Three-level back-to-back converters with ESS directly connected to the lower DC-link

摘要

With the conventional circuit configuration of DC microgrids, two power conversion stages are required to transfer the energy from the Energy Storage System to loads or sources: DC/DC and DC/AC conversions. This paper proposes a new circuit configuration which puts the battery directly to the lower DC-link of 3-level back-to-back converters. The proposed circuit reduces the two-step power conversion stage to one-step. The working principle of the proposed circuit is analyzed, and the controllers for the circuit are designed. The validity of the control algorithm is verified by computer simulation.