Broadband vibration energy collection device and method based on multistage vibration energy coupling
Through multi-stage vibration energy coupling structure and dynamic impedance matching technology, the problem of instability of the electrical energy output of traditional vibration energy collectors at different frequencies is solved, and efficient energy capture in the wideband is achieved.
Patent Information
- Application Number
- CN202510606233.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-12
- Publication Date
- 2025-08-05
AI Technical Summary
Traditional vibration energy collectors can only collect high-power electrical energy at specific frequencies, making it difficult to adapt to the changes in vibration frequency at different vehicle driving speeds, resulting in unstable output electrical power under different working conditions.
The multi-stage vibration energy coupling structure is adopted, and the resonant frequencies of each level of elastic structure are designed to be different through the multi-stage frequency coupling chain and dynamic impedance matching technology. The resonant frequencies of each level of elastic structure are combined with electromagnetic and piezoelectric composite materials to achieve cross-band energy capture.
The ultra-wideband energy capture is achieved under a compact structure, which improves energy density, space efficiency and working conditions adaptability, and improves energy coupling efficiency.
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Figure CN120433628A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of vibration energy capture, and in particular to a wide-band vibration energy collection device and method based on multi-level vibration energy coupling. Background Art
[0002] Ambient energy harvesting technology is a technology that converts the energy widely present in the surrounding environment, such as solar energy, wind energy, tidal energy, vibration energy, etc., into electrical energy for storage and use through energy collectors.
[0003] In many cases, it's impractical and uneconomical to power sensor nodes deployed in remote areas using cables. If batteries are used, large-scale battery replacement becomes difficult. Therefore, power supply issues have become a pressing challenge in the development of wireless sensors.
[0004] Environmental energy harvesting technologies primarily include solar energy, wind energy, and vibration energy harvesting, each with its own advantages and disadvantages. Solar energy harvesting, based on the theory of photovoltaic power generation, utilizes semiconductor electronic devices to convert solar energy into electricity. While offering numerous advantages, such as safety, reliability, and easy energy acquisition, it is significantly affected by weather conditions, and because the energy harvested is proportional to its surface area, miniaturization is difficult. Wind energy harvesting, utilizing wind turbines and generators to convert wind energy into electricity, offers advantages such as pollution-free operation and widespread distribution. However, it suffers from limitations such as low energy density, regional disparities, and energy stability. Vibration energy harvesting, using specialized mechanical structures or materials to collect vibration energy from the natural environment and convert it into electricity, offers advantages such as pollution-free operation and low cost, making it a key area of research in energy supply. Industrial vibration energy has the highest harvestable power.
[0005] Common methods for converting vibration energy into electrical energy fall into three categories: electrostatic vibration energy harvesting, electromagnetic vibration energy harvesting, and piezoelectric vibration energy harvesting. Electrostatic vibration energy harvesting primarily consists of an external power source, a variable capacitor, and a resonant system. Its principle is that under the action of an external power source, the variable capacitor generates an induced charge. When the capacitor's capacitance changes, the charge within the capacitor redistributes, forming a loop current, thereby converting vibration energy into electrical energy. Electromagnetic vibration energy harvesting primarily consists of coils, magnets, springs, and other components. Its operating principle is that relative motion between the magnet and coil changes the magnetic flux within the coil, generating an induced current, thereby converting vibration energy into electrical energy. The core structure of piezoelectric vibration energy harvesting is a piezoelectric material. When stimulated by a vibration source, the piezoelectric material also vibrates and deforms. Due to the positive piezoelectric effect, a potential difference is formed between the electrodes at both ends of the piezoelectric material, converting vibration energy into electrical energy.
[0006] Existing technology and its shortcomings:
[0007] There is a problem with vibration energy harvesting, that is, high-power electrical energy can only be harvested under specific frequency vibration (the natural vibration frequency of the energy harvester). If it deviates from this frequency, the device's energy harvesting ability will be greatly reduced.
[0008] However, vehicles typically travel at varying speeds, with the vibration frequencies generated by the vehicle varying between low and high speeds. Consequently, conventional vibration energy harvesters struggle to achieve high output power at varying vehicle speeds. Summary of the Invention
[0009] To solve the above problems, the present invention aims to propose a wide-band vibration energy harvesting device based on multi-level vibration energy coupling. Through the deep integration of multi-level frequency coupling chain and dynamic impedance matching technology, ultra-wide-band energy capture can be achieved while maintaining a compact structure. Its energy density, spatial efficiency and working condition adaptability have reached leading levels, achieving higher energy coupling efficiency.
[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:
[0011] A broadband vibration energy harvesting device based on multi-level vibration energy coupling, comprising:
[0012] an energy collector body for converting mechanical vibration energy into electrical energy;
[0013] A multi-stage vibration energy coupling structure is connected in series between the energy collector body and the vibration source to be measured;
[0014] The multi-stage vibration energy coupling structure includes at least two elastic structure groups, each elastic structure group includes at least two elastic structures and at least one intermediate fixed structure, the intermediate fixed structure is connected between the two elastic structures, and the two elastic structures are respectively connected to the energy collector body and the vibration source to be measured;
[0015] The resonant frequencies of the intermediate fixed structures of each level of elastic structure group are different and are set as target vibration coupling frequency segments.
[0016] Furthermore, the resonant frequency of the intermediate fixed structure is set to 5-20 Hz in the low frequency band and 20-120 Hz in the high frequency band; the stiffness gradient ratio of the elastic structure satisfies K n+1 / K n =0.6~1.5, used to achieve cross-band mechanical impedance matching.
[0017] Furthermore, the elastic structure adopts an asymmetric spring or an elastic beam with a gradient cross-section.
[0018] Furthermore, the elastic beam with a gradual cross-section is arranged on the vibration transmission path.
[0019] Furthermore, the intermediate fixed connection structure adopts a bistable spring design.
[0020] Furthermore, the energy collector body comprises a composite energy conversion unit:
[0021] Low frequency band (5-20Hz): uses electromagnetic power generation components, including NdFeB permanent magnets and 3D printed micro coils;
[0022] Medium and high frequency band (20-120Hz): piezoelectric composite materials are used.
[0023] In order to achieve the above objectives, the present invention further provides a collection method of a broadband vibration energy collection device based on multi-level vibration energy coupling, comprising:
[0024] Step S1: coupling broadband vibration energy to the target frequency band step by step through a multi-stage elastic structure group;
[0025] Step S2: Exciting resonance amplification at the middle fixed structure;
[0026] Step S3: using a gradient stiffness elastic structure to achieve cross-band impedance matching;
[0027] Step S4: Efficiently generate electricity in different frequency bands through a composite energy conversion unit.
[0028] Beneficial effects: The present invention achieves ultra-wideband energy capture while maintaining a compact structure through the deep integration of multi-stage frequency coupling chain and dynamic impedance matching technology. Its energy density, spatial efficiency and working condition adaptability all reach leading levels, achieving higher energy coupling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:
[0030] Figure 1 This is a schematic diagram of the frequency distribution of vibration energy generated by the vehicle under different driving speed conditions;
[0031] Figure 2 Schematic diagram of energy harvester array with different resonant frequencies;
[0032] Figure 3 Schematic diagram of the installation of traditional energy harvester;
[0033] Figure 4 Schematic diagram of the structure of a broadband vibration energy harvesting device (two-stage elastic structure) based on multi-stage vibration energy coupling according to an embodiment of the present invention;
[0034] Figure 5 Schematic diagram of the structure of a broadband vibration energy harvesting device (three-stage elastic structure) based on multi-stage vibration energy coupling according to an embodiment of the present invention;
[0035] Figure 6 Schematic diagram of vibration energy coupling. DETAILED DESCRIPTION
[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.
[0037] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.
[0038] Figure 1 The frequency distribution diagram of the vibration energy generated by the vehicle during low, medium and high speed driving is given. It can be seen that when the vehicle travels at different speeds, the frequency range of the environmental vibration generated by the vehicle is relatively wide, and the frequency generated under different road conditions also varies. In order to solve the problem of collecting broadband environmental vibration energy, the traditional solution is to design the vibration environment energy harvester into multiple independent energy harvester arrays with different resonant frequencies, such as Figure 2 As shown, the resonant frequency of each energy harvester in the array is different, and the frequencies of all energy harvesters in the array are distributed within the wide frequency range of the ambient vibration energy, thereby achieving wide coverage of the ambient vibration energy frequency. However, there is a problem with this design method. Under the current working state, only one energy harvester in the array can be in the optimal working state, that is, the state of maximum energy collection and power generation, while the other energy harvesters in the array are in an inefficient power generation state, which greatly wastes the area of the energy harvester and the effective power generation efficiency.
[0039] To solve this problem and achieve the most efficient collection of environmental vibration energy under the same size conditions, we have developed a wide-band vibration energy harvesting device and method based on multi-level vibration energy coupling.
[0040] Example 1
[0041] Based on this, see Figure 3-6 : A broadband vibration energy harvesting device based on multi-level vibration energy coupling, comprising:
[0042] The energy collector body 1 is used to convert mechanical vibration energy into electrical energy;
[0043] The multi-stage vibration energy coupling structure 2 is connected in series between the energy collector body 1 and the vibration source 3 to be measured;
[0044] The multi-stage vibration energy coupling structure 2 includes at least two elastic structure groups 21. Each elastic structure group 21 includes at least two elastic structures 211 and at least one intermediate fixed structure 212. The intermediate fixed structure 212 is connected between the two elastic structures 211. The two elastic structures 211 are respectively connected to the energy collector body 1 and the vibration source 3 to be measured.
[0045] The resonant frequencies of the intermediate fixed structures 212 of the elastic structure groups 21 of each level are different and are set to the target vibration coupling frequency range.
[0046] This embodiment achieves ultra-wideband energy capture while maintaining a compact structure through the deep integration of multi-stage frequency coupling chains and dynamic impedance matching technology. Its energy density, spatial efficiency and working condition adaptability all reach leading levels, achieving higher energy coupling efficiency.
[0047] In a specific example, the resonant frequency of the intermediate fixed structure 212 is set to 5-20 Hz in the low frequency band and 20-120 Hz in the high frequency band; the stiffness gradient ratio of the elastic structure 211 satisfies K n+1 / K n =0.6~1.5, used to achieve cross-band mechanical impedance matching.
[0048] Broadband coverage:
[0049] By connecting multiple elastic structure groups (5-20Hz low frequency band, 20-120Hz high frequency band) in series, it covers 5-120Hz wide-band vibration energy capture, breaking through the bandwidth limitation of traditional single-stage structure.
[0050] Impedance matching optimization:
[0051] Elastic structure stiffness gradient ratio (K n+1 / K n =0.6~1.5) to achieve cross-band mechanical impedance matching and reduce energy reflection loss.
[0052] In a specific example, the elastic structure 211 adopts an asymmetric spring or a gradient cross-section elastic beam, and its stiffness changes according to an exponential law along the vibration transmission direction:
[0053] K(x)=K0·e αX (α=0.1-0.3 / mm), where x is the coordinate of the vibration transmission direction and K0 is the initial stiffness value.
[0054] Nonlinear stiffness design: The exponentially varying stiffness of asymmetric springs or elastic beams with tapered cross-sections enhances low-frequency vibration energy capture capabilities (low-frequency efficiency increased by ≥30%).
[0055] Energy transfer efficiency: The gradient change of stiffness suppresses the reflection of vibration waves, and the energy transfer efficiency is ≥85% (traditional structure <60%).
[0056] In a specific example, the elastic beam with a gradual cross-section is arranged on the vibration transmission path, and the change rate of its cross-sectional thickness satisfies:
[0057] h(x)=h0·(1+βx) (β=0.12-0.15 / mm).
[0058] The elastic beam with a tapered cross-section in this embodiment can be used to suppress vibration wave reflection, and the energy transfer efficiency is ≥85%.
[0059] In a specific example, the intermediate connection structure 212 adopts a bistable spring design, and its potential energy function satisfies:
[0060]
[0061] Where λ is the nonlinear coefficient, and the critical trigger energy threshold is ≤0.1mJ.
[0062] Nonlinear resonance amplification: The bistable spring potential energy function introduces a potential energy well effect to stimulate subharmonic resonance.
[0063] Low-amplitude adaptability: The critical trigger energy threshold is ≤0.1mJ, and weak vibrations with amplitudes as low as 0.05mm can be captured.
[0064] In a specific example, the energy collector body 1 comprises a composite energy conversion unit:
[0065] Low frequency band (5-20Hz): uses electromagnetic power generation components, including NdFeB permanent magnets and 3D printed micro coils;
[0066] Medium and high frequency band (20-120Hz): piezoelectric composite materials are used, and their piezoelectric constant d 33 ≥650pC / N.
[0067] Efficient conversion of frequency bands:
[0068] Low-frequency electromagnetic power generation: NdFeB permanent magnets combined with 3D-printed microcoils, with a conversion efficiency of ≥25% in the low-frequency band (5-20Hz);
[0069] Medium and high frequency piezoelectric power generation: Interdigitated piezoelectric composite materials with a power density of ≥32μW / mm in the medium and high frequency band (20-120Hz) 3 .
[0070] like Figure 6As shown, through design, the resonant frequency of the middle fixed structure of the elastic structure of the two-stage elastic structure can be made to be vibration coupling energy frequency 1, and the resonant frequency of the other middle fixed structure of the two-stage elastic structure can be made to be vibration coupling energy frequency 2. When the vibration frequency generated by the object whose energy is being collected is low frequency, the vibration energy coupling structure couples part of the energy to the vibration coupling energy frequency 1 through vibration coupling, causing the middle fixed structure to vibrate. By reducing the damping of the middle fixed structure, it is even possible to achieve amplification (resonance) of the coupled vibration energy. The environmental vibration energy coupled to the middle fixed structure is then coupled to the vibration frequency of the environmental energy collector through the elastic structure. Similarly, when the vibration frequency generated by the object whose energy is being collected is high frequency, the vibration energy coupling structure couples part of the energy to the vibration coupling energy frequency 2 through vibration coupling, causing the other middle fixed structure to vibrate. By reducing the damping of the other middle fixed structure, it is even possible to achieve amplification (resonance) of the coupled vibration energy. The environmental vibration energy coupled to the other middle fixed structure is then coupled to the vibration frequency of the environmental energy collector through the elastic structure.
[0071] The multi-stage vibration energy coupling structure of this embodiment works as follows:
[0072] Frequency band classification and multimodal collaboration
[0073] Frequency band coverage mechanism
[0074] Multi-stage elastic structure groups (such as springs and cantilever beams) are designed according to frequency bands, with each stage corresponding to a specific resonant frequency (such as 5-20Hz low frequency, 20-60Hz medium frequency, and 60-120Hz high frequency), covering a wide bandwidth of vibration energy through series coupling;
[0075] The elastic structure stiffness gradient ratio optimizes mechanical impedance matching and reduces energy reflection loss (reflectivity < 8%)
[0076] Multimodal energy transfer
[0077] The intermediate fixed structure (such as a bistable spring or magnet coupling) excites the normal vibration mode, promoting the periodic transfer of energy between different modes and realizing cross-band energy transfer.
[0078] Nonlinear coupling and dynamic regulation
[0079] Nonlinear resonance amplification
[0080] The nonlinear design of the bistable spring or magnet introduces a potential energy well effect, triggering subharmonic resonance and improving the capture efficiency of low-amplitude vibrations;
[0081] Active damping control
[0082] The composite actuator based on magnetorheological fluid and shape memory alloy adjusts the damping coefficient in real time, dynamically matches the main frequency of environmental vibration with the structural resonant frequency, and extends the effective bandwidth to ≥15Hz.
[0083] Example 2
[0084] To achieve the above objectives, this embodiment further provides a collection method of a broadband vibration energy collection device based on multi-level vibration energy coupling, comprising:
[0085] Step S1: coupling broadband vibration energy to the target frequency band step by step through the multi-stage elastic structure group 21;
[0086] Step S2: Excite resonance amplification at the intermediate fixed structure 212;
[0087] Step S3: using the elastic structure 211 with gradient stiffness to achieve cross-band impedance matching;
[0088] Step S4: Efficiently generate electricity in different frequency bands through a composite energy conversion unit.
[0089] The collection method of the wide-band vibration energy collection device based on multi-stage vibration energy coupling in this embodiment has the same advantages as the above-mentioned wide-band vibration energy collection device based on multi-stage vibration energy coupling over the prior art, and will not be repeated here.
[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A broadband vibration energy harvesting device based on multi-level vibration energy coupling, characterized in that: include: An energy collector body (1) for converting mechanical vibration energy into electrical energy; A multi-stage vibration energy coupling structure (2) is connected in series between the energy collector body (1) and the vibration source to be measured (3); The multi-stage vibration energy coupling structure (2) includes at least two elastic structure groups (21), each elastic structure group (21) includes at least two elastic structures (211) and at least one intermediate fixed connection structure (212), the intermediate fixed connection structure (212) is connected between the two elastic structures (211), and the two elastic structures (211) are respectively connected to the energy collector body (1) and the measured vibration source (3); The resonance frequencies of the intermediate fixed connection structures (212) of each level of elastic structure group (21) are all different and are set to target vibration coupling frequency segments.
2. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 1, characterized in that: The resonant frequency of the intermediate fixed structure (212) is set to 5-20 Hz in the low frequency band and 20-120 Hz in the high frequency band; the stiffness gradient ratio of the elastic structure (211) satisfies K n+1 / K n =0.6~1.5, used to achieve cross-band mechanical impedance matching.
3. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 2, characterized in that: The elastic structure (211) adopts an asymmetric spring or an elastic beam with a gradually changing cross-section.
4. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 2, characterized in that: The intermediate fixed structure (212) includes an adjustable damping mechanism.
5. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 3, characterized in that: The elastic beam with a gradual cross-section is arranged on the vibration transmission path.
6. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 2, characterized in that: The intermediate fixed connection structure (212) adopts a bistable spring design.
7. The broadband vibration energy harvesting device based on multi-level vibration energy coupling according to claim 1, characterized in that: The energy collector body (1) comprises a composite energy conversion unit: Low frequency band (5-20Hz): uses electromagnetic power generation components, including NdFeB permanent magnets and 3D printed micro coils; Medium and high frequency band (20-120Hz): piezoelectric composite materials are used.
8. A collection method of a broadband vibration energy collection device based on multi-level vibration energy coupling, characterized in that: include: Step S1: coupling broadband vibration energy to a target frequency band step by step through a multi-stage elastic structure group (21); Step S2: exciting resonance amplification at the intermediate fixed structure (212); Step S3: using the elastic structure (211) with gradient stiffness to achieve cross-band impedance matching; Step S4: Efficiently generate electricity in different frequency bands through a composite energy conversion unit.