Bidirectional Power Flow Control of a Multi Input Converter for Energy Storage System

The objective of this paper is to propose a multi-input DC-DC converter with bidirectional power flow control capability. Compared to the traditional power converter, the multi-input converter (MIC) can save on the number of components and the circuit cost. Under normal conditions, the MIC is able to transfer energy from different input sources to the load. However, if the battery module is adopted, both the charging or discharging features should be considered. Therefore, the bidirectional power flow control of the MIC is necessary. On the other hand, because of the inconsistency characteristics of batteries, unbalanced circuit operation might occur whereby the circuit and the battery might be damaged. Therefore, dynamic current regulation strategies are developed for the MIC. Consequently, the proposed MIC circuit is able to achieve the bidirectional power flow control capability as well as control the input currents independently. Detailed circuit analysis and comprehensive mathematical derivation and of the proposed MIC will be presented in this paper. Finally, both simulation and experimental results obtained from a 500 W prototype circuit verify the performance and feasibility of the proposed bidirectional multi-input converter.