Design three-level converter as super capacitor interface for EV hybrid energy storage system

The super capacitor (SC) battery hybrid energy storage system (HESS) can be widely used as the energy bank with lots of advantages. Optimized topologies and high-efficiency converters are necessary as the power interface of SC bank for different applications. In this paper, the converter prototype with three-level (TL) topology is applied as SC power interface, which is designed to link low-voltage DC bus with bidirectional high current output ability for electric vehicles (EV) application. The comparative analysis of components size and converter loss is made based on the experiments among different converter topologies, which shows the effectiveness of three-level converter in our application. The control principle and action modes of three-level converter are introduced. Two aspects of converter control design, the response of output current control loop and the voltage balance between the two SC banks in three-level topology, will be considered in the following step.