Energy storage in DC microgrid system using non-isolated bidirectional soft-switching DC/DC converter

摘要

The output of solar PV and battery is in the form of DC. Feeding of load from these sources requires conversion from dc to ac or dc to dc. DC microgrids popular for this feature in distributed generation on distribution systems. Energy storage in microgrid ensures electrical saving during no load or off load microgrid. To ensure power flow between DC microgrid and energy storage devices bidirectional dc-dc converter is required. The minimization of losses in dc-dc converter is a big task to improve efficiency. This paper proposes a non-isolated bi-directional DC/DC converter for interfacing DC voltage with energy storage in DC microgrid. The proposed converter is combination of current-fed half bridge boost converter and LCL resonant circuit for soft switching. Boost operation gained by 8 times with the help of front end boost converter, LCL resonant tank and doubler. For buck operation, high side voltage is divided by half with capacitor divider and front-end converter further clamp the voltage. In this paper, the detailed analysis and design is proposed for bidirectional dc-dc converter is done. Soft switching is also implemented by ZVS turn ON of switches and ZCS turn ON/OFF to diode. The performance analysis of proposed converter is done bidirectional power flow with soft switching in MATLAB/Simulink environment.