Load parameters used for the power converter

SIS100 dipole

Main parameters

The load maximum current was currently set to

FMT_LOAD_MAXIMUM_CURRENT='17e3'

The power converter is a two quadrant power converter. The power converter has two DCCT's. One for the regulation of the power converter and one for the software used for measurements. These have a little offset. This offset can add up. Thus allow for a little extra negative current.
power converter load description does not fully handle negative currents.

FMT_LOAD_MINIMUM_CURRENT='-10'

Resistance of the circuit including power converter internal resistance and lines to the magnet. This parameter was estimated comparing the voltage the power converter measured and the voltage it displayed as (pre) set voltage on an oscilloskop

FMT_LOAD_RESISTANCE='140e-6'

Constant inductance: orignally from calculations: then adjusted by matching the ramp voltage measured by the power converter to the set voltage of the power converter

FMT_LOAD_INDUCTANCE='0.5125e-3'

Saturation correction factors

The following parameters were used to correct the saturation effects:

• Nominal current: FMT_LOAD_NOMINAL_CURRENT=13100
• Start of saturation effect FMT_LOAD_THRESHOLD_CURRENT=8864
• Correction factor applied to I/FMT_LOAD_MAXIMUM_CURRENT
  • linear correction: FMT_LOAD_INDUCTANCE_CORRECTION_LINEAR='-0.0'
  • quadratic correction: FMT_LOAD_INDUCTANCE_CORRECTION_QUADRATIC='-0.2206'
  • cubic correction: FMT_LOAD_INDUCTANCE_CORRECTION_CUBIC='0.0195'

Script text

The above parameters would then be summed up by

FMT_LOAD_MAXIMUM_CURRENT='17e3'
# The power converter has two DCCT's. One for the regulation of the power converter
# and one for the software used for measurements. These have a little offset. 
# This offset can add up. Thus allow for a little extra negative current.
# power converter load description does not fully handle negative currents.
FMT_LOAD_MINIMUM_CURRENT='-10'

FMT_LOAD_RESISTANCE='140e-6'
# To be measured on the power converter
FMT_LOAD_INDUCTANCE='0.5125e-3'

# The following two parameters are used for the correction factors 
# to correct staturation effects.
# 
FMT_LOAD_NOMINAL_CURRENT='13100'
# Start of saturation effect
FMT_LOAD_THRESHOLD_CURRENT='8864'
# Correction factor applied to I/FMT_LOAD_MAXIMUM_CURRENT
FMT_LOAD_INDUCTANCE_CORRECTION_LINEAR='-0.0'
FMT_LOAD_INDUCTANCE_CORRECTION_QUADRATIC='-0.2206'
FMT_LOAD_INDUCTANCE_CORRECTION_CUBIC='0.0195'

STF Test Load

Main Parameters

These parameters were used when the rectangular solenoid was powered using the STF power converters

• inductance (in Henry): FMT_LOAD_INDUCTANCE='0.3e-3'
• resistance (in Ohm) : FMT_LOAD_RESISTANCE='400e-6'
• maximum current of the load FMT_LOAD_MAXIMUM_CURRENT='20e3'. Please be aware that the test load may only be powered DC to a current of ~14 kA!

​Correction Factors

The test load is an air coil and thus does not need a inductance saturation correction. It is deactivated setting the nominal current larger than the current the power converter can provide

• So the nominal current of the load was set to: FMT_LOAD_NOMINAL_CURRENT='21e3'
• Similarily the threshold current was set to a value larger than the power converter can provide: FMT_LOAD_THRESHOLD_CURRENT='21e3'
• To avoid any trouble all correction factors were set to 0:
  • linear correction: FMT_LOAD_INDUCTANCE_CORRECTION_LINEAR='-0.0'
  • quadratic correction: FMT_LOAD_INDUCTANCE_CORRECTION_QUADRATIC='-0.0'
  • cubic correction: FMT_LOAD_INDUCTANCE_CORRECTION_CUBIC='-0.0'

Script text

# STF test load (rectangular solenoid)
FMT_LOAD_INDUCTANCE='0.3e-3'


# including power converter setup
FMT_LOAD_RESISTANCE='400e-6'

FMT_LOAD_MAXIMUM_CURRENT='20e3'
FMT_LOAD_NOMINAL_CURRENT='21e3'
FMT_LOAD_THRESHOLD_CURRENT='21e3'

FMT_LOAD_INDUCTANCE_CORRECTION_LINEAR='-0.0'
FMT_LOAD_INDUCTANCE_CORRECTION_QUADRATIC='-0.0'
FMT_LOAD_INDUCTANCE_CORRECTION_CUBIC='-0.0'

A short circuit

A common test configuration is a short circuit: e.g. for testing current leads or other tests with a load of minimal inductance. Similar to the STF dummy load a set of parameters is chosen, sothat no inductance correction is used.

Main Parameters

The inductance is set to 0

FMT_LOAD_INDUCTANCE='0.0'

The resistance is equal to the internal resistance of the power conververter and its cables. A typical value for the STF cable length is

FMT_LOAD_RESISTANCE='140e-6'

The cabling at the PTF is shorter thus a good value of resistance is

FMT_LOAD_RESISTANCE='110e-6'

Ohm.

Correction Factors

The correction factors are the same as the correction factors used for the STF dummy load.

-- PierreSchnizer - 2016-11-29