GB2460861A

GB2460861A - Image formation on rotating wind turbine blades by persistence of vision of array of light sources supported by turbine blade

Info

Publication number: GB2460861A
Application number: GB0810778A
Authority: GB
Inventors: James Sirmon; Anthony Cole
Original assignee: Litelogic IP Ltd; Litelogic Ltd
Current assignee: Litelogic IP Ltd; Litelogic Ltd
Priority date: 2008-06-12
Filing date: 2008-06-12
Publication date: 2009-12-16
Also published as: GB0810778D0

Abstract

A wind turbine, comprising one or more turbine blades 4 rotatable around a common axis, comprises an array of light sources, e.g. RGB LEDs, supported on at least one of the turbine blades and adapted to form an image visible to an observer by virtue of persistence of vision. Each light source in the array is connected to a controller 15 adapted to modulate the intensity of light emitted as it rotates around the common axis such that the light sources in combination cause the image to be formed. More than one of the turbine blades may support an array of light sources and the light sources of each separate array may be spaced apart such that their paths are interlaced. The system may use power generated by the turbine or it may be powered by solar cells. Batteries may be provided to store power and to drive the turbine and provide power for the controllers and light sources when there is insufficient wind. The light sources may be connected to the controller via an optical or infrared link 20, 21 and power may be supplied via a slip ring 23. A photosensor 17 may be provided to determine ambient light and the intensity of the light sources may be adjusted so that as the ambient light decreases, the intensity of illumination also decreases.

Description

WIND TURBINE

This invention relates to a wind turbine.

Wind turbines are well-known. They normally comprise a plurality of turbine blades, typically two or three, coupled together by a hub which is coupled to one end of a drive shaft. As the wind blows, the turbine blades rotate, thereby rotating the drive shaft along with a generator coupled to the other end of the drive shaft. Thus, when the wind blows the generator generates power which can be distributed to appliances for consumption.

Wind turbines have struggled to achieve acceptance by the public because they are considered unsightly and costly. This is especially true for small-scale installations.

In accordance with one aspect of the present invention, there is provided a wind turbine comprising one or more turbine blades rotatable around a common axis and coupled to a generator system such that power is generated as the one or more turbine blades rotate, the wind turbine further comprising a first array of light sources supported by a first one of the turbine blades, each light source in the first array being connected to a controller adapted to modulate the intensity of light emitted by each light source as it rotates around the common axis such that the light sources in combination cause a desired image to be visible to an observer by virtue of persistence of vision.

By providing at least one of the turbine blades of a wind turbine with an array of light sources and controlling these light sources such that a desired image is caused to be visible to an observer by virtue of persistence of vision as the turbine blades rotate, the wind turbine achieves an additional function. Specifically, apart from power generation, it now acts as a display system. This opens up a new arena for wind turbines because they can also now be used for purposes such as advertising on rooftops of commercial premises, thereby improving their acceptability and helping companies recoup the cost of their installation.

In one embodiment, only the first one of the turbine blades supports an array of light sources.

The wind turbine may typically comprise a plurality of turbine blades. In this case, it is possible that at least one of the plurality of turbine blades does not support an array of light sources.

However, it is preferable that more than one of the plurality of turbine blades supports an associated array of light sources, each light source being connected to a controller adapted to modulate the intensity of light emitted by each light source as it rotates around the common axis such that the light sources in combination cause a desired image to be visible to an observer by virtue of persistence of vision.

Typically, each of the plurality of turbine blades will support an associated array of light sources.

When more than one or each of the plurality of turbine blades supports an associated array of light sources, the light sources in each array may be arranged so that each light source traverses along a unique path around the common axis, whereby the paths traversed by the light sources of each array are interlaced.

In a preferred embodiment, the power generated by the generator system is used to operate the controller and to illuminate the light sources.

This is a particularly useful aspect of the invention because whilst display systems, such as that incorporated in this wind turbine are known (as for example described in our published PCT application W020061021788), they have always been restricted in that they can only be sited where there is a convenient source of power. Alternatively, an external generator or battery system had to be provided and maintained (for example, by recharging or replacing the battery or refueling the generator as required). Thus, this invention has broadened the arena within which such displays can be used as an external source of power is no longer required for operation of the display. The display may therefore be used in remote locations away from the convenience of mains power, provided only that there is adequate wind to cause the turbine blades to rotate sufficiently fast.

The generator system may comprise a dynamo.

Preferably, the generator system is coupled to a power storage device, such as a battery, for storing power generated by the generator system. In this case, the power stored in the power storage device may be used to drive the dynamo as a motor, operate the controller and illuminate the light sources when there is insufficient wind to cause the turbine blades to rotate.

In one embodiment, the generator system comprises an external power source, such as a solar cell.

The wind turbine may further comprise a sensor for sensing the ambient light level and supplying an output signal representing the ambient light level to the controller, wherein the controller is further adapted to adjust the intensity of the light emitted by the light sources depending on the ambient light level in accordance with a predetermined characteristic.

This allows the controller to respond to a decreasing light level by reducing the intensity of light emitted by the light sources, a lower level of intensity being required for the display to be visible in lower ambient light conditions, for example at night.

This helps improve the efficiency of the system.

Typically, the light sources are light emitting diodes (LEDs). These may be single colour LEDs for a monochromatic display, or preferably will be full colour ROB LEDs or arranged as a triad of a red, green and blue LED to provide the illusion of full colour.

Preferably, the or each array of light sources is embedded within a respective one of the turbine blades.

In this case, it is possible to aid cooling of the light sources by providing the or each turbine blade with a conduit running from a first point on its outer surface past the respective array of light sources to another point on its outer surface, the conduit allowing passage of air past the array of light sources as the turbine blade rotates.

When the light sources are embedded within the turbine blades then the light sources in the or each array are typically mounted on a substrate, the height of each light source with respect to the substrate being set to follow the profile of the outer surface of the turbine blade. This helps minimise wind resistance, turbulence and noise.

Typically, the or each turbine blade is manufactured by injection moulding.

In one embodiment, the light sources are connected to the controller via an optical or infrared link.

In this embodiment, the optical or infrared link typically comprises an emitter situated at one end of a drive shaft coup'ing the turbine blades and generator system and a receiver situated at the other end of the drive shaft, the drive shaft having a central, longitudinal base between its two ends.

Typically, power is supplied to the light sources via a slip ring.

An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a wind turbine for use in this invention; Figure 2 shows a b'ock diagram of the electrical system; and Figure 3 shows a cross-section through part of the wind turbine.

Figure 1 shows a wind turbine 1 comprising a housing 2 to the rear of which is attached a fin 3. The housing 2 will normally be rotatably mounted on a stand (not shown) such that as the wind blows the fin 3 causes the housing 2 to rotate on the stand such that the turbine blades 4 are facing directly into the wind.

The turbine blades 4 are each coupled to a hub 5 which is rotatably mounted on the front end of housing 2. The hub 5 is connected to a drive shaft (not shown), the other end of which is connected to a dynamo (not shown) situated within the housing 2.

As the wind blows the turbine blades 4 rotate, thereby rotating the hub, drive shaft and dynamo which generates power as a result of the rotation.

A block diagram of the electrical system is shown in Figure 2. The dynamo 10 is connected to a switching system 11, the operation of which will be described later.

The switch is connected to a charging circuit 12 which controls the charging of a battery 13. The battery may be any conventional type, such as Lithium-ion, nickel metal hydride, nickel-cadmium or lead-acid. The charging circuit may also receive power for charging battery 13 from an external source such as solar panel 14. This ensures that the battery 13 is still charged when the wind speed drops, provided that there is sufficient sunlight.

The battery 13 is also connected directly to the switching system 11 to provide power in the event that there is insufficient wind to drive the wind turbine.

The switching system 11 is also connected to a controller 15. The controller 15 comprises interface circuitry for receiving image data and a memory for storing the image data. The controller 15 also comprises pulse width modulator (PWM) circuitry for controlling the intensity of illumination of LEDs mounted in a linear array on printed circuit boards (PCBs) 16a to 16e. Each FOB is embedded within a respective one of the turbine blades 4 such that the LEDs remain visible, as will be explained below.

Each one of the LEDs on PCBs 16a to 16e is a full-colour RGB LED, and the PWM circuitry therefore supplies discrete red, green and blue component signals to each LED to enable a full-colour image to be generated.

The image data is clocked out of the memory and supplied to the PWM circuitry as the turbine blades 4 rotate, thereby causing the image represented by the image data to be visible to a distal observer by virtue of persistence of vision. The image data may represent either a static or moving image (i.e. a video image).

The controller 15 keeps track of the rotation of the PCBs I 6a to 1 6e using a Hall-effect device that is actuated by the passage of a magnet mounted, for example, on the drive shaft of the dynamo 10. The Hall-effect device is therefore actuated once for each rotation of the turbine blades 4, allowing the clocking of data from the memory to be synchronised to their rotation.

The switch system 11 is used to control the routing of power within the electrical system as is required to cope with changes in wind speed. It may be operated under computer control, or it may be a simple system comprising merely diodes.

When the wind speed is sufficient for the dynamo 10 to produce an adequate amount of power, the switching system 11 routes the power generated by the dynamo 10 to the controller 15 and to the PCBs 16a to 16e. Surplus power is supplied to charging circuit 12, which charges battery 13.

However, if the wind speed drops so that dynamo 10 can no longer produce adequate power to illuminate the light sources then switching circuit 11 routes power from battery 13 to the controller 15 and to dynamo 10, thereby operating it as a motor. This ensures that the turbine blades 4 (and hence the arrays of LEDs mounted on PCBs 16a to 16e) continue to rotate, thereby maintaining the display of the desired image.

The switching circuit 11 may be configured to allow the battery 13 to provide all the power to drive the dynamo 10 as a motor, to illuminate the arrays of LEDs on PCBs 16a to 16e and to power the controller 15 when the wind speed has dropped so much that the turbine blades are no longer rotated by it. It may also be configured to allow the battery 13 to provide additional power when the wind speed simply drops slightly but is still adequate to cause some rotation of the turbine blades. This ensures that the dynamo 10 continues to rotate at the required speed for the persistence of vision effect to cause the desired image to be visible.

An ambient light sensor 17 is connected to controller 15. The sensor 17 will typically be a photocell. The controller 15 responds to the output signal from sensor 17 by adjusting the intensity of the light emitted by the LEDs on PCBs 1 6a to 1 6e such that as the amount of ambient light decreases, the intensity of illumination of the LEDs decreases also. This ensures higher efficiency of the device and can be done because a lower level of intensity is required to make a good display in low ambient light conditions.

Figure 3 shows a view of part of a wind turbine from the side in partial cross-section. As can be seen, the dynamo lOis attached to one end of a drive shaft 18, the other end of which is coupled to hub 5. Drive shaft 18 has a centrally located bore 19 running along its entire length, thereby allowing the PWM signal to be transmitted by controller 15 to PCB 16a via an infrared or optical emitter 20 (typically an LED) and a corresponding receiver 21 coupled to POB 1 6a. LED driver circuitry on the PCBs 16a to 16e provides a high power signal to the LEDs depending on the PWM signal, causing the LEDs to illuminate at the desired intensity with the desired colour. Power for this and the other functions on the PCBs 16a to 16e is supplied along cables 22a and 22b which are connected via slip ring 23, thereby enabling cable 22b to rotate with hub 5 relative to cable 22a.

The assembly of one of the turbine blades 4 and one of the PCBs 16a to 16e is typically formed by first manufacturing and testing the PCB 16a to 16e and then injection moulding the turbine blade 4 around it. In this way, the PCB 16a to 16e acts as a structural part of the turbine blade 4, helping to stiffen the turbine blade 4 both longitudinally and torsionally.

The heights of the LEDs mounted on PCBs 1 6a to 1 6e will be individually adjusted during manufacture such that the LEDs protrude slightly through the surface of turbine blade 4 after injection moulding but closely follow its profile, thereby helping to reduce wind resistance, turbulence and noise. The height of the LEDs is conveniently set by placing a template having the same shape as the surface profile of the turbine blade 4 on top of PCBs 16a to 16e as the LEDs are soldered to it.

This ensures that each has the correct height relative to the PCB 16a to 16e to follow the required profile of turbine blade 4.

To prevent the PCB 16a to 16e overheating, an air conduit 4 is provided running from the outer surface of turbine blade 4 roughly longitudinally towards its centre, emerging at another point on the surface. As the turbine blade 4 rotates, this forces air through the conduit which causes the air to pass over a heat sink 25 mounted on FOBs 16a to 16e.

During manufacture, the longitudinal registration of each FOB 16a to 16e with respect to the turbine blade 4 in which it is mounted may be adjusted. Doing this allows the LEDs on each of the PCBs 16a to 16e to describe a unique path as it rotates. As explained in our prior published PCT application W02006/021 788, this has the effect of causing the paths described by the LEDs on one of the PCBs 16a to 16e to interlace with the paths described by the LEDs on the other PCBs 16a to 16e as they rotate. Therefore, a certain resolution is achieved without having to densely pack the LEDs on a single PCB. Instead, the LEDs may be distributed over the five FOBs 16a to 16e allowing large and brighter LEDs to be used.

The term "interlace" is used in this specification in the sense that it is commonly used in television technology. That is to refer to the alternate scanning of an image in two or more sets of alternate lines.

Claims

CLAIMS1. A wind turbine comprising one or more turbine blades rotatable around a common axis and coupled to a generator system such that power is generated as the one or more turbine blades rotate, the wind turbine further comprising a first array of light sources supported by a first one of the turbine blades, each light source in the first array being connected to a controller adapted to modulate the intensity of light emitted by each light source as it rotates around the common axis such that the light sources in combination cause a desired image to be visible to an observer by virtue of persistence of vision.
2. A wind turbine according to claim 1, wherein only the first one of the turbine blades supports an array of light sources.
3. A wind turbine according to claim 1, wherein the wind turbine comprises a plurality of turbine blades.
4. A wind turbine according to claim 3, wherein at least one of the plurality of turbine blades does not support an array of light sources.
5. A wind turbine according to claim 3, wherein more than one of the plurality of turbine blades supports an associated array of light sources, each light source being connected to a controller adapted to modulate the intensity of light emitted by each light source as it rotates around the common axis such that the light sources in combination cause a desired image to be visible to an observer by virtue of persistence of vision.
6. A wind turbine according to claim 5, wherein each of the plurality of turbine blades supports an associated array of light sources.
7. A wind turbine according to claim 5 or claim 6, wherein the light sources in each array are arranged so that each light source traverses along a unique path around the common axis, whereby the paths traversed by the light sources of each array are interlaced.
8. A wind turbine according to any of the preceding claims, wherein the power generated by the generator system is used to operate the controller and to illuminate the light sources.
9. A wind turbine according to any of the preceding claims, wherein the generator system comprises a dynamo.
10. A wind turbine according to any of the preceding claims, wherein the generator system is coupled to a power storage device, such as a battery, for storing power generated by the generator system.
11. A wind turbine according to claim 10, wherein the power stored in the power storage device is used to drive the dynamo as a motor, operate the controller and illuminate the light sources when there is insufficient wind to cause the turbine blades to rotate.
12. A wind turbine according to any of the preceding claims, wherein the generator system comprises an external power source.
13. A wind turbine according to claim 13, wherein the external power source is a solar cell.
14. A wind turbine according to any of the preceding claims, further comprising a sensor for sensing the ambient light level and supplying an output signal representing the ambient light level to the controller, wherein the controller is further adapted to adjust the intensity of the light emitted by the light sources depending on the ambient light level in accordance with a predetermined characteristic.
15. A wind turbine according to any of the preceding claims, wherein the light sources are light emitting diodes.
16. A wind turbine according to any of the preceding claims, wherein the or each array of light sources is embedded within a respective one of the turbine blades.
17. A wind turbine according to claim 16, wherein the or each turbine blade is provided with a conduit running from a first point on its outer surface past the respective array of light sources to another point on its outer surface, the conduit allowing passage of air past the array of light sources as the turbine blade rotates.
18. A wind turbine according to claim 16 or claim 17, wherein the light sources in the or each array are mounted on a substrate, the height of each light source with respect to the substrate being set to follow the profile of the outer surface of the turbine blade.
19. A wind turbine according to any of the preceding claims, wherein the or each turbine blade is manufactured by injection moulding.
20. A wind turbine according to any of the preceding claims, wherein the light sources are connected to the controller via an optical or infrared link.
21. A wind turbine according to claim 20, wherein the optical or infrared link comprises an emitter situated at one end of a drive shaft coupling the turbine blades and generator system and a receiver situated at the other end of the drive shaft, the drive shaft having a central, longitudinal base between its two ends.
22. A wind turbine according to any of the preceding claims, wherein power is supplied to the light sources via a slip ring.