System for automatic directional adjustment of a console relative to the sun's position

Abstract

A system for automatic directional adjustment of a console (1) relative the sun's (LS) position, comprisinga power system (31) comprising a power unit (313), a tilting actuator (311) and a rotation actuator (312) arranged to tilt and rotate the console (1), respective-ly, anda control system (3) arranged to control the power unit (313), the tilting ac-tuator (311), and the rotation actuator (312),c h a r a c t e r i s e d i n that the control system (3) comprises a programmable controller (32) connected to an array (323) of photo sensors (323b),the control system (3) being arranged to equalize a light intensity at each of the photo sensors (323b) by facing the array (323) of photo sensors (323b) to-wards the light source (LS) through tilting and rotation of the console (1).

Description

[0001] SYSTEM FOR AUTOMATIC DIRECTIONAL ADJUSTMENT OF A CONSOLE RELATIVE TO THE SUN’S POSITION

[0002] A system for automatic directional adjustment of a console relative the sun’s posi tion is disclosed. More specifically the invention comprises a power system includ- ing a power unit, a tilting actuator and a rotation actuator arranged to tilt and rotate the console, respectively, and a control system arranged to control the power unit, the tilting actuator, and the rotation actuator.

[0003] It is known that active two-axis tracking systems allow optimal use of all solar radi ation energy. Currently, active two-axis tracking systems have a system based on Maximum Light Detection (MLD) technology, achieving performance increases of approximately 45% for photovoltaic plants compared to stationary plants. Said technology comprises intelligent MLD-based tracking using specific power units based on complex microprocessors whose configuration includes the use of algo rithms, local sensors and centralized control plants. Current technologies imply large economic investment, as well as constant maintenance and upgrade costs of systems used for effective solar tracking.

[0004] The invention has for its object to remedy or to reduce at least one of the draw backs of the prior art, or at least provide a useful alternative to prior art.

[0005] The object is achieved through features, which are specified in the description be- low and in the claims that follow.

[0006] A system for automatic directional adjustment of a console relative a light source’s changing position, e.g. the sun’s position, has been provided. A console tiltable about a horizontal axis is arranged pivotal about an upright axis of a rack that is attached to a base. The console may be arranged to carry one or more elements that is intended to face the light source, like solar panels arranged for generation of electric power, heating of a liquid, e.g. water for heating of a building or water for consumption, etc.

[0007] The tilting and the pivoting of the console is performed by a control system com prising a power system connected to a programmable controller. The power sys tem comprises several actuators controlled by a power unit. In one embodiment the programmable controller includes a Programmable Logic Controller (PLC) and a Proportional-Integral-Derivative (PID) controller.

[0008] An array of photo sensors is arranged on the console and is connected to the pro grammable controller. In one embodiment, wherein the array is forming a block of narrow-spaced photo sensors adjacent photo sensors are separated by light-proof panels arranged to shade one or more photo sensors if the photo sensor array is not directed straight towards the light source. In one embodiment the array may comprise four photo sensors symmetrically arranged in a 2x2 matrix where the mentioned light-proof panels separate each sensor into a separate area as will be exemplified in the following.

[0009] Alternatively, the photo sensors may be distributed about an array centre, e.g. in a narrow block or scattered like in each corner of the console, wherein a centre axis of each photo sensor is oriented at an angle relative a centre axis of the array, thus causing different incident light intensity if the array centre axis is not coincid ing with the incident light.

[0010] In one embodiment the photo sensors may be photoresistors. A photoresistor (al so known as a light-dependent resistor, LDR, or photo-conductive cell) is a pas sive component with an electrical resistance dependent on the incident light on the photoresistor’s sensitive surface. The resistance of a photoresistor usually de creases with increase in incident light intensity.

[0011] When the individual photo sensors of the array are exposed to different incident light intensity, the connected programmable controller monitors different signal values generated in the various sensors. The programmable controller is pro- grammed to maintain substantially equal signal values from every sensor, thus generating control signals to the actuators to redirect the console for re establishing equal light intensity to each of the photo sensors. Thus, the console is adapted to maintain its orientation relative the sun’s continuously changing posi tion during the day.

[0012] In one embodiment, the actuators may be hydraulic actuators, e.g. linear actuators in the form of hydraulic cylinders and / or rotational actuators in the form of hydrau lic motors, powered by a hydraulic power unit via directional valves connected to the programmable controller. Preferably, the hydraulic power unit is provided with an accumulator, which, when exposed to sunshine, heats, thus expanding a fluid, causing the pressure of the hydraulic liquid in the control system to increase with out the use of a pump included in the hydraulic power unit. The accumulator may include the same hydraulic fluid as in the rest of the control system, or the accu mulator may include a fluid separated from the hydraulic fluid by means of a blad der, piston or similar. In one embodiment, the designated, separated fluid in the accumulator may be chosen based on thermal expansion coefficient. In one em bodiment, the accumulator may include a liquid with a relatively high thermal ex pansion coefficient. Non-limiting examples of such a high expansion liquids are diesel and petrol.

[0013] Preferably, the programmable controller may be arranged to redirect the console at adjustable intervals, e.g. every 30 minutes, however longer or shorter intervals are also envisioned. In an alternative embodiment, the programmable controller may be continuously redirecting the console. Furthermore, according to previously registered hour and altitude of sunset and sunrise, the programmable controller may preferably arranged to redirect the console to an appropriate sunrise position after sunset.

[0014] In one embodiment, the power system may be arranged with means for preadjust ing the tilting and rotation speed of the console, e.g. to allow the console to be re directed within a predefined interval, such as 30 seconds.

[0015] More specifically, the invention relates to a system for automatic directional ad justment of a console relative the sun’s position, the system comprising a power system comprising a power unit, a tilting actuator and a rotation actuator arranged to tilt and rotate the console, respectively, and a control system arranged to control the power unit, the tilting actuator and the rotation actuator, wherein the control system comprises a programmable controller connected to an array of photo sensors, the control system being arranged to equalize a light intensity at each of the photo sensors by facing the array of photo sensors towards the light source through tilting and rotation of the console.

[0016] The photo sensors may be attached to the console. However, in a system where multiple such consoles are provided and adapted to self-orient in the same direc tion, it may be sufficient if one such array of photo sensors is provided, such as attached to one of the consoles. The control system may then be adapted to con- trol multiple consoles based on input from a single array of photo sensors.

[0017] The programmable controller may comprise a programmable logic controller (PLC) and a proportional-integral-derivative (PID) controller. An effect of this is that standard programming tools can be used for the programming of the system.

[0018] The photo sensors may be photoresistors, whereby a wide range of standardized, low-cost photo sensors are available for design and maintenance purposes.

[0019] The array of photo sensors may comprise four photo sensors distributed about an array centre axis. An effect of this is that a simple, yet very precise control of the tilting and rotation of the console is obtained for optimised solar irradiance. Adjacent photo sensors may be separated by light-proof panels that are arranged to shade one or more narrow-spaced photo sensors if a centre axis of the array of photo sensors is not coinciding with incident light from the sun. An effect of this is that the difference in light intensity is generated by use of a simple means.

[0020] Each photo sensor may be distributed about an array centre axis, a centre axis of each photo sensor being oriented at an angle relative the array centre axis. An effect of this is that the extension of the sensor array can be enlarged, e.g. to each corner of the console.

[0021] The power system may be a hydraulic system, wherein the power unit may com prise a hydraulic pump and directional valves arranged to control a first hydraulic cylinder and a second hydraulic cylinder. An effect of this is that the power system can be manufactured and maintained by easily accessible components requiring little maintenance.

[0022] The power system may comprise an accumulator exposable to incident light from the sun and arranged to affect a hydraulic pressure in the hydraulic system as ex- plained above. An effect of this is that a required hydraulic pressure is maintained over an extended period without the need of running the hydraulic pump, thus re ducing power consumption.

[0023] The programmable controller may be arranged to redirect the console at adjusta ble intervals. An effect of this is that the redirection procedure can be set accord- ing to user’s need.

[0024] The power system may be arranged with means for preadjusting the tilting and rotation speed of the console. An effect of this is that the redirection movement can be properly set independently of the selection of power unit and actuator siz es. The programmable controller may be arranged to redirect the console to an ap propriate sunrise position after sunset according to previously registered hour and altitude of sunset and sunrise. An effect of this is that the assigned solar panel is in position prior to sunrise.

[0025] In the following are described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

[0026] Fig. 1 shows in perspective a tiltable and rotatable console arranged on a rack, the console being arranged to carry one or more elements that is intended to face the sun; Fig. 2 shows in more details the console arranged on top of the rack;

[0027] Fig. 3 shows a schematic overview of a control system arranged for auto matic directional adjustment of a console; and

[0028] Fig. 4 shows a schematic overview of a hydraulic system arranged for tilting and rotation of the console relative the rack;

[0029] Fig. 5a shows in detail a first embodiment of a partly shaded photo sensor array; and

[0030] Fig. 5b shows in detail a second embodiment of the photo sensor array.

[0031] Any positional indications refer to the position shown in the figures. In the figures, same or corresponding elements are indicated by same reference numerals. For clarity reasons, some elements may in some of the figures be with out reference numerals.

[0032] A person skilled in the art will understand that the figures are just principal draw ings. The relative proportions of individual elements may also be distorted. In figures 1 and 2 a tiltable and rotatable console 1 carrying a solar panel 11 is attached on top of a console bracket 21 of an up-right rack 2. The console bracket 21 is rotatable about a centre axis of the rack 2. The console 1 is connected to the console bracket 21 by two pivot joints 12 and two first actuators 311 arranged to tilt the console 1 about the pivot joints 12. The rotation of the console bracket 21 is performed by a second actuator 312 as shown schematically in figures 3 and 4. The first and second actuators 311, 312 are here shown as hydraulic cylinders forming portions of a hydraulic system 31 (explained below).

[0033] Reference is now made to figure 3. A control system 3 arranged to tilt and rotate the console 1 and the assigned solar panel 11 comprises a power system 31 , here shown as a hydraulic system, and a programmable controller 32. The power sys tem 31, which is shown in more detail in figure 4, comprises a power unit 313 ar ranged to receive signals from the programmable controller 32 for tilting and rota tion of the console 1 relative the rack 2. The programmable controller 32 comprises a programmable logic controller (PLC) 321 and a proportional-integral-derivative (PID) controller connected to a photo sensor array 323 arranged about an array centre axis 323a and attached to the console 1 . The photo sensor array 323 is here shown with four photo sensors 323b arranged in a sensor block wherein adjacent photo sensors 323b are sepa rated by a shading panel 323d (see also figure 5a for more details). The shading panels 323d cause the intensity of incident light LSI on one or more photo sensors 323b to change by shading if the array centre axis 323a is not coinciding with the incident light LSI, i.e. the photo sensor array 323 not being directed at a light source LS in the form of the sun.

[0034] The programmable controller 32 is programmed to maintain substantially equal light intensity at every photo sensor 323b of the photo sensor array 323 by control ling the tilting and rotation of the console 1 to re-establish a position wherein the photo sensor array 323 is facing the sun LS. Preferably, the repositioning proce dure is performed at regular intervals, e.g. every 30 minutes.

[0035] The photo sensors 323b may be photoresistors providing an ohmic resistance de pendent on the intensity of the incident light. If a difference in resistance is moni tored, the programmable controller 32 is activating the power system 31 to re direct the console 1 , thus attempting to re-establish equal light intensity at every photo sensor 323b.

[0036] In an alternative embodiment (see figure 5b), each photo sensor 323b is slanted, i.e. a centre axis 323c of each photo sensor 323b not coinciding with a plane per pendicular to a base of the photo sensor array 323, the direction of the slanting of each sensor centre axis being rotated in accordance with the angular distance be tween the photo sensors 323b.

[0037] Reference is now made to figure 4. The power system in the form of a hydraulic system 31 comprises two first hydraulic cylinders 311 connected to a first direc tional valve 313a controlling the tilting of the console 1 , and a second hydraulic cylinder 312 connected to a second directional valve 313b controlling the rotation of the console 1. Each directional valve 313a, 313b is provided with means for controlling the speed of the respective cylinders 311 , 312, here shown as adjusta- ble restrictors. The tilting and rotating speed is preferably set to allow the reposi tioning of the console 1 to be finished within a predefined time interval such as 30 seconds.

[0038] A hydraulic pump 313c provides a required oil flow and oil pressure to the direc- tional valves 313a, 313b controlled by the programmable controller 32 monitoring the oil pressure by a pressure sensor 313g. Furthermore, an accumulator 313d arranged to maintain the oil pressure over time is integrated in the hydraulic sys tem 31. The accumulator 313d, which may include a not shown bladder including a fluid with a higher thermal expansion coefficient than the hydraulic control fluid, is preferably exposed to the sunlight LSI causing the hydraulic pressure, due to heating, to increase over time, thus reducing the hours of operation of the hydrau lic pump 313c. A safety valve 313h is arranged to bleed off over-pressure to an oil reservoir 313e. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many al ternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be con strued as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0039] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

C l a i m s1. A system for automatic directional adjustment of a console (1 ) relative to the sun’s (LS) position, comprising a power system (31) comprising a power unit (313), a tilting actua tor (311 ) and a rotation actuator (312) arranged to tilt and rotate the con sole (1), respectively, and a control system (3) arranged to control the power unit (313), the tilting actuator (311), and the rotation actuator (312), c h a r a c t e r i s e d i n that the control system (3) comprises a programmable controller (32) connected to an array (323) of photo sensors (323b); the control system (3) being arranged to equalize a light intensity at each of the photo sensors (323b) by facing the array (323) of photo sensors (323b) towards the light source (LS) through tilting and rotation of the console (1).

2. The system according to claim 1 , wherein the programmable controller (32) comprises a programmable logic controller (PLC) (321) and a propor tional-integral-derivative (PID) controller (322).

3. The system according to claim 1 or 2, wherein the photo sensors (323b) are photoresistors.

4. The system according to any one of the preceding claims, wherein the ar ray (323) of photo sensors (323b) comprises four photo sensors (323b) distributed about an array centre axis (323a).

5. The system according to any one of the preceding claims, wherein adja cent photo sensors (323b) are separated by light-proof panels (323d) that are arranged to shade one or more narrow-spaced photo sensors (323b) if a centre axis (323a) of the array (323) of photo sensors (323b) is not coin ciding with incident light (LSI) from the sun (LS).

6. The system according to any one of the claims 1-4, wherein each photo sensor (323b) is distributed about an array centre axis (323a), a centre ax-is (323c) of each photo sensor (323b) being oriented at an angle relative the array centre axis (323a).

7. The system according to any one of the preceding claims, wherein the power system (31) is a hydraulic system, wherein the power unit (313) comprises a hydraulic pump (313c) and directional valves (313a, 313b) ar ranged to control a first hydraulic cylinder (311 ) and a second hydraulic cylinder (312).

8. The system according to claim 7, wherein the hydraulic system (31) is hy draulically connected to an accumulator (313d) exposable to incident light (LSI) from the sun (LS) and so as to affect a hydraulic pressure in the hy draulic system (31).

9. The system according to claim 8, wherein the accumulator includes a fluid with a higher thermal expansion coefficient than that of the hydraulic con trol fluid.

10. The system according to any one of the preceding claims, wherein the programmable controller (32) is arranged to redirect the console (1) at ad justable intervals.

11. The system according to any one of the preceding claims, wherein the power system (31) is arranged with means (313f) for preadjusting the tilt- ing and rotation speed of the console (1 ).

12. The system according to any one of the preceding claims, wherein the programmable controller (32) is arranged to redirect the console (1) to an appropriate sunrise position after sunset according to previously registered hour and altitude of sunset and sunrise.

13. The system according to any one of the preceding claims, wherein the ar ray of photo sensors (323) is attached to the console (1 ).

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