Power Converter Characteristics Design & Operation Responsibles Power Converter Architecture Power Part Control Part

Magnet Protection Power Converter Components Magnet Types Machine Installation Production Contract & Contact History

Power Converter Characteristics

Design & Operation Responsibles

Responsibles:	Serge PITTET
	Ludovic CHARNAY
	CERN SY-EPC-LPC

Power 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.

Power Converter simplified Architecture .ppt or .vsdx

Power 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 Part simplified Architecture / Topology .vsd

Typical Curves

Control 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.

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

Magnet 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.

  

  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 output mid-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 100 Ohms earthing resistor in series with a 0.1 A fuse connects the mid-point 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 5 mA maximum allowed. The fuse (0.1 A fast) is provided to limit damage risk on the circuit side in any case and mode (active / passive).

  

  Earthing System simplified schematic .pptx

Power Converter Components

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

• Power Module
  • 2x Current sensor: PCB mount DCCT
  • Digital Controller: FGC4

Magnet Types

Machine Installation

Installation procedure

Production Contract & Contact History

Developped	CERN SY-EPC-LPC
	2021
	Serge PITTET
	Ludovic CHARNAY
Production	-	xx MEXICO Power Converters xx MEXICO Power Converters
Current requests	MEXICO12 Power Converters	003+1 for AD consolidation
	MEXICO25 Power Converters	007+2 for AD consolidation
Pending requests	MEXICO12 Power Converters	008+2 for LEIR consolidation
	MEXICO25 Power Converters	012+2 for AD trims consolidation 040+8 for LEIR consolidation 008+2 for LINAC4 consolidation 004+2 for LINAC4 source test stand
	MEXICO50 Power Converters	040+6 for AWAKE 2 Electron Line 017+3 for AWAKE 2 Helicon Plasma Source 016+4 for LEIR consolidation

Converter Circuit Names