An elastic wave-based wireless energy transmission system and method

Abstract

The application belongs to the technical field of elastic wave modulation and regulation, and relates to a wireless energy transmission system and method based on elastic waves. The system comprises: a piezoelectric transmitting transducer for converting an applied electric excitation into an elastic longitudinal wave propagating in the thickness direction; an elastic medium to be penetrated for serving as an intermediate resonant state to propagate the elastic longitudinal wave; a piezoelectric receiving transducer for converting the elastic longitudinal wave into an electric signal and outputting the electric signal to a load; and an elastic coupling layer arranged between the piezoelectric transmitting transducer and the elastic medium to be penetrated and between the piezoelectric receiving transducer and the elastic medium to be penetrated for providing mechanical coupling. Based on the above system, the problem of poor adaptability of conventional elastic wave energy transmission to working conditions is solved.

Description

Technical Field

[0001] This application relates to the field of elastic wave regulation technology, and in particular to a wireless power transmission system and method based on elastic waves. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. It should not be construed as an admission that the description herein is prior art.

[0003] Wireless power transfer technology has attracted much attention because it can eliminate the need for physical wires. In existing technologies, electromagnetic wave-based methods (such as magnetic resonance coupling) can achieve wireless power supply over a certain distance, but their efficiency is heavily dependent on precise circuit tuning, they are extremely sensitive to load changes, and they cannot penetrate metal shielding shells, which fundamentally limits their application in enclosed metal environments.

[0004] Elastic wave-based transmission technology offers the possibility of power transmission through metal. However, current elastic wave systems are mostly designed based on classical linear elasticity theory, and their efficient transmission state can only be achieved at specific load and frequency points. Once the load impedance changes in actual operating conditions, the system will become detuned, leading to a sharp drop in transmission efficiency. Therefore, existing elastic wave wireless power transmission systems generally suffer from poor adaptability to operating conditions and insufficient robustness. Summary of the Invention

[0005] The present invention provides a wireless power transmission system and method based on elastic waves, which at least solves the problems of traditional elastic wave power transmission being sensitive to operating conditions and having poor adaptability.

[0006] According to a first aspect of the present invention, a wireless power transfer system based on elastic waves is provided, comprising: Piezoelectric transmitting transducers are used to convert external electrical excitation into elastic longitudinal waves that propagate along the thickness direction; The elastic medium to be penetrated is used as an intermediate resonant state to propagate the elastic longitudinal wave; A piezoelectric receiving transducer is used to convert the elastic longitudinal wave into an electrical signal and output it to the load; An elastic coupling layer is disposed between the piezoelectric transmitting transducer and the elastic medium to be penetrated, and between the piezoelectric receiving transducer and the elastic medium to be penetrated, for providing mechanical coupling; Wherein: the frequency difference between the first-order longitudinal resonant frequencies of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer is within a preset frequency difference range; the material and thickness of the elastic coupling layer are configured such that the elastic coupling layer does not generate self-resonance at the first-order longitudinal resonant frequency, thereby forming weak mechanical coupling; the internal resistance of the power supply connected to the piezoelectric transmitting transducer and the load impedance of the piezoelectric receiving transducer satisfy an impedance matching relationship, and the ratio of the internal resistance of the power supply to the load impedance is within a preset ratio range.

[0007] According to a second aspect of the present invention, a wireless power transfer method based on elastic waves is provided, comprising: A piezoelectric transmitting transducer, a piezoelectric receiving transducer, and an elastic coupling layer are fixed to the outside of the elastic medium to be penetrated, wherein the elastic coupling layer is located between the transmitting transducer and the elastic medium to be penetrated, and between the receiving transducer and the elastic medium to be penetrated. An alternating voltage signal is applied between the two electrodes of the piezoelectric transmitting transducer, and the excitation frequency is set to match the first-order longitudinal resonant frequency of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer. The alternating voltage signal is converted into an elastic longitudinal wave that propagates along the thickness direction by a piezoelectric transmitting transducer. The elastic longitudinal wave is transmitted to the elastic medium to be penetrated through the elastic coupling layer and propagates to the piezoelectric receiving transducer. The piezoelectric receiving transducer converts the received elastic longitudinal wave into an electrical signal and outputs electrical energy to the connected load.

[0008] Beneficial effects of the embodiments of the present invention: This invention provides a wireless power transmission system based on elastic waves. By ensuring high resonant frequencies among the transmitting transducer, the medium to be penetrated, and the receiving transducer, and by establishing a non-resonant weak coupling layer between them, while simultaneously satisfying specific impedance matching between the power supply and the load, the system operates under equivalent anti-PT symmetry conditions. This system achieves near-theoretical-limit-efficiency power transmission near a preset frequency, and this high efficiency is robust to a wide range of load variations, maintaining stable output without external tuning. Furthermore, based on the elastic wave penetration mechanism, the system effectively overcomes electromagnetic shielding, enabling wireless power supply to devices inside metal structures. In summary, this system solves the key problems of traditional elastic wave power transmission, such as sensitivity to operating conditions and poor adaptability, demonstrating outstanding practicality in complex industrial environments.

[0009] Details of one or more embodiments of the present invention are set forth in the following drawings and description, so that other features, objects and advantages of the invention will be more readily understood. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of a wireless power transmission system based on elastic waves, provided as an embodiment of the present invention.

[0012] Figure 2 A flowchart of a wireless power transmission method based on elastic waves provided for an embodiment of the present invention.

[0013] Figure 3 This is a cloud map showing the distribution of system transmission efficiency as a function of excitation frequency and load impedance, provided for an embodiment of the present invention.

[0014] Figure 4 This is a curve showing the change in system transmission efficiency with load impedance when the excitation frequency is 64kHz, provided as an embodiment of the present invention.

[0015] Figure 5 This is a cloud map showing the distribution of system transmission efficiency when the ratio of power supply internal resistance to load impedance is 2.5, provided for an embodiment of the present invention.

[0016] Figure 6 This is a cloud map showing the distribution of system transmission efficiency when the ratio of power supply internal resistance to load impedance is 0.4, provided for an embodiment of the present invention.

[0017] Figure 7 This is a distribution diagram of the system transmission efficiency as a function of impedance ratio when the load impedance is 40kΩ, provided for an embodiment of the present invention.

[0018] In the diagram: 1. Piezoelectric transmitting transducer; 2. Elastic medium to be penetrated; 3. Piezoelectric receiving transducer; 4. Elastic coupling layer; 5. External power supply; 6. Load. Detailed Implementation

[0019] Embodiments of this embodiment will now be described in more detail with reference to the accompanying drawings. While some embodiments of this embodiment are shown in the drawings, it should be understood that this embodiment can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this embodiment. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this embodiment.

[0020] Wireless power transfer technology has attracted attention due to its lack of wire constraints. Traditional electromagnetic wave and directional / magnetic resonance technologies all suffer from shortcomings in efficiency, risk, or adaptability. Electromagnetic waves cannot penetrate metal, a problem that elastic waves can solve. However, the performance of traditional elastic wave systems depends on preset operating conditions; parameter deviations lead to a sharp drop in efficiency, limiting their applications. In summary, in metal-penetrating scenarios, traditional elastic wave systems are sensitive to operating conditions and have poor adaptability.

[0021] To address the aforementioned problems, embodiments of the present invention provide a wireless power transmission system and a wireless power transmission method based on elastic waves.

[0022] Figure 1 This is a schematic diagram of a wireless power transmission system based on elastic waves, provided as an embodiment of the present invention.

[0023] like Figure 1 As shown, the wireless power transmission system includes a piezoelectric transmitting transducer 1, an elastic medium to be penetrated 2, a piezoelectric receiving transducer 3, and an elastic coupling layer 4.

[0024] The piezoelectric transmitting transducer 1 is used to convert external electrical excitation into an elastic longitudinal wave that propagates along the thickness direction.

[0025] In this embodiment, the piezoelectric transducer 1 serves as the core of the system's energy input and electromechanical conversion. Its function is to convert the electrical energy provided by the external power supply 5 into mechanical vibrations propagating in a specific direction, i.e., elastic longitudinal waves in this embodiment. Its working mechanism is based on the inverse piezoelectric effect: when an alternating voltage is applied between the two electrodes of the piezoelectric material, periodic polarization changes occur within the material, causing the crystal structure to stretch and deform along a specific direction (thickness direction in this embodiment), thereby exciting and radiating elastic longitudinal waves. To achieve efficient excitation, the transducer can be configured to operate in a thickness vibration mode, and its geometry (e.g., thickness dimension) determines its first-order longitudinal resonant frequency. Depending on the specific implementation requirements, this frequency is adjusted to ensure that the transducer is in a resonant state near the operating frequency point, where the electromechanical coupling coefficient is at its maximum, and the electrical energy... The mechanical energy conversion efficiency is the highest. In system integration, the transducer is mechanically connected to the medium to be penetrated through the elastic coupling layer 4, and its vibration energy is transmitted into the interior of the medium through the coupling layer.

[0026] The elastic medium 2 to be penetrated is used as an intermediate resonant state to propagate elastic longitudinal waves.

[0027] In this embodiment, the elastic medium 2 to be penetrated can serve as a physical channel for the propagation of elastic waves, or as an intermediate resonant state of the entire resonant system. Specifically, from the perspective of the transmission channel, the medium can be a metallic material (such as steel, aluminum, etc.) due to its good mechanical strength and elastic waveguide characteristics; from the perspective of the resonant system, the medium is configured to have a longitudinal resonant frequency that matches the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3. In practical applications, elastic media 2 with different geometric dimensions and materials can be selected to ensure that their first-order longitudinal resonant frequency falls within the target operating frequency band. When the resonant frequencies of the three resonant units, namely the piezoelectric transmitting transducer 1, the elastic medium 2 to be penetrated, and the piezoelectric receiving transducer 3, are highly consistent, the entire system will form a synergistic resonance at a specific frequency point, and energy can circulate efficiently among the three rather than be dissipated or reflected by the medium.

[0028] The piezoelectric receiving transducer 3 is used to convert the elastic longitudinal wave into an electrical signal and output it to the load 6.

[0029] In this embodiment, the piezoelectric receiving transducer 3 is functionally symmetrical and complementary to the piezoelectric transmitting transducer 1. Its function is to convert the mechanical vibration energy propagating to the receiving position back into electrical energy through the positive piezoelectric effect. When the elastic longitudinal wave propagates to the piezoelectric receiving transducer 3, periodic stress is generated inside it, causing induced charges to be generated at both ends of the electrodes, forming an alternating voltage output to the load circuit 6. To achieve high sensitivity and high efficiency, the receiving transducer is also designed to operate near its first-order longitudinal resonant frequency. Its structural parameters can be consistent with or symmetrical with the transmitting transducer to ensure that the system has symmetrical vibration modes and impedance characteristics at the resonant frequency, which is beneficial to maximizing energy transfer and stability.

[0030] The elastic coupling layer 4 is disposed between the piezoelectric transmitting transducer 1 and the elastic medium 2 to be penetrated, and between the piezoelectric receiving transducer 3 and the elastic medium 2 to be penetrated, to provide mechanical coupling.

[0031] In this embodiment, the elastic coupling layer 4 serves as an energy coupling and transfer element in the system, rather than a resonant element. Its material can be a low-density, low-wave velocity elastic material (such as epoxy resin or specific polymers) with appropriate flexibility.

[0032] In practical applications, the thickness and material parameters of the elastic coupling layer 4 can be controlled to make its resonant frequency significantly higher than the system's operating frequency. This ensures that within the operating frequency band, the coupling layer itself does not resonate significantly and only acts as an "elastic bridge" for transmitting vibrations. This weak coupling design allows energy to be mainly stored in three resonant states and exchanged through resonant coupling between them. This is beneficial for forming system dynamics with specific non-Hermitian characteristics and achieving efficient transmission that is insensitive to the load 6.

[0033] In this embodiment, the first-order longitudinal resonant frequencies of the three resonant units in the system—the piezoelectric transmitting transducer 1, the elastic medium to be penetrated 2, and the piezoelectric receiving transducer 3—must be kept very close, and their frequency difference can be controlled within a narrow preset frequency difference range. In practical applications, when the resonant frequencies of the three are consistent, the system will exhibit a special coupled intrinsic mode in the equivalent lumped parameter model or distributed parameter model. The resonant frequency of this intrinsic mode is always consistent with the resonant frequency of the single resonant mode and is independent of other system parameters.

[0034] In this embodiment, the material and thickness of the elastic coupling layer 4 are configured such that the elastic coupling layer 4 does not resonate at the first-order longitudinal resonant frequency, thus forming a weak mechanical coupling. In practical applications, the "non-resonant" characteristic of the elastic coupling layer 4 is actively achieved through its material selection and geometric design. Specifically, the ratio of its thickness to the material's sound velocity is designed so that the first-order longitudinal resonant frequency of the coupling layer is much higher than the system's operating frequency. Thus, at the operating frequency, the coupling layer behaves as a purely elastic connecting element, and its dynamic behavior can be approximated by static stiffness without introducing additional resonance peaks or phase abrupt changes. Based on the above configuration, it can be ensured that the coupling effect in the system is smooth and controllable, without disrupting the cooperative relationship between the three main resonant states.

[0035] In this embodiment, the internal resistance of the power supply connected to the piezoelectric transmitting transducer 1 and the impedance of the load 6 of the piezoelectric receiving transducer 3 satisfy an impedance matching relationship, and the ratio of the internal resistance of the power supply to the impedance of the load 6 is within a preset range. Specifically, the ratio between the internal resistance of the power supply and the impedance of the load 6 can be within a specific range. This ratio range is not a traditional conjugate matching, but rather stems from the gain-loss balance condition required in non-Hermitian systems to achieve specific eigenstates (such as real eigenvalues ​​under anti-PT symmetry). Under this matching relationship, the system can achieve near-perfect energy transfer efficiency at a specific frequency, and this efficiency is insensitive to changes in the impedance of the load 6 over a wide range, thus giving the system significant robustness. In practical applications, this preset ratio range includes 0.4 to 2.5.

[0036] In an optional embodiment, both the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 are piezoelectric ceramic pillars, and the materials of the piezoelectric ceramic pillars include: PZT-5H and PZT-5A.

[0037] In this embodiment, both the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 are piezoelectric ceramic cylinders. The cylindrical structure (circular cross-section) has significant advantages in axisymmetric elastic wave excitation and reception: its regular geometry facilitates accurate theoretical modeling (such as a one-dimensional longitudinal vibration model) and frequency calculation; during vibration in the thickness direction, the sides of the cylinder are free boundaries, which helps to concentrate the vibration energy in the axial direction (thickness direction), reducing radiation loss to the sides, thereby improving the directness of energy conversion and transmission. In addition, the cylindrical structure is easy to obtain consistent dimensions through precision machining, and it is also easy to achieve end-to-end contact with the coupling layer and the medium to be penetrated, which are also cylindrical, ensuring the flatness of the contact surface and the uniformity of coupling.

[0038] In addition, piezoelectric ceramic pillars can be made of materials such as PZT-5H and PZT-5A. Taking PZT-5H and PZT-5A as examples, these two materials have high electromechanical coupling coefficients and high dielectric constants, stable and reliable performance parameters, and are easy to process into the required pillar shapes. In practical applications, depending on the different emphasis requirements of conversion efficiency, sensitivity, and resonance peak sharpness in the system design, these two or other PZT materials with similar properties can be selected.

[0039] In one optional embodiment, the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 have the same diameter, and the diameter-to-thickness ratio of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 is less than 0.5.

[0040] In this embodiment, the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 have the same diameter, that is, the piezoelectric ceramic pillars of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 have the same cross-sectional diameter.

[0041] In practical applications, the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 have the same diameter, ensuring geometric symmetry in the mechanical vibration characteristics and acoustic impedance distribution of the two piezoelectric transducers in the system. When the transducers have the same diameter, the planar wavefront areas generated when they vibrate in the thickness direction are equal, which is beneficial for achieving wavefield matching when elastic waves enter and exit the medium to be penetrated through the coupling layer, reducing energy loss caused by beam spread, reflection, or mode conversion due to abrupt changes in cross-section. This symmetrical design also makes it easier to achieve symmetry in the equivalent circuit parameters between the transmitting and receiving ends.

[0042] In addition, the diameter-to-thickness ratio (the ratio of diameter to thickness) of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 is less than 0.5, which can ensure that their vibration mode is mainly longitudinal vibration in the thickness direction, effectively suppressing the excitation of radial vibration or other stray modes.

[0043] In an optional embodiment, the elastic medium 2 to be penetrated is a metal cylinder. The diameter of the elastic medium 2 to be penetrated is the same as that of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3, and the thickness is configured such that the frequency difference between the first-order longitudinal resonant frequency of the elastic medium 2 to be penetrated and the first-order longitudinal wave resonant frequency of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3 is within a preset frequency difference range.

[0044] In an optional embodiment, the first-order longitudinal mechanical resonant frequency of the piezoelectric transmitting transducer 1 It is calculated using the following formula (1): (1) in, Let be the elastic compliance constant. For material density, The thickness is the material thickness.

[0045] In this embodiment, the elastic medium 2 to be penetrated is the physical channel for elastic wave propagation in this system, and also one of the core units constituting the three-harmonic coupling. The medium to be penetrated is provided with a metal cylinder because metallic materials (such as steel, aluminum, titanium alloys, etc.) can effectively bear and propagate elastic longitudinal waves, and are widely used in engineering practice for the shells or structural components of various equipment, such as aerospace vehicle skins, underwater vehicle pressure hulls, and industrial sealed cabins. The cylindrical geometry has axisymmetry, which is beneficial for exciting pure longitudinal vibration modes, avoiding interference from bending or torsional modes, thereby simplifying the dynamic behavior of the system and facilitating precise frequency matching and control. One end of the metal cylinder is connected to the piezoelectric transmitting transducer 1 through an elastic coupling layer 4, and the other end is connected to the piezoelectric receiving transducer 3 through another elastic coupling layer 4, forming a series structure of transmitter-medium-receiver.

[0046] The diameter of the elastic medium 2 to be penetrated is set to be the same as that of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3. This ensures that when the transducers and the elastic medium 2 are connected through the elastic coupling layer 4, the vibration energy can be uniformly transmitted along the cross-section, thereby maintaining a single propagation mode of the elastic longitudinal wave. In actual manufacturing and assembly, the consistent diameter also facilitates processing, positioning, and bonding, ensuring the axisymmetry and mechanical stability of the system structure.

[0047] In this embodiment, the thickness of the elastic medium 2 to be penetrated directly determines its first-order longitudinal resonant frequency. For a cylindrical elastic body, its first-order longitudinal resonant frequency is... It is calculated using the following formula (2): (2) in, The thickness of the elastic medium 2 to be penetrated. For Young's modulus, This represents the material density.

[0048] To achieve coordinated operation of the three resonant states, the first-order longitudinal resonant frequency of the elastic medium 2 to be penetrated needs to be set to be basically consistent with the first-order longitudinal wave resonant frequencies of the piezoelectric transmitting transducer 1 and the piezoelectric receiving transducer 3. The frequency difference between the three can be controlled within a preset range (e.g., 0~2kHz). Depending on the specific application, by selecting an appropriate metal material and controlling its thickness, the resonant frequency of the elastic medium 2 to be penetrated can be made to fall into the target frequency band, thereby meeting the frequency matching conditions required for the system to achieve efficient and robust transmission.

[0049] In an alternative embodiment, the material of the elastic coupling layer 4 includes epoxy resin, and the thickness is configured such that the first-order longitudinal resonant frequency of the elastic coupling layer 4 is much greater than that of the piezoelectric ceramic pillar and the metal cylinder, so as to ensure that the elastic coupling layer 4 provides only weak mechanical coupling.

[0050] In this embodiment, epoxy resin is used as the coupling layer material from a material selection perspective. Epoxy resin is a polymer material with an acoustic impedance between that of piezoelectric ceramics and metal materials, which can achieve impedance matching to a certain extent. More importantly, the elastic wave velocity of epoxy resin is significantly lower than that of piezoelectric ceramics and metal materials. This characteristic makes the resonant frequency of the epoxy resin structure much higher than that of the piezoelectric ceramic cylinder and the metal cylinder under the same geometric dimensions.

[0051] At the operating frequency, the elastic coupling layer 4 itself does not resonate; its dynamic behavior is that of a purely elastic connecting element rather than an additional resonant unit. In other words, the elastic coupling layer 4 only serves to transmit mechanical vibrations and does not participate in the system's resonant energy storage. This design ensures that the energy in the system is mainly stored in the three main resonant units (the transmitting transducer, the medium to be penetrated, and the receiving transducer), and is exchanged between them through the weak mechanical coupling provided by the coupling layer, thus forming a three-resonant coupling structure that conforms to the theoretical expectations of non-Hermitian systems.

[0052] Based on the above embodiments, the load 6, which can achieve efficient energy transfer, has an impedance operating range of 20 kΩ to 80 kΩ.

[0053] Figure 2 This is a flowchart illustrating a wireless power transfer method based on elastic waves, provided as an embodiment of the present invention. Figure 2 As shown, the method includes the following steps: Step S201: Fix the piezoelectric transmitting transducer, the piezoelectric receiving transducer and the elastic coupling layer to the outside of the elastic medium to be penetrated, wherein the elastic coupling layer is located between the transmitting transducer and the elastic medium to be penetrated and between the receiving transducer and the elastic medium to be penetrated.

[0054] Step S202: An alternating voltage signal is applied between the two electrodes of the piezoelectric transmitting transducer, and the excitation frequency is set to match the first-order longitudinal resonant frequency of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer.

[0055] In step S203, the alternating voltage signal is converted into an elastic longitudinal wave propagating along the thickness direction by a piezoelectric transmitting transducer. The elastic longitudinal wave is transmitted to the elastic medium to be penetrated through the elastic coupling layer and propagates to the piezoelectric receiving transducer.

[0056] Step S204: The received elastic longitudinal wave is converted into an electrical signal by a piezoelectric receiving transducer and the electrical energy is output to the connected load.

[0057] First, a piezoelectric transmitting transducer, a piezoelectric receiving transducer, and an elastic coupling layer are fixed to the outside of the elastic medium to be penetrated, wherein the elastic coupling layer is located between the transmitting transducer and the elastic medium to be penetrated, and between the receiving transducer and the elastic medium to be penetrated.

[0058] In this embodiment, the transmitting transducer and the receiving transducer are mechanically connected to the elastic medium to be penetrated via an elastic coupling layer, forming a stacked structure of "piezoelectric transmitting transducer - elastic coupling layer - elastic medium to be penetrated - elastic coupling layer - piezoelectric receiving transducer". The elastic coupling layer is located between the piezoelectric transmitting transducer, the piezoelectric receiving transducer, and the elastic medium to be penetrated, acting as a bridge for mechanical impedance matching and elastic wave transmission. This assembly method ensures that the elastic wave excited by the transmitting transducer can be efficiently transmitted into the medium and smoothly reach the receiving transducer after propagation through the medium. The components are usually fixed by adhesive bonding (such as AB glue) to ensure good mechanical contact and acoustic matching at the interface, reducing energy reflection and loss at the interface.

[0059] Then, an alternating voltage signal is applied between the two electrodes of the piezoelectric transmitting transducer, and the excitation frequency is set to match the first-order longitudinal resonant frequency of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer.

[0060] In this embodiment, an alternating voltage is applied across the transmitting transducer, which is then converted into mechanical vibration using the inverse piezoelectric effect. The selection of the excitation frequency is crucial: it must be set near the first-order longitudinal resonant frequency of the three resonant units (transmitting transducer, the medium to be penetrated, and receiving transducer), so that all three are simultaneously in or close to a resonant state. This frequency matching design enables the system to achieve synergistic resonance at a specific frequency point, allowing energy to circulate efficiently between the three resonant states, a prerequisite for achieving high-efficiency energy transfer.

[0061] The alternating voltage signal is converted into an elastic longitudinal wave that propagates along the thickness direction by a piezoelectric transmitting transducer. The elastic longitudinal wave is transmitted to the elastic medium to be penetrated through the elastic coupling layer and then propagates to the piezoelectric receiving transducer.

[0062] In this embodiment, the piezoelectric transmitting transducer undergoes periodic deformation under alternating voltage excitation, generating an elastic longitudinal wave that propagates along its thickness. This elastic wave first enters the elastic medium to be penetrated through the transmitting coupling layer, then propagates longitudinally within the medium as a particle vibration, finally passing through the medium to reach the receiving coupling layer and being transmitted to the receiving transducer. This process enables wireless energy transmission in a solid medium without relying on electromagnetic waves or physical wires, making it particularly suitable for enclosed scenarios with metal barriers.

[0063] Step S204: The received elastic longitudinal wave is converted into an electrical signal by a piezoelectric receiving transducer and the electrical energy is output to the connected load.

[0064] In this embodiment, the elastic longitudinal wave propagating to the receiving position generates periodic stress inside the piezoelectric receiving transducer. Based on the positive piezoelectric effect, induced charges are generated between the electrodes at both ends of the transducer, forming an alternating voltage output. This electrical signal can directly power the load (such as electronic devices or energy storage units) connected to the receiving end. Through this electromechanical conversion process, the system completes a full wireless transmission link from the transmitting end to the receiving end, realizing wireless power supply to devices inside the enclosed metal structure.

[0065] In one optional embodiment, the frequency difference between the excitation frequency and the first-order longitudinal resonant frequency corresponding to the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer is in the range of 0 to 2 kHz, and the ratio between the internal resistance of the power supply connected to the piezoelectric transmitting transducer and the load impedance connected to the piezoelectric receiving transducer is in the range of 0.4 to 2.5.

[0066] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to specific examples. These examples aim to further illustrate the implementation and beneficial effects of the present invention through a set of specific materials, dimensions, and operating parameters, but should not be construed as limiting the scope of protection of the present invention.

[0067] This embodiment provides a wireless power transmission system based on elastic waves, the structure of which is as follows: Figure 1 As shown, the specific implementation is as follows: Both the piezoelectric transmitting transducer and the piezoelectric receiving transducer are made of PZT-5H piezoelectric ceramic material, machined into a cylindrical shape with a diameter of 6 mm and a thickness of 20 mm. Silver electrodes are plated on both ends, and the electrodes are connected to an external power supply and a load respectively via leads.

[0068] The elastic medium to be penetrated: a cylinder made of 45# steel (or 304 stainless steel), with a diameter of 6 mm and a thickness of 39.8 mm. This medium simulates the metal shell wall in actual applications.

[0069] Elastic coupling layer: Made of epoxy resin, processed into a cylindrical sheet with a diameter of 6 mm and a thickness of 6 mm. Two coupling layers are required, one placed between the transmitting transducer and the elastic medium to be penetrated, and the other between the receiving transducer and the elastic medium to be penetrated.

[0070] Based on the above embodiments, calculations show that the first-order longitudinal wave resonant frequency of the piezoelectric transmitting transducer and the piezoelectric receiving transducer is 63.4 kHz, and the first-order longitudinal wave resonant frequency of the steel dielectric to be penetrated is also 63.4 kHz. In this embodiment, the frequency difference between the two is 0, satisfying the preset frequency difference range (0~2 kHz). Furthermore, the first-order longitudinal wave resonant frequency of the elastic coupling layer is approximately 208 kHz, far higher than the operating frequency of 63.4 kHz. Therefore, the coupling layer does not self-resonate at the operating frequency, providing only weak mechanical coupling.

[0071] After cleaning the end faces of each component, apply AB adhesive evenly and bond them in the following order: transmitting transducer - elastic coupling layer - elastic medium to be penetrated - elastic coupling layer - receiving transducer. Ensure coaxiality during bonding and allow to cure for 24 hours.

[0072] The two electrodes of the piezoelectric transmitting transducer are connected to an AC voltage source with an internal resistance of 50 kΩ. The two electrodes of the piezoelectric receiving transducer are connected to a variable load resistor, the value of which can be adjusted within the range of 20 kΩ to 80 kΩ.

[0073] Figure 3 This is a cloud map showing the distribution of system transmission efficiency as a function of excitation frequency and load impedance, provided for an embodiment of the present invention.

[0074] like Figure 3 As shown, within a wide range of load impedance Z0 from 30 kΩ to 80 kΩ, the excitation frequency corresponding to achieving 100% complete energy transfer (marked by black dots in the figure) is basically stable around 64 kHz.

[0075] Figure 4 This is a curve showing the change in system transmission efficiency with load impedance when the excitation frequency is 64kHz, provided as an embodiment of the present invention.

[0076] like Figure 4 As shown, when the load impedance Z0 is greater than 20 kΩ, the system's energy transfer efficiency can always be maintained above 90%.

[0077] This result confirms that the system constructed in this embodiment has achieved its design goals: while penetrating the metallic medium, it has extremely strong robustness to a wide range of load impedance changes and can maintain efficient energy transmission without retuning system parameters.

[0078] Figure 5This is a cloud map showing the distribution of system transmission efficiency when the ratio of power supply internal resistance to load impedance is 2.5, provided for an embodiment of the present invention.

[0079] like Figure 5 As shown in the figure, a color gradient is used to represent the transmission efficiency, with blue areas representing low efficiency and red areas representing high efficiency. A clear red high-efficiency transmission band can be observed across the entire load impedance range (20~80kΩ). This high-efficiency region is concentrated at a specific frequency around 64kHz, indicating that when the excitation frequency matches the first-order longitudinal resonant frequency of the system's three resonant units (piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer), the system can achieve near 100% energy transmission efficiency over a wide range of load variations.

[0080] Figure 6 This is a cloud map showing the distribution of system transmission efficiency when the ratio of power supply internal resistance to load impedance is 0.4, provided for an embodiment of the present invention.

[0081] like Figure 6 As shown in the figure, a color gradient is used to represent transmission efficiency, with blue areas indicating low efficiency and red areas indicating high efficiency. It can be observed from the figure that there is a high-efficiency region at a specific frequency on the left, and a distinct high-efficiency band extends laterally, covering a wide range of load impedances. This indicates that when the system operates near the resonant frequency, even if the ratio of the power supply internal resistance to the load impedance decreases to 0.4, the system can still achieve near-efficient energy transfer with a high efficiency of close to 1 over a large range of load variations.

[0082] Figure 7 This is a distribution diagram of the system transmission efficiency as a function of impedance ratio when the load impedance is 40kΩ, provided for an embodiment of the present invention.

[0083] like Figure 7 As shown, when the ratio of the power supply internal resistance to the load impedance is in the range of 0.4 to 2.5, the system's energy transmission efficiency can be stably maintained at over 90%, which fully verifies that the elastic wave-based wireless energy transmission system has excellent impedance adaptability and transmission robustness.

[0084] The above embodiments are merely preferred examples of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0085] It should be noted that the term "comprising" and its variations used in the embodiments of the present invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present invention are illustrative and not restrictive. Those skilled in the art should understand that, unless explicitly indicated otherwise in the context, they should be understood as "one or more".

[0086] The steps described in the method embodiments provided by this invention can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of this invention is not limited in this respect.

[0087] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0088] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A wireless power transmission system based on elastic waves, characterized in that, include: Piezoelectric transmitting transducers are used to convert external electrical excitation into elastic longitudinal waves that propagate along the thickness direction; The elastic medium to be penetrated is used as an intermediate resonant state to propagate the elastic longitudinal wave; A piezoelectric receiving transducer is used to convert the elastic longitudinal wave into an electrical signal and output it to the load; An elastic coupling layer is disposed between the piezoelectric transmitting transducer and the elastic medium to be penetrated, and between the piezoelectric receiving transducer and the elastic medium to be penetrated, for providing mechanical coupling; Wherein: the frequency difference between the first-order longitudinal resonant frequencies of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer is within a preset frequency difference range; The material and thickness of the elastic coupling layer are configured such that the elastic coupling layer does not resonate at the first-order longitudinal resonant frequency, thereby forming a weak mechanical coupling; the internal resistance of the power supply connected to the piezoelectric transmitting transducer and the load impedance of the piezoelectric receiving transducer satisfy an impedance matching relationship, and the ratio of the internal resistance of the power supply to the load impedance is within a preset ratio range.

2. The wireless power transmission system according to claim 1, characterized in that, Both the piezoelectric transmitting transducer and the piezoelectric receiving transducer are piezoelectric ceramic pillars, and the materials of the piezoelectric ceramic pillars include: PZT-5H and PZT-5A.

3. The wireless power transmission system according to claim 2, characterized in that, The piezoelectric transmitting transducer and the piezoelectric receiving transducer have the same diameter, and the diameter-to-thickness ratio of the piezoelectric transmitting transducer and the piezoelectric receiving transducer is less than 0.

5.

4. The wireless power transmission system according to claim 1, characterized in that, The elastic medium to be penetrated is a metal cylinder; The diameter of the elastic medium to be penetrated is the same as that of the piezoelectric transmitting transducer and the piezoelectric receiving transducer, and the thickness is configured such that the frequency difference between the first-order longitudinal resonant frequency of the elastic medium to be penetrated and the first-order longitudinal wave resonant frequency of each of the piezoelectric transmitting transducer and the piezoelectric receiving transducer is within the range of the preset frequency difference value.

5. The wireless power transmission system according to claim 1, characterized in that, The material of the elastic coupling layer includes epoxy resin, and the thickness is configured such that the first-order longitudinal resonant frequency of the elastic coupling layer is much greater than that of the piezoelectric ceramic pillar and the metal cylinder, so as to ensure that the elastic coupling layer provides only weak mechanical coupling.

6. The wireless power transmission system according to claim 1, characterized in that, The preset frequency difference range includes 0~2kHz; the preset ratio range includes 0.4~2.

5.

7. The wireless power transfer system according to any one of claims 1 to 6, characterized in that, The operating range of the load impedance is 20 kΩ to 80 kΩ.

8. A wireless power transfer method based on elastic waves, characterized in that, include: A piezoelectric transmitting transducer, a piezoelectric receiving transducer, and an elastic coupling layer are fixed to the outside of the elastic medium to be penetrated, wherein the elastic coupling layer is located between the transmitting transducer and the elastic medium to be penetrated, and between the receiving transducer and the elastic medium to be penetrated. An alternating voltage signal is applied between the two electrodes of the piezoelectric transmitting transducer, and the excitation frequency is set to match the first-order longitudinal resonant frequency of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer. The alternating voltage signal is converted into an elastic longitudinal wave that propagates along the thickness direction by a piezoelectric transmitting transducer. The elastic longitudinal wave is transmitted to the elastic medium to be penetrated through the elastic coupling layer and propagates to the piezoelectric receiving transducer. The piezoelectric receiving transducer converts the received elastic longitudinal wave into an electrical signal and outputs electrical energy to the connected load.

9. The method according to claim 8, characterized in that, The frequency difference between the excitation frequency and the first-order longitudinal resonant frequency of the piezoelectric transmitting transducer, the elastic medium to be penetrated, and the piezoelectric receiving transducer is in the range of 0 to 2 kHz, and the ratio between the internal resistance of the power supply connected to the piezoelectric transmitting transducer and the load impedance connected to the piezoelectric receiving transducer is in the range of 0.4 to 2.5.

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