A Design Approach for SoC Integration With Voltage Restoration Capability for Redundancy-Based DC Microgrids

The article presents a secondary voltage control design for an Energy Management System (EMS) in a redundancy-based dc microgrid (MG) through a fuzzy-based approach, suitable for vehicles, aircraft, and medical centers with sensitive loads. Two battery energy storage system (BESS) units serve as common inputs for the redundancy-based dc MG, comprising a cascaded bidirectional Cuk converter (CBC) connected to an auxiliary cascaded bidirectional Boost converter (CBB). The CBC acts as the primary electronic solution, while the CBB enhances reliability by maintaining operation in case of a CBC failure. Furthermore, a Fuel Cell (FC) is linked to the main dc-link of the CBC by a Boost converter. The key contribution lies in the fuzzy-based voltage restoration for the EMS, integrating SoC equalization via S-shaped functions, even during BESS, FC, or CBC maintenance. As the EMS operates as a current source-based system, voltage variations on the dc-link are expected. However, after fuzzy-based restoration, the voltage deviation remains below 2% and the operational efficiency exceeds 90%. Stability analysis is conducted using Lyapunov’s indirect method, and the proposed approach is supported by experimental results obtained through SpeedGoat and dSPACE platform interactions.