A Four-quadrant Buck-boost Partial Power DC/DC Converter for Battery Energy Storage System

As the power level of battery energy storage systems (BESS) increases, the issues of low efficiency and low power density resulting from the high power demands of traditional full power converters (FPC) become more apparent. To solve them, a four-quadrant buck-boost partial power converter (PPC) is proposed, in which the internal DC/DC of the converter flows only a small portion of the total power, while the remaining power is transferred directly between the battery and the DC bus through the feedforward path. This paper examines the performance evaluation methods of the PPC from various perspectives. It describes the advantages and limitations of the four-quadrant buck-boost PPC, and presents a design for the topology and control strategy based on a CLLC resonant circuit. Through simulation, the automatic operation of the converter in all four modes is achieved. The proposed is compared to the FPC under the same operating conditions, and the paper highlights the advantages of the four-quadrant buck-boost PPC in terms of efficiency, power density, active and nonactive power, and component stress.