Patent Publication Number: US-2010117366-A1

Title: Methods and apparatus for power generation

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/904,695, titled “Methods and Apparatus for Power Generation,” filed Mar. 2, 2007, and U.S. Provisional Patent Application No. 60/918,352, titled “Methods and Apparatus for Power Generation,” filed Mar. 16, 2007, both of which are incorporated herein by reference. 
    
    
     ACKNOWLEDGMENT OF GOVERNMENT SUPPORT 
     This invention was made with government support under: contract number DE-FG02-05-ER86257, awarded by the Department of Energy; award number 0300386, awarded by the National Science Foundation; award number NA16RG1039, awarded by the National Oceanic and Atmospheric Administration; and contract number N62473-07-C-4069, awarded by the Department of the Navy. The government has certain rights in the invention. 
    
    
     FIELD 
     The disclosed technologies relate to power generation from wave energy. 
     BACKGROUND 
     Ocean waves are a potential source of energy, for example, for generating electricity. Commonly proposed energy extraction techniques are often based on hydraulic or pneumatic intermediaries that can require high maintenance costs and are often prone to failure. Under operating conditions such as heavy seas, the intermediaries can be damaged by excessive force of the waves. Additionally, at least some devices are relatively expensive to manufacture. 
     SUMMARY 
     An ocean wave energy converter system comprises an armature and a plurality of magnets which move relative to each other in response to ocean waves pushing on a spar and/or float to which the armature and the plurality of magnets are coupled. Components of the system comprise stacked rings and/or radial laminations. The armature can feature a variety of pole tips (also called “shoes”). Various methods can be used to assemble components from radial laminations. Air gaps in wire coils of the armatures can be filled with one or more materials that selectively alter the magnetic permeability of the wire coils. 
     In some embodiments, an apparatus for converting wave motion to electrical power, wherein the system is at least partially immersed in a liquid through which the waves travel, the apparatus comprises: a first component having an overall buoyancy relative to the liquid so as to float in the liquid; a second component movably coupled to the first component, wherein the second component is configured to move relative to the first component in a direction of motion in response to a force from waves that is exerted on the first component; and an electrical generator coupled to the first and second components, the electrical generator comprising an armature and a magnet housing, wherein at least one of the armature and the magnet housing comprises a plurality of laminations that can have major surfaces oriented in the direction of motion. In further embodiments, the armature comprises the plurality of laminations that can have major surfaces oriented generally in the direction of motion. The plurality of laminations can form a plurality of vertically spaced apart projections extending toward the magnet housing, the projections comprising distal and proximate end portions, the distal end portions having distal end surfaces spaced by a gap from the magnet housing, the armature also comprising a backing portion interconnecting proximate end portions of the projections, wherein magnetic flux paths are provided through the distal end portions of the projections and backing portion, the projections defining electrically conductive wire receiving pockets therebetween, and electrical wires positioned at least partially within the wire receiving pockets and coupled to at least one power output. In some embodiments, at least a plurality of the distal ends of the projections are enlarged to increase a volume of said distal end portions and wherein at least a portion of the distal end surface of at least a plurality of distal end portions has a curvature. In further embodiments, at least a plurality of the distal ends of the projections are enlarged to increase a volume of said distal end portions and wherein at least a portion of the distal end surface of at least a plurality of distal end portions is convex. In additional embodiments at least plurality of the distal ends of the projections are enlarged to increase a volume of said distal end portions and wherein at least a plurality of the distal end surfaces comprise a flat central portion parallel to the direction of travel of the magnet housing and a curved peripheral portion. 
     In some cases the plurality of laminations comprising the armature are configured in a plurality of rings stacked generally in the direction of motion. In further cases the plurality of laminations comprising the armature extend in a radial direction and together define an opening through which the magnet housing is inserted. Also, the plurality of laminations comprising the armature can extend in a radial direction and together define a circumference around which the magnet housing is placed. In further embodiments a fill material is positioned between first and second laminations of the plurality of laminations. In additional embodiments at least some of the plurality of laminations are coupled to a component providing one or more apertures for receiving wires in the armature or magnet housing. In some embodiments at least one of the laminations in the plurality of laminations has a non-uniform thickness. For example, at least one of the laminations in the plurality of laminations has a thickness that increases as the lamination extends radially outward. 
     In further embodiments, the plurality of laminations form a plurality of ring segments. In particular embodiments, the magnet housing comprises at least one magnet and at least some of the plurality of laminations that can have major surfaces oriented generally in the direction of motion. At least some of the plurality of laminations comprising the magnet housing can comprise a T-shaped groove. 
     In some embodiments, a heat exchanger is configured to remove heat from the armature. Sometimes one or more coolant passageways are coupled to the heat exchanger. 
     In additional embodiments, an apparatus for converting wave motion to electrical power, wherein the system is at least partially immersed in a liquid through which the waves travel, comprises: a first component having an overall buoyancy relative to the liquid so as to float in the liquid; a second component movably coupled to the first component, wherein the second component is configured to move relative to the first component in a direction of motion in response to a force from waves that is exerted on the first component; and an electrical generator coupled to the first and second components, the electrical generator comprising an armature and a translator, wherein the armature comprises one or more coils, the coils comprising electrically conductive wires with one or more ferrous materials positioned between the wires. In some cases at least a portion of the electrically conductive wires have a round, oval or polygonal cross-section. Sometimes the electrically conductive wires with one or more ferrous materials positioned between the wires comprise one or more wires coated with the one or more ferrous materials before being wound into the coils. Sometimes the electrically conductive wires with one or more ferrous materials positioned between the wires comprise one or more wires wound into the coils with one or more cords comprised of the ferrous materials. In further embodiments the one or more ferrous materials positioned between the wires comprise a plurality of particles oriented in a preferred magnetic flux direction of the particles. 
     In some embodiments a method of making a component for a wave generator armature comprises: winding one or more conductive wires around a support; and filling a gap between at least portions of the one or more wires with one or more materials having a selected magnetic property and comprising a plurality of magnetic particles. In further embodiments filling the gap between the one or more wires with one or more materials having the selected magnetic property comprises coating at least a portion of the one or more wires with the materials having the selected magnetic property. In additional embodiments filling the gap between the one or more wires with one or more materials having the selected magnetic property further comprises heating the wound one or more conductive wires. Sometimes the one or more conductive wires are wound around the support such that the gap is a predetermined gap. Also, filling the gap between the one or more wires with one or more materials having the selected magnetic property can comprise vacuum filling the gap. Sometimes the support is a bobbin and/or a portion of the armature. Sometimes the method further comprises orienting at least some of the magnetic particles using a magnetic field. In some cases filling the gap between at least portions of the one or more wires with one or more materials having the selected magnetic property and comprising the plurality of magnetic particles comprises providing the one or more materials to the gap using a wicking material positioned in the gap. 
     In further embodiments an apparatus for converting wave motion to electrical power, wherein the system is at least partially immersed in a liquid through which the waves travel, comprises: a first component having an overall buoyancy relative to the liquid so as to float in the liquid; a second component movably coupled to the first component, wherein the second component is configured to move relative to the first component in a direction of motion in response to a force from waves that is exerted on the first component; and an electrical generator coupled to the first and second components, the electrical generator comprising at least one component molded from a resin comprising a plurality of magnetic particles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  show views of one embodiment of an ocean wave energy converter system. 
         FIG. 2  shows a vertical sectional view of one embodiment of an ocean wave energy converter system. 
         FIG. 3  shows a vertical sectional view of another embodiment of an ocean wave energy converter system. 
         FIG. 4  shows a vertical sectional view of yet another embodiment of an ocean wave energy converter system 
         FIG. 5  shows a vertical sectional view of the float of the embodiment of  FIG. 4 . 
         FIG. 6  shows an embodiment of an exemplary magnet compartment of  FIGS. 4 and 5 . 
         FIG. 7  shows a vertical sectional view of an embodiment of a magnet compartment and an armature that can be used, for example, in the embodiments of  FIGS. 4 and 5 . 
         FIG. 8  is an enlarged view of a portion of the embodiment of  FIG. 7 . 
         FIG. 9  is an enlarged view of an alternative embodiment of a portion similar to that shown in  FIG. 8 . 
         FIGS. 10-14  show cross-sectional views of various exemplary embodiments of teeth tips that can be used with armature embodiments described herein. 
         FIG. 15  shows a vertical sectional view of an exemplary embodiment of two adjacent armature ring sections. 
         FIG. 16  shows a top plan view of an exemplary embodiment of an armature ring section. 
         FIG. 17A  shows a top plan view of an exemplary embodiment of a plurality of radial laminations. 
         FIG. 17B  shows a side view of an exemplary embodiment of a wire exit guide. 
         FIG. 17C  shows a perspective view of a wire exit guide. 
         FIG. 18  shows a perspective view of a portion of one embodiment of the radial laminations of the embodiment of  FIG. 17A . 
         FIGS. 19-24  show vertical sectional views of various alternative embodiments of the radial laminations of  FIG. 17A . 
         FIG. 25  shows a vertical sectional view of an embodiment of an armature component. 
         FIG. 26  shows a vertical sectional view of an embodiment comprising stacked armature components. 
         FIG. 27  shows a side elevational view of an alternative embodiment comprising radial laminations. 
         FIG. 28  is a vertical sectional view of an embodiment comprising a plurality of laminations held in place by compression rings. 
         FIG. 29  shows a plan view of an exemplary embodiment of a holder configured to receive laminations. 
         FIG. 30  shows an embodiment of a radial lamination for constructing an exemplary armature. 
         FIG. 31  shows an embodiment of a lamination for constructing an exemplary backiron section. 
         FIG. 32  shows a perspective view of an embodiment of an exemplary magnet housing component. 
         FIG. 33  shows a perspective view of one embodiment of a bobbin. 
         FIG. 34  shows a flowchart of an exemplary embodiment of a method for filling air voids in a wire coil. 
         FIG. 35  shows embodiments of exemplary cross-sections of wires that can be used in making a relatively low air gap coil. 
         FIGS. 36A-36C  depict an exemplary embodiment of an ocean wave energy converter system. 
         FIG. 37  shows a vertical sectional view of an exemplary embodiment of an armature and a field. 
         FIG. 38  shows a close-up vertical sectional view of an exemplary embodiment of a wire coil in  FIG. 37 . 
         FIG. 39  shows a cross-sectional view of an exemplary embodiment of a wire encased at least in part by a fill portion designed to provide a square cross-section. 
         FIG. 40  shows a cross-sectional view of an exemplary embodiment of a wire coil. 
         FIG. 41  shows a perspective view of a slice of the wire coil of  FIG. 40 . 
         FIG. 42  shows a cross-sectional view of an exemplary embodiment of a wire wrapped in a plurality of fill threads. 
         FIG. 43  shows a cross-sectional view of an exemplary embodiment of a wire coil. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed below are embodiments of wave power generation system technologies and/or related technologies. The embodiments should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed methods, apparatus, and equivalents thereof, alone and in various combinations and subcombinations with one another. The disclosed technologies are not limited to any specific aspect or feature, or combination thereof, nor do the disclosed methods and apparatus require that any one or more specific advantages be present or problems be solved. 
     As used in this application and in the claims, the singular forms “a,” “an” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” The phrase “and/or” can mean “and,” “or” and “one or more of” the elements described in the sentence. Moreover, unless the context dictates otherwise, the term “coupled” means physically connected or electrically or electromagnetically connected or linked and includes both direct connections or direct links and indirect connections or indirect links through one or more intermediate elements. Embodiments described herein are exemplary embodiments of the disclosed technologies unless clearly stated otherwise. 
     Although the operations of some of the disclosed methods and apparatus are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially can in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods and apparatus can be used in conjunction with other methods and apparatus. 
     At least some technologies are described herein as applying to transverse flux power generators. However, unless explicitly stated otherwise, the technologies described herein also apply to longitudinal flux power generators. Also, unless explicitly stated otherwise, technologies described herein with respect to electric generators can also be applied to electric motors. 
       FIG. 1A  shows a side view of one embodiment of a buoy generator system (i.e., an ocean wave energy converter system)  100 . The buoy generator system  100  comprises an elongated spar  110  and a float  120 . In various embodiments, spar  110  has a cross section that is round, square, or a number of other shapes, can be at least partially hollow, and can be constructed of a material that can withstand ocean conditions for a relatively long period of time, such as PVC or composite material. The float  120  is coupled to the spar  110  for movement relative to the spar. Desirably the float  120  encircles spar  110  at least in part (e.g., partially or entirely), and can be comprised of any number of buoyant materials. System  100  can further comprise a ballast weight  130  and a tether  140 .  FIG. 1A  shows tether  140  as being connected to ballast weight  130 , but it can also be connected to other parts of system  100 , e.g., to spar  110 . The remote end of tether  140  is connected to a mooring system  142 , which can be any system or arrangement that allows the system  100  to maintain a relatively constant geographic position. For example, the mooring system could comprise a sea-floor mooring, a weight (such as an anchor) or pilings. A power output such as an electric cable  144  carries electricity from the system  100  to another location, e.g., a shore-based electric facility  146 . The top end of spar  110  can be sealed by, for example, a cap  150  to protect its contents from the elements. Spar  110  is desirably configured such that it (with its contents) is approximately neutrally buoyant. System  100  can also comprise a wave deflector or wave motion resistor, such as a wave plate  145 , which can be attached or coupled to spar  110 , usually at a right angle to spar  110 . However, wave plate  145  can also be attached at other angles. Wave plate  145  can provide a dampening force to improve a desirable relative linear motion of float  120  and spar  110 .  FIG. 1B  shows a top view of the system  100 . 
     Generally, generator system  100  can be moored offshore in an area where waves are common. As waves propagate past system  100 , the waves move float  120  generally upwardly and downwardly relative to and along spar  110 . System  100  converts at least some of the relative motion provided by the waves to electricity. 
     It should be noted that, although the motion of float  120  to spar  110  can be described and is often described in the application as “relative linear motion,” other types of relative motion can also be used. For example, if spar  110  is curved, float  120  can move along spar  110  in an arcuate motion. Relative linear sliding motion is a particularly desirable approach. 
     Cap  150  and plate  145  prevent total separation of float  120  and spar  110  in this example. 
       FIG. 2  shows a vertical sectional view of one embodiment  200  of an ocean wave energy converter system (also referred to herein as a “transverse flux power generator”), taken along the line  2 - 2  indicated in  FIG. 1B . In this embodiment, the spar  120  comprises a translator (e.g., a field) with a plurality of magnets, such as magnets  210 , interspersed with spacers  220 , such as metal disks or supports. In some embodiments the magnets  210  comprise rare earth magnets, for example, NdFeB magnets (e.g., NdFeB-35, NdFeB-38H). The float  120  can comprise an armature  230 , which is described in more detail below. 
       FIG. 3  shows a vertical sectional view of one embodiment  300  of an ocean wave energy converter system, taken along the line  3 - 3  indicated in  FIG. 1A . In this embodiment, the float comprises a translator with one or more magnets (such as magnets  310 ) interspersed with one or more supports (e.g., metal plates or rings, such as rings  320 ). The spar  110  can comprise an armature  330 , which, in some embodiments, is supported by one or more brackets (not shown) which fasten the armature  330  to the spar  110 , or by other supports such as rods (not shown). 
       FIG. 4  shows a vertical sectional view of an additional embodiment  400  of an ocean wave energy converter system. In this embodiment, a float  420  comprises a magnet compartment  460  (an example of which is described in more detail below). The exemplary spar  410  comprises an armature  430  and upper and lower end caps  450 ,  452 .  FIG. 5  shows the float  420  without the spar  410 . 
     Generally, in systems such as embodiments  100 ,  200 ,  300  and  400 , as the float is moved up and down relative to the spar, an armature and magnets move relative to each other. As the armature moves through the magnetic fields, currents are generated in one or more wire coils of the armature. 
       FIG. 6  shows the magnet compartment  460  of  FIGS. 4 and 5  in more detail. The exemplary compartment  460  comprises backiron sections  610 ,  612 . Respective inner surfaces  614 ,  616  of the backiron sections  610 ,  612  are, in this example, at least partially covered with one or more magnet rows or tiers, such as rows  620 ,  622 . In the example of  FIG. 6 , the tiers are stacked vertically. Each magnet row  620 ,  622  in this example is annular and comprises one or more magnets such as magnets  630 . In at least some embodiments, one or more of the magnets  630  are curved, e.g., in order to better fit against a curved backiron section. Generally, magnets in the rows  620 ,  622  are arranged such that adjacent rows have opposite magnetic polarities. For example, in some embodiments magnets of the row  620  are N-polarity, while magnets of the row  622  are S-polarity. In various embodiments, the magnets  630  can be held in place using one or more retainers  640  (made of aluminum, for example) and/or additional fastening devices (e.g., screws or rivets). In particular embodiments, one or more end retainers, such as ring portions  650 ,  652 , can also be used to hold at least some magnets  630  in place. 
       FIG. 7  shows a vertical sectional view of an armature  700  and a magnet compartment  710  that can be used with ocean wave energy converter systems described herein. The armature  700  comprises a plurality of teeth, such as teeth  720 ,  722 . In various embodiments, wire coils can be positioned between teeth  720 ,  722 , although such coils are not shown in  FIG. 7 . In various embodiments, the armature  700  comprises one or more ring sections, such as ring sections  730 ,  732 . Plates  740 ,  742  can be used to compress the ring sections and reduce movement of the ring sections  730 ,  732  relative to one another. The plates  740 ,  742  can be interconnected and drawn together by bolts or other fasteners to compress the ring sections  730 ,  732  to provide mechanical and structural integrity. In some embodiments the plates  740 ,  742  can be comprised of non-magnetic and non-conductive material, and the material can be chosen to prevent or reduce eddy current loss. 
       FIG. 8  is a close-up vertical sectional view of the portion of the armature indicated in  FIG. 7 . In this view, a plurality of wire coils  810 ,  812  are shown positioned in wire receiving pockets between and defined at least in part by the teeth  820 ,  822 ,  824 . In the depicted embodiment, the magnet compartment  710  comprises a backiron  840  and one or more magnets  850 ,  852 ,  854  and one or more retainers  860 ,  862 . 
       FIG. 9  shows a close-up vertical sectional view of another embodiment of an armature portion similar to the portion indicated in  FIG. 7 . In this embodiment, magnets  910 ,  912 ,  914  comprise flared tips (e.g., tips  920 ,  922  on magnet  912 ) positioned at the side of the magnet that faces the armature. In such embodiments, one or more retainers  930  can be used to hold the magnets  910 ,  912 ,  914  in place. 
     Returning briefly to  FIG. 8 , armature teeth such as teeth  820 ,  822 ,  824  have various shapes in various embodiments.  FIGS. 10-14  depict cross-section views of various embodiments of exemplary teeth tips that can be used with armature embodiments described herein. In some embodiments, the tips comprise a plurality of surfaces that generally diverge to a common surface (e.g., a common flat surface, a common curved surface). For example,  FIG. 10  shows an embodiment of a “flared” tip  1000  comprising inclined surfaces  1002 ,  1004  extending to a generally flat surface  1010 . In further embodiments, the tips comprise a plurality of surfaces that generally diverge and then converge. In some cases such tips converge to a common surface. For example,  FIG. 11  shows an embodiment of a tip  1100  comprising inclined surfaces  1102 ,  1104 ,  1106 ,  1108  that lead to a generally flat surface  1110 . As an example of a further embodiment,  FIG. 12  shows a tip  1200  comprising inclined surfaces  1202 ,  1204  leading to a convex, generally rounded surface  1206  having a radius R. In some embodiments, R can be based at least in part on the pole pitch of the magnets in the magnet compartment. In at least this context, “pole pitch” can be defined as the distance between the north and south poles of the magnets positioned opposite the tip. According to some embodiments, 
     
       
         
           
             R 
             = 
             
               polepitch 
               π 
             
           
         
       
     
     For example, given a pole pitch of 72 mm, R=22.9 mm. 
       FIG. 13  shows an additional embodiment of a tip  1300 , which comprises inclined surfaces  1302 ,  1304  leading to respective curved surfaces  1306 ,  1308 . The curved surfaces are also adjacent a generally flat surface  1310 .  FIG. 14  shows an additional embodiment of a tip  1400  comprising inclined surfaces  1402 ,  1404 ,  1406 ,  1408 . In at least some embodiments, armature tooth shoe designs can be selected to change variations in magnetic flux in an armature during operation (e.g., as the poles move relative to the magnets). A change in flux can produce a proportional change in a generator&#39;s output voltage. Generally, the output voltage waveform for a given cyclic flux variation can take a variety of shapes. For example, the waveform can take a sinusoidal or trapezoidal shape, or a combination of these shapes. In at least some embodiments a selected output voltage waveform can be achieved using a particular tooth shoe design and/or magnet pole shaping. 
     In further embodiments, armature tooth shoe designs can also affect a net sum of forces along an axis of motion in the generator. The combined sums of magnetic forces along the axis of motion are commonly known as “cogging forces.” A selected tooth shoe design and a selected armature length can reduce cogging forces. In at least some embodiments, for a given armature length, a fractional pole pitch can be determined to fit a given number of slots and teeth. In at least some embodiments, for a three-phase machine, a fractional pole pitch α cp  can be determined by the equation 
     
       
         
           
             
               a 
               cp 
             
             = 
             
               polepitch 
               
                 3 
                  
                 
                   τ 
                   s 
                 
               
             
           
         
       
     
     where τ s  is the distance between the centers of adjacent armature teeth, sometimes known as the “slot length.” The distance τ s  comprises a slot width and a tooth width, and in at least some embodiments one or both of these widths are selected to avoid magnetic flux saturation in the teeth. 
     In some embodiments the design can comprise an even number of slots and an odd number of teeth. As explained below with respect to  FIG. 30 , in some embodiments one or more end teeth on an armature (with respect to the direction of relative motion of the armature) can be shaped for reduced cogging given a selected tooth width. 
     One exemplary method for determining an armature length that can minimize cogging forces (for a configuration where the armature is shorter than an associated translator, e.g., where the armature is shorter than the total number of magnetic pole lengths in the translator) is: 
       armature length=[(poles−1)×polepitch]+magnetic pole length 
     In the above equation, poles is the number of magnetic poles in the armature and magnetic pole length is the length of a magnet pole as measured along the axis of motion. This equation applies to designs with a consistent reluctance (e.g., no teeth) in the active region of the armature, such as an air gap wound machine with selected permeability. An exemplary embodiment of such a machine appears in  FIG. 37 , which shows a vertical sectional view of a portion of an embodiment  3700  where an armature  3710  comprises a backiron  3720  and a plurality of wire coils  3730 ,  3732 . A field  3740  (e.g., a magnet housing) comprises a plurality of magnets  3742 ,  3744  and poles  3746 ,  3748 . The wire coils  3730 ,  3732  are positioned in a gap  3750  between the backiron  3720  and the field  3740 . 
     In some embodiments, an effective magnetic pole length and an effective armature length can be determined according to the amount of magnet pole shaping (e.g., by varying the magnetic pole length) and end tooth tapering, respectively. In particular embodiments a calculated armature length can be varied to create and effective armature length by altering the shape of armature end teeth  3760 ,  3762 . The effective armature length can differ from the calculated armature length by approximately ±1, 5, 10 or 20 percent of the pole pitch value. 
     As shown in  FIG. 15 , in some embodiments tooth sections  1532 ,  1534  on two adjacent armature ring sections  1510 ,  1520  can form a tip  1530 . Other plural section tips can also be employed. For example, any one of the tips described above in connection with  FIGS. 10-14  can be a plural section tip. The embodiment of  FIG. 15  also shows exemplary ring sections  1510 ,  1520  with wire passageways or conduits  1540 ,  1542 . The conduits provide exit points, e.g., for a wire  1544  from a wire coil  1546  positioned in the ring section  1520 . A backiron  1550 , coupled to the ring sections  1510 ,  1520  can be used as a heat sink for the ring sections. In some embodiments, the backiron  1550  can be provided with one or more cooling passageways or conduits, such as a vertically extending conduit  1552 , perpendicular to conduits  1540 ,  1542 . Conduit  1552  can be used for carrying cooling fluid or a refrigerant (e.g., water, sea water, or other coolant). The conduit  1552  can be coupled to a heat exchanger  1560  and a pump (not shown). 
     In particular embodiments, an armature ring section (e.g., ring sections  720 ,  730  in  FIG. 7 ) can comprise one or more ring sub-sections.  FIG. 16  shows a plan view of a ring section  1600  that is similar to the ring sections  720 ,  730 . In the depicted embodiment, the ring section  1600  is comprised of six subsections  1610 ,  1620 ,  1630 ,  1640 ,  1650 ,  1660 . Further embodiments can comprise more or fewer subsections. The subsections define an aperture  1670 . Further embodiments of the ring section  1600  comprise one or more features for promoting alignment of vertically adjacent ring sections, such as interlocking ridges (not shown) and/or one or more pins (e.g., a pin  1680 ) and corresponding pin receiving holes. 
     Although the armature ring section embodiments shown in  FIGS. 7-9  show ring sections with one tooth, in further embodiments an armature ring section has two or more teeth. In particular embodiments, the armature can be comprised of only one ring section that has all teeth for the armature. 
     Components for ocean wave energy converter systems described herein can be made using a variety of methods and can have a variety of compositions. In some embodiments, one or more components (e.g., an armature and/or a magnet compartment) can comprise a plurality of radial laminations. As used herein, “radial laminations” refers to laminations that can have major surfaces oriented generally in (but not necessarily perpendicular to) the direction of motion of the component comprised of the laminations. These laminations can have planar, parallel major opposed surfaces.  FIG. 17A  shows a plan view of a component  1700  comprising a plurality of radial laminations, such as laminations  1710 ,  1720 ,  1730 . In at least some embodiments, the laminations define an opening  1740 , such as an opening having a circular or other shaped cross-section. A wire exit guide  1760  can be positioned near the opening  1740  and between radial laminations  1770 ,  1780  to provide an entrance and/or exit route for wires going in and out of the component  1700 .  FIG. 17B  shows a side view of the wire exit guide  1760 , which in the depicted embodiment features upper holes  1762  and lower holes  1764  for receiving wires entering or exiting the component  1700 .  FIG. 17C  shows a perspective view of the wire exit guide  1760 . The laminations  1710 ,  1720 ,  1730  generally comprise a thin ferro-magnetic material with an insulation (usually a thin insulation) on the outer surface. Laminations can be made of, for example, Fe, Fe—Si, Superpermalloy; or other materials (e.g., C4 M19 Silicon Lamination Steel, available from Proto Laminations, Inc.). In various embodiments, the lamination material can be chosen based on one or more considerations such as permeability, insulation, environment temperature, magnetic saturation, and/or structural design considerations. In at least some embodiments, a component constructed of radial laminations maintains a constant cross-section of ferro-magnetic material, allowing for a constant flux density and optimized ferro-magnetic material utilization. 
     In further embodiments one or more filling materials can be placed between some or all of the laminations, e.g., to provide support for the laminations. For example, a filling material  1750  can be positioned between the laminations  1720 ,  1730  (and also between other laminations). Exemplary filling materials include epoxies, polymers and/or thermosetting resins. Generally, the filling material  1750  can be selected such that the spaces between the laminations are relatively light. For example, in some embodiments the filling material  1750  weighs about one fourth of what an equivalent volume of iron fill would weigh. Thus, the filling material  1750  can be used to reduce the weight of the finished component  1700 . 
       FIG. 18  shows a perspective view of an embodiment of the component  1700  with an approximately 90-degree portion of the laminations removed. This view shows that, in at least some embodiments, the laminations can be configured to provide a cavity  1810 . The cavity  1810  can be generally annular extending through adjacent laminations along any portion of the 360 degrees of the component. The cavity  1810  can be an interior cavity spaced from the peripheral edges of the laminations. In particular embodiments, the component  1700  is used to form an armature, and the cavity  1810  holds a wire coil for the armature, as shown below. In some such embodiments, the opening  1740  is available to receive a spar comprising a magnet compartment. 
       FIGS. 19-24  show vertical sectional views of various exemplary embodiments of the component  1700 , as taken along a line corresponding to the line A-A of  FIG. 17 .  FIG. 19  depicts an embodiment where laminations, such as a lamination  1910 , form an annular cavity  1920  bounded on four sides by the individual laminations.  FIG. 20  depicts an embodiment where laminations, such as laminations  2010 ,  2012 , define an upper cavity  2020  and/or a lower cavity  2022 , as well as one or more pole tips  2030 .  FIG. 21  depicts an embodiment where laminations  2110 ,  2112  form an annular cavity  2120  bounded on three sides by the individual laminations. In the embodiment of  FIG. 21 , the laminations  2110 ,  2112  comprise partial pole tips (e.g., partial tips  2130 ,  2132 ,  2134 ,  2136 ) which can be used to form plural section tips (see, e.g.,  FIG. 15  and the above corresponding discussion). The laminations of the embodiment of  FIG. 21  can be used to form a plural section tip having a form, for example, similar to that of tip  1000  in  FIG. 10 .  FIGS. 22  comprises laminations  2210 ,  2212 , which comprise partial pole tips such as partial tip  2220 . The laminations of  FIG. 22  can be used to form a plural section tip having a form, for example, similar to that of tip  1200  in  FIG. 12 .  FIG. 23  shows an embodiment with laminations having partial tips  2320 ,  2322 ,  2324 ,  2326  that can be used to form a plural section tip having a form similar to that of tip  1400  of  FIG. 14 .  FIG. 24  shows laminations  2410 ,  2412  which are similar to those of  FIG. 20 , but which comprise pole tips  2420 ,  2422  similar to those of tip  1000  of  FIG. 10 . 
       FIG. 25  shows a vertical sectional view of an armature component  2500  (using the lamination embodiment of  FIG. 21 ), further comprising a wire coil  2510  positioned in a cavity  2520 . The wire coil  2510  is positioned such that a central longitudinally extending opening is available to receive a spar. Although at least some of the embodiments of  FIGS. 17-24  are shown as lending themselves to forming an armature with teeth on the inner circumference of the armature, further embodiments can be configured to form an armature with teeth on the outer circumference of the armature. 
     Generally, pluralities of components comprising radial laminations, such as those shown in  FIGS. 17-25 , can be stacked on each other. For example,  FIG. 26  shows two components  2602 ,  2604  (like the components of  FIG. 24 ) stacked together so as to form a cavity  2610 , which in the depicted embodiment contains a wire coil  2620 . 
       FIG. 27  shows a side elevational view of an embodiment similar to the component  1700  of  FIG. 17 . Radial laminations such as laminations  2710 ,  2712  are desirably parallel or approximately parallel to each other. In at least some cases, this configuration reduces losses due to eddy currents. In some embodiments, the laminations  2710 ,  2712  are skewed or oriented at an angle θ to a longitudinal axis  2720  extending through the center of the component. For example, when the component  1700  is used in conjunction with embodiments of ocean wave energy converter systems described herein, the axis  2720  can be the axis along which the float and the spar move relative to each other. In certain embodiments, θ is equal to or approximately equal to zero degrees, while in further embodiments θ=±1, 5, 10 or 20 degrees. In various embodiments, all of these are included in the phrase “oriented generally in the direction of motion.” A particularly desirable angle is zero degrees, which in at least some embodiments results in a lowest induced eddy current loss. Other angles can have mechanical and/or structural purposes and can sometimes reduce eddy current loss. Other embodiments can comprise laminations oriented at other angles and/or one or more angles. 
     Components, such as the component  1700 , can be assembled using a variety of methods and devices. For example,  FIG. 28  shows a vertical sectional view of a plurality of laminations (e.g., laminations  2810 ,  2812 ) inserted between and held in place by compression rings  2820 ,  2822 . The compression rings can be any suitable material, with fiberglass being a specific example. In further embodiments, a lamination can be spaced apart from adjacent laminations by one or more shims, spacers and/or fillers. 
     As another example,  FIG. 29  shows a plan view of a holder  2920  (e.g., a slotted spool or other device) configured to receive laminations  2910 ,  2912 ,  2914 . The holder  2920  can retain the laminations  2910 ,  2912 ,  2914  until they are fixed (e.g., using a filler or other device or substance). Alternatively, the holder  2920  can remain in place and can include a central aperture to receive a spar.  FIG. 29  also shows an embodiment of laminations  2910 ,  2912 ,  2914  having a non-uniform thickness. In the depicted embodiment, the thickness of the laminations increases as the laminations extend radially outward. 
       FIG. 30  shows an embodiment of an exemplary radial lamination  3000  for constructing an armature. The lamination was designed for an embodiment where the armature comprises only one ring of laminations, although in further embodiments the lamination  3000  (or similar laminations) can be shorter and used to form an armature ring with a plurality of stacked rings used to form an armature. Teeth (e.g., teeth  3010 ,  3012 ) forming portions of the lamination  3000  comprise flared tips with curved surfaces (e.g., curved surface  3020 ). The base of slot-forming portions of the lamination between the teeth can comprise rounded corners (e.g., corner  3030 ) which in at least some cases minimize the effects of corner flux saturation. A top tooth  3040  forming portion and a bottom tooth  3042  forming portions comprise tapered edges  3044 ,  3046  (e.g., about 45 degrees), which can reduce cogging effects. Rear tapered edges  3050 ,  3052  can serve as mechanical stops when, for example, the lamination  3000  is inserted into a ring assembly structure such as that shown in  FIG. 28 . 
       FIG. 31  shows an embodiment of an exemplary backiron lamination  3100  that can be used for constructing a backiron section (e.g., the backiron sections  610 ,  612  of  FIG. 6 ). The lamination  3100  comprises a plurality of grooves  3110  configured to receive one or more retainers  640 , as described above. In some embodiments, the grooves  3110  are T-shaped so as to avoid interference with a magnetic flux path in the backiron section  610 ,  612 . In at least some embodiments, the T-shaped grooves help avoid narrowing the flux path in the backiron lamination with respect to magnet pole length. Generally, a flux path narrower than the magnet pole length results in flux concentration, which can in turn lead to flux saturation. Abrupt changes in the flux path can create undesired areas of flux saturation in the backiron and also promote flux leakage and fringing at the magnet edges. 
     Returning briefly to  FIG. 6 , in some embodiments the backiron components  610 ,  612  of the magnet compartment  460  can be comprised at least partially of a plurality of radial laminations, as explained in more detail below. Also,  FIG. 32  shows an embodiment of a magnet housing component  3200 , which can be used as part of a spar or buoy, for example. The exemplary component  3200  comprises a magnet  3210  and one or more radial lamination end pieces  3220 ,  3222 . In some embodiments, a plurality of magnets are placed vertically end-to-end, with one or more radial lamination end pieces between the magnets. In some embodiments, the end pieces  3220 ,  3222  can act as flux concentrating pole pieces by providing flux paths above and/or below a given magnet. 
     In further embodiments, the radial lamination end pieces are comprised of non-magnetic materials. These materials can be, for example, aluminum and/or fiberglass. The end pieces can provide mechanical and structural integrity. They preferably have a low relative permeability, which can make them less likely to interfere with electrical or magnetic aspects of the system. 
     In at least some embodiments wire coils, such as those shown in  FIGS. 8 ,  15 ,  25  and  26 , can be fabricated by winding wire around a bobbin, such as one made of a plastic (e.g., Delrin). The bobbin-supported wire coil can be placed between armature teeth (e.g., between the teeth  820 ,  822  of  FIG. 8 ), which in at least some cases provides assembly time savings.  FIG. 33  shows a perspective view of one embodiment of an exemplary bobbin  3300 . In some embodiments a bobbin is keyed or pinned to provide for a desired rotary position of the bobbin during installation into the armature. In some embodiments a binder, such as an epoxy or other resin, is used during the bobbin winding process to form a solid winding structure. In further embodiments the bobbin can be removed after a wire coil is formed on the bobbin. 
     In further embodiments a bobbin can comprise an exit aperture or groove  3310  through which a wire from a wire coil can pass. In particular embodiments, the aperture  3310  can comprise a connector socket coupled to a connector plug that is integrated with another armature component such as a ring. Such embodiments can reduce undesired air gaps in the armature by allowing for a relatively small hole that provides a path through the armature to the bobbin. In some embodiments, a wire coil wound on the bobbin  3310  is one wire high and comprises a plurality of turns in the radial direction. When used in an armature similar to those described in this application, this configuration allows for a maximum number of phases. 
     In additional embodiments, a wire coil is initially wound directly between teeth of an armature rather than on a separate support structure such as a bobbin. 
       FIG. 38  shows a close-up vertical sectional view of the wire coil  3730  of  FIG. 37 , which in the depicted embodiment shows round cross-sections of a plurality of wires  3810 . Generally, wires wound into a coil such as the wire coil  3730  have a plurality of gaps (e.g., gap  3820 ) between adjacent wires. In a wire coil wound of round wires, generally a fill factor of about 80% wire is achieved. When gaps such as gap  3820  are filled with non-magnetic materials (e.g., air), these gaps can inhibit the magnetic flux path in the coil. In the embodiment of  FIG. 38 , gaps between the wires  3810  are filled at least in part by a plurality of particles  3830  suspended in a carrier substance  3840 , in order to increase the magnetic permeability of spaces between the wires  3810 . The particles  3830  comprise one or more magnetic materials such as, but not limited to, iron, iron alloys, Permalloy, nickel alloys, chromium alloys, cobalt alloys, and other materials with a generally high magnetic permeability. In some embodiments the particles  3830  have an average diameter of about 50-100 microns, but smaller or larger particles can also be used. In a particular embodiment, particles of about 325 mesh (a diameter of about 44 microns) are used. In further embodiments the particles  3830  can comprise particles of multiple sizes. The carrier substance  3840  can comprise, for example, an epoxy, plastic and/or resin. The concentration of the particles  3830  in the carrier substance  3840  can range from about 1% to about 100%. Varying the concentration of ferrous material in the fill can alter one or more magnetic properties of the space occupied by the wire coil and the fill. For example, the relative permeability can be altered. 
     In at least some embodiments the particles in the carrier substance  3840  are non-spherical. For example, the particle  3832  has a generally elongated shape. Such an elongated particle  3832  can be oriented in one or more particular directions. In some embodiments, the particle  3832  can be aligned with a magnetic field to which the armature is subjected (e.g., perpendicular to the direction in which the wires of the coil  3730  are wound). Such oriented elongated particles can result in a magnetic permeability that is directionally dependent. In some cases, this could be used to direct flux in a preferred direction. 
     In further embodiments, one or more generator components (e.g., an armature and/or a magnet compartment) can be molded out of one or more carrier substances containing a plurality of magnetic particles, such as those described above. 
       FIG. 34  shows a flowchart of an embodiment of a method  3400  for filling air voids in a wire coil. In a method act  3410 , one or more wires are wound around a support (e.g., a bobbin, an armature component, or other support). In particular embodiments the one or more wires are wound relatively loosely to create gaps in the wire coil. The gaps can be, for example, about 20% to about 90% of the fill volume of the wire coil. In some embodiments, one or more gaps between wires are created by placing material between wires, e.g., as the wire coil is being wound. For example, turning briefly to  FIG. 38 , a piece of material  3850  created a gap among some wires of the coil  3730 . Such oriented elongated particles can result in a magnetic permeability that is directionally dependent. In at least some cases, this could be used to direct flux in a preferred direction. Returning to  FIG. 34 , in a method act  3420  one or more gaps between the windings are filled. In some embodiments the gaps are filled by applying a coating (e.g., as was discussed above with respect to  FIGS. 37 and 38 ) with the fill to the wire as it is wound onto the support. The coating can be applied during winding of the coil. For example, the coating can be applied using a brush or a syringe applicator. In further embodiments, the fill is applied to a partially or fully wound coil using vacuum filling. In embodiments where gaps between wires are created using one or more pieces of material, as described above, properties of the material can be used to fill the gaps. For example, in some embodiments the material has wicking properties (e.g., in the case fabrics such as cotton or fiberglass) which can draw a coating into at least some of the gaps. 
     In embodiments where the fill comprises elongated particles (such as  3832  described above with respect to  FIG. 38 ), in a method act  3430  the elongated particles can be arranged in a specific orientation. This can be accomplished, for example, by applying a magnetic field to the fill before the fill has set. 
     In some cases, in a method act  3440 , a wire coil is heated to better distribute the fill through the coil. At least some of these embodiments can provide for a homogenous distribution of ferrous material in the wound coils of an armature. 
     In further embodiments, a wire can be manufactured with a configuration designed to achieve a higher fill volume. For example, in some embodiments a wire coil is made of one or more wires having a cross-section allowing for a relatively high fill volume.  FIG. 35  shows exemplary cross-sections of wires  3510 ,  3520 ,  3530  that can be used to make a relatively low air gap coil (e.g., triangular, rounded square, trapezoidal, diamond, hexagonal). Generally, wires having polygonal cross-sections (e.g., as shown in  FIG. 35 ) can be wound more closely than wires with round cross-sections, thus reducing air gaps in the coil. However, wires having round cross-sections  3502  or oval cross-sections  3540  can also be used. For additional embodiments, a wire can be manufactured with a fill designed to give the cross-section of the wire a selected shape. For example,  FIG. 39  shows the circular cross-section of a wire  3910  encased at least in part by a fill portion  3920  designed to provide a square cross-section.  FIG. 40  shows the cross-section of an exemplary wire coil  4000  made with wire similar to that of  FIG. 39 . As shown in  FIG. 40 , fill portions such as portion  4020  can reduce gaps between the wire  4010  and its neighboring wires.  FIG. 41  shows a perspective view of a slice of the wire coil  4000 . 
     In still further embodiments, a wire can be at least partially wrapped in a fill material. For example,  FIG. 42  shows a cross-sectional view of a wire  4210  that is wrapped in a plurality of fill threads  4220 ,  4222 ,  4224 ,  4226 .  FIG. 43  shows a cross-sectional view of an exemplary wire coil  4300  made using wire similar to that of  FIG. 42 . 
     In some cases, wire embodiments such as those shown in  FIGS. 39-43  are manufactured with one or more exterior orientation marks to aid in winding the wire. Also the embodiments of  FIGS. 39-43  can also be heated, as described above with respect to the method act  3440 . 
       FIG. 36A  depicts an ocean wave energy converter system  3600 , which comprises a float  3620  and two or more spars  3610 . The particular embodiment shown features three spars  3610  surrounded by float  3620 . Spars  3610  are reinforced from above by support structure  3612 , but in other embodiments a support structure on the underside of system  3600  can be added. In another embodiment no support structure is present. Spars  3610  and float  3620  together comprise systems similar to those described previously in this application. Similar to other embodiments described above, ballast weights  3630  and wave plates  3645  can be attached to spars  3610 , and the spars can be held in place using tethers  3640 . 
       FIG. 36B  provides a top view of system  3600 , showing float  3620 , spars  3610  and support structure  3612 . The top ends of the spars  3610  can have caps as in other disclosed embodiments, although they are not shown in  FIGS. 36A  or B.  FIG. 36C  is a bottom view of system  3600 , showing float  3620 , ballast weights  3630  and wave plates  3645 . 
     In view of the many possible embodiments to which the principles of the disclosed technologies may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.