Extended Thévenin equivalent circuits

The authors propose a method to obtain an equivalent circuit for a network portion that is accessible by more than two terminals. This method can be seen as an extension of Thevenin´s theorem (and of its dual, Norton´s theorem), whose application is limited to two-terminals networks. In the analysis of electrical circuits the extended Thevenin method (ETM) can be used in all cases in which the circuit solution is needed only in a limited part of the network. For instance, when variations of circuit parameters occur only in limited portions of the network, a parametric analysis can be performed in a faster way connecting these portions to a reduced equivalent of the remaining network. In so doing, the computation global time can be reduced. Optimisation is the typical application in which a huge number of circuit solutions have to be calculated, differing one from the other by the value of some parameters. To validate the method, and to show its potential, an axial flux disc machine (AFPM) has been modelled by means of an electrical circuit and the latter has been solved by means of the proposed method.