Energy management method of supercapacitors storage system for UPS applications

For some kinds of motor drive systems, such as the variable-pitch wind power system, the back-up power needs to output very high power in a short time to meet the emergency. And the work temperature range and cycle life is required more strictly. Supercapacitors are very suitable to be the energy storage component due to its advantages of high power density, high charging speed and extremely high cycling capability. However, the energy density of supercapacitor is relatively low, so the energy management method of supercapacitors based UPS is very important to increase the energy usage efficiency. In this paper the finite state machines theory is applied as management method for supercapacitors based uninterruptable power supply (UPS). Design procedure is discussed in detail. Finally, the simulation and experimental results are provided to verify the design.