[A mathematical representation of converters. I]

The authors discuss mathematical models of the voltage and current parameters U/sub k/, I/sub k/ at a nodal point in a branch of an electrical circuit of a type found in voltage converters, incorporating GTO thyristors. The electrical factors have resistive and inductive components which vary in time. A ladder function H(I/sub k /) is formulated, which enables the currents at the point to be defined as a sequence. This is generalised with the help of operators-alpha, beta, gamma, etc., and constitutes a polyphase non-linear system. An asymptotic technique is introduced which permits the polyphase system to be contracted to a simple final system, leading to a simulation model.