Abstract

This manuscript investigates the potential of Integrated Gate-Commutated Thyristors (IGCT) for Modular Multi-Level Converters (MMC). After a theoretical analysis of the advantages of IGCTs regarding losses, we investigate their switching operation experimentally. In particular, we focus on di=dt limiting inductance and RCD-clamp reduction/suppression using plastic module silicon (Si) fast recovery diodes and silicon carbide (SiC) diodes in an MMC submodule. This study aims to explore improvements for the MMC, focusing on using different semiconductors in the MMC submodule.

This Ph.D. manuscript contains:

• An analysis of existing HVDC MMC Submodules and their technologies.
• A review on the IGCT: semiconductor structure, types and features.
• An assessment of the interest of the IGCT in HVDC MMC Submodules and losses comparison with IGBTs, using MMC-specific figures-of-merit created in this thesis.
• An assessment of the works on limiting di=dt inductor size reduction.
• A double pulse test design with specific structure imitating an MMC submodule.
• A review and an analysis of the PiN diode failure modes.
• Double pulse tests with fast recovery diode in plastic module with successful attempts to reduce and suppress the limiting di=dt inductor (up to 2400V/1800A and 2000V/2400A).
• The packaging of High-Voltage (10kV) High-Current (50A) SiC PiN diode dies (1cm²), test with IGCT in the same setup, with successful attempts to reduce and suppress the limiting di=dt inductor (up to 2400V/100A and 2000V/150A), and analysis of the specificities of the SiC diode in that setup.

Thesis director: Cyril Buttay (Ampère)

Thesis co-director: Eric Vagnon (Ampère)