Double-layer-capacitors (DLCs) are capacitive elements, that are able to store a huge amount of energy. Due to the low specific voltage of one DLC-cell a number of cells have to be connected in series to achieve higher power output. In order to use the full capacitance of the DLC storage system, the cell-voltages have to be balanced and monitored. A suitable bypass-circuit has been designed and optimized. The integrated feedback ensures a safe operation of the storage system at any state of charge. Due to their internal time constant the DLCs have an outstanding capability to store and release energy within some hundred milliseconds to a few seconds. Therefore the DLC is rather a “power storage” than an energy storage device. For different applications several characteristics of the DLC have to be considered in different ways. The rating and the construction of DLC storage systems for two different applications are represented exemplarly. The importance of different design criteria with respect to the specific application is pointed out and the results are proven by measurements.
Optimization of double-layer-capacitor storage systems for different applications
ESSCAP '08, 3rd European Symposium on Supercapacitors and Applications, 6.-7.11.2008, Rom