Design of Main Circuit Parameters for a Lightweight and Low-Cost New-Type VSC

This paper studies a novel Multilevel DC-Link Converter (MDC), featuring significant advantages in lightweight design and cost reduction. The MDC topology consists of three single-phase converters (SPCs), each comprising a multilevel DC link and a commutating H-bridge. These converters are connected in series on the DC side and interfaced with the three-phase AC grid via three single-phase transformers on the AC side. The document analyzes the topological structure and operational principles of the MDC, addressing the coupling issues between AC and DC voltage components. A decoupling design based on third-harmonic injection modulation is used to mitigate these interactions. Leveraging this foundation, parameter design methods for main circuit key components—including the converter transformers, DC links, and H-bridge modules—are systematically developed. The feasibility of the parameter design approach is validated through electromagnetic transient simulations, demonstrating the effectiveness of the proposed methodology in practical applications.