Method and system for determining pressure in the interior space of a medium frequency vacuum arc

Abstract

The application discloses a kind of internal space pressure determination method and system of medium frequency vacuum arc, it is related to vacuum switch field, the method includes: in the process of medium frequency vacuum arc discharge, using binocular camera obtains the binocular vision arc image of each sampling time;The binocular vision arc image includes left arc image and right arc image;According to the binocular vision arc image of each sampling time, using binocular stereo imaging algorithm determines the three-dimensional coordinates of metal droplet at each sampling time;The metal droplet is the metal droplet that metal contact of vacuum switch is spattered out when arc discharge;Based on the three-dimensional coordinates of metal droplet at each sampling time determines the radius and acceleration of each time in the space migration movement process of metal droplet;According to the radius and acceleration of metal droplet at each time determines the internal pressure of vacuum arc at each time.The application is a kind of non-contact plasma measurement method, improves the accuracy of internal space pressure calculation of medium frequency vacuum arc.

Description

Technical Field

[0001] This invention relates to the field of vacuum switch technology, and in particular to a method and system for determining the internal space pressure of a medium-frequency vacuum arc. Background Technology

[0002] In variable frequency (360–800 Hz) power systems for multi-electric aircraft, the increased frequency leads to a higher rate of current change, making arc extinguishing more difficult. The breaking capacity of electrical components becomes a technical bottleneck for high-power aviation power supply and distribution protection. Applying vacuum switches to variable frequency power systems holds promise for overcoming these challenges. Analyzing the complex physical processes within a medium-frequency vacuum arc is not only cutting-edge research in electrical engineering but also crucial for improving the performance of arc-extinguishing chambers.

[0003] Currently, the main methods for studying medium-frequency vacuum arcs are experimental methods and simulation calculations. Experiments can obtain a series of important physical parameters of the medium-frequency vacuum arc discharge process; comprehensive and accurate parameters are the foundation and key to obtaining high-precision simulation results. The internal pressure of the arc is an important parameter in the discharge process; it is the force macroscopically manifested by the state of the plasma due to the interaction of electric, magnetic, and thermal fields during arc discharge. Arc pressure directly affects the formation of the plasma jet and the evolution of the medium-frequency vacuum arc morphology, as well as the diffusion and accumulation of the arc. It also acts on the molten metal droplets generated at the contacts, influencing the post-arc breakdown process through jet motion. Due to the special environment of the vacuum interrupter, the arc pressure cannot be measured by sensors and can only be obtained through indirect calculation methods. In the journal article “Analysis of Vacuum Arc Breaking Process and Droplet Ejection in Medium Frequency Power Supply System” (Jiang Yuan, et al. Analysis of Vacuum Arc Breaking Process and Droplet Ejection in Medium Frequency Power Supply System [J]. Proceedings of the CSEE, 2020, 40(02): 684-692.), a method for indirectly calculating arc pressure by means of experimentally captured arc images was proposed. However, this calculation method can only obtain the pressure in the image plane and lacks spatial third-dimensional information, resulting in low calculation accuracy. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for determining the internal space pressure of a medium-frequency vacuum arc, thereby improving the accuracy of calculating the internal space pressure of a medium-frequency vacuum arc.

[0005] To achieve the above objectives, the present invention provides the following solution.

[0006] A method for determining the internal pressure of a medium-frequency vacuum arc includes:

[0007] During the mid-frequency vacuum arc discharge process, a binocular camera is used to obtain dual-view arc images at each sampling time; the dual-view arc images include a left arc image and a right arc image;

[0008] Based on the dual-view arc images at each sampling time, the three-dimensional coordinates of the metal droplets at each sampling time are determined using a binocular stereo imaging algorithm; the metal droplets are the metal droplets splashed out by the metal contacts of the vacuum switch during arc discharge.

[0009] The radius and acceleration of the metal droplet at each sampling time are determined based on the three-dimensional coordinates of the metal droplet during its spatial migration.

[0010] The internal pressure of the vacuum arc at each moment is determined based on the radius and acceleration of the metal droplet at each moment.

[0011] Optionally, based on the dual-view arc images at each sampling time, a binocular stereo imaging algorithm is used to determine the three-dimensional coordinates of the metal droplet at each sampling time, specifically including:

[0012] The binocular camera is calibrated to obtain its intrinsic and extrinsic parameters;

[0013] Preprocessing and feature extraction are performed on each of the dual-view arc images to extract the metal droplets in the dual-view arc images and obtain the feature-extracted image; the metal droplets are the metal droplets splashed out by the metal contacts of the vacuum switch during arc discharge;

[0014] Based on the intrinsic and extrinsic parameters of the binocular camera, stereo correction is performed on the feature-extracted image to obtain the corrected left arc feature image and the corrected right arc feature image.

[0015] The corrected left and right arc feature images are stereo matched to determine the three-dimensional coordinates of the metal droplet at each sampling time.

[0016] Optionally, determining the internal pressure of the vacuum arc at each moment based on the radius and acceleration of the metal droplet specifically includes:

[0017] According to the formula Calculate the pressure gradient along the direction of motion of the metal droplet;

[0018] The pressure inside the vacuum arc is determined by integrating the pressure gradient along the direction of metal droplet motion.

[0019] in, m The mass of the metal droplet. a For acceleration, F For the forces acting on the molten metal droplet, r Let be the radius of the metal droplet. θ Let be the zenith angle of the liquid metal droplet in spherical coordinates. Let be the azimuth angle of the metal droplet in spherical coordinates. The pressure gradient is along the direction of the metal droplet's movement. Including the pressure gradient in the x-direction Pressure gradient in the y direction and pressure gradient in the z-direction ;

[0020] ;

[0021] in, a x Let x be the acceleration in the x-direction. a y Let be the acceleration in the y-direction. a z Let z be the acceleration in the z-direction.

[0022] Optionally, when calibrating the binocular camera, the method further includes determining the mapping relationship between the arc image pixel coordinate system and the camera coordinate system.

[0023] Optionally, stereo correction is performed on the feature-extracted image based on the intrinsic and extrinsic parameters of the binocular camera to obtain a corrected left arc feature image and a corrected right arc feature image, specifically including:

[0024] Based on the mapping relationship between the arc image pixel coordinate system and the camera coordinate system, the feature-extracted image is transformed from the arc image pixel coordinate system to the camera coordinate system, and parallel epipolar correction and distortion correction are performed. The corrected image is then restored from the camera coordinate system to the arc image pixel coordinate system to obtain the corrected arc feature image, which includes the corrected left arc feature image and the corrected right arc feature image.

[0025] Optionally, determining the radius and acceleration of the metal droplet at each sampling moment based on its three-dimensional coordinates specifically includes:

[0026] Based on the three-dimensional coordinates of the metal droplet at each sampling time, the acceleration at each moment during the spatial migration of the metal droplet is determined using the frame difference method.

[0027] This invention also discloses a system for determining the internal space pressure of a medium-frequency vacuum arc, comprising:

[0028] A dual-view arc image acquisition module is used to acquire dual-view arc images at each sampling time during the mid-frequency vacuum arc discharge process using a binocular camera; the dual-view arc images include a left arc image and a right arc image;

[0029] The three-dimensional coordinate determination module for the metal droplet is used to determine the three-dimensional coordinates of the metal droplet at each sampling time using a binocular stereo imaging algorithm based on the dual-view arc images at each sampling time; the metal droplet is the metal droplet splashed out by the metal contact of the vacuum switch during arc discharge;

[0030] An acceleration and radius determination module is used to determine the radius and acceleration of a metal droplet at each moment during its spatial migration motion based on the three-dimensional coordinates of the metal droplet at each sampling time.

[0031] The vacuum arc internal pressure determination module is used to determine the vacuum arc internal pressure at each moment based on the radius and acceleration of the metal droplet.

[0032] According to specific embodiments provided by the present invention, the following technical effects are disclosed.

[0033] This invention utilizes a binocular camera to obtain dual-view arc images at each sampling time, and employs a binocular stereo imaging algorithm to determine the three-dimensional motion trajectory of the metal droplet during its spatial migration, thereby obtaining the internal pressure of the vacuum arc in three-dimensional space and improving the accuracy of the calculation of the internal pressure of the vacuum arc. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the process for determining the internal space pressure of a medium-frequency vacuum arc according to the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of each component in the medium-frequency vacuum arc experiment of this invention.

[0037] Figure 3 This is a schematic diagram of a mid-frequency vacuum arc and a metal droplet captured by the high-speed camera of this invention.

[0038] Figure 4 This is a schematic diagram of the internal space pressure determination system of a medium-frequency vacuum arc according to the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The purpose of this invention is to provide a method and system for determining the internal space pressure of a medium-frequency vacuum arc, thereby improving the accuracy of the calculation of the internal space pressure of a medium-frequency vacuum arc.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Current mainstream theoretical research suggests that post-arc breakdown in power frequency (50Hz) vacuum arcs is caused by contact overheating due to anode spots, leading to post-arc breakdown. In contrast, mid-frequency (360~800Hz) vacuum arcs do not exhibit anode spots and have lower contact temperatures; their post-arc breakdown is induced by molten metal droplets. This has been confirmed experimentally. Under the same current conditions, molten metal droplets are more easily observed in images during mid-frequency (360~800Hz) experiments. This invention utilizes this advantage to calculate the internal spatial pressure of mid-frequency vacuum arcs.

[0043] like Figure 1 As shown, the method for determining the internal space pressure of a medium-frequency vacuum arc according to the present invention includes the following steps.

[0044] Step 101: During the mid-frequency vacuum arc discharge process, a binocular camera is used to obtain dual-view arc images at each sampling time; the dual-view arc images include a left arc image and a right arc image.

[0045] like Figure 2 As shown, both cameras in the binocular camera are high-speed cameras (high-speed camera 1 and high-speed camera 2). In the mid-frequency vacuum arc experiment, two high-speed cameras are used to obtain dual-view arc images.

[0046] In the medium-frequency vacuum arc experiment, a computer control and processing system is used to control the medium-frequency vacuum arc generating circuit to generate a medium-frequency vacuum arc in the medium-frequency vacuum arc extinguishing chamber. The dual-view arc images captured synchronously by two high-speed cameras are used to realize the method for determining the internal space pressure of a medium-frequency vacuum arc according to the present invention.

[0047] This invention has two characteristics for conducting medium-frequency vacuum arc experiments. First, because the medium-frequency (360Hz~800Hz) vacuum arc has a shorter cycle, shorter arc burning time, and faster arc change speed, it requires a high-speed camera with a higher sampling rate (7 to 16 times higher) than when shooting power frequency (50Hz) arcs. Second, experimental results show that with the same current, it is easier to observe metal droplets in the image during medium-frequency experiments. This invention uses the movement of metal droplets to calculate arc pressure.

[0048] Step 102: Based on the dual-view arc images at each sampling time, use a binocular stereo imaging algorithm to determine the three-dimensional coordinates of the metal droplets at each sampling time; the metal droplets are the metal droplets splashed out by the metal contacts of the vacuum switch during arc discharge.

[0049] Figure 3The image in the middle is a schematic diagram of a mid-frequency vacuum arc and a metal droplet, captured by a high-speed camera. Figure 3 In the middle (a), the frequency is... f Under the condition of 360Hz, t 1. t 2. t 3. t 4 and t 5. Vacuum arc and metal droplet at 5 different moments. i 1. i 2. i 3. i 4 and i 5 are respectively t 1. t 2. t 3. t 4 and t The current of the vacuum arc corresponding to 5. Figure 3 (b) represents the frequency. f Vacuum arc and metal droplet at 500Hz at 5 time points. Figure 3 (c) represents the frequency. f Vacuum arc and metal droplet at 5 time points under 600Hz conditions.

[0050] Step 102 specifically includes:

[0051] The stereo camera is calibrated to obtain its intrinsic and extrinsic parameters.

[0052] When calibrating the binocular camera, the process also includes determining the mapping relationship between the arc image pixel coordinate system, the camera coordinate system, the arc image coordinate system, and the world coordinate system.

[0053] The specific methods for calibrating a binocular camera include: taking pictures of a reference object from different angles, using a black and white calibration board as a reference object, extracting the black and white grid vertices in the reference object, and using a transformation matrix to obtain the focal length, image center point coordinates, camera position coordinates, rotation matrix and translation variables between the left and right cameras, as well as other internal and external parameters; and establishing the mapping relationship between the arc image pixel coordinate system, the arc image coordinate system, the camera coordinate system, and the world coordinate system.

[0054] The dual-view arc images are preprocessed and feature extracted to extract metal droplets from the dual-view arc images, obtaining a feature-extracted image; the metal droplets are metal droplets splashed from the metal contacts of the vacuum switch during arc discharge. This step specifically includes: firstly, using Gaussian filtering to reduce image noise; then, based on the difference in grayscale values ​​between the metal droplets in the arc image and the surrounding environment, comparing and extracting features to obtain the feature-extracted image.

[0055] As a specific implementation method, an edge detection algorithm is used to extract features from the preprocessed arc image to obtain the feature-extracted image.

[0056] Based on the intrinsic and extrinsic parameters of the binocular camera, stereo correction is performed on the feature-extracted image to obtain the corrected left arc feature image and the corrected right arc feature image. This step specifically includes:

[0057] Based on the mapping relationship between the arc image pixel coordinate system and the camera coordinate system, the feature-extracted images (the left and right arc images after feature extraction) are transformed from the arc image pixel coordinate system to the camera coordinate system. Parallel epipolar correction and distortion correction are then performed. The corrected images are then restored from the camera coordinate system to the arc image pixel coordinate system to obtain the corrected arc feature images. The corrected arc feature images include the corrected left arc feature images and the corrected right arc feature images.

[0058] The stereo calibration of this invention uses parameters determined by two cameras to correct the arc images captured by the left and right cameras, so as to achieve the effect of being in the same plane and coplanar, which can reduce the computational complexity of subsequent stereo matching.

[0059] The corrected left and right arc feature images are stereo matched to determine the three-dimensional coordinates of the metal droplet at each sampling time.

[0060] Due to the different spatial positions of the left and right cameras, the two arc images captured will exhibit horizontal and depth parallax on the imaging plane. Therefore, stereo matching is used to establish the correspondence between each pair of images (arc images obtained by the left and right cameras at the same sampling time). The stereo matching method specifically includes: firstly, selecting pixel p1 in one of the two arc images to establish a dynamic matching window; then, linearly scanning the dynamic matching window in the other arc image, and identifying the feature point p2 with the highest similarity.

[0061] Based on the aforementioned steps of binocular camera calibration, metal droplet extraction, and stereo matching, this invention obtains the camera's intrinsic and extrinsic parameters, the mapping relationship between the arc image coordinate system and the world coordinate system, and uses the principles of triangulation and parallax to calculate the three-dimensional coordinates of the metal droplet.

[0062] Step 103: Determine the radius and acceleration of the metal droplet at each sampling time based on the three-dimensional coordinates of the metal droplet during its spatial migration.

[0063] Step 103 specifically includes:

[0064] Based on the three-dimensional coordinates of the metal droplet at each sampling time, the acceleration at each moment during the spatial migration of the metal droplet is determined using the frame difference method.

[0065] An edge detection algorithm is used to determine the region of the metal droplet, thereby determining the radius of the metal droplet.

[0066] This invention establishes a spatial coordinate system and uses physical properties such as the density and size of the metal droplets, as well as spatial motion parameters such as acceleration, to obtain the pressure distribution inside the vacuum arc.

[0067] Step 104: Determine the internal pressure of the vacuum arc at each moment based on the radius and acceleration of the metal droplet at each moment.

[0068] Step 104 specifically includes:

[0069] According to the formula Calculate the pressure gradient along the direction of motion of the metal droplet.

[0070] The pressure inside the vacuum arc is determined by integrating the pressure gradient along the direction of the metal droplet's movement, thus obtaining the pressure distribution inside the vacuum arc.

[0071] in, F The external force driving the migration and motion of the metal droplets. m The mass of the metal droplet. a Let be the acceleration of the metal droplet's spatial migration motion. a x , a y and a z constitute a , a x , a y , a z These are the accelerations in the x, y, and z directions, respectively. r Let be the radius of the metal droplet. θ Let be the zenith angle of the liquid metal droplet in spherical coordinates. Let be the azimuth angle of the metal droplet in spherical coordinates. The pressure gradient is along the direction of the metal droplet's movement. , , These are the pressure gradients in the x, y, and z directions, respectively. , and constitute .

[0072] radius of metal droplets r The image is determined by feature extraction.

[0073] The pressure inside a vacuum arc decreases from the center outwards, while the molten metal droplets migrate from the inside of the arc outwards. Therefore, the pressure inside the vacuum arc in the above formula has a negative sign.

[0074] The method of this invention utilizes the principle of stereoscopic imaging to calculate the spatial pressure inside a mid-frequency vacuum arc based on dual-view arc images. This compensates for the information loss caused by analyzing the post-arc process using two-dimensional motion equations, and can provide important evidence for a more detailed explanation of the jet formation, morphological changes, and post-arc breakdown phenomenon of mid-frequency vacuum arcs.

[0075] Figure 4 This is a schematic diagram of a system for determining the internal space pressure of a medium-frequency vacuum arc according to the present invention. Figure 4 As shown, a system for determining the internal space pressure of a medium-frequency vacuum arc includes:

[0076] The dual-view arc image acquisition module 201 is used to acquire dual-view arc images at each sampling time using a binocular camera during the mid-frequency vacuum arc discharge process; the dual-view arc images include a left arc image and a right arc image.

[0077] The three-dimensional coordinate determination module 202 for metal droplets is used to determine the three-dimensional coordinates of the metal droplets at each sampling time using a binocular stereo imaging algorithm based on the dual-view arc images at each sampling time; the metal droplets are metal droplets splashed out by the metal contacts of the vacuum switch during arc discharge.

[0078] The acceleration and radius determination module 203 is used to determine the radius and acceleration of the metal droplet at each moment during its spatial migration motion based on the three-dimensional coordinates of the metal droplet at each sampling time.

[0079] The vacuum arc internal pressure determination module 204 is used to determine the vacuum arc internal pressure at each moment based on the radius and acceleration of the metal droplet at each moment.

[0080] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0081] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining the internal pressure of a medium-frequency vacuum arc, characterized in that, include: During the mid-frequency vacuum arc discharge process, a binocular camera is used to obtain dual-view arc images at each sampling time; the dual-view arc images include a left arc image and a right arc image; Based on the dual-view arc images at each sampling time, a binocular stereo imaging algorithm is used to determine the three-dimensional coordinates of the metal droplet at each sampling time. Specifically, this includes: calibrating the binocular camera to obtain its intrinsic and extrinsic parameters; using Gaussian filtering to reduce image noise; and then comparing and extracting features based on the difference between the grayscale value of the metal droplet in the arc image and the surrounding environment to obtain the feature-extracted image; the metal droplet is the metal droplet ejected from the metal contact of the vacuum switch during arc discharge; performing stereo correction on the feature-extracted image based on the intrinsic and extrinsic parameters of the binocular camera to obtain the corrected left arc feature image and the corrected right arc feature image; performing stereo matching on the corrected left arc feature image and the corrected right arc feature image; firstly, selecting pixel p1 in one of the two arc images to establish a dynamic matching window; then linearly scanning the dynamic matching window in the other arc image; the feature point p2 with the highest similarity is the best match, and finally determining the three-dimensional coordinates of the metal droplet at each sampling time. The radius and acceleration of the metal droplet during its spatial migration are determined based on the three-dimensional coordinates of the metal droplet at each sampling time. Specifically, this includes: determining the acceleration of the metal droplet during its spatial migration using the frame difference method based on the three-dimensional coordinates of the metal droplet at each sampling time; and determining the region of the metal droplet using an edge detection algorithm, thereby determining the radius of the metal droplet. The internal pressure of the vacuum arc at each moment is determined based on the radius and acceleration of the molten metal droplet. Specifically, this includes: using the formula... Calculate the pressure gradient along the direction of metal droplet motion; integrate the pressure gradient along the direction of metal droplet motion to determine the internal pressure of the vacuum arc; where... m The mass of the metal droplet, a For acceleration, F For the forces acting on the molten metal droplet, r Let be the radius of the metal droplet. θ Let be the zenith angle of the liquid metal droplet in spherical coordinates. Let be the azimuth angle of the metal droplet in spherical coordinates. The pressure gradient is along the direction of the metal droplet's movement. Including the pressure gradient in the x-direction Pressure gradient in the y direction and pressure gradient in the z-direction ; ； in, a x Let x be the acceleration in the x-direction. a y Let be the acceleration in the y-direction. a z The acceleration is in the z-direction; the pressure inside the vacuum arc decreases from the center outwards, while the molten metal droplets migrate from the inside of the arc outwards, hence the negative sign in the formula; by utilizing the principle of stereoscopic imaging, the spatial pressure inside the mid-frequency vacuum arc can be calculated based on the dual-view arc image, thus compensating for the information loss caused by analyzing the post-arc process using two-dimensional motion equations.

2. The method for determining the internal space pressure of a medium-frequency vacuum arc according to claim 1, characterized in that, When calibrating the binocular camera, the process also includes determining the mapping relationship between the arc image pixel coordinate system and the camera coordinate system.

3. The method for determining the internal space pressure of a medium-frequency vacuum arc according to claim 2, characterized in that, Based on the intrinsic and extrinsic parameters of the binocular camera, stereo correction is performed on the feature-extracted image to obtain the corrected left arc feature image and the corrected right arc feature image, specifically including: Based on the mapping relationship between the arc image pixel coordinate system and the camera coordinate system, the feature-extracted image is transformed from the arc image pixel coordinate system to the camera coordinate system, and parallel epipolar correction and distortion correction are performed. The corrected image is then restored from the camera coordinate system to the arc image pixel coordinate system to obtain the corrected arc feature image, which includes the corrected left arc feature image and the corrected right arc feature image.

4. A system for determining the internal pressure of a medium-frequency vacuum arc, characterized in that, include: A dual-view arc image acquisition module is used to acquire dual-view arc images at each sampling time during the mid-frequency vacuum arc discharge process using a binocular camera; the dual-view arc images include a left arc image and a right arc image; The 3D coordinate determination module for the metal droplet is used to determine the 3D coordinates of the metal droplet at each sampling time using a binocular stereo imaging algorithm based on dual-view arc images at each sampling time. Specifically, it includes: calibrating the binocular camera to obtain its intrinsic and extrinsic parameters; using Gaussian filtering to reduce image noise; and then comparing and extracting features based on the difference between the grayscale value of the metal droplet in the arc image and the surrounding environment to obtain a feature-extracted image; the metal droplet is the metal droplet ejected from the metal contacts of a vacuum switch during arc discharge; performing stereo correction on the feature-extracted image based on the intrinsic and extrinsic parameters of the binocular camera to obtain a corrected left arc feature image and a corrected right arc feature image; performing stereo matching on the corrected left and right arc feature images; firstly, selecting pixel p1 in one of the two arc images to establish a dynamic matching window; then linearly scanning the dynamic matching window in the other arc image; the feature point p2 with the highest similarity is the best match, ultimately determining the 3D coordinates of the metal droplet at each sampling time. The acceleration and radius determination module is used to determine the radius and acceleration of the metal droplet at each sampling time based on the three-dimensional coordinates of the metal droplet at each sampling time. Specifically, it includes: determining the acceleration of the metal droplet at each sampling time using the frame difference method based on the three-dimensional coordinates of the metal droplet at each sampling time; and determining the region of the metal droplet using an edge detection algorithm, thereby determining the radius of the metal droplet. The vacuum arc internal pressure determination module is used to determine the internal pressure of the vacuum arc at various times based on the radius and acceleration of the molten metal droplet. Specifically, it includes: determining the internal pressure of the vacuum arc at different times based on the formula... Calculate the pressure gradient along the direction of metal droplet motion; integrate the pressure gradient along the direction of metal droplet motion to determine the internal pressure of the vacuum arc; where... m The mass of the metal droplet, a For acceleration, F For the forces acting on the molten metal droplet, r Let be the radius of the metal droplet. θ Let be the zenith angle of the liquid metal droplet in spherical coordinates. Let be the azimuth angle of the metal droplet in spherical coordinates. The pressure gradient is along the direction of the metal droplet's movement. Including the pressure gradient in the x-direction Pressure gradient in the y direction and pressure gradient in the z-direction ; ； in, a x Let x be the acceleration in the x-direction. a y Let be the acceleration in the y-direction. a z The acceleration is in the z-direction; the pressure inside the vacuum arc decreases from the center outwards, while the molten metal droplets migrate from the inside of the arc outwards, hence the negative sign in the formula; by utilizing the principle of stereoscopic imaging, the spatial pressure inside the mid-frequency vacuum arc can be calculated based on the dual-view arc image, thus compensating for the information loss caused by analyzing the post-arc process using two-dimensional motion equations.

Images