High-Efficiency Seven-Level Converter for MVDC Electric Aircraft Propulsion: A Hybrid Si-IGBT and SiC-MOSFET Approach

The transition to electric propulsion systems in aviation is a key trend toward achieving higher efficiency, reduced fuel consumption, and lower maintenance costs, while significantly reducing the carbon footprint of aircraft. Medium-voltage DC (MVDC) distribution has emerged as an effective solution. This paper explores the application of the seven-level converter in aircraft electric propulsion systems. It provides a detailed analysis of its operating modes and modulation principles, and based on these insights, proposes an improved modulation strategy to reduce losses and optimize system efficiency. Furthermore, a comprehensive loss model of the converter topology is developed. Loss evaluations based on this model indicate that the 7L topology, which integrates Si-IGBTs and SiC-MOSFETs in a hybrid device solution, achieves lower losses while balancing cost-effectiveness, ultimately attaining an efficiency exceeding 97%. Compared to conventional ANPC-based solutions, this approach offers significant performance advantages. Specifically, compares and analyzes the efficiency and loss distribution of two drive solutions, providing a valuable reference for engineers and researchers in the future development of electric aircraft propulsion systems.