Discrete PID
Discrete parallel or recurrent model of PID controller.
Library
GFLIB
Description
Performs a discrete-time PID controller. For a paraller PID controller, the transfer function takes form:
where a(z) represents integration method.
For a recurrent PID controller, the transfer function takes form:
Parameters and dialog box
The PID pane of the Discrete PID block dialog box appears as follows:
By selecting Parallel structure 5 types of PID controller are available (PID, PI, PD, P and I). For PID, PI, PD and I type there is a user-defined Integration method (see Discrete integrator for more information). Proportional, Integral and Derivative gain are user-defined as well as Filter coefficient and Sample time.
By selecting Recurrent structure a recurrent model with its cc1, cc2 and cc3 parameters is available.
The Limits pane of the Discrete PID block dialog box appears as follows:
The pane is available only for Parallel controller structure. At this pane it's possible to turn on the output saturation with desired limits. In addition there is an optional anti wind-up if the controller contains an integration part.
Inputs and outputs
Inputs:
err - input error signal
Outputs:
out - output control signal
Integ - output from integration part
LimitFlag - indicates saturation (1 = limited, 0 = not limited)
See also
Continuous PID, On/Off controller,