Saturation Values; Quality Of Different Feedback Systems - Parker Compax3 Series Operating Instructions Manual

Setting up Compax3
176

Saturation values

A motor may show a saturation behavior at higher currents due to iron saturation.
This results in the reduction of the winding inductance at higher currents. As the
inductance value of the winding enters directly into the P term of the current con-
troller, the saturation at higher currents will result in too fast current control. This
behavior can be countersteered with saturation values (entered in the "motor cha-
racteristics" wizard window of the MotorManager).
Consideration of the saturation values with the aid of a linear characteristic
line
L 100% Entered value of the nominal inductance
Lmin Minimum winding inductance [% of the nominal inductance].
Value to which the inductance of the winding sinks at Ifinal.
lbeg End of the saturation [% of the nominal inductance].
lfinal Beginning of the saturation [% of the nominal inductance].
For the determination of the saturation values please see chapter 0.

Quality of different feedback systems

In this chapter you can read about:
Interface ........................................................................................................................... 176
Resolution........................................................................................................................ 177
Noise................................................................................................................................ 177
The controller quality depends to a great extent on the signal quality of the position
feedback and its signal acquisition. It is therefore important to select a suitable
measurement system for the individual application.
In the rotary range, a resolver is mostly used for reasons of economics. The single
pole resolver provides one sine/cosine period per revolution. In very demanding
applications, the performance of the resolver is often not satisfactory, so that a
SinCos feedback with a higher resolution must be used. The typical resolution of a
SinCos feedback is 1024 periods/revolution.
Other position feedbacks which are often used in the linear range, differ with re-
spect to the reading principle. High-quality optical position measuring systems offer
the highest resolution and accuracy.
Interface
An additional distinctive feature is the electric interface between servo controller
and feedback. Analog sine/cosine signals or digital encoder signals (RS422 stan-
dard) are used to transmit the incremental position information. Due to the high
interpolation rate (approx. 14 bits) of the Compax3 servo controller, an analog si-
ne/cosine signal is in most cases preferable to digital encoder signals.
192-120114 N5 C3I22T11 June 2008
C3I22T11