Automated Controller Design - Parker Compax3 Series Operating Instructions Manual

Parker EME
Please observe:
Correlation between the terms introduced
The introduced terms:
stability
Attenuation
velocity
bandwidth
setpoint and disturbance behavior
Control variable limitation
Replacement time constant
Stiffness
are related as follows:
A well-attenuated control features a stable control behavior.
The velocity of a control loop is a measure for the reaction rate of the controller to
the disturbance variable (disturbance behavior) as well as to the setpoint variable
(setpoint behavior).
The faster the control, the higher its bandwidth.
The term replacement time constant is an approximation and is only valid in a
defined scope1. In this scope, the control is always stable and well-attenuated.
If the controller does not work in the linear range, but the control variable of the
controller is within the limitation, the control slows down and the control difference
rises.
The stiffness represents the bandwidth of the velocity control. The higher the
stiffness value of the velocity control, the higher the bandwidth of the velocity con-
troller and the stiffer the drive.

Automated controller design

In this chapter you can read about:
Jerk response of the velocity loop depending on the optimization paramter "attenuation" and "stiffness"
......................................................................................................................................... 202
D-term .............................................................................................................................. 202
Postition loop ................................................................................................................... 202
The controller design takes place after the configuration immediately before the
configuration download into the device. The controller coefficients are preassigned
according to the design method of cross-ratios so that a stable control is achieved.
The automatic, robust controller design calculates the P and I terms of the indivi-
dual controllers (current, velocity, position) on the basis of the configured motor
and application parameters.
Faulty motor and application parameters may lead under certain circumstances to
instable controllers.
The controller parameters are not directly available for the optimization. Instead,
they can be changed with the aid of the following optimization parameters:
Optimization of the current controller dy-
namics:
Optimization of the velocity loop dyna-
mics:
The bandwidth parameter states the actually effective % of the calculated default
velocity. The default bandwidth of the controller is fixed to approx. fGR=531Hz. In
reverse this signifies that each motor delivers the same jerk response. The prere-
quisite is, of course, that you keep out of the control signal limitation (voltage limita-
tion). The attenuation characterizes the controller's tendency to oscillate with re-
spect to an excitation signal (see below). The stiffness (of the velocity loop, corre-
192-120114 N5 C3I22T11 June 2008
Setting up Compax3
Current loop bandwidth in %
"Attenuation of current loop" in %
"Stiffness" in %
"Attenuation" in %
Velocity loop - "D" term in %
201