利用於太陽能之高效率全積體化切換式電容升壓轉換器

Abstract

在科技日新月異的發展，穿戴式裝置產品越來越普及，並且環境污染問題越來越被重視，綠色能源的發展是必要的。其中，低汙染且永恆利用的太陽能，取代了電池需要被替換的優點，為主要替代電池的能源。應用方面有無線感測器、物聯網以及生醫電子元件。為了使太陽能技術能夠達到最高使用效率，內部的控制電路大量數位化電路，來達成低電壓低功耗的條件，並且讓電晶體操作在次臨界導通。也因為如此，目前的趨勢為高效率且低電壓的電源管理系統，由太陽能裝置產生的不穩定電壓的太陽能裝置轉換成穩定的系統電壓，在電路停止運作時也能保持低能量消耗，進而延長電池壽命。 本論文實現一個應用於太陽能下之全積體化並保持效率大於60%的轉換器，輸入電壓範圍在0.45 V到0.7 V之間。論文提出一個可在大範圍輸入電壓下操作的三模式切換是電容DC-DC轉換器，包含可調式電阻、頻率以及組態的穩壓功能。 其中，當輸出電壓穩定在1.2 V時，電路最高轉換效率達89%。在太陽能裝置輸出0.45伏~0.7伏的電壓的限制，控制電路及主電路大多在次臨界導通區域下操作，升壓到1.2伏的穩定電壓。 主電路以及控制電路大多操作在次臨界導通區域，使用數位方式來降低電壓之可調變電阻及頻率，並且在提出三模式的系統中操作。參模式升壓轉換器涵蓋從60奈安培到160奈安培之負載範圍，且峰值效率在100奈安培。

Science and technology are advancing with each passing day. The wearable products are more and more popular, and environmental problems are more and more important. So it’s required to green-life. One of the green resources is the solar energy. Unlike the battery, the solar energy is a renewable energy and causes less environmental problem. The solar energy is widely used in the applications of wireless sensors, biomedical electronics, and the internet of things (IoT). If all of the controller circuits are digitally designed and operated in sub-threshold region to reduce the power loss, the power converter supplied by solar cell can obtain a higher efficiency. Because of that, power management with high efficiency and low voltage operation is a popular research topic. The stable voltage is converted from variable solar energy source. The system has higher efficiency if it can be switched between the standby and active mode to extend the battery life. This paper presents a fully integrated energy harvester that is maintain > 60% efficiency when input power from 0.45 V to 0.7 V. A tri-mode switched capacitor DC-DC converter is proposed, because of the DC-DC converter including the adjustable resistance, frequency controller and tri-mode circuits to work with a wide input range. System maximum conversion efficiency is 89%, and the output voltage can be regulated at 1.2 V, when the solar cell voltage is varied from 0.45 V to 0.7 V. Both the controller and the main circuit are operating in the near/sub-threshold region. By combining both digital frequency and resistance modulation techniques to the proposed tri-mode topology, the converter can achieve high power efficiency over a wide output current range of 60 uA to 160 uA. Peak efficiency occurs at 100 uA.