Past Projects
The Faraday effect describes the influence of a magnetic field on the polarisation state of polarised light that is propagated through a magneto-optical (MO) medium. Depending on the magnitude of this magnetic field and a material characteristic of the MO-material, the Verdet constant, the plane of polarisation of linearly polarised light is rotated by an angle θ. After the optical modulation by the MO-material, the polarisation state is retrieved by an analyser stage, consisting of multiple linear polarisers, quarter-wave plates and optical detectors (photodiode, transimpedance analysers) and digitally evaluated.
In recent years, HVDC transmission gained increased interest due to the need for offshore and long-distance energy transmission with low losses. In addition, VSC enable a power reversal without the need of a voltage reversal, which is a first step to a meshed multi-terminal DC grid with low losses. A key requirement in such a DC-grid is the ability to interrupt rapidly fault currents and disconnect faulty parts of the grid. Since classical AC-CB cannot be used due to the lack of a natural zero current crossing, new DC circuit breaker (DC-CB) are developed.
High performance power electronic systems serving as high current power supplies are nowadays used in a wide range of application areas: from diagnostics and cancer treatment in the medical world to fundamental research activities in the physics world, and from plasma confinement in fusion energy activities to engineering research activities for the future of HVDC electric grid. These systems are usually designed specifically for the needs of the particular application they are intended to be used for, as they often need to fulfill strict specifications.
Pulsed-power techniques have been successfully applied in various areas such as medical treatment, food processing, military equipment, plasma generation and particle accelerator systems. Today, more and more pulse modulators are based on power semiconductor devices instead of hard tube devices, which have been commonly used as high-power electrical switch. The reason for this is the increasing power handling capability and robustness of modern semiconductors. In addition, these semiconductor devices enable the pulse to be turned off in case of faults and are not subject to single source issues.
The objective of this research project is the implementation of an MMC based active rectifier for the generation of test voltages in the medium voltage laboratory of the Laboratory for High Power Electronic Systems (HPE). The rectifier will be fed by the 9 kV AC grid and deliver up to 250 kW or 30 A (DC) in a DC voltage range from zero to 35 kV. It will be realized with 90 modules (15 per MMC arm) operating at a maximum module voltage of 2.2 kV.
Accurate & fast models of the transformer leakage inductance are crucial for optimisation-based design of galvanically isolated power electronic converters. These converters are key elements in several important applications such as photovoltaics, traction applications, and grid control. Power electronic converters are usually designed with optimisations that create up to several ten thousands of virtual prototypes and calculate their physical properties such as the transformer leakage inductance. Due to the high amount of virtual prototypes, the models need to be rapidly executable as well as accurate to deliver results within a reasonable amount of time.
