Transient Eddy Current Distribution In the Shield of the Passively Compensated, Compensated Pulsed Alternator: Iron-Core Machines

A model describing the transient eddy current distribution in the shield of a passively compensated compulsator is derived. An analytical solution of the two-dimensional convective diffusion equation is obtained. In obtaining the solution, a response to a step excitation is solved. This is convolved with specific time functions corresponding to the nature of the excitation current. The responses to step excitation, with and without relative motion of the shield, are computed and the step response is used to calculate the response to a sinusoidal excitation. This solution is used to interpret various experimental observations obtained from test data on the compulsator and also for preparing design data for passive compulsators with iron cores. The disparity between the model and the experimental observations is due to the limitations in representing the boundary conditions at the shield-rotor iron interface. However, the model could be used to calculated the relative merits of different shield designs and materials. In a design where the shield-rotor interface is indeed either permeable or highly conductive, the model would serve very well