Ultracapacitor frequency analysis and its equivalent circuit modeling

Energy storage system is becoming more and more important in power electronics device. The Ultracapacitor or so-called electrochemical capacitor is one of the most popular choices for the energy storage system because of its distinct characters. In the application UCAP´s transient behavior need to be studied for design purpose. Usually these transient characters are not shown in the product data sheet. In this paper UCAP frequency analysis is performed, and based on the test data the equivalent model of the UCAP is built. The fitting result shows that using multi-level ladder circuit can perfectly fit the UCAP transient characters.