Multi-degree-of-freedom compound wave energy converter

Abstract

The present application relates to a kind of multi-degree-of-freedom compound wave energy converter, belong to wave power generation technical field.The installation frame and power generation component, power generation component includes electromagnetic generator unit, nanometer friction power generation unit and piezoelectric power generation unit;Electromagnetic generator unit includes gravity pendulum and electromagnetic generator;Gravity pendulum is installed in installation frame around wave energy converter gravity center axis rotation, and one end is connected with the rotor of electromagnetic generator;Nanometer friction power generation unit includes several power generation components containing friction material, power generation component is installed in installation frame, and under the action of external force, relative motion occurs between power generation component, to generate electric energy;Piezoelectric power generation unit includes piezoelectric generator and water flow turbine;The rotor shaft of piezoelectric generator is connected with water flow turbine, and its rotor is made of piezoelectric material, and magnet is respectively arranged on rotor and stator.The present application can be fully and efficiently captured on multiple degrees of freedom to wave, energy conversion efficiency is high and the scope of application is wide.

Description

Technical Field

[0001] This invention relates to the field of wave power generation technology, specifically to a multi-degree-of-freedom composite wave energy converter. Background Technology

[0002] The ocean covers more than 70% of the Earth's surface and contains abundant resources for future sustainable development. Long-term, continuous, and multidisciplinary comprehensive observation of the vast ocean is of significant strategic and scientific importance not only for global scientific research, marine resource development, and marine environmental monitoring, but also plays a crucial role in promoting global climate change response and the sustainable use of the ocean. Currently, tens of thousands of ocean observation platforms equipped with various sensors are in operation, aiming to build a global three-dimensional observation network. However, these systems require substantial energy to ensure long-term stable operation and to capture diverse sensor data. Large-capacity batteries and low power consumption alone are insufficient to support the long-term mobile operation of observation platforms, especially when the platforms are far from land, making battery replacement extremely difficult. Therefore, developing ocean energy harvesting technologies to achieve long-term self-sustaining operation of observation systems has become an urgent issue to be addressed.

[0003] Wave energy, as one of the most abundant renewable energy sources in the ocean, boasts advantages such as wide distribution, low acquisition cost, and immunity to diurnal and atmospheric circulation effects, making it an ideal power source for ocean observation systems. However, the characteristics of wave energy, including ultra-low frequency and multiple degrees of freedom, have prevented current technologies from efficiently capturing and utilizing it. In recent years, the rapid development of vibration energy harvesting technology, especially miniaturized direct-drive wave energy harvesters, has attracted considerable attention from researchers. Wave energy conversion devices utilize the kinetic and potential energy of water waves through efficient energy capture mechanisms, converting mechanical energy into electrical energy using electromagnetic, piezoelectric, or triboelectric methods. For example, existing technologies include a gravity pendulum electromagnetic wave energy harvesting system that captures wave energy through a vertical horizontal pendulum structure, and whose output electrical waveform reflects the dynamics of the waves; a piezoelectric wave energy harvester using a cylindrical and conical floating body structure that generates high-frequency vibrations by driving a piezoelectric cantilever beam through magnetic coupling by moving the low-frequency floating body up and down; and a triboelectric nanogenerator with a gyroscope structure for harvesting low-frequency wave energy, in which the internal and external power generation units can move independently in different directions, thus avoiding mutual interference.

[0004] As three commonly used energy harvesting methods, electromagnetic energy harvesting features low voltage and high current, and relatively low internal resistance. However, it requires mechanical mechanisms to convert wave excitation into high-frequency motion to improve electromechanical conversion efficiency. Piezoelectric energy harvesting offers advantages such as simple structure, high energy density, and low cost, but its output power is affected by the excitation frequency. Mechanical modulation is typically needed to match the excitation frequency with the piezoelectric resonant frequency to improve output power. Triboelectric nano-energy harvesting exhibits higher energy conversion efficiency under low-frequency conditions, offering advantages such as high power density, high efficiency, low weight, and low manufacturing cost. However, its output voltage is relatively high, current is relatively low, and internal resistance is relatively high, making energy utilization difficult. Currently, most marine energy harvesting technologies rely on a single energy harvesting method, failing to achieve efficient and sufficient conversion of wave mechanical energy. Furthermore, energy harvesting drive methods, such as offshore wave-crossing, oscillating water column, and oscillating body methods, typically focus only on single-degree-of-freedom energy harvesting vertically to the sea surface, neglecting energy harvesting in multiple directions, resulting in low energy capture efficiency. Therefore, developing a wave energy converter that can harvest wave energy from multiple directions and improve energy conversion efficiency has become one of the key technologies in the field of marine energy harvesting. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-degree-of-freedom composite wave energy converter to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this invention provides a multi-degree-of-freedom composite wave energy converter, which features multiple power generation methods and energy conversion of wave energy across multiple degrees of freedom. By designing a conversion mechanism adaptable to the multi-directional and low-frequency nature of waves, it solves the problems of low wave energy capture efficiency and insufficient energy conversion in existing technologies. The multi-degree-of-freedom composite wave energy converter of this invention aims to achieve comprehensive and efficient capture of wave energy through the design of multiple power generation units and a multi-degree-of-freedom energy harvesting structure, overcoming the limitations of traditional single-degree-of-freedom systems and single-energy conversion methods on the range and efficiency of wave energy acquisition.

[0007] The technical solution of this invention mainly includes two technical design concepts:

[0008] (1) The first technical idea is to design a multi-degree-of-freedom ocean wave energy conversion mechanism. The role of an ocean wave energy converter is to efficiently capture and convert the kinetic and potential energy of waves, thereby transforming the complex mechanical motion of ocean waves into usable regular mechanical motion. Traditional wave energy converters mostly adopt a single-degree-of-freedom design, which cannot fully adapt to the multi-directional motion of waves, resulting in low energy capture efficiency. Therefore, this invention adopts a multi-degree-of-freedom conversion mode, using multiple independent or coupled power generation units to simultaneously respond to the multi-directional motion of waves in multiple degrees of freedom. Specifically, an electromagnetic power generation unit including a gravity pendulum is used to convert the energy in the rotational degree of freedom of the waves; a nano-triboelectric power generation unit is used to convert the energy in the vertical degree of freedom of the waves; and a piezoelectric power generation unit including a water turbine is used to convert the energy in the horizontal degree of freedom of the waves.

[0009] (2) The second technical approach is to realize the conversion of mechanical energy into electrical energy in wave energy converters. Traditional electromagnetic energy harvesting methods have low internal resistance and high current output, which can provide stable energy support for some low-power devices, but the energy conversion efficiency is low for small mechanical displacements or low frequencies. Nano-triboelectric power generation can achieve more efficient energy harvesting under low frequency and small vibration conditions. The charge difference generated by the relative motion between friction materials can be converted into electrical energy. Piezoelectric generators are devices that convert mechanical energy (such as vibration or pressure changes) into electrical energy. Their main advantages are high energy conversion efficiency and long-term stability. Nano-triboelectric power generation and piezoelectric power generation have high energy conversion efficiency under low power, high frequency changes and small amplitude vibrations. They can complement traditional electromagnetic harvesting technologies to improve the capture and conversion efficiency of wave energy, thereby achieving more comprehensive and efficient energy harvesting in the variable marine environment. To improve the efficiency of wave energy harvesting and achieve sensor-driven operation, this invention uses an electromagnetic generator to harvest rotational degree-of-freedom energy converted from a gravity pendulum; a nano-triboelectric generator unit to harvest wave energy from the vertical degree-of-freedom motion of a wave-driven wave energy converter, thereby driving relative motion between power generation components made of frictional materials to generate electrical energy; and a pressure piezoelectric generator unit to harvest horizontal degree-of-freedom energy converted from a water turbine perpendicular to the mounting axis.

[0010] Based on the above technical concept, the present invention provides the following technical solution: a multi-degree-of-freedom composite wave energy converter, comprising a mounting frame and a power generation component, the power generation component comprising an electromagnetic power generation unit, a nano-triboelectric power generation unit, and a piezoelectric power generation unit; the electromagnetic power generation unit comprises a gravity pendulum and an electromagnetic generator; the gravity pendulum is rotatably mounted on the mounting frame around the center of gravity axis of the wave energy converter, and one end of it is connected to the rotor of the electromagnetic generator; the nano-triboelectric power generation unit comprises several power generation components made of frictional materials, the power generation components are mounted on the mounting frame, and under the action of external force, the power generation components undergo relative motion to generate electrical energy; the piezoelectric power generation unit comprises a piezoelectric generator and a water turbine; the rotor shaft of the piezoelectric generator is connected to the water turbine, the rotor of the piezoelectric generator is made of piezoelectric material, and magnets are respectively provided on the rotor and the stator.

[0011] Preferably, the mounting bracket includes a motor support platform, a nano platform, and a mounting shaft; the motor support platform and the nano platform are vertically mounted to the mounting shaft by having through holes in their respective center, and the motor support platform and the nano platform are arranged relatively parallel to each other; the electromagnetic power generation unit is mounted on the upper side of the motor support platform, the nano triboelectric power generation unit is mounted on the upper side of the nano platform, and the piezoelectric power generation unit is mounted on the bottom of the nano platform.

[0012] Preferably, the motor support platform has several mounting seats evenly distributed around the mounting shaft in the circumferential direction, and each mounting seat is equipped with an electromagnetic generator; the gravity pendulum is rotatably mounted on the mounting shaft through bearings, and the gravity pendulum is connected to the rotor of the electromagnetic generator through connecting gears.

[0013] Preferably, the gravity pendulum includes an integrally formed mounting plate and a gravity block; the mounting plate is rotatably mounted on the mounting shaft via bearings, and the plate body extends at least to the outer side of the mounting base; the gravity block is mounted on the outer plate body of the mounting plate, and a rolling element is installed between the bottom of the gravity block and the motor support platform; an internal gear ring is provided on the inner side of the mounting plate, and the rotor of the electromagnetic generator is provided with a connecting gear, the connecting gear meshing with the internal gear ring gear, and the gear transmission ratio between the internal gear ring and the connecting gear is 20:1.

[0014] Preferably, the mounting shaft includes a first mounting shaft, a sliding sleeve, and a second mounting shaft; the first mounting shaft has a hollow structure with a bottom opening, and the sliding sleeve is installed on the bottom opening side; the second mounting shaft is slidably mounted on the bottom opening of the first mounting shaft through the sliding sleeve; the motor support platform is mounted on the shaft body on the opening side of the first mounting shaft, and the nano platform is mounted on the shaft body on the side of the second mounting shaft away from the first mounting shaft.

[0015] Preferably, the motor support platform and the nano platform are provided with several sets of corresponding mounting grooves on their opposite surfaces, and the mounting grooves are evenly distributed along the circumference of their respective platform through holes; an elastic element is installed between each set of mounting grooves.

[0016] Preferably, the plurality of power generation components include a first power generation component, a second power generation component, a third power generation component, and a fourth power generation component; the first power generation component is mounted on the surface of the motor support platform facing the nanoplatform, and from top to bottom includes a first insulating layer, a first metal layer, and a first nano friction layer; the second power generation component is mounted on the surface of the nanoplatform facing the motor support platform, and from top to bottom includes a second metal layer and a second insulating layer; the third power generation component is mounted on the outer side of the second mounting shaft, and includes a third metal layer; the fourth power generation component is mounted on the inner ring of the sliding sleeve, and includes a second nano friction layer.

[0017] Preferably, the first metal layer, the second metal layer, and the third metal layer are all copper layers; the first nano-friction layer and the second nano-friction layer are both polytetrafluoroethylene layers.

[0018] Preferably, the piezoelectric generator is fixedly installed on the bottom surface of the nanoplatform. At least three sets of first magnets are evenly distributed along the circumference of the inner side of the stator. The rotor shaft has the same number of rotors as the first magnets extending outward along the vertical axis. Several rotors are evenly distributed along the circumference of the rotor shaft, and the rotors are made of piezoelectric sheets. A second magnet is provided at the end of the rotor facing the stator. Each set of first magnets and second magnets includes two magnets with different magnetic properties. The two magnets of the first magnet are attached together, and the two magnets of the second magnet are respectively installed on both sides of the end of the piezoelectric sheet.

[0019] Preferably, the water turbine includes a mounting base and several turbine blades; the mounting base is fixedly mounted to the rotor shaft of the piezoelectric generator through the center of the base body, and several mounting rods with their axes perpendicular to the mounting base are evenly distributed along the circumference of the center of the base body on the mounting base, and several turbine blades are mounted on the mounting rods one by one. Beneficial effects

[0020] The multi-degree-of-freedom composite wave energy converter of the present invention sets up multiple power generation units, including an electromagnetic power generation unit, a nano-triboelectric power generation unit and a piezoelectric power generation unit, to achieve simultaneous response to the multi-directional motion of waves in multiple degrees of freedom, so as to convert the mechanical energy of the waves into electrical energy, thereby enabling comprehensive and efficient capture of wave energy and overcoming the limitations of traditional single-degree-of-freedom systems and single-energy conversion methods on the range and efficiency of wave energy acquisition.

[0021] Based on the foregoing, the electromagnetic power generation unit of the present invention includes a gravity pendulum and an electromagnetic generator. The gravity pendulum includes an integrally formed mounting plate and a gravity block. The mounting plate is rotatably mounted on the motor support platform of the mounting frame via bearings, while the gravity block is mounted on the outside of the mounting plate. This allows the gravity block of the gravity pendulum to rotate around the mounting shaft under the influence of gravity when the center of gravity of the multi-degree-of-freedom composite wave energy converter of the present invention is deflected by waves. Simultaneously, an internal gear ring with teeth is provided on the mounting plate, and a mounting seat is provided on the motor support platform for mounting the electromagnetic generator. The rotor shaft of the electromagnetic generator meshes with the internal gear ring of the mounting plate via a connecting gear. This allows the gravity pendulum to drive the rotor of the electromagnetic generator to rotate and generate electricity during rotation, thereby converting the energy of waves in the rotational degree of freedom into power generation. A similar technical approach involves setting a nanoplatform parallel to the motor support platform on the mounting shaft of the mounting frame, and placing an elastic element between the two platforms. The mounting shaft between the two platforms is designed as a telescopic structure. This allows the multi-degree-of-freedom composite wave energy converter of this invention to achieve relative motion between the motor support platform and the nanoplatform due to inertia and wave buoyancy when the wave drives its vertical motion. This motion drives a power generation component made of frictional material to generate electricity. Similarly, a piezoelectric power generation unit, including a piezoelectric generator and a water turbine, is used. The wave drives the water turbine to rotate along the horizontal degree of freedom, which in turn drives a rotor made of piezoelectric material to generate electricity. This multi-degree-of-freedom composite wave converter of the present invention can transform the complex mechanical motion of waves into usable, regular mechanical motion in multiple degrees of freedom, thereby improving energy capture efficiency.

[0022] Building upon the foregoing, to improve the energy conversion efficiency of each power generation unit, the electromagnetic power generation unit of this invention uses a plurality of mounting bases to install a plurality of electromagnetic generators, with the electromagnetic generators evenly distributed at intervals along the circumference of the motor support platform. Furthermore, the transmission ratio between the gear teeth of the internal gear ring of the mounting plate and the connecting gear of the electromagnetic generator rotor is set to 20:1. This allows the rotation of the gravity pendulum to drive the electromagnetic generator to generate electricity when the wave-driven center of gravity of the wave converter of this invention deflects, enabling the low-frequency motion of the wave to drive the small mechanical displacement of the gravity pendulum to high-frequency motion, thereby improving power generation efficiency and energy conversion efficiency. The nano-triboelectric power generation unit of this invention can achieve more efficient energy harvesting under low-frequency, small-vibration conditions of waves. The charge difference generated by the relative motion between the power generation components can be converted into electrical energy. The piezoelectric power generation unit converts the deformation of the piezoelectric sheet into electrical energy, with its main advantages being high-efficiency energy conversion and long-term stability. In addition, the nano-triboelectric power generation unit and piezoelectric power generation unit of the present invention have high energy conversion efficiency under low power, high frequency variation and small amplitude vibration, which can complement the energy harvesting technology of electromagnetic power generation unit, improve the capture and conversion efficiency of wave energy, and thus achieve more comprehensive and efficient energy harvesting in the variable marine environment.

[0023] Based on the foregoing, the nano-triboelectric power generation unit of the present invention comprises a first power generation component, a second power generation component, a third power generation component, and a fourth power generation component. The first power generation component is mounted on the surface of the motor support platform facing the nano-platform, and from top to bottom includes a first insulating layer, a first metal layer, and a first nano-friction layer. The second power generation component is mounted on the surface of the nano-platform facing the motor support platform, and from top to bottom includes a second metal layer and a second insulating layer. The third power generation component is mounted on the outer side of the second mounting shaft and includes a third metal layer. The fourth power generation component is mounted on the inner ring of the sliding sleeve and includes a second nano-friction layer. This allows the motor support platform to move towards the nano-platform in the vertical degree of freedom due to inertia under wave drive, thereby driving the first and second power generation components to generate electricity through contact. Simultaneously, during the relative movement of the two platforms, the first mounting shaft moves towards the second mounting shaft, thereby driving the third and fourth power generation components to generate electricity through sliding friction. This results in a high energy harvesting rate and improved energy utilization. The first power generation component includes a first insulating layer for electrical isolation, a first metal layer (copper layer) to improve conductivity and effectively transmit electrical energy, and a first nano-friction layer (polytetrafluoroethylene layer) for energy conversion. The second power generation component has a second metal layer (copper layer) and a second insulating layer, which are used to generate current through contact and separation with the polytetrafluoroethylene layer, while also providing good conductivity.

[0024] Building upon the foregoing, the piezoelectric power generation unit of this invention uses a rotor made of piezoelectric sheets for energy conversion. Each piezoelectric sheet has magnets with opposite magnetic properties mounted on both sides of its distal end. The stator has a number of first magnets spaced circumferentially, the same number as the piezoelectric sheets. Each set of first magnets includes two magnets bonded together with opposite magnetic properties. The rotor shaft of the piezoelectric generator is equipped with a water turbine, which is driven by waves in the horizontal degree of freedom to rotate, thus rotating the rotor shaft. During rotor shaft rotation, the magnets at the rotor's ends periodically attract or repel the magnets in the stator, causing the piezoelectric sheets to periodically deform, thereby achieving piezoelectric power generation. This effectively matches the electrical output power with the wave excitation frequency, improving energy conversion efficiency. Furthermore, unlike traditional turbines that require parallel alignment with the water flow direction to achieve maximum conversion efficiency, the vertical water turbine of this invention can receive water flow energy perpendicular to its axis, resulting in a simple structure and low manufacturing cost. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the multi-degree-of-freedom composite wave energy converter in an embodiment.

[0026] Figure 2 This is a schematic diagram of the structure of the first power generation component and the third power generation component mounted on the lower surface of the motor support platform and the inner ring of the sliding sleeve, as shown in the embodiment.

[0027] Figure 3 This is a schematic diagram of the structure of the second power generation component mounted on the upper surface of the nanoplatform and the fourth power generation component outside the second mounting shaft, as shown in the embodiment.

[0028] Figure 4 A schematic diagram of the piezoelectric generator of the multi-degree-of-freedom composite wave energy converter in an embodiment;

[0029] Figure 5 A schematic diagram of the power generation process of a piezoelectric generator as an example;

[0030] Figure 6 This is a schematic diagram of the power generation process of a multi-degree-of-freedom composite wave energy converter as an example. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments.

[0032] Please see Figures 1-6This embodiment provides a multi-degree-of-freedom composite wave energy converter, including a mounting frame and a power generation assembly. The power generation assembly includes an electromagnetic power generation unit, a nano-triboelectric power generation unit, and a piezoelectric power generation unit. The electromagnetic power generation unit includes a gravity pendulum and an electromagnetic generator. The gravity pendulum 1 is rotatably mounted on the mounting frame around the center of gravity axis of the wave energy converter, and one end of it is connected to the rotor of the electromagnetic generator. The nano-triboelectric power generation unit includes several power generation components made of frictional materials. The power generation components are mounted on the mounting frame, and under the action of external force, relative motion occurs between the power generation components to generate electrical energy. The piezoelectric power generation unit includes a piezoelectric generator 9 and a water turbine 8. The rotor shaft of the piezoelectric generator is connected to the water turbine. The rotor of the piezoelectric generator is made of piezoelectric material, and magnets are respectively provided on the rotor and stator.

[0033] The mounting frame in this embodiment includes a motor support platform 12, a nano-platform 7, and a mounting shaft. The motor support platform 12 and the nano-platform 7 are vertically mounted to the mounting shaft through through holes in their respective centers, and the motor support platform and the nano-platform are arranged relatively parallel to each other. An electromagnetic power generation unit is mounted on the upper side of the motor support platform, and a nano-triboelectric power generation unit is mounted on the upper side of the nano-platform. A piezoelectric power generation unit is mounted on the bottom of the nano-platform. In this embodiment, four mounting seats 3 are evenly distributed around the circumference of the mounting shaft on the motor support platform 12, and an electromagnetic generator 6 is mounted on each mounting seat. The gravity pendulum 1 is 3D printed and includes an integrally formed mounting plate and a gravity block. The mounting plate is rotatably mounted to the mounting shaft through bearings 2, and the plate body extends at least to the outside of the mounting seat. The gravity block is mounted on the outer plate body of the mounting plate, and two universal balls 11 are installed between the bottom of the gravity block and the motor support platform to support the gravity pendulum, so as to avoid the gravity pendulum tilting due to the center of gravity offset, and to convert the sliding friction loss of the gravity pendulum into rolling friction loss. In addition, the mounting plate in this embodiment is provided with an internal gear ring 4 on its inner side, and the rotor of the electromagnetic generator 6 is provided with a connecting gear 5. The connecting gear 5 meshes with the gear teeth of the internal gear ring 4, and the gear transmission ratio between the gear teeth of the internal gear ring and the connecting gear is 20:1, with a module of 0.5.

[0034] Furthermore, the mounting shaft in this embodiment includes a first mounting shaft 13, a sliding sleeve 15, and a second mounting shaft 14. The first mounting shaft 13 has a hollow structure with a bottom opening, and the sliding sleeve 15 is installed on the bottom opening side. The second mounting shaft 14 is slidably mounted to the bottom opening of the first mounting shaft via the sliding sleeve. The motor support platform 12 is mounted on the shaft body on the opening side of the first mounting shaft, and the nano platform 7 is mounted on the shaft body on the side of the second mounting shaft away from the first mounting shaft. In this embodiment, the motor support platform and the nano platform are respectively provided with four sets of corresponding mounting grooves 16 on their opposite surfaces, and the mounting grooves are evenly distributed along the circumference of their respective platform through holes. A spring 10 is installed between each set of mounting grooves. In addition, the power generation components in this embodiment include a first power generation component 18, a second power generation component 19, a third power generation component 20, and a fourth power generation component. The first power generation component 18 is mounted on the surface of the motor support platform facing the nanoplatform, and from top to bottom includes a first insulating layer 180, a first metal layer 181, and a first nanofriction layer 182. The second power generation component is mounted on the surface of the nanoplatform facing the motor support platform, and from top to bottom includes a second metal layer 190 and a second insulating layer 191. The third power generation component is mounted on the outer side of the second mounting shaft and includes a third metal layer. The fourth power generation component is mounted on the inner ring of the sliding sleeve and includes a second nanofriction layer. In this embodiment, the first metal layer, the second metal layer, and the third metal layer are all copper layers; the first nanofriction layer and the second nanofriction layer are both polytetrafluoroethylene layers.

[0035] In addition, the piezoelectric generator 9 of this embodiment is fixedly mounted on the bottom surface of the nanoplatform. Three sets of first magnets 91 are evenly distributed circumferentially on the inner side of its stator 90. The rotor shaft 92 extends outward along the vertical axis with the same number of rotors 93 as the first magnets. The three rotors are evenly distributed circumferentially along the rotor shaft, and the rotors are made of piezoelectric sheets. A second magnet 94 is provided at the end of the rotor facing the stator. Each set of first and second magnets includes two magnets with different magnetic properties. The two magnets of the first magnet are attached together, and the two magnets of the second magnet are respectively mounted on both sides of the end of the piezoelectric sheet. Specifically, in this embodiment, the six magnets of the three rotors are arranged in a clockwise direction along the circumference in the order of magnetic NSNSNS, and the six magnets mounted on the stator are also arranged in a clockwise order of NSNSNS. Assuming the rotor shaft rotates clockwise, initially, there is no phase difference between the magnets of the piezoelectric sheet and the stator magnets. Figure 3 As shown. The power generation process of a piezoelectric generator is as follows. Figure 4As shown, the water turbine converts the impact energy of the wave flow into rotational motion, driving three rotors, i.e., piezoelectric elements, to rotate. Taking the S-pole magnet at the end of one of the piezoelectric elements as an example, when it first approaches the stator magnet, the S-pole of the piezoelectric element deforms under the repulsive force of the magnet, generating a current. After passing the stator magnet, the N-pole magnet of the piezoelectric element approaches the N-pole magnet of the stator, and the piezoelectric element deforms again under the repulsive force of the magnet, generating a current. This process continues, and during one rotation of the same rotor, each piezoelectric element deforms six times, with the direction of the current changing before and after each pass over the stator magnet.

[0036] Furthermore, the water turbine in this embodiment includes a mounting base and three turbine blades; the mounting base is fixedly mounted to the rotor shaft of the piezoelectric generator through the center of the base body, and three mounting rods with axes perpendicular to the mounting base are evenly distributed along the circumference of the center of the base body on the mounting base, and the three turbine blades are mounted on the mounting rods one by one.

[0037] Working principle: The energy harvesting process of the multi-degree-of-freedom composite wave energy converter in this embodiment is as follows: Figure 5 As shown. First, the ocean waves provide a random excitation to the wave energy converter, activating all the power generation units of the wave energy converter. In this embodiment, the wave energy converter enters the rising phase power generation stage driven by the waves. During the rising phase power generation stage, the wave energy converter operates as follows: the wave energy converter deflects under the action of the ocean waves, and the gravity pendulum rotates under the action of gravity. Through gear transmission via the internal gear ring and connecting gears, it drives the rotor of the electromagnetic generator to rotate, thereby cutting magnetic field lines to generate electricity. Meanwhile, the wave energy converter in this embodiment is subjected to the thrust of the wave parallel to the mounting axis. The wave energy converter generates accelerated motion in the vertical degree of freedom of the wave. Due to inertia, the upper part of the wave energy converter, including the electromagnetic power generation unit and the motor support platform, will compress the spring, thereby providing an upward force of the gravity pendulum. The upper part drives the first mounting axis to slide towards the second mounting axis. As a result, during the spring compression process, the upper surface of the nano-platform and the lower surface of the motor support platform will come into contact with each other, and the first power generation component and the second power generation component will generate electricity through contact. At the same time, during the spring compression process, the third power generation component on the outer side of the second mounting axis and the fourth power generation component on the inner ring of the sliding sleeve will slide and rub against each other to generate electrical energy, thereby realizing the charge transfer of the nano-triboelectric generator.

[0038] When the wave energy converter in this embodiment begins to decelerate in the vertical degree of freedom of the wave, the upper component begins to reset under the action of gravity and spring force. The motor support platform and the nano-platform begin to separate, and the first mounting shaft and the second mounting shaft begin to separate, thereby driving the power generation component of the nano-triboelectric generator to move relative to each other again, thus generating current again. At the same time, during the rising phase of the wave energy converter, the wave water flow perpendicular to the axis of the piezoelectric generator rotor drives the water turbine to rotate the rotor, i.e., the piezoelectric sheet. The interaction between the magnets on the stator and the rotor causes the piezoelectric sheet to deform and generate electricity.

[0039] After the rising phase, the wave energy converter begins to descend due to gravity, entering the descent phase for power generation. During this descent phase, the wave energy converter's operation is as follows: its center of gravity deflects in the opposite direction to that during the rising phase due to the waves. The gravity pendulum rotates under gravity, driving the electromagnetic generator rotor to rotate via gear meshing, cutting magnetic field lines to generate electricity. Simultaneously, during the descent, the wave energy converter decelerates due to the buoyancy of the waves. During deceleration, inertia causes the upper component to compress the spring again, providing upward force for the gravity pendulum. The upper component drives the first mounting shaft to slide towards the second mounting shaft, again driving the nano-triboelectric generator unit to generate electricity. Finally, as the wave energy converter returns to its initial state, the nano-triboelectric generator's power generation components reset under the spring force, undergoing relative motion again to generate current. Similarly, as in the rising phase, during the descent phase, the wave flow along the axis of the piezoelectric generator rotor drives a water turbine, rotating the piezoelectric elements. The interaction between magnets causes deformation of the piezoelectric elements, generating electricity.

[0040] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A multi-degree-of-freedom composite wave energy converter, comprising a mounting frame and a power generation component, characterized in that: The power generation assembly includes an electromagnetic power generation unit, a nano-triboelectric power generation unit, and a piezoelectric power generation unit. The electromagnetic power generation unit includes a gravity pendulum and an electromagnetic generator. The gravity pendulum is rotatably mounted on a mounting frame around the center of gravity axis of the wave energy converter, and one end of it is connected to the rotor of the electromagnetic generator. The nano-triboelectric power generation unit includes several power generation components made of frictional materials. These components are mounted on the mounting frame, and under external force, relative motion occurs between them to generate electrical energy. The piezoelectric power generation unit includes a piezoelectric generator and a water turbine. The rotor shaft of the piezoelectric generator is connected to the water turbine. The rotor of the piezoelectric generator is made of piezoelectric material, and magnets are respectively provided on the rotor and stator. The mounting bracket includes a motor support platform, a nano-platform, and a mounting shaft; the motor support platform and the nano-platform are vertically mounted to the mounting shaft by having through holes in their respective centers, and the motor support platform and the nano-platform are arranged relatively parallel to each other; the electromagnetic power generation unit is mounted on the upper side of the motor support platform, the nano-triboelectric power generation unit is mounted on the upper side of the nano-platform, and the piezoelectric power generation unit is mounted on the bottom of the nano-platform; The piezoelectric generator is fixedly installed on the bottom surface of the nanoplatform. At least three sets of first magnets are evenly distributed along the circumference of the inner side of its stator. The rotor shaft has the same number of rotors as the first magnets extending outward along the vertical axis. Several rotors are evenly distributed along the circumference of the rotor shaft, and the rotors are made of piezoelectric sheets. The end of the rotor facing the stator is provided with a second magnet. Each set of first magnets and second magnets includes two magnets with different magnetic properties. The two magnets of the first magnet are attached together, and the two magnets of the second magnet are respectively installed on both sides of the end of the piezoelectric sheet.

2. The multi-degree-of-freedom composite wave energy converter according to claim 1, characterized in that, The motor support platform has several first mounting seats evenly distributed around the mounting shaft in the circumferential direction, and each first mounting seat is equipped with the electromagnetic generator; the gravity pendulum is rotatably mounted on the mounting shaft through bearings, and the gravity pendulum is connected to the rotor of the electromagnetic generator through connecting gears.

3. A multi-degree-of-freedom composite wave energy converter according to claim 2, characterized in that, The gravity pendulum includes an integrally formed mounting plate and a gravity block; the mounting plate is rotatably mounted on the mounting shaft via bearings, and the plate body extends at least to the outer side of the first mounting seat; the gravity block is mounted on the outer plate body of the mounting plate, and a rolling element is installed between the bottom of the gravity block and the motor support platform; an internal gear ring is provided on the inner side of the mounting plate, and the rotor of the electromagnetic generator is provided with a connecting gear, which meshes with the internal gear ring gear, and the gear transmission ratio between the internal gear ring and the connecting gear is 20:

1.

4. A multi-degree-of-freedom composite wave energy converter according to claim 1, characterized in that, The mounting shaft includes a first mounting shaft, a sliding sleeve, and a second mounting shaft; the first mounting shaft has a hollow structure with a bottom opening, and the sliding sleeve is installed on the bottom opening side; the second mounting shaft is slidably mounted on the bottom opening of the first mounting shaft through the sliding sleeve; the motor support platform is mounted on the shaft body on the opening side of the first mounting shaft, and the nano platform is mounted on the shaft body of the second mounting shaft on the side away from the first mounting shaft.

5. A multi-degree-of-freedom composite wave energy converter according to claim 4, characterized in that, The motor support platform and the nano platform are respectively provided with several sets of corresponding mounting grooves on their opposite surfaces, and the mounting grooves are evenly distributed along the circumference of their respective platform through holes; an elastic element is installed between each set of mounting grooves.

6. A multi-degree-of-freedom composite wave energy converter according to claim 4, characterized in that, The plurality of power generation components include a first power generation component, a second power generation component, a third power generation component, and a fourth power generation component; the first power generation component is mounted on the surface of the motor support platform facing the nanoplatform, and from top to bottom includes a first insulating layer, a first metal layer, and a first nanofriction layer; the second power generation component is mounted on the surface of the nanoplatform facing the motor support platform, and from top to bottom includes a second metal layer and a second insulating layer; the third power generation component is mounted on the outer side of the second mounting shaft, and includes a third metal layer; the fourth power generation component is mounted on the inner ring of the sliding sleeve, and includes a second nanofriction layer.

7. A multi-degree-of-freedom composite wave energy converter according to claim 6, characterized in that, The first metal layer, the second metal layer, and the third metal layer are all copper layers; the first nano-friction layer and the second nano-friction layer are both polytetrafluoroethylene layers.

8. A multi-degree-of-freedom composite wave energy converter according to claim 1, characterized in that, The water turbine includes a second mounting base and several turbine blades; the second mounting base is fixedly mounted on the rotor shaft of the piezoelectric generator through the center of the base body, and several mounting rods with axes perpendicular to the second mounting base are evenly distributed along the circumference of the center of the base body on the second mounting base, and several turbine blades are mounted on the mounting rods one by one.

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