WO2009031726A1

WO2009031726A1 - A sun following sensor unit and a sun following apparatus having the same therewith

Info

Publication number: WO2009031726A1
Application number: PCT/KR2007/005354
Authority: WO
Inventors: Joo-Pyoung Yoon
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-09-03
Filing date: 2007-10-29
Publication date: 2009-03-12
Anticipated expiration: 2010-03-03
Also published as: KR100898501B1; AU2007358713A1; KR20090023765A; JP2011512017A; US20100192940A1; EP2191208A1

Abstract

The present invention relates to a sun tracking sensor unit and a sun tracking apparatus having the same. There is provided a sun tracking apparatus, which comprises a sun tracking sensor unit 10 comprising an upright barrier 12 for partitioning a sensor case into four specific areas of east, west, south and north, CDS elements CDS(E), CDS(W), CDS(S), and CDS(N) respectively disposed in the four areas partitioned by the upright barrier 12, and the sensor case 11 functioning as a body for supporting the upright barrier and the CDS elements; a solar panel combination 20 including a solar panel 22 having a plurality of solar cells attached thereon and a solar support body 24 coupled to a rear thereof; a housing 30 functioning as a body for supporting the sun tracking sensor unit 10 and the solar panel combination 20; and an east-west driving motor 40 and a south-north driving motor 50, coupled to the housing to adjust an angle of the solar panel by rotating the solar support body respectively in east- west and south-north directions. Accordingly, its tracking accuracy is high due to the lower limit of trackable illumination intensity, and its whole structure is simple, thereby having a low manufacturing and maintenance cost.

Description

A SUN FOLLOWING SENSOR UNIT AND A SUN FOLLOWING APPARATUS HAVING THE SAME THEREWITH

Technical Field

[1] The present invention relates to a sun tracking sensor unit and a sun tracking apparatus having the same, and more particularly, to a sun tracking sensor unit, which has a high tracking accuracy since the lower limit of trackable illumination intensity is low and is simple in whole structure, and a sun tracking apparatus having the sun tracking sensor unit.

[2] Specifically, in the present invention, characteristics of a cadmium sulfide (CDS) photoconductive cell are used in sun tracking. That is, the characteristics of the CDS photoconductive cell include a characteristic in which its internal resistance is decreased when the CDS photoconductive cell receive various types of beams such as sunbeams and a characteristic of a bridge circuit, i.e., a characteristic in which current flows by passing through a middle portion of the bridge circuit when resistance unbalance exists between resistors arranged in a diamond pattern. Background Art

[3] As exhaustion of petroleum energy and environmental pollution are recognized as serious problems of the whole human beings, all the countries of the world have made every effort to develop alternative energy.

[4] Solar energy is the most representative example of alternative energies to be developed or researched. The solar energy is collected by allowing a solar panel having a plurality of solar cells attached thereon to be directed to the sun, wherein the solar cell has a characteristic, in which current is generated when the sunlight is received, i.e., photoelectric effect.

[5] Such solar energy collecting mechanism is a fundamental principle of an apparatus using solar energy as an alternative energy. In a technical field related to the solar energy, studies have been actively conducted to collect a maximum amount of solar energy.

[6] In order to collect the maximum amount of solar energy, the movement of the sun is basically tracked using a separate sensor unit so that the solar panel is continuously directed toward the sun in the daytime.

[7] A sensor unit for tracking the movement of the sun is a sun tracking sensor unit. A conventional sun tracking sensor unit comprises four optical sensors for respectively sensing solar illumination intensities at specifically partitioned areas, i.e., east, west, south and north areas; one optical sensor for sensing a total solar illumination intensity; and a computer controller for receiving information of values sensed from these optical sensors to calculate a quantity required in adjusting an angle of a solar panel and to provide a control command.

[8] A conventional sun tracking apparatus has a sun tracking sensor unit provided with the aforementioned structure, and mainly comprises a motor driver operating in accordance with control commands provided from the sun tracking sensor unit.

[9] However, the conventional sun tracking sensor unit and sun tracking apparatus have some fundamental problems.

[10] First, since the unit sensors of the sun tracking sensor unit do not sense and track the sunlight having a critical illumination intensity or less, it is impossible to track and collect the sunlight in a cloudy day. Further, when the sun is covered by the clouds for a long time and then reappears therefrom, great confusion is caused in the sun tracking, which additionally requires the manual operation.

[11] In addition, computer equipment is expensive, which operates program for calculating a quantity required in adjusting the angle of a solar panel using signal values received from the sun tracking sensor unit as input data. Disclosure of Invention

[12] The present invention is conceived to solve the problems in the prior art. An object of the present invention is to provide a well configured sun tracking sensor unit having a high tracking accuracy due to the lower limit of trackable illumination intensity, and a sun tracking apparatus having the sun tracking sensor unit.

[13] In addition, another object of the present invention is to provide a sun tracking sensor unit having a simple whole structure and a low manufacturing and maintenance cost, and a sun tracking apparatus having the sun tracking sensor unit.

[14] These objects of the present invention are achieved by providing a sun tracking sensor unit using cadmium sulfide (CDS) photoconductive cells (hereinafter, referred to as "CDS elements") as unit sensors and by providing a circuit for controlling an angle of a solar panel having bridge circuits provided with the CDS elements.

[15] More specifically, a sun tracking sensor unit according to the present invention comprises an upright barrier for partitioning a sensor case into four specific areas of east, west, south and north; CDS elements respectively disposed in the four areas partitioned by the upright barrier; and the sensor case functioning as a body for supporting the upright barrier and the CDS elements.

[16] In addition, a sun tracking sensor unit according to the present invention comprises the sun tracking sensor unit having the aforementioned characterized configuration; a solar panel combination including a solar panel having a plurality of solar cells attached thereon and a solar support body coupled to a rear thereof; a housing functioning as a body for supporting the sun tracking sensor unit and the solar panel combination; and an east- west driving motor and a south-north driving motor, coupled to the housing to adjust an angle of the solar panel by rotating the solar support body respectively in east- west and south-north directions.

[17] The characteristics of the solar tracking apparatus according to the present invention is summarized in that there is provided the sun tracking sensor unit comprising the CDS elements respectively disposed in the four specific areas partitioned by the upright barrier and there is provided the circuit for controlling an angle of the solar panel comprising two bridge circuits respectively having two CDS elements corresponding to each other, which are disposed separately in the east- west or south-north.

[18] The principle of the sun tracking apparatus having the aforementioned configuration that automatically operates will be described below.

[19] First, while the sun rises from the east and moves to the west, there is a difference in brightness, i.e., illumination intensity of sunbeams thrown on an east CDS element, a west CDS element, a south CDS element and a north CDS element, which are respectively disposed at corresponding areas as unit sensors of the sun tracking sensor unit.

[20] The reason why the illumination intensities on the CDS elements corresponding to each other are different is that the shadow of an upright barrier disposed between the CDS elements is cast on any one of the CDS elements.

[21] The reason why the illumination intensity difference is generated not only between the east and west CDS elements but also between the south and north CDS elements is that the sun is practically inclined slightly to the south when the sun rises from the east and moves to the west (the sun is more inclined in winter as compared with in summer).

[22] When the illumination intensity difference is generated between the CDS elements, a resistance unbalance phenomenon, in which the internal resistance of a CDS element at a brighter side is lower than that of a CDS element at the opposite side, and accordingly, a voltage unbalance phenomenon occur.

[23] Here, when the two CDS elements corresponding to each other constitute a bridge circuit in which they are disposed at the same point on different branch lines, and current flows into the bridge circuit, current passing across a middle portion of the bridge circuit (hereinafter, referred to as "unbalanced current") flows due to the internal resistance unbalance between the CDS elements and the voltage unbalance between the branch lines including the CDS elements.

[24] In the present invention, the operation of an east- west driving motor or south-north driving motor is controlled using the intensity of the unbalanced current generated due to the internal resistance unbalance between the two CDS elements corresponding to each other as a signal value, thereby allowing the solar panel to be continuously directed to the sun.

[25] In other words, if the solar panel is positioned inclined with respect to the sun, the shadow of the upright barrier is cast over any one of the two CDS elements corresponding to each other, which constitute the bridge circuit. Accordingly, unbalanced current passing across the middle portion of the bridge circuit flows, and the east- west driving motor and/or a south-north driving motor operate using the unbalanced current as a signal value, so that the solar panel is rotated to a direction in which the unbalanced current is removed (a direction in which the shadow of the upright barrier is not cast over any one of the CDS elements as the CDS elements are straightly directed to the sun).

[26] Meanwhile, when the solar panel is completely rotated to the west at sunset, a limit switch and a timer at a corresponding point operate. Accordingly, when a certain period of time elapses, the east- west driving motor re-operates so that the solar panel returns to the east.

[27] For reference, in the sun tracking sensor unit according to the present invention, the

CDS element, as a unit sensor, has a change in internal resistance even with respect to a considerably weak light. While a conventional sun tracking sensor unit does not properly operate in an illumination intensity state of below 10000 LUX, the sun tracking sensor unit according to the present invention precisely operates even in an illumination intensity state of about 300 LUX, thereby having tracking accuracy considerably superior to that of the conventional sun tracking sensor unit. Brief Description of Drawings

[28] Fig. 1 is a front sectional view showing an east- west tracking sensor unit constituting a sun tracking sensor unit according to an embodiment of the present invention;

[29] Fig. 2 is a front view showing a sun tracking apparatus according to an embodiment of the present invention;

[30] Fig. 3 is a right side view showing the sun tracking apparatus according to the embodiment of the present invention;

[31] Fig. 4 is a left side view showing the sun tracking apparatus according to the embodiment of the present invention;

[32] Fig. 5 is a partial sectional view showing a mutual coupling relation between a solar support body and an upper connection body, which constitute the sun tracking apparatus according to the embodiment of the present invention;

[33] Fig. 6 is a partial sectional view showing a mutual coupling relation between an upper support body and a connection body, which constitute the sun tracking apparatus according to the embodiment of the present invention; [34] Figs. 7 and 8 are partial circuit diagrams showing a circuit for controlling an east- west angle of a solar panel in the sun tracking apparatus according to the embodiment of the present invention (they are interconnected through three points A, B and C on these figures); and

[35] Figs. 9 to 10 are partial circuit diagrams showing a circuit for controlling a south- north angle of the solar panel in the sun tracking apparatus according to the embodiment of the present invention (they are interconnected through three points A, B and C on these figures).

[36] [Explanation of Reference Numerals for Major Portions Shown in Drawings]

[37] 10: Sun tracking sensor unit 11: Sensor case

[38] 12: Upright barrier 13: Cover

[39] CDS(E): East CDS element CDS(W): West CDS element

[40] CDS(S): South CDS element CDS(N): North CDS element

[41] 20: Solar panel combination 22: Solar panel

[42] 24: Solar support body 30: Housing

[43] 31: Support body 32: Connection body

[44] 40: East-west driving motor 50: South-north driving motor

[45] 60: Storage battery 70: Control box

Best Mode for Carrying out the Invention

[46] Hereinafter, a sun tracking sensor unit and a sun tracking apparatus according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[47] Fig. 1 is a front sectional view showing an east- west tracking sensor unit 10-1 constituting a sun tracking sensor unit according to an embodiment of the present invention. The east- west tracking sensor unit 10-1 comprises an upright barrier 12 for partitioning a sensor case 11 into both east and west areas; CDS elements, i.e., an east CDS element CDS(E) and a west CDS element CDS(W), respectively disposed in the specific areas partitioned by the upright barrier 12; and the sensor case 11 functioning as a body for supporting the CDS elements and the upright barrier 12.

[48] The sensor case 11 is a cylinder having a top-opened sidewall with an appropriate height of about 30 mm, at which integral sidelight projected onto the CDS elements CDS(E) and CDS(W) can be blocked. The top of the cylinder is covered by a cover 13 made of a transparent or translucent plate material, such as glass or acrylic.

[49] Preferably, the cover 13 is made of a glass material whose color is changed depending on the brightness of light, considering that the CDS elements are considerably sensitive to light because of their material characteristics.

[50] The upright barrier 12 is made of an opaque material which casts its shadow over the CDS elements CDS(E) and CDS(W) attached on a bottom surface of the sensor case.

[51] Meanwhile, in the illustrated embodiment, an east- west tracking sensor unit and a south-north tracking sensor unit are separately formed by dividing the upright barrier 12 into a barrier for east- west partitioning and a barrier for south-north partitioning and allowing the barriers to be respectively disposed in separate sensor cases 11. However, all the functions of the east- west tracking sensor unit and the south-north tracking sensor unit may be implemented in one sensor case by forming the upright barrier in an X shape for east- west-south-north partitioning and allowing CDS elements to be disposed in the respective areas.

[52] Referring to Fig. 2, which shows a front view of a sun tracking apparatus according to an embodiment of the present invention, a solar tracking apparatus 20 comprises the solar tracking sensor unit 10 having the aforementioned configuration; a solar panel combination 20 including a solar panel 22 having a plurality of solar cells attached thereon and a solar support body 24 coupled to the rear thereof; a housing 30 functioning as a body for supporting the sun tracking sensor unit 10 and the solar panel combination 20; and an east-west driving motor 40 and a south-north driving motor 50, coupled to the housing to adjust an angle of the solar panel 22 by rotating the solar support body 24 in east-west and south-north directions.

[53] The housing 30 is configured in the form of a combination of a support body 31 and a connection body 32. While the support body 31 defining a lower end of the housing 30 is fixed to a ground or platform (not shown), the connection body 32 defining an upper end thereof serves to connect the solar support body 24 to the support body 31.

[54] The support body 31 is configured in the form of a combination of a lower support body 31-1 fixed directly to the ground or the like and an upper support body 31-2 providing a mutually coupling portion to the connection body 32.

[55] The lower support body 31-1 is formed with horizontal plates respectively welded to both upper and lower ends of a quadrangular steel tube. In the sun tracking apparatus according to the embodiment of the present invention, various types of wires constituting a circuit for controlling an angle of the solar panel pass through the interior of the lower support body.

[56] The upper support body 31-2 has two bent plates coupled to the upper end of the lower support body 31-1. The bent plates are spaced apart from each other at a predetermined interval to define a vertical gap, and a vertical plate- shaped lower end of the connection body 32 is inserted into the gap.

[57] In addition, the upper support body 31-2 and the lower end of the connection body 32 are coupled to each other through a rotation shaft of the south-north driving motor 50, which makes a relative rotary motion possible.

[58] Meanwhile, a storage battery 60 and a control box 70 are coupled to the support body 31 constituting the housing 30.

[59] In the sun tracking apparatus 100 of the present invention, the storage battery 60 is an essential component for controlling an angle of the solar panel as described above, while the control box 70 serves as a container in which various types of electric elements constituting the circuit for the control are accommodated.

[60] The sun tracking apparatus 100 as configured above rotates from east to west, i.e., in a direction of the arrow, at the same time when the sun rises. The rotation is performed about a rotation shaft of the east- west driving motor 40 by the operation thereof.

[61] The configuration of the circuit for controlling an angle of the solar panel will be described together with the detailed operation of the sun tracking apparatus 100 according to the embodiment of the present invention.

[62] Unexplained reference numeral B designates a bolt for fixing a driving motor or the like.

[63] Fig. 3 is a right side view showing the sun tracking apparatus according to the embodiment of the present invention.

[64] A support plate 23 is coupled to a rear surface of the solar panel 22 to which the plurality of solar cells are directly attached, and the solar support body 24 of a U- shaped bent plate is welded to the rear surface of the support plate 23, so that they are formed in a single body.

[65] Like the aforementioned support body 31, the connection body 32 comprises an upper connection body 31-1 and a lower connection body 32-2 welded to a lower end thereof. While the upper connection body 32- 1 is a U-shaped bent plate, the lower connection body 32-2 is formed in the shape of a vertical plate.

[66] A lower end of the U-shaped solar support body 24 is inserted into a U-shaped internal space of the upper connection body 32-1.

[67] In addition, the upper connection body 32-1 and the solar support body 24 are coupled to each other through a rotation shaft of the east- west driving motor 40, which makes a relative rotary motion possible.

[68] Unexplained reference numeral N designates a nut for fixing the support plate 24.

[69] Fig. 4 is a left side view showing the sun tracking apparatus according to the embodiment of the present invention, which is used to illustrate a mounting state of the sun tracking sensor unit 10, or a south inclination of the solar panel 22.

[70] As shown in this figure, the sun tracking sensor unit 10 comprises an east- west tracking sensor unit 10-1 and a south-north tracking sensor unit 10-2. The internal structure of the east- west tracking sensor unit 10-1 is identical to that of the south- north tracking sensor unit 10-2, except that the aforementioned two upright barriers are vertically or horizontally disposed respectively.

[71] As discussed again, the X-shaped upright barrier is used, so that the east- west tracking sensor unit 10-1 and the south-north tracking sensor unit 10-2 can be implemented in a single sensor case. Accordingly, the sun tracking sensor unit of the present invention should not be limited to a structure in which it is divided into sensor units for east- west tracking and south-north tracking.

[72] As the east- west driving motor 40 operates, the solar panel 22 having the plurality of solar cells 21 attached thereon in line rotates from east to west while tracking the sun. Practically, the solar panel rotates from east to west while maintaining a state where it is slightly inclined to the south.

[73] This is because the sun, which is only an object to be tracked, rotates along such a trace. The inclining operation (in a direction of the arrow) of the solar panel 22 for tracking the south inclination of the sun is performed based on the rotation of the south-north driving motor (point P).

[74] Fig. 5 is a partial sectional view showing a mutual coupling relation between the solar support body and the upper connection body (see Fig. 3).

[75] Two steel tubes T respectively welded and coupled to both sidewalls of the solar support body 24 while passing through both the sidewalls are supported by the upper connection body 32-1. As bearings Br are mounted at the support portions, a relative rotary motion between the members is implemented.

[76] As shown in this figure, the left side of the solar support body 24 is directly supported by the upper connection body 32-1, while the right side of the solar support body 24 is supported by an additional round bar-shaped support shaft S, which is welded while passing through the center of the plate.

[77] As the steel tube T adjacent to the east-west driving motor 40 is fixedly coupled to the rotation shaft of the east- west driving motor 40 through a key K formed on an inner circumferential surface thereof, the rotating force of the east- west driving motor is transmitted to the entire solar panel combination via the solar support body 24 and the support plate 23.

[78] Considering that a rotary motion at a corresponding portion is very slowly performed and the supporting load at the corresponding portion is not excessive, it is reasonable that the bearing Br is not a typical ball bearing but a bush.

[79] Further, considering that the rotation of a motor is typically very fast, a decelerator R is mounted at the right side of the east- west driving motor 40.

[80] The bearing and the decelerator are identically applied to the south-north driving motor 50.

[81] Fig. 6 is a partial sectional view showing a mutual coupling relation between the upper support body and the connection body (see Fig. 2).

[82] Outer ends of a steel tube T welded while passing through a lower end of the connection body 32 are respectively supported by both the left and right bent plates constituting the upper support body 31-2. As bearings Br are mounted at the support portions, a relative rotary motion between the members is implemented.

[83] As shown in this figure, an outer end of the left one of the bent plates is welded and closed by an additional plate, thereby preventing the bearing Br from escaping.

[84] The steel tube T is fixedly coupled to the rotation shaft of the south-north driving motor 50 through the key K.

[85] Preferably, the whole components except the south-north driving motor 50 and the key K, i.e., the upper support body 31-2 and the connection body 32 are assembled, and then, the rotation shaft of the south-north driving motor 50 is inserted.

[86] Figs. 7 and 8 are partial circuit diagrams showing a circuit for controlling an east- west angle of the solar panel in the sun tracking apparatus according to the embodiment of the present invention, wherein they are interconnected through three points A, B and C on these figures.

[87] The operational mechanism of the east- west tracking sensor unit and the east-west driving motor, i.e., an angle controlling system of the solar panel will be described below with reference to the circuit diagrams.

[88] A bridge circuit, which is a basic component of the sun tracking apparatus according to the present invention, is shown in an upper region of Fig. 7. The two CDS element corresponding to each other, i.e., the east CDS element CDS(E) and the west CDS element CDS(W) are disposed at the same position on different branch lines ΓJ and g, at a side of a current inlet terminal (point a) on the bridge circuit.

[89] A variable resistor disposed just next to each of the CDS elements CDS(E) and

CDS(W) offsets resistance unbalance between the CDS elements, caused under mass production, so that the exact same resistance is formed between points a and b and between points a and c.

[90] Fixed resistors adjacent to a current outlet terminal (point d) are elements basically necessary for forming the bridge circuit.

[91] In addition, a branch line r that allows middle points on the two branch lines £ and cj. constituting the bridge circuit to be connected to each other is divided into two sub- branch lines, and then, diodes Dl and D2 are disposed on the sub-branch lines, respectively.

[92] As shown in the figure, the diodes Dl and D2 have directions opposite to each other so as to detect currents flowing in opposite directions to each other.

[93] A rectifying circuit is disposed just below the bridge circuit. AC 220 V is converted into about DC 240 V via the rectifying circuit comprising a bridge diode BD and an electrolytic capacitor (a portion designated by 350 V and 33 μF).

[94] An AC input unit (a portion designated by AC 220 V) shown at a lower portion of the circuit diagram is connected to an inverter (not shown) that converts DC current into AC current. The inverter is also connected to the storage battery (reference numeral 60 in Figs. 3, 4 and 5) that is a storage place of solar energy collected from the solar cells on the solar panel.

[95] Meanwhile, allowing DC power from the storage battery not to immediately flow into the bridge circuit but to flow along an additional path including the inverter and the rectifying circuit is to secure a wide voltage displacement range.

[96] In other words, the illustrated circuit diagram is only an embodiment showing the angle controlling system of the solar panel in the sun tracking apparatus according to the present invention. The present invention is not necessarily limited thereto.

[97] If an illumination intensity difference between the east CDS element CDS(E) and the west CDS element CDS(W) is generated when DC current flows into the bridge circuit so configured, the current flows from the point b to the point c or from the point c to the point b, i.e., the aforementioned unbalanced current flows due to the aforementioned characteristics of the bridge circuit.

[98] When the unbalanced current flows from the point c to the point b, the illumination intensity on the west CDS element CDS(W) is lower than that on the east CDS element CDS(E).

[99] This is because the shadow of the upright barrier is cast over the east CDS element

CDS(E) as the sun is more inclined toward the west as compared with the direction in which the east- west tracking sensor unit is directed.

[100] The unbalanced current flowing from the point c to the point b is detected by the diode D2 and flows into an OP amplifier AMP2 through connection points A and B via a photo coupler PC shown in Fig. 8.

[101] The current flowing into the OP amplifier AMP2 is subjected to a self-amplifying process and then drives a west relay CR2.

[102] As the west relay CR2 operates, a west magnet switch MC2 operates, which as a result, causes an east- west driving motor Ml to rotate clockwise (based on the rotational direction of the east- west driving motor in Fig. 3).

[103] As the east-west driving motor Ml rotates clockwise, the entire solar panel combination rotates to the west (to a point at which the sun is currently positioned), and the east- west tracking sensor unit mounted on the front surface of the solar panel is precisely directed to the sun.

[104] When the east- west tracking sensor unit is precisely directed to the sun, the illumination intensity on the east CDS element CDS(E) is identical to that on the west CDS element CDS(W). Consequently, internal resistances of the CDS elements are balanced, and accordingly, the unbalanced current does not flow any more.

[105] With the operational mechanism as described above, the east- west tracking sensor unit precisely tracks the movement of the sun to the west. [106] Assuming that the sun is more inclined toward the east as compared with the direction in which the east- west tracking sensor unit is directed although a considerably unusual situation, the unbalanced current flows from the point b to the point c on the bridge circuit. The unbalanced current is detected by the diode Dl and flows into an OP amplifier AMPl through connection points A and B via the photo coupler PC shown in Fig. 8.

[107] The current flowing into the OP amplifier AMPl passes through a self-amplifying process and then drives an east relay CRl.

[108] As the east relay CRl operates, an east magnet switch MCl operates, which as a result, causes the east- west driving motor Ml to rotate counterclockwise (see Fig. 3).

[109] Accordingly, the east-west tracking sensor unit is also directed to the sun, i.e., its angle is adjusted to the east.

[110] In addition, at the time when the sun sets after completely moving to the west, the solar panel combination causes a west limit switch Ll to operate, and at the same time, a timer T operates.

[I l l] If a time set on the timer T elapses, a west limit relay CR3 operates, and the west magnet switch MCl operates to drive the west limit relay CR3. As a result, the east- west driving motor Ml is driven counterclockwise, so that the solar panel combination returns to the east.

[112] At the time when the solar panel completely returns to the east, an east limit switch L2 operates, and an east limit relay CR4 simultaneously operates.

[113] Meanwhile, it will be understood by those skilled in the art that the position and the installation method of the limit switch, which operates simultaneously at the time when the solar panel reaches an east or west boundary point, can be variously implemented.

[114] For reference, unexplained reference numeral D designates a light emitting diode for indicating a direction of current, i.e., whether current flows to the east or the west. It will be apparent that if the light emitting diode is not necessary, it may be removed from the circuit.

[115] Figs. 9 to 10 are partial circuit diagrams showing a circuit for controlling a south- north angle of the solar panel in the sun tracking apparatus according to the embodiment of the present invention, in which they are interconnected through three points A, B and C on these figures.

[116] Considering that the sun tracking is performed depending on one of the CDS elements corresponding to each other, over which the shadow of the upright barrier is cast, a control mechanism of the south-north driving motor is identical to that of the east- west driving motor in a basic principle.

[117] Comparing the figures, Figs. 9 and 10 are substantially identical to Figs. 7 and 8 except that the east CDS element CDS(E), the west CDS element CDS(W) and the east- west driving motor Ml are replaced by a south CDS element CDS(S), a north CDS element CDS(N) and a south-north driving motor M2, respectively.

[118] In other words, the components related to the east/west in Figs. 7 and 8 are replaced by the components related to the south/north in Figs. 9 and 10.

[119] However, in the control mechanism of the south-north driving motor, it is not necessary to allow the solar panel combination to completely return to the east together with the operation of the timer when the sun sets, as in the control mechanism of the east- west driving motor. Therefore, the components related to Fig. 7, i.e., T, CR3, CR4 and the like do not exist in Fig. 9.

[120] However, considering that a rotation range of the south-north driving motor is necessarily limited for a case such as a trouble, a south limit switch L(3) and a north limit switch L(4) are disposed as relative elements. Industrial Applicability

[121] As described above, according to the present invention, there are provided a sun tracking sensor unit and a sun tracking apparatus having the same, wherein CDS elements that are very sensitive to light are used as unit sensors, so that its tracking accuracy is high and its whole structure is simple, thereby having a low manufacturing and maintenance cost.

[122] As petroleum resources are gradually exhausted, the international petroleum price is also increased. Accordingly, the present invention can be variously applied to industrial fields using solar energy as a main alternative energy.

[123]

Claims

[1] A sun tracking sensor unit (10), comprising: an upright barrier (12) for partitioning a sensor case into four specific areas of east, west, south and north;

CDS elements (CDS(E), CDS(W), CDS(S), CDS(N)) respectively disposed in the four areas partitioned by the upright barrier (12); and the sensor case (11) functioning as a body for supporting the upright barrier and the CDS elements.

[2] The sun tracking sensor unit (10) as claimed in claim 1, wherein the upright barrier (12) comprises a barrier for east- west partitioning and a barrier for south- north partitioning, and the barriers are respectively disposed in the separate sensor cases (11).

[3] The sun tracking sensor unit (10) as claimed in claim 1, wherein the upright barrier (12) is formed in an X shape for east- west-south-north partitioning and disposed in the single sensor case (11).

[4] The sun tracking sensor unit (10) as claimed in claim 2 or 3, wherein a top of the sensor case (11) is covered by a cover (13) made of a transparent or translucent plate.

[5] The sun tracking sensor unit (10) as claimed in claim 4, wherein the cover (13) is made of a glass material whose color is changed depending on brightness of light.

[6] A sun tracking apparatus (100), comprising: a sun tracking sensor unit (10) comprising an upright barrier (12) for partitioning a sensor case into four specific areas of east, west, south and north, CDS elements (CDS(E), CDS(W), CDS(S), CDS(N)) respectively disposed in the four areas partitioned by the upright barrier (12), and the sensor case (11) functioning as a body for supporting the upright barrier and the CDS elements; a solar panel combination (20) including a solar panel (22) having a plurality of solar cells attached thereon and a solar support body (24) coupled to a rear thereof; a housing (30) functioning as a body for supporting the sun tracking sensor unit

(10) and the solar panel combination (20); and an east-west driving motor (40) and a south-north driving motor (50), coupled to the housing to adjust an angle of the solar panel by rotating the solar support body respectively in east-west and south-north directions.

[7] The sun tracking apparatus (100) as claimed in claim 6, wherein a storage battery

(60) and a control box (70) are coupled to a support body (31) of the housing (30).

[8] The sun tracking apparatus (100) as claimed in claim 6, wherein the housing (30) comprises a support body (31) defining a lower end thereof and fixed to a ground or platform, and a connection body (32) defining an upper end thereof and connecting the solar support body (24) to the support body (31).

[9] The sun tracking apparatus (100) as claimed in claim 8, wherein the support body (31) comprises a lower support body (31-1) formed by respectively welding horizontal plates to both upper and lower end of a quadrangular steel tube and an upper support body (31-2) having two bent plates coupled to an upper end of the lower support body (31-1); and the connection body (32) comprises an upper connection body (31-1) of a U-shaped bent plate, and a lower connection body (32-2) formed in a vertical plate shape welded to a lower end of the upper connection body (31-2).

[10] The sun tracking apparatus (100) as claimed in claim 8 or 9, wherein the solar support body (24) is a U-shaped bent plate; a lower end thereof is inserted into a U-shaped internal space of the upper connection body (32-1); and the upper connection body (32-1) and the solar support body (24) are coupled to each other through a rotation shaft of the east- west driving motor (40), which makes a relative rotary motion possible.

[11] The sun tracking apparatus (100) as claimed in claim 8 or 9, wherein the two bent plates constituting the upper support body (31-2) are spaced apart from each other at a predetermined interval to define a vertical gap; a vertical plate-shaped lower end of the connection body (32) is inserted into the gap; and the upper support body (32-1) and the lower end of the connection body (32) are coupled to each other through a rotation shaft of the south-north driving motor (50), which makes a relative rotary motion possible.

[12] The sun tracking apparatus (100) as claimed in claim 6, comprising a circuit for controlling an angle of the solar panel, the circuit comprising two bridge circuits, each bridge circuit having two CDS elements (CDS(E) and CDS(W), CDS(S) and CDS(N)) corresponding to each other, which are separately disposed to the east and west or the south and north among the four CDS elements (CDS(E), CDS(W), CDS(S), CDS(N)).

[13] The sun tracking apparatus (100) as claimed in claim 12, wherein the two CDS elements (CDS(E) and CDS(W), CDS(S) and CDS(N)) corresponding to each other are disposed at the same position on different branch lines (ΓJ and φ, i.e., at a side of a current inlet terminal (point a) on the bridge circuit; a branch line (r) that allows middle points on the two branch lines (ΓJ and φ to be connected to each other is divided into two sub-branch lines; and diodes (Dl, D2) are then disposed on the sub-branch lines, respectively.