Electromagnetic shielding design method of double-body sealed case for strand breaking robot

Abstract

An electromagnetic shielding design method of a double-body sealed case for a strand breaking robot aims to solve the problem that internal electrical elements are easily interfered when the strand breaking robot works in a strong electromagnetic environment, and comprises the following steps: firstly, optimizing a case body structure based on a shielding effect, adopting a full-sealing design and strictly controlling the number of circular holes; the box body is divided into a left body and a right body and is provided with an openable cover plate; secondly, carrying out electric shielding and magnetic shielding design, and deducing and establishing an electric field and magnetic field shielding effectiveness calculation model through a charge distribution rule and a magnetic resistance parallel circuit; then permalloy with high conductivity and high magnetic conductivity is selected as a core shielding material and subjected to film coating treatment; then, double protection of non-permanent seam shielding combined with conductive gasket installation is adopted for the box body gap; and finally verifying the electric field intensity and the magnetic induction intensity in the shielded box body through electromagnetic simulation to ensure that the public exposure electromagnetic field intensity limit value requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding design technology, specifically relating to an electromagnetic shielding design method for a double-body sealed chassis for a strand-breaking robot. Background Technology

[0002] With the intelligent upgrading of power systems, the strand-breaking robot, as a key piece of equipment for the inspection and maintenance of transmission lines, needs to operate in strong electromagnetic environments such as under 110kV and above high-voltage transmission lines for a long time. The operation of high-voltage transmission lines generates high-intensity power frequency electric and magnetic fields. If the enclosure lacks effective electromagnetic shielding measures, the external electromagnetic field can easily penetrate the enclosure and interfere with the normal operation of internal electrical components, leading to a decrease in robot control accuracy, abnormal data transmission, and even damage to components, seriously affecting the safety and reliability of the operation.

[0003] Existing strand-breaking robot chassis mostly use traditional metal materials and simple sealed structures, which have the following shortcomings: First, the structural design does not fully consider electromagnetic shielding requirements, and the form and number of openings are unreasonable, which can easily form electromagnetic leakage channels; Second, the selection of shielding materials lacks specificity, and the material parameters are not optimized in combination with the dual requirements of electric field and magnetic field shielding, resulting in limited shielding effectiveness; Third, the sealing and shielding design at the joints of the chassis are not perfect, and the gaps in the openable structure can easily become weak points for electromagnetic leakage; Fourth, there is a lack of a systematic shielding effectiveness calculation and simulation verification process, making it difficult to accurately ensure that the shielding effect meets safety standards.

[0004] Meanwhile, the working environment of the strand-breaking robot is complex, and it needs to withstand the influence of natural factors such as wind, rain and corrosion. The chassis also needs to take into account both sealing protection and the convenience of installation and maintenance. The traditional single electromagnetic shielding design can no longer meet the comprehensive needs under complex working conditions.

[0005] Therefore, there is an urgent need for an electromagnetic shielding design method that takes into account structural rationality, material compatibility, comprehensive protection, and verifiable effectiveness, which has become a key technical challenge to improve the operational stability and service life of strand-breaking robots. Summary of the Invention

[0006] The technical problem to be solved by this invention is an electromagnetic shielding design method for a double-body sealed chassis for a strand-breaking robot, which can take into account the rationality of structure, material compatibility, comprehensive protection and verifiable effect for the strand-breaking robot.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot includes the following steps: S1. Based on the electromagnetic shielding effect, the structure of the box of the strand-breaking robot is designed; S2, Electromagnetic shielding design for the casing of the strand-breaking robot; S3, Select the shielding material for the casing of the strand-breaking robot; S4. Considering both the structure and material of the strand-breaking robot housing, electromagnetic shielding design is implemented for the holes and gaps in the strand-breaking robot housing.

[0008] In the design of the structure of the strand-breaking robot housing, S1 should be considered when designing the structure of the robot housing to ensure that there are no special functional requirements and that the number of openings is strictly controlled. When there are no special functional requirements, the design of the casing of the strand-breaking robot should prioritize a fully sealed structure; If an opening is required, choose a circular hole to achieve the best electromagnetic shielding performance; Therefore, only circular openings are made on the enclosure for connecting internal and external data cables and control cables; In actual operation, considering that the robot body needs to rotate, the two sides of the body are designed separately, with the right side of the left body and the left side of the right body designed as openable and closable covers. The left and right boxes are connected by a rotating connecting assembly at the top to allow for opening and closing. The left side of the housing is provided with stepped buckles below the front surface and above the rear surface, and the right side of the housing is provided with step-like buckles above the front surface and below the rear surface. The left box body has stepped grooves above the front surface and below the rear surface, and the right box body has stepped grooves below the front surface and above the rear surface, corresponding to the shape of the stepped buckle. When the left and right boxes are closed, the step buckle and the step groove are completely engaged, and the left and right boxes form a sealed structure. A magnetic sealing strip is provided at the opening and closing joint between the left and right boxes; The casing of the strand-breaking robot also includes a conductive pad mounting groove located at the connection between the casing cover and other surfaces of the casing, with the conductive pad installed in the conductive pad mounting groove.

[0009] S2 includes: S2.1, Electrical shielding design for the enclosure; S2.2, Calculate the electric field shielding effectiveness; S2.3, The enclosure is designed with magnetic shielding.

[0010] S2.1 is as follows: When a hollow box is placed in an electric field of intensity E, it is affected by the external electric field, causing a redistribution of internal charges and the formation of a new electric field. If the robot box is considered as a seamless cube, its surface will be induced with charges. q As shown in the following formula: (1); In equation (1), a Indicates the length of the box.b This indicates the width of the enclosure, and the electrical conductivity of the enclosure material is... , E Indicates the electric field strength. Represents the vacuum permittivity; Based on the change in the external electric field, the charge is redistributed as follows: (2); In equation (2), The angular frequency that represents the change in electric field. A complex exponential function, representing the electric field changing with time at frequency. oscillation; Differentiating equation (2) with respect to time yields: (3); In equation (3), This represents the total current flowing through the edges of the enclosure.

[0011] In S2.2, the electric field shielding effectiveness is calculated as follows: Take a thickness of [value] on the shielding body. d The height is y Calculate the resistance of the circular ring: (4); In equation (4), The electrical conductivity of the enclosure material. a Indicates the length of the box. b Indicates the width of the box. d Indicates the thickness of the ring. y The height of the ring; Due to the long actual situation a Hekuan b Much greater than thickness d Simplify it to: ; Therefore, the voltage drop across the loop is: (5); In equation (5), Let be the voltage across the ring along the y-direction. This is the equivalent impedance of the ring; When unshielded, the external electric field strength is: ; Further calculations are needed to determine the electric field strength inside the enclosure, specifically the electric field strength inside the shielded enclosure: (6); The electric field shielding effectiveness can be calculated using the above formula: (7); In equation (7), Indicates the electric field shielding effectiveness. This represents the electric field strength measured by the device under test when no shielding measures are taken. This indicates the electric field strength measured by the device under test when shielding measures are taken.

[0012] S2.3 is as follows: The box is located in a magnetic field with a strength of B In a uniform magnetic field, the magnetic field strength inside the box is The enclosure is located below the power transmission lines; The formula for deriving parallel reluctance circuits is derived using parallel reluctance circuits. A parallel reluctance circuit includes: treating the magnetic reluctance within the enclosure as... R p The magnetic resistance of the shield is considered as R i , R p and R i in parallel, For flowing through R p and R i Total magnetic flux; Flowing through R p and R i The total magnetic flux, the magnetic flux flowing through the enclosure, and the magnetic flux flowing through the shield are respectively: (8); (9); (10); In equations (8), (9), and (10), Indicates flow through Rp and Ri The total magnetic flux, This represents the total magnetic flux flowing through the box. This represents the magnetic flux flowing through the shield. Represents the magnetic permeability in a vacuum. This represents the magnetic permeability of the shielding material. a Indicates the length of the box. b Indicates the width of the box. d The thickness of the ring, Indicates the external magnetic field strength. Indicates the magnetic flux density of the enclosure. Indicates the magnetic flux density of the shielding body; Located at the midpoint of the top surface of the enclosure, it is used to provide a reference value for the maximum magnetic flux density outside the enclosure; Located at the midpoint of the bottom surface of the box, and The comparison reveals the attenuation trend of the magnetic field along the height of the box; Located at the lower left corner of the top surface of the enclosure, it is used to provide the maximum residual magnetic flux density inside the enclosure; Located at the lower left corner of the top surface of the enclosure, it is used to provide the minimum residual magnetic flux density inside the enclosure; from arrive The magnetic reluctance is calculated using the following formula: (11); In equation (11), From arrive Magnetic reluctance; a represents the length of the housing; b represents the width of the housing; d represents the thickness of the annulus. Indicates the relative permeability of the enclosure material; from arrive The magnetic voltage drop is calculated using the following formula: (12); In equation (12), For the magnetic flux flowing through the shield, For the reluctance from P1 to Q1, This indicates the magnetic flux density of the shielding material. b Indicates the width of the box; from arrive The magnetic reluctance is calculated using the following formula: (13); In equation (13), For the reluctance from Q1 to Q2, a Indicates the length of the box. d The thickness of the ring, c Indicates the height of the box; from arrive The magnetic voltage drop is calculated using the following formula: (14); In equation (14), For the magnetic flux flowing through the shield, For the reluctance from Q1 to Q2, This indicates the magnetic flux density of the shielding material. c Indicates the height of the box; In summary, the magnetic voltage drop across the shield can be calculated: (15); Magnetic reluctance and magnetic voltage drop inside the enclosure: (16); (17); Equations (16) and (17), in The magnetic reluctance inside the box. The magnetic flux flowing through the box, c represents the magnetic flux density of the enclosure; c represents the height of the enclosure. Since the magnetic voltage drop inside the enclosure is equal to the magnetic voltage drop on the shield, we get: (18); (19); Since the sum of the magnetic flux flowing through the shield and the magnetic flux flowing through the box is the total magnetic flux, we can obtain: (20); Magnetic field shielding effectiveness represents the shielding capability of a shielding body, and its expression is: (twenty one); Electromagnetic shielding technology is used to achieve magnetic field attenuation that is greater than or equal to the minimum required shielding effectiveness.

[0013] In S3 Select shielding materials with high electrical conductivity and high magnetic permeability; In electromagnetic shielding design, the materials also need to be coated, which improves the efficiency and convenience of electromagnetic shielding.

[0014] S4 includes: S4.1 Based on the enclosure structure design of S1, a non-permanent joint shielding method is selected for the joint between the cover plate and other surfaces of the enclosure for gap shielding treatment, and the total gap shielding effectiveness is calculated. S4.2 After the gap shielding treatment is carried out at the joint between the cover plate and other surfaces of the enclosure, a conductive gasket is added at the joint of the cover plate to take into account that the opening and closing of the cover plate will cause electromagnetic leakage at the joint.

[0015] In S4.1, the overall shielding effectiveness of the gap is calculated as follows: The formula for calculating the reflection loss at the slit opening is as follows: (twenty two); In equation (22), N This is the ratio of the wave impedance at the slit opening to the wave impedance of the incident wave in space. N The value of is related to the incident field; When the incident field is a low impedance field: (twenty three); When the incident field is a plane wave field: (twenty four); In equation (24), r The distance between the shield and the field source. g The length of the gap. f For frequency; Transmission loss in the gap: (25); In equation (25), t The depth of the gap; The total shielding effectiveness of the gap is calculated from equations (22) and (25) as follows: (26); In equation (26), This indicates the overall shielding effectiveness of the gap.

[0016] The electromagnetic shielding design method for the double-body sealed enclosure of this strand-breaking robot also includes S5, which simulates the electromagnetic shielding effect of the strand-breaking robot, obtains the electric field strength and magnetic induction intensity inside the enclosure after shielding treatment, and compares them with the specified electromagnetic field strength requirements for exposure to the public to determine whether the design is compliant.

[0017] The main beneficial effects of this invention are as follows: 1) Excellent shielding performance, precise and reliable protection: This invention achieves precise protection with electric and magnetic shielding through a systematic design that combines high-conductivity, high-magnetic-permeability permalloy materials and a coating process. This results in an electric field shielding effectiveness of ≥33.3dB and a magnetic field shielding effectiveness of ≥18.85dB, ensuring that the electric field strength inside the enclosure is ≤4kV / m and the magnetic induction intensity is ≤0.1mT. This fully complies with the limits for public exposure to electromagnetic field strength, effectively blocking strong electromagnetic interference generated by high-voltage transmission lines and ensuring the stable operation of internal electrical components.

[0018] 2) Scientific structural design, taking into account practical needs: Adopting a fully sealed dual-body structure, the number of circular openings is strictly controlled, which reduces electromagnetic leakage channels while meeting the connection requirements of data lines and control lines. The openable cover design, combined with the installation of conductive gaskets, ensures electromagnetic shielding performance while providing convenience for equipment installation and maintenance, resolving the contradiction between sealing protection and operational flexibility. At the same time, the fully sealed structure can also effectively resist the effects of natural environments such as rain and corrosion, extending the service life of components.

[0019] 3) Strong compatibility between materials and processes, improving shielding efficiency: Permalloy was specifically selected as the core shielding material. Its high magnetic permeability can create a low magnetic reluctance path, significantly enhancing the magnetic field attenuation effect and improving the shielding effectiveness compared to traditional metal enclosures. The coating process further optimizes the material's conductivity. Combined with the dual protection process of non-permanent seam shielding and conductive gaskets, it effectively seals electromagnetic leakage from gaps, balancing shielding effectiveness with ease of later maintenance.

[0020] 4) The design process is standardized and highly verifiable: A complete shielding effectiveness calculation model was established, covering quantitative calculation methods for electric fields, magnetic fields, and gap shielding. At the same time, the shielding effect was visualized and verified through electromagnetic simulation, which can accurately predict the compliance of the design and avoid performance deficiencies or cost waste caused by blind design. This provides a systematic technical guarantee for the reliable operation of the strand-breaking robot in complex electromagnetic environments. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a front view of the box structure model of the present invention; Figure 2 This invention relates to a hollow box-shaped electric field shielding body. Figure 3 This invention relates to a hollow box-shaped magnetic field shielding body. Figure 4 This is the parallel reluctance circuit of the present invention; Figure 5 This is a partial view of the conductive pad mounting groove of the present invention; Figure 6 This is a three-dimensional positional diagram of the inner plane of the box of the present invention; Figure 7 This is a planar electric field diagram inside the box of the present invention; Figures 8(a), 8(b), and 8(c) show the three-dimensional magnetic field boundary condition settings of the present invention; Figure 9 This is a diagram of the magnetic field strength in the plane inside the box of the present invention.

[0022] In the diagram: 1. Circular opening; 2. Left side box; 3. Right side box; 4. Cover plate; 5. Rotary connecting assembly; 6. Stepped buckle; 7. Conductive pad mounting groove. Detailed Implementation

[0023] Example 1: An electromagnetic shielding design method for a dual-body sealed chassis of a strand-breaking robot, comprising the following steps: S1. Based on the electromagnetic shielding effect, the structure of the box of the strand-breaking robot is designed; S2, Electromagnetic shielding design for the casing of the strand-breaking robot; S3, Select the shielding material for the casing of the strand-breaking robot; S4. Considering both the structure and material of the strand-breaking robot housing, electromagnetic shielding design is implemented for the holes and gaps in the strand-breaking robot housing.

[0024] In S1, the design of the strand-breaking robot's housing includes: Only circular openings 1 are made on the box body for connecting the data lines and control lines that exist inside and outside. The box body of the strand-breaking robot is divided into two independent boxes, left and right. The right side of the left box body 2 and the left side of the right box body 3 are designed as openable and closable covers 4. The left box 2 and the right box 3 are connected by a rotating connecting assembly 5 at the top to open and close. The left box 2 is provided with stepped buckles below the front surface and above the rear surface, and the right box 3 is provided with stepped buckles below the front surface and below the rear surface. The left box 2 has stepped grooves above the front surface and below the rear surface, and the right box 3 has stepped grooves below the front surface and above the rear surface, corresponding to the shape of the stepped buckle 6. When the left and right boxes are closed, the step buckle 6 and the step groove are fully engaged, and the left and right boxes form a sealed structure. A magnetic sealing strip is provided at the opening and closing joint between the left box 2 and the right box 3; The structural model of the box-shaped body of the strand-breaking robot is as follows: Figure 1 As shown, considering the structural shielding design for the robot and the fact that there are connecting data and control lines inside and outside the box in practical applications, it is necessary to make openings in the box. Circular openings are chosen to minimize magnetic leakage and protect the electrical components inside the box. The box is split into a left box and a right box along the rotation axis. The right side of the left box and the left side of the right box are designed as openable covers, which facilitates installation and maintenance while preventing damage to the internal components from being exposed to a strong electromagnetic environment during rotation. The casing of the strand-breaking robot also includes a conductive pad mounting groove 7 located at the connection between the casing cover and other surfaces of the casing, and the conductive pad is installed in the conductive pad mounting groove 7.

[0025] After shielding the joints between the cover plate and other surfaces of the enclosure, to prevent electromagnetic leakage at the joints caused by the opening and closing of the cover plate, conductive gaskets are added. These gaskets are made of rubber with a copper overlay, combining the sealing performance of the rubber with the shielding effect of the copper layer to provide comprehensive electromagnetic interference protection for the equipment. A partial view of the conductive gasket mounting groove is shown below. Figure 5 As shown.

[0026] S2 includes: S2.1, Electrical shielding design for the casing of the strand-breaking robot; S2.2, Calculate the electric field shielding effectiveness; S2.3, Magnetic shielding design for the casing of the strand-breaking robot.

[0027] S2.1 is as follows: The box model of the stock cutting robot is as follows Figure 2 As shown, in an electric field environment with an electric field strength of E, the hollow box is affected by the external electric field, and the internal charges are redistributed to form a new electric field. The robot box is considered as a seamless cube with a length of a = 56 cm, a width of b = 29 cm, a height of c = 25 cm, and a wall thickness of d = 2 mm. The electrical conductivity of the box material is... The electric field strength at which it is located is E; Its surface induced charge q As shown in the following formula: (1); In equation (1), a Indicates the length of the box. b This indicates the width of the enclosure, and the electrical conductivity of the enclosure material is... , E Indicates the electric field strength. Represents the vacuum permittivity; Based on the change in the external electric field, the charge is redistributed as follows: (2); In equation (2), The angular frequency that represents the change in electric field. A complex exponential function, representing the electric field changing with time at frequency. oscillation; Differentiating equation (2) with respect to time yields: (3); In equation (3), This represents the total current flowing through the edges of the enclosure.

[0028] In S2.2, the electric field shielding effectiveness is calculated as follows: Take a thickness of [value] on the shielding body. d The height is y Calculate the resistance of the circular ring: (4); In equation (4), The electrical conductivity of the casing material for the strand-breaking robot. a Indicates the length of the box. b Indicates the width of the box. d Indicates the thickness of the ring. y The height of the ring; Due to the long actual situation a Hekuan b Much greater than thicknessd Simplify it to: ; Therefore, the voltage drop across the loop is: (5); In equation (5), Let be the voltage across the ring along the y-direction. This is the equivalent impedance of the ring; When unshielded, the external electric field strength is: ; Further calculations are needed to determine the electric field strength inside the enclosure, specifically the electric field strength inside the shielded enclosure: (6); The electric field shielding effectiveness can be calculated using the above formula: (7); In equation (7), Indicates the electric field shielding effectiveness. This represents the electric field strength measured by the device under test when no shielding measures are taken. This indicates the electric field strength measured by the device under test when shielding measures are taken.

[0029] The strand-breaking robot enclosure was deployed 50cm directly below a 110kV transmission line with three-phase conductors arranged in an inverted triangle. The measured peak electric field strength was... E 0 =184.45kV / m, which needs to meet the public exposure limit of 4kV / m, corresponding to the shielding effectiveness requirement. SE ≥33.3dB.

[0030] S2.3 is as follows: Magnetic field diagram as follows Figure 3 As shown, the box is located in a magnetic field with a strength of B In a uniform magnetic field, the magnetic field strength inside the box is The enclosure is located below the power transmission lines; The formula for parallel reluctance circuits is derived using parallel reluctance circuits. A parallel reluctance circuit is shown below. Figure 4 As shown, the parallel reluctance circuit includes: treating the reluctance inside the box as... R p The magnetic resistance of the shield is considered as R i , R p and R i in parallel, For flowing through R p and R i Total magnetic flux; Flowing through R p and R i The total magnetic flux, the magnetic flux flowing through the enclosure, and the magnetic flux flowing through the shield are respectively: (8); (9); (10); In equations (8), (9), and (10), Indicates flow through Rp and Ri The total magnetic flux, This represents the total magnetic flux flowing through the box. This represents the magnetic flux flowing through the shield. Represents the magnetic permeability in a vacuum. This represents the magnetic permeability of the shielding material. a Indicates the length of the box. b Indicates the width of the box. d The thickness of the ring, Indicates the external magnetic field strength. Indicates the magnetic flux density of the enclosure. Indicates the magnetic flux density of the shielding body; Located at the midpoint of the top surface of the enclosure, it is used to provide a reference value for the maximum magnetic flux density outside the enclosure; Located at the midpoint of the bottom surface of the box, and The comparison reveals the attenuation trend of the magnetic field along the height of the box; Located at the lower left corner of the top surface of the enclosure, it is used to provide the maximum residual magnetic flux density inside the enclosure; Located at the lower left corner of the top surface of the enclosure, it is used to provide the minimum residual magnetic flux density inside the enclosure; from arrive The magnetic reluctance is calculated using the following formula: (11); In equation (11), From arrive Magnetic reluctance; a represents the length of the housing; b represents the width of the housing; d represents the thickness of the annulus. Indicates the relative permeability of the enclosure material; from arrive The magnetic voltage drop is calculated using the following formula: (12); In equation (12), For the magnetic flux flowing through the shield, For the reluctance from P1 to Q1, This indicates the magnetic flux density of the shielding material. b Indicates the width of the box; from arrive The magnetic reluctance is calculated using the following formula: (13); In equation (13), For the reluctance from Q1 to Q2, a Indicates the length of the box. d The thickness of the ring, c Indicates the height of the box; from arrive The magnetic voltage drop is calculated using the following formula: (14); In equation (14), For the magnetic flux flowing through the shield, For the reluctance from Q1 to Q2, This indicates the magnetic flux density of the shielding material. c Indicates the height of the box; In summary, the magnetic voltage drop across the shield can be calculated: (15); Magnetic reluctance and magnetic voltage drop inside the enclosure: (16); (17); Equations (16) and (17), in The magnetic reluctance inside the box. The magnetic flux flowing through the box, c represents the magnetic flux density of the enclosure; c represents the height of the enclosure. Since the magnetic voltage drop inside the enclosure is equal to the magnetic voltage drop on the shield, we get: (18); (19); Since the sum of the magnetic flux flowing through the shield and the magnetic flux flowing through the box is the total magnetic flux, we can obtain: (20); Magnetic field shielding effectiveness represents the shielding capability of a shielding body, and its expression is: (twenty one); For a 110kV transmission line with three-phase conductors arranged in an inverted triangle, the power frequency magnetic field generated 50cm below the line... B 0=0.87562mT. To ensure that the magnetic field strength in the public exposure area meets the magnetic field strength limit of 0.1mT in the guidelines of the International Commission on Non-Ionizing Radiation Protection, the minimum shielding effectiveness required is calculated to be 18.85dB according to formula (21). Therefore, it is necessary to achieve a magnetic field attenuation of ≥18.85dB through electromagnetic shielding technology.

[0031] In S3, different conductive materials have different shielding performance. The magnetic field shielding performance is closely related to the conductivity and permeability of the material. As can be seen from Equations (7) and (21), the shielding effectiveness is proportional to the conductivity and permeability. Therefore, shielding materials with high conductivity and high permeability should be selected. The information table of common conductive materials is shown in Table 1.

[0032] Table 1. Conductivity and permeability of common conductive materials

[0033] Based on the analysis in the table above, permalloy was selected as the structural material for the box, with the material parameters set as follows: electrical conductivity 16000 S / m and magnetic permeability 20000 S / m. .

[0034] Step 3.2 In electromagnetic shielding design, when only a single layer of material needs to be treated, conductive spraying is the most commonly used diffusion coating technology. In addition, there are a variety of coating technologies available. See Table 2 for specific methods.

[0035] Table 2 Coating thickness and surface resistivity

[0036] Surface resistivity: ; In the formula: For electrical conductivity, This refers to the thickness of the shielding layer.

[0037] S4 includes: S4.1 Based on the enclosure structure design of S1, a non-permanent joint shielding method is selected for the joint between the cover plate and other surfaces of the enclosure for gap shielding treatment, and the total gap shielding effectiveness is calculated. S4.2 After the gap shielding treatment is carried out at the joint between the cover plate and other surfaces of the enclosure, a conductive gasket is added at the joint of the cover plate to take into account that the opening and closing of the cover plate will cause electromagnetic leakage at the joint.

[0038] In S4.1, the overall shielding effectiveness of the gap is calculated as follows: The formula for calculating the reflection loss at the slit opening is as follows: (twenty two); In equation (22), NThis is the ratio of the wave impedance at the slit opening to the wave impedance of the incident wave in space. N The value of is related to the incident field; When the incident field is a low impedance field: (twenty three); When the incident field is a plane wave field: (twenty four); In equation (24), r The distance between the shield and the field source. g The length of the gap. f For frequency; Transmission loss in the gap: (25); In equation (25), t The depth of the gap; The total shielding effectiveness of the gap is calculated from equations (22) and (25) as follows: (26); In equation (26), Indicates the overall shielding effectiveness of the gap; According to the shielding effectiveness formula, the shielding effectiveness of non-permanent joint treatment is relatively low. However, considering that non-permanent joints are more flexible and convenient for later operation and maintenance, non-permanent joint shielding is selected.

[0039] The electromagnetic shielding design method for the double-body sealed enclosure of this strand-breaking robot also includes S5, which simulates the electromagnetic shielding effect of the strand-breaking robot, obtains the electric field strength and magnetic induction intensity inside the enclosure after shielding treatment, and compares them with the specified electromagnetic field strength requirements for exposure to the public to determine whether the design is compliant.

[0040] In S5, the electromagnetic shielding effect of the strand-breaking robot is simulated. The specific steps are as follows: S5.1, the electromagnetically shielded box is considered to be made of only permalloy. The box of the strand-breaking robot is a hollow rectangular seamless model. Focusing on the permalloy material itself, electromagnetic shielding simulation is performed on the model. S5.2, Simulation analysis of the electric field shielding of the enclosure; The solver is set to electrostatic field. A cubic air domain with a length, width and height of 1m is established. A parallel plate capacitor boundary is constructed using a cuboid of the same size. The plates are ideal conductors. The boundary polarization effect is ignored. The potential of the upper parallel plane is set to the external electric field strength of the box, which is 184.45KV / m, and the potential of the lower parallel plane is set to 0KV / m.

[0041] Since the hollow cuboid is symmetric about the three coordinate planes, the three-phase conductors have a 120° phase difference, the excitation field is symmetric about the x=0 and y=0 planes, and the electric field of the parallel plate capacitor is uniformly distributed along the negative z-axis, and the excitation field is symmetric about the x=0 and y=0 planes, the first octet can be retained as the computational domain, and symmetric boundary conditions can be applied to the other three symmetric planes respectively. Even boundary conditions are added where the electric field lines are parallel to the boundaries and no electric flux passes through the boundaries.

[0042] The hollow box model is imported into the simulation software, material parameters are set, and an xoy plane is created inside the box. The plane is positioned as follows: Figure 6 As shown.

[0043] The electric field diagram of the internal planar model of the box is shown in the figure below. Figure 7 As shown.

[0044] Based on the electric field distribution cloud map and intensity quantification data, it can be seen that the electric field intensity in the target plane area meets the safety protection requirements of power frequency electric field. The permalloy enclosure, through its high dielectric loss characteristics and surface charge skin effect, can achieve three-dimensional attenuation of electric field intensity from the surface to the interior of the enclosure. Its shielding effectiveness is 2.6 times higher than that of traditional metal enclosures, meeting the electric field protection requirements in complex electromagnetic environments.

[0045] S5.3, Simulation analysis of the magnetic field shielding of the enclosure; The low-frequency static magnetic field shielding effectiveness of the enclosure was analyzed. A model consistent with the electric field shielding design was adopted, and a static magnetic field solver was configured. A tangential magnetic field forced zero condition (TangentialHField=0) was applied to the top boundary to simulate the physical scenario of magnetic field lines being perpendicularly incident in infinite space. The lateral boundary adopted a zero tangential magnetic field boundary to avoid the influence of artificial boundary reflection error on the near-field distribution of the enclosure. The three-dimensional magnetic field boundary condition settings are shown in Figure 8.

[0046] After setting it up, a simulation is performed, and the induction intensity of the plane inside the box is as follows: Figure 9 As shown.

[0047] Based on the magnetic induction intensity cloud map and intensity quantification results, it can be seen that the peak magnetic induction intensity of the target plane region meets the safety protection requirements of power frequency magnetic field. The enclosure uses permalloy as the enclosure material, forming a low magnetic resistance path on the enclosure surface, which can effectively suppress the interference of external power frequency magnetic field on sensitive electronic equipment.

Claims

1. An electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot, characterized in that... Includes the following steps: S1. Based on the electromagnetic shielding effect, the structure of the box of the strand-breaking robot is designed; S2, Electromagnetic shielding design for the casing of the strand-breaking robot; S3, Select the shielding material for the casing of the strand-breaking robot; S4. Considering both the structure and material of the strand-breaking robot housing, electromagnetic shielding design is implemented for the holes and gaps in the strand-breaking robot housing.

2. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 1, characterized in that: In S1, the design of the strand-breaking robot's housing includes: Only circular openings (1) are made on the box body for connecting the data lines and control lines that exist inside and outside. The box body of the strand-breaking robot is divided into two independent boxes, left and right. The right side of the left box body (2) and the left side of the right box body (3) are designed as openable covers (4). The left box (2) and the right box (3) are connected by a rotating connection assembly (5) at the top to open and close. The left box (2) is provided with stepped buckles (6) below the front surface and above the rear surface, and the right box (3) is provided with stepped buckles (6) above the front surface and below the rear surface. The left box (2) has stepped grooves above the front surface and below the rear surface, and the right box (3) has stepped grooves below the front surface and above the rear surface that correspond to the shape of the stepped buckle (6). When the left and right boxes are closed, the step buckle (6) and the step groove are completely engaged, and the left and right boxes form a sealed structure. A magnetic sealing strip is provided at the opening and closing joint between the left box (2) and the right box (3); The casing of the strand-breaking robot also includes a conductive pad mounting groove (7) located at the connection between the casing cover and other surfaces of the casing, and the conductive pad is installed in the conductive pad mounting groove (7).

3. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 1, characterized in that: S2 includes: S2.1, Electrical shielding design for the enclosure; S2.2, Calculate the electric field shielding effectiveness; S2.3, The enclosure is designed with magnetic shielding.

4. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 3, characterized in that: S2.1 is as follows: When a hollow box is placed in an electric field of intensity E, it is affected by the external electric field, causing a redistribution of internal charges and the formation of a new electric field. If the robot box is considered as a seamless cube, its surface will be induced with charges. q As shown in the following formula: （1）； In equation (1), a Indicates the length of the box. b This indicates the width of the enclosure, and the electrical conductivity of the enclosure material is... , E Indicates the electric field strength. Represents the vacuum permittivity; Based on the change in the external electric field, the charge is redistributed as follows: （2）； In equation (2), The angular frequency that represents the change in electric field. A complex exponential function, representing the electric field changing with time at frequency. oscillation; Differentiating equation (2) with respect to time yields: （3）； In equation (3), This represents the total current flowing through the edges of the enclosure.

5. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 4, characterized in that: In S2.2, the electric field shielding effectiveness is calculated as follows: Take a thickness of [value] on the shielding body. d The height is y Calculate the resistance of the circular ring: （4）； In equation (4), The electrical conductivity of the enclosure material. a Indicates the length of the box. b Indicates the width of the box. d Indicates the thickness of the ring. y The height of the ring; Therefore, the voltage drop across the loop is: （5）； In equation (5), Let be the voltage across the ring along the y-direction. This is the equivalent impedance of the ring; Further calculations of the electric field strength inside the enclosure: （6）； The electric field shielding effectiveness can be calculated using the above formula: （7）； In equation (7), Indicates the electric field shielding effectiveness. This represents the electric field strength measured by the device under test when no shielding measures are taken. This indicates the electric field strength measured by the device under test when shielding measures are taken.

6. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 5, characterized in that: S2.3 is as follows: The box is located in a magnetic field with a strength of B In a uniform magnetic field, the magnetic field strength inside the box is The enclosure is located below the power transmission lines; The formula for deriving parallel reluctance circuits is derived using parallel reluctance circuits. A parallel reluctance circuit includes: treating the magnetic reluctance within the enclosure as... R p The magnetic resistance of the shield is considered as R i , R p and R i in parallel, For flowing through R p and R i Total magnetic flux; Flowing through R p and R i The total magnetic flux, the magnetic flux flowing through the enclosure, and the magnetic flux flowing through the shield are respectively: （8）； （9）； （10）； In equations (8), (9), and (10), Indicates flow through Rp and Ri The total magnetic flux, This represents the total magnetic flux flowing through the box. This represents the magnetic flux flowing through the shield. Represents the magnetic permeability in a vacuum. This represents the magnetic permeability of the shielding material. a Indicates the length of the box. b Indicates the width of the box. d The thickness of the ring, Indicates the external magnetic field strength. Indicates the magnetic flux density of the enclosure. Indicates the magnetic flux density of the shielding body; Located at the midpoint of the top surface of the enclosure, it is used to provide a reference value for the maximum magnetic flux density outside the enclosure; Located at the midpoint of the bottom surface of the box, and The comparison reveals the attenuation trend of the magnetic field along the height of the box; Located at the lower left corner of the top surface of the enclosure, it is used to provide the maximum residual magnetic flux density inside the enclosure; Located at the lower left corner of the top surface of the enclosure, it is used to provide the minimum residual magnetic flux density inside the enclosure; from arrive The magnetic reluctance is calculated using the following formula: （11）； In equation (11), From arrive Magnetic reluctance; a represents the length of the housing; b represents the width of the housing; d represents the thickness of the annulus. Indicates the relative permeability of the enclosure material; from arrive The magnetic voltage drop is calculated using the following formula: （12）； In equation (12), For the magnetic flux flowing through the shield, For the reluctance from P1 to Q1, This indicates the magnetic flux density of the shielding material. b Indicates the width of the box; from arrive The magnetic reluctance is calculated using the following formula: （13）； In equation (13), For the reluctance from Q1 to Q2, a Indicates the length of the box. d The thickness of the ring, c Indicates the height of the box; from arrive The magnetic voltage drop is calculated using the following formula: （14）； In equation (14), For the magnetic flux flowing through the shield, For the reluctance from Q1 to Q2, This indicates the magnetic flux density of the shielding material. c Indicates the height of the box; In summary, the magnetic voltage drop across the shield can be calculated: （15）； Magnetic reluctance and magnetic voltage drop inside the enclosure: （16）； （17）； Equations (16) and (17), in The magnetic reluctance inside the box. The magnetic flux flowing through the box, c represents the magnetic flux density of the enclosure; c represents the height of the enclosure. Since the magnetic voltage drop inside the enclosure is equal to the magnetic voltage drop on the shield, we get: （18）； （19）； Since the sum of the magnetic flux flowing through the shield and the magnetic flux flowing through the box is the total magnetic flux, we can obtain: （20）； Magnetic field shielding effectiveness represents the shielding capability of a shielding body, and its expression is: （21）； Electromagnetic shielding technology is used to achieve magnetic field attenuation that is greater than or equal to the minimum required shielding effectiveness.

7. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 1, characterized in that: In S3 Select shielding materials with high electrical conductivity and high magnetic permeability; In electromagnetic shielding design, the materials also need to be coated, which improves the efficiency and convenience of electromagnetic shielding.

8. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 1, characterized in that: S4 includes: S4.1 Based on the enclosure structure design of S1, a non-permanent joint shielding method is selected for the joint between the cover plate and other surfaces of the enclosure for gap shielding treatment, and the total gap shielding effectiveness is calculated. S4.2 After the gap shielding treatment is carried out at the joint between the cover plate and other surfaces of the enclosure, a conductive gasket is added at the joint of the cover plate to take into account that the opening and closing of the cover plate will cause electromagnetic leakage at the joint.

9. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 8, characterized in that: In S4.1, the overall shielding effectiveness of the gap is calculated as follows: The formula for calculating the reflection loss at the slit opening is as follows: （22）； In equation (22), N This is the ratio of the wave impedance at the slit opening to the wave impedance of the incident wave in space. N The value of is related to the incident field; When the incident field is a low impedance field: （23）； When the incident field is a plane wave field: （24）； In equation (24), r The distance between the shield and the field source. g The length of the gap. f For frequency; Transmission loss in the gap: （25）； In equation (25), t The depth of the gap; The total shielding effectiveness of the gap is calculated from equations (22) and (25) as follows: （26）； In equation (26), This indicates the overall shielding effectiveness of the gap.

10. The electromagnetic shielding design method for a double-body sealed chassis of a strand-breaking robot according to claim 1, characterized in that: It also includes S5, which simulates the electromagnetic shielding effect of the strand-breaking robot, obtains the electric field strength and magnetic induction intensity inside the box after shielding treatment, and compares them with the specified electromagnetic field strength requirements for public exposure to determine whether the design is compliant.

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