Magnetic-force-electric coupling energy harvester and method based on asymmetric torsional mode

Abstract

The application relates to a magnetic-force-electric coupling energy collector and method based on an asymmetric torsional mode, and belongs to the technical field of energy collection. The application comprises a piezoelectric sheet, an asymmetric bending beam structure, a mass block and a fixing screw rod; the polarization direction of the piezoelectric sheet is arranged along the thickness direction, and electrode coatings are arranged on both sides of the piezoelectric sheet along the thickness direction; the electrode coatings on both sides are defined as an adhesive electrode surface and a lead-out electrode surface respectively; the asymmetric bending beam structure comprises a main beam, a long limb and a short limb arranged in an integrated structure; the middle part of the main beam is provided with a fixing hole; the adhesive electrode surface is fixedly connected with the main beam through epoxy resin and is distributed on the left and right sides of the fixing hole; the lead-out electrode surface leads out electric signals through a wire; the mass block is fixed on the asymmetric bending beam structure through magnetic force; one end of the fixing screw rod is connected with the fixing hole; and the fixing screw rod is installed on a rigid base.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy harvesting devices, and particularly relates to a magnetic-force-electric coupling energy harvester and method based on asymmetric torsional mode. BACKGROUND

[0002] In recent years, with the continuous progress of Internet of Things technology and digital system integration technology, small wireless sensing devices, portable electronic devices and small wearable devices have developed rapidly. At present, these micro electronic devices generally rely on non-clean energy such as chemical batteries for power supply, and the replacement of the battery will increase the use cost of the device. Therefore, the energy harvesting technology of collecting clean energy such as thermal energy, light energy, magnetic energy and mechanical vibration from the natural environment has become a research hotspot. Among the many renewable energies, the energy harvesting technology of ubiquitous mechanical vibration energy and stray magnetic field energy with a frequency of 50 / 60 Hz around the power cable has attracted widespread attention, which is not limited by region, time and weather, and widely exists in infrastructure, electronic devices and factory construction scenes. The magnetic-force-electric coupling energy harvester can couple vibration energy and stray magnetic field energy. Compared with single energy harvesting technology, it has the advantages of diverse application scenarios, high energy density, convenient integration and wide application prospect.

[0003] Two Chinese invention patents with publication numbers CN112187098A and CN117277868A, "A multi-directional wide-band piezoelectric energy harvester" and "A multi-layer cascaded magnetic-force-electric magnetic field energy harvester and its manufacturing method", explain the current technical solutions in the field of magnetic-force-electric coupling energy harvesters. The mainstream magnetic-force-electric coupling energy harvesters on the market are mostly designed with a single-end clamping cantilever beam structure. When collecting vibration energy, the vibration signal is applied to the clamping end of the cantilever beam structure, and the permanent magnet mass at the free end of the cantilever beam drives the cantilever beam to complete the tensile bending deformation process, which makes the piezoelectric material work in the tensile bending mode, i.e. the length direction completes the stretching and contraction deformation, and the thickness direction generates electric charge. By collecting the electric charge signal on the surface of the piezoelectric sheet, the force-electric conversion process can be completed; when collecting magnetic field energy, the alternating magnetic field signal acts on the permanent magnet at the free end of the cantilever beam. Due to the angle between the direction of the alternating magnetic field and the magnetization direction of the permanent magnet, the permanent magnet will be subjected to alternating magnetic force, which will cause the cantilever beam end to generate a magnetic torque. The magnetic torque will drive the cantilever beam to complete the tensile bending deformation process, which makes the piezoelectric material in the tensile bending mode. By collecting the electric charge signal on the surface of the piezoelectric sheet, the magnetic-electric conversion process can be completed.

[0004] The energy collector composed of the traditional single-end clamping cantilever beam structure only utilizes the deformation in the length direction of the piezoelectric material, which is difficult to achieve high power output. The output current is only microamperes, and the output power density is only microwatts, which is particularly limited in industrial practical applications. At the same time, in the energy harvesting process, the traditional single-end clamping cantilever beam structure energy collector is often accompanied by clamping loss, which will lead to lower energy harvesting efficiency. The vibration mode of the traditional cantilever beam structure is mainly based on the first or second order bending mode in the length direction, and compared with the asymmetrically bent beam, the space occupation in the length direction is also larger, which is not conducive to installation and use in narrow space. In addition, the structure also has the problems of single resonant frequency point and narrow output bandwidth, which leads to the difficulty in achieving the resonant state in practical applications, and further reduces the energy output efficiency. When the mainstream multi-beam broadband energy collector is electrically connected in series and parallel, there is a phase difference between different signals, which will lead to the mutual offset of positive and negative charges and reduce the output power. This not only hinders the development of the magnetic-force-electric energy collector to the output broadband, but also increases the challenge of building a more compact and miniaturized structure. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned deficiencies in the prior art, and to provide a magnetic-force-electric coupling energy collector and method based on asymmetric torsional mode with reasonable structure design, so as to overcome the problems of low energy harvesting efficiency, low output power density, narrow output bandwidth, non-compact structure and difficulty in miniaturization to adapt to limited local space in the prior art.

[0006] The technical scheme adopted by the present application to solve the above problems is: the magnetic-force-electric coupling energy collector based on the asymmetric torsional mode, which is characterized in that: it comprises piezoelectric sheets with the same or opposite polarization directions to realize the series or parallel connection of electrical signals, can make the piezoelectric sheets work in the torsional mode to realize the asymmetric bending beam structure of energy output power, a mass block for realizing energy collection, and a fixing screw for mounting the asymmetric bending beam structure on a rigid base; the polarization direction of the piezoelectric sheet is arranged along the thickness direction, and electrode coatings are arranged on both sides of the piezoelectric sheet along the thickness direction, and the electrode coatings on both sides are defined as the bonding electrode surface and the lead-out electrode surface, respectively; the asymmetric bending beam structure comprises a main beam, a long limb and a short limb arranged in an integrated structure, the middle part of the main beam is provided with a fixing hole, the bonding electrode surface is bonded and fixed with the main beam through epoxy resin and is distributed on the left and right sides of the fixing hole, the lead-out electrode surface leads out the electrical signal through a wire, the mass block is fixed on the asymmetric bending beam structure through magnetic force, one end of the fixing screw is connected with the fixing hole, and the fixing screw is mounted on the rigid base. The setting position and number of the piezoelectric sheet can be configured according to the service scene requirements, and the number of the mass block can be designed in different directions according to the service scene requirements, so as to realize the application flexibility of the energy collector unit.

[0007] Further, the material of the piezoelectric sheet is lead zirconate titanate (PZT) piezoelectric ceramic, bismuth scandate-lead titanate (BS-PT) piezoelectric ceramic, barium titanate (BaTiO3) piezoelectric ceramic, potassium sodium niobate (KNN) piezoelectric ceramic, and lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal or lead zinc niobate-lead titanate (PZN-PT) piezoelectric single crystal material. The material of the selected piezoelectric sheet includes but is not limited to the above.

[0008] Further, the mass block adopts a metal block or a permanent magnet, wherein the N and S poles of the permanent magnet are connected in opposite directions and are fixed at the ends of the long limb and the short limb through the magnetic force therebetween. The designed position of the mass block can be flexibly changed, which can adjust the resonant frequency of the energy collector without changing the asymmetric bending beam structure; and according to the needs of the service scene, the magnetization direction of the magnet is reasonably adjusted to meet the energy collection needs of different service scenes, which improves the flexibility of the energy collector and the adaptability to the service scene.

[0009] Further, the asymmetric bending beam structure refers to a beam structure that is asymmetrically bent or folded in the length direction thereof, and is made of beryllium bronze or stainless steel with a material having a high elastic modulus. The design can change the stress distribution, deformation characteristics and vibration mode of the beam, so that the piezoelectric sheet is in a torsional mode under the excitation of a vibration source, which helps to improve the output power of the energy harvester; the design of different asymmetric bending beam structures can change the direction of the principal stress, thereby diversifying the torsional mode of the piezoelectric sheet; in addition, the asymmetric bending beam structure design adopts a torsional vibration mode, and the length size is smaller than that of a traditional cantilever beam structure, which also helps to miniaturize the device and ensure that the energy harvester unit works effectively and efficiently within a predetermined space range.

[0010] Further, one end of the fixing screw passes through the fixing hole and fixes the asymmetric bending beam structure by a point clamping method, and the other end of the fixing screw is fixed on the rigid base. During the magnetic-electric or force-electric conversion process of the energy harvester unit, the bending beam structures on the left and right sides of the fixing screw are under opposite torques, so that the fixing center remains nearly stationary, which maximizes the energy loss caused by the clamping loss.

[0011] Further, the main beam, long limb and short limb are arranged in a rectangular or trapezoidal structure.

[0012] Further, the piezoelectric sheet is arranged in a square or circular structure.

[0013] A working method of a magnetic-force-electric coupling energy harvester based on an asymmetric torsional mode, when the energy harvester is subjected to periodic torsional deformation of the asymmetric bending beam structure under external vibration signals or magnetic field signals, the piezoelectric sheet will also be subjected to periodic deformation, and the piezoelectric sheet will generate a periodic electrical signal on the surface based on the piezoelectric effect of the piezoelectric material; when the excitation frequency of the external vibration signal or magnetic field signal is consistent with the natural resonance frequency of the energy harvester, the vibration signal generated thereby is the largest, and the energy collection will be more effective, thereby achieving higher energy conversion efficiency and output power.

[0014] Further, when the energy collector is in a force-electricity conversion service scenario, according to the frequency of the external vibration signal, a long limb co-oscillation mode and a short limb co-oscillation mode can be excited, that is, two long limb parts vibrate up and down at the same time and two short limb parts vibrate up and down at the same time, which ensures that the phase difference between the alternating electrical signals of the piezoelectric sheet is fixed at zero; when the energy collector is in a magnetic-electricity conversion service scenario, according to the frequency of the external alternating magnetic field, a long limb reverse oscillation mode and a short limb reverse oscillation mode can be excited, that is, two long limb parts vibrate up and down alternately and two short limb parts vibrate up and down alternately, which ensures that the phase difference between the alternating electrical signals of the piezoelectric sheet is fixed at half a period. Whether the energy collector is in a co-oscillation mode in a force-electricity conversion service scenario or in a reverse oscillation mode in a magnetic-electricity conversion service scenario, the series-parallel connection of the electrical signals is more conducive to circuit design due to the fixed phase difference.

[0015] Further, when the energy collector works in a multi-unit matrix form, it includes a plurality of independently working energy collectors arranged in a matrix form, each of which can collect energy according to different magnetic-electricity conversion and force-electricity conversion service requirements, further adapting to the requirement of wideband energy collection. Through matrix layout, multiple energy collector units can be efficiently integrated, significantly reducing the size of the energy collector in terms of space occupation, which is particularly suitable for scenes with narrow layout space; and this matrix design makes the function modularly expandable according to the scene requirements, facilitating later maintenance and upgrading.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] 1. The asymmetrically bent beam structure in the energy collector changes the traditional mode of stress bearing of the piezoelectric sheet, which is no longer limited to a single length strain direction, but realizes the coupling of length and thickness normal strain directions and shear directions; therefore, the deformation of the piezoelectric sheet is not limited to the normal strain direction, and the deformation in the shear direction is also effectively utilized; further ensuring that the asymmetrically bent beam structure can fully utilize the torsional mode of the piezoelectric sheet, thereby significantly enhancing the output power of the energy collector.

[0018] 2. The fixed screw is fixed on the rigid base through the fixed hole in the center of the asymmetrically bent beam structure and cooperates with the bolt; during the magnetic-electricity conversion process of the energy collector unit, the cantilever beam structure on the left and right sides of the fixed screw keeps the fixed center nearly stationary under opposite magnetic torques, which maximizes the energy loss caused by clamping loss.

[0019] 3. The piezoelectric sheet is arranged in multiple positions, and the polarization direction of the piezoelectric sheet can be inconsistent, which can conveniently complete the electrical series and electrical parallel of the piezoelectric sheet; whether it is a same direction vibration mode serving in a force-electric conversion scene or a reverse vibration mode serving in a magnetic-electric conversion scene, the series and parallel of the electrical signal will greatly reduce the operation difficulty due to the fixed phase difference; therefore, according to different application scene requirements, a larger output current can be obtained through electrical parallel, or a larger output voltage can be obtained through electrical series, further improving the use flexibility and reliability of the series and parallel of the energy collector.

[0020] 4. The energy collector is multiple, and when multiple energy collectors work in a multi-unit matrix form, thanks to the compact structure design, the characteristic design of each energy collector unit can be realized through matrix arrangement, each unit can finely adjust the output frequency and output power according to the actual application scene, and various output bandwidth requirements can be fully met; in addition, thanks to the matrix layout characteristics, the function of the energy collector can be modularly expanded and conveniently maintained and upgraded according to user requirements, which embodies excellent flexibility and scalability. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structure schematic diagram of a magnetic-force-electric coupling energy collector based on an asymmetric torsional mode of embodiments 1 and 2 of the present application.

[0022] Figure 2 is a structure schematic diagram of an asymmetric bending beam structure (rectangular) of embodiments 1 and 2 of the present application.

[0023] Figure 3 is a long-limb same direction vibration mode schematic diagram of embodiment 1 of the present application.

[0024] Figure 4 is a short-limb same direction vibration mode schematic diagram of embodiment 1 of the present application.

[0025] Figure 5 is a structure schematic diagram of an asymmetric bending beam structure (trapezoidal) of embodiments 1 and 2 of the present application.

[0026] Figure 6 is a structure schematic diagram when multiple energy collectors are arranged in a 5x5 matrix of embodiments 1 and 2 of the present application.

[0027] Figure 7 is a long-limb reverse vibration mode schematic diagram of embodiment 2 of the present application.

[0028] Figure 8 is a short-limb reverse vibration mode schematic diagram of embodiment 2 of the present application.

[0029] In the diagram: piezoelectric element 101, asymmetric bent beam structure 102, mass block 103, fixing screw 104.

[0030] Main beam 201, long limb 202, short limb 203. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] Example 1 (e.g.) Figures 1-6 As shown in the figure, this energy harvester is a force-electric coupling energy harvester, which is used in force-electric conversion scenarios.

[0034] The magnetic-force-electric coupling energy harvester based on asymmetric torsional mode in this embodiment includes a piezoelectric sheet 101 with polarization directions in the same or opposite directions to realize series or parallel connection of electrical signals, an asymmetric bending beam structure 102 that enables the piezoelectric sheet 101 to work in torsional mode to realize energy output power, a mass block 103 for realizing energy harvesting, and a fixing screw 104 for mounting the asymmetric bending beam structure 102 on a rigid base.

[0035] The piezoelectric sheet 101 in the embodiment is provided in a square or circular structure, the polarization direction of the piezoelectric sheet 101 is provided along the thickness direction, and electrode coatings are provided on both sides of the piezoelectric sheet 101 along the thickness direction, defining the electrode coatings on both sides as the bonding electrode surface and the lead-out electrode surface, the asymmetric bending beam structure 102 includes a main beam 201, a long limb 202 and a short limb 203 provided in an integrated structure, the middle part of the main beam 201 is provided with a fixing hole, and the main beam 201, the long limb 202 and the short limb 203 are provided in a rectangular or trapezoidal structure.

[0036] The bonding electrode surface in the embodiment is fixed by epoxy resin and the main beam 201, and is distributed on the left and right sides of the fixing hole, the lead-out electrode surface leads out the electrical signal through the wire, the mass block 103 is fixed on the asymmetric bending beam structure 102 by magnetic force, one end of the fixed screw rod 104 is connected with the fixing hole, and the fixed screw rod 104 is installed on the rigid base.

[0037] The material of the piezoelectric sheet 101 in the embodiment is lead zirconate titanate (PZT) piezoelectric ceramic, bismuth scandate-lead titanate (BS-PT) piezoelectric ceramic, barium titanate (BaTiO3) piezoelectric ceramic, potassium sodium niobate (KNN) piezoelectric ceramic, and lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal or lead zinc niobate-lead titanate (PZN-PT) piezoelectric single crystal material. The material of the piezoelectric sheet 101 includes but is not limited to the above.

[0038] The mass block 103 in the embodiment adopts a metal block or a permanent magnet, wherein the N and S poles of the permanent magnet are connected in opposite directions and are fixed at the ends of the long limb 202 and the short limb 203 by magnetic force therebetween. The designed position of the mass block 103 can be flexibly changed, which can adjust the resonant frequency of the energy harvester without changing the asymmetric bending beam structure 102; and according to the needs of the service situation, the magnetization direction of the magnet is reasonably adjusted to meet the energy harvesting needs of different service situations, which improves the flexibility and service situation adaptability of the energy harvester.

[0039] The asymmetrically bent beam structure 102 in this embodiment refers to a beam structure that is asymmetrically bent or folded in the length direction. The asymmetrically bent beam structure 102 is made of beryllium bronze or stainless steel, which has a high elastic modulus. This design can change the stress distribution, deformation characteristics and vibration mode of the beam, so that the piezoelectric sheet 101 is in a torsional mode under the excitation of a vibration source, which helps to improve the output power of the energy harvester. Different designs of the asymmetrically bent beam structure 102 can change the direction of the principal stress, thereby diversifying the torsional mode of the piezoelectric sheet 101. In addition, the asymmetrically bent beam structure 102 design uses a torsional vibration mode, which has a smaller length than the traditional cantilever beam structure, and also helps to miniaturize the device, ensuring that the energy harvester unit works effectively and efficiently within a predetermined space range.

[0040] In this embodiment, one end of the fixed screw rod 104 passes through the fixing hole and fixes the asymmetrically bent beam structure 102 by point clamping. The other end of the fixed screw rod 104 is fixed on the rigid base. During the magnetic-electric or force-electric conversion process of the energy harvester unit, the bent beam structures on the left and right sides of the fixed screw rod are under opposite torques, which keeps the fixed center nearly stationary, thereby avoiding energy loss caused by clamping loss to the greatest extent.

[0041] In this embodiment, when the energy harvester is subjected to periodic torsional deformation of the asymmetrically bent beam structure 102 due to external vibration signals or magnetic field signals, it will induce periodic deformation of the piezoelectric sheet 101. Based on the positive piezoelectric effect principle of the piezoelectric material, the piezoelectric sheet 101 will generate a periodic electrical signal on the surface. When the excitation frequency of the external vibration signal or magnetic field signal is consistent with the natural resonant frequency of the energy harvester, the resulting vibration signal will be the largest, and the energy harvesting will be more effective, thereby achieving higher energy conversion efficiency and output power.

[0042] In this embodiment, when the energy harvester is in a force-electric conversion service scenario, different frequencies of external vibration signals can excite the long limbs 202 and the short limbs 203 to vibrate in the same direction, i.e., the two long limbs 202 vibrate up and down at the same time and the two short limbs 203 vibrate up and down at the same time, which ensures that the phase difference between the alternating electrical signals of the piezoelectric sheet 101 is fixed at zero. Whether it is a same direction vibration mode in a force-electric conversion service scenario or an opposite vibration mode in a magnetic-electric conversion service scenario, the series and parallel connection of the electrical signals will be easier to design due to the fixed phase difference.

[0043] In this embodiment, when the energy collector works in a multi-unit matrix form, it includes a plurality of independently working energy collectors arranged in a matrix form, each of which can collect energy according to different magnetic-electric conversion, force-electric conversion service scene requirements, and further adapt to the wide frequency energy collection requirements. Through matrix layout, multiple energy collector units can be efficiently integrated, significantly reducing the size of the energy collector in terms of space occupation, which is particularly suitable for scenes with narrow layout space; and this matrix design makes the function modularly expandable according to the scene requirements, facilitating later maintenance and upgrading.

[0044] Specifically, the energy collector serves in a force-electric conversion scene requirement, and its structural diagram is as shown in Figure 1 , which includes a piezoelectric sheet 101, an asymmetric bending beam structure 102, a mass block 103, and a fixed screw rod 104; as Figure 2 , two piezoelectric sheets 101 are bonded on the main beam 201 on both sides of the fixed hole of the asymmetric bending beam structure 102 using epoxy resin, and their polarization directions can be different or the same; when the vibration table signal acts on the energy collector, the asymmetric bending beam structure 102 applies an alternating torsional stress to the piezoelectric sheet 101, which generates an output electrical signal due to the positive piezoelectric effect, and the energy collector will have two resonance modes in the resonance state, as Figure 3 (long limb co-directional vibration mode) and Figure 4 (short limb co-directional vibration mode).

[0045] The size parameters of the main beam 201, the long limb 202, and the short limb 203 in the asymmetric bending beam structure 102 are flexible and rich, and can be flexibly selected according to actual application scenarios, as Figure 5 , the main beam 201, the long limb 202, and the short limb 203 can adopt a rectangular design, or a trapezoidal design or other shape structure design to plan stress distribution to adapt to different scene requirements; especially when the main beam 201 adopts a trapezoidal structure design, the end part will produce more uniform stress distribution, and compared with other structure designs, this design can give the energy collector higher energy conversion efficiency.

[0046] In order to effectively improve the energy collection efficiency and adapt to different task scene requirements, multiple energy collector units need to be used in cooperation, and here a 5x5 matrix arranged energy collector group is taken as an example. As Figure 6 , it is a 5x5 matrix arranged energy collector group, in which each energy collector unit can be independently controlled, so that the resonance frequency and working mode of the energy collector can be adjusted by designing energy collectors with different size parameters. For example Figure 3 long limb co-directional vibration mode and Figure 4short-limb co-oscillation mode. The asymmetrically bent beam structure 102 is designed to facilitate small size assembly and dense arrangement to meet the broadband requirement or improve the energy conversion efficiency in different scenarios; therefore the whole energy harvester matrix group has simple structure, regular arrangement, small volume and is easy to maintain, which is suitable for most energy harvesting scenarios.

[0047] Embodiment 2 (as shown in Figures 1-2 , 5-8), the energy harvester is a magnetic-electric coupling energy harvester, which serves in a magnetic-electric conversion scenario.

[0048] The magnetic-force-electric coupling energy harvester based on asymmetric torsional mode in the embodiment includes the piezoelectric sheet 101 with the same or opposite polarization direction to realize the series or parallel connection of the electrical signal, the piezoelectric sheet 101 working in the torsional mode to realize the asymmetric bent beam structure 102, the mass 103 for energy harvesting, and the fixing screw 104 for mounting the asymmetric bent beam structure 102 on the rigid base.

[0049] The piezoelectric sheet 101 in the embodiment is in square or circular structure, the polarization direction of the piezoelectric sheet 101 is along the thickness direction, and the electrode coating is arranged on both sides of the piezoelectric sheet 101 along the thickness direction, defining the electrode coating on both sides as the bonding electrode surface and the lead-out electrode surface, the asymmetric bent beam structure 102 includes the main beam 201, the long limb 202 and the short limb 203 arranged in an integrated structure, the middle part of the main beam 201 is provided with a fixing hole, and the main beam 201, the long limb 202 and the short limb 203 are arranged in a rectangular or trapezoidal structure.

[0050] The bonding electrode surface in the embodiment is bonded and fixed with the main beam 201 by epoxy resin and is distributed on the left and right sides of the fixing hole, the lead-out electrode surface leads out the electrical signal through the wire, the mass 103 is fixed on the asymmetric bent beam structure 102 by magnetic force, one end of the fixing screw 104 is connected with the fixing hole, and the fixing screw 104 is mounted on the rigid base.

[0051] The material of the piezoelectric sheet 101 in the embodiment is lead zirconate titanate (PZT) piezoelectric ceramic, bismuth scandate-lead titanate (BS-PT) piezoelectric ceramic, barium titanate (BaTiO3) piezoelectric ceramic, potassium sodium niobate (KNN) piezoelectric ceramic, and lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal or lead zinc niobate-lead titanate (PZN-PT) piezoelectric single crystal material. The material of the piezoelectric sheet 101 includes but is not limited to the above.

[0052] The mass 103 in the embodiment is a metal block or a permanent magnet, wherein the N and S poles of the permanent magnet are connected in opposite directions and fixed at the ends of the long limbs 202 and the short limbs 203 by the magnetic force therebetween. The position of the mass 103 can be flexibly changed, which can adjust the resonant frequency of the energy harvester without changing the asymmetrically bent beam structure 102; and the magnetization direction of the magnet can be reasonably adjusted according to the service situation to meet the energy harvesting requirements of different service situations, which improves the flexibility and service adaptability of the energy harvester.

[0053] The asymmetrically bent beam structure 102 in the embodiment refers to a beam structure that is asymmetrically bent or folded in the length direction. The asymmetrically bent beam structure 102 is made of beryllium bronze or stainless steel, which has a high elastic modulus. The design can change the stress distribution, deformation characteristics and vibration mode of the beam, so that the piezoelectric sheet 101 is in a torsional mode under the excitation of the vibration source, which helps to improve the output power of the energy harvester; the design of different asymmetrically bent beam structures 102 can change the direction of the principal stress, thereby diversifying the torsional mode of the piezoelectric sheet 101; in addition, the asymmetrically bent beam structure 102 design adopts a torsional vibration mode, which has a smaller length than the traditional cantilever beam structure, which also helps to miniaturize the device and ensure that the energy harvester unit works effectively and efficiently within a predetermined space range.

[0054] In the embodiment, one end of the fixed screw 104 passes through the fixing hole and fixes the asymmetrically bent beam structure 102 by point clamping, and the other end of the fixed screw 104 is fixed on the rigid base. During the magnetic-electric or force-electric conversion of the energy harvester unit, the bent beam structures on the left and right sides of the fixed screw are under opposite torques, which keeps the fixed center nearly stationary, which maximizes the energy loss caused by the clamping loss.

[0055] In the embodiment, when the energy harvester is subjected to periodic torsional deformation of the asymmetrically bent beam structure 102 due to external vibration signals or magnetic field signals, it will induce the piezoelectric sheet 101 to be periodically deformed. The piezoelectric sheet 101 will generate a periodic electrical signal on the surface based on the positive piezoelectric effect principle of the piezoelectric material; when the excitation frequency of the external vibration signal or magnetic field signal is consistent with the natural resonant frequency of the energy harvester, the vibration signal generated thereby is the largest, which will more effectively collect energy, thereby achieving higher energy conversion efficiency and output power.

[0056] In this embodiment, when the energy collector is in a magnetic-electric conversion service scenario, according to the different frequencies of the external alternating magnetic field, the long limbs 202 and the short limbs 203 can be excited to vibrate in reverse modes, that is, the two long limbs 202 vibrate up and down and the two short limbs 203 vibrate up and down, which ensures that the phase difference between the alternating electrical signals of the piezoelectric sheet 101 is fixed at half a period. Whether it is in a same direction vibration mode in a force-electric conversion scenario or in a reverse vibration mode in a magnetic-electric conversion scenario, the series and parallel connection of the electrical signals will be easier to design the circuit due to the fixed phase difference.

[0057] In this embodiment, when the energy collector works in a multi-unit matrix form, it includes a plurality of independently working energy collectors arranged in a matrix form, each of which can collect energy according to different magnetic-electric conversion and force-electric conversion service requirements, further adapting to the wideband energy collection requirement. Through the matrix layout, a plurality of energy collector units can be efficiently integrated, significantly reducing the size of the energy collector in terms of space occupation, which is particularly suitable for scenes with narrow layout space; and this matrix design makes the function modularly expandable according to the scene requirements, facilitating the later maintenance and upgrade.

[0058] Specifically, the energy collector serves the magnetic-electric conversion scenario requirement, and its structural diagram is shown in Figure 1 When the alternating magnetic field signal acts on the mass block 103 at the free end of the cantilever beam, the permanent magnet of the mass block 103 will be subjected to an alternating magnetic force due to the angle between the direction of the alternating magnetic field and the magnetization direction of the permanent magnet of the mass block 103, which will cause the end of the asymmetric bending beam structure 102 to generate a magnetic torque, which will drive it to complete the tension-bending deformation process, and the asymmetric bending beam structure 102 will apply an alternating torsional stress to the piezoelectric sheet 101, and due to the positive piezoelectric effect, an output electrical signal will be generated; the energy collector will have two resonance modes in the resonance state, as shown in Figure 7 (long limb reverse vibration mode) and Figure 8 (short limb reverse vibration mode).

[0059] The fixed screw rod 104 is fixed on the rigid base through the fixed hole of the asymmetric bending beam structure 102 and the bolt; during the magnetic-electric conversion process of the energy collector, the cantilever beam structures on the left and right sides of the fixed screw rod 104 are subjected to opposite magnetic torques, so that the fixed center remains nearly stationary, which maximizes the avoidance of clamping loss.

[0060] The shape of the piezoelectric sheet 101 has considerable flexibility in design, and is not limited to common square or circular forms. The internal structure also has diverse possibilities, and can be designed to include a perforated structure or a fully enclosed structure. By optimizing the shape of the piezoelectric sheet, the energy harvesting efficiency can be improved to some extent.

[0061] The piezoelectric sheet 101 can be arranged at multiple positions in the energy harvester, and the polarization direction of the piezoelectric sheet 101 can be inconsistent. This can facilitate the electrical series connection and electrical parallel connection of the piezoelectric sheet 101. According to different application scenarios, a larger output current can be obtained through electrical parallel connection, or a larger output voltage can be obtained through electrical series connection, further improving the flexibility of the energy harvester.

[0062] In summary, the magnetic-force-electric coupling energy harvester based on the asymmetric torsional mode utilizes the torsional mode of the piezoelectric sheet 101. During operation, the co-directional vibration mode of the long limb and the co-directional vibration mode of the short limb coexist with the reverse vibration mode of the long limb and the reverse vibration mode of the short limb, which makes the output signal larger. At the same time, based on the design concept of the asymmetric bending beam structure, the energy harvester has multiple service modes, and compared with the traditional cantilever beam type energy harvester, it has a significant wide frequency advantage in output performance.

[0063] In addition, during the magnetic-electric conversion process of the energy harvester unit, the cantilever beam structures on the left and right sides of the fixed screw under opposite magnetic torques keep the fixed center nearly stationary, which maximizes the avoidance of "clamping loss". Compared with the traditional single-end clamping cantilever beam type energy harvester, the output power of the energy harvester with this structure can be maximized.

[0064] Finally, whether it is the co-directional vibration mode serving in the force-electric conversion scenario or the reverse vibration mode serving in the magnetic-electric conversion scenario, the series-parallel connection of the electrical signal will greatly reduce the operation difficulty due to the fixed phase difference. Therefore, according to different application scenarios, a larger output current can be obtained through electrical parallel connection, or a larger output voltage can be obtained through electrical series connection, further improving the flexibility and reliability of the series-parallel connection of the energy harvester.

[0065] The use of high-performance piezoelectric single crystal materials can further improve the output power density. Independent energy harvester units can also be assembled in an array, further improving the flexibility of the energy harvester and broadening the application scenarios of the energy harvester.

[0066] In addition, it should be noted that the specific embodiments described in the specification, the shape of the components, the name taken, etc. can be different, the above described in the specification is only an example of the structure of the present application. Any equivalent changes or simple changes made in accordance with the structure, features and principles described in the patent concept of the present application are included in the protection scope of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as they do not deviate from the structure of the present application or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method for operating a magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional modes, characterized in that: The energy harvester includes piezoelectric sheets (101) with polarization directions in the same or opposite directions to achieve series or parallel connection of electrical signals; an asymmetric bent beam structure (102) that allows the piezoelectric sheet (101) to operate in torsion mode to achieve energy output power; a mass block (103) for energy harvesting; and a fixing screw (104) for mounting the asymmetric bent beam structure (102) on a rigid base. The polarization direction of the piezoelectric sheet (101) is set along the thickness direction, and electrode coatings are provided on both sides of the piezoelectric sheet (101) along the thickness direction to define the two sides. The electrode coatings are respectively the adhesive electrode surface and the output electrode surface. The asymmetric bending beam structure (102) includes a main beam (201), a long limb (202) and a short limb (203) with an integral structure. The main beam (201) has a fixing hole in the middle. The adhesive electrode surface is bonded and fixed to the main beam (201) with epoxy resin and is distributed on the left and right sides of the fixing hole. The output electrode surface leads out the electrical signal through the wire. The mass block (103) is fixed on the asymmetric bending beam structure (102) by magnetic force. One end of the fixing screw (104) is connected to the fixing hole. The energy harvester operates by: When the energy harvester undergoes periodic torsional deformation of the asymmetric bending beam structure (102) due to external vibration or magnetic field signals, it will induce periodic deformation of the piezoelectric sheet (101). Based on the principle of the positive piezoelectric effect unique to piezoelectric materials, the piezoelectric sheet (101) will generate periodic electrical signals on its surface. When the excitation frequency of the external vibration or magnetic field signal is consistent with the inherent resonant frequency of the energy harvester, the resulting vibration signal will be the largest. When the energy harvester is in the service scenario of force-to-electric conversion, it can excite the same-direction vibration mode of the long limb (202) and the same-direction vibration mode of the short limb (203) according to the different frequencies of the external vibration signal. That is, the two long limb (202) parts vibrate up and down at the same time and the two short limb (203) parts vibrate up and down at the same time. This ensures that the phase difference between the alternating electrical signals of the piezoelectric element (101) is fixed at zero. When the energy harvester is in the service scenario of magneto-electric conversion, it can excite the opposite vibration mode of the long limb (202) and the opposite vibration mode of the short limb (203) according to the different frequencies of the external alternating magnetic field. That is, the two long limb (202) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (203) parts vibrate up and down one and the two short limb (201 ...

2. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: The piezoelectric element (101) is made of lead zirconate titanate (PZT) piezoelectric ceramic, bismuth scandate-lead titanate (BS-PT) piezoelectric ceramic, barium titanate (BaTiO3) piezoelectric ceramic, potassium sodium niobate (KNN) piezoelectric ceramic, and lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal or lead zinc niobate-lead titanate (PZN-PT) piezoelectric single crystal material.

3. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: The mass block (103) is made of metal or permanent magnet, wherein the N and S poles of the permanent magnet are connected to each other and fixed to the ends of the long limb (202) and the short limb (203) by magnetic force between them.

4. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: The asymmetric bending beam structure (102) refers to a beam structure that undergoes asymmetric bending or folding in its length direction. The asymmetric bending beam structure (102) is made of beryllium bronze or stainless steel, which are materials with high elastic modulus.

5. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: One end of the fixing screw (104) passes through the fixing hole and fixes the asymmetric bending beam structure (102) by point clamping. The other end of the fixing screw (104) is fixed on the rigid base.

6. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: The main beam (201), long limb (202), and short limb (203) are arranged in a rectangular or trapezoidal structure.

7. The operating method of the magnetic-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: The piezoelectric element (101) is arranged in a square or circular structure.

8. The operating method of the magnetic-mechanical-electric coupling energy harvester based on asymmetric torsional mode according to claim 1, characterized in that: When the energy harvester operates in a multi-unit matrix configuration, it comprises multiple independently operating energy harvesters arranged in a matrix. Each of these independently operating energy harvesters can harvest energy according to different magneto-electric conversion and force-electric conversion service scenarios, further adapting to broadband energy harvesting requirements.

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