Modular Multilevel Power Converters for Medium Voltage Applications

The Power Electronics research team from the School of Engineering at the University of Edinburgh is now looking to a recruit a high calibre PhD candidate to work on the topic of Modular Multilevel Converters; their design, control, operation and general optimization. This project aims to transpose the modular power converters outside of their inceptual HVDC market into medium voltage ratings where their positive characteristics (e.g. high waveform quality, high power efficiency) can support the increase in demand for power conversion applications, typically in distribution networks and electric drives. This means that aspects such as power density, passive and active components, overall power efficiency, control systems, and performance under widely-varying conditions must be thoroughly re-examined.

Over the two last decades, Modular Multilevel Power Converters have revolutionised the HVDC sector, delivering scalable, highly-controllable converter structures, which delivered improved performances in terms of waveform quality and power efficiency. The challenging requirements imposed on HVDC converters meant that large research efforts have been put on the electrical arrangement of all these devices, ultimately resulting in the inception of a new building block, called Sub-Modules (SM). SMs can be stacked, yet individually controlled forming modular power converters able to generate high quality waveforms at high power efficiency.

This PhD project consists in studying the state-of-the-art modular power converter technology applied to medium voltage applications, specifically aimed for distribution grid or electrical drive/machine applications. The research will identify key application areas and potential gains from the use of modular power converters, and address key barriers (e.g. number of levels, SM voltage, or modulation strategy) to their adoption. This project will include the development of new power electronics designs and converter operating principles based on Modular Power Converter technology. The objective is to bring some of the benefits of modular technology into medium voltage applications while aiming for low overall volume, high power efficiency, good thermal management, low EMI emission, and fault-resilient operation. The PhD student will be expected to design and build of hardware experiment to support the concepts developed in theory and tested in simulation.