U.S. patent application number 11/998816 was filed with the patent office on 2008-11-20 for magnetic vertical axis wind turbine.
Invention is credited to Thomas J. Priest-Brown, James A. Rowan.
Application Number | 20080286112 11/998816 |
Document ID | / |
Family ID | 37996528 |
Filed Date | 2008-11-20 |
United States Patent
Application |
20080286112 |
Kind Code |
A1 |
Rowan; James A. ; et
al. |
November 20, 2008 |
Magnetic vertical axis wind turbine
Abstract
A lift and drag-based vertical axis wind turbine in which the
vertical axis and foils mounted thereon are magnetically levitated
above the turbine's base, thereby reducing friction within the
system. The foils or vanes are three-dimensionally shaped about the
vertical axis so as to resemble the billowed sail of a sailing ship
and capture wind through 360 degrees of rotation under any wind
condition. The system has an axial flux alternator using variable
resistance coils which can be individually and selectively turned
on or off depending on wind conditions and electrical draw
requirements. The coils can also be used to produce mechanical drag
on the system as desired to brake the turbine in high wind
conditions or for maintenance. The system may be programmed to
assess whether electricity generated by the system can be or should
be transmitted to a public grid or stored locally on a chargeable
battery system.
Inventors: |
Rowan; James A.; (Fonthill,
CA) ; Priest-Brown; Thomas J.; (Burlington,
CA) |
Correspondence
Address: |
ROBERT C. CURFISS
19826 SUNDANCE DRIVE
HUMBLE
TX
77346
US
|
Family ID: |
37996528 |
Appl. No.: |
11/998816 |
Filed: |
November 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11262915 |
Oct 31, 2005 |
7303369 |
|
|
11998816 |
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Current U.S.
Class: |
416/244R ;
416/223R |
Current CPC
Class: |
F05B 2220/7066 20130101;
F05B 2220/7068 20130101; F03D 80/70 20160501; Y10S 416/06 20130101;
F05B 2240/51 20130101; Y02E 10/74 20130101; F03D 3/062
20130101 |
Class at
Publication: |
416/244.R ;
416/223.R |
International
Class: |
F03D 3/06 20060101
F03D003/06; F01D 5/14 20060101 F01D005/14 |
Claims
1. A vertical axis wind turbine comprising: a. a base defined about
a vertical axis and having a first magnet mounted on said base; b.
a rotor defined about a vertical axis and having a second magnet
mounted on said rotor; and c. a plurality of vanes mounted on said
rotor, d. wherein said rotor is positioned adjacent said base so
that said first magnet of said base is disposed adjacent said
second magnet of said rotor thereby causing said rotor to be
rotatingly suspended above said base.
2. The wind turbine of claim 1, wherein said rotor includes an
axially positioned aperture, said turbine further comprising a
center rod axially attached to said base and extending through said
aperture of said rotor.
3. The wind turbine of claim 2, wherein said rotor further
comprises a hollow shaft concentrically attached to said rotor over
said aperture, such that said rod extends through said shaft.
4. The wind turbine of claim 3, wherein said vanes are attached to
said shaft.
5. The wind turbine of claim 4, wherein at least one of said vanes
is triangular in shape.
6. The wind turbine of claim 5, wherein said vane is defined by an
inner edge, an outer edge and a lower edge, wherein said inner edge
intersects said outer edge at a first point, said inner edge
intersects said lower edge at a second point and said outer edge
intersects said lower edge at a third point.
7. The wind turbine of claim 6, wherein said inner edge is defined
along an axis and said outer edge curves around the axis.
8. The wind turbine of claim 6, wherein said outer edge is
curvilinear.
9. The wind turbine of claim 6, wherein said lower edge is
curvilinear.
10. The wind turbine of claim 6 wherein rotor is substantially
circular and is defined by an outer perimeter and an inner
perimeter terminating adjacent said aperture, wherein said third
point of said vane is attached to said rotor adjacent said outer
perimeter and said second point of said vane attaches to said rotor
adjacent said inner perimeter.
11. The wind turbine of claim 1, wherein said base is characterized
by an outer perimeter and said rotor is characterized by an outer
perimeter and further comprising: a. a plurality of magnetic
transformers attached at the outer perimeter of said base; and b. a
plurality of magnets attached at the outer perimeter of said
rotor.
12. A wind turbine comprising: a. a base defined about an axis; b.
a rotor defined about an axis and coaxially mounted on said base;
c. a plurality of triangular shaped vanes mounted on said rotor,
wherein said vanes are characterized by an inner edge, an outer
edge and a lower edge, wherein said inner edge intersects said
outer edge at a first point, said inner edge intersects said lower
edge at a second point and said outer edge intersects said lower
edge at a third point and wherein said inner edge is defined along
an axis and said outer edge curves around the axis.
13. The wind turbine of claim 12, wherein said the axis of said
vanes are parallel to the axis of said rotor.
14. A vertical axis wind turbine comprising: a. a base defined
about a vertical axis and having a first magnet mounted on said
base, wherein said base is characterized by an outer perimeter; b.
a rotor defined about a vertical axis and having a second magnet
mounted on said rotor, wherein said rotor is characterized by an
outer perimeter and wherein said rotor is positioned adjacent said
base so that said first magnet of said base is disposed adjacent
said second magnet of said rotor thereby causing said rotor to be
rotatingly suspended above said base; c. a plurality of triangular
shaped vanes mounted on said rotor, wherein said vanes are
characterized by an inner edge, an outer edge and a lower edge,
wherein said inner edge intersects said outer edge at a first
point, said inner edge intersects said lower edge at a second point
and said outer edge intersects said lower edge at a third point and
wherein said inner edge is defined along an axis and said outer
edge curves around the axis; d. a plurality of magnetic
transformers attached at the outer perimeter of said base; and e. a
plurality of magnets attached at the outer perimeter of said
rotor.
15. A method of operating a vertical axis wind turbine, said method
comprising the steps of: a. providing a vertical axis wind turbine
having a rotor concentrically positioned over a base, wherein a
plurality of magnets is positioned around the periphery of said
rotor and a plurality of magnetic transformers is positioned around
the periphery of said base; b. providing a controller to control
the activation of said magnetic transformers; and c. using said
controller to selectively activate and deactivate said magnetic
transformers to control the drag between the rotor and the base.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/262,915 filed on Oct. 31, 2005. Priority
under that application is claimed and that application is
incorporated by reference into the subject application.
BACKGROUND OF INVENTION
[0002] The present invention relates generally to wind turbines,
and more particular to low resistance, vertical axis wind turbines
that utilize a unique airfoil design to enhance rotation in winds
from a single direction, multiple directions including winds
blowing from directly above, and cyclonic winds.
[0003] In recent years there has been a dramatic increase in the
demand for energy in all forms including fuels and electricity for
heating, lighting, transportation and manufacturing processes due
to the world's population rapidly increasing, the supply and
price-volatility problems of using petroleum and other "fossil"
fuels for energy, and the accelerated technological development of
large sectors of the world. Despite the construction of
hydroelectric facilities and the development of fossil fuel
resources at a rapid rate, it has become increasingly evident these
efforts are inadequate to keep pace with the growing population's
demand. First, fossil fuels such as oil and natural gas are
increasingly becoming higher in cost and their availability is
limited. Second, the hope that nuclear power would soon lead to a
rapid solution of the energy dilemma has been tempered by
environmental and safety concerns.
[0004] In the face of these growing demands and the resulting
research in many fields of energy, wind energy has once again
become the focus of such research, in part because the source of
such energy, namely wind, is readily available to every country in
the world in virtually unlimited quantities, subject only to use of
wind turbines or other devices capable of converting the motive
force of the wind into energy in a form usable by modern
technologies. The interest in the development and harnessing of
wind energy for use in homes and factories in the form of
electricity is rising as with the rising costs and prices of
traditional fossil fuel energy. Wind energy is also desirable
because it can be converted to practical use without environmental
contamination or chemical air pollution concerns.
[0005] One method of converting wind energy to practical use is
through the use of a wind turbine. Traditional wind turbines,
including what is historically known as a windmill, are horizontal
axis wind turbines (HAWTs), wherein blades or vanes are secured to
a horizontally supported shaft. As wind impinges on the blades, the
horizontal shaft rotates, which rotation can then be translated
into electric energy. Typically, the horizontal shaft itself pivots
about a horizontal axis (hence the "horizontal axis wind turbine"
name) so that the shaft and blades can pivot with the prevailing
wind direction so that the shaft and blades can change their
orientation as the winds change direction. One drawback to HAWTs is
the inefficiencies caused by friction arising from the supported
shaft. HAWT turbines utilize bearings for turning, and such
bearings can wear out and need replacement. An additional drawback
to HAWT turbines is that only the prevailing wind from a single
direction can be "harnessed" at any one time to generate energy, so
that the HAWT design can be inefficient or the blades and
associated gearing can be damaged in changeable or turbulent winds,
due to torque. Another drawback is that HAWT wind turbines may not
turn or may need mechanical assistance to begin turning, if the
wind speed is too low to counter the inertia of the HAWT rotator
and bearings.
[0006] More recent developments in wind turbine technology have
focused on vertical axis wind turbines (VAWTs), wherein a foil or
vane is mounted on a vertically supported axis. Because of their
vertical axes of rotation, VAWTs do not require alignment with the
direction from which the wind is blowing. Prior art VAWTs include
drag-based designs that move by being pushed by the wind, and
lift-based designs which move from lift that is developed by the
vanes. These prior art designs suffer inefficiencies due to drag
during part of the rotation, which is a consequence of the vane
shapes and gearing.
[0007] Various attempts have been made in the prior art to develop
a method for utilizing wind energy by use of a vertical axis type
windmill/wind-turbine. For example, U.S. Pat. No. 226,357 issued
Apr. 6, 1880, describes a drag-based vertical axis windmill design.
This patent teaches a windmill design that utilizes flat "fans"
mounted pivotally on a support structure to catch wind and cause
the support structure to rotate. As the fans orbit the vertical
axis, they pivot between a downwind orientation, presenting a broad
area that catches the wind, and an upwind orientation in which a
narrower profile passes before the wind in order to create less
drag. One drawback to this design is that the flat fans are not
very aerodynamic in design and thus operation is rough and slow,
with the fans being pulled out of position by centrifugal force.
The fans provide drive only intermittently during a somewhat small
portion of each rotation. Further, upright structural bars at the
outermost ends of the fans obstruct airflow and prevent the system
from achieving rotor speeds faster than wind speed.
[0008] Another illustration of the development of VAWT's is found
in U.S. Pat. No. 2,038,467 issued on Apr. 21, 1936, wherein there
is described a vertical axis drag-based windmill design that
employs flat "vanes" on a rotating frame. The two-phase vanes are
balanced on the vertical axis so that they pivot about 170 degrees
between a high-drag position downwind and a low-drag position
upwind. The windmill exhibits drag rotation over 180 degrees of
each revolution, but vane interference of the upwind vane over the
downwind vane in its wind shadow reduces overall effectiveness.
Thus, the effective transference of force occurs over less than 180
degrees.
[0009] Other VAWT prior art attempts utilizing a lift-based design.
For example, U.S. Pat. No. 4,383,801 issued May 17, 1983, discloses
a lift-based VAWT that includes vertically arranged vanes mounted
pivotally on a rotating base. As the vanes catch the wind and move
the support, they orbit the vertical axis. A wind-vane-controlled
pitch adjustment continually orients the airfoils relative to the
wind direction. The device detects wind direction by means of a
vane and positions the controlling pitch flange accordingly. One
drawback to this patent is that the positioning of the airfoils is
truly effective only in the directly windward and directly leeward
positions, using crosswind lift force in both cases.
[0010] Another example of a lift-based VAWT is U.S. Pat. No.
6,688,842 issued Feb. 10, 2004. In this patent, a VAWT with "free
flying" airfoils is taught, wherein the airfoils are
self-positioning according to the local dynamic conditions to which
they are subjected, thereby creating a condition of equilibrium in
order to make the "engine" more efficient. More specifically, the
patent teaches a vertical axis wind engine with a rotor mounted on
a base for rotation about a vertical axis. One or more airfoil(s)
is mounted on the rotor so that it is free to pivot between preset
first and second limits of pivotal movement (e.g., set by stop
mechanisms). That arrangement enables the airfoil to align
according to the wind as it orbits the vertical axis, thereby
achieving better conversion of wind energy to useable rotational
energy by combining lift and drag characteristics at low speeds and
shifting to lift-only characteristics at rotor speeds approaching
or exceeding local wind speed. Wind forces and
armature-constraining action establish airfoil positions. The
airfoils rotate freely through an arc of approximately 90 degrees,
bounded by stop mechanisms. The span of travel is from a radial
line along the mounting arm (radially aligned relative to the
vertical axis) to a perpendicular position (tangentially aligned
relative to the vertical axis). This prior art design allows for
each airfoil to set its own instantaneous angle and to adjust to
conditions of relative wind, wind shift, and so forth occurring
outside and within the wind engine, "without external adjustments
or mechanisms, wind vanes, centrifugal governors, or other
controlling devices." Individual airfoils adjust to local
conditions based on changes of rotor speed, turbulence, true
relative wind, and other factors affecting each of them
independently. A drawback to this design, however, is that the
efficiency is limited because the airfoils rotate through only
about a 90 degree arc (out of a possible 360 degrees) and are
constrained by stops.
[0011] A further drawback to the various VAWTs of the prior art is
similar to those inefficiencies found in the HAWTs, namely that
there is a relatively large amount of weight carried by the
bearings that support vertically rotating component of the VAWTs.
In addition to the loss of energy resulting from the friction
between the relative components, this leads to the need to replace
bearings on a regular basis.
[0012] Notwithstanding the foregoing, in recent years various
electricity generating utilities have conceived of the need to
promote "distributed generation" of electricity as a means of
decentralizing the commercial electricity grid, which suffers from
centralized generation plants and switching and transmission lines
that are sometimes old and in poor repair, such that a grid may
become unstable and prone to outages of electrical power. In
response and as a means of diminishing the risk of rising energy
costs to the consumer, it has become more prevalent to generate
electricity from renewable sources of energy using decentralized
devices located on buildings or on land or in yards belonging to
small commercial companies or even individuals. While it is most
common in remote locations that this renewable-sourced electricity
is generated solely for local consumption, in other locations where
a grid connection is available, electrical utilities are offering
"net metering". Net metering equipment allows "co-generation" of
electrical power, such that both the utility and the end user can
generate electricity. Since the bi-directional electric meter
accurately registers the flow of electricity in both directions,
net metering not only helps to maximize the value of distributed
generation, but does so with little cost to the consumer. In other
words, the meter spins forward when the customer uses more
electricity than is being produced, and spins backward when the
customer is producing more electricity than is needed.
[0013] Therefore, as interest in co-generation grows, there is a
need for better, more efficient renewable-energy electricity
generating devices. An improved VAWT capable of harnessing wind
from a full 360 degrees of rotation about the vertical axis would
be one such device. Desirably, the VAWT should also harness
vertically impinging wind and cyclonic wind. The VAWT also should
minimize inefficiencies arising from frictional losses. Preferably,
the VAWT materials should maximize strength and durability but have
a low cost of manufacture so as to be economically available to
consumers for use in individual households.
SUMMARY OF THE INVENTION
[0014] These and other benefits are found in the present invention
which provides a lift and drag-based vertical axis wind turbine in
which the vertical axis and foils mounted thereon are magnetically
levitated above the turbine's base, thereby reducing friction
within the system. The foils are shaped to maximize operation of
the system, regardless of the wind direction. More specifically,
the foils are three-dimensionally shaped about the vertical axis so
as to resemble the billowed sail of a sailing ship; hereinafter the
foils will be referred to as sails or vanes. The sails (or vanes)
capture wind through a full 360 degrees of rotation under any wind
condition. The system is further provided with an axial flux
alternator using variable resistance coils which can be
individually and selectively turned on or off depending on wind
conditions and required electrical draw requirements. The coils can
also be used to produce mechanical drag on the system if required
to brake the turbine in high wind conditions or for maintenance.
The system may be programmed to assess whether electricity
generated by the system can be or should be transmitted to a public
grid or stored locally on a chargeable battery, system. Finally,
the system may be programmed to report system usage such as the
amount of electricity produced, the amount of electricity used and
the amount of electricity sent to a grid or stored. Likewise, the
system can report outages to individuals and local authorities.
[0015] The system thus described is small, light in weight, and
easy to install upon a flat or peaked rooftop. This vertical axis
wind turbine is robust as to interaction with the weather. Most
importantly, the present invention is capable of effectively using
wind blowing from all sides simultaneously, including from above.
Since the present invention is able to utilize wind from all
directions, it can generate electricity even in low-speed winds.
Also, since the wind turbine is magnetically leviated, the present
invention is quiet in operation and, because the rotational
bearings do not support the weight of the turbine sails, the
bearings very seldom need replacement. The magnetic levitation
results in very little spinning resistance, and hence, increased
efficiencies. Efficiencies are also enhanced by the curved shape of
the vanes or sails.
[0016] It is an object of the present invention to provide a new
and improved wind turbine design.
[0017] A further object of this invention to provide a wind turbine
design which is susceptible of a low cost of manufacture with
regard to both materials and labor, and which accordingly is then
susceptible of low prices of sale to the consuming public, thereby
making wind generation of electricity economically available to the
buying public.
[0018] Another object of the present invention is to provide a wind
turbine design that is manufactured with materials used in
manufacture in order to maximize strength and durability while
minimizing weight. The vanes or sails of the present invention can
be manufactured from light, strong composite materials or light,
strong metals that are able to maintain their structural integrity
even in hurricane-force winds.
[0019] Another object of the present invention is to provide a wind
turbine design that allows the vanes or sails to be magnetically
levitated so that no bearings are needed between the rotor and the
base. This significantly decreases drag that might occur due to
gravity and friction.
[0020] Another object of the present invention is to provide a wind
turbine design that is capable of utilizing wind energy from all
directions. The sails are curved like those of a sailing ship in
order to maximize the opportunity to scoop wind (which is the
drag-driven component) from a larger area than a flat vane could.
This also protects the device from contrary or turbulent winds such
as might be prevalent during storms. Because of the sail shape, the
present invention can tolerate and utilize winds blowing even from
directly above the wind turbine, in a manner that other devices
cannot. This means that the wind turbine can continue to operate
during thunderstorms or hurricanes, or atop high buildings where
significant wind turbulence may exist either continuously or as an
intermittent condition. In such turbulent wind conditions, wind
turbines of the prior art would have to be curtailed or "feathered"
to prevent damage to the vanes and gearing of the wind turbine. The
present invention has no such vulnerability.
[0021] A further object of the present invention is to provide a
wind turbine design that has a vane design that enhances the
efficiency of the wind turbine by creating lift at certain
rotational points when the vane rotation is in opposition to the
direction of the wind. The sails are curved like those of a sailing
ship in order to allow the wind turbine to create lift similar to a
sailing ship in a "close haul." Not only does this increase the
efficiency of the wind turbine, but it also protects the device
from contrary or turbulent winds.
[0022] A further object of the present invention is to provide a
wind turbine design that has a graceful shape, which makes it
visually appealing, in a manner similar to "wind art."
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows a side view of a magnetic vertical axis wind
turbine of the present invention.
[0024] FIG. 2 depicts an exploded view of the magnetic vertical
axis wind turbine of the present invention.
[0025] FIG. 3 illustrates a top view of a magnetic vertical axis
wind turbine of the present invention.
[0026] FIG. 4 a cross section of the base of the magnetic vertical
axis wind turbine of the present invention.
[0027] FIG. 5 shows an elevation view of a magnetic vertical axis
wind turbine of the present invention.
[0028] FIG. 6 is a flow diagram illustrating certain functions of
the winds turbine's controller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] In the detailed description of the invention, like numerals
are employed to designate like parts throughout. Various items of
equipment may be omitted to simplify the description. However,
those skilled in the art will realize that such conventional
equipment can be employed as desired.
[0030] With reference to FIGS. 1 and 2, the magnetic vertical axis
wind turbine 10 of the present invention is illustrated.
Specifically, there is shown a substantially circular base 12
defined by a vertical edge 14 at its outer perimeter and a central
hub 16. A center rod 18 attaches to central hub 16 and extends
axially from base 12. Disposed around outer perimeter of base 12 on
vertical edge 14 is a plurality of magnetic transformers 20. An
axial shaft 22 having a first end 24, a second end 26 and axial
grooves 28 along its length is pivotally mounted on center rod 18.
Shaft 22 rotates axially relative to rod 18 and base 12. Center
bearings 19 may be positioned on rod 18 or within shaft 22 to
facilitate relative rotation and ensure axial alignment of shaft 22
and rod 18. In one preferred embodiment, shaft 22 is segmented into
multiple segments (in the case of FIG. 2, four segments) and
multiple bearings 19 are utilized so that the height of shaft 22
can be adjusted as desired. A top cap 21 may be placed over the top
most center bearing 19.
[0031] Mounted on shaft 22 is a substantially circular rotor or
cover 30 which has an outwardly extending surface 31 terminating at
an outer perimeter vertical edge 32. Disposed around the outer
perimeter edge 32 of rotor 30 is a plurality of magnets 34. Rotor
30 is mounted on shaft 22 so as to be concentric with base 12,
whereby the outer perimeter edge 32 of rotor 30 is adjacent the
outer perimeter edge 14 of base 12 such that magnets 34 are aligned
with transformers 20 in a horizontal plane. In one preferred
embodiment, sixty magnetic transformers 20 are provided on base 12
and sixty magnets 34 are provided on rotor 30. Center rod 18, being
attached in a fixed non-rotational position to base 12, in addition
to providing support for shaft 22 and rotor 30, also provides
alignment for base 12 and rotor 30 and hence the adjacent
transformers 20 and magnets 34.
[0032] A first levitating magnet 36 is mounted on base 12 and a
second levitating magnet 38 is mounted on rotor 30 so that magnet
36 and magnet 38 are adjacent one another when rotor 30 and base 12
are axially aligned. Those skilled in the art will understand that
the polarities of magnets 36 and 38 are such that the magnets repel
one another when mounted as described herein. In such case, rotor
30 will "levitate" above base 12 on center rod 18. The levitating
magnets 36, 38 enable rotor and vanes 42, or wind turbine portion
of the device, to "levitate" magnetically off of base 12, thus
providing substantially frictionless rotation of rotor 30 relative
to base 12 and obviating the need for wheels or bearings
therebetween. As such, the efficiency of the wind turbine 10 is
increased because less energy is needed to overcome the resistance
between rotor 30 and base 12. While any configuration of magnets 36
and 38 as disposed on corresponding base 12 and rotor 30 is
possible, in the preferred embodiment, each magnet 36,38 is ring
shaped and concentrically disposed in recesses 40 defined on base
12 and rotor 30.
[0033] A plurality of triangular shaped vanes 42 are mounted on
shaft 22. Each vane 42 is characterized by an inner edge 44, an
outer edge 46 and a lower edge 48. As further illustrated in FIG.
3, outer edge 46 is curved axially about inner edge 44 so as to
define an inner surface 50 and an outer surface 52 for vane 42. In
one preferred embodiment, inner edge 44 is linear, while edges 46
and 48 are curvilinear, thereby taking on the shape of the billowed
sail of a sailboat. In any event, inner edge 44 of vane 42 is
disposed to mount in an axial groove 28 of shaft 22 so that lower
edge 48 abuts surface 33 of rotor 30 and the distal end of lower
edge 48 terminates adjacent vertical edge 32 of rotor 30. Vanes 42
are preferably equally spaced about shaft 22 in the same direction
radially on top of rotor 30. In one preferred embodiment, eight
vanes 42 are utilized.
[0034] With reference to FIG. 4, one embodiment of a cross section
of the base 12 and rotor 30 of the magnetic vertical axis wind
turbine 10 is illustrated, and more specifically, the relative
positions of magnetic transformers 20 mounted on base 12 and
magnets 34 mounted on rotor 30 are shown. In this embodiment, edge
14 of base 12 is illustrated as being located inwardly of edge 32
of rotor 30, thereby protecting both transformers 20 and magnets 34
from external exposure. Additionally, center rod 18 is shown
secured in hub 16 of base 12. A recess 40 is shown in each of base
12 and rotor 30. Recesses 40 are axially positioned to face one
another and are each disposed for receipt of their corresponding
levitating magnet 36,38. A portion of shaft 22 (without any vanes
42 shown) is illustrated and shown attached to rotor 12.
[0035] Turning to the wind turbine component, or "wind engine", of
the invention, namely the vanes 42, the shape and placement of the
vanes are specifically provided to yield improvements in both
rotation torque and efficiency. There is a five-step sequence to
wind turbine technology that is generally known in the art: [0036]
1. Upwind Lift Phase. This begins approximately in the upwind
position and continues to approximately 60 degrees past it,
depending on wind and rotor speed conditions. [0037] 2. Downwind
Drag Phase. This begins at approximately 60 degrees downwind and
continues to around the 120 degree position. [0038] 3. Transitional
Phase. At about the 120 degree position, the airfoil rotates its
orientation by 90 degrees and converts its rotational energy into
rotor thrust by the law of conservation of rotational inertia.
[0039] 4. Leeward Lift Phase. Positioned crosswind by the
transitional phase, the airfoil now sweeps across the leeward side
of the system. [0040] 5. Upwind Phase. The airfoil returns to
windward, positioning itself for minimum drag.
[0041] In the present invention, power is produced in four of the
five phases, as more particularly described below.
[0042] The vertical axis wind turbine 10 is designed to be mounted
on a roof top. When the wind strikes the roof and building at
different angles throughout the year, the wind creates air currents
coming from different directions, sometimes simultaneously. For
example, if the wind is blowing from the other side of a roof peak,
force is created by the wind that hits the turbine 10 directly,
plus the wind that is redirected from hitting objects on the roof.
These objects on the roof include roof vents, television satellite
dishes, chimneys and the other elevated roofs. In addition, there
may be vortices of wind turbulence curling back from over the roof
and striking the turbine from above. Because of these conditions,
most roof mounted prior art VAWTs have been ineffective. However,
the vanes or sails 42 of the vertical axis wind turbine 10 of the
current invention are designed so that the wind can strike them
from all directions simultaneously; this then causes the wind
turbine 10 to spin faster.
[0043] As described above, each vane 42 preferably resembles a
ship's sail, configured for a "close haul" to the wind. The overall
visual effect gives the wind turbine 10 an appearance like an
"auger" or "impeller."
[0044] To the extent that wind strikes the wind turbine 10 from a
single direction, the curved shape of a vane 42 allows the wind
turbine 10 to catch the wind through 280 degrees of the rotation of
vane 42. Specifically, for approximately 20 degrees, vane 42 luffs
(does not catch any wind or face any wind)--similar to the sail of
a sailboat. Through the next 100 degrees, vane 42 develops lift
from the passage of the air over the curved shape of vane 42,
similar to a sailboat with its sail configured for a "close haul".
Through another 40 degrees, vane 42 of the wind turbine 10 moves in
opposition to the wind, creating "drag". Through the final 20
degrees, vane 42 is in a luff position again.
[0045] When wind impinges on all vanes 42 of the wind turbine 10,
some vanes 42 receive a "push" through 180 degrees at the same time
as other vanes 42 receive wind through the 20 degrees of luff,
while still other vanes 42 receive force through the 100 degrees of
lift and the remaining vanes 42 receive wind-force through the
other 40 degrees of luff. As such, power is produced from four of
the five phases discussed above, which is equivalent to at least
280 degrees out of 360 degrees of rotation. Further, because of the
multiple vanes 42 utilized in turbine 10, the drag and luff
portions of one vane 42 may be offset by the other vanes 42 at any
one moment in time.
[0046] Significantly, the combined effect of push on one side and
lift on the other side gives the wind turbine 10 the ability to
spin faster than the speed of the wind from any one direction.
Specifically, in a multiple wind-direction situation, i.e. when
cyclonic winds blow from several directions at once or when the
wind is blowing straight down upon the wind turbine 10 from above,
all vanes 42 are experiencing more lift than drag through their
entire rotation. The effect is that the wind turbine 10 actually
spins faster when having winds strike it from more than one
direction, and spins quickest of all when the wind is blowing from
above. As such, it is possible for vanes 42 to spin much faster
than the speed of the wind.
[0047] With respect to generation of electricity, the magnetic
transformers 20 and magnets 34 are the principal components of what
may be referred to as the axial flux alternator for turbine 10. In
the preferred embodiment, magnetic transformers 20 may be a cored
coil or a coreless coil and magnets 34 are passive magnets. Those
skilled in the art will understand that the term "axial flux"
refers to a type of alternator where magnets are mounted on disks
and the flux between them is parallel to the axis of the shaft and
is desirable for generating an electric current even when
rotational speed is low. An electric current is produced by
magnetic transformer 20 as magnets 34 are rotated past the
transformers. In any event, the axial flux alternator arrangement
described above is used in the current invention to generate an
electric current. The magnetic transformers 20 are incorporated as
part of the circuit of the axial flux alternator. Moreover, while
FIG. 4 illustrates edge 14 of base 12 being located inwardly of
edge 32 of rotor 30, the relative positions of edges 14 and 30
could be reversed or an additional edge 14 carrying additional
transformers 20 could be located outwardly of edge 32 and magnets
34 so as to maximize the amount of electricity produced by turbine
10.
[0048] While one preferred embodiment of the invention has been
described with 60 magnets 34 and 60 magnetic transformers 20, in
another preferred embodiment of the invention, turbine 10 includes
100-300 magnets 34 which pass over 100-400 magnetic transformers
20, or coils of wire, thus generating electricity by induction. In
one example, the frequency of the current typically ranges from 100
cycles to 7500 cycles. Preferably, the current is first converted
to DC and then back to AC 60 cycle current before it is conveyed to
either electrically-owered machines (not shown), an electrical
storage system, such as a battery system (not shown) or connected
to a commercial electrical grid (not shown) for use by the local
electrical utility.
[0049] One novel feature of the turbine 10 is the ability to
selectively activate and deactivate magnetic transformers 20 as
needed to control rotational drag. One drawback to the VAWTs of the
prior art is that, with a full generator load holding it back, they
are often very difficult to get started, i.e., generating
sufficient torque to overcome friction creating drag on the
rotating hub. In some prior art VAWTs, an electric motor was used
to achieve a minimum rotation speed for the vanes (of those
designs) in order to overcome this start-up drag. Because of the
magnetic levitation system of the current invention, much of this
frictional resistance or drag has been eliminated. However, the
turbine 10 of the present invention also provides magnetic
transformers 20, or variable resistance coreless coils, that can be
turned on and off by a computer (not shown) to vary the drag on
rotor 30. These magnetic transformers 20 do not produce electricity
or drag on the system until they are turned on. This means that the
drag on the wind turbine 10 can be controlled according to its
rotational speed. The higher the speed, the more magnetic
transformers 20 that are turned on. The turbine 10 has several
hundred magnetic transformers 22 that can be turned on and off to
achieve the desired drag. In this regard, the magnetic transformers
22 can also operate to slow down the wind turbine 10 in high winds,
but do not impede the rotation when winds are light and of little
strength.
[0050] A controller (not shown) for turbine 10 determines the
number of magnetic transformers 20 that should be active at any
given time. Preferably, a small number of magnetic transformers 20
are active at all times. The turbine 10 may include a sensor (not
shown) that can determine the rotational speed of the wind turbine
10. The controller compares the rotational speed of turbine 10
against the amount of electricity that is being produced from the
active magnetic transformers 20. Once the controller has determined
that turbine 10 is spinning faster than the programmed optimum rpm
range for a given amount of electrical generation, the controller
may turn on additional magnetic transformers 20. On the other hand,
if the rotational speed of turbine 10 slows, the controller may
then turn off a select number of magnetic transformers 20 in order
to increase the rotational speed.
[0051] The wiring on the magnetic transformers 20 consists of four
different patterns. All of the magnetic transformers 20 are wired
to one of these patterns. The patterns keep the wave peak/trough
canceling effect from reducing the amount of electricity produced.
The patterns are North-North-South Gap-South-South North Gap. The
role of the magnet orientation is thus: all the coils
(transformers) that are going to be over a magnet oriented to a
specific orientation are named the same and wired together. This
means that all of the transformers 20 in the North pattern will be
over a North pole at the same time, and thereafter leave that pole
at the same time. The coils used in wiring base 12 (which does not
rotate, but remains stationary) are of coreless type because
coreless coils only provide magnetic resistance when they are
connected to a load. The interaction between the rotating magnets
34 and the stationary coils 20 causes generation of electrical
current. The high frequency electrical current from each wiring
pattern flows to a rectifier to be converted into direct current
(DC).
[0052] Finally, the foregoing controller may also be programmed to
assess whether electricity generated by turbine 10 can be
transmitted to a public grid or should be stored locally, such as
on a chargeable battery system. More specifically, the controller
may be programmed to access or otherwise receive external data
related to co-generation, power costs, and the availability of a
public grid to receive co-generated electricity from the turbine
10. Once the controller has evaluated these parameters, it can take
appropriate action to control the electricity by deciding where to
send the electricity. FIG. 6 illustrates for example, if the
controller determines it is not profitable to send electricity to a
public grid, then the controller may direct the electricity to a
local storage device. In another example, there may be no public
draw connection or it could be that the need of the local public
grid for co-generated electricity at that moment is zero. Likewise,
the controller may evaluate the status of a local storage system,
such as a large capacity uninterruptible power supply (UPS) and
maintain a local database of such. The controller may decide to
send some of the electricity to a local utility grid and some to a
local storage system. For example, if the local storage system is a
rechargeable battery system or a UPS, then the controller, by means
of sensors, may determine whether the battery system is charged to
100% of capacity and take appropriate action to recharge to such a
level. Local data may also consist of a historical database battery
efficiency. Similarly, the controller may also monitor local energy
usage and maintain a local database of historical energy usage and
thus be ready to provide more energy at peak hours, less energy at
off-peak hours, or generate a report or `alert` if the local public
grid is anomalous because of usage that could signal an equipment
malfunction or other noteworthy condition. This is an important
safety feature that can protect both the user of the wind turbine
(for electricity generation), and also the electricians and line
crews of the electricity-generation utility. It can also assist the
utility in mapping or pinpointing localities where a grid outage
exists, as discussed further below.
[0053] If a local battery system is fully charged, then the
controller may evaluate the value of the generated electricity in
terms of energy market prices at that moment in terms of the price
to efficiency ratio of the other connected storage device(s). The
controller then decides whether the return amount of electricity
justifies sending the electricity to one or another specific
storage device.
[0054] Finally, the controller may be programmed to report system
usage such as the amount of electricity produced, the amount of
electricity used and the amount of electricity sent to a grid or
stored. Likewise, the system can report outages to individuals and
local authorities. The controller may use a regular telephone line,
WLAN, WIFI, or cellular telephone connection to obtain external
data and to report both usage and outage conditions. Typically, a
usage report would consist of the following: the amount of
electricity produced by the wind speed (if equipped with an
external anemometer), the amount of electricity used and the amount
of electricity sent to the local electrical grid.
[0055] Outage reporting may also occur when the meter or safety cut
off switch indicates that there is no electricity on the grid side
connection. A signal or report to the outage reporting center may
be generated to indicate that there has been an outage and to
confirm that the unit is no longer sending electricity to the grid.
This signal or report may then be passed on to the local utility to
create an outage "footprint" or map showing the units reporting the
outage and the units not reporting.
[0056] While certain features and embodiments of the invention have
been described in detail herein, it will be readily understood that
the invention encompasses all modifications and enhancements within
the scope and spirit of the following claims.
* * * * *