PLECS (Piecewise Linear Electrical Circuit Simulation) is a software tool for system-level simulations of electrical circuits developed by Plexim. It is especially designed for power electronics but can be used for any electrical network. PLECS includes the possibility to model controls and different physical domains (thermal, magnetic and mechanical) besides the electrical system.

Most circuit simulation programs model switches as highly nonlinear elements. Due to steep voltage and current transient, the simulation becomes slow when switches are commutated. In most simplistic applications, switches are modelled as variable resistors that alternate between a very small and a very large resistance. In other cases, they are represented by a sophisticated semiconductor model.

When simulating complex power electronic systems, however, the processes during switching are of little interest. In these situations it is more appropriate to use ideal switches that toggle instantaneously between a closed and an open circuit. This approach, which is implemented in PLECS, has two major advantages: Firstly, it yields systems that are piecewise-linear across switching instants, thus resolving the otherwise difficult problem of simulating the non-linear discontinuity that occurs in the equivalent-circuit at the switching instant. Secondly, to handle discontinuities at the switching instants, only two integration steps are required (one for before the instant, and one after). Both of these advantages speed up the simulation considerably, without sacrificing accuracy. Thus the software is ideally suited for modelling and simulation of complex drive systems and modular multilevel converters, for example.

In recent years, PLECS has been extended to also support model-based development of controls with automatic code generation. In addition to software, the PLECS product family includes real-time simulation hardware for both hardware-in-the-loop (HIL) testing and rapid control prototyping.

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