Rugged MMC converter cell for high power applications

Abstract

A converter cell for a Modular Multilevel Converter (MMC) suitable for the Chain-Link Converter topology is presented. IGCT semiconductors are being used as the main switch technology thanks to features like · inherent stable Short Circuit Failure Mode (SCFM) capability · very low overall losses · superior load cycling capabilities. The cell makes use of a single thyristor switch to protect the cell against catastrophic damages in all relevant failure modes. The same thyristor enables continued operation of the chain-link converter after a single cell level failure. A comparison of losses in a STACOM application between IGBT plastic modules and hermetically sealed RC-IGCT press pack devices is presented.