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Fernqvist, G.

Paper Title Page
MOPAN070 Developments in High-precision Aspects of Power Converter Control for LHC 314
  • G. Fernqvist, M. C. Bastos, A. Cantone, Q. King
    CERN, Geneva
  The initial results from integration testing of the LHC magnet power converters revealed problems of low-frequency noise, settling time, drift with time and temperature, thermal management and EMC. These problems originated in the use of DSP, the A/D converter (ADC), the DC Current Transducer (DCCT) and their respective environments. This paper reports the methods used to improve the performance through hardware and software modifications and the results achieved.  
MOPAN071 Characteristics of Burden Resistors for High-precision DC Current Transducers 317
  • G. Fernqvist, P. Dreesen, G. Hudson
    CERN, Geneva
  • J. R. Pickering
    Metron, Norwich
  The DC current transducer (DCCT) and accompanying A/D converter determine the precision of a power converter in accelerator operation. In the LHC context this precision approaches 10-6. Inside the DCCT, a burden resistor is used to convert the current to an output voltage. The performance of this resistor is crucial for the accuracy, temperature behaviour, settling time and long-term drift of the DCCT. This paper reports on evaluations, a new parameter called "power coefficient" (PC) and test results from some different types of resistors available on the market.  
MOPAN072 High-precision Performance Testing of the LHC Power Converters 320
  • G. Fernqvist, M. C. Bastos, A. Cantone, P. Dreesen, O. Fournier, G. Hudson
    CERN, Geneva
  The magnet power converters for LHC were procured in three parts, power part, current transducers and control electronics, to enable a maximum of industrial participation in the manufacturing and still guarantee the very high precision (a few parts in 10-6) required by LHC. One consequence of this approach was several stages of system tests: factory reception tests, CERN reception tests, integration tests, short-circuit tests and commissioning on the final load in the LHC tunnel. The majority of the power converters for LHC have now been delivered, integrated into complete converters and high-precision performance testing is well advanced. This paper presents the techniques used for high-precision testing and the results obtained. It is also hoped to report results from the first sector commissioning.