[0121]

[0122] Among them, E * H is the equivalent elastic modulus of the material, and H is the hardness of the material.

[0123] Elastic deformation corresponds to d p k ≤d ck Plastic deformation corresponds to d p k >d c k Actual contact area A con k and the pressure load F con k They are respectively

[0124] ;

[0125] S6. Calculate the corresponding contact resistance based on each actual contact area obtained in step S5, and determine the current value flowing through each contact area in combination with the total circuit current.

[0126] Furthermore, the specific implementation method of step S6 includes the following steps:

[0127] S6.1. For the k-th contact region, the actual contact area A obtained in step S5 is calculated. con k Calculate the true contact radius a of a single equivalent circular spot in the k-th contact region. c k The calculation formula is:

[0128] ;

[0129] Then calculate the contact resistance R of the k-th contact region. c k

[0130]

[0131] Where ρ0 is the resistivity of the contact material;

[0132] S6.2. Based on an insertion depth of d, the total contact resistance of the mating contacts is the result of the parallel connection of the contact resistances of each contact area, and the total contact resistance R is... c The calculation expression is:

[0133]

[0134] Where N is the total number of contact areas;

[0135] S6.3. If the total circuit current is set to the instantaneous short-circuit current that the high-power relay withstands when closed, then when the short-circuit current I passes through the paired contacts, the current I passing through the k-th contact area is... k for:

[0136] .

[0137] S7. Based on the current value, contact resistance, and material electrothermal parameters of each contact area, under the adiabatic assumption, solve the heat balance equation between Joule heat power and material temperature rise, and calculate the highest center temperature of each contact area;

[0138] Furthermore, the specific implementation method of step S7 includes the following steps:

[0139] S7.1. Based on the short-circuit current I obtained in step S6, the current through the k-th contact region is I. k Calculate the heat generated Q1 k for:

[0140]

[0141] Among them, K f α is the additional loss factor; α is the temperature coefficient of resistance; θ is the temperature.

[0142] The effective heating radius of current contraction is 3a c k In the case of Q2, the heat absorbed by the k-th contact area k for:

[0143]

[0144] Where c and γ are the specific heat capacity and density of the material, respectively;

[0145] Under the adiabatic assumption, according to the law of conservation of energy, the heat balance equation for the k-th contact region of the paired contacts is:

[0146] ;

[0147] S7.2. Set the short-circuit current I k Let be the discrete current values ​​over a time interval Δt, with the start time of current flow taken as 0 and the end time as t. m The starting temperature is θ0, and the ending temperature is θ. m k Integrating the heat balance equation for the k-th contact region yields:

[0148]

[0149] Where n is the time period during which the current is applied [0, t] m The number of time steps after discretization by time interval Δt, n=t m / Δt;

[0150] Then, the highest temperature T at the center of the kth contact area is calculated. max k for:

[0151] .

[0152] Furthermore, in step S7, the heat balance equation is simplified under the adiabatic assumption that the short-circuit current has an extremely short duration, so that all the Joule heat power generated in the contact region is used for the instantaneous temperature rise of the material in that region.

[0153] S8. Based on the highest central temperature of each contact area, material thermal property parameters and heat conduction model obtained in step S7, determine the temperature field distribution of each contact area and its vicinity, and compare the temperature field distribution with the melting temperature and vaporization temperature of the contact material to determine the range of the melting area of ​​each contact area.

[0154] Furthermore, when the short-circuit current I(t) passes through the k-th contact region, the highest temperature at its center is T. max k The temperature distribution at a distance r from the center of the heat source can be expressed as:

[0155] ;

[0156] According to the law of conservation of energy, its true energy distribution satisfies the following relationship:

[0157]

[0158] Among them, c s Solid-state heat capacity; T ref The reference temperature is 293K (i.e., ambient temperature).

[0159] For the k-th contact region, from the reference temperature T ref The amount of heat Q absorbed per unit volume when the temperature is raised to T. k It can be represented as

[0160]

[0161] Among them, c s c l c g These represent the solid-state heat capacity, liquid-state heat capacity, and gas-state heat capacity of the material, respectively; T m T b These are the melting point temperature and boiling point temperature of the material, respectively; L m L v These are the latent heat of fusion and latent heat of vaporization of the material, respectively.

[0162] Furthermore, the surface temperature distribution is inverted based on the heat distribution in the contact area. For solid-state heating processes, melting phase transition and liquid-state heating processes, and vaporization phase transition and gas-state heating processes, the temperature T... k The relationship with heat Q can be expressed as:

[0163]

[0164] Among them, c s c l c g These represent the solid-state heat capacity, liquid-state heat capacity, and gas-state heat capacity of the material, respectively, T m T b These are the melting point temperature and boiling point temperature of the material, respectively. ref Let Q be the reference temperature, and Q be the cumulative heat absorbed per unit mass of material in the k-th contact area. m Q is the cumulative heat threshold corresponding to when the material reaches and completes melting. b This is the cumulative heat threshold corresponding to when the material reaches and completes vaporization.

[0165] The relationship between heat Q and temperature T established above k Given the functional relationship, the temperature T of the k-th contact region can be obtained through back interpolation when the input heat Q is known. k The temperature field distribution is plotted as a function of r. The obtained temperature field distribution is compared with the melting and vaporization temperatures of the contact material to determine T. k >T b The region is the vaporization zone, and the distance from the center of the contact area is a. g k ;T k ≈T b The region is the gas-liquid phase transition zone, and the distance to the center of the contact region is a. gl k ;T m <T k <T b The region is the liquid phase region, and the distance to the center of the contact region is a. l k ;T k ≈T m The region is the solid-liquid phase transition region, and the distance from the center of the contact region is a. ls k The gas-liquid phase transition region and the liquid phase region (T) m <T k ≤T b The area that is in contact with the point is the molten region.

[0166] Furthermore, in step S8, the temperature field distribution of each contact area and its vicinity is determined based on the heat transfer process of the point heat source combined with the highest temperature at the center of each contact area. The range of the melting region in step S8 is determined by solving for the isothermal surfaces of the melting and vaporization temperatures of the contact material in the temperature field, and by making logical judgments based on the relative relationship between the temperature field distribution and the melting and boiling points of the material.

[0167] S9. Based on the range of the molten area of ​​each contact area obtained in step S8, calculate the molten area and the corresponding welding force, and calculate the sum of the welding forces of all contact areas to obtain the predicted value of the total welding force of the relay contact.

[0168] Furthermore, in step S9, the predicted total welding force is used to evaluate the weld resistance reliability of the high-power relay.

[0169] Furthermore, for the k-th contact region, its melting area A is calculated. m k for:

[0170] ;

[0171] Then the welding force F in the k-th contact area w k With melting area A m k The calculation expression is:

[0172] ;

[0173] Where Γ represents tensile strength.

[0174] Summarizing the welding forces across all contact areas, the total welding force between mating contacts after a penetration depth of d and a short-circuit current I(t) passing through is:

[0175] .

[0176] The experimental results of this embodiment are further verified as follows:

[0177] 1. Calculation Example

[0178] A case study was conducted using a high-power relay of a certain type of communication base station.

[0179] 2. Calculation process

[0180] (1) Establish the static contact digital model, the moving contact digital model, and the virtual assembly model according to step S1, such as Figure 2 As shown.

[0181] (2) Based on step S2, five discrete interference regions were identified and obtained when the indentation depth was 2.8 μm, such as... Figure 3 As shown.

[0182] (3) Based on the original three-dimensional point cloud data of the static contact surface corresponding to the second sub-interference region obtained in step S3 and the fitted surface, as shown in... Figure 4 As shown in (a), the original three-dimensional point cloud data and the fitted surface of the corresponding moving contact surface are as follows: Figure 4As shown in (b), the comparison of the original interference area and the fitted interference area at different indentation depths is as follows. Figure 5 As shown.

[0183] (4) Based on the contact of the two quadratic fitted surfaces corresponding to the second sub-interference region obtained in step S4, as shown in... Figure 6 As shown in (a), the equivalent sphere-plane contact is as follows: Figure 6 As shown in (b).

[0184] (5) Based on steps S5, S6, S7, S8 and Figure 7 The short-circuit current waveform shown is obtained from calculations with a peak value of 1.5kA and a current-carrying time of 1.8ms. Figure 3 The temperature field distribution and isotherms of melting and vaporization temperatures in the second contact region are shown below. Figure 8 As shown. The gas-liquid phase transition zone and the liquid phase zone of the molten region are as follows. Figure 9 As shown.

[0185] (6) Compare the measured distribution of welding force of high-power relays in communication base stations under different contact pressures obtained in step S9 with the calculated results, such as... Figure 10 As shown.

[0186] 3. Calculate the revenue

[0187] (1) Based on the short-circuit current condition modeling method of a certain type of communication base station high-power relay welding force proposed in this invention, the welding force of the high-power relay was accurately calculated. The welding force calculation result was always within the distribution band of the measured result, which proved the accuracy of the proposed welding force modeling calculation method.

[0188] (2) The comparison results of the original interference area and the fitted interference area at different indentation depths calculated according to the present invention show that the maximum deviation between the original interference area and the fitted interference area does not exceed 10%, which proves the feasibility and accuracy of the surface fitting equivalence.

[0189] (3) The actual contact area and contact resistance under different indentation depths, as well as the temperature distribution of the contact area and the melting area under short-circuit current conditions, can be directly obtained.

[0190] (4) Analyze the calculation results Figure 5 , Figure 10 When the contact pressure is in the range of 1.0~4.0N, the peak short-circuit current is 1.5kA, and the current carrying time is 1.8ms, the actual contact area shows a rapid growth trend with the increase of the pressing depth, and the welding force shows an approximately linear growth trend with the increase of the contact pressure. This is mainly because a larger contact pressure produces a larger contact area, and under the action of the short-circuit current, a larger melting area is generated, which in turn corresponds to a higher welding force.

[0191] (5) The method of the present invention can be used to analyze the influence of contact surface morphology, material properties (resistivity, temperature coefficient of resistance), contact parameters (contact pressure, radius of curvature of arc surface), and short-circuit current (peak value, current carrying time) on the welding force of high-power relays. The obtained data can be directly used for the reliability optimization design and anti-welding capability improvement of high-power relays.

[0192] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0193] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for calculating the welding force of a high-power relay in a communication base station, considering the surface morphology of the contact points, characterized in that, The steps include the following: S1. Obtain the three-dimensional topographic data of the static contact surface and the moving contact surface in the high-power relay of the communication base station, establish the static contact digital model and the moving contact digital model, and perform spatial registration of the static contact digital model and the moving contact digital model according to the actual assembly relationship to form a virtual assembly digital model of the paired contacts, and then perform regularization processing to obtain a regularized virtual assembly digital model. S2. Based on the regularized virtual assembly digital model obtained in step S1, simulate the movement of the moving contact relative to the stationary contact to obtain the preset contact indentation depth condition. Iterate through and calculate the height difference between the stationary contact and the moving contact at each grid node in the regularized virtual assembly digital model, identify and extract the interference region between paired contacts, and divide the interference region between paired contacts into multiple independent sub-interference regions. S3. Perform quadratic surface fitting on the local point cloud datasets of the static contact surface and the local point cloud datasets of the moving contact surface in each sub-interference region obtained in step S2, and extract the local surface features of the static contact surface region and the local surface features of the moving contact surface region. S4. Based on the local surface features of the static and dynamic contact surface regions of each sub-interference region, extract the local interference amount and fit the interference area, then construct the equivalent contact body model of the static and dynamic contacts, and calculate the equivalent contact curvature radius of each sub-interference region; S5. For each sub-interference region, using the obtained equivalent contact curvature radius and contact indentation depth, calculate the actual contact area and contact pressure according to the elastic deformation state or plastic deformation state at the contact point; S6. Calculate the corresponding contact resistance based on each actual contact area obtained in step S5, and determine the current value flowing through each contact area in combination with the total circuit current. S7. Based on the current value, contact resistance, and material electrothermal parameters of each contact area, under the adiabatic assumption, solve the heat balance equation between Joule heat power and material temperature rise, and calculate the highest center temperature of each contact area; S8. Based on the highest central temperature of each contact area, material thermal property parameters and heat conduction model obtained in step S7, determine the temperature field distribution of each contact area and its vicinity, and compare the temperature field distribution with the melting temperature and vaporization temperature of the contact material to determine the range of the melting area of ​​each contact area. S9. Based on the range of the molten area of ​​each contact area obtained in step S8, calculate the molten area and the corresponding welding force, and calculate the sum of the welding forces of all contact areas to obtain the predicted value of the total welding force of the relay contact.

2. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 1, is characterized in that... The actual assembly relationship in step S1 includes the tilt angle of the stationary contact caused by the installation of the stationary spring and the rotation angle of the moving contact caused by the movement of the moving spring.

3. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 2, is characterized in that... In step S4, the equivalent contact body model of the static and dynamic contacts is constructed by equating the static and dynamic contact surfaces within the sub-interference region to a spherical convex mound-plane contact model with the same interference area and interference amount, and calculating the radius of curvature of the spherical convex mound as the equivalent contact radius of curvature of each sub-interference region.

4. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 3, is characterized in that... The specific implementation method of step S6 includes the following steps: S6.

1. For the k-th contact region, the actual contact area A obtained in step S5 is calculated. con k Calculate the true contact radius a of a single equivalent circular spot in the k-th contact region. c k The calculation formula is: ； Then calculate the contact resistance R of the k-th contact region. c k Where ρ0 is the resistivity of the contact material; S6.

2. Based on an insertion depth of d, the total contact resistance of the mating contacts is the result of the parallel connection of the contact resistances of each contact area, and the total contact resistance R is... c The calculation expression is: Where N is the total number of contact areas; S6.

3. If the total circuit current is set to the instantaneous short-circuit current that the high-power relay withstands when closed, then when the short-circuit current I passes through the paired contacts, the current I passing through the k-th contact area is... k for: 。 5. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 4, is characterized in that... The specific implementation method of step S7 includes the following steps: S7.

1. Based on the short-circuit current I obtained in step S6, the current through the k-th contact region is I. k Calculate the heat generated Q1 k for: Among them, K f α is the additional loss factor; α is the temperature coefficient of resistance; θ is the temperature. The effective heating radius of current contraction is 3a c k In the case of Q2, the heat absorbed by the k-th contact area k for: Where c and γ are the specific heat capacity and density of the material, respectively; Under the adiabatic assumption, according to the law of conservation of energy, the heat balance equation for the k-th contact region of the paired contacts is: ； S7.

2. Set the short-circuit current I k Let be the discrete current values ​​over a time interval Δt, with the start time of current flow taken as 0 and the end time as t. m The starting temperature is θ0, and the ending temperature is θ. m k Integrating the heat balance equation for the k-th contact region yields: Where n is the time period during which the current is applied [0, t] m The number of time steps after discretization by time interval Δt, n=t m / Δt; Then, the highest temperature T at the center of the kth contact area is calculated. max k for: 。 6. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 5, is characterized in that... In step S7, the heat balance equation is simplified under the adiabatic assumption that the short-circuit current has an extremely short duration, so that all the Joule heat power generated in the contact region is used for the instantaneous temperature rise of the material in that region.

7. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 6, is characterized in that... In step S8, based on the highest central temperature, material thermophysical parameters, and heat conduction process, the temperature field distribution of the k-th contact region and its vicinity is determined as follows: Among them, c s c l c g These represent the solid-state heat capacity, liquid-state heat capacity, and gas-state heat capacity of the material, respectively, T m T b These are the melting point temperature and boiling point temperature of the material, respectively. ref Let Q be the reference temperature, and Q be the cumulative heat absorbed per unit mass of material in the k-th contact area. m Q is the cumulative heat threshold corresponding to when the material reaches and completes melting. b This is the cumulative heat threshold corresponding to when the material reaches and completes vaporization.

8. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 7, is characterized in that... In step S8, the temperature field distribution of each contact area and its vicinity is determined by calculating the temperature field distribution based on the heat transfer process of the point heat source and the highest temperature at the center of each contact area.

9. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 8, is characterized in that... In step S8, the range of the melting region is determined by solving the isothermal surfaces of the melting and vaporization temperatures of the contact material in the temperature field, and by making logical judgments based on the relative relationship between the temperature field distribution and the melting and boiling temperatures of the material.

10. The method for calculating the welding force of a high-power relay in a communication base station considering the surface morphology of the contact points, as described in claim 9, is characterized in that... In step S9, the predicted total welding force is used to evaluate the weld resistance reliability of the high-power relay.

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