عنوان مقاله
طراحی سیستم ردیابی خورشیدی خودکار بر مبنای ARM
فهرست مطالب
مقدمه
اصول طراحی سیستم
طراحی سخت افزاری سیستم
طراحی نرم افزار سیستم
نتایج آزمایش
بخشی از مقاله
اصول طراحی سیستم
پرتوهای خورشید را می توان به دو مولفه تجزیه نمود، یکی عمود بر سطح صفحه نور خورشید و دیگری موازی با سطح، صفحه نور خورشید فقط قادر به دریافت تابش اول می باشد. بنابراین زاویه بین پرتوهای خورشید و نرمال صفحه ای که زاویه فرودیθ می باشد، باید تا حد امکان کوچک باشد. زاویه فرودθ نسبت به تغییر روزانه و تغییر فصلی تغییر می کند. بنابراین، کلکتورهای خورشیدی ثابت قادر به جذب کامل انرژی تابش خورشیدی نمی باشند.
کلمات کلیدی:
The design of ARM-based ARM-based ARM-based ARM-based automatic automatic automatic automatic sun tracking tracking tracking tracking system Xie Yuan Institute of Electrical Engineering and Automation TIANJIN POLYTECHNIC UNIVERSITY Tianjin,China E-mail: ganjiangshui@vip.qq.com Guo Wencheng Institute of Electrical Engineering and Automation TIANJIN POLYTECHNIC UNIVERSITY Tianjin,China E-mail: guowc@tjpu.edu.cn Abstract Abstract Abstract Abstract—This paper gives a design that using 32-bit ARM (Advanced (Advanced (Advanced (Advanced RISC Machines) Machines) Machines) Machines) embedded embedded embedded embedded microprocessor microprocessor microprocessor microprocessor chip as a controller, controller, controller, controller, to achieve achieve achieve achieve the automatic automatic automatic automatic sun tracking tracking tracking tracking by controlling controlling controlling controlling of the vertical vertical vertical vertical and horizontal horizontal horizontal horizontal two directions directions directions directions through through through through the program. program. program. program. Analyze Analyze Analyze Analyze the systematic systematic systematic systematic error and experiment, experiment, experiment, experiment, results results results resultsshow that: the method of tracking tracking tracking tracking accuracy accuracy accuracy accuracy can be up to the ±0.1° , in various various various various weather weather weather weather conditions. conditions. conditions. conditions. The tracker tracker tracker tracker system can steadily steadily steadily steadily work and achieve achieve achieve achieve the expected expected expected expected design performance. performance. performance. performance. Keywords- Keywords- Keywords- Keywords- ARM;CPLD; sun-tracking sun-tracking sun-tracking sun-tracking; solar energy ; I. INTRODUCTION Increasing depletion of world energy, the development and use of renewable energy has bright prospects, as the focus of future energy question. Solar energy is the most important renewable energy source with its total quantity is large, and occurs widely. Resource depletion problems do not exist. How fully and efficiently use of solar energy is a key. The conventional solar receiving devices are usually fixed, this installation is simple, structural stability, but because of the location of the sun in the sky is changing, most of the time the sun can not direct solar receiver, the use of the sun inadequate.With fixed solar receiver compared to tracking solar receiver greatly improve the utilization of sunlight. Accordingly, the paper designs a 32-bit ARM based embedded chip, dual-axis automatic sun-tracking system, which can achieve automatically tracking the sun with high precision in a variety of conditions. II. SYSTEM DESIGN PRINCIPLE The sun's rays can be decomposed into two components, one perpendicular to the daylighting panel surface, and the other parallel to the surface, only the former radiation can be received by the daylighting panel. Thus, the angle between the sun’s rays and the normal of panel what is incident angle θ should be as small as possible. Incidence angle θ changes with the diurnal variation and seasonal variation. Therefore, the fixed-installed solar collectors can not fully absorb the solar radiation energy. If at any time by automatically tracking solar collectors can adjust daylighting panel position according to the sun's trajectory to reduce the incidence angle θ, it will be able to absorb more solar radiation energy than the fixed daylighting panels in the same irradiation conditions. The daylighting panel of dual-axis sun tracking system rotates around the two mutually perpendicular shafts, azimuth shaft and elevation shaft. It will track the sun's azimuth angle ω and elevation angle γ, so that daylighting panel can achieved incident angle θ of 0. Automatic sun-tracking system has two tracking mode: date-time calculate mode and camera mode. First of all, the date-time calculate mode is that the system calculate the theoretical value of the solar elevation angle and azimuth on a certain day at a certain hour under the laws of astronomy in the formula, and then run the control program to adjust the angle of daylighting panel to track the sun. Camera mode is that the system use a image sensor shooting the projection of sun through the convex lens on the panel, the system then calculates the deviation value between the center of projection and the center of panel, and then run the program to adjust the elevation angle and azimuth of daylighting panels to track the sun. The date-time calculate mode works regardless of weather or stray light interference, with high reliability, but the process in the calculation of the sun angle will produce errors, thus affect the tracking accuracy. Contrarily camera mode has high sensitivity, but is easily interfered with the external environment, the system reliability is lower. So you can see two methods are highly complementary. Combination of two methods can avoid outside interference by the greatest degree, but also modify errors that produced by theoretical calculation to improve the reliability of automatic tracking device and tracking accuracy. At the running time, the system collects GPS and image data once per minute. According to GPS information, it access to the local time 、 latitude and longitude, and then calculate the sun's azimuth angle ω and elevation angle γ of the next minute and Δω, Δγ of the difference between the current position. For image data, using the appropriate algorithm find the center of the sun projection. The sun projection as shown in Fig.1:
