The New High Reliable Press Pack IGBT for Modular Multilevel Converter in VSC-HVDC Applications

Abstract

In today's VSC-HVDC transmission lines, the Modular Multilevel Converter technology (MMC) becomes the mainstream as it decreases system complexity greatly. Recently Press Pack IGBT (PPI) has come into focus as a preferred realization for high power rating VSC-HVDC stations, it could offer the highest current rating IGBTs and advanced features in reliability. The paper introduces a new design of Press Pack IGBT with several innovative improvements, which are based on the application demands from VSC-HVDC systems. It is designed with hermetic sealed ceramic housing to avoid environmental erosion and could provide a robust feature of short circuit failure mode (SCFM) even enduring the discharge current from DC-link capacitor in case of arm short through. The PPI could be connected with an external Free-Wheeling Diodes (FWD), a higher current diode for the low side, to reduce the conduction loss and handle the surge current from the system and a lower current diode for high side to save cost. By that, customers are enabled to realize a cost-effective half-bridge stack by selecting different current rating devices in a sub-module design based on system requirements.