| 1. |
- Högerl, Tobias, et al.
(författare)
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Battery Emulation for Battery Modular Multilevel Management (BM3) Converters and Reconfigurable Batteries with Series, Parallel and Bypass Function
- 2021
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Ingår i: 21st IEEE International Conference on Environment and Electrical Engineering and 2021 5th IEEE Industrial and Commercial Power System Europe, EEEIC / I and CPS Europe 2021 - Proceedings. ; , s. 1227-1234
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the emulation of lithium-ion battery cells/modules for the development and testing of battery modular multilevel management converters and any kind of reconfigurable battery systems with series, parallel and bypass function. The developed emulator is based on a buck converter type with an isolated input voltage supply. A circuit board with the form factor of two cylindrical 18650 battery cells was developed, which can function as a replacement of a real battery cell/module for a laboratory setup. In addition to the implemented safety mechanisms, such as over-current, over-voltage and short-circuit protection, a simplified electrical equivalent circuit model is implemented on the integrated micro controller. Thereby, the dynamic electrical behavior of any battery cell can be emulated with low deviations from its real battery behavior.
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| 2. |
- Kersten, Anton, 1991, et al.
(författare)
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Sensorless Capacitor Voltage Balancing of a Grid-Tied, Single-Phase Hybrid Multilevel Converter with Asymmetric Capacitor Voltages using Dynamic Programming
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. ; 2020-October, s. 4288-4293
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Konferensbidrag (refereegranskat)abstract
- This paper shows a sensorless capacitor voltage balancing control approach for a grid-connected, single-phase hybrid multilevel inverter based on an NPC main stage with a voltage stiff DC-link and an arbitrary number of H-Bridge modules (capacitor modules) with asymmetric capacitor voltages. Using nearest-level control, a model predictive control (MPC) approach with a prediction horizon of one time step is chosen to find an optimal switching-state combination among the redundant switching combinations to balance the capacitor voltages as quick as possible. Using the Lyapunov stability criterion, it is shown that an offline calculated optimal switching-state sequence for each discrete output voltage level can be used to operate the inverter without using any voltage sensors for the capacitor voltages. To validate the stability of the approach, a laboratory inverter with a resistive load is operated with the offline calculated optimal switching-state sequences and it is shown that the capacitor voltages converge to their desired reference voltages.
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| 3. |
- Kuder, Manuel, et al.
(författare)
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Capacitor Voltage Balancing of a Grid-Tied, Cascaded Multilevel Converter with Binary Asymmetric Voltage Levels Using an Optimal One-Step-Ahead Switching-State Combination Approach †
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel capacitor voltage balancing control approach for cascaded multilevel inverters with an arbitrary number of series-connected H-Bridge modules (floating capacitor modules) with asymmetric voltages, tiered by a factor of two (binary asymmetric). Using a nearest-level reference waveform, the balancing approach uses a one-step-ahead approach to find the optimal switching-state combination among all redundant switching-state combinations to balance the capacitor voltages as quickly as possible. Moreover, using a Lyapunov function candidate and considering LaSalle's invariance principle, it is shown that an offline calculated trajectory of optimal switching-state combinations for each discrete output voltage level can be used to operate (asymptotically stable) the inverter without measuring any of the capacitor voltages, achieving a novel sensorless control as well. To verify the stability of the one-step-ahead balancing approach and its sensorless variant, a demonstrator inverter with 33 levels is operated in grid-tied mode. For the chosen 33-level converter, the NPC main-stage and the individual H-bridge modules are operated with an individual switching frequency of about 1 kHz and 2 kHz, respectively. The sensorless approach slightly reduced the dynamic system response and, furthermore, the current THD for the chosen operating point was increased from 3.28% to 4.58% in comparison with that of using the capacitor voltage feedback.
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| 4. |
- Lohse, Benjamin, et al.
(författare)
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The Modular Multilevel Magnetic Stimulator: Energy-Efficiency, Pre-Charging and Overlap Protection
- 2021
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Ingår i: IECON 2021 - 47TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY. - 1553-572X. - 9781665435543
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Konferensbidrag (refereegranskat)abstract
- The technology of transcranial magnetic stimulation (TMS) enables to break new ground in medical research. It is suitable for different diagnostics, as well as therapeutic purposes, such as the treatment of depression or epilepsy, which are not fully explored yet. TMS devices that are currently available on the market offer a limited possibility for a targeted stimulation, due to their predefined voltage pulse shape. This paper presents a novel TMS device based on a multilevel inverter technology. Utilizing several cascaded sub-modules (built as H-bridges), arbitrary output waveforms can be discretely generated. At first, a theoretical part discusses how the energy efficiency of such a device can be increased by applying suitable control strategies and how it is possible to charge multiple sub-modules with only one auxiliary power supply. In addition, it is shown how to determine the required capacitance rating of a sub-module. Next, in the practical part, a designed prototype is presented and its current and voltage capabilities are verified, conducting 2.3 kA (peak-to-peak). In addition, the influence of different dead-times on the output voltage waveform is investigated. It is shown that the precise adjustment of the dead-time is crucial to ensure the proper switching of the required current without damaging the hardware.
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| 5. |
- Neukirchinger, Fabian, et al.
(författare)
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Where Transcranial Magnetic Stimulation is headed to: The modular extended magnetic stimulator
- 2021
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Ingår i: 21st IEEE International Conference on Environment and Electrical Engineering and 2021 5th IEEE Industrial and Commercial Power System Europe, EEEIC / I and CPS Europe 2021 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Transcranial magnetic stimulation (TMS) already suffered, even though first presented in 1985, a technical stagnation. Even though applications of stimulation patterns were optimized for treatment and research objectives, the technical buildup of transcranial magnetic stimulators only advances in terms of a reduced energy consumption, but never concerning the aspect of adjustable pulse shapes. This paper reviews prior technical advances of magnetic stimulators and their medical applications. Moreover, a novel multilevel stimulator is presented and it is analyzed how it could finally overcome the restriction of predefined pulse shapes. Finally,it is discussed how freely selectable pulse shapes might fundamentally change the way TMS is applied.
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| 6. |
- Schwitzgebel, Florian, et al.
(författare)
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Design and testing of a novel transcranial magnetic stimulator with adjustable pulse dynamics and high current capability (>2 ka) based on a modular cascaded h-bridge inverter topology
- 2021
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Ingår i: PCIM Europe Conference Proceedings. - 2191-3358. ; 2021-May, s. 206-213
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Konferensbidrag (refereegranskat)abstract
- Transcranial magnetic stimulation (TMS) is an important technology in neurological diagnostics and therapy. The limited output voltage shape of modern TM stimulators constrains the research about the targeted stimulation of individual brain parts. This paper introduces a novel TM stimulator based on a cascaded H-bridge inverter topology. Using a large number of sub-modules (e.g., ten), a nearly arbitrary output voltage waveform can be generated. Within the frame of this paper, the design and testing of an individual H-bridge module, using low-voltage MOSFETs, is explained in detail. To achieve a high current capability, the switching waveforms of the paralleled MOSFETs are synchronized by individual time delays introduced by an integrated CPLD. The H-bridge module is used for different experimental pulse tests. Using a DC link voltage of 180 V a maximum current peak of about 2.1 kA is achieved.
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