Fluid power gearbox and drivetrain for a wave energy converter

1. A power transfer system for a wave energy converter, comprising:

a plurality of hydraulic cylinders comprising a first cluster of input cylinders and a second cluster of output cylinders;

the input cylinders coupled to an underwater structure and configured to receive an input force from a relative motion between a buoy housing and the underwater structure;

the output cylinders configured to transfer an output force to an electric generator;

a hydraulic connection between the input cylinders and the output cylinders; and

wherein the hydraulic connection is configurable to switch a portion of the hydraulic cylinders into and out of the hydraulic connection between the input cylinders and the output cylinders.

2. The power transfer system of claim 1 , further comprising at least one offset cylinder, the at least one offset cylinder configured to offset a weight of the underwater structure.

3. The power transfer system of claim 2 , wherein the offset cylinder is coupled to a gas charged accumulator.

4. The power transfer system of claim 2 , wherein the offset cylinder is pressurized to provide an offset force opposite to the weight of the underwater structure.

5. The power transfer system of claim 2 , wherein the offset cylinder is one of a hydraulic system or pneumatic system.

6. The power transfer system of claim 2 , wherein the offset cylinder is hydraulically isolated from the output cylinders.

7. The power transfer system of claim 2 , wherein the offset cylinder is coupled to a gas charged accumulator with an air tank array, and wherein the air tank array comprises an array of differently sized air tanks.

8. The power transfer system of claim 1 , wherein the input cylinders are arranged mechanically and hydraulically in parallel to each other.

9. The power transfer system of claim 1 , wherein the input cylinders comprise a first group of input cylinders and a second group of input cylinders having a different size than the first group.

10. The power transfer system of claim 1 , wherein the input cylinders are spatially distributed on a structural member, the structural member mechanically coupled to the input cylinders.

11. The power transfer system of claim 1 , further comprising a power dissipation network, and one or more valves to control distribution of power between the electrical generator and the power dissipation network.

12. The power transfer system of claim 11 , wherein the power dissipation network comprises a network of pressure reducing valves configured to dissipate energy by passing fluid through controlled diameter orifices to create heat and then cooling the fluid by passing through a heat exchanger network.

13. A power transfer system for a wave energy converter, comprising:

a plurality of hydraulic cylinders comprising a first cluster of input cylinders and a second cluster of output cylinders;

the input cylinders coupled to an underwater structure and configured to receive an input force from a relative motion between a buoy housing and the underwater structure;

the output cylinders configured to transfer an output force to a linear generator;

a hydraulic connection between the input cylinders and the output cylinders; and

at least one offset cylinder configured to offset a weight of the underwater structure.

14. The power transfer system of claim 13 , wherein the hydraulic connection is configurable to switch a portion of the hydraulic cylinders into and out of the hydraulic connection between the input cylinders and the output cylinders.

15. The power transfer system of claim 13 , wherein the offset cylinder is coupled to a gas charged accumulator with an air tank array, and wherein the accumulator provides elastic absorption of energy with an effective spring constant being a function of an extendable air volume in the air tank array.

16. The power transfer system of claim 13 , wherein the extendable air volume is configured to provide a variable pressure providing an offset force to the weight of the underwater structure.

17. The power transfer system of claim 13 , further comprising a power dissipation network connected in series with the air tank array.

18. The power transfer system of claim 13 , wherein the power dissipation network comprises a network of pressure reducing valves configured to dissipate energy by passing fluid through controlled diameter orifices to create heat and then cooling the fluid by passing through a heat exchanger network.

19. The power transfer system of claim 13 , further comprising a fluid balancing network comprising an external supply of fluid configurable to enter the input cylinders to compensate for fluid loss in the input cylinders.

20. A power transfer system for a wave energy converter, comprising:

a plurality of hydraulic cylinders comprising a first cluster of input cylinders and a second cluster of output cylinders, the input cylinders coupled to an underwater structure and configured to receive an input force from a relative motion between a buoy housing and the underwater structure, the output cylinders configured to transfer an output force to a linear generator;

a hydraulic connection between the input cylinders and the output cylinders, wherein the hydraulic connection is configurable to switch a portion of the hydraulic cylinders into and out of the hydraulic connection between the input cylinders and the output cylinders;

at least one offset cylinder configured to offset a weight of the underwater structure, wherein the offset cylinder is coupled to a gas charged accumulator with an air tank array, and wherein the air tank array comprises an array of differently sized air tanks; and

a power dissipation network with one or more valves to control distribution of power between the electrical generator and the power dissipation network.