Control device and control system for stay cable of long-span bridge

Abstract

The invention discloses a control device and a control system for a stay cable of a long-span bridge. The control device comprises an eddy current damping element, a ball screw transmission system, a first connecting piece and a second connecting piece. The ball screw transmission system converts relative axial movement generated at the two ends of the eddy current damping element into high-speed rotating movement of the conductor disc, the eddy current damping element generates a damping effect according to input current, the high-speed rotating movement of the conductor disc is hindered, the device can adapt to the working conditions that various vibration modes occur in the actual operation process of the long stay cable, and the service life of the long stay cable is prolonged. And the vibration response of the long stay cable is effectively inhibited. The invention further discloses a control system of the large-span bridge stay cable, the input current of the eddy current damping element can be adjusted in real time according to the order of the vibration mode generated by the stay cable, so that for each order of vibration mode of the stay cable, the damping coefficient of the eddy current damping element can be close to the optimal damping coefficient of the vibration mode, and the damping coefficient of the eddy current damping element is close to the optimal damping coefficient of the vibration mode. And real-time optimal control is realized.

Description

Technical Field

[0001] The present application relates to the field of long-span bridge stay cables, and in particular to a control device and a control system for long-span bridge stay cables. Background Art

[0002] The cable is the main load-bearing component that directly transfers the weight of the main beam and bridge deck of the cable-stayed bridge to the tower. The main reasons for the vibration of the cable include vortex-induced resonance, wind-rain induced vibration, parameter induced vibration, wake galloping vibration, rain vibration, etc. These vibrations not only damage the cable itself, but also may affect the overall stability and safety of the bridge.

[0003] At present, permanent magnet eddy current dampers are mainly used for cable-stayed cables of large-span bridges. The damping coefficient of the permanent magnet eddy current damper cannot be adjusted in real time and can only be used as a passive control device, which has a poor effect in suppressing the vibration of the cable. Summary of the invention

[0004] In view of this, the present application provides a control device and control system for a large-span bridge cable, aiming to improve the control effect of the multi-modal vibration of the cable, effectively suppress the vibration response of the long cable, and extend the service life of the cable.

[0005] In a first aspect, the present application provides a control device for a long-span bridge cable, characterized in that the device comprises: an eddy current damping element, a ball screw transmission system, a first connecting member and a second connecting member; the eddy current damping element comprises a conductor disk;

[0006] One end of the first connecting member is connected to the inclined cable, and the other end of the first connecting member is connected to the eddy current damping element;

[0007] One end of the second connecting member is connected to the eddy current damping element, and the other end of the second connecting member is connected to the bridge deck supporting structure;

[0008] Two ends of the ball screw transmission system are respectively connected to the first connecting member and the second connecting member;

[0009] The ball screw transmission system is used to convert the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disk, so that the eddy current damping element generates a damping force;

[0010] The eddy current damping element is used to generate a damping effect according to the input current, hinder the high-speed rotation of the conductor disk, and dissipate the energy generated by the vibration of the inclined cable.

[0011] Optionally, the eddy current damping element further comprises: a first back iron, a second back iron and an energized spiral coil fixed between the first back iron and the second back iron;

[0012] The energized spiral coil comprises an upper energized spiral coil, a lower energized spiral coil and the conductor disk, wherein the conductor disk is arranged between the upper energized spiral coil and the lower energized spiral coil;

[0013] The first back iron and the second back iron are respectively used to fix the energized spiral coil;

[0014] The energized spiral coil is used to generate a magnetic field that varies with the magnitude of the current after being energized;

[0015] The conductor disk is used to cut magnetic lines of force in the magnetic field to generate induced eddy currents. The induced eddy currents interact with the magnetic field generated by the energized spiral coil to generate a Lorentz force that hinders the relative movement between the conductor disk and the energized spiral coil, so as to dissipate the energy generated by the vibration of the inclined cable.

[0016] Optionally, the spiral coils at corresponding positions of the upper powered spiral coil and the lower powered spiral coil have the same magnetization direction, the current directions between adjacent upper powered spiral coils and the lower powered spiral coils are opposite, and the magnetic poles are arranged in an alternating positive and negative manner;

[0017] The upper energized spiral coil comprises: a first upper energized spiral coil, a second upper energized spiral coil, a third upper energized spiral coil and a fourth upper energized spiral coil;

[0018] The lower powered spiral coil includes: a first lower powered spiral coil, a second lower powered spiral coil, a third lower powered spiral coil and a fourth lower powered spiral coil.

[0019] Optionally, the ball screw transmission system comprises a ball screw and a nut, the ball screw comprises a ball; the nut has a guide groove inside that matches the ball;

[0020] The eddy current damping element is installed in the middle of the ball screw, has the same axis as the ball screw, and is connected to the nut;

[0021] When the force generated by the axial movement is transmitted to one end of the ball screw and the nut respectively, the balls roll on the guide grooves, and the axial movement is converted into the rotational movement of the nut through the rolling.

[0022] Optionally, the control device further comprises a housing, the housing comprising an upper circular surface, a lower circular surface and a cylindrical side surface between the upper circular surface and the lower circular surface, the upper circular surface is connected to the first back iron, and the lower circular surface is connected to the second back iron;

[0023] The housing is used to protect the eddy current damping element.

[0024] Optionally, the first back-iron and the second back-iron are made of high magnetic permeability materials.

[0025] Optionally, the conductor disk is made of a non-ferromagnetic material with high electrical conductivity.

[0026] In a second aspect, the present application provides a control system for a long-span bridge cable, the system comprising a signal acquisition module, a calculation and analysis module and a damping force output module, the damping force output module comprising the control device as described in the first aspect;

[0027] The signal acquisition module is used to collect the vibration response signal of the cable and send it to the calculation and analysis module;

[0028] The calculation and analysis module is used to calculate the optimal input current of the control device according to the vibration response signal using a preset algorithm;

[0029] The damping force output module is used to transmit the optimal input current to the control device, so that the control device outputs the damping force of the eddy current damping element, and the damping force acts on the inclined cable.

[0030] Optionally, the computing and analyzing module is specifically used to:

[0031] According to the structural parameters of the cable, the optimal damping coefficient of each order vibration mode of the cable is calculated by using the relationship between the additional modal damping ratio and the damping coefficient of the viscous damper;

[0032] Calculating and analyzing the vibration response of the cable obtained by the signal acquisition module to obtain the real-time vibration mode of the cable and the optimal damping coefficient of the cable under the real-time vibration mode;

[0033] Establishing an equivalent damping coefficient expression of the eddy current damping element;

[0034] Calculating the equivalent damping coefficient of the eddy current damping element under different currents;

[0035] According to the optimal damping coefficient and the equivalent damping coefficient, the optimal input current of the eddy current damping element is obtained.

[0036] Optionally, the damping force output module is specifically used to:

[0037] According to the optimal input current and the vibration response signal of the inclined cable, the control device outputs the damping force of the eddy current damping element, which acts on the inclined cable through the first connecting member.

[0038] The above technical solution has the following beneficial effects:

[0039] The present application provides a control device and control system for a long-span bridge cable. The control device includes an eddy current damping element, a ball screw transmission system, a first connector and a second connector; the eddy current damping element includes a conductor disc; one end of the first connector is connected to the cable, and the other end of the first connector is connected to the eddy current damping element; one end of the second connector is connected to the eddy current damping element, and the other end of the second connector is connected to the bridge deck support structure; the two ends of the ball screw transmission system are respectively connected to the first connector and the second connector; the ball screw transmission system is used to convert the relative axial motion generated by the two ends of the eddy current damping element into the high-speed rotation motion of the conductor disc, so that the eddy current damping element generates a damping force; the eddy current damping element is used to generate a damping effect according to the input current, hinder the high-speed rotation motion of the conductor disc, so as to dissipate the energy generated by the vibration of the cable. The ball screw transmission system in the present application converts the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disc, so that the eddy current damping element generates a damping force. The eddy current damping element generates a damping effect according to the input current, hinders the high-speed rotational motion of the conductor disc, and dissipates the energy generated by the vibration of the cable. The input current of the semi-active control device can be adjusted in real time according to the vibration mode order occurring during the actual operation of the long cable, so as to adapt to the working conditions of various vibration modes of the long cable, realize real-time optimal control, greatly improve the control effect of the multi-modal vibration of the cable, effectively suppress the vibration response of the long cable, extend the service life of the cable, and avoid affecting the operation of the bridge and endangering the safety of the bridge due to its fatigue failure.

[0040] The present application also provides a control system for a large-span bridge cable, the system comprising a signal acquisition module, a calculation and analysis module and a damping force output module, the damping force output module comprising a control device, the control system being able to adjust the input current of the eddy current damping element in real time according to the order of the vibration mode of the cable, so that for each order of vibration mode of the cable, the damping coefficient of the eddy current damping element can be near the optimal damping coefficient of the vibration mode, thereby achieving real-time optimal control. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of a structure of a control device for a long-span bridge cable provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of a finite element simulation model of an eddy current damping element provided in an embodiment of the present application;

[0044] Figure 3 A schematic diagram of the grid division and current direction of the eddy current damping element provided in an embodiment of the present application;

[0045] Figure 4 A diagram showing the finite element simulation results of the eddy current damping element provided in an embodiment of the present application;

[0046] Figure 5 A schematic structural diagram of a control system for a long-span bridge cable-stayed cable provided in an embodiment of the present application;

[0047] Figure 6 A schematic diagram of a workflow of a control system provided in an embodiment of the present application.

[0048] In the attached figure:

[0049] 1: first connecting piece, 2: ball screw, 3: first back iron, 4: first thrust bearing, 5: nut, 6: first upper energized spiral coil, 7: first iron core, 8: second upper energized spiral coil, 9: second iron core, 10: third upper energized spiral coil, 11: third iron core, 12: fourth upper energized spiral coil, 13: fourth iron core, 14: conductor disk, 15: first lower energized spiral coil, 16: fifth iron core, 17: second lower energized spiral coil, 18: sixth iron core, 19: third lower energized spiral coil, 20: seventh iron core, 21: fourth lower energized spiral coil, 22: eighth iron core, 23: housing, 24: second thrust bearing, 25: second back iron, 26: second connecting piece. DETAILED DESCRIPTION

[0050] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] In order to facilitate further understanding of the technical solution provided by this application, the background technology involved in this application will be explained below.

[0052] Installing external damper devices at the ends of the cable, such as viscous dampers (VD), magnetorheological dampers (MR) and eddy current dampers (ECD) and other passive control devices, is a common method to control various vibration forms of the cable. However, with the increase in the span of the bridge, the length of the cable increases, and its natural frequency decreases significantly. The range of wind-induced vibration modes that are prone to occur under normal wind speeds is wide, and for different vibration modes of the cable, the optimal damping coefficient corresponding to the maximum additional modal damping ratio will gradually decrease with the increase of the modal order. The damping coefficient of the passive damper has been set before installation and cannot be changed. Due to the limited installation height of the damper, it can only provide sufficient additional modal damping ratio for low-order modes, and the control performance of high-order vibration is very limited. Therefore, using passive dampers to suppress multi-modal vibration of long cable is challenging. In addition, the damping coefficient optimization of passive dampers is often designed for specific vibration modes, which leads to suboptimal control or uncontrollable control of other vibration modes. That is, the permanent magnet eddy current damper mainly used has a damping coefficient that cannot be adjusted in real time and can only be used as a passive control device.

[0053] In order to overcome the above-mentioned technical problems, the present application provides a control device for a long-span bridge cable, which includes an eddy current damping element, a ball screw transmission system, a first connecting member and a second connecting member; the eddy current damping element includes a conductor disk; one end of the first connecting member is connected to the cable, and the other end of the first connecting member is connected to the eddy current damping element; one end of the second connecting member is connected to the eddy current damping element, and the other end of the second connecting member is connected to the bridge deck support structure; the two ends of the ball screw transmission system are respectively connected to the first connecting member and the second connecting member; the ball screw transmission system is used to convert the relative axial movement generated at the two ends of the eddy current damping element into a high-speed rotational movement of the conductor disk, so that the eddy current damping element generates a damping force; the eddy current damping element is used to generate a damping effect according to the input current, hinder the high-speed rotational movement of the conductor disk, so as to dissipate the energy generated by the vibration of the cable. The ball screw transmission system in the present application converts the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disc, so that the eddy current damping element generates a damping force. The eddy current damping element generates a damping effect according to the input current, hinders the high-speed rotational motion of the conductor disc, and dissipates the energy generated by the vibration of the cable. It can adapt to the working conditions of various vibration modes of the long cable during actual operation, greatly improve the control effect of the multi-modal vibration of the cable, effectively suppress the vibration response of the long cable, extend the service life of the cable, and avoid affecting the operation of the bridge and endangering the safety of the bridge due to its fatigue failure.

[0054] See also Figure 1 , Figure 1 A schematic structural diagram of a control device for a long-span bridge cable provided in an embodiment of the present application.

[0055] The control device comprises: an eddy current damping element, a ball screw transmission system, a first connecting member 1 and a second connecting member 26; the eddy current damping element comprises a conductor disk 14;

[0056] One end of the first connecting member 1 is connected to the inclined cable (not shown in the figure), and the other end of the first connecting member 1 is connected to the eddy current damping element;

[0057] One end of the second connecting member 26 is connected to the eddy current damping element, and the other end of the second connecting member is connected to the bridge deck support structure (not shown in the figure);

[0058] Two ends of the ball screw transmission system are respectively connected to the first connecting member and the second connecting member;

[0059] The ball screw transmission system is used to convert the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disk, so that the eddy current damping element generates a damping force;

[0060] The eddy current damping element is used to generate a damping effect according to the input current, hinder the high-speed rotation of the conductor disk, and dissipate the energy generated by the vibration of the inclined cable.

[0061] Among them, the high-speed rotational motion is to make the eddy current damping element produce a greater damping force, thereby greatly improving the energy consumption efficiency of the eddy current damping element.

[0062] It can be understood that the vibration of the inclined cable can be converted into forces of equal magnitude and opposite direction and applied axially to the upper and lower connection points (1, 26) of the eddy current damping element, and relative axial movement will be generated between the two ends of the eddy current damping element. The ball screw transmission system converts the relative axial movement generated at the two ends of the eddy current damping element into the high-speed rotational movement of the conductor disk, so that the eddy current damping element generates a damping force; the eddy current damping element generates a damping effect according to the input current, hinders the high-speed rotational movement of the conductor disk, and dissipates the energy generated by the vibration of the inclined cable.

[0063] In the present application, the ball screw transmission system converts the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disc, so that the eddy current damping element generates a damping force. The eddy current damping element generates a damping effect according to the input current, hinders the high-speed rotational motion of the conductor disc, and dissipates the energy generated by the vibration of the cable. It can adapt to the working conditions of various vibration modes of the long cable during actual operation, greatly improve the control effect of the multi-modal vibration of the cable, effectively suppress the vibration response of the long cable, extend the service life of the cable, and avoid affecting the operation of the bridge and endangering the safety of the bridge due to its fatigue failure.

[0064] In one possible implementation, Figure 1 As shown, the eddy current damping element comprises: a first back iron 3, a second back iron 25 and an energized spiral coil fixed between the first back iron and the second back iron;

[0065] The energized spiral coil comprises an upper energized spiral coil (6, 8, 10 and 12), a lower energized spiral coil (15, 17, 19 and 21) and the conductor disk 14, wherein the conductor disk 14 is arranged between the upper energized spiral coil and the lower energized spiral coil;

[0066] The first back iron 3 and the second back iron 25 are respectively used to fix the energized spiral coil;

[0067] The energized spiral coil is used to generate a magnetic field that varies with the magnitude of the current after being energized;

[0068] The conductor disk 14 is used to cut magnetic lines of force in the magnetic field to generate induced eddy currents. The induced eddy currents interact with the magnetic field generated by the energized spiral coil to generate a Lorentz force that hinders the relative motion between the conductor disk and the energized spiral coil, so as to dissipate the energy generated by the vibration of the inclined cable.

[0069] It should be noted that the back iron can be made of a material with high magnetic permeability. In addition to having a magnetic conductivity function of increasing the magnetic flux density, it can also fix the iron core and the energized spiral coil.

[0070] The conductor disk is made of non-ferromagnetic material with high conductivity. Its function is: to cut magnetic lines of force in the magnetic field, generate induced eddy currents, and the eddy currents interact with the magnetic field generated by the energized coil to generate the Lorentz force (Lenz's theorem) that hinders the relative motion between the conductor disk and the energized coil. From the perspective of energy conservation, the mechanical energy of the conductor disk is first converted into electrical energy inside the conductor disk, and then finally converted into heat energy through the resistance of the conductor disk and dissipated, producing a damping effect.

[0071] It can be understood that according to Faraday's law of electromagnetic induction, an energized spiral coil will generate an induced magnetic field when energized. When the conductor moves in the magnetic field to cut the magnetic lines of force, the induced electromotive force in the conductor will generate eddy currents. The eddy currents generate a new induced magnetic field in a direction that hinders the relative motion of the conductor and the magnet, thereby forming a damping force.

[0072] In a possible implementation, the eddy current damping element also includes a first core 7, a second core 9, a third core 11, a fourth core 13, a fifth core 16, a sixth core 18, a seventh core 20 and an eighth core 22, wherein the cores are coaxial with the energized spiral coil and are used to enhance the magnetic field of the energized spiral coil.

[0073] In a possible implementation, the magnetization directions of the spiral coils at corresponding positions of the upper powered spiral coil and the lower powered spiral coil are the same, the current directions between the adjacent upper powered spiral coils and the lower powered spiral coils are opposite, and the magnetic poles are arranged in an alternating positive and negative manner;

[0074] like Figure 1 As shown, the upper powered spiral coil comprises: a first upper powered spiral coil 6, a second upper powered spiral coil 8, a third upper powered spiral coil 10 and a fourth upper powered spiral coil 12;

[0075] The lower powered helical coil comprises: a first lower powered helical coil 15 , a second lower powered helical coil 17 , a third lower powered helical coil 19 and a fourth lower powered helical coil 21 .

[0076] In one possible implementation, Figure 1 As shown, the ball screw transmission system includes a ball screw 2 and a nut 5, wherein the ball screw includes a ball; and the nut has a guide groove inside that matches the ball;

[0077] The eddy current damping element is installed in the middle of the ball screw, has the same axis as the ball screw, and is connected to the nut;

[0078] When the force generated by the axial movement is transmitted to one end of the ball screw and the nut respectively, the balls roll on the guide grooves, and the axial movement is converted into the rotational movement of the nut through the rolling.

[0079] It can be understood that in the present application, a certain number of balls are arranged on the ball screw, and there are guide grooves matching the balls inside the nut. When the force of axial movement is transmitted to one end of the ball screw and the nut respectively, the balls are forced to roll on the guide grooves between the ball screw and the nut. The balls transmit and convert force by rolling, thereby converting the axial movement into the rotational movement of the nut.

[0080] In a possible implementation, the ball screw transmission system further includes a first thrust bearing 4 and a second thrust bearing 24 .

[0081] Among them, the role of the thrust bearing is, on the one hand, to bear and transmit the axial load, and on the other hand, the two ends of the thrust bearing are respectively connected to the nut and the back iron. Because when the control device is working, the back iron is fixed and the nut is constantly rotating, so the role of the thrust bearing is required to greatly reduce the friction coefficient, so that the ball screw pair can rotate while transmitting the damping force without getting stuck.

[0082] In one possible implementation, Figure 1 As shown, the control device also includes a housing 23, which is coaxial with the ball screw (2).

[0083] The housing 23 includes an upper circular surface, a lower circular surface and a cylindrical side surface between the upper circular surface and the lower circular surface, the upper circular surface is connected to the first back iron, and the lower circular surface is connected to the second back iron;

[0084] The housing is used to protect the eddy current damping element.

[0085] In order to optimize the construction parameters of the eddy current damping element, it is simulated.

[0086] like Figure 2 , which is a schematic diagram of a finite element simulation model of an eddy current damping element provided in an embodiment of the present application.

[0087] S2. Define the eddy current damping element model size parameters in COMSOL Multiphysics simulation software.

[0088] S21. Because the ball screw has almost no effect on its damping performance, no simulation is required.

[0089] S22. Define the radius CDR and thickness CDH of the conductor disk (14).

[0090] S23. Define the radius SIR, height SIH, and number of turns CoilTurns of the spiral coil (6, 8, 10, 12, 15, 17, 19, 21).

[0091] S24. Define the radius TIR and height TIH of the core (7, 9, 11, 13, 16, 18, 20, 22).

[0092] S25. Define the radius BIR and thickness BIH of the first and second back irons (3, 25).

[0093] S26. Define the position of the first back iron (3): coaxial with the conductor disk (14), with a height of TIH+CDH / 2+BIH / 2; define the position of the second back iron (25): coaxial with the conductor disk 14, with a height of -(TIH+CDH / 2+BIH / 2).

[0094] S27. Define the air gap distance MagGap between the lower surface of the spiral coil (6, 8, 10, 12) and the upper surface of the conductor disk, and the air gap distance MagGap between the upper surface of the spiral coil (15, 17, 19, 21) and the lower surface of the conductor disk.

[0095] S28. Define the distance between the center of the spiral coil (6, 8, 10, 12, 15, 17, 19, 21) and the center of the conductor disk as SIP. Preferably, the spiral coils (6, 8, 10, 12) are arranged in a circular array and connected to the first back iron 3, and the spiral coils (15, 17, 19, 21) are arranged in a circular array and connected to the second back iron 25.

[0096] S29. Preferably, the iron core (7, 9, 11, 13, 16, 18, 20, 22) and the spiral coil (6, 8, 10, 12, 15, 17, 19, 21) are defined to be coaxial and have the same installation height.

[0097] S3. Establish the model geometry in COMSOL Multiphysics software.

[0098] S31. Preferably, the calculation domain is defined as a sphere with a radius of 3×CDR.

[0099] S32, assembling the components to form a union.

[0100] S4. Define material parameters in COMSOL Multiphysics software.

[0101] S41. The computational domain is defined as air, with a relative magnetic permeability of 1 and a relative permittivity of 1.

[0102] S42. Define that the conductor disk (14) and the spiral coil (6, 8, 10, 12, 15, 17, 19, 21) are made of copper, with a relative magnetic permeability of 1, an electrical conductivity of 5.998×107 [Siemens / meter], and a relative dielectric constant of 1.

[0103] S43. Define the first and second back iron (3, 25) materials as low carbon steel with a relative magnetic permeability of 4000 and a relative dielectric constant of 1.

[0104] S44. Define the material of the iron core (7, 9, 11, 13, 16, 18, 20, 22) as pure iron, with a relative magnetic permeability of 4000 and a relative dielectric constant of 1.

[0105] S5. Establish magnetic field and electric field analysis modules in COMSOL Multiphysics software.

[0106] S51. Set the current in the spiral coils (6, 8, 10, 12, 15, 17, 19, 21) to 0-3 [amperes]. Preferably, the directions of the currents in the spiral coils (6, 8, 10, 12) are the same, and the directions of the currents in the spiral coils (15, 17, 19, 21) are the same, but the direction of the current in the spiral coils (6, 8, 10, 12) is opposite to the direction of the current in the spiral coils (15, 17, 19, 21).

[0107] S52, setting the rotation speed of the conductor disk (14) to 0-3500 [rpm].

[0108] S53, setting the initial values ​​of magnetic potential and electric potential to 0.

[0109] S54. Set the magnetic insulation boundary condition to the outer surface of the spherical calculation domain.

[0110] S6. Set up meshing in COMSOL Multiphysics software.

[0111] S61. Set the mesh size to "fine", select free tetrahedral mesh and perform automatic meshing.

[0112] S62. The total number of grids determined by grid independence analysis is 138546. The grid division and current direction are as follows Figure 3 As shown, Figure 3 A schematic diagram of the grid division and current direction of the eddy current damping element provided in an embodiment of the present application.

[0113] S7. Set the solution type in COMSOL Multiphysics simulation software.

[0114] S71. Set up coil geometry analysis.

[0115] S72. Set up steady-state solution.

[0116] S8. Calculate the research results in COMSOL Multiphysics software.

[0117] S81. Obtain the eddy current axial torque of the conductor disk 14 from the calculation results.

[0118] S82, by formula The eddy current axial torque is converted into the corresponding eddy current damping force.

[0119] Where, fe is the axial eddy current damping force, Te is the eddy current damping torque, is the angular velocity of the conductor disk, η is the transmission efficiency of the ball screw, which is 1.0, and Ld is the lead of the ball screw, which is 30 mm.

[0120] S83. Convert the rotation speed of the conductor disc into the axial speed of the ball screw using the formula:

[0121]

[0122] In the formula, is the axial speed of the ball screw, and Ld is the lead of the ball screw.

[0123] S84, the variation law of eddy current damping force and ball screw axial velocity is plotted as follows Figure 4 As shown, Figure 4 The finite element simulation result diagram of the eddy current damping element provided in the embodiment of the present application is used to obtain the damping characteristics of the half eddy current damping element under different input currents, and identify its peak damping force F max and critical speed v cr .

[0124] S9. Optimize the structural parameters of the eddy current damping element according to the eddy current damping characteristics.

[0125] S91. Change the radius SIR, height SIH and position SIP of the spiral coil (6, 8, 10, 12, 15, 17, 19, 21) respectively to find the optimal parameters that provide the maximum peak damping force and critical speed.

[0126] S92, changing the air gap between the spiral coil (6, 8, 10, 12, 15, 17, 19, 21) and the back iron (3, 25), calculating the relationship between the eddy current damping force and the air gap, and optimizing the size of the air gap MagGap.

[0127] S93, changing the thickness of the back iron (3, 25), calculating the relationship between the eddy current damping force and the back iron thickness BIH, and optimizing the back iron thickness BIH.

[0128] S94, changing the radius TIR of the core (7, 9, 11, 13, 16, 18, 20, 22), calculating the relationship between the eddy current damping force and the core radius, and optimizing the core radius TIR.

[0129] S95. Preferably, the construction parameters are set as follows: CDR=100mm, CDH=3mm, SIR=30mm, SIH=100mm, CoilTurns=800, TIR=5mm, TIH=100mm, BIR=100mm, BIH=5mm, MagGap=2mm, SIP=65mm.

[0130] S10, setting specific parameters of the remaining components of the control device.

[0131] S101. Set the ball screw (2) to have a diameter of 30 mm and a length of 350 mm.

[0132] S102. Set the first thrust bearing (4) and the second thrust bearing (24) to have the same size, with an outer diameter of 60 mm, an inner diameter of 30 mm, a height of 8 mm, a ball diameter of 4 mm, and a distance between the ball center and the thrust bearing center of 55 mm.

[0133] S103, the inner diameter of the nut (5) is set to 30 mm, the outer diameters of the upper and lower ends are set to 60 mm, the height is set to 15 mm, the outer diameter of the middle part is set to 40 mm, and the height is set to 161 mm.

[0134] S104, the outer diameter of the housing (23) is set to 220 mm, the inner diameter is set to 40 mm, the height is set to 217 mm, and the thickness of the upper and lower parts and the side parts is equal, all of which are 5 mm.

[0135] It should be noted that the present application obtains the damping characteristics of the eddy current damping element by simulating the eddy current damping element, that is, the relationship between the eddy current damping force and the rotation speed of the conductor disk, thereby providing parameters to be identified for the subsequent control system, optimizing the structural parameters of the eddy current damping element, and improving energy consumption efficiency.

[0136] See also Figure 5 , is a structural schematic diagram of a control system for a long-span bridge cable provided in an embodiment of the present application, the system comprising a signal acquisition module 100, a calculation and analysis module 200 and a damping force output module 300, the damping force output module comprising the control device according to claims 1-7;

[0137] The signal acquisition module 100 is used to collect the vibration response signal of the cable and send it to the calculation and analysis module;

[0138] The calculation and analysis module 200 is used to calculate the optimal input current of the control device according to the vibration response signal using a preset algorithm;

[0139] The damping force output module 300 is used to transmit the optimal input current to the control device, so that the control device outputs the damping force of the eddy current damping element, and the damping force acts on the inclined cable.

[0140] In a possible implementation, the computing and analyzing module is specifically used to:

[0141] According to the structural parameters of the cable, the optimal damping coefficient of each order vibration mode of the cable is calculated by using the relationship between the additional modal damping ratio and the damping coefficient of the viscous damper;

[0142] Calculating and analyzing the vibration response of the cable obtained by the signal acquisition module to obtain the real-time vibration mode of the cable and the optimal damping coefficient of the cable under the real-time vibration mode;

[0143] Establishing an equivalent damping coefficient expression of the eddy current damping element;

[0144] Calculating the equivalent damping coefficient of the eddy current damping element under different currents;

[0145] According to the optimal damping coefficient and the equivalent damping coefficient, the optimal input current of the eddy current damping element is obtained.

[0146] In a possible implementation, the damping force output module is specifically used to:

[0147] According to the optimal input current and the vibration response signal of the inclined cable, the control device outputs the damping force of the eddy current damping element, which acts on the inclined cable through the first connecting member.

[0148] It can be understood that the embodiments of the present application utilize the displacement response of the vibration of the inclined cable to determine the vibration mode order; calculate the optimal damping coefficient of the vibration of the inclined cable according to the dominant mode frequency of the vibration; establish an equivalent damping coefficient expression for the eddy current damper; calculate the eddy current equivalent damping coefficient under different input currents; determine the optimal input current value; obtain the actual output of the eddy current damper based on the optimal input current of the eddy current damper and apply it to the inclined cable.

[0149] Through the control system provided in the embodiment of the present application, the input current of the eddy current damping element can be adjusted in real time according to the order of the vibration mode of the inclined cable, so that for each order of vibration mode of the inclined cable, the damping coefficient of the eddy current damping element can be close to the optimal damping coefficient of the vibration mode, thereby realizing real-time optimal control.

[0150] Next, the embodiment of the present application is described in detail using a specific scenario example.

[0151] like Figure 6 The figure is a schematic diagram of a working process of a control system provided in an embodiment of the present application.

[0152] S1. A displacement sensor is installed at the damper installation position on the cable to measure the displacement response of the cable vibration.

[0153] S2. According to the structural design parameters of the cable, the optimal damping coefficient of each vibration mode is calculated by using the relationship between the additional modal damping ratio and the damping coefficient of the viscous damper, and the damper installation position is defined as 0.015L away from the anchor end of the cable and the bridge deck in the vertical plane of the cable, where L is the length of the cable. The specific calculation method is an existing technical solution and will not be repeated here.

[0154] S3. Calculate the optimal damping coefficient of the cable under the real-time vibration mode.

[0155] S31. Perform a short-time Fourier transform (STFT) on the displacement response time history measured by the displacement sensor to obtain the relationship between the vibration frequency and amplitude of the inclined cable, that is, the displacement response spectrum. Short-time Fourier transform (STFT) is an existing technology, so it will not be described in detail.

[0156] S32. Define the first three frequencies (f1, f2, f3) with the largest amplitudes as the dominant frequencies of the cable vibration.

[0157] S33. Determine the first three dominant modal orders of vibration by comparing the dominant frequency with the values ​​of the natural frequencies of each order of the cable.

[0158] S34, get the optimal damping coefficient C corresponding to the first three dominant frequencies n,opt , and then determine the final optimal damping coefficient C based on the amplitude ratio of these three-order frequencies opt .

[0159]

[0160] Where S1, S2, and S3 are the amplitudes of the first three dominant frequencies, respectively, and C 1,opt , C 2,opt , C 3,opt They are the optimal damping coefficients corresponding to the first three dominant frequencies (f1, f2, f3).

[0161] S4. Establish the equivalent damping coefficient expression of the nonlinear damping of the semi-active eddy current damper (eddy current damping element).

[0162] S41. Since the relationship between the damping characteristics of the eddy current damper and the speed is significantly nonlinear, the following formula is used to describe it:

[0163]

[0164] Where: F max is the peak damping force, v cr is the critical speed of the eddy current damping force, F under different currents max and v cr All of these can be calculated and analyzed by the semi-active eddy current damping simulation model established in COMSOL simulation software. The results are as follows: Figure 4 As shown, is the axial velocity of the damper.

[0165] S42. According to the equivalent linearization principle, the equivalent damping coefficient c of the corresponding nonlinear damper is obtained by assuming that the energy consumption of the damping force in one cycle is equal to the linear viscous damping force. eq .

[0166]

[0167] Where: is the speed of the cable at the damper installation, T n is the vibration period of the cable.

[0168] S43, Assume that the damper and the cable are in simple harmonic motion, u d (t) = u d sin(ω n t), where: is the cable vibration frequency, and n is the modal order. dSubstituting (t) and equation (2) into equation (3), the equivalent damping coefficient of the eddy current damper can be obtained as:

[0169]

[0170] Where: u p is the displacement response amplitude of the cable vibration at the damper installation location.

[0171] S5. Calculate the equivalent damping coefficient of semi-active eddy current under different currents.

[0172] Assume that the current value is between 0 and I max linearly distributed between them and stored in ascending order in the current vector I F In the example, the vibration displacement amplitude of the cable measured by the sensor and the F corresponding to different current inputs are max and v cr Passed to the equivalent damper coefficient expression, the eddy current equivalent damping coefficient database vector C is calculated i,eq

[0173] I F (i)=I max ×(i-1) / (n I -1)(5)

[0174] Where i = 1, 2, ..., n I , and n I =50,I max is the maximum current, which is taken as 5A.

[0175] S6. Obtain the optimal input current of the damper by comparing the equivalent damping coefficient with the optimal damping coefficient.

[0176] S61, optimal equivalent damping coefficient C n,opt with I F (i) The corresponding available equivalent damping coefficient C i,eq The absolute difference between them is represented as a vector D, namely:

[0177] D(i)=|c n,opt -c i,eq |(6)

[0178] S62. Determine the jth element in vector D so that D(j)=min(D). Therefore, C i,eq (j) represents the equivalent damping coefficient that is most consistent with the required control force. opt =I F (j).

[0179] S7, the optimal input current I optThe electric current is transmitted to the eddy current damping element. The semi-active eddy current damper outputs the damping force according to the optimal input current and the vibration response of the cable. The actual total output of the semi-active eddy current damper acts on the cable to achieve real-time optimal control of the cable vibration.

[0180] It can be seen from the above technical scheme that the ball screw transmission system of the embodiment of the present application includes a signal acquisition module, a calculation and analysis module and a damping force output module. The damping force output module includes a control device. The control system can adjust the input current of the eddy current damping element in real time according to the order of the vibration mode of the inclined cable, so that for each order of vibration mode of the inclined cable, the damping coefficient of the eddy current damping element can be near the optimal damping coefficient of the vibration mode, thereby achieving optimal control.

[0181] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.

[0182] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0183] Those skilled in the art can understand that the flowchart shown in the figure is only an example in which the embodiments of the present application can be implemented, and the scope of application of the embodiments of the present application is not limited by any aspect of the flowchart.

[0184] In the several embodiments provided in the present application, it should be understood that the disclosed methods, devices and equipment can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the device or unit can be electrical, mechanical or other forms.

[0185] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control device for a long-span bridge cable, characterized in that: The device comprises: an eddy current damping element, a ball screw transmission system, a first connecting member and a second connecting member; the eddy current damping element comprises a conductor disk; One end of the first connecting member is connected to the inclined cable, and the other end of the first connecting member is connected to the eddy current damping element; One end of the second connecting member is connected to the eddy current damping element, and the other end of the second connecting member is connected to the bridge deck supporting structure; Two ends of the ball screw transmission system are respectively connected to the first connecting member and the second connecting member; The ball screw transmission system is used to convert the relative axial motion generated at both ends of the eddy current damping element into the high-speed rotational motion of the conductor disk, so that the eddy current damping element generates a damping force; The eddy current damping element is used to generate a damping effect according to the input current, hinder the high-speed rotation of the conductor disk, and dissipate the energy generated by the vibration of the inclined cable.

2. The device according to claim 1, characterized in that The eddy current damping element further comprises: a first back iron, a second back iron and an energized spiral coil fixed between the first back iron and the second back iron; The energized spiral coil comprises an upper energized spiral coil, a lower energized spiral coil and the conductor disk, wherein the conductor disk is arranged between the upper energized spiral coil and the lower energized spiral coil; The first back iron and the second back iron are respectively used to fix the energized spiral coil; The energized spiral coil is used to generate a magnetic field that varies with the magnitude of the current after being energized; The conductor disk is used to cut magnetic lines of force in the magnetic field to generate induced eddy currents. The induced eddy currents interact with the magnetic field generated by the energized spiral coil to generate a Lorentz force that hinders the relative movement between the conductor disk and the energized spiral coil, so as to dissipate the energy generated by the vibration of the inclined cable.

3. The device according to claim 2, characterized in that The spiral coils at corresponding positions of the upper powered spiral coil and the lower powered spiral coil have the same magnetization direction, the current directions between the adjacent upper powered spiral coil and the lower powered spiral coil are opposite, and the magnetic poles are arranged in an alternating positive and negative manner; The upper energized spiral coil comprises: a first upper energized spiral coil, a second upper energized spiral coil, a third upper energized spiral coil and a fourth upper energized spiral coil; The lower powered spiral coil includes: a first lower powered spiral coil, a second lower powered spiral coil, a third lower powered spiral coil and a fourth lower powered spiral coil.

4. The device according to claim 1, characterized in that The ball screw transmission system comprises a ball screw and a nut, wherein the ball screw comprises a ball; and the nut has a guide groove inside that matches the ball; The eddy current damping element is installed in the middle of the ball screw, has the same axis as the ball screw, and is connected to the nut; When the force generated by the axial movement is transmitted to one end of the ball screw and the nut respectively, the balls roll on the guide grooves, and the axial movement is converted into the rotational movement of the nut through the rolling.

5. The device according to claim 2, characterized in that The control device further comprises a housing, the housing comprising an upper circular surface, a lower circular surface and a cylindrical side surface between the upper circular surface and the lower circular surface, the upper circular surface being connected to the first back iron, and the lower circular surface being connected to the second back iron; The housing is used to protect the eddy current damping element.

6. The device according to claim 2, characterized in that The first back-iron and the second back-iron are made of materials with high magnetic permeability.

7. The device according to claim 1, characterized in that The conductor disk is made of non-ferromagnetic material with high electrical conductivity.

8. A control system for a long-span bridge cable, characterized in that: The system comprises a signal acquisition module, a calculation and analysis module and a damping force output module, wherein the damping force output module comprises the control device as claimed in claims 1 to 7; The signal acquisition module is used to collect the vibration response signal of the cable and send it to the calculation and analysis module; The calculation and analysis module is used to calculate the optimal input current of the control device according to the vibration response signal using a preset algorithm; The damping force output module is used to transmit the optimal input current to the control device, so that the control device outputs the damping force of the eddy current damping element, and the damping force acts on the inclined cable.

9. The control system according to claim 8, characterized in that: The computing and analysis module is specifically used for: According to the structural parameters of the cable, the optimal damping coefficient of each order vibration mode of the cable is calculated by using the relationship between the additional modal damping ratio and the damping coefficient of the viscous damper; Calculating and analyzing the vibration response of the cable obtained by the signal acquisition module to obtain the real-time vibration mode of the cable and the optimal damping coefficient of the cable under the real-time vibration mode; Establishing an equivalent damping coefficient expression of the eddy current damping element; Calculating the equivalent damping coefficient of the eddy current damping element under different currents; According to the optimal damping coefficient and the equivalent damping coefficient, the optimal input current of the eddy current damping element is obtained.

10. The system according to claim 9, characterized in that The damping force output module is specifically used for: According to the optimal input current and the vibration response signal of the inclined cable, the control device outputs the damping force of the eddy current damping element, which acts on the inclined cable through the first connecting member.

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