Adjustable air turbine flow wave energy generation buoy and control method thereof

Abstract

The application discloses a wave energy generating buoy capable of adjusting air turbine flow and a control method thereof. The buoy comprises an air turbine, a cam rotary disc, a driving gear, a driven gear, a servo motor, a driven shaft and a rigid buoy. An air chamber and a cavity are arranged in the rigid buoy, and an air pressure sensor and a liquid level sensor are arranged in the air chamber. The cam rotary disc is rotatably arranged between an air outlet and the air turbine, and is driven to rotate by the servo motor and a gear pair, so that the effective flow area of the air outlet is steplessly adjusted. The control method is based on the real-time collected air chamber pressure and liquid level change rate, calculates the optimal air chamber pressure corresponding to the optimal efficiency of the turbine, establishes the mapping relationship between the flow area and the pressure, and corrects the cam rotation angle in real time through PID closed loop control, so that the air chamber pressure dynamically tracks the optimal value. The application can optimize the wave energy capturing efficiency and the power generation power, widen the wave working condition adaptation range, and effectively prevent the turbine from being damaged by high-pressure air flow impact.

Description

Technical Field

[0001] This invention relates to the field of marine energy power generation technology, specifically to the field of wave energy conversion device technology, and particularly to a wave energy power generation buoy with adjustable air turbine flow rate and its control method. Background Technology

[0002] This invention relates to the field of wave energy power generation buoys, and particularly to a wave energy power generation buoy with adjustable air turbine flow rate and its control method.

[0003] Wave energy, as a clean and renewable marine energy source, has significant advantages such as huge reserves, wide distribution, high energy density, and stability superior to wind and solar energy. Its power generation process does not produce greenhouse gases or pollutants, making it environmentally friendly. At the same time, wave energy resources are mostly concentrated in densely populated coastal areas with high energy demand, making it easy to develop and utilize them nearby. It can effectively supplement traditional energy sources and help transform the energy structure. Furthermore, wave energy power generation devices can be flexibly adapted to different sea conditions, and have broad application prospects in scenarios such as island power supply and marine infrastructure power supply.

[0004] Currently, wave energy buoys can be classified into four types based on their energy capture principles: oscillating water column buoys, oscillating float buoys, wave-overtaking buoys, and point-absorption buoys. Compared to other wave energy buoys, oscillating water column buoys have the core advantages of having no moving parts in contact with seawater, stronger structural corrosion resistance and resistance to marine organism adhesion, lower operation and maintenance costs, and superior stability and reliability in complex sea conditions. Taking a center-tube wave energy buoy as an example, the buoy oscillates or pitches with the waves, causing the water column inside the center tube to oscillate back and forth. This compresses the air in the air chamber inside the tube, forming a directional airflow that drives the air turbine to rotate, thereby driving the generator to generate electricity, achieving a three-stage conversion from wave energy to electrical energy.

[0005] To improve the efficiency of wave energy generation buoys, the industry has conducted extensive research. For example, patent CN120039354B discloses a wave energy generation buoy with a variable float diameter and its control method, which adjusts the hydrodynamic characteristics of the buoy by changing the float diameter; patent CN110406635B proposes a multi-stage power supply buoy with a central tube; and patent CN117052588B proposes an oscillating water column type wave energy generation device. These technologies have contributed to improving power output and management, but when dealing with the randomness, volatility, and complex sea conditions of wave energy, it is still difficult to limit the high pressure in the air chamber, protect the turbine and generator set, and achieve safe braking under extreme sea conditions. Problems such as low energy capture efficiency, insufficient power generation stability, and limited system protection capabilities still exist.

[0006] Furthermore, there is an invention patent with authorization announcement number CN118494679B, entitled "A Wave Energy Generating Buoy with Variable Heave Plate Depth and Method." This patent discloses a scheme to change the hydrodynamic characteristics of a buoy by adjusting the depth of the heave plate. Its core lies in using a lockable telescopic device and a push rod to dynamically adjust the distance between the heave plate and the float based on wave parameters, thereby changing the buoy's natural frequency and added mass, allowing the buoy to resonate with the waves and thus improve wave energy capture efficiency. However, this scheme focuses on adjustment from the wave incident end (hydrodynamic level), employing a passive adaptation approach of adjusting the buoy's own frequency response, without addressing the active control of aerodynamic parameters during energy conversion. Under complex nonlinear wave conditions, its adjustment mechanism is constantly immersed in seawater, facing severe challenges such as sealing, corrosion, and marine organism attachment, posing challenges to the long-term reliability and maintenance costs of the device. Simultaneously, this scheme cannot directly solve the problems of air chamber pressure surge and turbine overload protection unique to oscillating water column buoys.

[0007] Therefore, a wave energy generation buoy with adjustable air turbine flow rate is needed to optimize wave energy capture efficiency and power generation, broaden the adaptability range of wave operating conditions, and effectively prevent the turbine from being damaged by the impact of high-pressure airflow. Summary of the Invention

[0008] The purpose of this invention is to provide a wave energy power generation buoy with adjustable air turbine flow rate and its control method. By using a cam turntable mechanism and a closed-loop control strategy to dynamically adjust the air turbine flow rate in real time, the air chamber pressure adaptively tracks the optimal value. Compared with the prior art, this invention not only significantly improves wave energy capture efficiency and power generation, and broadens the adaptability range for wave operating conditions, but also takes into account the turbine high-pressure impact protection and long-term high reliability of the system by taking advantage of the rapid response adjustment in the air medium and the natural resistance to seawater corrosion.

[0009] The technical solution adopted in this invention is as follows: A wave energy generating buoy with adjustable air turbine flow rate includes an air turbine, a cam turntable, a drive gear, a driven gear, a servo motor, a driven shaft, and a rigid buoy. The rigid pontoon has an air chamber and a cavity inside, with a water inlet at the bottom, an air outlet at the top, and a turbine support at the top. The air turbine is fixedly installed via the turbine bracket and is coaxial with the air outlet; The cam turntable is rotatably disposed between the air outlet and the air turbine, and a gap is left between the cam turntable and both the air outlet and the air turbine, so as to change the effective flow area of ​​the air outlet by rotating. The driven gear and the cam turntable are coaxially and fixedly connected via the driven shaft; the driving gear is fixedly mounted on the output shaft of the servo motor and meshes with the driven gear for transmission; the servo motor is fixed to the rigid float. A pressure sensor and a liquid level sensor are installed in the air chamber; The buoy also includes a heave plate and a mooring ring. The rigid buoy is fixedly connected to the heave plate by multiple connecting rods, and the mooring ring is fixed to the center of the heave plate.

[0010] Preferably, the cam turntable is a disc with a fan-shaped notch, and the flow area is adjusted by rotating it to change the degree of overlap between the notch and the air outlet.

[0011] Preferably, there are four connecting rods, evenly distributed along the circumference.

[0012] Preferably, the driving gear and the driven gear are spur gears.

[0013] Preferably, the system also includes a controller, which is electrically connected to the pressure sensor, the liquid level sensor, and the servo motor, respectively, for receiving pressure and liquid level signals and outputting control signals to drive the servo motor according to a preset control strategy.

[0014] A control method for a wave energy generating buoy with adjustable air turbine flow rate, wherein the wave energy generating buoy is as described above, includes the following steps: Step S1: Collect real-time air pressure in the air chamber using a barometer. The water level in the gas chamber is collected using a liquid level sensor. ; Step S2: Determine the current working stage of the buoy based on the water level change. When the water level rises, it is determined to be the air venting stage; when the water level falls, it is determined to be the air intake stage. Step S3: Calculate the rate of change of liquid level in For water level, The optimal flow rate corresponding to the best efficiency of the air turbine is calculated based on the liquid level change rate over time. and optimal air chamber pressure Wherein, the optimal flow rate The optimal pressure The flow correction factor is determined based on the turbine surge boundary and efficiency peak fitting. The cross-sectional area of ​​the air chamber is... This is the air pressure correction factor; Step S4: Establish the optimal circulation area With optimal pressure The functional relationship, where For flow coefficient, Atmospheric pressure. for Step S5: Establish the rotation angle of the cam turntable With circulation area The mapping relationship is used to obtain the corresponding optimal pressure. Theoretical perspective The mapping relationship is obtained through pre-calibration, and the corresponding angle when the cam is fully closed is... The corresponding angle when fully open is The theoretical perspective Through function Sure; Step S6: Calculate the deviation between real-time pressure and optimal pressure. ; Step S7: Use a PID control algorithm based on the deviation. Calculate the angle fine adjustment amount ; Step S8: Control the servo motor to drive the cam turntable to rotate the total angle. This allows for the adjustment of circulation area; Step S9: Determine real-time air pressure Is it within the optimal pressure range? If the pressure is within the optimal range, the current cam disc opening is maintained and minor adjustments are made; otherwise, the process returns to step S2 to continue closed-loop control. This is the allowable deviation threshold.

[0015] Preferably, the flow correction coefficient in step S3 The pressure correction coefficient is obtained by fitting the surge boundary and efficiency peak of the air turbine. The matching characteristics between the air chamber and the turbine were obtained through experimental calibration.

[0016] Preferably, the flow coefficient mentioned in step S4 The geometry of the cam turntable and the structure of the air outlet are determined by fluid simulation or calibration tests.

[0017] Preferably, the mapping relationship described in step S5 is obtained through experimental calibration, wherein the angle corresponding to the cam being fully closed is... Corresponding angle when fully open It is limited by the mechanical structure of the cam turntable.

[0018] Preferably, the allowable deviation threshold mentioned in step S9 Set to current optimal pressure 3% .

[0019] The beneficial effects of this invention are as follows: This invention alters the airflow area by adjusting a cam disc at the air outlet. The cam disc is positioned in the air medium, not seawater, resulting in lightweight and low-resistance moving parts. The servo motor can complete angle adjustment commands within milliseconds, providing a response speed far faster than underwater mechanical adjustment methods. This speed advantage allows the buoy to dynamically adjust in real-time to follow the instantaneous changes of individual waves, rather than only responding to long-period average wave conditions. This enables efficient turbine operation within each wave cycle, significantly improving wave energy capture efficiency—something unattainable with existing technologies.

[0020] In this invention, all adjustment mechanisms, including the cam turntable, drive gear, driven gear, driven shaft, and servo motor, are located in the air environment at the top of the rigid buoy, completely avoiding contact with seawater. This fundamentally prevents seawater corrosion and marine organism adhesion problems, and eliminates the need for complex dynamic sealing structures. This structural layout brings unexpectedly high reliability, enabling the buoy of this invention to operate stably for extended periods in unattended open-ocean environments, significantly reducing maintenance frequency and costs.

[0021] The cam turntable mechanism of this invention possesses safety protection functions at the control strategy level: when an abnormal surge in air chamber pressure is detected, exceeding a preset safety threshold, the controller can instantly drive the cam turntable to the fully open state, rapidly releasing the high-pressure airflow to prevent the turbine from being damaged by impact; or, in the event of emergency braking, the cam turntable can be driven to the fully closed state, cutting off the airflow to achieve pneumatic braking of the turbine. This ability to achieve rapid and safe cut-off at the end of the energy conversion path is not available in existing hydrodynamic control schemes, providing a final safety line for the system and unexpectedly improving the equipment's survivability under extreme sea conditions.

[0022] The control strategy of this invention directly uses the chamber pressure and liquid level change rate as feedback signals, and takes the chamber pressure corresponding to the turbine's optimal efficiency as the control target, resulting in a simple and clear control loop. Since the chamber pressure and liquid level change rate are themselves direct products of wave excitation and buoy response, they naturally encompass all hydrodynamic and aerodynamic coupling effects. Therefore, the controller does not need to establish a complex wave-buoy coupling model; high-efficiency closed-loop control can be achieved using only two directly measurable physical quantities. This results in a more robust control strategy and better adaptability to different sea areas and wave patterns—a technological advantage that is difficult to foresee in existing technologies. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a wave energy generating buoy with adjustable air turbine flow rate according to the present invention. Figure 2This is a schematic diagram of the structure for adjusting the air turbine flow rate according to the present invention; Figure 3 This is a cross-sectional structural diagram of the present invention; Figure 4 This is a schematic diagram of the flow regulation in the fully closed, partially open / partially closed, and fully open states of the present invention; Figure 5 This is a schematic diagram of the process of the present invention; The components are: 1. Air turbine, 2. Cam turntable, 3. Drive gear, 4. Driven gear, 5. Servo motor, 6. Driven shaft, 7. Rigid float, 7-1. Turbine support, 7-2. Air chamber, 7-3. Cavity, 7-4. Water inlet, 7-5. Air outlet, 8. Connecting rod, 9. Heave plate, 10. Mooring ring, 11. Air pressure sensor, 12. Liquid level sensor. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] This invention provides a wave energy power generation buoy with adjustable air turbine flow rate and its control method. The core idea is to set an adjustable cam turntable mechanism between the air turbine and the air outlet of the air chamber. By monitoring the changes in air pressure and liquid level in the air chamber in real time, and combining the turbine characteristics, the target air pressure that optimizes the turbine efficiency under the current sea state is calculated. The opening of the cam turntable is dynamically adjusted using closed-loop control to change the effective flow area of ​​the air outlet, so that the air chamber pressure adaptively tracks the optimal pressure. This not only significantly improves the wave energy capture efficiency and power generation, and broadens the applicable wave operating conditions, but also effectively limits the impact of high-pressure airflow on the turbine under strong swell conditions, thus achieving equipment self-protection.

[0026] See Figures 1 to 5 An exemplary embodiment of the wave energy generating buoy with adjustable air turbine flow rate of the present invention includes: an air turbine 1, a cam turntable 2, a drive gear 3, a driven gear 4, a servo motor 5, a driven shaft 6, a rigid float 7, a connecting rod 8, a heave plate 9, a mooring ring 10, a pressure sensor 11, and a liquid level sensor 12.

[0027] The rigid buoy 7 is the base of the entire device. It contains an air chamber 7-2 and a cavity 7-3, with a water inlet 7-4 at the bottom, an air outlet 7-5 at the top, and a turbine support 7-1 at the top. The air chamber 7-2 is used to realize the first stage of energy conversion from wave energy to air pressure energy; the cavity 7-3 is used to provide sufficient buoyancy for the buoy to ensure its floating state on the sea surface; the water inlet 7-4 allows seawater to enter the lower part of the air chamber, thereby forming an oscillating water column in the air chamber when the sea surface is fluctuating; the air outlet 7-5 guides the reciprocating airflow generated by the oscillating water column to the air turbine 1, driving the turbine to rotate.

[0028] The air turbine 1 is fixedly mounted on the turbine support 7-1, and its installation position should ensure that it is coaxial with the air outlet 7-5, so that the airflow from the air outlet 7-5 can act positively on the turbine blades, reducing flow losses. The air turbine 1 can be a bidirectional impulse turbine or a Wells turbine to adapt to the characteristics of the reciprocating airflow in the air chamber, so as to output unidirectional rotational motion in both exhaust and intake stages, or output unidirectional rotation through a rectifier mechanism, thereby driving the generator to generate electricity.

[0029] A cam disk 2 is rotatably mounted between the air outlet 7-5 and the air turbine 1. Appropriate gaps are maintained between the cam disk 2 and both the air outlet 7-5 and the air turbine 1 to prevent mechanical interference and wear during rotation, while ensuring effective airflow throttling. The cam disk 2 is a disc with a fan-shaped notch, and its effective flow area is adjusted by changing the overlap between the notch and the air outlet 7-5 through rotation. Figure 4 The positional relationships of the cam turntable 2 in three states—fully closed, partially open / half closed, and fully open—are shown respectively. When the fan-shaped notch is completely offset from the air outlet, the flow area is at its minimum, close to the closed state; when the fan-shaped notch is completely aligned with the air outlet, the flow area is at its maximum, which is the fully open state. By steplessly adjusting the notch alignment, the flow area can be continuously changed, thereby regulating the gas flow rate through the air turbine.

[0030] The rotation of the cam turntable 2 is driven by a gear transmission mechanism and a servo motor 5. Specifically, the driven gear 4 is coaxially and fixedly connected to the cam turntable 2 via a driven shaft 6, and the two can rotate synchronously. The driving gear 3 is fixedly mounted on the output shaft of the servo motor 5 and meshes with the driven gear 4 for transmission. When the servo motor 5 rotates, it drives the driven gear 4 and the driven shaft 6 through the driving gear 3, thereby causing the cam turntable 2 to rotate. In this embodiment, both the driving gear 3 and the driven gear 4 are cylindrical spur gears, which have the advantages of simple structure, reliable transmission, and easy processing. The servo motor 5 is firmly fixed to the top of the rigid float 7 at an appropriate position by bolts, and the servo motor 5 adopts a control method with position feedback, which can accurately control the rotation angle of the cam turntable 2, thereby achieving high-precision flow area adjustment.

[0031] Inside the air chamber 7-2 of the rigid float 7, a pressure sensor 11 and a level sensor 12 are installed. The pressure sensor 11, denoted by P and measured in Pascals (Pa), is used to collect the real-time air pressure within the chamber. A piezoresistive miniature pressure transmitter can be used, featuring fast response, high accuracy, and corrosion resistance. The level sensor 12, denoted by h and measured in meters (m), is used to collect the real-time water level within the chamber. A non-contact ultrasonic level gauge or radar level gauge can be used to avoid direct contact with seawater and improve reliability. Alternatively, an immersion-type pressure sensor can be used to indirectly measure the level. The signals from both sensors are transmitted via cable to the control system for processing and calculation.

[0032] To improve the heave motion and attitude stability of the buoy at sea, this invention also includes a heave plate 9 and a mooring ring 10. The rigid buoy 7 is fixedly connected to the heave plate 9 via multiple connecting rods 8. Figure 1 and Figure 3 In the specific structure shown, there are four connecting rods 8, evenly distributed along the circumference to ensure uniform force distribution. The heave plate 9 is a horizontally arranged flat plate structure, preferably a circular or polygonal steel plate, which can increase the added mass and hydrodynamic damping during vertical movement, reduce the heave response amplitude of the buoy, and improve wave energy capture stability and platform stability. The mooring ring 10 is fixed at the center of the heave plate 9 and is used to connect the mooring cable to anchor the entire buoy system to the designated position on the seabed.

[0033] The wave energy generating buoy of this invention also includes a controller, which can be installed in a waterproof electrical compartment inside the rigid buoy 7. The controller is electrically connected to a pressure sensor 11, a liquid level sensor 12, and a servo motor 5. The controller receives pressure and liquid level signals, performs calculations according to a built-in preset control strategy, and outputs a control signal to drive the servo motor 5 to perform real-time adjustment of the angle of the cam turntable 2. The controller body can be an industrial-grade microcontroller or a programmable logic controller (PLC), equipped with an analog signal acquisition module, a digital signal output module, and a PWM or position control interface to realize data reading from the sensors and command transmission to the servo motor.

[0034] During operation, the buoy oscillates with the waves, and the water column in air chamber 7-2 oscillates reciprocally under wave excitation. When the wave crest arrives and the buoy moves upward, the water column rises relative to the air chamber, compressing the upper air volume. At this time, the air pressure increases, generating an outward airflow. When the wave trough arrives and the buoy moves downward, the water column descends, the air chamber volume increases, the air pressure decreases, and outside air is drawn into the air chamber. This alternating exhalation and inhalation process forms a reciprocating airflow, driving the air turbine 1 to rotate, which in turn drives the generator to convert rotational mechanical energy into electrical energy. The air chamber pressure directly affects the efficiency and output power of the air turbine. If the air chamber pressure is too high, the excessive flow velocity inside the turbine may cause surge and blade impact damage; if the pressure is too low, wave energy cannot be fully utilized. Therefore, by adjusting the air outlet flow area in real time to regulate the air chamber pressure, the turbine can always operate in the high-efficiency range and ensure equipment safety.

[0035] The following is combined Figure 5 The flowchart illustrates in detail the control method for adjusting the air turbine flow rate using a wave energy buoy in this embodiment. This method inherits and includes the features of the aforementioned device, and the control steps are as follows: Step S1: Collect real-time air pressure in the air chamber using air pressure sensor 11. The real-time water level in the air chamber is collected using liquid level sensor 12. The controller synchronously acquires and digitally filters the two signals at a certain sampling frequency (e.g., 10 Hz) to obtain accurate and real-time air chamber state parameters.

[0036] Step S2: Determine the current operating stage of the buoy based on water level changes. The controller monitors the water level at continuous intervals. The system performs differential calculations or uses an internal timer to calculate the liquid level change trend. When a rise in water level is detected, it is determined that air chamber 7-2 is in the exhaust phase. At this time, the air chamber pressure is higher than the external atmospheric pressure, and airflow drives the turbine. When a drop in water level is detected, it is determined that air chamber 7-2 is in the intake phase. At this time, the air chamber pressure is lower than the external atmospheric pressure, and external air flows in. This judgment can be used for subsequent pressure correction or turbine operating mode selection, but this closed-loop control strategy is applicable to both the intake and exhaust phases, without the need for forced switching of control modes.

[0037] Step S3: Calculate the rate of change of liquid level This refers to the rate of change of the liquid level, which directly reflects the intensity and frequency of the current wave. Based on the fundamental principle of wave energy conversion, for air turbine 1 to achieve optimal efficiency, air chamber 7-2 needs to operate at a specific optimal pressure, which corresponds to a certain flow rate requirement. Therefore, the controller first calculates the optimal flow rate corresponding to the optimal efficiency of the air turbine based on the rate of change of the liquid level. and optimal air chamber pressure Specifically, the optimal flow rate is determined by the following formula. ;in, Let be the cross-sectional area of ​​the air chamber, which is a fixed design parameter; This is the flow rate correction factor, which is mainly determined through wind tunnel experiments or computational fluid dynamics simulation fitting based on the surge boundary and efficiency peak of the air turbine. It reflects the true efficiency characteristics of the turbine under different flow rates. The optimal pressure is calculated by the following formula: ;in, This is a pressure correction coefficient, established through experimental calibration to determine the relationship between chamber pressure and turbine flow rate, taking into account the compressibility of the chamber and the flow resistance of the pipeline. Through this step, the controller can dynamically calculate the optimal operating pressure target value based on instantaneous wave conditions.

[0038] Step S4: Establish the optimal circulation area With optimal pressure The functional relationship is as follows: For a given air outlet structure and cam type, the size of the flow area determines the gas flow rate that can pass through under a specific pressure difference. According to fluid mechanics principles, under the assumption of subsonic flow, the mass flow rate through a variable orifice is related to the effective flow area, the upstream and downstream pressure difference, and the gas density. This scheme uses the following relationship to calculate the optimal flow area: In the formula, The flow coefficient depends on the geometry of the cam turntable 2, the chamfer of the air outlet 7-5, and their relative positions. It can be obtained through fluid simulation or calibration tests. Atmospheric pressure; The air density can be taken as a standard value under current meteorological conditions or measured by a sensor. This step achieves an analytical conversion from the desired pressure to the required flow area.

[0039] Step S5: Establish the rotation angle of cam turntable 2 With circulation area The mapping relationship is obtained, and the corresponding optimal pressure is obtained. Theoretical perspective Since the opening degree of the cam turntable 2 and the effective flow area usually exhibit a non-linear relationship, it needs to be pre-calibrated experimentally during the design phase. The specific operation is as follows: the cam turntable 2 is mounted on a test bench, and its rotation angle is gradually changed using the servo motor 5. Simultaneously, the corresponding flow area is recorded using a flow meter or equivalent area measuring device. This yields discrete data pairs, and a mapping function is established. The calibration defines the rotation angle as follows: when the cam is fully closed. At this point, the fan-shaped notch is completely offset from the air outlet, and the flow area is approximately zero; when the cam is fully open, the rotation angle is... At this point, the fan-shaped notch perfectly coincides with the air outlet, and the flow area is at its geometric maximum. Based on this mapping, the value calculated in step S4... Input function This will allow the pressure in the air chamber to tend towards Required theoretical cam angle During control execution, the controller retrieves a lookup table or calculates a fitting formula based on the current operating state to provide... .

[0040] Step S6: Calculate the deviation between real-time pressure and optimal pressure. The magnitude and sign of this deviation reflect the degree to which the current actual state deviates from the ideal state, and it is the core error signal of closed-loop control. Step S7: Use a PID control algorithm based on the deviation. Calculate the angle fine adjustment amount The PID controller takes the following form: ;in, , These are the proportional, integral, and derivative gain coefficients, respectively. These three coefficients need to be tuned in the field or through simulation based on the system's dynamic characteristics to ensure that the control is both fast and stable, without causing excessive overshoot or oscillation in the servo motor and mechanical transmission components. By introducing the integral term, steady-state error can be eliminated, allowing the actual pressure to more accurately follow changes in pressure. The differential term helps to suppress instantaneous pressure spikes caused by sudden wave changes.

[0041] Step S8: Control the servo motor 5 to drive the cam turntable 2 to rotate the total angle. This allows for the adjustment of the flow area. In other words, the final angle reached by the cam turntable is equal to the theoretically optimal angle calculated for the current sea state plus the closed-loop fine-tuning amount caused by pressure deviation. After receiving the position command from the controller, the servo motor 5 uses its built-in drive to rotate, which in turn drives the cam turntable 2 for precise positioning via the driving gear 3 and the driven gear 4. This process can be performed after each sensor sampling, achieving continuous online adjustment.

[0042] Step S9: Determine real-time air pressure Is it within the optimal pressure range? Due to wave irregularities and model simplification, actual pressure is rarely exactly equal to... Therefore, an allowable deviation threshold is set. .if If the current air chamber pressure is considered to be near the optimal pressure, the controller can maintain the current opening of the cam turntable 2 without making large adjustments in order to reduce the energy consumption of the servo mechanism and reduce mechanical wear. Only very small adjustments are allowed to counteract the drift. Conversely, if the deviation exceeds the threshold, it means that the working condition has changed significantly and it is necessary to return to step S2 to continue to execute the complete closed-loop control cycle, recalculate the optimal target and make adjustments. The value can be set to the current value. The threshold should be 3% to 5%, or a fixed value should be determined based on sea trial experience. The choice of this threshold should balance the requirements of control sensitivity and system stability.

[0043] Through the continuous operation of the above control methods, the wave energy buoy can automatically find and lock the optimal operating point of the air turbine under the ever-changing actual sea conditions. This not only improves the conversion efficiency of wave energy to mechanical energy, but also prevents the turbine rotor from being damaged due to excessive thrust under high air pressure. At the same time, when extreme sea conditions cause the liquid level change rate to be too large and the air chamber pressure to exceed the design limit, the controller can also quickly open the cam turntable 2 to the fully open state or the closed state (depending on the turbine type) to bypass or brake the airflow, playing a role in systemic safety protection.

[0044] To enable those skilled in the art to further understand and implement the present invention, the following supplementary description is provided in conjunction with the specific structural parameters and optional variations of this embodiment.

[0045] In this embodiment, the rigid buoy 7 can be made of corrosion-resistant aluminum alloy or fiberglass. The air chamber 7-2 has a circular cross-section, and its area A can be selected between 1 and 10 square meters. A filter screen can be installed at the water inlet 7-4 to prevent marine organisms from entering. The cavity 7-3 can adopt a structure of multiple watertight compartments, ensuring that the buoy will not sink even if there is partial damage. The turbine support 7-1 is fixed to the top of the rigid buoy 7 with bolts and is supplemented with vibration-damping rubber pads to absorb the vibration generated by the turbine operation.

[0046] The cam turntable 2 is preferably made of stainless steel. The angle and radius of the fan-shaped notch need to be designed according to the diameter of the air outlet to ensure coverage of the entire flow range from fully closed to fully open. The reduction ratio between the driving gear 3 and the driven gear 4 can be selected according to the rated speed of the servo motor 5 and the required cam positioning accuracy. Generally, to obtain sufficient adjustment torque and improve position accuracy, a reduction ratio of 3:1 to 10:1 can be used, while the gear module and number of teeth should meet the requirements of torque transmission and strength. The driven shaft 6 is rotatably supported on the rigid float 7 through a bearing housing. The bearings are seawater corrosion-resistant ceramic bearings or double-sided sealed stainless steel bearings.

[0047] The pressure sensor 11 should have a range that takes into account the maximum possible chamber pressure, for example, 0–5000 Pa, and should have an IP68 waterproof rating. The level sensor 12 preferably has a resolution of 1 mm or higher to accurately capture level changes caused by minute waves. These sensors transmit signals to the controller in the waterproof electrical compartment via watertight connectors.

[0048] The controller is pre-installed with control software. In addition to implementing the aforementioned control algorithms, it also features data logging and remote communication capabilities, enabling the transmission of information such as power generation, air chamber status, and equipment health to a shore-based monitoring center via a wireless network. The controller's power supply can be provided by the buoy's onboard battery pack, which is charged by a generator driven by an air turbine, or supplemented by solar panels.

[0049] Considering the long-term unattended operation of the wave energy power generation device, the system design incorporates several reliability measures. For example, the servo motor 5 is a model with a brake, which can maintain the cam position when power is off; the rotating parts of the drive gear 3, driven gear 4, and driven shaft 6 are all housed in protective covers and lubricated with long-lasting grease; a PTFE wear-resistant ring is installed between the cam turntable 2 and the air outlet 7-5 to prevent damage to parts in the event of slight contact; the control software includes a watchdog timer and a fault self-diagnosis module, which can automatically adjust the cam turntable 2 to a preset safe position (e.g., fully open) and issue an alarm when a sensor failure or servo motor overload is detected.

[0050] The device structure of the present invention is not limited to the specific mechanical form described above. For example, in the spirit of the present invention, the cam turntable 2 can be replaced by other structures with similar variable throttling functions, such as a butterfly valve plate that can rotate around a central axis or a slide valve that translates along a guide rail. However, the cam turntable has the advantages of strong self-cleaning ability and good torque characteristics, making it more suitable for humid airflow in marine environments. Furthermore, the gear pair transmitting power can be replaced with a worm gear drive, thereby utilizing its self-locking characteristics to prevent the airflow thrust from acting on the cam; however, spur gear drives have higher efficiency and a more compact structure, and the servo motor itself has braking capabilities, therefore, they are preferred in this embodiment.

[0051] The number of connecting rods 8 can also be three, six, or more; even distribution ensures connection strength. Through holes can also be made on the heave plate 9 to increase damping and reduce buoy roll; the holes can be circular or grid-like. The entire buoy system can vary its mooring method according to different water depths and environmental conditions, such as using single-point mooring or multi-point tensioning mooring.

[0052] In another modified embodiment of the invention, remotely controlled water inlet valves and air inlet valves can be added, mounted on the ballast water tank of the rigid buoy 7. By actively introducing or discharging seawater, the draft of the buoy can be adjusted, thereby changing its natural period to better match the dominant frequency of the incident waves. In extreme weather conditions, ballast water can be completely injected to allow the buoy to sink to a certain depth below the water surface to avoid wind and waves, and the ballast can be discharged to resume operation after the weather improves. This function further enhances the survivability and adaptability of the device.

[0053] Regarding the acquisition of parameters for the control method, the flow correction coefficient During the turbine design phase, a cluster of flow-efficiency-pressure ratio characteristic curves can be obtained through 3D flow simulation. Then, the operating points corresponding to each surge boundary and efficiency peak can be extracted and fitted. During prototype sea trials, multiple sets of wave level change rates can be collected. air chamber pressure Based on turbine speed data, the system identifies the operating point corresponding to the efficiency peak, thereby making corrections. and Flow coefficient CFD software can be used to perform steady-state simulations of the air outlet flow field under different cam rotation angles, calculate the mass flow rate, and inversely deduce the flow coefficient. Alternatively, model components can be fabricated and calibrated in wind tunnels or water tunnels using force / pressure measurements. The mapping relationship between cam rotation angle and flow area is also discussed. It can be directly derived from the geometric design formula of the cam, but considering the machining error and installation clearance, it is best to correct it by offline precision measurement of laser displacement sensor and flow meter, and then import the corrected lookup table into the controller.

[0054] The beneficial effects of this invention are significant: by using an electromechanical integrated variable cross-section adjustment mechanism, the previously passive fixed nozzle or staged throttling water column buoy is upgraded to an intelligent buoy that can actively seek the optimal turbine operating pressure based on real-time wave conditions. This achieves maximum dynamic tracking of wave energy capture efficiency and endows the system with the ability to withstand harsh sea conditions and self-protect. The device has a compact structure and fast adjustment response, making it particularly suitable for scenarios requiring reliable, long-life independent power supplies, such as island power supply, marine observation platforms, and seawater desalination drives.

[0055] The specific embodiments described above are merely illustrative and not restrictive. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention, such as changing the type of sensor, changing the controller algorithm to fuzzy control or model predictive control, replacing the cam turntable and air outlet with a multi-blade louvered adjustment mechanism, and expanding a single buoy to an array-based coordinated power generation, should be included within the scope of protection of this invention. The scope of protection of this invention is defined by the appended claims.

Claims

1. A wave energy generating buoy with adjustable air turbine flow rate, characterized in that, It includes an air turbine (1), a cam turntable (2), a drive gear (3), a driven gear (4), a servo motor (5), a driven shaft (6), and a rigid float (7); The rigid pontoon (7) has an air chamber (7-2) and a cavity (7-3) inside, a water inlet (7-4) at the bottom, an air outlet (7-5) at the top, and a turbine support (7-1) at the top. The air turbine (1) is fixedly installed by the turbine bracket (7-1) and is coaxial with the air outlet (7-5); The cam turntable (2) is rotatably disposed between the air outlet (7-5) and the air turbine (1), and has gaps between it and both the air outlet (7-5) and the air turbine (1), so as to change the effective flow area of ​​the air outlet by rotating it. The driven gear (4) and the cam turntable (2) are coaxially fixedly connected through the driven shaft (6). The driving gear (3) is fixedly installed on the output shaft of the servo motor (5) and meshes with the driven gear (4) for transmission. The servo motor (5) is fixed on the rigid float (7). A pressure sensor (11) and a liquid level sensor (12) are installed in the air chamber (7-2). The buoy also includes a heave plate (9) and a mooring ring (10). The rigid buoy (7) is fixedly connected to the heave plate (9) by multiple connecting rods (8), and the mooring ring (10) is fixed to the center of the heave plate (9).

2. The wave energy generating buoy with adjustable air turbine flow rate according to claim 1, characterized in that, The cam turntable (2) is a disc with a fan-shaped notch. The flow area is adjusted by rotating the notch to change the degree of overlap between it and the air outlet (7-5).

3. The wave energy generating buoy with adjustable air turbine flow rate according to claim 1, characterized in that, The connecting rods (8) are four in number and are evenly distributed along the circumference.

4. The wave energy generating buoy with adjustable air turbine flow rate according to claim 1, characterized in that, The driving gear (3) and the driven gear (4) are cylindrical spur gears.

5. The wave energy generating buoy with adjustable air turbine flow rate according to claim 1, characterized in that, It also includes a controller, which is electrically connected to the air pressure sensor (11), the liquid level sensor (12) and the servo motor (5) respectively, and is used to receive air pressure and liquid level signals, and output control signals to drive the servo motor (5) to move according to a preset control strategy.

6. A control method for a wave energy generating buoy with adjustable air turbine flow rate, wherein the wave energy generating buoy is the wave energy generating buoy according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: Collect real-time air pressure in the air chamber using a barometer. The water level in the gas chamber is collected using a liquid level sensor. ; Step S2: Determine the current working stage of the buoy based on the water level change. When the water level rises, it is determined to be the air venting stage; when the water level falls, it is determined to be the air intake stage. Step S3: Calculate the rate of change of liquid level in For water level, The optimal flow rate corresponding to the best efficiency of the air turbine is calculated based on the liquid level change rate over time. and optimal pressure Wherein, the optimal flow rate The optimal pressure The flow correction factor is determined based on the turbine surge boundary and efficiency peak fitting. The cross-sectional area of ​​the air chamber is... This is the air pressure correction factor; Step S4: Establish the optimal circulation area With optimal pressure The functional relationship, where For flow coefficient, Atmospheric pressure. air density; Step S5: Establish the rotation angle of the cam turntable With circulation area The mapping relationship is used to obtain the corresponding optimal pressure. Theoretical perspective The mapping relationship is obtained through pre-calibration, and the corresponding angle when the cam is fully closed is... The corresponding angle when fully open is Theoretical perspective Through function Sure; Step S6: Calculate the deviation between real-time pressure and optimal pressure. ; Step S7: Use a PID control algorithm based on the deviation. Calculate the angle fine adjustment amount ; Step S8: Control the servo motor to drive the cam turntable to rotate the total angle. This allows for the adjustment of circulation area; Step S9: Determine real-time air pressure Is it within the optimal pressure range? If the pressure is within the optimal range, maintain the current cam disc opening and make minor adjustments; otherwise, return to step S2 to continue closed-loop control. This is the allowable deviation threshold.

7. The control method according to claim 6, characterized in that, The flow correction coefficient mentioned in step S3 The pressure correction coefficient is obtained by fitting the surge boundary and efficiency peak of the air turbine; The matching characteristics between the air chamber and the turbine were obtained through experimental calibration.

8. The control method according to claim 6, characterized in that, The flow coefficient mentioned in step S4 The geometry of the cam turntable (2) and the structure of the air outlet (7-5) are determined by fluid simulation or calibration tests.

9. The control method according to claim 6, characterized in that, The mapping relationship described in step S5 was obtained through experimental calibration, where the angle corresponding to the cam being fully closed is... Corresponding angle when fully open Limited by the mechanical structure of the cam turntable (2).

10. The control method according to claim 6, characterized in that, The allowable deviation threshold mentioned in step S9 Set to current optimal pressure 3% .

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