A Bipolar DC-DC Converter with Wide Voltage-Gain Range for Energy Storage Integration in Ship Power Systems

Abstract

Ship Power System (SPS) with medium voltage direct current (MVDC) is attracting widespread interest due to higher reliability and reduced fuel consumption. Energy storage system (ESS) is recognized as being the critical part of the MVDC distribution power system, enabling peak shaving, zero emission operation, and optimal scheduling of generators. In this paper, a bipolar dc-dc converter with wide voltage gain range is proposed for interfacing ESS with DC-bus in SPS. To protect the ESS against rapid discharging due to any short-circuit fault on the DC-bus, a high-frequency transformer is adopted in the proposed topology. Moreover, diode-capacitor circuits are employed in the secondary side to provide a wide voltage gain. The converter takes advantage of active clamp configuration, in terms of limiting the voltage stress of switches and providing soft-switching performance. The extension of the proposed concept for application with multiple loads, detailed analysis of the steady-state operation of the converter, and battery discharge limiting capability are given in this paper. Finally, a simulation in MATLAB/Simulink platform is carried out to validate the correctness of the theoretical analysis.