Modelling and control of two-phase systems

This paper outlines a linear model-based control design procedure, suitable for processes involving two-phase phenomena, where the transient response is often subject to nonminimum phase characteristics: inverse response and time delays. We show that in order to capture these features in the process models implicit in the control scheme, it may be necessary to model the transients in each phase separately, thus precluding simple homogeneous approaches. Furthermore, as shown by two examples, combinations of nonminimum phase characteristics can be accurately modelled by the Parallel Linear Structure, introduced here, which can be the basis for improved linear control design.