A multi-degree-of-freedom wave energy power generation device

Abstract

The present invention discloses a multi-degree-of-freedom wave energy power generation device, belonging to the technical field of wave energy power generation. It comprises a buoy body, the top outer surface of the buoy body is provided with a weather data module, a 3-RSR parallel mechanism is installed inside the buoy body, a battery pack is installed on the top of the 3-RSR parallel mechanism, the battery is connected to a rectifier control unit, and a synchronous generator and a torsion spring are installed at the bottom of the 3-RSR parallel mechanism. The present invention introduces a parallel mechanism as a transmission mechanism, so that the wave energy power generation device can absorb the oscillation energy in three directions of heave, longitudinal swing and pitch at the same time, thereby improving the theoretical upper limit of energy capture power. The wave energy device is miniaturized and placed in marine equipment such as buoys, which can directly power offshore equipment, not only improving the utilization value of electric energy, but also eliminating the difficulty of electric energy transmission. The wave energy power generation device is completely sealed inside the buoy, which can effectively solve problems such as seawater corrosion and improve reliability and stability.

Description

Technical Field

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

[0002] Wave energy is widely distributed in the ocean and is a clean energy source. Compared with new energy sources such as solar energy and wind energy, wave energy not only has a higher energy density, but the wave energy capture process does not depend on weather conditions and can be effectively carried out in more than 90% of the time period. Wave energy power generation device is a device that converts the kinetic energy and potential energy of waves into electrical energy and has broad development prospects.

[0003] According to different energy capture methods, wave energy power generation devices can be divided into three types: oscillating water column type, overriding wave type, and oscillating body type. According to the complexity of the energy conversion process, it can be divided into traditional type and direct drive type. Among them, the more typical one is the direct drive point suction wave energy power generation device, which is much smaller than the wave wavelength, can absorb incident waves from all directions, and has a high capture efficiency, which is suitable for the sea conditions with low wave energy density in my country. The principle of the direct drive point suction wave energy power generation device is: the stator of the linear generator is fixed on the seabed, and the mover is connected to the float (oscillating body). Due to the changing wave force, the float will produce reciprocating motion in the vertical direction, driving the mover and stator to move relative to each other, generating back electromotive force. The direct drive point suction wave energy power generation device has the advantages of simple structure, stable and effective operation, few transmission links, high energy conversion efficiency, and easy implementation of control algorithms.

[0004] For wave energy power generation devices, the most important evaluation index is the energy absorption power. Under the action of the incident wave, if only the oscillation in the heave direction is considered, that is, the oscillating body only moves up and down, a symmetrical circular radiation wave will be generated on the wave surface. If the heave radiation wave is opposite in phase to the incident wave, it will interfere destructively with the incident wave, causing the amplitude of the incident wave after passing through the floating body to decrease, thereby causing the kinetic energy to decrease. It is generally believed that this part of the energy reduced by the wave is absorbed by the oscillation system. Since the incident wave can be approximately regarded as a parallel wave, the heave radiation wave of the rotating floating body is a symmetrical circular wave and cannot completely destructively interfere with the incident wave. In fact, according to wave theory, if only the heave direction is considered, the upper limit of the incident wave energy that can be absorbed is 50%. If the floating body performs a swinging motion, an antisymmetric radiation wave will be generated. If the ratio of heave and swing motion can be properly controlled, in theory, the incident wave after passing through the floating body can be almost completely eliminated, and the energy of the incident wave is completely absorbed. Therefore, considering the movement in the swaying direction is crucial to improving the energy absorption capacity of the wave energy power generation device. The wave energy power generation device urgently needs to introduce a mechanism to simultaneously absorb the oscillation energy of the heaving motion and the swaying motion.

[0005] The main drawback of existing wave energy power generation devices is the low absorption power. Whether it is a point-suction wave energy power generation device that captures energy through a linear generator, or a buoyancy pendulum wave energy power generation device that captures energy through a hydraulic turbine and a rotating motor, it can only absorb oscillation energy in a single vertical swing direction or a single swing direction. Therefore, the theoretical energy absorption upper limit is relatively low. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-degree-of-freedom wave energy power generation device, which solves the problem of low upper limit of power capture of single-degree-of-freedom wave power generation devices.

[0007] To achieve the above-mentioned objectives, the present invention provides a multi-degree-of-freedom wave energy power generation device, comprising a buoy body, a weather data module is provided on the top outer surface of the buoy body, a 3-RSR parallel mechanism is installed inside the buoy body, a battery pack is installed on the top of the 3-RSR parallel mechanism, the battery is connected to a rectifier control unit, and a synchronous generator and a torsion spring are installed at the bottom of the 3-RSR parallel mechanism.

[0008] Preferably, the weather data module includes a weather station, which is installed on one side of the upper surface of the antenna bracket, a satellite communication module is installed in the center of the upper surface of the antenna bracket, and the antenna bracket is installed in the center of the top outer surface of the buoy body.

[0009] Preferably, the 3-RSR parallel mechanism includes a moving platform, the battery pack is installed at the center of the top of the moving platform, and the bottom of the moving platform is connected to the fixed platform through a plurality of single-branch chains.

[0010] Preferably, each of the single-branched chains consists of two connecting rods connected by a ball joint.

[0011] Preferably, the moving platform has three degrees of freedom: vertical swing, vertical swing and pitch. Taking the fixed platform as the reference system, the angular velocity and linear velocity of the moving platform satisfy the following constraints: ω , J v Determined by the length of the driving link and the passive link and the instantaneous posture:

[0012]

[0013] The linear velocity of the moving platform is selected to reflect the motion state of the moving platform, where the Jacobian matrix

[0014]

[0015] The mapping relationship between the driving joint angular velocity and the moving platform linear velocity is expressed by J3:

[0016]

[0017] Preferably, the force analysis of the moving platform and the fixed platform is respectively performed as follows:

[0018] The fixed platform and the buoy are regarded as a whole, with a mass of M1 and a moment of inertia of I1. EX , radiation force F R , and hydrostatic restoring force F HS , and the corresponding moment M EX 、M R 、M HS ; The total torque of the three generators' counter-electromagnetic torques ∑τ PTO ;

[0019] The moving platform is not subject to hydrodynamic force, with a mass of M2 and a moment of inertia of I2; it is only subject to the combined torque ∑τ of the counter-electromagnetic torque from the generator. PTO ;

[0020] Under the action of wave force, the fixed platform generates linear velocity v1 and angular velocity ω1 relative to the earth coordinate system;

[0021]

[0022] Under the action of the motor force, the moving platform generates a linear velocity v2 and an angular velocity ω2 relative to the earth coordinate system; according to the principle of virtual work, the mapping of the instantaneous inertial force and inertial moment of the moving platform to the motor's counter-electromagnetic moment can be obtained;

[0023]

[0024] Convert from the fixed platform coordinate system to the geodetic coordinate system; the constraints on the linear velocity and angular velocity of the moving platform itself in the original formula are changed into the constraints on the relative linear velocity and relative angular velocity between the moving and fixed platforms;

[0025] ω1-ω2=J d (v2-v1) (4)

[0026] According to the damping control strategy, the anti-electromagnetic torque changes dynamically within a cycle, and the magnitude of the torque is linearly related to the magnitude of the joint angular velocity. Therefore, the anti-electromagnetic torque can be equivalent to the damping torque, and its equivalent damping coefficient is c. The relationship between the anti-electromagnetic torque and the joint angular velocity of each joint is as follows;

[0027]

[0028] Under a wave period T, the average energy capture power P is the average value of the product of the back electromagnetic torque and the joint angular velocity within the period T;

[0029]

[0030] The buoy is made to have maximum heave or maximum swing to achieve maximum energy capture power, where equations (1)-(5) are constraint conditions and equation (6) is the objective function.

[0031] Preferably, the buoy body is a hollow rotating body structure, the top and the bottom are both truncated cone structures, and the waist is a cylindrical structure.

[0032] Therefore, the present invention adopts a multi-degree-of-freedom wave energy power generation device of the above structure, which has the following

[0033] Beneficial effects:

[0034] (1) The present invention introduces a parallel mechanism as a transmission mechanism, so that the wave energy power generation device can absorb the oscillation energy of the heave motion and the swing motion at the same time, thereby improving the theoretical upper limit of the energy capture power.

[0035] (2) The present invention miniaturizes the wave energy device and places it inside marine equipment such as buoys. Since it can directly power offshore equipment, it not only improves the utilization value of electric energy, but also eliminates the difficulty of electric energy transmission. The wave energy power generation device is completely sealed inside the buoy, which can effectively solve the problems of seawater corrosion and improve reliability and stability.

[0036] (3) The present invention installs a torsion spring at the generator shaft and pre-tightens it to support the gravity of the moving platform, so that the initial position of the mechanism can be maintained in the middle of the internal space of the buoy, thereby obtaining a symmetrical oscillation range. The direct-drive point-suction wave energy power generation device using a linear generator solution requires a relatively high mover kinetic energy to achieve a higher power generation capacity. The huge mover gravity needs to be borne by a high-rigidity compression spring, which occupies a large amount of space and has fatigue problems. The present invention uses a parallel mechanism, and the three branches share the gravity of the moving platform; in addition, under limited space, the torsion spring has a smaller compression ratio than the traditional compression spring, which alleviates the fatigue of the spring to a certain extent and extends its service life.

[0037] (4) The rotating motor used in the present invention is small in size and compact in structure, which greatly saves space inside the buoy. Since the multi-degree-of-freedom oscillation system has different stiffness and mass (moment of inertia) in different directions, the vertical swing motion and the rocking motion of the float have different resonance points (resonance frequencies), which have a wider tuning range than the single-degree-of-freedom resonance. As long as the wave frequency is between the two resonance points, a relatively high energy capture power can be obtained.

[0038] (5) The present invention uses three identical motors to absorb the oscillation energy, and there is no need to design a special energy absorption mechanism or device for each degree of freedom. This reduces manufacturing and maintenance costs, reduces control difficulty, and improves system reliability.

[0039] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a multi-degree-of-freedom wave energy power generation device of the present invention;

[0041] Figure 2 A schematic diagram of a kinematic model of a multi-degree-of-freedom wave energy power generation device according to the present invention;

[0042] Reference numerals

[0043] 1. Buoy body, 2. Battery pack, 3. Moving platform, 4. Connecting rod, 5. Ball joint, 6. Fixed platform, 7. Satellite communication module, 8. Weather station, 9. Antenna bracket, 10. Rectification control unit, 11. Synchronous generator, 12. Torsion spring. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0045] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0046] Example

[0047] like Figure 1As shown, the present invention provides a multi-degree-of-freedom wave energy power generation device, which can provide electrical energy for the buoy itself by absorbing the energy in the three degrees of freedom of wave heave, surge, and pitch motion. The device mainly includes a buoy body 1, a battery pack 2, a moving platform 3, a connecting rod 4, a ball joint 5, a fixed platform 6, a synchronous generator 11 and a torsion spring 12. The battery pack 2 is fixedly connected to the moving platform 3 as an oscillation unit, and the fixed platform 6 is fixedly connected to the bottom surface of the buoy as another oscillation unit. A torsion spring 12 is installed on the rotating pair between the generator mover and the connecting rod 4. Under the action of the generator's anti-electromagnetic torque, part of the wave force on the fixed platform can be transmitted to the moving platform 3 and generate mutual oscillation.

[0048] The buoy body 1 is a hollow rotating body structure, with the top and bottom being truncated cone structures and the waist being a cylindrical structure. An antenna bracket 9 is provided on the top, on which a satellite communication module 7 and a weather station 8 are mounted for collecting and transmitting weather data. The bottom is provided with evenly distributed saddle pin hanging ears, on which an anchor chain is fixed.

[0049] Under the action of wave forces and wave moments in multiple directions on the sea surface, the buoy body 1 will produce heave and sway motions with multiple degrees of freedom. The heavy objects (moving platform 3 and battery pack 2) inside the buoy are not affected by wave forces. Therefore, the relative position of the top platform 6 and the moving platform 3 will change with the change of wave forces. Since the moving platform 3 has a certain inertia, the oscillation of the moving platform 3 will follow and lag behind the oscillation of the buoy body 1 to a certain extent. The two will produce relative heave displacement and relative sway angular displacement. Through the 3-RSR transmission mechanism, the relative motion is mapped to the rotating pair where the synchronous generator 11 is located, driving the synchronous generator 11 on the fixed platform 3 to rotate. The torsion spring 12 on the generator needs to be pre-tightened to bear the entire gravity of the moving platform 3, thereby reducing the load of the generator. At the same time, it can also store part of the energy during the oscillation process and reduce the impact on the generator during the oscillation process. Under the action of wave forces, the direction of the synchronous generator 11 will change frequently with the wave force cycle, and the alternating current generated by the synchronous generator 11 cannot directly charge the battery 2, so a rectifier control unit 10 is also required. In addition, by controlling the size of the current in the circuit, the size of the generator's anti-electromagnetic torque can be controlled to a certain extent, thereby intervening in the oscillation process, amplitude and rotation angle, and adapting to different sea conditions to achieve maximum absorbed power. In addition, by setting a larger anti-electromagnetic torque, the mover can be limited or even locked, thereby protecting the wave energy generation device in extremely harsh sea conditions and preventing it from being damaged due to excessive oscillation of the moving platform beyond the working space.

[0050] The 3-RSR parallel mechanism used in this device is composed of a moving platform 3, a connecting rod 4, a ball joint 5 and a fixed platform 6. Each single branch chain is connected by two connecting rods 4 through a ball joint 5. The connecting rod 4 is connected to the moving platform 3 and the fixed platform 6 through a rolling bearing type rotating pair. The mechanism uses exactly the same three branches in parallel. The moving platform 3 has three degrees of freedom: vertical swing, vertical swing and pitch. Through the Jacobian matrix, the motion state of the moving platform, including displacement and angular displacement, as well as inertial force and inertial moment, is mapped to the engine rotor of the fixed platform, which is simplified to the dynamic equations of torque and angle on the generator rotor. Based on these dynamic equations, the power generation process can be controlled.

[0051] like Figure 2 As shown, the dynamics and control principles of the present invention are as follows:

[0052] In order to effectively control the multi-degree-of-freedom wave energy generation device, it is necessary to establish a dynamic model of the floating body oscillation.

[0053] First, the kinematics of the mechanism are analyzed. Taking the fixed platform as the reference system, the angular velocity and linear velocity of the moving platform satisfy the following constraints. ω , J v Determined by the length of the driving link and the passive link and the instantaneous attitude.

[0054]

[0055] The linear velocity of the moving platform is selected to reflect the motion state of the moving platform. The Jacobian matrix

[0056]

[0057] Generally, the full Jacobian matrix J is used A To reflect the motion state of the dynamic platform to the angular velocity of the driving joint 's mapping.

[0058]

[0059] For a 3-RSR parallel mechanism with three driven joints, is a 6×3 matrix, take The upper part of the 3×3 block matrix is ​​recorded as J3, and the above formula can be rearranged as follows:

[0060]

[0061] The dynamics of the mechanism requires separate force analysis of the moving platform and the fixed platform.

[0062] The fixed platform and the buoy are considered as a whole, with a mass of M1 and a moment of inertia of I1. EX , radiation force F R , and hydrostatic restoring force F HS , and the corresponding moment M EX 、M R 、M HS The total torque of the three generators' counter-electromagnetic torques is ∑τ PTO .

[0063] The moving platform is not subject to hydrodynamic force, with a mass of M2 and a moment of inertia of I2. It is only subject to the combined torque ∑τ of the counter-electromagnetic torque from the generator PTO .

[0064] Under the action of wave force, the fixed platform generates linear velocity v1 and angular velocity ω1 relative to the earth coordinate system.

[0065]

[0066] Under the action of the motor force, the moving platform generates a linear velocity v2 and an angular velocity ω2 relative to the earth coordinate system. According to the principle of virtual work, the mapping of the instantaneous inertial force and inertial moment of the moving platform to the motor's counter-electromagnetic moment can be obtained.

[0067]

[0068] From the fixed platform coordinate system to the earth coordinate system, the constraints of the linear velocity and angular velocity of the moving platform itself in the original formula are transformed into the constraints of the relative linear velocity and relative angular velocity between the moving and fixed platforms.

[0069] ω1-ω2=J d (v2-v1) (4)

[0070] It can be seen from the formula that the wave excitation torque directly causes the target body to sway, thereby driving the synchronous generator rotor. The wave excitation force first causes the target body and the weight to produce relative displacement, which is mapped into joint angular displacement through the parallel mechanism. Both the excitation force and the excitation torque can contribute to the relative motion of the synchronous generator rotor and stator, thereby achieving the simultaneous absorption of energy in multiple oscillation directions.

[0071] According to the damping control strategy, the anti-electromagnetic torque changes dynamically within a cycle, and the magnitude of the torque is linearly related to the magnitude of the joint angular velocity. Therefore, the anti-electromagnetic torque can be equivalent to the damping torque, and its equivalent damping coefficient is c. The relationship between the anti-electromagnetic torque and the joint angular velocity of each joint is as follows.

[0072]

[0073] Under a wave period T, the average energy capture power P is the average value of the product of the back electromagnetic torque and the joint angular velocity within the period T.

[0074]

[0075] Make the buoy undergo maximum heave or maximum swing to achieve maximum energy capture power.

[0076] According to the above dynamic equations, the generator anti-electromagnetic torque directly affects the swing motion, and then indirectly affects the heave motion through the Jacobian matrix conversion of the parallel mechanism. The wave excitation torque can be regarded as a sinusoidal input. The hydrostatic restoring torque and radiation torque are linearly related to the angular displacement and angular velocity, respectively. Under the combined action of the wave torque and the anti-electromagnetic torque, the swing of the buoy presents a forced vibration state.

[0077] There are implicit function relationships and nonlinear terms in the dynamic equations of the multi-degree-of-freedom wave energy power generation device described in the present invention. For example, the inertia moment contains the square term of the angular velocity, and there are dynamically changing Jacobian matrices J3 and J d . In addition, the shape of the buoy is different from the common buoys used for point-suction wave energy generation, and does not have the same cross-sectional area at different heights. Therefore, in the heave range and swing range, the relationship between the hydrostatic restoring force and the radiation damping force with displacement is not linear. It is difficult to use mathematical models such as state space to solve the analytical solution of the speed resonance condition and the optimal motor torque size. For this, the optimization design method can be used. Equations (1)-(5) are constraints, and Equation (6) is the objective function. The maximum average energy capture power and the generator equivalent damping coefficient c required to achieve the maximum power are calculated.

[0078] Therefore, the present invention adopts the above-mentioned multi-degree-of-freedom wave energy power generation device, and by introducing a parallel mechanism as a transmission mechanism, the wave energy power generation device can absorb the oscillation energy in the heave direction and the swing direction at the same time, thereby improving the theoretical upper limit of energy capture power. The wave energy device is miniaturized and placed in marine equipment such as buoys. Since it can directly power offshore equipment, it not only improves the utilization value of electric energy, but also eliminates the difficulty of electric energy transmission. The wave energy power generation device is completely sealed inside the buoy, which can effectively solve problems such as seawater corrosion and improve reliability and stability. Compared with linear generators, which also occupy a large amount of vertical travel and rely on long guide rails to realize the process of rotor acceleration, the rotary motor used in the present invention is small in size and compact in structure, which greatly saves space inside the buoy. Since the multi-degree-of-freedom oscillation system has different stiffness and mass (moment of inertia) in different directions, the heave motion and swing motion of the floating body have different resonance points (resonance frequencies), which have a wider tuning range than the single-degree-of-freedom resonance. As long as the wave frequency is between the two resonance points, a relatively high energy capture power can be obtained.

[0079] A torsion spring is installed at the generator shaft and pre-tightened to support the gravity of the moving platform, so that the initial position of the mechanism can be maintained in the middle of the internal space of the buoy, thereby obtaining a symmetrical oscillation range. Since the present invention uses a parallel mechanism, the three branch chains share the gravity of the moving platform and relieve the fatigue of the torsion spring.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A multi-degree-of-freedom wave energy power generation device, characterized in that: It comprises a buoy body, a weather data module is arranged on the top outer surface of the buoy body, a 3-RSR parallel mechanism is installed inside the buoy body, a battery pack is installed on the top of the 3-RSR parallel mechanism, the battery is connected to a rectifier control unit, a synchronous generator and a torsion spring are installed at the bottom of the 3-RSR parallel mechanism, the weather data module comprises a weather station, the weather station is installed on one side of the upper surface of the antenna bracket, a satellite communication module is installed at the center of the upper surface of the antenna bracket, and the antenna bracket is installed at the center of the top outer surface of the buoy body; The battery pack is installed at the center of the top of the moving platform of the 3-RSR parallel mechanism, and the bottom of the moving platform is connected to the fixed platform through a plurality of single-branch chains; The battery pack is fixedly connected to the moving platform as an oscillation unit, and the fixed platform is fixedly connected to the bottom surface of the buoy as another oscillation unit; a torsion spring is installed on the rotating pair between the generator mover and the connecting rod, and under the action of the generator torque, part of the wave force on the fixed platform can be transmitted to the moving platform and generate mutual oscillation; Through the 3-RSR transmission mechanism, the relative motion is mapped to the rotating pair where the synchronous generator is located, driving the synchronous generator on the fixed platform to rotate.

2. A multi-degree-of-freedom wave energy power generation device according to claim 1, characterized in that: Each of the single-branch chains is composed of two connecting rods connected by a ball joint.

3. A multi-degree-of-freedom wave energy power generation device according to claim 1, characterized in that: The moving platform has three degrees of freedom: vertical swing, vertical swing and pitch. Taking the fixed platform as the reference system, the angular velocity and linear velocity of the moving platform satisfy the following constraints: , Determined by the length of the driving link and the passive link and the instantaneous posture: ； The linear velocity of the moving platform is selected to reflect the motion state of the moving platform, where the Jacobian matrix : ； 。 4. A multi-degree-of-freedom wave energy power generation device according to claim 1, characterized in that: The force analysis of the moving platform and the fixed platform is as follows: Considering the fixed platform and the buoy as a whole, the mass is , the moment of inertia is ; The wave excitation force , Radiation , and hydrostatic resilience , and the corresponding torque ; The combined torque of the three generator back electromagnetic torques ; The dynamic platform is not subject to water force and its mass is , the moment of inertia is ; The only torque is the counter-electromagnetic torque from the generator. ; Under the action of wave force, the fixed platform generates a linear velocity relative to the earth coordinate system. , angular velocity ; （1） （2） Under the action of the motor force, the moving platform generates a linear velocity relative to the earth coordinate system. , angular velocity ; According to the principle of virtual work, the mapping of the instantaneous inertial force and inertial moment of the moving platform to the counter-electromagnetic moment of the motor can be obtained; （3） Convert from the fixed platform coordinate system to the geodetic coordinate system; the constraints on the linear velocity and angular velocity of the moving platform itself in the original formula are changed into the constraints on the relative linear velocity and relative angular velocity between the moving and fixed platforms; （4） According to the damping control strategy, the anti-electromagnetic torque changes dynamically within a cycle, and the magnitude of the torque is linearly related to the magnitude of the joint angular velocity. The anti-electromagnetic torque can be equivalent to the damping torque, and its equivalent damping coefficient is , the relationship between the anti-electromagnetic torque of each joint and the joint angular velocity is as follows; （5） In a wave cycle The average energy capture power The product of the back electromagnetic torque and the joint angular velocity in the period The average value within （6） The buoy is made to have maximum heave or maximum swing to achieve maximum energy capture power, where equations (1)-(5) are constraint conditions and equation (6) is the objective function.

5. A multi-degree-of-freedom wave energy power generation device according to claim 1, characterized in that: The buoy body is a hollow rotating body structure, the top and the bottom are both truncated cone structures, and the waist is a cylindrical structure.

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