---
_id: '29939'
abstract:
- lang: eng
  text: In this paper, a full-bridge modular multilevel converter (MMC) and two half-bridge-based
    MMCs are evaluated for high-current low-voltage e.g. 100 - 400V DC-applications
    such as electrolysis, arc welding or datacenters with DC-power distribution. Usually,
    modular multilevel converters are used in high-voltage DC-applications (HVDC)
    in the multiple kV-range, but to meet the needs of a high-current demand at low
    output voltage levels, the modular converter concept requires adaptations. In
    the proposed concept, the MMC is used to step-down the three-phase medium-voltage
    of 10kV, and provide up to 1 MW to the load. Therefore, each module is extended
    by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage
    range of 142 - 220V and to provide galvanic isolation. The six-arm MMC converter
    with half-bridge modules can be simplified and optimized by removing three arms,
    and thus halving the number of modules. In addition, the module voltage ripple
    and capacitor losses are decreased by 22% and 30% respectively. By rearranging
    the components of the half-bridge MMC to build a MMC consisting of grid-side full-bridge
    modules, the voltage ripple is further reduced by 78% and capacitor losses by
    64%, while ensuring identical costs and volume for all MMCs. Finally, the LLC
    resonant converter is designed for the most efficient full-bridge MMC. The LLC
    can not operate at resonance with a fixed nominal module voltage of 770V because
    the output voltage is varying between 142 - 220V. By decreasing the module voltage
    down to 600V, additional points of operation can be operated in resonance, and
    the remaining are closer to resonance. The option to decrease the module voltage
    down to 600V, increases the number of required modules per arm from 12 to 15,
    which requires to balance the losses of the LLCs and the grid-side stages.
author:
- first_name: Roland
  full_name: Unruh, Roland
  id: '34289'
  last_name: Unruh
- first_name: Frank
  full_name: Schafmeister, Frank
  id: '71291'
  last_name: Schafmeister
- first_name: Joachim
  full_name: Böcker, Joachim
  id: '66'
  last_name: Böcker
  orcid: 0000-0002-8480-7295
citation:
  ama: 'Unruh R, Schafmeister F, Böcker J. Evaluation of MMCs for High-Power Low-Voltage
    DC-Applications in Combination with the Module LLC-Design. In: <i>2020 22nd European
    Conference on Power Electronics and Applications (EPE’20 ECCE Europe)</i>. IEEE;
    2020. doi:<a href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">10.23919/epe20ecceeurope43536.2020.9215687</a>'
  apa: Unruh, R., Schafmeister, F., &#38; Böcker, J. (2020). Evaluation of MMCs for
    High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design.
    <i>2020 22nd European Conference on Power Electronics and Applications (EPE’20
    ECCE Europe)</i>. 22nd European Conference on Power Electronics and Applications
    (EPE’20 ECCE Europe), Lyon, France. <a href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687</a>
  bibtex: '@inproceedings{Unruh_Schafmeister_Böcker_2020, title={Evaluation of MMCs
    for High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design},
    DOI={<a href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">10.23919/epe20ecceeurope43536.2020.9215687</a>},
    booktitle={2020 22nd European Conference on Power Electronics and Applications
    (EPE’20 ECCE Europe)}, publisher={IEEE}, author={Unruh, Roland and Schafmeister,
    Frank and Böcker, Joachim}, year={2020} }'
  chicago: Unruh, Roland, Frank Schafmeister, and Joachim Böcker. “Evaluation of MMCs
    for High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design.”
    In <i>2020 22nd European Conference on Power Electronics and Applications (EPE’20
    ECCE Europe)</i>. IEEE, 2020. <a href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687</a>.
  ieee: 'R. Unruh, F. Schafmeister, and J. Böcker, “Evaluation of MMCs for High-Power
    Low-Voltage DC-Applications in Combination with the Module LLC-Design,” presented
    at the 22nd European Conference on Power Electronics and Applications (EPE’20
    ECCE Europe), Lyon, France, 2020, doi: <a href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">10.23919/epe20ecceeurope43536.2020.9215687</a>.'
  mla: Unruh, Roland, et al. “Evaluation of MMCs for High-Power Low-Voltage DC-Applications
    in Combination with the Module LLC-Design.” <i>2020 22nd European Conference on
    Power Electronics and Applications (EPE’20 ECCE Europe)</i>, IEEE, 2020, doi:<a
    href="https://doi.org/10.23919/epe20ecceeurope43536.2020.9215687">10.23919/epe20ecceeurope43536.2020.9215687</a>.
  short: 'R. Unruh, F. Schafmeister, J. Böcker, in: 2020 22nd European Conference
    on Power Electronics and Applications (EPE’20 ECCE Europe), IEEE, 2020.'
conference:
  end_date: 2020-09-11
  location: Lyon, France
  name: 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE
    Europe)
  start_date: 2020-09-07
date_created: 2022-02-21T16:33:14Z
date_updated: 2022-02-21T17:00:16Z
department:
- _id: '52'
doi: 10.23919/epe20ecceeurope43536.2020.9215687
keyword:
- Multilevel converters
- Resonant converter
- High voltage power converters
- ZVS Converters
- Combination MMC LLC
language:
- iso: eng
main_file_link:
- url: https://ieeexplore.ieee.org/abstract/document/9215687
publication: 2020 22nd European Conference on Power Electronics and Applications (EPE'20
  ECCE Europe)
publication_status: published
publisher: IEEE
status: public
title: Evaluation of MMCs for High-Power Low-Voltage DC-Applications in Combination
  with the Module LLC-Design
type: conference
user_id: '34289'
year: '2020'
...
---
_id: '29880'
abstract:
- lang: eng
  text: Although there are numerous design methodologies for the LLC resonant converter,
    they often do not consider the possibility of input voltage adjustment. In the
    proposed concept, a modular multi-level converter (MMC) is used to step-down the
    three-phase medium voltage of 10 kV, and provide up to 1 MW of pure DC power to
    the load consisting of electrolyzers for hydrogen generation. Therefore, each
    module is extended by an LLC resonant converter to adapt to the specific electrolyzers
    DC voltage range of 142...220 V and to provide galvanic isolation. In order to
    achieve a high efficiency for a wide range of load conditions, the input voltage
    of the LLC converter is adjusted between 600 V and 770 V while operating at resonance
    or close to resonance. The parameters of the 11kW LLC resonant converter with
    an integrated leakage inductance are systematically optimized to maximize the
    efficiency for all loads while achieving zero-voltage switching. For a fast estimation
    of eddy current losses, a new method is proposed, which uses a single FEM simulation
    to fit newly developed loss equations. The calculated average efficiency is 97.8%.
    The prototype of the LLC converter reaches a peak efficiency of over 98% at resonance
    at half load which is similar to the precalculated value.
author:
- first_name: Roland
  full_name: Unruh, Roland
  id: '34289'
  last_name: Unruh
- first_name: Frank
  full_name: Schafmeister, Frank
  id: '71291'
  last_name: Schafmeister
- first_name: Joachim
  full_name: Böcker, Joachim
  id: '66'
  last_name: Böcker
  orcid: 0000-0002-8480-7295
citation:
  ama: 'Unruh R, Schafmeister F, Böcker J. 11kW, 70kHz LLC Converter Design with Adaptive
    Input Voltage for 98% Efficiency in an MMC. In: <i>2020 IEEE 21st Workshop on
    Control and Modeling for Power Electronics (COMPEL)</i>. IEEE; 2020. doi:<a href="https://doi.org/10.1109/compel49091.2020.9265771">10.1109/compel49091.2020.9265771</a>'
  apa: Unruh, R., Schafmeister, F., &#38; Böcker, J. (2020). 11kW, 70kHz LLC Converter
    Design with Adaptive Input Voltage for 98% Efficiency in an MMC. <i>2020 IEEE
    21st Workshop on Control and Modeling for Power Electronics (COMPEL)</i>. <a href="https://doi.org/10.1109/compel49091.2020.9265771">https://doi.org/10.1109/compel49091.2020.9265771</a>
  bibtex: '@inproceedings{Unruh_Schafmeister_Böcker_2020, title={11kW, 70kHz LLC Converter
    Design with Adaptive Input Voltage for 98% Efficiency in an MMC}, DOI={<a href="https://doi.org/10.1109/compel49091.2020.9265771">10.1109/compel49091.2020.9265771</a>},
    booktitle={2020 IEEE 21st Workshop on Control and Modeling for Power Electronics
    (COMPEL)}, publisher={IEEE}, author={Unruh, Roland and Schafmeister, Frank and
    Böcker, Joachim}, year={2020} }'
  chicago: Unruh, Roland, Frank Schafmeister, and Joachim Böcker. “11kW, 70kHz LLC
    Converter Design with Adaptive Input Voltage for 98% Efficiency in an MMC.” In
    <i>2020 IEEE 21st Workshop on Control and Modeling for Power Electronics (COMPEL)</i>.
    IEEE, 2020. <a href="https://doi.org/10.1109/compel49091.2020.9265771">https://doi.org/10.1109/compel49091.2020.9265771</a>.
  ieee: 'R. Unruh, F. Schafmeister, and J. Böcker, “11kW, 70kHz LLC Converter Design
    with Adaptive Input Voltage for 98% Efficiency in an MMC,” 2020, doi: <a href="https://doi.org/10.1109/compel49091.2020.9265771">10.1109/compel49091.2020.9265771</a>.'
  mla: Unruh, Roland, et al. “11kW, 70kHz LLC Converter Design with Adaptive Input
    Voltage for 98% Efficiency in an MMC.” <i>2020 IEEE 21st Workshop on Control and
    Modeling for Power Electronics (COMPEL)</i>, IEEE, 2020, doi:<a href="https://doi.org/10.1109/compel49091.2020.9265771">10.1109/compel49091.2020.9265771</a>.
  short: 'R. Unruh, F. Schafmeister, J. Böcker, in: 2020 IEEE 21st Workshop on Control
    and Modeling for Power Electronics (COMPEL), IEEE, 2020.'
conference:
  end_date: 2020-11-12
  start_date: 2020-11-09
date_created: 2022-02-18T16:29:08Z
date_updated: 2024-11-28T14:19:07Z
department:
- _id: '52'
doi: 10.1109/compel49091.2020.9265771
keyword:
- Full-bridge
- High voltage power converters
- LLC resonant converter
- Multilevel converters
- ZVS Converters
language:
- iso: eng
main_file_link:
- url: https://ieeexplore.ieee.org/abstract/document/9265771
publication: 2020 IEEE 21st Workshop on Control and Modeling for Power Electronics
  (COMPEL)
publication_identifier:
  unknown:
  - 978-1-7281-7160-9
publication_status: published
publisher: IEEE
quality_controlled: '1'
status: public
title: 11kW, 70kHz LLC Converter Design with Adaptive Input Voltage for 98% Efficiency
  in an MMC
type: conference
user_id: '34289'
year: '2020'
...