NEXT-GENERATION DC MICROGRID CONTROL USING MULTILEVEL POWER CONVERTERS

Abstract

Direct-current (DC) microgrids are increasingly attractive for integrating photovoltaics, battery energy storage, and high-efficiency electronic loads. However, maintaining bus voltage quality, accurate current sharing, and stability in the presence of fast electronic loads is challenging— especially as power levels and dynamics scale. This paper presents a next-generation DC microgrid control architecture built around multi-level power converters that natively support high voltage, low switching stress, and fine voltage resolution. The proposed scheme combines finite-set model predictive control (FS-MPC) at the converter level with droop-based primary control, distributed secondary control for voltage restoration and current-sharing accuracy, and a tertiary energymanagement layer. A 380-V DC microgrid prototype with a 5-kW photovoltaic (PV) emulator, 5- kW/10-kWh battery, and programmable constant-power loads validates the approach using a neutralpoint-clamped (NPC) three-level converter at the bus interface. Experiments demonstrate ±0.5% busvoltage regulation under 50% step load changes, ≤2% current-sharing error among parallel sources without communication during transients, and robust damping against constant-power loads that would destabilize conventional droop controllers. The results indicate that multi-level hardware paired with predictive and hierarchical control unlocks higher stability margins, lower switching losses, and improved power-quality in modern DC microgrids.