Friction-magnetic array composite energy harvester device based on magnetic bistability

Abstract

The invention discloses a friction-magnetic array composite energy harvester device based on magnetic bistability, which comprises an energy conditioning module, a friction-moving iron electromagnetic power generation module and a static module, and is characterized in that the energy conditioning module comprises a rectification circuit and an electrolytic capacitor, and the static module is connected with a vibration source in a rigid connection mode; external vibration excitation can be directly coupled, and the excitation can be transmitted to the friction-moving iron electromagnetic power generation module. The friction-moving iron electromagnetic power generation module outputs an alternating current signal to the energy conditioning module based on the friction power generation principle and the electromagnetic induction principle, then the alternating current signal is rectified into a direct current signal through a rectifying circuit in the energy conditioning module, the direct current signal is stored in an electrolytic capacitor, and finally the direct current signal is output to the micro-power consumption equipment. And normal operation of equipment is maintained.

Description

Technical Field

[0001] The present invention belongs to the technical field of vibration energy generation, and particularly relates to a friction-magnetic array composite energy harvester device based on magnetic bistability. Background Art

[0002] Vibrations widely exist in various environments. Developing energy harvester devices to collect vibration energy and drive a generator to generate electricity, and then provide a stable power supply for various low-power components is regarded as an effective environmental protection measure. Since the first report of the triboelectric nanogenerator (TENG) in 2012, it has received extensive attention due to its low cost, high conversion efficiency, small size, and sustainability. There are four working modes of triboelectric energy harvesters. One is the vertical contact-separation mode that is convenient for collecting energy such as impacts. The second is the in-plane sliding mode that is convenient for integration and packaging. The third is a more practical and flexible single-electrode mode. The fourth is the independent triboelectric layer mode that can collect the kinetic energy during human movement without contact. Since the in-plane sliding mode is convenient for integration and packaging and can maximize the collection of sliding mechanical energy, a friction disk type energy harvester is designed based on this mode.

[0003] Electromagnetic energy harvesters have the main advantages of high durability, low mechanical wear rate, wide frequency band, high sensitivity, and scalability due to their special working principles and topological structures. Electromagnetic energy harvesters are divided into three types according to the movement mode or structural innovation of the vibrating components. The first is the moving-iron type (coil fixed, magnet vibrating) with an easy-to-design structure. The second is the moving-coil type (permanent magnet fixed, coil vibrating) suitable for miniaturization design. The third is the iron-coil co-vibrating type (magnet and coil co-vibrating) that can enhance the magnetic flux change through two-degree-of-freedom movement. In order to maximize the energy density, an electromagnetic energy harvester is designed in the remaining space of the friction disk.

[0004] Currently, traditional energy harvesters mainly focus on unidirectional energy collection. However, there are many energy-rich sources in various directions in environments such as train bogies, ocean waves, and human walking. Collecting this energy and supplying power to sensors can further improve the energy utilization rate. On the other hand, since traditional vibration energy harvesters have a natural frequency, when the working frequency of the external excitation is close to it, the structural response of the traditional vibration energy harvester is the largest, and the corresponding energy conversion rate is also the largest. At this time, the system will have a greater power output. However, this method will cause the working frequency band of the system to be too narrow, which is not conducive to the use of the energy harvester in a wider frequency band. To solve this problem, a magnetic dipole (providing a non-linear force for the system) model is hereby introduced. Summary of the Invention

[0005] The object of the present invention is to solve the above problems and provide a friction-magnetic array composite energy harvester device based on magnetic bistability with a simple structure and a high energy conversion rate.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows: A friction-magnetic array composite energy harvesting device based on magnetic bistability, characterized in that it includes an energy conditioning module, a friction-moving iron electromagnetic power generation module, and a static module. The energy conditioning module includes a rectifying circuit and an electrolytic capacitor. The static module is connected to the vibration source in a rigid connection manner, which can directly couple external vibration excitation and transfer the excitation to the friction-moving iron electromagnetic power generation module. The friction-moving iron electromagnetic power generation module outputs an alternating current signal to the energy conditioning module based on the friction power generation principle and the electromagnetic induction principle respectively. Then, the alternating current signal is rectified into a direct current signal by the rectifying circuit in the energy conditioning module and stored in the electrolytic capacitor. Finally, the direct current signal is output to a micro-power consumption device to maintain the normal operation of the device.

[0007] Preferably, the static module includes an upper horizontal fixing rod, a right upper coil support, a right upper copper coil winding, a right support plate, a fixing shaft, a square fixing support, a rear cover plate, a right lower coil support, a right lower copper coil winding, a front cover plate, a lower bottom plate, an upper cover plate, a left upper coil support, a left upper copper coil winding, a left support plate, a copper film, a polytetrafluoroethylene film, a lower horizontal fixing rod, a fixed magnet, a movable magnet support, a left lower coil support, and a left lower copper coil winding. The upper cover plate, the right support plate, the lower bottom plate, and the left support plate are connected by L-shaped 3D parts to form a rectangular frame structure. Each L-shaped 3D part is connected to the frame using bolt fasteners. The fixing shaft passes through the geometric centers of the front cover plate and the rear cover plate in sequence and is then connected to the square fixing support. The movable magnet support is pasted on the lower bottom plate using strong glue. The left lower coil support is fixedly connected to the static module, and the left lower copper coil winding is concentratedly wound on the left lower coil support. The right lower coil support is fixedly connected to the static module, and the right lower copper coil winding is concentratedly wound on the right lower coil support. Then, the lower horizontal fixing rod passes through the left lower coil support and the right lower coil support in sequence to form a lower fixing component. The lower horizontal fixing rod of this component is embedded in the counterbores of the left lower coil support and the right lower coil support, and the lower horizontal fixing rod is kept in a pre-tightened state through interference fit. The left upper copper coil winding is wound on the left upper coil support, and the right upper copper coil winding is wound on the right upper coil support. The upper horizontal fixing rod passes through the left upper coil support and the right upper coil support in sequence to form an upper fixing component. The upper horizontal fixing rod of this component is embedded in the counterbores of the left upper coil support and the right upper coil support, and the upper horizontal fixing rod is kept in a pre-tightened state through interference fit.

[0008] Preferably, the front cover plate and the rear cover plate are bonded to the two square fixing supports using strong glue. A stretching structure is designed on both the inner side of the front cover plate and the outer side of the rear cover plate and independently forms 5 sector block structures. On each sector block, a layer of copper film is first covered, and then a layer of polytetrafluoroethylene (PTFE) film is evenly pasted to form one pole of the friction power generation module with the copper film.

[0009] Preferably, a fixed nut is provided inside the movable magnet support. The fixed magnet is located inside the movable magnet support. A movable bolt passes through the bottom of the movable magnet support, and the end of the movable bolt is screwed into the fixed nut. The end of the movable bolt is adhered to the fixed magnet. The movable magnet support, the fixed magnet, the fixed nut, and the movable bolt constitute an adjustable magnetic gap assembly. The function of the adjustable magnetic gap assembly is to adapt the magnetic gap derived based on the magnetic dipole theory to the gap between the mutually repulsive magnets in the experiment, ensuring the normal operation of the energy harvesting system within the preset bandwidth.

[0010] Preferably, the friction - moving - iron electromagnetic power generation module includes a rotating friction gear, a left - lower horizontal tension - compression spring, a left - lower hollow cylindrical permanent magnet, a lower - horizontal movable rack, a right - lower hollow cylindrical permanent magnet, a right - lower horizontal tension - compression spring, a left - upper hollow cylindrical permanent magnet, an upper - horizontal movable rack, and a right - upper hollow cylindrical permanent magnet. The left - lower hollow cylindrical permanent magnet and the right - lower hollow cylindrical permanent magnet are nested on the lower - horizontal movable rack. Then, the left - lower horizontal tension - compression spring and the right - lower horizontal tension - compression spring are synchronously sleeved on the lower - horizontal fixed rod of the static module and jointly form a lower moving - iron electromagnetic power generation module with the lower fixed component in the static module. The left - upper hollow cylindrical permanent magnet and the right - upper hollow cylindrical permanent magnet are nested on the upper - horizontal movable rack and jointly form an upper moving - iron electromagnetic power generation module with the upper fixed component in the static module. When the static module transfers a lateral external excitation to the lower - horizontal movable rack through a rigid connection, due to the lower - horizontal movable rack being simultaneously affected by the inertial force and the elastic forces of the left - lower horizontal tension - compression spring and the right - lower horizontal tension - compression spring, the rack will deviate from the equilibrium position and perform reciprocating motion along the lower - horizontal fixed rod, thereby forcing the rotating friction gear to rotate. The front cover plate and the rear cover plate in contact with the rotating friction gear rub against each other. Since the polarities of the copper film on the rotating friction gear and the polymer plastic films of the front cover plate and the rear cover plate are different, an alternating current signal is generated during their frictional motion. At the same time, during the reciprocating motion of the lower - horizontal movable rack, relative motion will be caused between the left - lower hollow cylindrical permanent magnet and the right - lower hollow cylindrical permanent magnet and the left - lower copper coil winding and the right - lower copper coil winding, further cutting the magnetic induction lines to output an alternating current signal. The rotation of the rotating friction gear will drive the upper - horizontal movable rack to perform reciprocating motion, and during the motion of the upper - horizontal movable rack, relative motion will be caused between the left - upper hollow cylindrical permanent magnet and the right - upper hollow cylindrical permanent magnet and the left - upper copper coil winding and the right - upper copper coil winding, thereby cutting the magnetic induction lines to output an alternating current signal.

[0011] Preferably, a moving magnet is embedded in the lower - horizontal movable rack, which forms a mutually repulsive magnetic dipole with the fixed magnet in the movable magnet support of the static module, providing a non - linear restoring force for the energy capture device, broadening the working bandwidth of the system, and enhancing the output power.

[0012] Preferably, tensile bosses are designed on both the inner and outer sides of the rotating friction gears that mesh with the lower horizontal moving rack, and copper films are evenly pasted on the tensile bosses.

[0013] Preferably, the upper moving-iron electromagnetic power generation module is used as a driven part and no tension-compression spring is designed.

[0014] Preferably, the energy conditioning module includes a friction generator input interface, a moving-iron electromagnetic generator input interface, a rectifying circuit, direct current, and electrolytic capacitors. The friction-moving-iron electromagnetic power generation module is respectively connected to the friction generator input interface and the moving-iron electromagnetic generator input interface. The two interfaces input the received electrical signals into the rectifying circuit, which converts the alternating current signal into a direct current signal and then inputs it into the electrolytic capacitors for storage, and finally provides stable energy for low-power-consuming devices such as sensors.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. The friction-magnetic array composite energy harvester device based on magnetic bistability provided by the present invention uses two sets of gear-rack structures to collect lateral vibration energy, combines the principles of friction power generation and electromagnetic induction, and applies them to the designed device together to finally realize vibration energy collection.

[0017] 2. A gear disk pasted with a copper dielectric film is designed in the present invention, which can enable the energy harvester to have a high energy density in a small volume, and the reasonable physical structure design is beneficial to its operation in a small-scale space.

[0018] 3. Two sets of magnetic arrays are designed in the present invention. The reciprocating movement of the rack is used to drive the movement of the hollow cylindrical magnet, which forms a relative movement with the fixed concentrated coil winding during the movement process, and further outputs an electrical signal by cutting the magnetic induction line, thereby improving the output power of the energy harvester.

[0019] 4. Four pairs of mutually exclusive magnetic dipoles are designed in the present invention. The non-linear restoring force provided by the magnet enables the moving rack to break through the potential energy barrier and perform inter-well movement in some frequency bands, increasing the structural response of the system and broadening the working frequency band of the energy harvester. Description of the Drawings

[0020] Figure 1 is a structural schematic diagram of a friction-magnetic array composite energy harvester device based on magnetic bistability of the present invention;

[0021] Figure 2 is an assembly drawing of the static module of the present invention;

[0022] Figure 3 is a friction-moving-iron electromagnetic power generation module diagram of the present invention;

[0023] Figure 4 It is the diagram of the energy conditioning module of the present invention;

[0024] Figure 5 It is the structural diagram of the adjustable magnetic gap component of the present invention;

[0025] Figure 6 It is the structural diagram of the coil support of the present invention;

[0026] Figure 7 It is the schematic diagram of the electromagnetic power generation module of the composite energy harvesting device of the present invention.

[0027] Explanation of reference numerals: 1. Energy conditioning module; 2. Friction-moving iron electromagnetic power generation module; 3. Static module; 10. Upper horizontal fixing rod; 11. Right upper coil support; 12. Right upper copper coil winding; 13. Right support plate; 14. Fixed shaft; 15. Square fixed support; 16. Rear cover plate; 17. Right lower coil support; 18. Right lower copper coil winding; 19. Front cover plate; 20. Lower bottom plate; 21. Upper cover plate; 22. Left upper coil support; 23. Left upper copper coil winding; 24. Left support plate; 25. Copper film; 26. Polytetrafluoroethylene film; 27. Lower horizontal fixing rod; 28. Fixed magnet; 29. Movable magnet support; 30. Left lower coil support; 31. Left lower copper coil winding; 40. Right upper hollow cylindrical permanent magnet; 41. Upper horizontal movable rack; 42. Rotating friction gear; 43. Outer copper film of friction disc; 44. Inner copper film of friction disc; 45. Right lower horizontal tension-compression spring; 46. Right lower hollow cylindrical permanent magnet; 47. Lower horizontal movable rack; 48. Left upper hollow cylindrical permanent magnet; 49. Left lower horizontal tension-compression spring; 50. Left lower hollow cylindrical permanent magnet; 51. Moving magnet; 60. Rectifier circuit; 61. Direct current; 62. Electrolytic capacitor; 63. Input interface of friction generator; 64. Input interface of moving iron electromagnetic generator; 72. Fixed nut; 73. Movable bolt. Detailed implementation manners

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0029] As Figures 1 to 7As shown in the figure, a friction-magnetic array composite energy harvesting device based on magnetic bistability provided by the present invention includes an energy conditioning module 1, a friction-moving iron electromagnetic power generation module 2, and a static module 3. The energy conditioning module 1 includes a rectifying circuit 60 and an electrolytic capacitor 62. The static module 3 is connected to the vibration source in a rigid connection manner, which can directly couple external vibration excitation and transmit the excitation to the friction-moving iron electromagnetic power generation module 2. The friction-moving iron electromagnetic power generation module 2 outputs an alternating current signal to the energy conditioning module 1 based on the principles of triboelectric power generation and electromagnetic induction respectively. Then, the rectifying circuit 60 in the energy conditioning module 1 rectifies the alternating current signal into a direct current signal and stores it in the electrolytic capacitor 62. Finally, the direct current signal is output to the micro-power consumption device to maintain the normal operation of the device. In this embodiment, the micro-power consumption device is an existing device, such as a light-emitting diode. The vibration source is an existing device that can generate vibration.

[0030] As Figure 2 As shown in the figure, the static module 3 includes an upper horizontal fixing rod 10, a right upper coil support 11, a right upper copper coil winding 12, a right support plate 13, a fixing shaft 14, a square fixing support 15, a rear cover plate 16, a right lower coil support 17, a right lower copper coil winding 18, a front cover plate 19, a lower bottom plate 20, an upper cover plate 21, a left upper coil support 22, a left upper copper coil winding 23, a left support plate 24, a copper film 25, a polytetrafluoroethylene film 26, a lower horizontal fixing rod 27, a fixed magnet 28, a movable magnet support 29, a left lower coil support 31, and a left lower copper coil winding 30. The upper cover plate 21, the right support plate 13, the lower bottom plate 20, and the left support plate 24 are connected by L-shaped 3D parts to form a rectangular frame structure. Each L-shaped 3D part is connected to the frame using bolt fasteners. The fixing shaft 14 passes through the geometric centers of the front cover plate 19 and the rear cover plate 16 in sequence and then is connected to the square fixing support 15.

[0031] The movable magnet support 29 is pasted on the lower bottom plate 20 with strong glue. The bottom of the left lower coil support 31 is provided with a left connecting part, and the left connecting part is a plate-like structure with holes. The left lower coil support 31 is bolted to the static module 3 through the left connecting part. The left lower copper coil winding 30 is wound around the left lower coil support 31 in a concentrated manner. The bottom of the right lower coil support 17 is provided with a right connecting part, and the right connecting part has the same structure as the left connecting part. The right lower coil support 17 is bolted to the static module 3 through the right connecting part. The right lower copper coil winding 18 is wound around the right lower coil support 17 in a concentrated manner. Then, the lower horizontal fixing rod 27 passes through the left lower coil support 31 and the right lower coil support 17 in sequence to form a lower fixing component. The lower horizontal fixing rod 27 of this component is embedded in the counterbores of the left lower coil support 31 and the right lower coil support 17, and the lower horizontal fixing rod 27 is kept in a pre-tightened state through interference fit.

[0032] In this embodiment, the lower left coil support 31 is bolted to the lower base plate 20 through a left connecting member, and the lower right coil support 17 is bolted to the lower base plate 20 through a right connecting member.

[0033] The upper left copper coil winding 23 is wound around the upper left coil support 22, and the upper right copper coil winding 12 is wound around the upper right coil support 11. The upper transverse fixing rod 10 passes through the upper left coil support 22 and the upper right coil support 11 in sequence to form an upper fixing assembly. The upper transverse fixing rod 10 of this assembly is embedded in the counterbores of the upper left coil support 22 and the upper right coil support 11, and the upper transverse fixing rod 10 is kept in a pre-tightened state through interference fit.

[0034] In this embodiment, the lower left coil support 31 includes a lower left coil baffle and a lower left coil cylinder that are fixedly connected together. The lower left coil baffle is a plate-like structure with a lower left coil baffle through-hole in the middle. The lower left coil cylinder is a hollow cylindrical structure with a cross-section in the shape of a "U". The bottom of the lower left coil cylinder is provided with a lower left coil cylinder bottom through-hole, and the end of the lower transverse fixing rod 27 passes through the lower left coil baffle and is located inside the lower left coil cylinder. The lower left coil support 31, the lower right coil support 17, the upper left coil support 22, and the upper right coil support 11 have the same structure.

[0035] The front cover plate 19 and the rear cover plate 16 are bonded to the two square fixing supports 15 using strong glue. A stretching structure is designed on both the inner side of the front cover plate 19 and the outer side of the rear cover plate 16 and independently forms 5 fan-shaped block structures. A copper film is first covered on each fan-shaped block, and then a layer of polytetrafluoroethylene film 26 is evenly pasted to form one pole of the triboelectric power generation module with the copper film.

[0036] The movable magnet support 29 is provided with a fixed nut 72. The fixed magnet 28 is located inside the movable magnet support 29. The bottom of the movable magnet support 29 is provided with a movable bolt 73. The end of the movable bolt 73 is screwed into the fixed nut 72, and the end of the movable bolt 73 is bonded to the fixed magnet 28. The movable magnet support 29, the fixed magnet 28, the fixed nut 72, and the movable bolt 73 constitute an adjustable magnetic gap assembly. The function of the adjustable magnetic gap assembly is to adapt the magnetic gap derived based on the magnetic dipole theory to the repulsive magnet gap in the experiment, ensuring the normal operation of the energy harvesting system within the preset bandwidth.

[0037] In this embodiment, the movable magnet support 29 includes a movable magnet support block and movable magnet support feet that are integrally connected. The number of movable magnet support feet is 4, and the cross-section of the movable magnet support feet is trapezoidal, and the four relatively arranged sides of the trapezoid are arc-shaped. The specific value of the magnetic gap and the repulsive magnet gap is 5.6 mm.

[0038] As Figure 3As shown in the figure, the friction-moving iron electromagnetic power generation module 2 includes a rotating friction gear 42, a left-lower horizontal tension-compression spring 49, a left-lower hollow cylindrical permanent magnet 50, a lower horizontal moving rack 47, a right-lower hollow cylindrical permanent magnet 46, a right-lower horizontal tension-compression spring 45, a left-upper hollow cylindrical permanent magnet 48, an upper horizontal moving rack 41, and a right-upper hollow cylindrical permanent magnet 40. The left-lower hollow cylindrical permanent magnet 50 and the right-lower hollow cylindrical permanent magnet 46 are nested on the lower horizontal moving rack 47, and then the left-lower horizontal tension-compression spring 49 and the right-lower horizontal tension-compression spring 45 are synchronously sleeved on the lower horizontal fixed rod 27 of the static module 3, and together with the lower fixed component in the static module 3, they form a lower moving iron electromagnetic power generation module. The left-upper hollow cylindrical permanent magnet 48 and the right-upper hollow cylindrical permanent magnet 40 are nested on the upper horizontal moving rack 41, and together with the upper fixed component in the static module 3, they form an upper moving iron electromagnetic power generation module. When the static module 3 transfers the lateral external excitation to the lower horizontal moving rack 47 through a rigid connection, due to the combined action of the inertial force and the elastic forces of the left-lower horizontal tension-compression spring 49 and the right-lower horizontal tension-compression spring 45 on the lower horizontal moving rack 47, the rack will deviate from the equilibrium position and perform reciprocating motion along the lower horizontal fixed rod 27, thereby forcing the rotating friction gear 42 to perform a rotating motion. The front cover plate 19 and the rear cover plate 16 that are in contact with the rotating friction gear 42 rub against each other. Since the polarities of the copper film on the rotating friction gear 42 and the polymer plastic films of the front cover plate 19 and the rear cover plate 16 are different, the friction motion between the two will generate an alternating current signal. At the same time, during the reciprocating motion of the lower horizontal moving rack 47, it will cause relative motion between the left-lower hollow cylindrical permanent magnet 50 and the right-lower hollow cylindrical permanent magnet 46 and the left-lower copper coil winding 30 and the right-lower copper coil winding 18, further cutting the magnetic induction lines to output an alternating current signal. The rotation of the rotating friction gear 42 will drive the upper horizontal moving rack 41 to perform reciprocating motion. During the motion of the upper horizontal moving rack 41, it will cause relative motion between the left-upper hollow cylindrical permanent magnet 48 and the right-upper hollow cylindrical permanent magnet 40 and the left-upper copper coil winding 23 and the right-upper copper coil winding 12, thereby cutting the magnetic induction lines to output an alternating current signal.

[0039] A moving magnet 51 is embedded on the lower horizontal moving rack 47, which forms a mutually repulsive magnetic dipole with the fixed magnet 28 in the moving magnet support 29 of the static module 3, providing a non-linear restoring force for the energy harvesting device, broadening the working bandwidth of the system, and improving the output power.

[0040] Tensile bosses are designed on both the inner and outer sides of the rotating friction gear 42 that meshes with the lower horizontal moving rack 47, and copper films are evenly pasted on the tensile bosses. In this embodiment, the copper films evenly pasted on the tensile bosses are the outer friction disk copper film 43 and the inner friction disk copper film 44 respectively.

[0041] As a driven part, the upper moving iron electromagnetic power generation module is not designed with a tension-compression spring.

[0042] As Figure 4 shown, the energy conditioning module 1 includes a tribogenerator input interface 63, a moving-iron electromagnetic generator input interface 64, a rectifier circuit 60, direct current 61, and an electrolytic capacitor 62. The tribo-moving-iron electromagnetic power generation module 2 is respectively connected to the tribogenerator input interface 63 and the moving-iron electromagnetic generator input interface 64. The two interfaces input the received electrical signals into the rectifier circuit 60, which converts the alternating current signal into a direct current signal and then inputs it into the electrolytic capacitor 62 for storage, and finally provides a stable energy source for low-power devices such as sensors.

[0043] The static module 3 of the present invention directly couples the external excitation to the friction medium of the tribogeneration module in the tribo-moving-iron electromagnetic power generation module 2 and the sliding magnet of the moving-iron electromagnetic power generation module respectively, then rectifies the alternating current signal through the energy conditioning module 1, and supplies energy to the load, ultimately realizing the recovery and utilization of vibration energy. In this embodiment, the friction medium refers to a copper film and a polytetrafluoroethylene film 26.

[0044] As Figure 5 shown, the working principle of the moving-iron electromagnetic generator of the tribo-magnetic array composite energy harvester based on magnetic bistability is described. The working process and principle of the present invention are as follows:

[0045] The working principle of the friction-magnetic array composite energy harvester based on magnetic bistability is further explained below. The static module 3 is fixedly connected to the vibration source through a rigid structure and transmits the lateral excitation to the left-lower lateral tension-compression spring 49 and the right-lower lateral tension-compression spring 45. The two springs apply elastic forces to the lower lateral movable rack 47, and the movable rack makes reciprocating motions under the combined action of inertial force and elastic force. At the same time, the rotating friction gear 42 meshing with the movable rack rotates synchronously. The copper dielectric films symmetrically arranged before and after on the rotating friction gear 42 come into contact and friction with the polytetrafluoroethylene films of the rear cover plate 16 and the front cover plate 19 of the static module 3 respectively during the movement process to output an alternating current signal. On the other hand, since the left-lower hollow cylindrical permanent magnet 50 and the right-lower hollow cylindrical permanent magnet 46 are compounded at both ends of the lower lateral movable rack 47, when there is relative movement between the rack and the static module 3, there is relative movement between the hollow cylindrical permanent magnets and the left-lower copper coil winding 30 and the right-lower copper coil winding 18 in the static module 3, resulting in a change in magnetic flux. In addition, the upper lateral movable rack 41 meshing with the rotating friction gear 42 makes reciprocating motions synchronously. The left-upper hollow cylindrical permanent magnet 48 and the right-upper hollow cylindrical permanent magnet 40 compounded on the upper lateral movable rack 41 have relative movements with the left-upper copper coil winding 23 and the right-upper copper coil winding 12 in the static module 3 respectively, resulting in a change in magnetic flux. The two moving-iron electromagnetic power generation modules will output an alternating current signal. The electrical signals output by the friction-magnetic array composite energy harvester are transmitted to the friction generator input interface 63 and the moving-iron electromagnetic generator input interface 64 of the energy conditioning module 1 through their respective output interfaces. The alternating current signal is converted into a direct current signal through the rectifying circuit 60 and stored in the electrolytic capacitor 62, and finally provides a stable power supply for energy-consuming components such as sensors.

[0046] The mechanism analysis of the friction power generation module based on the triboelectric effect is very important. The designed energy harvester is composed of multiple components. In order to accurately calculate the dynamic response of the structural components of the energy harvesting system, the magnetic potential energy U of the magnetic dipole is calculated first. mag . The nonlinear restoring force between the designed laterally repulsive neodymium disc magnets is expressed as:

[0047]

[0048] Finally, numerical analysis of m, k, and c is obtained based on the Lagrange equation:

[0049]

[0050] In the formula, the mass of the rack m rack = 49 g, the mass of the friction disc m disk = 132 g, the spring stiffness k = 33.67 k / m, the magnetic permeability μ0 in vacuum = 4π×10 -7 Wb(Am) -1, the magnetic dipole moment M = 0.16 Wb m, the magnet gap g mag = 5.6 mm, and d represents the center distance between the two magnets.

[0051] The derivation process of the magnetic force model of the moving iron electromagnetic power generation module is as follows. There are three theoretical derivation methods for the magnetic induction intensity of a hollow cylindrical magnet. The first is the equivalent current model applicable to near-field and internal magnetic field analysis, the second is the equivalent magnetic charge model that is convenient for calculating uniformly magnetized permanent magnets, and the third is the magnetic dipole model only applicable to the far field (r >> magnet size) region of the magnet. The present invention uses the equivalent current model to calculate the magnetic induction intensity of the magnet.

[0052] As a fundamental theory in the field of electromagnetism, the law of electromagnetic induction essentially clarifies the quantitative relationship between a time-varying magnetic field and an induced electric field. Its core content can be expressed as: when the relative motion between a conductor loop and a magnet causes a change in the magnetic flux passing through the closed loop, an induced electromotive force proportional to the rate of change of the magnetic flux will be generated in the loop, that is:

[0053]

[0054] In the formula, E is the induced electromotive force generated in the closed loop, N represents the number of turns of the copper coil, Ψ represents the total magnetic flux passing through the loop, ψ = BA, B represents the magnetic induction intensity vector, and A is the geometric area enclosed by the loop. The direction of the secondary magnetic field excited by the induced current strictly follows Lenz's Law, and its essential role is to hinder the time-domain change of the original magnetic flux Ψ through magnetic interaction. This physical constraint is characterized by the negative sign in the differential relationship. The induced electromotive force E is further described as:

[0055]

[0056] As can be seen from Equation 4, the displacement of the magnetic flux density in the z-axis direction in the coil will affect θ in the electromagnetism e .

[0057] Next, the magnetic induction intensity of the hollow cylindrical magnet is further derived. The selected hollow cylindrical permanent magnet is uniformly magnetized, and its magnetization direction is along the central axis direction. A space cylindrical coordinate system (r, θ, z) is established with the geometric center of the hollow cylindrical permanent magnet as the origin. The outer diameter of the magnet is r out , the inner diameter is r inner , the height is L m , the magnetic induction intensity generated by the permanent magnet is B, which can generate relative motion based on the external displacement excitation y(t). The copper coil is fixed to the housing through a fixed support, and its outer diameter is R out , the median diameter is R middle , the inner diameter is R inner , the height is H c, the gap between the magnet and the coil is d.

[0058] Based on the axisymmetric characteristics of the magnetic field distribution, in the cylindrical coordinate system (r, z), the toroidal magnetic field component remains uniformly distributed at any azimuthal angle position, that is, the toroidal component B of the magnetic induction intensity φ is always zero. Take an infinitesimal current element Idl in the cross-section (z = 0) of the hollow cylindrical permanent magnet perpendicular to the axis and passing through the origin. The differential magnetic induction intensity dB generated by it at any observation point Q(r, z) in the outer space of the permanent magnet can be derived through the Biot-Savart Law:

[0059]

[0060] In the formula, r′ is the vector from the infinitesimal current element Idl to the observation point Q(r, z), μ0 is the vacuum permeability, and I is the surface equivalent current of the permanent magnet.

[0061] Based on Ampere's molecular circulation theory, when the cylindrical permanent magnet satisfies the condition of axial uniform magnetization (that is, the magnetization intensity vector satisfies M = Me z , where M is the material saturation magnetization), its surface equivalent current distribution can be analytically characterized. According to the boundary conditions, for the cylindrical side surface (radius r out , height L m ), the curl of the magnetization intensity and the equivalent surface current density satisfy:

[0062]

[0063] In the formula, J s is the magnetization current density, that is, the equivalent current distribution generated inside the material due to magnetization, is the curl operator, which is an important differential property of the vector field and describes the rotation characteristics of the field at a certain point. δ(·) is the Dirac function, indicating that the current is only distributed on the cylindrical side surface, and e φ is the angular unit vector, indicating that the current direction is along the tangential direction of the cylindrical side surface. Integrating this distribution along the axial direction, since the magnetic field of the hollow cylindrical permanent magnet is assumed to be uniform, the total equivalent circular current intensity is approximately:

[0064]

[0065] This model implicitly assumes that the end face magnetic charge effect can be ignored (that is, the aspect ratio of the cylindrical magnet satisfies L m >> r out , and the contribution of the end face magnetic charge can be ignored), and it is applicable to the static magnetic field approximation condition. Substituting Equation 19 into Equation 17, we get:

[0066]

[0067] AsFigure 7 As shown, for any point Q(r, 0, z) on the xoz plane, let Vr = r out -r inner , the vector r' from the infinitesimal current element Idl to the observation point Q(r, z) is:

[0068] r' = ri + zj - Vr(cosθi + sinθj) (9)

[0069] Finally, through coordinate transformation and elliptic integral, the magnetic field strength is obtained as:

[0070]

[0071] The electrical model of the designed friction-magnetic array composite energy harvester based on magnetic bistability can be approximately modeled by the series connection of a variable capacitor C e and a voltage source V oc . The voltage V oc across the resistor R in the external circuit and the transferred charge quantity Q between the two electrodes can be deduced by combining Ohm's law. Substituting and into the formula, the electrical differential equation of the energy harvester is:

[0072]

[0073] Those of ordinary skill in the art will realize that the embodiments described herein are for helping readers understand the principles of the present invention. It should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention according to these technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A friction-magnetic array composite energy harvester device based on magnetic bistability, characterized in that: It includes an energy conditioning module (1), a tribo - moving iron electromagnetic power generation module (2) and a static module (3). The energy conditioning module (1) includes a rectifier circuit (60) and an electrolytic capacitor (62). The static module (3) is connected to the vibration source in a rigid connection manner. It can directly couple external vibration excitation and transmit the excitation to the tribo - moving iron electromagnetic power generation module (2). The tribo - moving iron electromagnetic power generation module (2) outputs an alternating current signal to the energy conditioning module (1) respectively based on the triboelectric power generation principle and the electromagnetic induction principle. Then, the rectifier circuit (60) in the energy conditioning module (1) rectifies the alternating current signal into a direct current signal and stores it in the electrolytic capacitor (62). Finally, the direct current signal is output to a micro - power consumption device to maintain the normal operation of the device.

2. The friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: The static module (3) includes an upper horizontal fixing rod (10), a right upper coil support (11), a right upper copper coil winding (12), a right support plate (13), a fixing shaft (14), a square fixing support (15), a rear cover plate (16), a right lower coil support (17), a right lower copper coil winding (18), a front cover plate (19), a lower bottom plate (20), an upper cover plate (21), a left upper coil support (22), a left upper copper coil winding (23), a left support plate (24), a copper thin film (25), a polytetrafluoroethylene thin film (26), a lower horizontal fixing rod (27), a fixing magnet (28), a movable magnet support (29), a left lower coil support (31), and a left lower copper coil winding (30). The upper cover plate (21), the right support plate (13), the lower bottom plate (20), and the left support plate (24) are connected by L-shaped 3D parts to form a rectangular frame structure. Each L-shaped 3D part is connected to the frame using bolt fasteners. The fixing shaft (14) passes through the geometric centers of the front cover plate (19) and the rear cover plate (16) in sequence and then is connected to the square fixing support (15). The movable magnet support (29) is adhered to the lower bottom plate (20) using strong glue. The left lower coil support (31) is fixedly connected to the static module (3), and the left lower copper coil winding (30) is wound around the left lower coil support (31) concentrically. The right lower coil support (17) is fixedly connected to the static module (3), and the right lower copper coil winding (18) is wound around the right lower coil support (17) concentrically. Then, the lower horizontal fixing rod (27) passes through the left lower coil support (31) and the right lower coil support (17) in sequence to form a lower fixing assembly. The lower horizontal fixing rod (27) of this assembly is embedded in the counterbores of the left lower coil support (31) and the right lower coil support (17), and the lower horizontal fixing rod (27) is maintained in a pre-tightened state through interference fit. The left upper copper coil winding (23) is wound around the left upper coil support (22), and the right upper copper coil winding (12) is wound around the right upper coil support (11). The upper horizontal fixing rod (10) passes through the left upper coil support (22) and the right upper coil support (11) in sequence to form an upper fixing assembly. The upper horizontal fixing rod (10) of this assembly is embedded in the counterbores of the left upper coil support (22) and the right upper coil support (11), and the upper horizontal fixing rod (10) is maintained in a pre-tightened state through interference fit.

3. A friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: The front cover plate (19) and the rear cover plate (16) are adhered to the two square fixing supports (15) using strong glue. A stretching structure is designed on both the inner side of the front cover plate (19) and the outer side of the rear cover plate (16) and independently forms 5 sector block structures. A layer of copper thin film is first covered on each sector block, and then a layer of polytetrafluoroethylene thin film (26) is evenly pasted to form one pole of the triboelectric power generation module with the copper thin film.

4. A friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: A fixed nut (72) is provided inside the movable magnet support (29). The fixed magnet (28) is located inside the movable magnet support (29). A movable bolt (73) passes through the bottom of the movable magnet support (29). The end of the movable bolt (73) is screwed into the fixed nut (72). The end of the movable bolt (73) is adhered to the fixed magnet (28). The movable magnet support (29), the fixed magnet (28), the fixed nut, and the movable bolt (73) form an adjustable magnetic gap assembly. The function of the adjustable magnetic gap assembly is to adapt the magnetic gap derived based on the magnetic dipole theory to the repulsive magnet gap in the experiment, ensuring the normal operation of the energy harvesting system within the preset bandwidth.

5. The friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: The friction-moving iron electromagnetic power generation module (2) includes a rotating friction gear (42), a left-lower horizontal tension-compression spring (49), a left-lower hollow cylindrical permanent magnet (50), a lower horizontal moving rack (47), a right-lower hollow cylindrical permanent magnet (46), a right-lower horizontal tension-compression spring (45), a left-upper hollow cylindrical permanent magnet (48), an upper horizontal moving rack (41), and a right-upper hollow cylindrical permanent magnet (40); the left-lower hollow cylindrical permanent magnet (50) and the right-lower hollow cylindrical permanent magnet (46) are nested on the lower horizontal moving rack (47), and then the left-lower horizontal tension-compression spring (49) and the right-lower horizontal tension-compression spring (45) are synchronously sleeved on the lower horizontal fixed rod (27) of the static module (3), and then jointly form a lower moving iron electromagnetic power generation module with the lower fixed component in the static module (3); the left-upper hollow cylindrical permanent magnet (48) and the right-upper hollow cylindrical permanent magnet (40) are nested on the upper horizontal moving rack (41), and jointly form an upper moving iron electromagnetic power generation module with the upper fixed component in the static module (3); when the static module (3) transmits a lateral external excitation to the lower horizontal moving rack (47) through a rigid connection, due to the lower horizontal moving rack (47) being simultaneously affected by the inertial force and the elastic forces of the left-lower horizontal tension-compression spring (49) and the right-lower horizontal tension-compression spring (45), the rack will deviate from the equilibrium position and perform a reciprocating motion along the lower horizontal fixed rod (27), thereby forcing the rotating friction gear (42) to perform a rotational motion, and the front cover plate (19) and the rear cover plate (16) in contact with the rotating friction gear (42) will rub against each other. Since the polarities of the copper thin film on the rotating friction gear (42) and the polymer plastic thin films of the front cover plate (19) and the rear cover plate (16) are different, an alternating current signal will be generated by their frictional motion. At the same time, during the reciprocating motion of the lower horizontal moving rack (47), relative motion will be caused between the left-lower hollow cylindrical permanent magnet (50) and the right-lower hollow cylindrical permanent magnet (46) and the left-lower copper coil winding (30) and the right-lower copper coil winding (18), further cutting the magnetic induction lines to output an alternating current signal, and the rotation of the rotating friction gear (42) will drive the upper horizontal moving rack (41) to perform a reciprocating motion. During the motion of the upper horizontal moving rack (41), relative motion will be caused between the left-upper hollow cylindrical permanent magnet (48) and the right-upper hollow cylindrical permanent magnet (40) and the left-upper copper coil winding (23) and the right-upper copper coil winding (12), thereby cutting the magnetic induction lines to output an alternating current signal.

6. The friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: A moving magnet (51) is embedded in the lower horizontal moving rack (47), which forms a mutually repulsive magnetic dipole with a fixed magnet (28) in a moving magnet support (29) in the static module (3), providing a non-linear restoring force for the energy harvesting device, broadening the working bandwidth of the system, and improving the output power.

7. A friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: Tensile bosses are designed on both the inner and outer sides of the rotating friction gear (42) meshing with the lower horizontal moving rack (47), and copper thin films are uniformly pasted on the tensile bosses.

8. A friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: As a driven member, the upper moving iron electromagnetic power generation module is not designed with a tension-compression spring.

9. A friction-magnetic array composite energy harvester device based on magnetic bistability according to claim 1, characterized in that: The energy conditioning module (1) includes a tribogenerator input interface (63), a moving-iron electromagnetic generator input interface (64), a rectifier circuit (60), direct current electricity (61), and an electrolytic capacitor (62). The tribo-moving-iron electromagnetic power generation module (2) is respectively connected to the tribogenerator input interface (63) and the moving-iron electromagnetic generator input interface (64). The two interfaces input the received electrical signals into the rectifier circuit (60). This circuit converts the alternating current electrical signal into a direct current electrical signal and then inputs it into the electrolytic capacitor (62) for storage, and finally provides a stable energy source for low-power-consuming devices such as sensors.

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