Predictive Control of Multilevel Inverters for Improving Performance and Efficiency in Energy Distribution and Drive Control

• Applicant: Professor Dr.-Ing. Ralph Kennel
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: from 2009 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 120076147

Multilevel converters produce output voltages which are much more similar to sinusoidal waveforms than those of standard 6-pulse inverters. In applications where sinusoidal waveforms are essential (e. g. power supplies of rural settlements, farms or electrical drives with low torque ripple requirements) this would save a lot of investment concerning output filters.The main disadvantages of multilevel inverters in comparison with standard inverters - preventing them from being applied very often in industry - are the higher number of power semiconductors and a more sophisticated control scheme.The blocking voltage of each power device in a multilevel inverter can be chosen smaller than in standard pulse inverters, as there are several power switches in series within each inverter leg. The prices of several power devices for low voltages are still higher than the price for a single high voltage power device. The price gap, however, decreases and even if it will not disappear completely, the application of multilevel converters becomes more probable due to the advantages mentioned above.The main goal of the project proposed by this application is to find a combination of multilevel converter topology with a predictive control strategy to provide an optimized system for three-phase sinusoidal output voltages.In difference to the opinion of some reviewers predictive control of power electronics is actually a highly interesting research topic - therefore the IEEE Transactions on Industrial Electronics have published a special issue on "Predictive Control" [24] in 2009. Furthermore, a workshop about this topic was conducted at Technische Universität München [21]. Additionally, a fundamental book about Model-based Predictive Control of drive systems was published by the applicant [25].In the same way predictive control strategies are in difference to the opinion of some reviewers useful not only for high power converters with low switching frequencies - especially in MPC strategies ([22], [23]) these criterions are one of several possibilities only to combine technical requirements in a so-called cost function to optimize the predictive control, respectively.According to the knowledge of the applicants there is no research project active in this area in Germany today. This application shall change the situation and contribute to Germany keeping close contact to internationalresearch developments.

• DFG Programme: Research Grants
• International Connection: South Africa
• Participating Person: Professor Hendrik du Toit Mouton