被動式雙軸太陽追蹤器之追控系統開發

Tracking Control System of the Two Axes Passive Solar Tracker

張智凱(Jhih-Kai Jhang)

指導教授 ： 吳俊諆

國立中央大學/工學院/能源工程研究所/碩士(2008年)

摘要

本文針對應用於高聚光型太陽光電系統(high concentrated photovoltaic, HCPV)的雙軸追蹤機構開發一套被動式追控系統，HCPV的特色是需搭配高功率的三五族太陽電池，而三五族太陽電池僅能吸收直射的太陽日照，因此依據需求對追蹤器的追蹤精度需小於0.5°，避免入射角誤差過大導致太陽電池吸收直射日照量降低。
被動式追蹤的原理是藉由天文學中的地平座標系來定位太陽位置，依據追蹤器所在地區的緯度、經度以及時區計算出太陽仰角及方位角每日變化的軌跡外在驅動元件採用步進馬達，馬達選用需考慮能提供足夠機構轉矩及轉速方能跟上太陽軌跡的快速變化（特別在正午時）。
追控系統的程式以Labview軟體撰寫，藉由Labview的虛擬儀表功能讓電腦做為具有人機介面的控制器。當太陽的仰角及方位角每變化0.2°追控系統便會驅動步進馬達帶動追蹤器，量測誤差角度是使用精度為0.1°的視準管(collimating tube)，並利用數位相機記錄投射在視準管內的太陽光點影像，再判讀追蹤器的角度偏差。戶外測試數據顯示能達到追蹤精度小於0.5°，也驗證被動式追蹤方式應用於HCPV的可行性。

關鍵字

追日控制 ； 高聚光太陽能技術 ； 被動式雙軸追蹤器

並列摘要

The purpose of this research is to develop a passive sun-tracking control system for high concentrated photovoltaics (HCPV), which uses two axes tracking mechanisms. HCPV uses III-V solar cell which has higher efficiency and can only absorb the direct solar irradiation. In order to reducing the error of incident angle, which causing degradation of insolation absorption of the solar cell, the precision of tracker is set to be smaller than 0.5°.
The passive tracking adopted in this study is utilizing the horizontal coordinates of astronomy, which depends on the latitude, longitude and time zone of the tracker’s location to calculate the altitude and azimuth of the solar. The stepping motor, which drive the tracking mechanisms, is chosen to provide adequate rotating torque for mechanism and rpm for coping with rapid motion of the solar trajectories (particularly in the noon).
This control system is programming with Labview software. When the solar altitude and solar azimuth move at angle of 0.2°, the controller drives the stepping motor to actuate the tracker. A collimating tube with an accuracy of 0.1° is used to measure the error of tracking angle, and recorded the light spot in the collimating tube with a digital camera to analyzing the error distribution. At the outdoor test, experiment results show that the average angle error is less than 0.5° and which prove the feasibility of the passive sun-tracking system can be used in HCPV.

並列關鍵字

sun-tracking control system ； two axes passive solar tracker ； HCPV

參考文獻

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