Floatable wave energy converter and method for controlling the movement of a floatable wave energy converter

Abstract

The aim of the invention is to provide a floatable wave energy converter (100) which has a high degree of efficiency and can also be simply and cost-effectively produced and installed. This is achieved by providing a floatable wave energy converter (100) for converting energy from a wave movement of a fluid into electric energy, comprising a rotor unit (10) having a rotor shaft (11) and rotor support surfaces (12) for generating a buoyancy force (71) which is induced by the wave movement and rotates the rotor unit (10), a generator (20) for generating electric energy, the generator (20) being coupled to the rotor shaft (11) of the rotor unit (10) in order to transmit a torque, and a receiving structure (30) for receiving the rotor unit (10) and the generator (20), the wave energy converter (100) having a control element (40), which comprises at least one movable guiding surface (41), for controlling the movement of the wave energy converter (100) in the sea.

Description

[0001] Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0002] 1

[0003] Floating wave energy converter and method for motion control of a floating wave energy converter

[0004] The invention relates to a floating wave energy converter for converting energy from a wave motion of a fluid into electrical energy and to a method for controlling the motion of a floating wave energy converter.

[0005] In light of global warming, the use of renewable energies is becoming increasingly important. Wave energy converters, also known as wave power plants, harness the energy of ocean waves to generate electricity. As a sustainable and emission-free alternative to fossil fuels, they can play a significant role in a diversified energy mix alongside solar and wind power in the future.

[0006] Among other things, wave energy converters with a rotor unit are known, also called rotor-wave power plants. These aim to generate torque from the relative motion of the fluid and the rotating rotor unit, which is then converted into electrical energy by means of a generator. This requires a reaction torque from the wave energy converter that holds the generator.

[0007] Rotor wave power plants with rigid foundation structures are known, in which the reaction forces are generated via the anchoring or foundation through the seabed. The foundation, through which the forces induced in the rotor unit of the wave energy converter are transferred to the seabed, is realized, for example, by monopiles (WO 2014 / 026027 A2).

[0008] One disadvantage is the significant cost and time required for constructing a foundation. This is all the more problematic because wave energy converter rotor units are ideally deployed in medium water depths of 50 to 100 meters, which often makes the foundation particularly complex. Furthermore, wave-induced forces combined with a fixed foundation lead to undesirable fatigue phenomena occurring prematurely.

[0009] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0010] 2 of the material used. In addition, the cyclic wave movements often cause so-called scour effects, whereby the sections of the foundation structure anchored in the seabed can be dug out (shaked out) again by the induced forces and thus endanger the structural integrity of the foundation.

[0011] In addition to rotor wave power plants with rigid foundations, floating wave energy converters, particularly those with a rotor unit, are known. These floating wave energy converters are self-supporting, usually (mostly) below the water surface. These systems often have an anchorage, which, however, provides little or no reaction torque but is primarily intended to prevent the floating wave energy converter from drifting. Considering the wave-induced first-order forces, the forces of the rotor unit and the forces exerted by the rotor shaft on the structure of the wave energy converter generate an oscillating motion of the floating wave energy converter.

[0012] The induction of this movement of the wave energy converter has so far been considered parasitic with regard to energy extraction, since the movement can lead to a significant reduction in the achievable power. If the amplitude of the wave energy converter's movement corresponds to the amplitude of the wave motion, as can be the case, for example, in diving motion at low excitation frequencies or in the resonance range, the wave-induced flow velocity at the rotor unit's airfoils is neutralized by the substructure movement, and no or only very little thrust can be generated (EP 2 535 557 A2).

[0013] To reduce these parasitic effects of wave-induced motion in floating wave energy converters, floating rotor wave power plants are known from the prior art, in which several rotor units are mounted offset in the direction of wave motion (wave propagation direction) (US 9,297,351 B2; EP 1 878 914 Bl). This sequential arrangement achieves a phase shift in the orientation of the wave-induced rotor forces. For example, if a harmonic wave and a system with two rotor units are considered, the orientation of the rotor forces can be oppositely aligned.

[0014] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0015] 3. This will occur when the distance between the two rotor units corresponds to half a wavelength. This is intended to neutralize the forces and prevent or reduce unwanted movements of the floating wave energy converter caused by wave-induced forces.

[0016] However, the efficiency of these multi-rotor systems depends on the ratio of rotor spacing to wavelength. In energy-rich coastal regions, wavelengths often exceed 150 m, resulting in very large frame and coupling structures. These systems are therefore correspondingly expensive to design and install. Furthermore, the large distances between the force application points result in enormous bending and torsional moments within the structure. Another disadvantage is the operation of the second rotor in the wave shadow of the first. Disturbance of the wave field and the prior energy extraction by the first rotor make efficient operation difficult.

[0017] The invention is based on the objective of providing a floating wave energy converter and a method for controlling the motion of a floating wave energy converter, thereby avoiding the aforementioned disadvantages. In particular, the objective is to provide a floating wave energy converter with high efficiency that can also be manufactured, installed, and operated simply and cost-effectively.

[0018] The problem according to the invention is solved by a floating wave energy converter for converting energy from the wave motion of a fluid into electrical energy, comprising a rotor unit with a rotor shaft and rotor wings for generating a lift force induced by the wave motion and causing the rotor unit to rotate, a generator for generating electrical energy, wherein the generator is coupled to the rotor shaft of the rotor unit for torque transmission, and a mounting structure for receiving the rotor unit and the generator, wherein the wave energy converter has a control element, comprising at least one movable guide surface, for controlling the movement of the wave energy converter. The wave energy converter is expediently used in the sea so that the fluid is seawater and by means of

[0019] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0020] 4 of the control element, the movement of the wave energy converter in the sea can be controlled.

[0021] By providing a control element with at least one movable guide surface, the (dynamic) movement behavior of the floating wave energy converter can be specifically modified and utilized to increase energy extraction and thus the performance of the wave energy converter. The control element allows for targeted modification of the hydrodynamic properties of the wave energy converter, such as its natural frequency, or the phase and / or amplitude of its movement. This improves the efficiency of the wave energy converter, particularly by increasing its reaction forces in response to the forces induced by the wave motion. This can be achieved by appropriately controlling the control element.The at least one guide surface allows for the targeted reduction or induction of translational and / or rotational movements of the entire floating structure of the wave energy converter, in order to induce a desired movement in the wave energy converter, which is particularly phase-shifted to the wave motion. This means that the wave energy converter does not follow the wave motion, but moves in a different direction, for example, opposite to or perpendicular to the wave motion. This allows, for example, an increase in the effective radius of the rotor unit and / or the relative flow velocity of the rotor unit, thereby achieving higher thrust forces at the rotor blades. As a result, a higher average power output can be achieved compared to known floating wave energy converters. Furthermore, a complex and inefficient design with multiple rotor units arranged in series is not necessary.Compared to wave energy converters with fixed foundations, the wave energy converter according to the invention is also efficient and can often even exceed the power output of wave energy converters with fixed foundations, without the need for a complex and costly foundation structure. Furthermore, by appropriately controlling the control element, the spectrum of wave frequencies that can be efficiently used for energy generation can be increased.

[0022] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0023] 5

[0024] The movement behavior of the wave energy converter according to the invention differs from that of known wave energy converters and is not exclusively passive, but can be actively influenced or controlled by the control element with the at least one movable guide surface. Preferably, the control element is activated and / or influenced depending on the current and incoming wave movement(s), the position of the wave energy converter and the rotor unit, and / or the loads acting on the wave energy converter.

[0025] Preferably, the control element is designed to generate a movement of the wave energy converter that is phase-shifted relative to the wave movement.

[0026] The wave energy converter will typically be used in the ocean. However, in principle, it can also be used in other bodies of water.

[0027] Preferably, the wave energy converter comprises exactly one rotor unit. In particular, multiple rotor units arranged one behind the other in the direction of the wave motion are not provided. Because the wave energy converter according to the invention has a control element and can thus execute a phase-shifted movement relative to the wave motion, the efficiency is improved to such an extent that only one rotor unit is necessary, and complex, expensive, and inefficient frame constructions with multiple rotor units arranged one behind the other can be dispensed with.

[0028] The rotor wings are preferably arranged in a longitudinal direction essentially parallel to a rotor axis of the rotor unit and / or to the rotor shaft.

[0029] The floating wave energy converter is preferably designed such that the rotor unit is arranged completely below the water surface, particularly preferably at a water depth of 25 m to 125 m, and especially preferably at a water depth of 50 m to 100 m. At this depth, the energy yield or power extraction is generally higher than at other depths. The wave energy converter can also be completely or at least substantially partially submerged, e.g.,

[0030] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0031] 6. At least 80% of its total volume, preferably at least 90%, is located below the water surface.

[0032] The wave energy converter may preferably include an anchoring device, such as an anchor cable, with which the wave energy converter is anchored to the seabed. Such anchoring serves to compensate for the average drift forces acting on the floating wave energy converter and thus prevent it from drifting away. Additionally, the anchoring system may also be designed to provide a reaction force for the wave energy converter. Alternatively, the wave energy converter may be designed without an anchoring system, i.e., it may be free-floating.

[0033] Furthermore, the wave energy converter preferably has a connection for a submarine cable, with which the generated electricity can be transported from the wave energy converter to a consumer, for example on land.

[0034] The wave energy converter can have several movable guide surfaces, in particular at least two or at least four. If several guide surfaces are present, they can be designed to be movable independently of each other or together, i.e., dependently on each other. Accordingly, the guide surfaces can be individually or jointly controllable.

[0035] The at least one guide surface is distinct from the rotor support surfaces of the rotor unit, i.e., it is an independent, separate component.

[0036] One or more control elements can be provided, each control element having at least one movable guide surface. Preferably, each control element can have at least two, two to six, or three to five movable guide surfaces.

[0037] The wave energy converter may preferably have one or more buoyancy elements to ensure its buoyancy. The buoyancy elements may, in particular, be partially located above the water surface.

[0038] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0039] 7. Alternatively or additionally, the wave energy converter can also include stabilizers, ballast bodies or other floating structures.

[0040] The wave energy converter can have exactly one generator or several generators, in particular exactly two generators.

[0041] Preferably, the wave energy converter comprises a control unit configured to receive sensor data on wave motion and to control the control element and / or the at least one movable guide surface based on the received sensor data. The control unit can, in particular, include a processor and a memory unit. The memory unit can store data such as empirical data, simulation models, etc., which are also used to determine the control of the at least one guide surface. The control unit can directly control the control element based on the received sensor data and, optionally, on the basis of other stored or transmitted data, or it can generate or calculate predictive models based on this data, which then, in turn, form the basis for the control.

[0042] The wave motion, whose sensor data can be transmitted to the control unit, is expediently a wave motion in the immediate vicinity of the wind energy converter; that is, it can be, in particular, current wave motions within which the wave energy converter is located, or the next or one of the next incoming wave motions. In other words, the wave motion whose sensor data is recorded and transmitted to the control unit can, in particular, be located upstream of the wave energy converter in the direction of wave propagation.

[0043] The control unit is preferably arranged within the mounting structure of the wave energy converter and thus rigidly connected to it. Alternatively, an arrangement outside the wave energy converter would also be possible, in which case the transmitter and receiver for communication with the control unit, particularly wireless communication, would preferably be provided on the wave energy converter. Wired communication would also be possible.

[0044] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0045] 8

[0046] The control unit can be configured to control each control element and / or guide surface individually, or to control all control elements and / or guide surfaces together, or subgroups of control elements and / or guide surfaces together.

[0047] Preferably, the wave energy converter includes at least one sensor for acquiring sensor data of a wave motion. Alternatively or additionally, the wave energy converter can preferably also be assigned at least one sensor for acquiring sensor data of a wave motion. In both cases, the at least one sensor is designed to transmit the sensor data to the control unit; that is, appropriate cabling or receivers and transmitters for wireless communication are provided. Particularly preferably, several sensors are provided that acquire the same data or other data of a wave motion. Further sensors can also be provided that acquire other data, such as the forces acting on the wave energy converter due to the wave motion. Assigned sensors can, in particular, be arranged on other components or devices separate from the wave energy converter.For example, buoys can be used on which the sensors are mounted, with the sensors then transmitting the acquired data to the wave energy converter, for example via appropriate cabling. Such associated sensors can be positioned, in particular, in the incoming wave field, that is, in the direction of wave propagation upstream of the wave energy converter.

[0048] Preferably, the sensor data of the at least one sensor can include one or more of the following types of data: data relating to the wave height, wave speed, wave period, wave amplitude or phase of a wave motion, data relating to the forces or accelerations acting by the surrounding fluid on the rotor unit, the receiving structure and / or the at least one guide surface, data relating to the position or orientation of the rotor unit, the receiving structure and / or the at least one guide surface.

[0049] For example, fluid velocity can be measured using ADV / ADCP sensors (Acoustic Doppler Velocimeter / Acoustic Doppler Current Profiler), or such sensors can be provided. Regarding wave detection,

[0050] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0051] 9. For data collection, non-invasive optical sensors, such as LiDAR or stereovision technology sensors, or acoustic measurement systems, for example based on ultrasound, can be used. Classic wave buoys can also be used as sensors, where wave properties can be determined from the wave-induced motion via accelerometers using Fourier transformation. Accelerometer sensors can also be installed directly on the wave energy converter. These then measure, in particular, the acceleration of the recording structure or the wave energy converter. Encoders can also be used as sensors to measure the rotational position of the rotor unit and / or the rotor blades, especially continuously. Furthermore, force and / or torque sensors can be used as alternative or additional sensors, which, for example, measure the loads acting on the rotor blades or on the rotor's suspension.Measure the loads acting on the rotor shaft.

[0052] In addition to controlling the control element and / or the at least one guide surface, all or some of the sensor data transmitted to the control unit can also be used for calibrating the control unit.

[0053] Preferably, the at least one movable guide surface has an airfoil profile or is formed by an airfoil. Such a design of the guide surface allows for particularly effective movement control of the wave energy converter. However, the guide surface can also have a different profile, for example a rectangular profile, and be designed as a plate or similar. In any case, the at least one guide surface is a planar component that can influence the incoming flow and thus affect the movement of the wave energy converter in the sea.

[0054] Preferably, the at least one guide surface is movable by means of a drive, which is furthermore preferably controllable by the control unit. The movement of the at least one guide surface generated by the drive can in particular be a rotation of the at least one guide surface, for example about its longitudinal axis, or another axis of rotation, in particular parallel to the longitudinal axis. Alternatively or additionally, the movement of the at least one guide surface can be a translational movement, in particular relative to a rotor axis and / or to the rotor shaft of the Ro-

[0055] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0056] The guide surface can be a 10-gate unit. It is also possible for the at least one guide surface to be both rotatable and translationally movable. Furthermore, movement along the longitudinal axis of the guide surface is also possible. The various movements can also be superimposed. The translational movement can, in particular, be orthogonal and / or radial to the rotor axis or in the direction of the rotor axis. If the movement includes a rotation about the longitudinal axis of the at least one guide surface, this can change the angle of attack of the guide surface relative to the incoming wave motion. This is particularly preferred in the case of a guide surface with an airfoil profile. A drive can be configured to drive several guide surfaces. Alternatively, one, in particular exactly one, drive or even several drives can be provided per guide surface, whereby the drive(s) then drive only that one guide surface.

[0057] Preferably, the control element is arranged on an outer surface of the receiving structure of the wave energy converter, particularly in the imaginary extension of the rotor unit. Alternatively or additionally, the at least one guide surface can be attached at one end to a base body of the control element and / or to the receiving structure, and the other, opposite end of the at least one guide surface can be designed as a free end.

[0058] The arrangement of the receiving structure as an imaginary extension of the rotor unit is to be understood in particular as follows: the control element, which is arranged primarily on the outside of the receiving structure, is positioned behind or in front of the rotor unit in the longitudinal direction. The imaginary extension is to be considered in the longitudinal direction of the rotor unit.

[0059] The attachment of at least one guide surface to the base body of the control element or the receiving structure can be done directly or with an intermediate mounting element.

[0060] In particular, the guide surface in this embodiment can be elongated, which is especially the case when configured as a wing. In this case, the end faces form the end regions with which the guide surface is connected to the receiving structure and / or the base body of the control element.

[0061] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0062] 11 or which are designed as a free end. Flow elements, such as winglets or caps, can be provided at the end region of the guide surface designed as a free end. Preferably, more than one, and in particular exactly two, control elements can be provided, which are preferably arranged on opposite sides of the receiving structure and in particular on opposite sides of the rotor unit, especially in its imaginary extension.

[0063] The basic body of the control element can be embedded in the receiving structure and / or shielded or encapsulated, so that it is protected in particular from penetrating seawater.

[0064] Preferably, the base body of the control element can be rotatably mounted, in particular via a shaft, wherein the shaft is preferably rotatable by means of a drive, which is preferably controllable by the control unit. This allows the base body of the control element, in particular together with the at least one guide surface attached to the base body, to be rotated. This allows a rotation about another axis of rotation, preferably parallel to the longitudinal axis of the at least one guide surface, to be implemented. In particular, the axis of rotation can correspond to the shaft axis of the shaft on which the base body is preferably rotatably mounted. Alternatively, particularly when the drive is absent or switched off, the guide surface attached to the base body can be designed to convert the lift induced by the shaft movement into a rotation of the base body. Preferably, the base body can be rotatably mounted on the receiving structure.Furthermore, the shaft can be formed by the rotor shaft of the rotor unit, or alternatively, it can be a separate shaft. Direct or indirect coupling of the base body and / or the shaft of the base body with the rotor shaft is also possible.

[0065] Preferably, the drive, which is designed to move the at least one guide surface, can comprise one or more electrical actuators, such as servo motors, and / or mechanical actuators, such as a mechanical coupling device, in particular for direct or indirect coupling with the rotor shaft. A combination of electrical and mechanical actuators is also possible. Indirect coupling can, for example, preferably be achieved via a gearbox. The drive(s)

[0066] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0067] 12 and the coupling mechanisms can preferably be encapsulated and thus protected from seawater.

[0068] Preferably, the wave energy converter has an additional control element for controlling its movement in the sea. This additional control element is preferably controllable by the control unit and, in particular, comprises a drive for adjusting the angle of attack of one or more rotor blades, means for changing the shape of the additional control element, and / or ballast elements. The additional control element is present in addition to the first control element and serves to control or move further control means besides the at least one movable guide surface. Changing the shape of the additional control element can alter its hydrodynamic structural response (for example, its natural frequency), thereby further influencing the movement of the wave energy converter.Similarly, a change in motion can be induced by altering the angle of attack of the rotor blades of the rotor unit, as well as by manipulating ballast elements present on the wave energy converter. Manipulating or controlling the ballast elements changes the moment of inertia of the wave energy converter, which in turn influences its motion. The movements generated by the additional control element are preferably in addition to the movements generated by the control element and generally superimpose with them.

[0069] The problem underlying the invention is further solved by a method for controlling the motion of a floating wave energy converter, comprising the following steps:

[0070] Acquisition of sensor data of a wave movement using at least one sensor;

[0071] Transmission of sensor data to a control unit of the wave energy converter;

[0072] Control of a control element, in particular a movable guide surface, of the wave energy converter based on the transmitted sensor data

[0073] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0074] 13 by the control unit to generate a movement of the wave energy converter that is out of phase with the wave movement.

[0075] The wave energy converter of the method can preferably be configured as described above and may include any of the various preferred embodiments and combinations thereof.

[0076] If a floating wave energy converter moves in phase with the wave motion, i.e., follows the vertical motion of a wave, this reduces the relative flow velocity at the rotor blades of the rotor unit and / or decreases the angle of attack at the rotor blades of the rotor unit. This results in reduced achievable thrust and thus lower power extraction. By generating a phase-shifted, i.e., out-of-phase, particularly anti-phase, motion using the method according to the invention, in which the wave energy converter does not follow the wave motion, the power extraction of the wave energy converter can be increased accordingly, since the phase-shifted motion increases the reaction force of the wave energy converter and / or the receiving structure of the wave energy converter.The movement of the floating wave energy converter is, in particular, phase-shifted relative to the wave movement of the wave within which the wave energy converter is currently located. Alternatively, the control can also be relative to the next, the next-but-one, or nth incoming wave movement (i.e., arriving at the wave energy converter). The out-of-phase movement can preferably be an opposite or orthogonal movement with respect to the wave movement, or a movement in between.

[0077] The method according to the invention is preferably used in wave energy converters with a rotor unit, also called rotor-shaft power plants. In the method according to the invention, the sensor data of the wave movement, which are acquired and transmitted to the control unit, are used to achieve a desired movement (which is power-optimized) and to control the control element accordingly. In particular, various sensor data from different sensors can be used.

[0078] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0079] 14 sensors can be used. Furthermore, the transmission of sensor data can be continuous or periodic.

[0080] The control element preferably comprises or consists of at least one movable guide surface. In this case, the movable guide surface is then controlled. The movable guide surface can, in particular, be a separately provided guide surface, which is especially attached to the outside of the wave energy converter and is not part of the rotor unit. Alternatively, the movable guide surface can also comprise a rotor support surface of a rotor unit of the wave energy converter.

[0081] Preferably, in this method, the control unit determines the wave-induced motion excitation of the wave energy converter based on the transmitted sensor data. Furthermore, the control unit determines an optimal motion of the energy converter with regard to achieving the desired thrust of a rotor unit of the wave energy converter. The control unit then controls the control element in such a way that the wave-induced motion excitation is modified to achieve the determined, optimal motion of the wave energy converter. The optimal motion is therefore preferably the one in which, according to the control unit's calculations based on the transmitted sensor data, the maximum power output and / or the maximum thrust of the rotor unit is calculated or determined. Alternatively, a minimum value can be set instead of the maximum power output.Furthermore, the optimal movement is always an antiphase movement of the wave energy converter with respect to the movement of the wave.

[0082] Preferably, the control unit performs the control of the control element periodically or continuously. Periodic control can, in particular, be a repetitive control at short time intervals, for example, several times per second, so that changing, dynamic influences of the wave motion are constantly incorporated into the control and the movement of the wave energy converter can always be kept as optimal as possible with regard to maximum power extraction. In continuous control, calculations are performed continuously and the control element is actuated continuously.

[0083] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0084] 15

[0085] Preferably, in this method, the control unit, using the transmitted sensor data and optionally other data such as dimensions or hydrodynamic parameters of the wave energy converter or empirical data on wave motions, determines a phase-shifted motion of the wave energy converter relative to the wave motion, in particular an optimal motion of the wave energy converter, using simulation models, and controls the control element accordingly. Advantageously, the control unit can use a combination of different data types and simulation models to determine as precisely as possible a desired, and in particular optimal with regard to power extraction, phase-shifted motion of the wave energy converter relative to the wave motion, and then control the control element accordingly.

[0086] Preferably, in this method, the control unit uses simulation models to make predictions about future wave movements, particularly regarding the wave cycle that follows a given time, and the control unit uses these predictions to determine the optimal phase-shifted movement. Predictions for multiple wave cycles are also preferably generated and usable. The wave cycle refers to the incoming waves, i.e., those that will next strike the wave energy converter. The use of predictions can advantageously help to further improve or optimize the determination of the desired movement and, consequently, the corresponding control of the control element.

[0087] Preferably, in this method, the control unit can perform a calibration step based on sensor data regarding the forces and / or moments acting on the wave energy converter or its components. This calibration step can be performed as needed or periodically.

[0088] The invention is explained in more detail below using exemplary embodiments. The schematic representations show:

[0089] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0090] 16 a representation of the known principle of thrust generation of a rotor surface of a rotor unit of a wave energy converter, a representation comparing the lift generation during an uncontrolled and a controlled movement according to the invention of a wave energy converter, a perspective view of a first embodiment of a wave energy converter, a perspective view of a second embodiment of a wave energy converter,

[0091] Illustrations of various embodiments of control elements, and A flowchart of an exemplary procedure for determining the control of the control element.

[0092] In wave energy converters with rotor unit(s) (so-called "rotor wave power plants"), the wave forces acting on the rotor surfaces generate a rotor motion, namely a rotation of the rotor unit, which can be used to generate thrust and thus ultimately to produce energy. The basic, well-known principle of thrust generation is illustrated in Fig. 1. Fig. 1 shows the cross-section of a rotor surface 12 of a rotor unit of a wave energy converter, which—when the rotor unit rotates due to the wave—moves along a rotor path 13 indicated by the dashed line. From a wave-induced velocity 74 and a relative velocity (or speed of motion) 75 resulting from the rotation of the rotor unit, a velocity 76 of the absolute relative flow is obtained.As long as the wave-induced and rotor-induced velocity vectors (74 and 75) are not parallel, the resulting velocity 76 of the absolute relative flow is oblique to the tangential path of the rotor 13. Under oblique flow on the airfoil 12, a lift force 71 is generated, the vector of which is perpendicular to the flow velocity vector 76 and thus to the flow direction. In airfoils, the lift forces are often many times greater than the drag forces, which by definition are oriented in the direction of the flow. This is evident from the vectors 76, 71, and 73 (drag) shown here.

[0093] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0094] 17

[0095] The desired scenario, as shown in Fig. 1, is one in which the tangential component of the lift force 71 is greater than the tangential component of the drag force 73. This results in a thrust force 72 that acts in the direction of rotation of the rotor unit.

[0096] To utilize this propulsion for energy generation, a reaction force between the rotor and the generator or the receiving structure of the wave energy converter is required. According to the invention, this is achieved by selectively controlling the movement of the wave energy converter, particularly with regard to an antiphase movement, whereby regular restoring forces, e.g., hydrostatic forces, can also be taken into account.

[0097] Figures 2a and 2b, similar to Figure 1, show a cross-section of a rotor surface 12 on a rotor path 13 of a rotor unit of a floating wave energy converter. In wave energy converters that are moved purely passively by the wave motion, the wave energy converter generally moves in phase with the wave or approximately in phase with the wave, thus following, for example, the vertical motion of the wave, as shown in Figure 2a (see vectors 74 (wave-induced velocity vector; indicates the direction of the wave motion) and 77 (velocity vector of the motion of the wave energy converter; indicates the direction of the wave motion)). This results in small or reduced speeds of the relative flow 76 and angles of attack 78, leading to low power extraction. In extreme cases, the power extraction can approach zero.

[0098] By providing a control element according to the invention, which allows the movement of the wave energy converter to be controlled in a targeted manner, the power extraction can be significantly increased. As shown in Fig. 2b, according to the invention, for example, a phase-shifted movement 78 of the wave energy converter can be achieved compared to the wave movement 74. In Fig. 2b, an opposite movement 78 of the wave energy converter to the wave movement 74 is shown. By modifying the movement of the wave energy converter to an antiphase movement, the angle of attack 78 and / or the velocity of the relative flow 76 are significantly increased in contrast to Fig. 2a.

[0099] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0100] 18 gert, which results in a significantly higher thrust 72 on the rotor wing 12 and thus ultimately a greater power extraction.

[0101] The arrows shown in Figures 1, 2a, and 2b are vector arrows representing forces and / or velocities of flows, thus indicating both magnitude and direction. Figures 2a and 2b schematically depict a wave energy converter 100 above, with the respective direction of motion of the wave energy converter 100 indicated by arrow 77. It can be seen that only a small, upper part of the wave energy converter 100 protrudes above the water surface 20.

[0102] Fig. 3 shows a first embodiment of a wave energy converter 100 according to the invention in a perspective view. The wave energy converter 100 comprises a receiving structure 30, which in turn comprises two side walls 33, each having a circular upper region 331 and a lower region 332 adjoining it downwards and tapering downwards. The two side walls 33 are essentially mirror images of each other and are spaced apart and opposite one another, and are connected by a stabilizer element 32 attached to each lower end of the lower regions of the side walls 332. The stabilizer element 32 is designed to ensure a stable position of the wave energy converter 100 in the water. A rotor unit 10 is arranged inside the receiving structure 30 and between the respective upper regions of the side walls 331.This comprises two rotor blades 12, arranged opposite each other and point-symmetrically, and an internal rotor shaft 11 located between the two rotor blades 12. The rotor shaft 11 runs along the longitudinal direction of the rotor unit 10 and projects into the two upper regions of the side walls 331 (not shown here). A generator (not shown here) is provided in one of the upper regions of the side walls 331, to which the rotor shaft 11 is coupled for torque transmission. The rotor shaft 11 is rotatably mounted in the other, opposite upper region of the side wall 331. It would also be possible to provide a second generator there. The rotor blades 12 rotate around the rotor axis located inside the rotor shaft 11 due to induced shaft forces. The rotor shaft 11 is mounted externally on the circular upper regions of the side walls 331.

[0103] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0104] Each of the 19 control elements 40 is arranged with two movable guide vanes 41 designed as airfoil profiles. The control elements 40 comprise a base body 42 designed as a round plate, which is embedded in the side wall 33. The guide vanes 41 project outwards from the base body 42 essentially perpendicularly and are arranged in the upper, circular area of ​​the side walls 331. The two guide vanes 41 on each side are arranged opposite each other and are point-symmetrical to each other. Furthermore, the two guide vanes 41 of one side wall 33 are arranged as mirror images of the guide vanes 41 of the other side wall 33. The guide vanes 41 can be controlled and moved by actuators (not shown). For example, the guide vanes 41 can be rotated about their longitudinal axis so that the angle of attack is changed. Translational displacement along the surface of the side wall 42 is also possible.It would also be conceivable to design the wave energy converter 100 in such a way that the guide surfaces 41 can be displaced along their longitudinal axis, i.e., into or out of the side wall 42. The guide surfaces 41 are attached at one end face to the base body 42 or to drives (not shown) installed on the receiving structure 30, and have a free end face on their opposite end face. Alternatively, the drives can also be located on the base body 42. Cylindrical buoyancy elements 31 project upwards from the upper surface of the side walls 33 of the receiving structure 30. These extend vertically upwards, as shown in the drawing. In the floating state of the wave energy converter 100, the buoyancy elements 31 can be located, in particular, with their upper section partially above the water surface and the remainder below the water surface.In particular, during floating operation, the complete receiving structure 30 with the rotor unit 10 and the stabilizer element 32 is arranged below the water surface.

[0105] Figure 4 shows a second embodiment of a wave energy converter 100. The second embodiment according to Figure 4 is essentially identical to the first embodiment according to Figure 3, so the corresponding explanations also apply. In contrast to the first embodiment, the second embodiment of Figure 4 has four movable guide surfaces 41 for each control element 40. These are arranged circularly or annularly on the base body.

[0106] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0107] 20 per 42 of the control element 40 are arranged. Both side walls 333 each have a control element 40 that is mirror-image.

[0108] Figures 5a to 5c show different embodiments of control elements 40. All three control elements 40 each have guide surfaces 41 designed as airfoil profiles. These guide surfaces 41 are each connected at one end face to an actuator 43 by means of connecting elements 46. The actuators 43 can be controlled by a control unit (not shown). In particular, the actuators 43 can be controlled individually, so that in all three embodiments the guide surfaces 41 can be controlled and moved separately. In all three examples, the actuators 43 are designed to rotate the guide surfaces 41 so that the respective angle of attack of the guide surfaces 41 can be varied. In Figure 5a, the two actuators 43 are connected by means of a connecting strut 44. A shaft journal 45 projects vertically outwards from the center of the connecting strut 44.This shaft journal can be rotated by means of a further drive, not shown here, so that the guide surfaces 41 can be rotated not only about their own axis but also about the axis of the shaft journal 45. In the embodiment shown in Fig. 5b, compared to the embodiment shown in Fig. 5a, an additional cover plate 47 is provided, which covers the connecting struts 44 on the outside. In particular, the cover plate 47 can be made watertight, so that it protects the mechanism of the connecting struts 44 and also the actuators 43 attached to them from seawater. When the shaft journal 45 is rotated, the connecting strut 44 and also the cover plate 42 are rotated together with it. The cover plate 47 and / or the connecting strut 44 can form the base body of the control element 40. Both embodiments according to Figs. 5a and 5b each have two opposing guide surfaces 41.In contrast, the embodiment according to Fig. 5c has four guide surfaces arranged in a ring at equal intervals. Unlike the embodiments according to Figs. 5a and 5b, the embodiment of Fig. 5c does not have a connecting strut between the actuators 43. Instead, the actuators 43 are mounted on the inside of the cover plate 47.

[0109] Both the connecting struts 44 and the cover plate 42 can individually or together form a basic body of the control element 40.

[0110] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0111] Fig. 6 shows a flowchart of an exemplary method for determining a preferred or optimal movement of a wave energy converter with regard to power extraction, based on which the wave energy converter can be controlled. In particular, the method can reactively or predictively determine the motion excitation by the wave and subsequently adjust the control to achieve the desired motion behavior. In a first step S1, the incoming wave field is determined at time t0 using appropriate sensors. From this, a prediction of the predominant frequency components, amplitudes, and phase angles is determined. In a second step S2, based on the prediction data from S1, an in-phase response of the guide vane angles of attack for all frequency components is determined using Theodorsen's airfoil theory.These are superimposed to obtain the most uniform response possible to the resulting lift forces at the guide surface. In a third step, S3, the initial coefficients of the control response are determined based on the results from S2. These coefficients provide an initial setpoint for the control over the next wave cycles n*T. In a fourth step, S4, a prediction of the wave signal in the form of elevation and velocity at the rotor unit is calculated for the next wave cycles n*T. In a fifth step, S5, the coefficients are iterated using numerical optimization methods, taking into account nonlinear lift and separation effects. This optimization consists of several steps: a) Determining the relative flow at the guide surface from the results of S3 and S4 and iteratively calculating the lift and drag forces in the time domain or in state space; b)) Determination of the wave energy converter motion due to the wave-induced forces; c.) Determination of the resulting total motion for each time step in the interval t0 <t<t0+ n*T , beispielsweise durch iterative Berechnung in expliziten Zeitverfahren oder direkte Kopplung in höherwertigen Zeitverfahren (z.B. Runge- Kutta); d.) Ermittlung der resultierenden Gesamtleistung im betrachteten Zeitfenster n*T; e.) Anpassung der Kontrollkoeffizienten in Form von Amplituden und Phasenwinkeln die als Schwingungen der Leitflächenanstellwinkel und Rotorgeschwindigkeit aufgebracht werden. In einem sechsten Schritt S6 wird nach Konvergenz der Kontrolloptimierung die Ansteuerung der Leitfläche, insbesondere der Tragflügelanstellwinkel und der Rotorgeschwindigkeit, für einen bestimmten zeitlichen Horizont At = ti.

[0112] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0113] 22

[0114] - t0 is set. According to this set control, at least one guide surface can then be controlled. The endpoint of this time interval ti serves as the new starting point for the following optimization sequence. In a seventh step S7, the exact position of the wave energy converter, rotor angle, and guide surface angles of attack are updated based on real-time measurements, so that no accumulated error of significant magnitude occurs. The process then starts again from S1.

[0115] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0116] Reference symbol list

[0117] 100 wave energy converters

[0118] 10 rotor units

[0119] 11 Rotor shaft

[0120] 12 rotor blades

[0121] 13 Rotor track

[0122] 20 Water surface

[0123] 30 Recording structure

[0124] 31 buoyancy elements

[0125] 32 Stabilizer element

[0126] 33 side walls

[0127] 331 upper area side wall

[0128] 332 lower area side wall

[0129] 40 Control element

[0130] 41 Guide surface

[0131] 42 basic shapes

[0132] 43 Actuator

[0133] 44 Connecting strut

[0134] 45 wave pins

[0135] 46 connecting elements

[0136] 47 Cover plate

[0137] 50 Sensor

[0138] 60 Control unit

[0139] 71 Buoyancy force

[0140] 72 Propulsive force

[0141] 73 Resistance

[0142] RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025

[0143] 24 4 wave-induced velocity 5 relative velocity 6 absolute velocity relative flow 7 velocity of the wave energy converter 8 angle of attack

[0144] RGTH T241419W007718PT

Claims

Hamburg University of Technology (TUHH) Public corporation 26.11.2025 25 Claims 1. Floating wave energy converter (100) for converting energy from a wave motion of a fluid into electrical energy, comprising a rotor unit (10) with a rotor shaft (11) and rotor support surfaces (12) for generating a lift force (71) induced by the wave motion and causing the rotor unit (10) to rotate, a generator for generating electrical energy, wherein the generator is coupled to the rotor shaft (11) of the rotor unit (10) for torque transmission, and a receiving structure (30) for receiving the rotor unit (10) and the generator (20), characterized in that the wave energy converter (100) has a control element (40) comprising at least one movable guide surface (41) for controlling the movement of the wave energy converter (100).

2. Wave energy converter (100) according to claim 1, wherein the wave energy converter (100) comprises a control unit (60) which is configured to receive sensor data of a wave motion and to control the at least one guide surface (41) on the basis of the received sensor data.

3. Wave energy converter (100) according to claim 2, wherein the wave energy converter (100) has at least one sensor (50) for detecting sensor data of a wave motion or wherein at least one sensor (50) for detecting sensor data of a wave motion is assigned to the wave energy converter (100), wherein the at least one sensor (50) is configured for transmitting the sensor data to the control unit (60).

4. Wave energy converter (100) according to claim 2 or 3, wherein the sensor data comprise one or more of the following data types: Data relating to wave height, wave speed, wave period, wave amplitude or phase of a wave motion, data relating to the influence of the surrounding fluid on the rotor unit (10), which RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025 26 Forces or accelerations acting on the receiving structure (30) and / or the at least one guide surface (41), data relating to the position or orientation of the rotor unit (10), the receiving structure (30) and / or the at least one guide surface (41).

5. Wave energy converter (100) according to one of the preceding claims, wherein the at least one guide surface (41) has an airfoil profile or is an airfoil.

6. Wave energy converter (100) according to one of the preceding claims, wherein the at least one guide surface (41) is movable by means of a drive, which is preferably controllable by the control unit (60), wherein the movement of the at least one guide surface (41) is in particular a rotation of the at least one guide surface (41) about its longitudinal axis, a rotation about another axis of rotation, preferably parallel to the longitudinal axis of the at least one guide surface (41), and / or a translational movement, in particular relative to a rotor axis of the rotor unit (10).

7. Wave energy converter (100) according to one of the preceding claims, wherein the control element (40) is arranged on an outside of the receiving structure (30), in particular in an imaginary extension of the rotor unit (10), and / or wherein the at least one guide surface (41) is attached with one end region to a base body of the control element (40) and the other, opposite end region of the at least one guide surface (41) is designed as a free end.

8. Wave energy converter (100) according to claim 7, wherein the base body of the control element (40) is rotatably mounted, in particular via a shaft, wherein preferably the shaft is rotatable by means of a drive which is preferably controllable by the control unit (60).

9. Wave energy converter (100) according to one of claims 6 to 8, wherein the drive comprises one or more electrical actuators, such as servo motors, and / or mechanical actuators, such as a mechanical coupling device for direct RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025 TI or indirect coupling with the rotor shaft, includes.

10. Wave energy converter (100) according to one of the preceding claims, wherein the wave energy converter (100) has an additional control element for controlling the movement of the wave energy converter (100) in the sea, wherein the additional control element is preferably controllable by the control unit (60) and in particular comprises a drive for adjusting an angle of attack of one or more rotor wings, means for changing the body shape of the additional control element or ballast elements.

11. Method for controlling the motion of a floating wave energy converter (100), wherein the wave energy converter (100) is designed in particular according to one of the preceding claims, comprising the following steps: Acquisition of sensor data of a wave motion using at least one sensor (50); Transmission of sensor data to a control unit (60) of the wave energy converter (100); Control of at least one control element (40), in particular a movable guide surface (41), of the wave energy converter (100) on the basis of the transmitted sensor data by the control unit (60) to generate a movement of the wave energy converter (100) that is phase-shifted with respect to the wave movement.

12. Method according to claim 11, wherein the control unit (60) determines the wave-induced motion excitation of the wave energy converter (100) on the basis of the transmitted sensor data, wherein the control unit (60) further determines an optimal motion of the wave energy converter (100) with regard to the propulsion to be achieved of a rotor unit (10) of the wave energy converter (100), and wherein the control unit (60) controls the control element (40) in such a way that the wave-induced motion excitation is modified to achieve the determined, optimal motion of the wave energy converter (100). RGTH T241419W007718PT Hamburg University of Technology (TUHH) Public corporation 26.11.2025 28 13. Method according to claim 11 or 12, wherein the control unit (60) performs the control of the control element (40) periodically or continuously.

14. Method according to one of claims 11 to 13, wherein the control unit (60) uses the transmitted sensor data and optionally further data, such as dimensions or hydrodynamic parameters of the wave energy converter (100) or empirical data on wave movements, to determine a phase-shifted movement of the wave energy converter (100) relative to the wave movement, in particular an optimal movement of the wave energy converter (100), using simulation models and controls the control element (40) accordingly.

15. Method according to claim 14, wherein the control unit (60) uses the simulation models to make predictions about future wave movements, in particular with regard to the wave cycle following a given time, and uses these predictions to determine the phase-shifted motion.

16. Method according to any one of claims 11 to 15, wherein the control unit (60) performs a calibration step based on sensor data taking into account the forces and / or moments acting on the wave energy converter (100) or components of the wave energy converter (100). RGTH T241419W007718PT

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