應用於壓電能量擷取系統之飛電容同步切換能量擷取電路與壓電能量無線傳感器系統

Abstract

物聯網（IoT）透過連接我們周遭的每個東西改變我們的生活與工作方式，這些連接使我們能夠透過傳感器收集和分析數據，從而實現決策與自動化流程。所以簡化感測器供電以及回收數據成為降低建置與維護成本的關鍵，微機電壓電擷取技術有高能量密度的特性，因此替換笨重的電池為感測器節點供電；此外感測器節點的數據無線傳輸也能取代複雜的實體佈線。 本論文以壓電能量擷取介面電路的分析、晶片設計實作與系統設計實作為主。在傳統上，壓電能量擷取介面電路往往使用翻轉因子較差的全橋整流器；然而因二極體之順向跨壓使得全橋整流器之輸出功率較差，因此便有了同步切換能量擷取介面電路的提出，使用電感或電容作為偏壓翻轉元件。若使用電感作為偏壓翻轉元件，則有電磁干擾且體積過大的缺點；若使用電容作為偏壓翻轉元件，則有開關切換次數多的缺點。因此本論文提出改善架構 – 共用開關式之飛電容整流能量擷取介面電路(Switching Sharing Flying Capacitor Rectifier Interface Circuit)，在使用電容的條件下解決開關切換次數的缺點。在系統整合上實作了一從壓電能量擷取器開始，透過微控制器整合多感測器，並使用無線傳輸資料至手機之伺服器之無線傳感器系統。 本論文以台積電180 nm高壓BCD製程完成電路實作，依佈局後模擬所顯示，電壓翻轉因子達到63.3 %，且與電路中的主動整流器相比具有641 %的輸出增益。無線傳感器全系統以Nordic nrf51822做為核心，能夠在能量平衡的條件下每4分鐘傳輸一次資料。

The Internet of Things (IoT) is revolutionizing the way we live and work by connecting our daily life to the internet. This connectivity allows us to collect and analyze data through sensors, enabling informed decision-making and the implementation of automated processes. Therefore, adopting a low maintenance cost power supply method and implementing wireless data collection becomes crucial for reducing setup and maintenance costs. MEMS (Micro-Electro-Mechanical Systems) energy harvesting technology has high energy density characteristics, which makes it a suitable replacement for bulky batteries to power sensor nodes. The convenience of wireless data transmission from sensor nodes also surpasses the complexity of physical wiring. This work focuses on the analysis of a piezoelectric energy harvesting interface circuit, its chip implementation, and system integration. Traditionally, the piezoelectric energy harvesting interface circuit often utilizes a full-bridge rectifier, but it has a poor flipping factor due to the diode's forward voltage, which reduces the output power. To address this issue, a synchronous switching energy harvesting interface circuit is proposed, employing either an inductor or a capacitor as a bias flipping medium. However, using an inductor as the bias flipping medium results in electromagnetic interference and a bulky size, while using a capacitor leads to the disadvantage of frequent switching. Therefore, this work introduces an improved architecture called the "Switching Sharing Flying Capacitor Rectifier Interface Circuit" to overcome the frequent switching drawback when using capacitors while benefiting from energy concentration. For system integration, a wireless sensor system was implemented, starting from a piezoelectric energy harvester. It integrates multiple sensors through a microcontroller and wirelessly transmits data to a server connected to a mobile phone. In this work, the circuit is implemented in TSMC's 180 nm high-voltage BCD process, and the post-layout simulation shows a voltage flipping factor of 63.3 % and an output gain of 641 % compared to the active rectifier in the circuit. The wireless sensor system is based on the Nordic nrf51822 microcontroller, which is capable of transmitting data every 4 minutes under energy balance condition.