Solar tracker, and method for operating same

Abstract

The present invention relates to a solar tracker and to a method for operating same, capable of controlling the azimuth and elevation in accordance with the changing portion of the sun in the celestial sphere by the diurnal motion and annual motion so as to enable solar energy collection apparatuses to track the travel of the sun for a long period of time. The solar tracker according to the present invention is provided with two rotating shafts which are responsible for the right ascension and declination, respectively, wherein the movements of the rotating shafts are not independent from each other. One rotating shaft moves in dependence on the other rotating shaft, wherein the dependent relationship is mechanically constrained according to the correlation between the diurnal motion and annual motion of the sun. As a result, the tracker of the present invention can track the diurnal motion of the sun with a single actuator and, at the same time, compensate the annual motion which changes in the meridian altitude according to the change of seasons. The solar tracker and the method for operating same in accordance with the present invention, enables the tracking of the diurnal motion and annual motion of the sun using one actuator, thereby maximizing solar power generation efficiency and reducing initial installation costs and maintenance costs.

1 . A solar tracker  1000 , comprising:
 a right ascension rotation shaft  100  installed in parallel with the Earth's rotation axis a 34  and configured to track a change in a right ascension a 11  occurring due to a diurnal motion of the Sun a 01 ;   a right ascension rotation actuator  200  configured to actuate the right ascension rotation shaft  100 ;   a declination rotation shaft  300  perpendicular to the right ascension rotation shaft  100  and configured to reciprocatingly rotate on a four season cycle to track a change in a declination a 12  occurring due to an annual motion of the Sun a 01 ; and   a declination actuation mechanism  400  configured to transfer a portion of rotational power generated when the right ascension rotation actuator  200  actuates the right ascension rotation shaft  100  to the declination rotation shaft  300  to allow the declination rotation shaft  300  to reciprocatingly rotate upwards and downwards, and comprising a one-way clutch  450  installed at one point in a power transfer path from the right ascension rotation actuator  200  to the declination rotation shaft  300  and configured to select and transfer a one-way rotation component of the rotational power to be transferred to the declination rotation shaft  300 .   
     
     
         2 . The solar tracker  1000  of  claim 1 , comprising:
 a reduction ratio adjuster  440  installed at one point in the power transfer path from the right ascension rotation actuator  200  to the declination rotation shaft  300  and configured to increase or decrease a rotation ratio to be transferred. 
 
     
     
         3 . The solar tracker  1000  of  claim 1 , comprising:
 a coupling  430  installed at one point in the power transfer path from the right ascension rotation actuator  200  to the declination rotation shaft  300  and configured to connect or block the rotational power to be transferred. 
 
     
     
         4 . The solar tracker  1000  of  claim 1 , wherein the declination actuation mechanism  400  comprises:
 a declination reducer  410  configured to receive driving power of the right ascension rotation actuator  200 , convert a rotation ratio, and output the converted rotation ratio; 
 a crank  421  attached to an output shaft of the declination reducer  410 ; 
 a rocker  422  fixed to the declination rotation shaft  300  and reciprocatingly rotating upwards and downwards at the Earth's rotational axial tilt a 05  based on the change in the declination a 12  occurring due to the annual motion of the Sun a 01 ; and 
 a connecting rod  423  connecting one end of the crank  421  to one end of the rocker  422  to form a four-bar linkage  420 , and configured to convert a rotational motion of the crank  421  to the reciprocating up and down rotational motion of the rocker  422 . 
 
     
     
         5 . The solar tracker  1000  of  claim 4 , wherein the crank  421 , the rocker  422 , or the connecting rod  423  comprises an adjuster  424  configured to adjust a location of a joint or a link length to change a motional displacement and a sectional speed of the reciprocating up and down rotational motion of the declination rotation shaft  300 . 
     
     
         6 . The solar tracker  1000  of  claim 1 , comprising:
 a declination display device  460  configured to convert an amount of rotation of the declination rotation shaft  300  to an angle and display the angle; or 
 a solar term display device  470  configured to convert the amount of rotation to a solar term a 40  of a year and display the solar term a 40 . 
 
     
     
         7 . A method of operating a solar tracker  1000 , comprising:
 a first operation S 01  to match a direction of a right ascension rotation shaft  100  to the Earth's rotation axis a 34 ;   a second operation S 02  to match an angle of a declination rotation shaft  300  to a declination a 12  of the Sun a 01 ;   a third operation S 03  to track a diurnal motion of the Sun a 01  by actuating the right ascension rotation shaft  100  by a right ascension rotation actuator  200 ; and   a fourth operation S 04  to track, by the declination rotation shaft  300 , a change in a meridian altitude a 23  of the Sun a 01  occurring due to an annual motion, by allowing a declination actuation mechanism  400  to selectively extract a one-way rotation component and allow the declination rotation shaft  300  to reciprocatingly rotate on a four season cycle when the declination actuation mechanism  400  transfers a portion of driving power of the right ascension rotation actuator  200  to the declination rotation shaft  300 .   
     
     
         8 . The method of  claim 7 , comprising any one of:
 a fifth operation S 05  to change a motional displacement of the declination rotation shaft  300  by adjusting the declination actuation mechanism  400  in response to the motional displacement of the declination rotation shaft  300  being less or greater than the Earth's rotational axial tilt a 05 ;   a sixth operation S 06  to change a motion cycle of the declination rotation shaft  300  by adjusting a reduction ratio adjuster  440  in response to the motion cycle of the declination rotation shaft  300  being longer or shorter than a cycle of revolution of the Earth a 02 ; and   a seventh operation S 07  to release a coupling  430  and reset an angle of the declination rotation shaft  300  in response to a large difference between the angle of the declination rotation shaft  300  and the declination a 12  of the Sun a 01 .   
     
     
         9 . The method of  claim 7 , wherein an angle at which the declination rotation shaft  300  reciprocatingly rotates upwards and downwards in the fourth operation S 04  corresponds to the Earth's rotational axial tilt a 05  in each of an upward direction and a downward direction. 
     
     
         10 . The solar tracker  1000  of  claim 1 , comprising:
 a balance weight  560  configured to adjust a weight and an attached location of a load to allow a centroid of the load applied to each rotation shaft to be positioned in each rotation shaft by changing the centroid of the load, in order to prevent a rotation by a self weight and minimize an amount of rotational power required for actuating a rotation shaft through a balance of the load applied to the right ascension rotation shaft  100  or the declination rotation shaft  300 .