A Wireless Power Transmission System Based on Solar Power and Switched Beam for Charging Multiple Wireless Sensor Nodes

本論文提出一個2.45 GHz頻段的遠距離無線充電架構，包含兩個主要部分：功率傳送源與可汲取能量的無線感測節點。大體而言，此一架構為基於儲存太陽能源且用於無線感測網路的射頻無線充電創新裝置，就作者所知，文獻中尚無接近的設計發表。本論文根據美國聯邦通訊委員會之射頻電波使用規定，提出系統設計、實作和提出硬體選擇的建議。本論文構想的系統使用太陽能板為能源，收集太陽能轉換成為射頻能量，運用陣列天線切換主波束方向，將射頻能量傳送到所安排的感測節點。至於感測節點的接收端，接收功率源的能量後，採用作者提出的充電邏輯，提供直流電給感測器。此一系統之射頻與直流電的轉換效率達20~30%，尚稱有效。In the thesis, we propose a new far-field wireless power transmission system at 2.45 GHz ISM band, including a power source and energy harvesting circuits for wireless sensor nodes. To the best of our knowledge, no publish work has discussed the design that contains both RF power transmitter and receivers for WSNs in a solar based wireless power transmission system. By observing the regulations of Federal Communication Committee (FCC), we have implemented the system and suggested several parameter settings and selections of hardware for design. Moreover, in most RF harvesting scenarios, RF sources are not steady but solar power density is relatively high, so we make a combination of solar power and RF harvesting in our proposed system. Solar power is collected and then transformed into controllable RF power for transmission in four desired directions. As for wireless sensor nodes, the RF harvesting circuit is designed and implemented with about 20~30% RF-DC conversion efficiency, and a new charging logic is proposed as well. In summary, a whole-system scope of WPT technique is illustrated and can be a good example of the rechargeable WSNs design in the future