SERVICE
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MAGNET POWER SUPPLY SYSTEM 8500
3.3.4.3. Auto Slew Rate Ramp Profile method.
With the”Auto Slew Rate Ramp Profile Method” an automatic ramp profile will be generated and
executed when issuing a new current set point. In other words, this feature acts like a software driven
slew rate controller.
Two shapes can be preselected. A cosines and a square shape. Which shape is selected, is given by
the Aux2 setting bit 4. 0=Cosines & 1=Square
Example:
If the power supply is at 10% output current, the slew rate is set to 1 second
(‘esc’<slopetime 1,1) and a set command “da 0,600000" is given the power supply will
start at 10% and run to 60% within ½ a second with the selected shape.
The positive and negative slew rate value can be set individually. Please refer to the SW manual
describing the “‘esc’<slopetime ‘val1',’val2'” for further information.
The two ramp profile shapes has both its benefit and draw backs. The cosines shape is smooth all
the way but has a higher dI/dt in the middle and results in a sinus output voltage shape on an
inductive load whereas the square shape in a trapezoidal output voltage
The ramp profile consist of 80 points with HW interpolated points in-between. Each of the 80 points
has a distance of 1.25ms. In-between. Profiles with shorter distances than 100ms (80*1.25ms) are
achieved by omitting points. Eg. a ramp time of 10ms will only consist of 8 points thereby resulting
in a more course profile.
The figures below shows the shape of the two ramp profiles.
The time slot must be given as a multiple of 1.25ms. Between 1.25ms to 1 second. Any value in-
between will automatically be rounded according to formulae:
{time slot}=frac({time}/0.00125)*0.00125
The ramp profile can be stopped eithe with a “STOP” command or when the power supply is turned
OFF. The state of the ramp profile can be read through the “RR” command.
Quadratic ramp shape
Cosines ramp shape
DANFYSIK A/S - DK 2630 TAASTRUP - DENMARK.
DOC NO P80303Sk