Power electronic for electrolysers

• Main Author: Chang, Effy Kit Yee
• Other Authors: Josep Pou
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Power electronics; Electrolysers
• Online Access: https://hdl.handle.net/10356/181676
• Institution: Nanyang Technological University

Hydrogen is a viable sustainable energy source, crucial for reducing carbon emissions and supporting the transition to a low-carbon economy. As countries strive to meet climate targets, hydrogen production through electrolysis has gained significant attention. This study explores hydrogen production via electrolysis, focusing on the role of power converter topologies in improving the efficiency of grid-connected and off-grid electrolysers. Starting with a comprehensive overview of hydrogen production, the research examines the key distinctions among various electrolysis processes. Key electrical parameters and AC-DC converter requirements are discussed to understand their influence on electrolyser performance. Subsequent chapters delve into uncontrolled and controlled power converter topologies. The use of a diode rectifier provides an uncontrolled voltage and current that is heavily reliant on the electrolyser parameters. Thyristor-based rectifiers are reviewed as a way for output voltage and current to be controlled. However, the downside to the thyristor-based rectifier is the much higher ripple factors compared to their diode counterpart. To bridge these topologies, the diode-chopper circuit is introduced, combining low ripple factors with controllability via DC-DC converters. The research also addresses renewable off-grid connections, particularly wind and photovoltaic systems, and their integration with electrolysers. In addition, the study proposes multi-stacked electrolyser configurations in series and parallel setups for high-power applications, assessing electrothermal balance to optimize performance in solid oxide electrolysis. This paper highlights that electrolyser efficiency can be increased through different converter topologies and configurations, setting the stage for future work aimed at enhancing large-scale hydrogen production capabilities.