High-Performance HVDC is a research project funded by the Federal Ministry for Economic Affairs and Climate Action aimed at improving the efficiency of converters for high-voltage direct current (HVDC) transmission. The most significant factor for enhancing efficiency and reducing the investment costs of HVDC converters is the reduction of the number of series-connected submodules. The series number is determined by the blocking voltage of the power semiconductors used.

To achieve the desired savings, a series of innovative solutions must be researched. The converter must be suitable for a higher voltage per submodule, the submodules must be reinforced for higher operating voltage, but most importantly – and this is the central innovation – the blocking voltage of the IGBT modules must be increased from 4500 V to 6500 V without significantly increasing the losses.

To reach this goal, fundamental research is required in several areas. The chip technology of IGBTs and diodes, the packaging and interconnection technology within the module, and the control technology must all be substantially improved and continuously evaluated for their benefits and feasibility for future HVDC systems, and co-optimized.

The focus of the work at the University of Rostock is on the investigation of new control concepts. This includes examining how the turn-off losses of the IGBT can be reduced through a desaturation pulse, how an IGBT designed specifically for this purpose must be configured, and what potential this offers for optimizing the conduction losses of the IGBT. By controlling the IGBT depending on the operating point, the robustness reserves can be utilized, which arise because the switching speed of the IGBT must be designed for the highest DC link voltage and the most unfavorable load current, but the loss-relevant continuous operation points have a significantly lower DC link voltage.

Additionally, the university is researching a novel concept of a diode controllable via a gate connection. These investigations are conducted using device simulation.