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A modular and compact long pulse modulator based on the SML topology for the ESS Linac

Fjelner Collins, Max LU and Martins, Carlos LU (2017) In IEEE Transactions on Dielectrics and Electrical Insulation 24(4). p.2259-2267
Abstract

The ESS Linac project, phase I, requires 12 long pulse klystron modulators with compact footprint, high pulse power and improved quality both on the output pulse waveform and on the input AC power line. Conventional long pulse modulators are typically based on HV pulse transformers and commonly exhibit poor efficiency, low power density, large footprint and cost, with still limited performance on pulse rise time, pulse flat-top accuracy and AC power line quality (flicker, current harmonic distortion, power factor). This paper presents the Stacked Multi-Level (SML) klystron modulator topology, a novel modular concept based on the association of several HV modules in series at their output, each formed by a high voltage and high-frequency... (More)

The ESS Linac project, phase I, requires 12 long pulse klystron modulators with compact footprint, high pulse power and improved quality both on the output pulse waveform and on the input AC power line. Conventional long pulse modulators are typically based on HV pulse transformers and commonly exhibit poor efficiency, low power density, large footprint and cost, with still limited performance on pulse rise time, pulse flat-top accuracy and AC power line quality (flicker, current harmonic distortion, power factor). This paper presents the Stacked Multi-Level (SML) klystron modulator topology, a novel modular concept based on the association of several HV modules in series at their output, each formed by a high voltage and high-frequency transformer, a HV diode rectifier bridge and a low pass filter. Each HV module is fed from a low voltage power electronic inverter at ground potential since the transformer provides the required galvanic isolation between primary and secondary windings. This topology is believed to better suit the application and better satisfy ESS requirements, directly addressing the mentioned shortcomings of conventional topologies. The development and validation of this new concept has included the design and construction of a reduced scale prototype with the potential of delivering long (3.5 ms) and high quality pulses (0-99% rise time <120 μs and flat top ripple <0.15%) with pulse amplitudes up to 115 kV and pulse power up to 2 MW, while maintaining excellent AC grid power quality (low flicker operation < 0.2%, sinusoidal current absorption with total harmonic distortion < 3%, and unitary power factor). The paper describes the main features of the topology and the main design aspects, presenting results both from simulation models, including parasitic elements, and from an experimental setup.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Accelerator power supplies, high voltage techniques, pulse generation, pulse power systems
in
IEEE Transactions on Dielectrics and Electrical Insulation
volume
24
issue
4
pages
9 pages
publisher
IEEE--Institute of Electrical and Electronics Engineers Inc.
external identifiers
  • scopus:85029815426
  • wos:000411003700036
ISSN
1070-9878
DOI
10.1109/TDEI.2017.006284
language
English
LU publication?
yes
id
bf699a4b-431a-41cf-a900-2c825507328f
date added to LUP
2017-10-09 14:10:02
date last changed
2018-01-16 13:22:00
@article{bf699a4b-431a-41cf-a900-2c825507328f,
  abstract     = {<p>The ESS Linac project, phase I, requires 12 long pulse klystron modulators with compact footprint, high pulse power and improved quality both on the output pulse waveform and on the input AC power line. Conventional long pulse modulators are typically based on HV pulse transformers and commonly exhibit poor efficiency, low power density, large footprint and cost, with still limited performance on pulse rise time, pulse flat-top accuracy and AC power line quality (flicker, current harmonic distortion, power factor). This paper presents the Stacked Multi-Level (SML) klystron modulator topology, a novel modular concept based on the association of several HV modules in series at their output, each formed by a high voltage and high-frequency transformer, a HV diode rectifier bridge and a low pass filter. Each HV module is fed from a low voltage power electronic inverter at ground potential since the transformer provides the required galvanic isolation between primary and secondary windings. This topology is believed to better suit the application and better satisfy ESS requirements, directly addressing the mentioned shortcomings of conventional topologies. The development and validation of this new concept has included the design and construction of a reduced scale prototype with the potential of delivering long (3.5 ms) and high quality pulses (0-99% rise time &lt;120 μs and flat top ripple &lt;0.15%) with pulse amplitudes up to 115 kV and pulse power up to 2 MW, while maintaining excellent AC grid power quality (low flicker operation &lt; 0.2%, sinusoidal current absorption with total harmonic distortion &lt; 3%, and unitary power factor). The paper describes the main features of the topology and the main design aspects, presenting results both from simulation models, including parasitic elements, and from an experimental setup.</p>},
  articleno    = {8035399},
  author       = {Fjelner Collins, Max and Martins, Carlos},
  issn         = {1070-9878},
  keyword      = {Accelerator power supplies,high voltage techniques,pulse generation,pulse power systems},
  language     = {eng},
  number       = {4},
  pages        = {2259--2267},
  publisher    = {IEEE--Institute of Electrical and Electronics Engineers Inc.},
  series       = {IEEE Transactions on Dielectrics and Electrical Insulation},
  title        = {A modular and compact long pulse modulator based on the SML topology for the ESS Linac},
  url          = {http://dx.doi.org/10.1109/TDEI.2017.006284},
  volume       = {24},
  year         = {2017},
}