[0012] The present invention will be further described in detail below in conjunction with the embodiments and drawings.
[0013] The solar position photoelectric sensor provided by the present invention has a structure such as Figure 1 to Figure 4 Shown: There is a precise tracking component inside and a rough tracking component outside; the precise tracking component is composed of a light-passing aperture 2 and a four-quadrant silicon photocell 5. The four-quadrant silicon photocell is placed on the base 6 of the sensor, and the light-through aperture is The optical class hole is located directly above the four-quadrant silicon photocell, and the center of the optical class hole and the origin of the four-quadrant silicon photocell are both located on the central axis of the sensor; the rough tracking component is composed of four ordinary silicon photocells 4, which are evenly distributed The sensor is on the outside of the inclined wall 3.
[0014] The distance between the center of the spot hole and the four-quadrant silicon photocell 5 is 19-21 mm, and 20 mm is recommended. The diameter of the spot hole is one-half of the diameter of the four-quadrant photovoltaic cell.
[0015] The inclined wall 3 is a trapezoidal platform, and the inclination angle of each hypotenuse is 75°. There are grooves with a symmetrical layout on each oblique side, and ordinary silicon photovoltaic cells 4 are embedded in them. The ordinary silicon photovoltaic cell 4 can be a cheap crystalline silicon photovoltaic cell on the market.
[0016] The four ordinary silicon photocells 4 are symmetrical in pairs and are respectively distributed on the X axis and Y axis of the four-quadrant silicon photocell 5. The X-axis of the four-quadrant silicon photovoltaic cell 5 after installation corresponds to the east-west direction, and the Y-axis corresponds to the north-south direction.
[0017] The working principle of the four-quadrant silicon photovoltaic cell 5 is that the current output on each quadrant of the four-quadrant silicon photovoltaic cell is linearly related to the light it receives. When the sun's spot illuminates the center of the four-quadrant silicon photovoltaic cell, that is, the center of the spot is at When the centers of the four-quadrant silicon photocells coincide, the four quadrants of the four-quadrant silicon photocells receive the same light energy and have the same output; when the sun moves, the incident angle changes, and the light spot shifts in the four-quadrant silicon photocell coordinate system , The current output of the quadrant that receives more light energy increases, and the current output of the quadrant that receives less light decreases, so as to determine the position of the sun. In order to achieve high precision, the precision tracking component of the solar position photoelectric sensor (sensor for short) must have little interference, so this precision tracking part adopts a structural design in which all parts except for the small spot hole are sealed and opaque. And achieving high-precision tracking of the sun is image 3 In the α angle range shown, when the angle between the incident sun and the axis of the sensor is small, the sensor can also complete the perception of the sun's position and prompt the precision tracking component to track the sun. And the smaller the angle, the better. Therefore, as long as the sensitivity of the four-quadrant silicon photocell is high enough and the sensitivity of the signal acquisition part to the signal is high enough, sufficient accuracy can be achieved. Such as Figure 4 As shown, the solar spot is on the X coordinate of the four-quadrant silicon photocell at this time, such as Figure 5 The distance between the center of the light spot and the center of the four-quadrant battery is ΔX=H·TAN(0.1°)=20·TAN(0.1°)=0.035(mm). For the convenience of calculation, the light spot can be similar to a square when the angle is small. When the light spot is shifted to the negative direction of the X coordinate, the current output deviation on both sides is the largest. The current output of the photovoltaic cell has a linear relationship with its light-receiving area, so the ratio of the current output deviation in the positive and negative directions of the four-quadrant silicon photovoltaic cell to the maximum current output deviation is 2ΔX·(R/2):∏(R/2) 2 = 0.045. And the most basic 8-bit ADC chip accuracy of the digital-to-analog conversion chip of the single-chip microcomputer reaches 1/2 8 , Much smaller than 0.045, so the signal acquisition and judgment fully meet the accuracy requirements. The general four-quadrant silicon photovoltaic cells on the market can also achieve this accuracy. The size of the α angle is determined by the effective light-receiving area of the four-quadrant silicon photovoltaic cell and the tracking H of the sensor's central light hole plate 2 and the four-quadrant silicon photovoltaic cell. If H is too large, the α angle will be small, and the precise tracking angle range will be too small, causing frequent switching between precise tracking and coarse tracking, causing system instability; if H is too small, the above ΔX will be small, which cannot guarantee the tracking accuracy. So choose H to be 20mm here.
[0018] Example: One morning the tracking system faces the east, but it is rainy and the tracking system stops working. When the sun comes out in the afternoon, the tracking system is activated. The sun's rays deviate from the sensor axis by a certain angle. When the angle is greater than 90 degrees, the general solar position sensor cannot detect the position of the sun, while the present invention can detect the position of the sun within 330 degrees. At this time, the deflection angle is greater than the precise tracking angle, that is, the four-quadrant photocell working angle range α, and the rough tracking program is started. At this time, the sun's rays can only illuminate the two ordinary silicon photocells on one side, so that the output current is relatively large, and the general position of the sun can be judged, and the tracking system can be controlled to rotate in the direction of the sun. When the incident angle of the sun is reduced to the other two ordinary silicon photocells at the same time, because the incident angle of the sun's rays on the cell is different, the absolute light energy is also different. The original two ordinary silicon photocells that received the light received the sun. The energy is still large, so the tracking system continues to roughly track towards the sun. When the angle between the sun's rays and the axis of the sensor is less than α, the internal four-quadrant silicon photocell receives sunlight and has a sudden increase in current output. A current threshold can be set, and when the current is greater than this threshold, it can be determined that the sun's incidence angle is already less than α. At this time, it enters the precise tracking stage, shields the signals of the four ordinary silicon photocells outside, and only processes the four quadrant current signals of the four-quadrant silicon photocells. At this time, the solar spot has a large offset origin in the four-quadrant coordinate system, and the current output of the battery in the quadrant where the center is located is large, and the position of the sun can be determined for accurate tracking. When the current output of the batteries on both sides of the same coordinate axis is less than a threshold, that is, the current difference at the minimum sun incidence angle that is set to ensure the tracking accuracy, the tracking can be judged to be completed. Wait for a period of time T before making judgments and then tracking to complete the continuous tracking of the sun's position.
[0019] The solar position photoelectric sensor (referred to as the sensor) provided by the present invention can calculate the distance between the center of the solar spot on the battery and the coordinate center of the four-quadrant silicon photocell by comparing the output current values of the four quadrants of the four-quadrant silicon photocell. By comparing the output current value of the four silicon photocells, the rough position of the sun can be obtained to complete the rough position detection; the single-chip microcomputer can be used to complete the signal processing of the rough position detection and the precise position detection and Logic processing between the two detections.
[0020] When the sensor provided by the present invention is used, it can be fixed on the top of the dual-axis sun tracking system, and its axis is perpendicular to the plane where the lens of the concentrating module is located. Such as image 3 Shown: the ordinary silicon photovoltaic cell 4 is inside the inclined wall 3, and the light-receiving surface of the cell faces outward. When the angle between the incident light and the central axis of the sensor is such as image 3 Outside of the β angle shown, at least one of the two ordinary silicon photovoltaic cells on the left and right can receive sunlight, that is, the sensor has a signal. Here β is 30°, so the maximum detectable angle of the ordinary silicon photocell 4 is 330°. Because the outside of the sensor is easily affected by interference light, the four ordinary silicon photocells 4 can only be used as a rough tracking sensor part. When the angle between the incident light and the center axis of the sensor is such as image 3 When the angle α is shown, the light can pass through the small holes in the light aperture plate 2 to irradiate the four-quadrant silicon photocell 5 to make it have a signal output, and then a position deviation signal can be obtained according to a certain algorithm to control the operation of the tracking mechanism.
