1-MW Full-Bridge MMC for High-Current Low-Voltage (100V-400V) DC-Applications

Konferenz: PCIM Europe digital days 2020 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
07.07.2020 - 08.07.2020 in Deutschland

Tagungsband: PCIM Europe digital days 2020

Seiten: 8Sprache: EnglischTyp: PDF

Autoren:
Unruh, Roland; Schafmeister, Frank; Froehleke, Norbert; Boecker, Joachim (Power Electronics and Electrical Drives, Paderborn University, Germany)

Inhalt:
A full-bridge modular multilevel converter (MMC) is compared to a half-bridge-based MMC for high-current low-voltage DC-applications such as electrolysis, arc welding or datacenters with DC-power distribution. Usually, modular multilevel converters are used in high-voltage DC-applications (HVDC) in the multiple kV-range, but to meet the needs of a high-current demand at low output voltage levels, the modular converter concept requires adaptations. In the proposed concept, the MMC is used to step-down the three-phase medium-voltage of 10 kV. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage range of 142-220V and to provide galvanic isolation. The proposed MMC converter with full-bridge modules uses half the number of modules compared to a half-bridge-based MMC while reducing the voltage ripple by 78% and capacitor losses by 64% by rearranging the same components to ensure identical costs and volume. For additional reliability, a new robust algorithm for balancing conduction losses during the bypass phase is presented.