Two-Body Wave Energy Converter Dynamic Control
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Solution Overview
Problem
Single-body wave energy converters are not well-suited for deep water environments due to the difficulty in providing deep water piling or mooring structures capable of withstanding hydrodynamic forces, and they can interfere with seabed ecosystems near shore, while two-body converters struggle to maximize relative motion between bodies for efficient energy conversion.
Innovation Solution
A two-body wave energy converter design with a primary and secondary floating body, connected by a visco-elastic connection and a generator, dynamically controls the relative motion of the bodies by varying the mass of a slug body, the stiffness or damping characteristics of the visco-elastic connection, and the load damping of the generator to optimize energy capture and conversion, even in changing wave conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single body systems are used with piling or mooring structures, then the floating body can react against a stationary opposing body to convert kinetic energy, but it is difficult to provide deep water piling or mooring structures capable of withstanding hydrodynamic forces and they can interfere with seabed ecosystems
Solution Approach 1:
The invention extracts the stationary opposing body (piling or mooring structure) from the system by using a second floating body instead. This second body floats freely on the water surface without requiring deep water piling or mooring structures, thereby eliminating the need for such structures while still providing the necessary reaction force for energy conversion.
Solution Approach 2:
The second floating body acts as a counterweight or reaction mass that provides the necessary opposing force for the primary floating body. Instead of using a fixed mooring structure anchored to the seabed, the system uses the buoyancy and inertia of the second floating body to create the reaction force needed for kinetic energy conversion.
2Adaptability or versatility
If two body converters are used with a second floating body, then deep water deployment is enabled without piling structures, but the relative motion between bodies is not maximized for efficient energy conversion
Solution Approach 1:
The invention makes the system dynamic by allowing both the primary and secondary floating bodies to move freely on the water surface. The second floating body is not fixed but can oscillate and move in response to wave forces, enabling the system to adapt to changing wave conditions and maximize relative motion between the two bodies for efficient energy conversion.
Solution Approach 2:
The system changes the operational parameters of the floating bodies by allowing variable motion amplitudes and frequencies in response to wave conditions. The masses, buoyancy characteristics, and damping properties of both bodies are optimized to enhance phase separation and maximize relative motion under varying wave environments, thereby improving energy conversion efficiency.
3Device complexity
If the second floating body remains relatively stationary to emulate single body systems, then the system is simpler to control, but the driving force to the generator and electrical energy output are reduced
Solution Approach 1:
The invention makes the second floating body dynamic rather than stationary, allowing it to oscillate and move in response to wave forces. This dynamic behavior increases the relative motion between the primary and secondary bodies, thereby enhancing the driving force to the generator and increasing electrical energy output while maintaining manageable control through passive dynamic response.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the phase separation and amplitude of oscillations between the bodies, increasing the driving force to the generator and thus the electrical energy output, while minimizing damage during extreme waves and avoiding interference with seabed ecosystems.
Implementation Method 1
connected by a visco-elastic connection and a generator, dynamically controls the relative motion of the bodies
Implementation Method 2
The kinetic energy produced as the floating body oscillates relative to the stationary opposing body is converted to electrical energy by a generator coupled between the two bodies
Implementation Method 3
Wave energy (i.e. the energy of periodically oscillating waves on an ocean, sea, lake or other large body of water) can be converted to electrical energy by using the waves' buoyant force to cause a floating body to oscillate
Data Source
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AI summary
A wave energy converter (100, 200 or 300) has a primary body (102, 202 or 302) interconnected to a secondary body (104, 204 or 304) such that the bodies may oscillate longitudinally relative to one another. A slug mass (106, 208 or 308) is visco-elastically connected to the primary body. The slug mass has effective mass, stiffness and damping characteristics. A generator (108, 216 or 316) is drivingly connected between the primary and secondary bodies. The generator has a load damping characteristic. At least one of the aforementioned characteristics is dynamically controllable, allowing the bodies' longitudinal motion to be varied in response to wave motion changes of the wave environment in which the wave energy converter is deployed, to maintain out-of-phase oscillation of the bodies, thus increasing the driving force imparted to the generator and thereby increasing the generator's electrical energy output.