An efficient field-circuit coupling method by a dynamic lumped parameter reduction of the FE model

Abstract

A field-circuit coupling method is presented, whose basic idea is to extract from the FE model, on basis of energy balance considerations, a temporary lumped parameter representation of the electrical machines, to be used in the circuit simulator model of the power electronic supply. The dynamic coupled model of the complete drive obtained this way can be iterated over a limited period of time, with a time step adapted to the high frequency of electronic commutations. When the temporary representation of the machine has come, or is expected to have come under a given accuracy threshold, a new FE simulation is performed in order to generate an updated set of lumped parameters, and the process is repeated. This method allows decoupling the time constants of the field problem from that of the circuit problem, which is typically one or two orders of magnitude smaller. This yields a considerable saving of computation time with a controllable, at least a posteriori, loss of accuracy. The method presented in this paper is also characterized by the fact that only known quantities of the nonlinear FE method are used in the identification process, which can therefore be done systematically and in an automated way.