topPower Converter Characteristics

Picture of the converter
CANCUN Cern Acdc Narrow CoNverter
Power In 3 x 400V with Neutral / 2.75A
Power Out (CANCUN 50)
RPAAN (CANCUN 50) (+/- 50A, +/-30V)
RPAAO (CANCUN 20) (+/- 20A, +/-75V)
RPAEH (CANCUN 100) (+/- 100Apeak, +/- 50Arms, +/-30V)
Converter Type 4 Quadrant
Control type FGC3 / Ethernet+
Current Accuracy 20 ppm@ 30 mn
20 ppm@ 24 h
100 ppm@ 1 year
(1 ppm=50uA=0.05mA)
Voltage Ripple 10 mVrms@ f=20Hz-1kHz
60 mVrms@ f=1kHz-130kHz
7 mVrms@ f=130kHz-5MHz

topDesign & Operation Responsibles

Responsibles: Serge PITTET Serge PITTET

topPower Converter Architecture

This Power Converter is used in Injector Machines to power warm magnets, for DC or pulse applications.

Different parts were designed and produced separately, Power Converter being finally integrated in a housing rack, with 3 main parts:

  • High Precision Current sensors (DCCTs), able to measure DC or pulse current at the required precision.
  • Power Part: Power Rack and its removable Power Module
  • A Digital Controller (FGC) using Ethernet bus in charge of:
    • The high level control from and to the Cern Control Room
    • The high precision digital current loop
    • Collecting and reporting all status, faults, and measurements from all the different parts to the remote services, for diagnostic and operation purposes.
Simplified Schematic

Power Converter simplified Architecture .ppt or .vsdx


topPower Part

Voltage Source is based on a full bridge phase shifted topology followed by a 4 quadrant switching stage to allow the 4 quadrant operation.

One DCCT is used for the high precision current loop (FGC), and is located directly in the voltage source, even if not used by it to operate as a pure voltage source.

Converter is compatible with 19'' standard dimensions.

Power In 3 x 400V with Neutral / 2.75A
Power Out (CANCUN 50) 1200W max (+/- 50A +/-30V)
Power Out (CANCUN 20) 1200W max (+/- 20A +/-75V)
Cooling type Fans
Converter Weight Power Module ............ 29 kg (FGC Included)
Simplified Schematic

Power Part simplified Architecture / Topology .vsd


Typical Curves

Output Voltage Ripple TBD

topControl Part

Control & regulation principles are summarized in a detailled schematics representating only the part involved in the output current regulation scheme. FGC3 control can adapt quite easily with different possible scenarios.

Detail FGC Regulator Vol.Sour.

I.Loop, I.sensor = power    -    I.Loop=fgc, I.sensor=power    -    I.Loop=fgc, I.sensor=external

Regulation Control simplified schematic .vsd

High precision current control loop is managed by the digital controller called FGC (Function Generator Controller). This unit includes a high precision Sigma Delta Analog to Digital Converter which digitalize the analog current measurement coming from 1 or 2 Current sensors (DCCTs: DC current Transducer). Precision is then directly relying on sensor precision: current sensors, the ADCs, and the algorithm being used for the regulation loop. Voltage source is then used as a power amplifier, powering the load through a high bandwidth voltage loop.


topMagnet Protection

Power Converter is part of magnet protection scheme, even if not directly fully responsible of the monitoring and diagnostic of the magnet status. WIC (Warm Interlock Controller) can interlock Power Converter if magnet safety requires it.

Power Converter is then expected to:

  • Always ensure that external protection system can stop the Power Converter through a safe signal called Fast Abort.
  • Stop powering the load in safe way (handling the magnet energy even when stopping, through dedicated system called crowbar). This active system provides a safe resistive discharge path for magnet current (energy).
  • Monitor Earth current of the total circuit: converter + load (magnet and its DC cables), and take the right action if threshold reached.


  • Crowbar

    The system is based on a 200 mOhms power resistance connected to two mosfet which are closed when the converter is off or standby.

    Simplified Schematic

    Crowbar System simplified schematic .vsd

  • Earth System

    This system is based on a two modes detection system: Active (by default) and Passive (configurable). In Active mode, the load is polarized to +10 V versus earth on its negative output connexion point (common mode). This allows detecting any earthing leakage faulty condition, without the need to energise the circuit for allowing the detection system to operate. A 10 Ohms earthing resistor in series with a 1A fuse connects the negative polarity to earth, with this resistance being used as a current sensor (shunt) sensing the circuit earthing leakage current. The system monitors the earthing leakage current to a value of 50 mA maximum allowed. The fuse (1 A fast) is provided to limit damage risk on the circuit side in any case and mode (active / passive).

    Simplified Schematic

    Earthing System simplified schematic .vsd


topPower Converter Components

A power converter is actually a sum of different equipments under several different sections in the TE-EPC group. The modularity is a key factor for easier maintenance with regards to MTTR reduction.


topMagnet Types

corrector TBD


topMachine Installation

Installation procedure

Air losses Module @ P.nom (incl. FGCs) 350 Watts
Water losses Module @ P.nom (incl. FGCs) none
HIE Isolde Use 30+3 CANCUN_50 Power Converters
GPS-REX-Consolidation Use 1+0 CANCUN_50 Power Converters
Booster Use 16+2 CANCUN_50 Power Converters
16+2 CANCUN_100 Power Converters (Qstrips)
PS Use 4+0 CANCUN_20 Power Converters (XNO, XSK)
2+0 CANCUN_50 Power Converters (XSK)
100+2 CANCUN_20 Power Converters (QFN, QDN, QSK, DVT)
50+4 CANCUN_20 Power Converters (DHZ)
TT2 Use 4+1 CANCUN_50 Power Converters
AD Use 13+1 CANCUN_20 Power Converters
Elena Use 34+2 CANCUN_50 Power Converters (ring)
1+1 CANCUN_50 Power Converters (electron cooler)
Awake Use 3+1 CANCUN_50 Power Converters
Spares A7 7 CANCUN_20 Power Converters
4 CANCUN_50 Power Converters
0 CANCUN_100 Power Converters


topProduction Contract & Contact History

Developped LPC icon CERN TE-EPC-LPC
Production CB SVENDSEN A/S 38 CANCUN_50 Power Converters
2 CANCUN_20 Power Converters
  ASTI-AS 67 CANCUN_50 Power Converters
18 CANCUN_100 Power Converters
  AXXE 179 CANCUN_20 Power Converters
Pending requests CANCUN_50 Power Converters 001+0 for HELIOS (HIE-Isolde)
002+0 for NTOF

topConverter Circuit Names