MMC Output Power Enhancement with IGBT and Diode Desaturation Control

Abstract:
Desaturation Control allows advantageous trade-off combining low on-state voltage and low switching losses for silicon bipolar power devices. Especially desaturation control is very effective for high voltage devices suffering from high voltage drop and large amount of charge carriers in the drift zone. This paper discusses in detail the desaturation control of IGBTs and of gate controllable diodes (GCDs). TCAD simulations show up to 70% reduction in switching losses using 6.5 kV ultra-low saturation IGBTs and GCDs in combination with desaturation control. As a consequence, the output power of the Modular Multilevel Converter (MMC) with low VCE,sat IGBTs and gate controllable diodes inside, can be increased by a factor of up to 2.