Setting
up Compax3
C3I20T11 / C3I32T11
174
192-120103 N13 C3I20T11 / C3I32T11 December 2010
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
controller, the saturation at higher currents will result in too fast current control.
This behavior can be counter steered with saturation values (entered in the "motor
characteristics" 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
(see on page
233, see on page 233, see on page 234).
Quality of different feedback systems
In this chapter you can read about:
Interface ........................................................................................................................ 174
Resolution ..................................................................................................................... 175
Noise ............................................................................................................................. 175
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
respect 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 drive and
feedback. Analog sine/cosine signals or digital encoder signals (RS422 standard)
are used to transmit the incremental position information. Due to the high
interpolation rate (approx. 14 bits) of the Compax3 servo controller, an analog
sine/cosine signal is in most cases preferable to digital encoder signals.
