Highly Dynamic, Precise and Flexible Current Source for Plasma Research and Accelerators

Georgios Tsolaridis and Jürgen BielaProject Nr: 25197.1 PFEN-I

Outline

• Introduction

• Proposed Topology

• Full System Simulations

• Future Work

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Introduction– Applications

• Application areas:− Driving of septum/bumper magnets− Medical applications (e.g. MRI)− Arc/Plasma investigation for next

generation HVDC circuit breakers

• Specifications for HVDC breakers:− Emulation of fault currents in DC grids Arbitrary current source

− 30 kA output current @ 10 kV− > 200 A/μs current gradient− Up to 10 ms pulse length

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• Output voltage ±10 kV• Pulsed current 30 kA• DC current 20 kA• Current gradient > 200 A/µs • Pulse length 10 ms• Current ripple < 0.1% • Possible loads R, L & arc• Waveform Arbitrary• High Repeatability• High Modularity

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Introduction – Full System Specifications

Introduction - Target System Specifications

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Single Stack Source

Output voltage ±10 kV

Output current 1.5 kA

Current gradient >10 A/μs

Current ripple <1 %

DC current 1 kA

Full Scale Source

Output voltage ±10 kV

Output current 30 kA

Current gradient >200 A/μs

Current ripple <0.1 %

DC current 20 kA

• System concept− Current-shaping converter

• Interleaved, high fs, 2-level, low-voltage− Step voltage source

• Modular Multi-Level Marx-Type Converter

Proposed Topology - Operation Principle

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Proposed Topology – Current Shaping Converter

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• Multi-phase buck-type current shaping converter– Output current: 0 .. 1.5 kA– Output voltage: 0 .. 550 V– Interleaving Current ripple reduction

– High switching frequencySiC MOSFET

Proposed Topology – Marx Type Modular Multilevel Converter

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• Modular Multilevel Marx Converter M3TC– Staircase voltage– H-bridge → Bipolar

voltage ±10kV– Low switching frequency

→ slow dynamics– High capacitance value

needed• Film capacitors

selected (reliability)• Smaller energy

density larger volume

Hybrid Multiphase Controller*

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*G. Tsolaridis and J. Biela “Adaptive Hybrid Control Concept for Multiphase DC-DC Converters”, IEEE ECCE, Cincinnati, Ohio, USA 2017

• Transients Adaptive hysteresis controller

• Steady State PI controller

+ Phase shifting control Interleaving (low ripple)

• Benefits: Time-optimal transient response Excellent disturbance rejection Design simplicity Good steady state performance Very low current ripple

Simulation Results : Arbitrary waveform generation (RL load: 1 Ω – 10 μH)

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Slow ramp/Sinusoidal 200Hz• PI mode enabled• Min. ripple during the

transient

Pulse transient• Hysteretic mode• Max. achievable current

gradient

Simulation Results: Inductive Load – Preliminary Results

• Assumptions− 100 µH load inductance− < 3 kV max. output voltage

• Load inductor Low ripple• Operation could be optimized for

well-defined loads• Preliminary results

− Dynamics depend on # of stages

− Ripple/overshoot could be optimized

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Arc measurement by High Voltage Laboratory/ETH Zurich

Challenge: Dynamic Behavior of Load (Arcs)

• Arcs Extreme load fluctuations• Chaotic waveform of arc voltage• High frequency oscillations Highly dynamic control required

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Simulation Results: Performance under highly fluctuating load*

• Arc-Load:− Behavioral arc model− Measurement-based model− Stochastic changes

− > 250 V/µs− > 400% change in R-value

• Resulting current− Load current: ± 10%

*G. Tsolaridis and J. Biela “Modular, Highly Dynamic and Ultra-Low Ripple, Arbitrary Current Source for Plasma Research”, IEEE PPC, Brighton, UK 2017

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Arc measurement by High Voltage Laboratory/ETH Zurich

Future Work

• List of publications:

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3. G. Tsolaridis and J. Biela “Modular, Highly Dynamic and Ultra-Low Ripple, Arbitrary Current Source for Plasma Research”, IEEE PPC, Brighton, UK 2017

2. G. Tsolaridis and J. Biela “Adaptive Hybrid Control Concept for Multiphase DC-DC Converters”, IEEE ECCE, Cincinnati, Ohio, USA 2017

1. G. Tsolaridis and J. Biela “Hybrid Control Concept for Highly Dynamic Buck Converter Systems”, IEEE EPE, Warsaw, Poland 2017

• Development of the prototype system• Validation of the dynamic control system• Data synchronization/exchange• Advanced charging concept• Optimization of

• Dynamic behavior• Robust control• Repeatability

Prototype of previous concept

Thank you for your attention