低功率獵能器與充電電路設計

Abstract

本論文目的為設計新式獵能電路可將微發電機所輸出的微小電壓能源轉換成實際可用電源。以微發電機設計來說，當微發電機所設計的尺寸越微小越符合可攜式產品，其所發出的能量即越來越微小，輸出電壓也越來越低，當低於二極體臨界電壓附近甚至以下時，後端電路即無轉換效率可言，故如何設計低輸入且高效率的獵能電路即是本論文的目的所在。論文當中新式電路設計有三，一為可允許低輸入電壓的克服臨界電壓型的獵能電路，其設計特性為克服臨界電壓在電晶體型二極體中的影響以達成超低輸入電壓，並提高其轉換效率，用以超低輸出電壓的微發電機，二為無電池式高效率的獵能電路設計，其特性為不需任何額外電源且升壓過程中有著一特性，即為所有電容吸收能量而所有電容也共同輸出能量，故理論上可達成最高效率的能源轉換，且具備急速升壓特性在單一週期即可升壓至目標，在模擬與驗證方面，將以交流電壓訊號虛擬成微發電機之動作，並將設計完成之電路以此虛擬之交流電壓加以模擬並驗證所設計的電路功能。而本文針將對微發電機後端的獵能電路設計與模擬，其整體設計流程從原理了解、電路設計、H-SPICE軟體模擬修正、晶片設計、實體佈局與下線及晶片量測結果，最後，還設計一新式充電電路以達成快速充電與精準偵測電池滿充時的狀態，用來儲存電力。

This study is to design an energy harvest circuit to collect energy from micro-generator for driving rear-end electronic device. Since the size and output voltage of micro-generator is small and low, the efficiency of the energy harvest circuit is almost zero where the voltage of micro-generator is lower than threshold voltage of switching MOSFETs. There circuit designs are proposed in this study to remedy the aforementioned problem. One is designed to overcome the threshold voltage of MOSFET diodes, and it can be used for low output voltage of micro-generator. Another one is a high efficiency energy harvest circuit without external power source. The energy harvest circuit without external power source pumps the voltage of micro-generator in a short time. In order to get the high efficiency, this proposed design only uses the storage capacitors to storage the energy and it outputs by all storage capacitor. Finally, a new battery charger is designed for detecting exactly current of battery and decreasing the charging time. Consequently, the external energy is successfully collected to the battery.