Apparatus for converting wave energy into electric power

• US 20090008942A1
• Filed: 10/13/2005
• Published: 01/08/2009
• Est. Priority Date: 10/15/2004
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique
• Original Assignee: Centre National De La Recherche Scientifique
• Inventors: Babarit, Aurelien, Duclos, Gaelle, Clement, Alain
• Granted Patent: US 7,989,975 B2
• Time in Patent Office: Days
• US Class Current: 290/53
• CPC Class Codes: F03B 13/20 wherein both members , i.e. wom and rem are movable relative to the sea bed or shore
• CPC Class Codes: F05B 2250/44 one element moving inside another one, e.g. wave-operated member (wom) moving inside another member (rem)
• CPC Class Codes: Y02E 10/30 Energy from the sea, e.g. using wave energy or salinity gradient

Abstract

The invention concerns an apparatus for converting wave energy into electric power, comprising a closed floating element (1) and a mass forming element (2), the mass forming element (2) being arranged inside the floating element (1) and mounted mobile relative to the floating element (1), the mass forming element (2) being adapted to be set in relative motion with respect to the floating element (1) under the action of the waves on the floating element (1). The invention is characterized in that it also comprises locking means (13) adapted to lock the movement of the mass forming element (2) and control means adapted to control the locking means (13) for selectively locking or releasing the mass element (2) so as to amplify the movement of the mass forming element (2) by constant adaptation to the dynamics of the apparatus to successive waves.

Claims

1. An appliance for the conversion of wave energy into electrical energy, including a closed float element (1) and a mass-forming element (2), with the mass-forming element (2) being placed inside the float element (1) and mounted to be mobile in relation to the float element (1), with the mass-forming element (2) being designed to be driven into relative movement in relation to the float element (1) under the action of the waves on the float element (1), characterized in that it also includes locking means (13, 50-59) designed to lock the movement of the mass-forming element (2), and control means designed to control the locking means (13, 50-59) so as to selectively lock or release the mass-forming element (2) in order to amplify the movement of the mass-forming element (2) by continuously adapting the dynamic of the appliance to the successive waves.

2. An appliance according to claim 1, in which the control means are designed to control the locking means (13, 50-59) so that they lock the mass-forming element (2) when the latter reaches a relative speed that is relatively zero in relation to the float element (1).

3. An appliance according to one of the preceding claims, in which the control means are designed to control the locking means (13, 50-59) so that they lock the mass-forming element (2) for a locked period that is calculated as a function of the movement of the float element (1).

4. An appliance according to one of the preceding claims, in which the mass-forming element (2) is free to rotate about a rotation axis, with the movement of the mass-forming element (2) not being limited by a limiting device.

5. An appliance according to one of the preceding claims, in which the mass-forming element (2) has a form of revolution with an axis of revolution (4), and the mass-forming element (2) is able to rotate upon in relation to the float element (1) about this axis of revolution.

6. An appliance according to claim 5, in which the mass-forming element (2) has a generally cylindrical shape and is able to rotate upon itself in relation to the float element (1) about the axis of the cylinder.

7. An appliance according to one of claims 4 to 6, in which the mass-forming element has a centre of gravity that is eccentric in relation to the axis of revolution.

8. An appliance according to one of claims 4 to 7, including a power recovery device that has at least one rotating wheel in contact with the mass-forming element (2)

9. An appliance according to claim 8, in which the power recovery device includes a generator connected to the rotating wheel.

10. An appliance according to one of claims 4 to 7, including a power recovery device that includes a multiplicity of windings (81) and a multiplicity of magnets (82) positioned on the mass-forming element (2) and on the float element (1) in such a manner that when the mass-forming element (2) is driven in rotation in relation to the float element (1), an electric current is generated in the windings (81).

11. An appliance according to one of the preceding claims, in which the float element includes a top part (60) surmounting a bottom part (70), with the bottom part (70) containing the mass-forming element.

12. An appliance according to claim 11, in which the bottom part (70) has a generally flat cylindrical shape.

13. An appliance according to either of claim 11 or 12, in which the top part (60) is of flared shape, which broadens toward the top.

14. An appliance according to claim 13, in which the top part (60) is of flared shape, which broadens toward the top below the waterline, and a profiled shape without a superstructure above the waterline so as to minimise the damaging action of the breaking waves in extreme sea conditions.

15. An appliance according to one of the preceding claims, in which the float element (1) is profiled in such a manner that when the appliance is immersed in water and moored by a single line, it is naturally orientated in relation to the main propagation direction of the waves so as to obtain maximum driving of the mass-forming element (2).

16. An appliance according to claim (15), including a mass-forming element (2) mounted to rotate upon a rotation axis (A) in relation to the float element (1), with the appliance being orientated naturally so that the rotation axis (A) is substantially perpendicular to the main propagation direction of the waves.

17. An appliance according to one of the preceding claims, including general mass-forming elements, mounted to be mobile in relation to the float element, with each mass-forming element being designed to be driven into movement in relation to the float element under the action of the waves on the float element, and locking means associated with each mass-forming element, with the control means being designed to control the locking means so as to selectively lock or release each of the mass-forming elements.

18. A method for the conversion of wave energy into electrical energy from an appliance that includes a closed float element (1) and a mass-forming element (2), with the mass-forming element (2) being placed inside the float element (1) and mounted to be mobile in relation to the float element (1), with the mass-forming element (2) being designed to be driven into movement in relation to the float element (1) under the action of the waves on the float element (1), characterised in that it includes stages that consist of controlling locking means (13, 50-59) designed to lock the movement of the mass-forming element (2) by means of control means so as to selectively lock or release the mass-forming element (2) in order to amplify the movement of the mass forming element (2) by continuously adapting the dynamic of the appliance to the successive waves.

19. A method according to claim 18, including stages in which:

measuring means regularly transmit, to processing means, data that include parameter values relating to the movements of the float element and of the mass-forming element,

the processing means determine the values of the dominant driving frequency of the waves at a later time, as a function of the measured parameter values,

the control means control the locking means so that they lock the mass-forming element at the instant when the mass-forming element reaches zero relative speed in relation to the float element,

the processing means determine an optimum period ({circumflex over (θ

)}) for locking of the mass-forming element, as a function of the values of the dominant drive frequency of the waves,

the control means command the locking means to release the mass-forming element when the timing counter has reached the optimum period ({circumflex over (θ

)}).

20. A method according to claim 19, in which, in order to determine the optimum period ({circumflex over (θ

)}) for locking the mass-forming element, the processing means look up a pre-established table containing locking period values ({circumflex over (θ

)}) as a function of the value of the driving frequency of the waves at a later time.

21. A method according to claim 20, in which the locking period values ({circumflex over (θ

)}) have been determined for a regular swell and for the appliance concerned.