Design and Modeling of Anti Wind Up PID Controllers - Complex System Modelling and Control Through Intelligent Soft Computations - page 38

Fig. 27 DC motor torque

With the results obtained in this section, it is proved that a PID anti windup
controller by SOF and H ∞ SOF can be derived for the control of MIMO systems
when the inputs are saturated or constrained. In the following section a discussion
of all the proposed anti windup controllers derived in this chapter are shown in
order to analyze the advantages and disadvantages of these control techniques.

7 Discussion

In this chapter four anti windup controllers for SISO and MIMO continuous and
discrete time systems are shown. For the

first two cases, the anti windup controllers
derived in the respective sections, it is shown that when the plant system is rep-
resented by a first order plus time delay model, the PID anti windup internal model

controller techniques can be achieved meeting the internal stability and robustness
requirements. A back calculation

filter was implemented in order to suppress the
integrator action when the input of the system is saturated, this compensation
strategy reduces the increasing of the integrator output when the system saturates
while ensuring the system stability.
It is proved that the advantages of the anti windup SISO continuous time systems
is that they reduce the unwanted effects produced by windup, obtaining better
results such as small overshoot and small settling time. It is proved that when a PID
controller is implemented with no anti windup back calculation the performance of
the system deteriorates due to the windup phenomena.
In the case of the discrete time SISO systems, a similar approach such as the
SISO continuous time system where a back calculation filter is implemented to

improve and avoid the deterioration of the system performance. The advantages of
this control strategies is that the overshoot, settling time and other characteristics of