Defining hybrid hierarchical models in πHYFLOW

This paper presents πHyFlow, a modular approach to the process interaction worldview (PI). Traditionally, PI supports a set of interacting processes without enabling modular and hierarchical model definition. πHyFlow basic models define a dynamic set of processes while also enabling a modular interface for supporting model composition. πHyFlow allows an exact representation of continuous signals based on the concepts of dense outputs, and generalized sampling. πHyFlow ability to support accurate models of hybrid systems is presented through a DC-DC converter (DCC) based on a resistor–capacitor (RC) electrical circuit. The DCC output voltage can be modeled by a first-order differential equation that is solved using an exponential time differencing (ETD) integrator. The DCC network model uses a digital on-off controller and an ETD. Simulation results are generated by πHyFlow++, a C++ implementation of the formalism.