Parallel Interleaved Current Source Rectifiers for High-Power Hydrogen Electrolyzers and Optimal DC Inductance Design

Due to their single-stage step-down nature, current source rectifiers (CSR) constitute attractive options for supplying high-power electrolyzers. To increase system power rating, parallel configurations can be adopted with interleaved Pulse Width Modulation (PWM) techniques that improve power quality and reduce the size of filtering elements. Optimal design of the output dc inductance is crucial to achieve cost-effective and competitive solutions. However, common design methods for one single CSR do not achieve optimal designs. There are hardly any specific design methods for interleaved CSRs either. This paper analyzes the operation of parallel interleaved CSRs supplying high-power electrolyzers and develops a methodology to optimally size the output dc inductances. In addition, a common mode equivalent circuit is developed to analyze the circulating currents caused by the interleaved operation and calculate the ripple in the inductances. When applied to a 3 MW electrolyzer, the results show that inductance size reductions of up to 69% can be obtained with the proposed methodology.