---
_id: '34176'
abstract:
- lang: eng
  text: Cascaded H-bridge Converters (CHBs) are a promising solution in converting
    power from a three-phase medium voltage of 6.6 kV...30 kV to a lower DC-voltage
    in the range of 100 V...1 kV to provide pure DC power to applications such as
    electrolyzers for hydrogen generation, data centers with a DC power distribution
    and DC microgrids. CHBs can be interpreted as modular multilevel converters with
    an isolated DC-DC output stage per module, require a large DC-link capacitor for
    each module to handle the second harmonic voltage ripple caused by the fluctuating
    input power within a fundamental grid period. Without a zero-sequence voltage
    injection, star-connected CHBs are operated with approximately sinusoidal arm
    voltages and currents. The floating star point potential enables to utilize different
    zero-sequence voltage injection techniques such as a third-harmonic injection
    with 1/6 of the grid voltage amplitude or a Min-Max voltage injection. Both well-known
    methods have the advantage to reduce the peak arm voltage and thereby the number
    of required modules by 13.4 % (to √ 3 2). This paper proves analytically that
    the third-harmonic injection with 1/6 of the grid voltage amplitude reduces the
    second harmonic voltage ripple by only 15.1 % compared to no-voltage injection
    for unity power factor operation and balanced grid voltages. Then it is shown,
    that the Min-Max injection has the often overlooked advantage of reducing the
    second harmonic voltage ripple by even 18.8 %. By applying the here proposed zero-sequence
    voltage injection in saturation modulation, the second harmonic voltage ripple
    of the DC-link capacitors is reduced by even 24.3 %, while still requiring the
    same number of modules as the Min-Max injection. For a realistic number of reserve
    modules, the overall energy ripple in the DC-link capacitors is reduced by 40
    %.
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. Zero-Sequence Voltage Reduces DC-Link Capacitor
    Demand in Cascaded H-Bridge Converters for Large-Scale Electrolyzers by 40%. In:
    <i>24th European Conference on Power Electronics and Applications (EPE’22 ECCE
    Europe)</i>. IEEE; 2022.'
  apa: Unruh, R., Schafmeister, F., &#38; Böcker, J. (2022). Zero-Sequence Voltage
    Reduces DC-Link Capacitor Demand in Cascaded H-Bridge Converters for Large-Scale
    Electrolyzers by 40%. <i>24th European Conference on Power Electronics and Applications
    (EPE’22 ECCE Europe)</i>. 24th European Conference on Power Electronics and Applications
    (EPE’22 ECCE Europe), Hanover, Germany.
  bibtex: '@inproceedings{Unruh_Schafmeister_Böcker_2022, title={Zero-Sequence Voltage
    Reduces DC-Link Capacitor Demand in Cascaded H-Bridge Converters for Large-Scale
    Electrolyzers by 40%}, booktitle={24th European Conference on Power Electronics
    and Applications (EPE’22 ECCE Europe)}, publisher={IEEE}, author={Unruh, Roland
    and Schafmeister, Frank and Böcker, Joachim}, year={2022} }'
  chicago: Unruh, Roland, Frank Schafmeister, and Joachim Böcker. “Zero-Sequence Voltage
    Reduces DC-Link Capacitor Demand in Cascaded H-Bridge Converters for Large-Scale
    Electrolyzers by 40%.” In <i>24th European Conference on Power Electronics and
    Applications (EPE’22 ECCE Europe)</i>. IEEE, 2022.
  ieee: R. Unruh, F. Schafmeister, and J. Böcker, “Zero-Sequence Voltage Reduces DC-Link
    Capacitor Demand in Cascaded H-Bridge Converters for Large-Scale Electrolyzers
    by 40%,” presented at the 24th European Conference on Power Electronics and Applications
    (EPE’22 ECCE Europe), Hanover, Germany, 2022.
  mla: Unruh, Roland, et al. “Zero-Sequence Voltage Reduces DC-Link Capacitor Demand
    in Cascaded H-Bridge Converters for Large-Scale Electrolyzers by 40%.” <i>24th
    European Conference on Power Electronics and Applications (EPE’22 ECCE Europe)</i>,
    IEEE, 2022.
  short: 'R. Unruh, F. Schafmeister, J. Böcker, in: 24th European Conference on Power
    Electronics and Applications (EPE’22 ECCE Europe), IEEE, 2022.'
conference:
  end_date: 2022-09-09
  location: Hanover, Germany
  name: 24th European Conference on Power Electronics and Applications (EPE'22 ECCE
    Europe)
  start_date: 2022-09-05
date_created: 2022-12-02T12:47:38Z
date_updated: 2023-10-23T09:04:23Z
department:
- _id: '52'
keyword:
- Cascaded H-Bridge
- Solid-State Transformer
- Zero sequence voltage
- Third harmonic injection
- Capacitor voltage ripple
language:
- iso: eng
main_file_link:
- url: https://ieeexplore.ieee.org/abstract/document/9907278
publication: 24th European Conference on Power Electronics and Applications (EPE'22
  ECCE Europe)
publication_identifier:
  isbn:
  - 978-9-0758-1539-9
publication_status: published
publisher: IEEE
status: public
title: Zero-Sequence Voltage Reduces DC-Link Capacitor Demand in Cascaded H-Bridge
  Converters for Large-Scale Electrolyzers by 40%
type: conference
user_id: '34289'
year: '2022'
...