電容特性沖擊能量收集效率

　　對于能量收集，電容器的選擇需要仔細考慮的特性超過簡單的電容值。在這些特性中，泄漏電流仍然是一個主要問題。今天，然而，設計師可以選擇從低漏電電解電容器高性能的超級電容器生產商包括AVX、Kemet、麥斯威爾、村田、NESSCAP、精工、臺喲宇扥、聯(lián)合化工，等等。

　　電容器經常出現(xiàn)在許多設計情況下的事后考慮，添加到電路清理信號和電源。在信號采集，電容器發(fā)揮了核心作用，在過濾帶源和采樣和保持階段的模擬/數(shù)字轉換器。然而，在能量收集應用中，電容器提供了一個重要組成部分，從低能量的環(huán)境源積累電荷和放電存儲電荷迅速和有效地加載到。在這些應用中，電容特性和元件選擇上升作為設計的重要因素。

　　In their traditional roles in circuit design， capacitors are considered as constant capacitance components for filtering， decoupling， and any of the other familiar uses for these devices. For those purposes， differences between the characteristics of an ideal capacitor and those of a real capacitor typically do not greatly impact their ability to fill their role adequately. For energy-harvesting applications， however， the departure from an ideal capacitor significantly impacts the efficiency of the design as a whole.

　　Among common effects （Figure 1）， equivalent-series resistance （ESR） and leakage current dominate an array of non-ideal characteristics that can degrade efficiency. High ESR causes a capacitor to dissipate power， particularly when subject to high AC currents. As such， the use of low-ESR capacitors results in overall higher efficiency in an energy-harvesting subsystem. Leakage current exerts a more profound effect in designs using very-low-energy ambient sources — and rises as a significant limitation in the ability to apply more familiar types of capacitors in energy-harvesting designs.