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Motors that are designed for high-speed operation at several times base speed will tend to have lower impedance.
It may then
be necessary to reduce the current loop gain.
In this case it is necessary to go into the 'test functions' menu.
This is found under 'system/reserved'.
Select test function 2.
This will cause the software to generate a square wave current demand.
The amplitude, period, and offset may be set by the
parameters 'current amplitude', 'current period', and 'current offset' respectively.
It is convenient best to set these numbers to
200, 40, and zero respectively.
Return to the 'current loop' menu under 'set-up parameters'. Select 'gain'.
This is a number which may vary between 0 and
255.
This number will typically be around 70 for most motors, but for higher speed motors it may need to be increased.
Note
that to increase the gain, the number in 'GAIN' needs to be decreased.
Turn on the drive and observe the actual current with an oscilloscope on the diagnostic test pin.
See diagram 9.1 for the
location of the two current feedback signals.
If the current loop gain is correct, or too low, the current feedback should follow the square wave current demand in a
smooth controlled manner with no overshoot.
When it has reached the new level it should settle down to a smooth waveform
with a small amount of ripple.
As the gain is increased (i.e. the number in 'gain' is decreased) the current will follow the demand with less delay.
As the
gain is increased further (i.e. the number in 'gain' is decreased further) the point will be reached where the ripple (in the
steady state when it has reached its new level) will suddenly increase.
When this happens, the gain should be reduced until
the ripple drops back to the low level.
The aim is to get the current to follow the demand with minimum delay, while ensuring the steady state ripple remains at a
minimum.
This manual was downloaded on www.sdsdrives.com
+44 (0)117 938 1800 - [email protected]