structure
Keypad and
format
Advanced
parameter
descriptions
Serial comms
The speed ripple can be quite high, for example with a 4096 line encoder the speed ripple is 14.6 rpm, but this does not define the resolution of the
speed feedback which is normally much better and depends on the length of the measuring period used to obtain the feedback. This is shown in the
improved resolution of the value accessible in Pr
3.02
{
di05,
0.40
} which is measured over 16 ms, i.e. a resolution of 0.23 rpm with a 4096 line
encoder. The speed controller itself accumulates all pulses from the encoder, and so the speed controller resolution is not limited by the feedback, but
by the resolution of the speed reference.
If a SINCOS encoder is used from an option, the encoder speed ripple is reduced by a factor of 2(
2-Interpolation
bits
).
For example, with the nominal 10 bits of interpolation information, the speed ripple is reduced by a factor of 256. This shows how a SINCOS encoder
can reduce noise caused by encoder quantization without any filtering in the speed feedback or the current demand, so that high gains may be used
to give high dynamic performance and a very stiff system.
speed controller feedback branch.
motor flux if field weakening is active, and then used as the torque producing current reference.
otherwise the flag is 0.
44
Mentor MP Advanced User Guide
www.onxcontrol.com
Issue Number: 4
3.05
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