Electric device and method

• US 20040251692A1
• Filed: 01/07/2003
• Published: 12/16/2004
• Est. Priority Date: 01/10/2002
• Status: Active Grant

• Current Assignee: Seabased AB
• Original Assignee: Seabased AB
• Inventors: Leijon, Mats, Bernhoff, Hans
• Granted Patent: US 7,164,212 B2
• Time in Patent Office: Days
• US Class Current: 290/42
• CPC Class Codes: F03B 13/1885 and the wom is tied to the rem
• CPC Class Codes: F05B 2220/707 of the linear type
• CPC Class Codes: Y02E 10/30 Energy from the sea, e.g. using wave energy or salinity gradient

Abstract

The present invention relates to a wave-power unit having a floating body (3) which is connected by a connection means (4) to the rotor (7) of an electric linear generator (5). The stator (6) is anchored in the sea bed (1). In accordance with the invention the rotor (7) is permanently magnetic and the stator (6) comprises winding forming a plurality of poles distributed in the direction of movement of the rotor. The invention also relates to a wave-power plant composed of a number of wave-power units in accordance with the invention. The invention also relates to the use of the claimed wave-power unit, a method of generating electric energy, a system of components for the manufacture of a linear generator for a wave-power unit in accordance with the invention, and to a method of manufacturing such a linear generator.

Claims

1. A wave-power unit for the production of electric power comprising a floating body (3) and an electric linear generator (5) whose rotor (7) by connection means is connected to the floating body (3) and whose stator (6) is arranged to be anchored in the bed (1) of a sea/lake, characterized in that the rotor (7) is permanently magnetic and in that the stator (6) comprises a winding forming a plurality of poles distributed in the direction of movement of the rotor (7).

2. A wave-power unit as claimed in claim 1, characterized in that the rotor is vertically oriented.

3. A wave-power unit as claimed in claim 1 or claim 2, characterized in that the rotor comprises a plurality of permanent magnets distributed in the direction of movement of the rotor.

4. A wave-power unit as claimed in any one of claims 1-3, characterized in that the distance between the poles seen in the direction of movement of the rotor (7) is less than 50 mm, preferably less than 10 mm.

5. A wave-power unit as claimed in any one of claims 1-4, characterized in that the stator (6) comprises a plurality of laminated stacks (6a-6d) distributed evenly around the rotor.

6. A wave-power unit as claimed in claim 5, characterized in that the rotor (7) is shaped as a regular polygon and in that the number of laminated stacks (6a-6d) is equal to the number of sides of the polygon.

7. A wave-power unit as claimed in claim 5 or claim 6, characterized in that each laminated stack (6a-6d) is composed of a plurality of modules arranged one after the other in the direction of movement of the rotor (7).

8. A wave-power unit as claimed in any one of claims 5-7, characterized in that the rotor comprises a plurality of permanent magnets distributed around its circumference and so arranged that in an optional cross section of the rotor a permanent magnet faces towards each laminated stack.

9. A wave-power unit as claimed in claim 8 characterized in that the rotor comprises a rotor body on which the magnets are mounted.

10. A wave-power unit as claimed in any one of claims 1-9, characterized in that the length of the rotor (7) and that of the stator (6) differ from each other.

11. A wave-power unit as claimed in claim 10, characterized in that the rotor is longer than the stator.

12. A wave-power unit as claimed in any one of claims 1-11, characterized in that one or more guide elements (16) is/are arranged to control the rotor (7).

13. A wave-power unit as claimed in any one of claims 1-12, characterized in that at least a part of the connection means (4) is flexible.

14. A wave-power unit as claimed in claim 13, characterized in that the connection means comprises a cable, wire or chain.

15. A wave-power unit as claimed in claim 13 or claim 14, characterized in that it comprises spring means (11) arranged to exert a force on the rotor.

16. A wave-power unit as claimed in claim 15, characterized in that the spring rate of the spring means is adjustable.

17. A wave-power unit as claimed in any one of claims 1-16, characterized in that the length of the connection means is adjustable.

18. A wave-power unit as claimed in any one of claims 1-17, characterized in that it comprises a gear mechanism that produces a gear ratio between the movement of the floating body and that of the rotor.

19. A wave-power unit as claimed in claim 18, characterized in that the gear mechanism is arranged where the connection means joins the rotor.

20. A wave-power unit as claimed in any one of claims 1-19, characterized in that the linear generator is secured to a base plate arranged to rest on the bed of the sea/lake.

21. A wave-power unit as claimed in any one of claims 1-20, characterized in that the stator is supported by a stand secured to the base plate and so designed that it forms a central free space of sufficient cross-sectional dimensions to permit the rotor to enter the space, which space is at least as high as the rotor is long.

22. A wave-power unit as claimed in any one of claims 1-21, characterized in that the linear generator is enclosed in a watertight housing.

23. A wave-power unit as claimed in claim 22, characterized in that the connection means extends into the housing and in that the lead-through is provided with a seal or bellows.

24. A wave-power unit as claimed in claim 22, characterized in that the housing is filled with a liquid.

25. A wave-power unit as claimed in any one of claims 18-24, characterized in that the base plate, stand and/or housing is/are primarily made of concrete.

26. A wave-power unit as claimed in any one of claims 1-20, characterized in that the stator is at least partially embedded in a solid material and/or that the rotor is at least partially embedded in a solid material, said material being preferably concrete.

27. A wave-power unit as claimed in any one of claims 1-26, characterized in that the rotor is hollow and is provided with permanent magnets directed both outwardly and inwardly and in that laminated stacks are arranged on both the outside and the inside of the rotor.

28. A wave-power unit as claimed in any one of claims 1-27, characterized in that the floating body is connected by the connection means to a the rotor of each of a plurality of linear generators.

29. A wave-power unit as claimed in any one of claims 1-28, characterized in that the stator windings are connected to a rectifier, which rectifier is preferably arranged close to the linear generator below the surface of the water, if applicable preferably inside the housing.

30. A wave-power unit as claimed in any one of claims 1-29, characterized in that the generator is arranged to produce a voltage of varying frequency.

31. A wave-power unit as claimed in any one of claims 1-30, characterized in that the generator is arranged to supply multiphase current.

32. A wave-power plant comprising a plurality of wave-power units (20a-20g) as claimed in any one of claims 1-31 characterized in that the stator winding of each wave-power unit is connected via a rectifier (22) to an inverter (23) which is common to a plurality of wave-power units (20a-20g), which inverter is arranged to supply energy to an electric supply network (25).

33. A wave-power plant as claimed in claim 32, characterized in that at least one electric switchgear station is connected to the wave-power unit, which switchgear station comprises a watertight container enclosing switchgear components, which container is anchored in the sea bed.

34. A wave-power plant as claimed in claim 33, characterized in that a plurality of switchgear stations are connected to the wave-power unit, each switchgear station being connected to a number of wave-power units.

35. A wave-power plant as claimed in claim 33 or claim 34, characterized in that each switchgear station is connected to a receiving station arranged on land.

36. A wave-power plant as claimed in any one of claims 33-35, characterized in that at least one of the switchgear stations comprises a step-up transformer and/or an intermediate station comprising a step-up transformer.

37. A wave-power plant as claimed in any one of claims 33-36, characterized in that at least one of the switchgear stations and/or the intermediate station comprises a converter.

38. A wave-power plant as claimed in any one of claims 33-37, characterized in that at least one of the switchgear stations and/or the intermediate station comprises means for storing energy.

39. A wave-power plant as claimed in any one of claims 33-38, characterized in that at least one of the switchgear stations and/or the intermediate station comprises filtering means for filtering outgoing and/or incoming current and voltage.

40. A wave-power plant as claimed in any one of claims 33-39, characterized in that at least one of the switchgear stations and/or the intermediate station is filled with non-corrosive, buffered liquid.

41. A wave-power plant as claimed in any one of claims 32-40, characterized in that a filter and/or a transformer is/are arranged after the inverter.

42. A wave-power plant as claimed in claim 41, characterized in that the inverter, filter and/or transformer is/are arranged on land.

43. A wave-power plant as claimed in any one of claims 32-42, characterized in that each wave-power unit is connected to the inverter via a cable arranged on or close to the sea or lake bed.

44. The use of a wave-power unit as claimed in any one of claims 1-31 or a wave-power plant as claimed in any one of claims 32-43 for generating electric power.

46. A method as claimed in claim 45, characterized in that the method is utilized while making use of a wave-power unit as claimed in any one of claims 1-31.

54. A system of components for manufacturing a linear generator for a wave-power unit as claimed in any one of claims 1-31, characterized in that the components comprise a plurality of stator modules of standard, uniform type, which stator modules are suitable to be arranged in an optional number in a line one after the other in the direction of movement of the rotor and/or suitable to be arranged in an optional number side by side distributed around the centre line of the rotor.

55. A system as claimed in claim 54, characterized in that the components comprise a plurality of permanent magnets of standard, uniform type, which permanent magnets are suitable to be attached in an optional number to a rotor body in line one after the other in the direction of movement of the rotor and/or suitable to be secured in an optional number to the rotor body side by side distributed around the centre line of the rotor, and which permanent magnets are suited to the stator modules.

56. A method of manufacturing a linear generator for a wave-power unit as claimed in any one of claims 1-31, characterized in that the stator is manufactured from stator modules of standard, uniform type, that the stator is constructed from a plurality of laminated stacks arranged evenly distributed side by side around the centre line of the rotor and in that each laminated stack is composed of one or more stator modules arranged in line one after the other in the direction of movement of the rotor.

57. A method as claimed in claim 56, characterized in that the rotor is manufactured from permanent magnets of standard, uniform type, in that a plurality of permanent magnets are attached to a rotor body, evenly distributed side by side around the centre line of the rotor and in that one or more permanent magnets is/are secured in line one after the other in the direction of movement of the rotor.

45. A method of generating electric power by connecting a floating body to the rotor of an electric linear generator and anchoring the stator of the generator in the sea or lake bed, characterized in that the rotor is permanently magnetic and in that the stator is provided with a winding forming a plurality of poles distributed in the direction of movement of the rotor.

47. A method as claimed in either of claims 45-46, characterized in that the stator is placed directly on the sea or lake bed or on a base plate resting on the bed, and in that a recess is made in the sea bed centrally below the generator, the depth of the recess corresponding to the length of the rotor.

48. A method as claimed in any one of claims 45-47, characterized in that the energy generated is conducted to a switchgear station, the components of which are arranged in a watertight container, which container is anchored in the sea bed.

49. A method as claimed in claim 48, characterized in that the switchgear station is enclosed in a receiving station arranged on land.

50. A method as claimed in claim 49, characterized in that a plurality of switchgear stations are connected to a common intermediate station, which intermediate station is connected to the receiving station.

51. A method as claimed in any one of claims 48-50, characterized in that at least one of the switchgear stations and/or the intermediate station is arranged below the surface of the water, preferably close to the sea bed.

52. A method as claimed in any one of claims 48-51, characterized in that voltage generated is step-up transformed in at least one of the. switchgear stations and/or the intermediate station.

53. A method as claimed in any one of claims 48-52, characterized in that the outgoing voltage from at east one of the switchgear stations and/or from the intermediate station is alternating voltage.