A Topology of Current-Fed DC Electric Spring

Renewable energy generation becomes the trend of power industry. However, its consumption is hitting a bottleneck. Electric spring (ES) is one of the effective means to solve the issue. A current-fed direct current electric spring (CF-DCES) topology is proposed in this paper, which consists of a current-fed three port converter (TPC) and a bidirectional Buck-Boost converter (BBC). The modal analysis of the CF-DCES is carried out by means of the current-type three-port equivalent circuit, and the corresponding small signal model is solved. The input current and critical load voltage are taken as control variables, and the duty ratio on the input side and that on the critical load side are taken as output variables. The output variables are decoupled according to the small signal model. Non-critical load is set to absorb input power fluctuation. A group of batteries is set at BBC port to ensure the power requirements of the critical load. A type of battery energy management system is also proposed. Finally, the proposed CF-DCES is validated by both simulation and experimental results.