適用於壓電能量擷取系統的新穎同步電壓反轉與電荷擷取整流器

隨著物聯網(Internet of Things)的崛起，我們生活周遭出現了愈來愈多感測器，這些感測器會對環境進行數據蒐集，若與設備相互連結便能形成一個智慧網絡。近年來全球運作中的物聯網裝置數量來到了70億個裝置數量，且每年以驚人的速度成長。若要用電池為這些感測器進行供電，則大量的廢棄電池將會對環境造成嚴重的影響。若環境中有馬達或引擎等振動源，我們就可以利用壓電能量擷取系統(Piezoelectric energy harvesting system)來捕捉環境中的振動能，並將能量儲存到儲能電容上，為各式感測器供電。　　壓電能量擷取系統包含壓電元件、介面電路與儲能電容。其中介面電路又包含整流器、交流-直流轉換器(AC-DC converter)、直流-直流轉換器(DC-DC converter)。壓電能量擷取的順序如下，壓電元件能夠將振動機械能透過壓電效應轉為交流電訊號，接著透過整流器或交流-直流轉換器將交流電訊號轉為直流電訊號，最後透過一級直流-直流轉換器將能量輸出到儲能電容上，以提供穩定的直流電給感測器。其中常見的壓電能量擷取之交流-直流轉換器包含了標準介面電路(Standard interface circuit)、電感式同步切換能量擷取電路(Synchronized Switching Harvesting on Inductor, SSHI)、同步電荷擷取電路(Synchronous Electric Charge Extraction, SECE)等介面電路，而直流-直流轉換器包含了降壓轉換器(Buck converter)、低壓差穩壓器(Low-dropout regulator, LDO regulator)與開關電容電路(switched-capacitor circuit)等電路。本論文將專注於交流-直流轉換器的設計與晶片實現。　　本實驗團隊與法國INSA Lyon團隊在2017年共同提出了一個壓電能量擷取介面電路(Piezoelectric energy harvesting interface circuit)——同步電壓反轉與電荷擷取(Synchronous Inversion and Charge Extraction, SICE)介面電路，該電路相較於其他壓電能量擷取介面電路，具有突破性的輸出功率提升、負載隔離效應以及更廣泛的應用場景。本論文作者更進一步提出了新穎的SICE介面電路架構(Circuit topology)，並實現了第一個SICE介面電路晶片。本論文所提出的電路架構僅用了四個MOSFET開關(Switch)與一個電感，便能實現具有負載隔離(Load independence)、耐高壓以及高輸出功率增益(Output power gain)的晶片。本晶片採用台積電0.25μm高壓CMOS製程，經由電路模擬、離散電路實驗與晶片實現等研究方法來實現所提出的電路。根據佈局後(Post-simulation)的模擬結果，在壓電元件等效電路中的電流源振幅為22.5μA、振動頻率為120Hz、等效電容為15nF的條件下，透過本SICE電路可以從壓電元件上汲取更多功率。本電路的輸出功率可達42.4μW，FOM值達78.2%，是標準介面電路的5.86倍，即具有586%的輸出增益。晶片量測方面，由於晶片外部之離散元件有著不理想之寄生效應，使反轉係數下降，經量測後測得晶片輸出功率為27.3μW，FOM值達75.6%。　　最後本論文將針對本實驗團隊成員所設計的同步電荷擷取 (Synchronous Electric Charge Extraction, SECE)整流器晶片進行量測，以驗證其晶片功能之完整性，並對部分電路進行優化。

關鍵字

物聯網；感測器；壓電能量擷取；同步電壓反轉與電荷擷取整流器；同步電荷擷取整流器

並列摘要

With the rise of the Internet of Things (IoT), there are more and more sensors applied around us. These sensors collect data from the environment, and further form a smart network if connected to other devices. In recently years, the total number of active device connections worldwide is reaching 7 billion. If the sensors are powered by batteries, the limited lifetime can cause numerous abandoned batteries, which may seriously polluting the environment. To solve these issues, installing piezoelectric transducers around vibration sources such as motors or engines can help us to harvest the environmental energy to the storage capacitor, which can further power the IoT wireless sensors. The piezoelectric energy harvesting system includes piezoelectric transducer, interface circuits and storage capacitor, where interface circuits are usually contain rectifier, AC-DC converter and DC-DC converter. Firstly, piezoelectric transducer converts the vibrational energy into AC electric signal through piezoelectric effect. Then convert the AC signal into a DC signal through the rectifier. Finally, the energy is output to the storage capacitor through a DC-DC converter in order to provide a stable DC source to the connected sensors. The common AC-DC converters for piezoelectric energy harvesting system include standard interface circuit, SSHI, SECE etc. On the other hand, the common DC-DC converter include buck converter, low-dropout regulator(LDO regulator), switched-capacitor circuit, and so on. This paper dedicates to circuit design and chip implementation of AC-DC converter. In 2017, our research team and French research team in INSA Lyon jointly proposed a piezoelectric energy harvesting interface circuit, Synchronous Inversion and Charge Extraction (SICE) circuit, which performs breakthrough output power gain, load independent characteristic and wider range of applications. The author of this paper further propose a novel SICE interface circuit architecture, and successfully implement the first SICE circuit chip. The proposed architecture achieve load independence, HV (High-voltage) process and high output power gain by only four MOSFET switches and one inductor. The chip is implemented by TSMC 0.25μm HV CMOS process, realized by research methods such as circuit simulation, discrete circuit experiment and chip design. According to post-simulation results, the output power of the chip is 42.4μW and the FOM value is 78.2% when operating with a piezoelectric transducer under a certain condition as follow: current source amplitude 22.5μA, operating frequency 120Hz and internal parasitic capacitance 15nF. By the proposed SICE architecture, the chip can draw more power from piezoelectric transducers. Compared to the standard interface circuit, the proposed novel SICE circuit provides 586% power gain. On the chip measurement side, the discrete components have undesirable parasitic effects, which can reduce the inversion factor. The output power of the implemented chip is 27.3μW, and the FOM value is 75.6%. Finally, measurement and function verification of a SECE (Synchronous Electric Charge Extraction) rectifier chip, which had been implemented by our research team member, will be done in this paper. Some sub-circuits optimization will be finished as well.

並列關鍵字

Internet of Things ； wireless sensor ； rectifier ； piezoelectric energy harvesting ； SICE ； SECE

參考文獻

[1] S. Li, L. Da Xu, and S. Zhao, "The internet of things: a survey," Information Systems Frontiers, vol. 17, no. 2, pp. 243-259, 2015.

Google Scholar

[2] Forbes. (2018). 2018 Roundup Of Internet Of Things Forecasts And Market Estimates. Available: https://www.forbes.com/sites/louiscolumbus/2018/12/13/2018-roundup-of-internet-of-things-forecasts-and-market-estimates/#305122af7d83

Google Scholar

[3] IoT-Analytics. (2018). State of the IoT 2018: Number of IoT devices now at 7B – Market accelerating. Available: https://iot-analytics.com/state-of-the-iot-update-q1-q2-2018-number-of-iot-devices-now-7b/

Google Scholar

[4] S. Roundy, P. K. Wright, and J. Rabaey, "A study of low level vibrations as a power source for wireless sensor nodes," Computer communications, vol. 26, no. 11, pp. 1131-1144, 2003.

Google Scholar

[5] S. Roundy and P. K. Wright, "A piezoelectric vibration based generator for wireless electronics," Smart Materials and structures, vol. 13, no. 5, p. 1131, 2004.

Google Scholar

國際替代計量

適用於壓電能量擷取系統的新穎同步電壓反轉與電荷擷取整流器

全文下載

主題瀏覽