Patents Assigned to Ocean Power Technologies, Inc.
  • Patent number: 7965980
    Abstract: A cellular communication system includes an array of buoys disposed in a body of water. Each buoy includes a completer cellular system including a cellular transmission/reception site and associated electrical equipment for processing cellular signals. Each buoy also includes a wave energy converter (WEC) responsive to waves in the body of water for generating electrical energy for powering the associated equipment processing the cellular signals, whereby the cellular system can be continuously operated without any additional power source.
    Type: Grant
    Filed: March 30, 2007
    Date of Patent: June 21, 2011
    Assignee: Ocean Power Technologies, Inc.
    Inventor: Joseph M. Troutman
  • Patent number: 7886680
    Abstract: For reducing the number of components required for mooring (by means of three, 120° spaced apart mooring lines) multiple floating wave energy converters (WECs), a group of six WECs is disposed in a hexagonal pattern with each WEC being disposed at a corner of the hexagon. The WECs are connected to one another by mooring lines extending along sides of the hexagon, each WEC thereby being connected by two, 120° spaced apart mooring lines and with each WEC serving as a mooring point for each of its two adjacent neighbors. A third mooring line for each WEC, spaced 120° from the other two mooring lines, is connected to an auxiliary surface buoy and thence to an anchor.
    Type: Grant
    Filed: February 26, 2007
    Date of Patent: February 15, 2011
    Assignee: Ocean Power Technologies, Inc
    Inventor: Mark R. Draper
  • Patent number: 7877994
    Abstract: The stability and power conversion efficiency of a wave energy converter (WEC) which includes a float, a spar and a power taken device (PTO) connected between the spar and the float is increased by connecting a heave plate to the spar in a very secure manner and by carefully limiting the movement between the float and spar to one direction (i.e., up-down motion). Buoyancy chambers may be attached to the WEC to facilitate its transportation and deployment. The WEC may be formed in sections and assembled at, or close to, the point of deployment.
    Type: Grant
    Filed: April 30, 2007
    Date of Patent: February 1, 2011
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Diana Bull, James Gerber, William Powers
  • Patent number: 7878734
    Abstract: Apparatus embodying the invention include a damping plate attached to the submerged end of a spar-like element floating in a body of water. The spar like element tends to move up and down in a vertical direction in response to passing waves. The damping plate has a pair of oppositely facing surfaces extending transversely to the vertical direction of the movement of the spar-like element and vertical structures (“lips”) mounted on the oppositely facing surfaces for increasing the effective mass of water pushed during movement of the damping plate through the water. Damping plates with lips, as per the invention, may be used in wave energy converters to control the relative motion between the spar-like element and a float to increase the energy produced.
    Type: Grant
    Filed: April 30, 2007
    Date of Patent: February 1, 2011
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Diana Bull, James Gerber, William Powers
  • Patent number: 7781903
    Abstract: A wave energy converter with air compression (WECWAC) includes a cylinder and a piston located within the cylinder dividing the cylinder into an upper chamber and a lower chamber. The cylinder is fixedly attached to a spar whose up/down (heave) motion is restrained. The piston is fixedly attached to, and driven by, a float which moves generally in phase with the waves. Under typical wave conditions the piston functions to compress air within the upper chamber on its up stroke and within the lower chamber on its down stroke, i. e., the system is thus double-acting. In still water, the spar and cylinder combination is designed to drift down into the body of water relative to the piston whereby the size/volume of the upper chamber is decreased (while that of the lower chamber is increased). For small amplitude waves the piston continues to compress air in the upper chamber and this asymmetrical compression continues until the waves reach a predetermine level when “double-action” is resumed.
    Type: Grant
    Filed: May 16, 2007
    Date of Patent: August 24, 2010
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Keith Buffard, Mark Draper, Keith Robert Pullen, Robin Rhodes
  • Patent number: 7658067
    Abstract: In a wave energy converter (WEC) for capturing energy contained in surface waves on large bodies of water, one or both of the floats used in the WEC has an internal spring system including a weight suspended from a spring mechanism having a selectively variable spring constant for allowing vertical oscillations of the weight in response to bobbing motions of the float The mechanical impedance of the system is a function of the oscillations of the weight, hence the system is tunable to selected values of mechanical impedance for optimal coupling with the prevailing waves.
    Type: Grant
    Filed: November 28, 2006
    Date of Patent: February 9, 2010
    Assignee: Ocean Power Technologies, Inc.
    Inventor: James S. Gerber
  • Patent number: 7594780
    Abstract: A damping (or heave) plate comprises a generally flat plate attached, beneath the surface of a sea, and in horizontal orientation, to a structural member subject to being vertically moved in response to passing surface waves. The plate tends to resist vertical movements and has the effect of adding mass to the structure. A vertically extending structure is added to both major surfaces of the heave plate for increasing the volume of water moved by the plate. For minimizing drag forces generally created by use of the damping plate, the vertically extending structure is shaped to include curved hydrodynamic surfaces for minimizing turbulence in the surrounding water.
    Type: Grant
    Filed: May 1, 2007
    Date of Patent: September 29, 2009
    Assignee: Ocean Power Technologies, Inc.
    Inventor: Diana Bull
  • Patent number: 7476137
    Abstract: A wave energy converter (WEC) for converting energy contained in surface waves on a body of water to useful energy comprises two floats movable relative to one another in response to passing surface waves. Both floats comprise expandable outer envelopes which have been expanded into full and firm shape. In one process, expansion is obtained by filling the floats with fluids, for example, air and water. The fluids can be pumped into the floats, or the floats can be mechanically expanded in the presence of the fluids for self filling owing to pressure differentials. In one embodiment, a float envelope can comprise of plurality of end to end connected length sections in nested or telescoped relationship. Expansion is obtained by pulling the telescoped sections out from one and other, for example, by pumping fluids into the telescoped sections.
    Type: Grant
    Filed: August 25, 2006
    Date of Patent: January 13, 2009
    Assignee: Ocean Power Technologies, Inc.
    Inventors: David B. Stewart, James S. Gerber
  • Patent number: 7443046
    Abstract: A wave energy converter (WEC) includes a shell suitable for being placed within a body of water. The shell contains an internal oscillator comprising a “reaction mass” and a spring mechanism coupled between the reaction mass and the shell. The shell and internal oscillator are constructed such that, when placed in a body of water and in response to waves in the body of water, there is relative motion between the shell and the internal oscillator's mass. A power take-off (PTO) device is coupled between the internal oscillator and the shell to convert their relative motion into electric energy. In systems embodying the invention, the spring mechanism is designed such that its displacement or movement is less than the displacement or movement of the reaction mass. The spring mechanism may be any device which enables the reaction mass to undergo a given replacement while its displacement or movement is less than that of the reaction mass. This property enables the size of the WEC to be more readily controlled (e.
    Type: Grant
    Filed: December 1, 2006
    Date of Patent: October 28, 2008
    Assignee: Ocean Power Technologies, Inc
    Inventors: David B. Stewart, James S. Gerber
  • Patent number: 7397152
    Abstract: A linear electric generator (LEG) includes sections of coils of an induction coil assembly (ICA) disposed along a distance d1 and apparatus for passing a permanent magnetic assembly (PMA) of length d2, where d2 is less than d1, along the coils for generating voltages and power in the coils in close proximity to the PMA. Unidirectional conducting elements are connected between the coils and output power lines to couple the voltages developed across excited coils to the output power lines without the unexcited coils loading down or dissipating the voltage developed across the output power lines.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: July 8, 2008
    Assignee: Ocean Power Technologies, Inc.
    Inventors: David B. Stewart, Henry I. Schanzer
  • Patent number: 7362003
    Abstract: In a linear electric generator (LEG) which includes apparatus for passing a permanent magnetic assembly (PMA) along linearly disposed sections of coils of an induction coil assembly (ICA) for generating voltages and power, a switching arrangement for coupling only selected sections of coils of the ICA across the power output lines of the LEG. The selected coil sections include the sections of coils of the ICA in close proximity to the passing PMA. In accordance with different embodiments, the non selected coils of the ICA may be either short circuited or disconnected (open circuited) from the power output lines.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: April 22, 2008
    Assignee: Ocean Power Technologies, Inc.
    Inventors: David B. Stewart, Paul Smalser, Henry I. Schanzer
  • Patent number: 7348764
    Abstract: An electric generator includes multiple coil sections and switches connected to the multiple coil sections for selectively interconnecting the coil sections in series, or in parallel, or in a series-parallel configuration across first and second power terminals for producing a controlled AC voltage across these power terminals. The electric generator, with its multiple coils and interconnecting switches permitting reconfiguration of the coils, enables systems subjected to widely varying conditions and forces, such as a wave energy converter (WEC), to be operated with increased efficiency. The generator may also include multiple windings which can be selectively interconnected into a wye or a delta configuration to also control the output voltage produced by the generator and increase the efficiency of the power conversion system, particularly at low values of voltage.
    Type: Grant
    Filed: July 13, 2006
    Date of Patent: March 25, 2008
    Assignee: Ocean Power Technologies, Inc.
    Inventors: David B. Stewart, Timothy J. Liska
  • Patent number: 7323790
    Abstract: An ocean wave energy converter (WEC) utilizes the relative motion between permanent magnet and induction coil assemblies to generate electricity. The permanent magnet assemblies and induction coil assemblies are separately housed in watertight enclosures, enabling a wide range of wave energy converter configurations, nearly unlimited stroke and obviating the need for a common magnet/coil enclosure with seals. The magnet assemblies are constructed with surface or buried magnets. The wave motion moves a magnet assembly relative to a stationary coil assembly, or vice versa. Either the magnet assembly or the induction coil assembly are made long enough to provide the generation of electricity over a desired operational range of travel. Various means are provided to maintain the spacing (“gap”) between the magnetic and coil assemblies relatively constant.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: January 29, 2008
    Assignee: Ocean Power Technologies, Inc.
    Inventors: George W. Taylor, David B. Stewart
  • Patent number: 7310944
    Abstract: A WEC system embodying the invention includes a column and shell, arranged to move relative to each other, and a lever-like apparatus having an input end and an output end and an intermediate point, between the two ends, the intermediate point being rotatably connected to the column. The input end is connected to the shell and moves at the same velocity and in the same direction as the shell. The output end moves in the opposite direction and at a rate which is a multiple of the shell velocity. The multiple being a function of the ratio of the length of the intermediate point to the output and input ends. In systems embodying the invention, one of two components (a PMA or an ICA) of a linear electric generator may be attached to the shell and the other of the two components may be attached to the output end of the lever-like apparatus to produce high relative velocity between the two components resulting in higher amplitude and higher frequency output voltages.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: December 25, 2007
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Thomas Sabol, David B. Stewart
  • Patent number: 7305823
    Abstract: The invention relates to active impedance matching systems (AIMS) and methods for increasing the efficiency of a wave energy converter (WEC) having a shaft and a shell intended to be placed in a body of water and to move relative to each other in response to forces applied to the WEC by the body of water. The system includes apparatus for: (a) extracting energy from the WEC and producing output electric energy as a function of the movement of the shell (shaft) relative to the shaft (shell): and (b) for selectively imparting energy to one of the shell and shaft for causing an increase in the displacement and velocity (or acceleration) of one of the shell and shaft relative to the other, whereby the net amount of output electrical energy produced is increased. The apparatus for extracting energy and for selectively supplying energy may be implemented using a single device capable of being operated bi-directionally, in terms of both direction and force, or may be implemented by different devices.
    Type: Grant
    Filed: January 13, 2005
    Date of Patent: December 11, 2007
    Assignee: Ocean Power Technologies, Inc
    Inventors: David B. Stewart, James S. Gerber
  • Patent number: 7224077
    Abstract: A power generating system comprises a bluff (non-streamlined) body placed in a fluid stream at ninety degrees to the flow direction for creating a von Karman vortex street behind the body. In the process, feedback forces are generated that excite the bluff body into oscillation. The bluff body oscillatory movements are coupled to and energize a power generator. An impedance matching system is employed for electrically varying the natural frequency characteristics of the bluff body such that, over a relatively wide range of fluid flow velocities, the bluff body oscillates at a resonant frequency of the body for maximum energy transfer from the fluid stream to the bluff body.
    Type: Grant
    Filed: January 13, 2005
    Date of Patent: May 29, 2007
    Assignee: Ocean Power Technologies, Inc.
    Inventor: James J. Allen
  • Patent number: 7168532
    Abstract: A magnetic braking system for inhibiting excessive motion between a float and a column intended to be placed in a body of water; with the float and column moving relative to each other as a function of the waves present in the body of water. The braking system includes a permanent magnetic assembly (PMA) mounted on, and attached to, one of the float and column and a coil assembly (or a conductive plate) mounted on, and attached to, the other one of the float and column. The braking system is mounted such that motion between the float and the column is inhibited when the displacement of the float relative to the column exceeds a predetermined operating range.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: January 30, 2007
    Assignee: Ocean Power Technologies, Inc
    Inventors: David B. Stewart, George W. Taylor
  • Patent number: 7140180
    Abstract: A wave energy converter system comprises two floats; a first being generally flat and heaving up and down in phase with passing surface waves on a body of water, and the second being elongated and heaving up and down out of phase with the passing waves. Preferably, the first float is annular with a central vertical opening therethrough, and the elongated float, with a weighted bottom end, extends vertically through the central opening of the first float. The two floats thus move out of phase with one another, thus providing a relatively large relative motion between the two floats giving rise to highly efficient energy conversion. Each float serves as a “ground” for the other; thus avoiding the need for anchoring the floats to the floor of the body of water.
    Type: Grant
    Filed: January 22, 2004
    Date of Patent: November 28, 2006
    Assignee: Ocean Power Technologies, Inc.
    Inventors: James Gerber, David B. Stewart
  • Patent number: 7141888
    Abstract: A WEC includes a non-circular main central column positioned within a like non-circular central opening of a shell to contain the central column and prevent rotation or twisting of the shell relative to the column. In a particular embodiment, the central column is multi-sided (e.g., a square) and the central opening of the shell is likewise multi-sided (e.g., square). The facing sides of the column and shell are parallel to each other facilitating the layout of the components of a linear electric generator (LEG) between the facing sides and ensuring good magnetic coupling between the components of the LEG over the length of travel of the shell and column.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: November 28, 2006
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Thomas Sabol, David B. Stewart
  • Patent number: 6933623
    Abstract: An elongated cylinder is fully submerged, in vertical orientation, just below the mean water level of, e.g., and ocean, and of a length, dependent upon surface waves of preselected wavelength, such that the top of the cylinder experiences relatively large pressure variations in response to over passing waves while the bottom of the cylinder experiences an almost steady pressure substantially independent of the over passing waves. The pressure differential over the length of the cylinder is used for causing relative movements between the cylinder and adjoining water, and such relative movements are used for driving a piston of an energy converter. The cylinder can be hollow and in fixed location for causing water movements through the cylinder, or the cylinder can move through the water relative to a fixed transducer. In one version of the movable cylinder, the transducer is fixedly mounted on a fixed in place float disposed within the movable cylinder.
    Type: Grant
    Filed: June 7, 2004
    Date of Patent: August 23, 2005
    Assignee: Ocean Power Technologies, Inc.
    Inventors: Charles B. Carroll, Meredith Bell