超低電壓能量采集器采用熱電發生器實現無電池無線傳感器

　　超低功耗無線傳感器節點的測量和控制，結合新的能量收集技術，使得能夠產生完全由本地環境能量而不是電池供電的自治系統成為可能。從環境或“自由”能量供電無線傳感器節點是有吸引力的，因為它可以補充或消除對電池或電線的需要。當電池更換或維修不方便、昂貴或危險時，這是一個明顯的好處。

　　電線的完全缺乏也使得大規模監控和控制系統的擴展變得容易。能量收集無線傳感器系統簡化了在樓宇自動化、無線/自動計量和預測維護等眾多領域的安裝和維護，以及許多其他工業、軍事、汽車和消費應用。

　　能量收集的好處是顯而易見的，但一個有效的能量收集系統需要一個聰明的電源管理方案，將自由能極小的水平成了無線傳感器系統的可用。

　　It‘s all about the duty cycle

　　Many wireless sensor systems consume very low average power， making them prime candidates to be powered by energy harvesting techniques. Many sensor nodes are used to monitor physical quantities that change slowly. Measurements can therefore be taken and transmitted infrequently， resulting in a low duty cycle of operation and a correspondingly low average power requirement.

　　For example， if a sensor system requires 3.3 V at 30 mA （100 mW） while awake， but is only active for 10 ms out of every second， then the average power required is only 1mW， assuming the sensor system current is reduced to microamps during the inactive time between transmit bursts. If the same wireless sensor only samples and transmits once a minute instead of once a second， the average power plummets under 20 μW. This difference is significant because most forms of energy harvesting offer very little steady-state power–usually no more than a few milliwatts， and in some cases only microwatts. The less average power required by an application， the more likely it can be powered by harvested energy.