Averaged models and their control for three-phase modular multipoint converters

Duration: 1.5.2019 - 31.12.2023

The project is funded by the German Research Foundation(DFG-GEPRIS) and deals with modeling methods for cell-based power converters, such as the circuit known as a modular multilevel converter (MMC).

As is also the case with other power electronic systems, it can also be observed for modular multipoint converters that the variables describing the process change within very different time horizons, so that one often speaks of "fast" and "slow" changing variables. It has proven to be expedient for the control and regulation design to pick out only the relevant temporal context and, on the one hand, to neglect the dynamics of "fast" changing variables and, on the other hand, to consider "slower" changing variables as constant. In order to enable a model-based design of control algorithms, models are required that are able to describe the characteristic behavior in the selected temporal context. This problem is the focus of the present project. Special attention is paid to modeling the behavior of the average energy stored in the branches, which is particularly challenging for cell-based topologies, since the branch energies are not constant even in stationary working regimes.

Another focus of the project is the design and practical testing of model-based control and regulation methods for modular multi-point converters.

The interactive visualization was created in 2023 as part of Mr. Alexander Döge's research internship with the kind support of Gunther Kreuzberger from the Department of Virtual Worlds and Digital Games at TU Ilmenau.

[1] Gui, Q., Fehr, H., Gensior, A.:"Energy Control of Modular Multilevel Converters for Drive Applications at Low Frequency Using General Averaging" in IEEE Transactions on Power Electronics, Vol. 39(5), 2024, DOI: 10.1109/tpel.2024.3360000

[2] Gui, Q., Fehr, H., Gensior, A.: "Optimized Stationary Operating Regime and Common-Mode Voltage Design for Modular Multilevel Converters in Drive Applications at High Frequency" in 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), 2023, DOI: 10.23919/EPE23ECCEEurope58414.2023.10264464

[3] Gui, Q., Fehr, H., Gensior, A.: "Stability Assessment and Optimization of MMC Energy Balancing for Drive Applications at Standstill Using an Averaging Approach" in 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe), 2022, ieeexplore.org

[4] Fehr, H., Gensior, A.:"MMC Stationary Operating Regimes in Case of Periodic Power Demand on the DC Side" in IEEE Transactions on Power Electronics, Vol. 37(7), 2022, DOI: 10.1109/tpel.2022.3143318

[5] Gensior, A., Fehr, H.: "Modeling and Energy Balancing Control of Modular Multilevel Converters Using Perturbation Theory for Quasi-Periodic Systems" in IEEE Transactions on Power Electronics, Vol. 36(2), 2021, DOI: 10.1109/tpel.2020.3008317

[6] Lopez, M., Fehr, H., Perez, M., Gensior, A.: "Pareto Frontier of the Arm Energy Ripple and the Conduction Losses of a Modular Multilevel Converter" in energies, Vol. 14(2), 2021, DOI: 10.3390/en14020392

[7] Lopez, M., Fehr, H.: "Matlab Scripts for MMC Pareto Optimization", Dresden University of Technology, DOI: 10.25368/2020.125