Computation of inductances for pulsed power generators using a semianalytic method

Pulsed power generators being developed for applications in electromagnetic launch operate at high speeds and are intended to deliver megajoules of energy within a few milliseconds. The self-inductances of the rotor and the stator, L/sub r/, L/sub s/, and the mutual inductance, M(/spl theta/), are required to model the performance of these machines. In general, three-dimensional (3-D) field computations are required for the calculation of inductances, and the integration of the stored energy has to be carried out over an infinite domain. The domain of integration could be reduced to just the volumes of current-carrying conductors, using equivalent expressions for the total energy involving the dot product of the current density and the magnetic vector potential. A semianalytic code, Faraday, has been developed using this method for the computation of L/sub r/, L/sub s/, and M(/spl theta/). The 3-D topology of conductors with rectangular cross sections in the rotor and the stator is described by a set of discrete rectangular segments (parallelepipeds) with specified current directions. The segments are continuous along the axis. Analytic integral expressions for the total energy of differential current-carrying segments are used to calculate the total energies and inductances. The inductances L/sub r/, L/sub s/, and M(/spl theta/) for a model pulsed disk alternator were computed using Faraday. The results compare favorably with experimental data.