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標題: | 應用傳輸偶極天線陣列之調變技術以實現在旋轉錯位及位移錯位下穩定的無線供電網路系統 Modulation Techniques for Transmitting Dipole Array to Realize Stable Power Reception Under Rotational and Location Misalignment |
作者: | Yu-Heng Cai 蔡宇恆 |
指導教授: | 盧信嘉(Hsin-Chia Lu) |
關鍵字: | 無線供電網路,無線功率傳輸,傳輸偶極天線陣列,分時傳輸調變,功率偵測電路,射頻能量採集系統, wireless power grid,wireless power transmission,transmitting dipole array,time switching modulation,power detector,RF energy harversting system, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 無線供電網路可應用於免電池物聯網裝置與無線射頻辨識系統,其優點為減少內部連接線材的使用及電池的更換,然而使用單一發射器架構的傳輸效率會受收發端之旋轉錯位與位移錯位影響。為了解決此困境,本論文分別介紹在二維架構及三維架構之非對稱傳輸偶極天線陣列應用相位調變、頻率調變及分時傳輸調變以實現接收端之平均功率不受旋轉角度影響,然而此架構的缺點為當接收器偏離中心點時,接收端之平均功率受距離因素影響導致接收功率穩定性變差。
本論文再提出對稱傳輸偶極天線陣列以減少旋轉錯位與位移錯位所導致的功率變化。根據弗里斯傳輸方程式估計接收功率,接收端之平均功率在穩定區內皆不受旋轉錯位與位移錯位影響,即接收器在此範圍內皆能獲得足夠穩定的能量。當多發射器以相同頻率同時激發時,接收端之平均功率受駐波干擾而導致能量分佈不均勻,因此本論文應用分時傳輸調變以實現穩定的能量分佈,即利用切換開關控制發射器之導通時間,在一段時間內只允許一個發射器導通。由接收天線在不同旋轉角度與位置之標準差的比較,二維架構之對稱傳輸偶極天線陣列比非對稱傳輸偶極天線陣列的接收功率標準差改善高達81.3 %,而三維架構之對稱傳輸偶極天線陣列比非對稱傳輸偶極天線陣列的接收功率標準差改善高達66 %。 量測方面可分為兩個部分,第一部分以單極天線與整流器所形成之功率偵測電路作為射頻能量採集系統將空間中的射頻能量轉換為直流電壓以便於量測。第二部分以Arduino應用開發板內建之10位元的類比數位轉換器,陀螺儀、加速度計、磁力計所形成之九軸姿態感測模組與Wi-Fi無線網路模組所構成之遠端量測系統可同時量測電壓及接收天線的旋轉角度,數據資料會透過Wi-Fi無線網路模組傳送至手持式裝置上以實現即時監控之目的。為了考量多重路徑干擾,本論文之無線功率傳輸實驗於室內環境進行量測,以驗證分時傳輸調變於中心點附近皆能獲得足夠穩定的接收功率,其理論分析、全波模擬與量測結果大致吻合。 Several practical applications such as battery-less internet of things (IoT) devices and radio frequency identification (RFID) systems requires wireless power transmission. The advantages including reduction of wire harness and no requirement of battery replacement. Nevertheless, transfer efficiency is influenced by rotational and location misalignment in single transmitter architecture. To tackle this problem, modulation schemes such as phase modulation, frequency modulation and time switching modulation are proposed for asymmetric transmitting dipole array to realize stable power reception under rotational misalignment. The drawback of this architecture is when the receiver is moved away from the center point, the time-averaged received power becomes unstable due to different distances. Symmetric transmitting dipole array is thus proposed in this thesis to mitigate power variations due to rotational and location misalignment. Friis transmission equation is used to estimate received power and to ensure sufficiently stable power in steady regions. If multiple transmitters are excited at the same frequency simultaneously, standing waves and interference occur in the transmission path. Therefore, time switching modulation is introduced to realize uniform power distribution. Compared with the standard derivation of asymmetric transmitting dipole array at different angles and locations, the symmetric one can yield an improvement up to 81.3 % at 2-D case and 66 % at 3-D case, respectively. The measurement set-up is divided into two parts. First, monopole antenna and rectifier are used as a RF energy harvesting system to convert RF energy to DC voltage for convenient measurement. Second, the analog voltage is converted into digital number by using 10-bit A/D converter in Arduino board. A 9-axis sensor module including gyroscope, accelerometer and magnetometer is used to measure rotation angle of the receiving module. Wi-Fi connection module is used to deliver measured voltage and rotation angle to mobile phone for real-time monitoring. The experiment is conducted in indoor environments to take multipath effect into account. Time switching modulation is exploited to realize stable power around center region. The measurement results have good correspondence with the full-wave simulation and equation analysis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/15270 |
DOI: | 10.6342/NTU202000439 |
全文授權: | 未授權 |
顯示於系所單位: | 電信工程學研究所 |
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ntu-109-1.pdf 目前未授權公開取用 | 10.27 MB | Adobe PDF |
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