Exploiting Structural Dynamism in Functional Hybrid Modelling for Simulation of Ideal Diodes

Current main-stream non-casual modelling and simulation languages, like Modelica, are designed and implemented on the assumption that model causality remains fixed during simulation. This simplifies the language design and facilitates the generation of efficient simulation code. In particular, simulation code can be generated once and for all, at compile time. However, for hybrid models, the assumption of fixed causality is very limiting: there are many examples, including simple ones, that cannot be simulated. A half-wave rectifier with an ideal diode and an in-line inductor is one such example. Functional Hybrid Modelling is a new approach to non-causal modelling where models are first-class entities and structural dynamism is supported by switching among model configurations. Fixed causality is thus not assumed. Continuous simulation remains efficient thanks to just-in-time generation of simulation code at structural changes and the use of a standard, industrial-strength solver. Re-generation of code at each structural change of course incurs an overhead, but this is typically modest. In this paper we demonstrate how Functional Hybrid Modelling makes it possible to simulate electrical circuits with ideal diodes in a straightforward manner. We consider both a half-wave rectifier and a significantly more challenging full-wave rectifier.