Multi-degree-of-freedom composite wave energy converter

Abstract

The invention relates to a multi-degree-of-freedom composite wave energy converter, and belongs to the technical field of wave power generation. Comprising a mounting frame and a power generation assembly, and the power generation assembly comprises an electromagnetic power generation unit, a nanometer friction 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 rotationally mounted on the mounting frame around the gravity center axis of the wave energy converter, and one end of the gravity pendulum is connected with a rotor of the electromagnetic generator; the nanometer friction power generation unit comprises a plurality of power generation parts made of friction materials, the power generation parts are installed on the installation frame, and under the action of external force, the power generation parts move relatively to generate electric energy; the piezoelectric power generation unit comprises a piezoelectric generator and a water flow turbine; a rotor shaft of the piezoelectric generator is connected with the water flow turbine, a rotor of the piezoelectric generator is made of piezoelectric materials, and magnets are arranged on the rotor and a stator respectively. The multi-degree-of-freedom wave capturing device can comprehensively and efficiently capture waves in multiple degrees of freedom, and is high in energy conversion efficiency and wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of wave power generation, and in particular to a multi-degree-of-freedom composite wave energy converter. Background Art

[0002] The ocean covers over 70% of the Earth's surface and holds abundant resources for future sustainable development. Long-term, continuous, and multidisciplinary observations of the vast ocean are not only of strategic and scientific importance to global scientific research, marine resource development, and marine environmental monitoring, but also play a vital role in promoting global climate change response and the sustainable use of the ocean. Currently, thousands of ocean observation platforms equipped with a variety of sensors are in operation, aiming to build a global three-dimensional observation network. However, these systems require significant energy to ensure long-term stable operation and capture a wide range of sensor data. Relying solely on high-capacity batteries and low power consumption is insufficient to support the long-term mobile operation of observation platforms, especially when the platforms are far from land, where battery replacement becomes extremely difficult. Therefore, developing ocean energy harvesting technologies to enable long-term, self-sustaining operation of observation systems has become an urgent issue.

[0003] As one of the most abundant renewable energy sources in the ocean, wave energy offers advantages such as wide distribution, low acquisition cost, and unaffected by day and night cycles and atmospheric circulation. It is 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 existing technologies from efficiently capturing and utilizing wave energy. 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 converters utilize the kinetic and potential energy of water waves through efficient energy capture mechanisms, and employ electromagnetic, piezoelectric, or frictional methods to convert mechanical energy into electrical energy. For example, in the existing technology, some researchers have designed a gravity pendulum electromagnetic wave energy harvesting system, which captures wave energy through an upright horizontal pendulum structure, and its output electrical energy waveform can reflect the dynamics of the waves; some researchers have proposed a piezoelectric wave energy harvester using a cylindrical and conical floating structure, which drives the piezoelectric cantilever beam to generate high-frequency vibration power through the up and down movement of the low-frequency floating body and magnetic coupling; and some researchers have designed a friction nanogenerator with a gyroscopic structure for harvesting low-frequency wave energy, whose internal and external power generation units can move independently in different directions, thus avoiding mutual interference.

[0004] Among the three commonly used energy harvesting methods, electromagnetic energy harvesting offers low voltage, high current, and low system internal resistance. However, it requires a mechanical mechanism to convert wave excitation into high-frequency motion to improve electromechanical conversion efficiency. Piezoelectric energy harvesting offers the advantages of simple structure, high energy density, and low cost, but its output power is affected by the excitation frequency, typically requiring mechanical modulation to match the excitation frequency with the piezoelectric resonant frequency to increase output power. Frictional nanoenergy harvesting exhibits higher energy conversion efficiency at low frequencies, offering advantages such as high power density, high efficiency, low weight, and low manufacturing cost. However, its high output voltage, low current, and high internal resistance hinder effective energy utilization. Currently, most ocean 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 overtopping, oscillating water column, and oscillating body, typically focus solely on single-degree-of-freedom energy harvesting perpendicular to the sea surface, neglecting multi-directional energy harvesting, resulting in low energy capture efficiency. Therefore, developing a wave energy converter that can collect wave energy in multiple directions and improve energy conversion efficiency has become one of the key technologies in the field of ocean energy harvesting. Summary of the Invention

[0005] The object of the present invention is to provide a multi-degree-of-freedom composite wave energy converter to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, the present invention provides a multi-degree-of-freedom composite wave energy converter that has multiple power generation modes and converts wave energy in multiple degrees of freedom. By designing a conversion mechanism that can adapt to multi-directional and low-frequency waves, the problems of low wave energy capture efficiency and insufficient energy conversion in the prior art are solved. The multi-degree-of-freedom composite wave energy converter of the present invention aims to achieve comprehensive and efficient capture of wave energy by designing multiple power generation units and a multi-degree-of-freedom energy collection 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 the present invention mainly includes two technical ideas and designs: (1) The first technical idea is to realize the design of a multi-degree-of-freedom ocean wave energy conversion mechanism. The role of the ocean wave energy converter is to efficiently capture and convert the kinetic energy and potential energy of the waves, thereby converting the complex mechanical motion of the 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 the waves, resulting in low energy capture efficiency. Therefore, the present invention adopts a multi-degree-of-freedom conversion mode, which responds to the multi-directional motion of the waves in multiple degrees of freedom at the same time through multiple independent or coupled power generation units. The specific scheme is to use an electromagnetic power generation unit including a gravity pendulum to convert the energy of the wave's rotational degree of freedom; use a nano-friction power generation unit to convert the energy of the wave's vertical degree of freedom; and use a piezoelectric power generation unit including a water turbine to convert the energy of the wave's horizontal degree of freedom.

[0008] (2) The second technical idea is to realize the conversion of mechanical energy of wave energy converter into electrical energy. Traditional electromagnetic energy collection 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-friction power generation can achieve more efficient energy collection under low frequency and small vibration conditions. The charge difference generated by the relative movement between friction materials can be converted into electrical energy. Piezoelectric generator is a device that converts mechanical energy (such as vibration or pressure change) into electrical energy. Its main advantages are high energy conversion and long-term stability. Nano-friction 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 collection technology to improve the capture and conversion efficiency of wave energy, thereby achieving more comprehensive and efficient energy collection in a changing marine environment. In order to improve the efficiency of wave energy collection and realize sensor driving, the present invention uses an electromagnetic generator to collect the rotational freedom energy converted by the gravity pendulum; uses a nano-friction power generation unit to collect waves to drive the wave energy converter to move in the vertical freedom degree, so as to drive the relative movement between the power generation components made of friction materials to generate electricity for energy conversion; and uses a pressure piezoelectric power generation unit to collect the horizontal freedom energy converted by the water flow turbine perpendicular to the installation axis.

[0009] Based on the above technical ideas, the present invention provides the following technical solutions: a multi-degree-of-freedom composite wave energy converter, comprising a mounting frame and a power generation assembly, the power generation assembly comprising an electromagnetic power generation unit, a nano-friction 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 mounted on the mounting frame and rotates around the axis of gravity of the wave energy converter, and one end of the gravity pendulum is connected to the rotor of the electromagnetic generator; the nano-friction power generation unit comprises a plurality of power generation components made of friction material, the power generation components are mounted on the mounting frame, and under the action of external force, relative movement occurs between the power generation components 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 stator.

[0010] Preferably, the mounting frame includes a motor support platform, a nanoplatform and a mounting shaft; the motor support platform and the nanoplatform are installed on the mounting shaft vertically by opening through holes in the centers of their respective platforms, and the motor support platform and the nanoplatform are arranged relatively parallel; the electromagnetic power generation unit is installed on the motor support platform located on the upper side, and the nano-friction power generation unit is installed on the upper side of the nanoplatform; the piezoelectric power generation unit is installed on the bottom of the nanoplatform.

[0011] Preferably, a plurality of mounting seats are evenly spaced around the mounting axis on the motor support platform, and an electromagnetic generator is installed on each mounting seat; the gravity pendulum is rotatably mounted on the mounting axis through a bearing, and the gravity pendulum is connected to the rotor of the electromagnetic generator through a connecting gear.

[0012] Preferably, the gravity pendulum includes an integrally formed mounting plate and a gravity block; the mounting plate is rotatably mounted on the mounting shaft through a bearing, and the plate body of the mounting plate 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 a rolling element is installed between the bottom of the gravity block and the motor support platform; an inner ring gear 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 is meshed with the inner ring gear, and the gear transmission ratio of the inner ring gear and the connecting gear is 20:1.

[0013] Preferably, the mounting shaft includes a first mounting shaft, a sliding sleeve and a second mounting shaft; the first mounting shaft is a hollow structure with an opening at the bottom, and a sliding sleeve is installed on the side of the bottom opening; the second mounting shaft is slidably installed on the bottom opening of the first mounting shaft through the sliding sleeve; the motor support platform is installed on the shaft body on the opening side of the first mounting shaft, and the nano-platform is installed on the shaft body on the side of the second mounting shaft away from the first mounting shaft.

[0014] Preferably, a plurality of groups of corresponding mounting grooves are provided on the opposite surfaces of the motor support platform and the nano-platform, and the mounting grooves are evenly spaced along the circumference of their respective platform through holes; and elastic members are installed between each group of mounting grooves.

[0015] 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 installed on the surface of the motor support platform facing the nano platform, and includes a first insulating layer, a first metal layer and a first nano friction layer from top to bottom; the second power generation component is installed on the surface of the nano platform facing the motor support platform, and includes a second metal layer and a second insulating layer from top to bottom; the third power generation component is installed on the outside of the second mounting shaft, and includes a third metal layer; the fourth power generation component is installed on the inner ring of the sliding sleeve, and includes a second nano friction layer.

[0016] Preferably, the first metal layer, the second metal layer and the third metal layer are all copper layers; and the first nano-friction layer and the second nano-friction layer are both polytetrafluoroethylene layers.

[0017] Preferably, the piezoelectric generator is fixedly mounted on the bottom surface of the nano-platform, and at least three groups of first magnets are evenly distributed along the circumference on 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 direction. 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 group of first magnets and second magnets respectively includes two magnets with different magnetic properties, and the two magnets of the first magnet are bonded together, and the two magnets of the second magnet are respectively installed on both sides of the end of the piezoelectric sheet.

[0018] Preferably, the water turbine includes a mounting seat and a plurality of turbine blades; the mounting seat is fixedly mounted on the piezoelectric generator rotor shaft through the center of the seat body, and a plurality of mounting rods with axes perpendicular to the mounting seat are evenly distributed along the center circumference of the seat body on the mounting seat, and the plurality of turbine blades are mounted on the mounting rods one by one. Beneficial effects

[0019] The multi-degree-of-freedom composite wave energy converter of the present invention is equipped with multiple power generation units, including electromagnetic power generation units, nano-friction power generation units and piezoelectric power generation units, to achieve multi-directional response to waves in multiple degrees of freedom at the same time, so as to convert the mechanical energy of waves into electrical energy, thereby achieving comprehensive and efficient capture of wave energy, overcoming the limitations of traditional single-degree-of-freedom systems and single-energy conversion methods on the range and efficiency of wave energy acquisition.

[0020] Based on the above, the electromagnetic power generation unit of the present invention includes a gravity pendulum and an electromagnetic generator, wherein 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 a bearing, and the gravity block is mounted on the outside of the mounting plate, so that when the center of gravity of the multi-degree-of-freedom composite wave energy converter of the present invention is deflected by the wave, the gravity block of the gravity pendulum can rotate around the mounting axis under the action of gravity. At the same time, an internal gear ring containing gear teeth is provided on the mounting plate, and a mounting seat is provided on the motor support platform for mounting the electromagnetic generator, wherein the rotor shaft of the electromagnetic generator is gear-engaged with the internal gear ring of the mounting plate via a connecting gear, so that when the gravity pendulum rotates, the gear engagement drives the rotor of the electromagnetic generator to rotate to generate electricity, thereby converting the energy of the wave in the rotational degree of freedom into electricity. A similar technical approach is to set a nano-platform parallel to the motor support platform on the mounting axis of the mounting frame, set an elastic member between the two platforms, and set the mounting axis between the two platforms as a telescopic structure, so that when the waves drive the multi-degree-of-freedom composite wave energy converter of the present invention to move in the vertical degree of freedom, due to the effects of inertia and wave buoyancy, relative movement occurs between the motor support platform and the nano-platform, thereby driving the power generation components made of friction material to generate electricity. The same technical approach is to set a piezoelectric power generation unit, which includes a piezoelectric generator and a water turbine, and use the waves to drive the water turbine to rotate along the horizontal degree of freedom, so as to drive the rotor made of piezoelectric material to rotate and generate electricity. The multi-degree-of-freedom composite wave converter of the present invention can convert the complex mechanical motion of waves into usable regular mechanical motion in multiple degrees of freedom, thereby improving the energy capture efficiency.

[0021] Based on the above, to improve the energy conversion efficiency of each power generation unit, the electromagnetic power generation unit of the present invention has a plurality of mounting brackets for mounting multiple electromagnetic generators, which are evenly spaced along the circumference of the motor support platform. Furthermore, the transmission ratio between the teeth of the inner ring gear of the mounting plate and the connecting gear of the electromagnetic generator rotor is set to 20:1. This ensures that when waves drive the center of gravity of the wave converter of the present invention to deflect, the rotation of the gravity pendulum drives the electromagnetic generator to generate electricity. This allows the low-frequency motion of the waves to drive the small mechanical displacement of the gravity pendulum to generate high-frequency motion, thereby improving power generation efficiency and energy conversion efficiency. The nano-friction power generation unit of the present invention can achieve more efficient energy collection under low-frequency and small wave vibrations. 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 plate into electrical energy, with the main advantages of efficient energy conversion and long-term stability. In addition, the nano-friction power generation unit and piezoelectric power generation unit of the present invention have high energy conversion efficiency under low power, high-frequency changes and small-amplitude vibrations, and can complement the energy collection technology of the electromagnetic power generation unit to improve the capture and conversion efficiency of wave energy, thereby achieving more comprehensive and efficient energy collection in a changing marine environment.

[0022] Based on the above, the nano-triboelectric power generation unit of the present invention comprises several power generation components, including 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 comprises, from top to bottom, a first insulating layer, a first metal layer, and a first nano-triboelectric layer. The second power generation component is mounted on the surface of the nano-platform facing the motor support platform and comprises, from top to bottom, 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 comprises a third metal layer. The fourth power generation component is mounted on the inner ring of the sliding sleeve and comprises a second nano-triboelectric layer. This allows the motor support platform to move vertically toward the nano-platform due to inertia under wave drive, driving the first and second power generation components to generate contact power. Simultaneously, during the relative motion of the two platforms, the first mounting shaft moves toward the second mounting shaft, driving the sliding triboelectric power generation between the third and fourth power generation components. This results in a high energy collection rate and improved energy utilization. The first power generation component includes a first insulating layer for electrical isolation, a first metal layer (copper), which improves electrical conductivity and effectively transmits electrical energy, and a first nano-friction layer (PTFE) for energy conversion. The second power generation component's second metal layer (copper) and second insulating layer are used to contact and separate with the PTFE layer to generate current while also providing good electrical conductivity.

[0023] Based on the above, the piezoelectric power generation unit of the present invention uses piezoelectric sheets to form a rotor for energy conversion. Magnets with opposite magnetic properties are mounted on either side of the distal end of each piezoelectric sheet, while first magnets are spaced apart circumferentially on the stator, equal in number to the piezoelectric sheets. Each set of first magnets includes two magnets bonded together and with opposite magnetic properties. The rotor shaft of the piezoelectric generator is equipped with a water turbine to drive the water turbine to rotate in the horizontal degree of freedom through waves, thereby driving the rotor shaft to rotate. During the rotation of the rotor shaft, the magnets at the rotor ends and the magnets in the stator are magnetically attracted or repelled in an anti-periodic manner, causing the piezoelectric sheets to deform periodically, thereby achieving piezoelectric power generation and effectively matching the electrical output power with the wave excitation frequency to improve energy conversion efficiency. Furthermore, the water turbine of the present invention is used to convert water flow energy in the horizontal degree of freedom of waves. Unlike traditional turbines that require a turbine to be parallel to the water flow direction to achieve maximum conversion efficiency, the vertical water turbine of the present invention can receive water flow energy perpendicular to the axis, resulting in a simple structure and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of a multi-degree-of-freedom composite wave energy converter according to an embodiment; Figure 2 Schematic diagram of the structure of the first power generation component installed on the lower surface of the motor support platform and the third power generation component on the inner ring of the sliding sleeve in the embodiment; Figure 3 Schematic diagram of the structure of the second power generation component installed on the upper surface of the nano-platform and the fourth power generation component outside the second installation axis of the embodiment; Figure 4 A schematic structural diagram of a piezoelectric generator of a multi-degree-of-freedom composite wave energy converter according to an embodiment; Figure 5 Schematic diagram of the power generation process of the piezoelectric generator of the embodiment; Figure 6 Schematic diagram of the power generation process of the multi-degree-of-freedom composite wave energy converter according to an embodiment. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0026] See also Figures 1-6The present embodiment provides a multi-degree-of-freedom composite wave energy converter, comprising a mounting frame and a power generation assembly, the power generation assembly comprising an electromagnetic power generation unit, a nano-friction 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 1 is mounted on the mounting frame and rotates around the axis of gravity of the wave energy converter, and one end of the gravity pendulum is connected to the rotor of the electromagnetic generator; the nano-friction power generation unit comprises a plurality of power generation components made of friction material, the power generation components are mounted on the mounting frame, and under the action of external force, relative movement occurs between the power generation components to generate electrical energy; the piezoelectric power generation unit comprises 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 the stator.

[0027] The mounting frame of 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 on the mounting shaft by opening a through hole in the center of each platform, and the motor support platform and the nano-platform are arranged relatively parallel. The electromagnetic power generation unit is mounted on the upper motor support platform, and the nano-friction power generation unit is mounted on the upper side of the nano-platform. The piezoelectric power generation unit is mounted on the bottom of the nano-platform. In this embodiment, the motor support platform 12 has four mounting seats 3 spaced evenly around the circumference of the mounting shaft, each of which is mounted with an electromagnetic generator 6. The gravity pendulum 1 is completed by 3D printing and includes an integrally formed mounting plate and a gravity block. The mounting plate is rotatably mounted on the mounting shaft via a bearing 2, and the mounting plate extends at least to the outside of the mounting seat. The gravity block is mounted on the outer plate 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, thereby preventing the gravity pendulum from tilting due to the offset center of gravity and converting the sliding friction loss of the gravity pendulum into rolling friction loss. In addition, an inner ring gear 4 is provided on the inner side of the mounting plate of this embodiment, and a connecting gear 5 is provided on the rotor of the electromagnetic generator 6. The connecting gear 5 is engaged with the gear teeth of the inner ring gear 4, and the gear transmission ratio of the gear teeth of the inner ring gear and the connecting gear is 20:1, and the module is 0.5.

[0028] Furthermore, the mounting shaft of this embodiment includes a first mounting shaft 13, a sliding sleeve 15, and a second mounting shaft 14. The first mounting shaft 13 is a hollow structure with an open bottom, and the sliding sleeve 15 is mounted on the side of the bottom opening. 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 open side of the first mounting shaft, and the nano-platform 7 is mounted on the side of the second mounting shaft away from the first mounting shaft. Four sets of corresponding mounting grooves 16 are provided on the opposing surfaces of the motor support platform and the nano-platform of this embodiment, and the mounting grooves are evenly spaced along the circumference of the respective platform through-holes. Springs 10 are installed between each set of mounting grooves. In addition, the several power generation components of 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 nano-platform and comprises, from top to bottom, a first insulating layer 180, a first metal layer 181, and a first nano-friction layer 182. The second power generation component is mounted on the surface of the nano-platform facing the motor support platform and comprises, from top to bottom, a second metal layer 190 and a second insulating layer 191. The third power generation component is mounted on the outside of the second mounting shaft and comprises a third metal layer. The fourth power generation component is mounted on the inner ring of the sliding sleeve and comprises a second nano-friction layer. In this embodiment, the first, second, and third metal layers are all copper layers; the first and second nano-friction layers are both polytetrafluoroethylene layers.

[0029] In addition, the piezoelectric generator 9 of this embodiment is fixedly mounted on the bottom surface of the nano-platform, and three groups of first magnets 91 are evenly spaced along the circumference on the inner side of the stator 90, and the rotor shaft 92 is provided with rotors 93 of the same number as the first magnets extending outward in the direction perpendicular to the axis. The three rotors are evenly spaced along the circumference of 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 group of first magnets and second magnets includes two magnets with different magnetic properties, and the two magnets of the first magnet are bonded together as a whole, and the two magnets of the second magnet are respectively installed on both sides of the end of the piezoelectric sheet. Specifically, the six magnets of the three rotors of this embodiment are arranged in the order of magnetic properties NSNSNS along the circumference in a clockwise direction, and the six magnets installed on the stator part are also arranged in the order of NSNSNS in the clockwise direction. Assuming that the rotor shaft rotates clockwise, in the initial state, there is no phase difference between the magnets of the piezoelectric sheet and the magnets of the stator, such as Figure 3 The power generation process of the piezoelectric generator is as follows Figure 4As shown, the water turbine converts the impact energy of waves and water flow into rotational motion, which drives the three rotors, namely piezoelectric plates, to rotate. For example, when an S-pole magnet at the end of one of the piezoelectric plates first approaches the stator magnet, the S-pole of the piezoelectric plate deforms under the repulsive force of the same magnetic magnet, generating current. After passing the stator magnet, the N-pole magnet of the piezoelectric plate approaches the N-pole magnet of the stator, and the piezoelectric plate deforms again under the repulsive force of the magnets, generating current. Similarly, during the same rotor's complete rotation, its single piezoelectric plate deforms six times, and the direction of the current changes each time it passes the stator magnet.

[0030] Furthermore, the water turbine of this embodiment includes a mounting seat and three turbine blades; the mounting seat is fixedly mounted on the piezoelectric generator rotor shaft through the center of the seat body, and three mounting rods with axes perpendicular to the mounting seat are evenly distributed along the center circumference of the seat body on the mounting seat, and the three turbine blades are mounted on the mounting rods one by one.

[0031] Working principle: The energy collection process of the multi-degree-of-freedom composite wave energy converter in this embodiment is as follows: Figure 5 As shown. First, the waves provide a random excitation to the wave energy converter, activating all of the converter's power generation units. The wave energy converter of this embodiment is driven by the waves to enter the ramp-up power generation phase. During the ramp-up power generation phase, the wave energy converter operates as follows: the wave energy converter deflects under the action of the waves, causing the gravity pendulum to rotate under the influence of gravity. This rotation, driven by the gear transmission of the inner ring gear and the connecting gear, drives the electromagnetic generator rotor to rotate, cutting the magnetic flux lines to generate electricity. At the same time, the wave energy converter of this embodiment will be affected by the wave thrust parallel to the installation axis, and the wave energy converter will generate accelerated motion in the vertical degree of freedom of the wave. Due to the effect of inertia, the upper components 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 for the gravity pendulum. The upper components drive the first installation axis to slide toward the second installation axis. Therefore, during the spring compression process, the upper surface of the nanoplatform and the lower surface of the motor support platform will contact each other, and the first power generation component and the second power generation component will contact to generate electricity. At the same time, during the spring compression process, the third power generation component on the outside of the second installation axis and the fourth power generation component on the inner ring of the sliding sleeve will slide and rub to generate electrical energy, thereby realizing the charge transfer of the nano friction generator.

[0032] When the wave energy converter of this embodiment begins to decelerate in the wave's perpendicular degree of freedom, gravity and spring forces cause the upper component to reset, the motor support platform and the nanoplatform to separate, and the first and second mounting shafts to separate, driving the nano-friction generator's generating components into relative motion again, thereby regenerating current. Simultaneously, during the wave energy converter's ramp-up phase, wave currents perpendicular to the axis of the piezoelectric generator's rotor drive the water turbine, which in turn rotates the rotor, i.e., the piezoelectric disc. The interaction between the magnets on the stator and rotor causes the piezoelectric disc to deform, generating electricity.

[0033] After the rising phase, the wave energy converter begins to descend due to gravity, entering the descending phase of power generation. During the descending phase, the wave energy converter operates as follows: the center of gravity of the wave energy converter deflects in the opposite direction to the rising phase under the influence of waves. The gravity pendulum rotates under the influence of gravity, and through gear meshing, it drives the electromagnetic generator rotor to rotate, cutting magnetic flux lines to generate electricity. Simultaneously, during the descent, the wave energy converter begins to decelerate due to the buoyancy of the waves. During this deceleration, the upper component compresses the spring again due to inertia, providing an upward force for the gravity pendulum. The upper component drives the first mounting axis to slide toward the second mounting axis, again driving the nano-triboelectric generator to generate electricity. Finally, as the wave energy converter returns to its initial state, the spring force resets the nano-triboelectric generator's generating components, causing relative motion again, generating current. Similarly, during the descending phase, the wave currents along the axis of the piezoelectric generator's rotor shaft drive the water turbine, which rotates the piezoelectric disc. The interaction between the magnets causes the disc to deform, generating electricity.

[0034] As above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present 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 assembly, characterized in that: The power generation component includes an electromagnetic power generation unit, a nano-friction 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 mounted on a mounting frame and rotates around the center of gravity axis of the wave energy converter, and one end of the gravity pendulum is connected to the rotor of the electromagnetic generator; the nano-friction power generation unit includes a plurality of power generation components made of friction material, the power generation components are mounted on the mounting frame, and under the action of external force, relative movement occurs between the power generation components 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.

2. A multi-degree-of-freedom composite wave energy converter according to claim 1, characterized in that: The mounting frame includes a motor support platform, a nano platform and a mounting shaft; the motor support platform and the nano platform are vertically installed on the mounting shaft by opening a through hole in the center of each platform, and the motor support platform and the nano platform are arranged relatively parallel; the electromagnetic power generation unit is installed on the motor support platform located on the upper side, and the nano friction power generation unit is installed on the upper side of the nano platform; the piezoelectric power generation unit is installed at the bottom of the nano platform.

3. A multi-degree-of-freedom composite wave energy converter according to claim 2, characterized in that: The motor support platform is provided with a plurality of mounting seats spaced evenly around the circumferential direction of the mounting shaft, and the electromagnetic generator is mounted on each mounting seat; the gravity pendulum is rotatably mounted on the mounting shaft through a bearing, and the gravity pendulum is connected to the rotor of the electromagnetic generator through a connecting gear.

4. A multi-degree-of-freedom composite wave energy converter according to claim 3, 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 a bearing, and the plate body of the mounting plate 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 a rolling element is installed between the bottom of the gravity block and the motor support platform; an inner ring gear is provided on the inner side of the mounting plate, and the rotor of the electromagnetic generator is provided with a connecting gear, which is engaged with the inner ring gear, and the gear transmission ratio between the inner ring gear and the connecting gear is 20:

1.

5. A multi-degree-of-freedom composite wave energy converter according to claim 2, characterized in that: The mounting shaft includes a first mounting shaft, a sliding sleeve and a second mounting shaft; the first mounting shaft is a hollow structure with an opening at the bottom, and the sliding sleeve is installed on the side of the bottom opening; the second mounting shaft is slidably installed on the bottom opening of the first mounting shaft through the sliding sleeve; the motor support platform is installed on the shaft body on the opening side of the first mounting shaft, and the nano platform is installed on the shaft body on the side of the second mounting shaft away from the first mounting shaft.

6. A multi-degree-of-freedom composite wave energy converter according to claim 5, characterized in that: The motor support platform and the nano platform are respectively provided with a plurality of groups of corresponding mounting grooves on the opposite surfaces thereof, and the mounting grooves are evenly spaced along the circumference of the respective platform through holes; elastic members are installed between each group of mounting grooves.

7. The multi-degree-of-freedom composite wave energy converter according to claim 5, characterized in that: Several 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 installed on the surface of the motor support platform facing the nano platform, and includes a first insulating layer, a first metal layer and a first nano friction layer from top to bottom; the second power generation component is installed on the surface of the nano platform facing the motor support platform, and includes a second metal layer and a second insulating layer from top to bottom; the third power generation component is installed on the outside of the second mounting shaft, and includes a third metal layer; the fourth power generation component is installed on the inner ring of the sliding sleeve, and includes a second nano friction layer.

8. A multi-degree-of-freedom composite wave energy converter according to claim 7, 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.

9. The multi-degree-of-freedom composite wave energy converter according to claim 2, characterized in that: The piezoelectric generator is fixedly mounted on the bottom surface of the nano-platform, and at least three groups of first magnets are evenly distributed along the circumference on 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 direction. 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 group of first magnets and second magnets respectively includes two magnets with different magnetic properties, and the two magnets of the first magnet are bonded together, and the two magnets of the second magnet are respectively installed on both sides of the end of the piezoelectric sheet.

10. A multi-degree-of-freedom composite wave energy converter according to claim 9, characterized in that: The water turbine includes a mounting seat and a plurality of turbine blades; the mounting seat is fixedly mounted on the piezoelectric generator rotor shaft through the center of the seat body, and a plurality of mounting rods with axes perpendicular to the mounting seat are evenly distributed along the center circumference of the seat body, and the plurality of turbine blades are mounted on the mounting rods one by one.

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