Time-varying resistors, capacitors, and inductors in nonlinear transient finite element models

Finite element analysis of saturable lossy magnetic components is extended to include the effects of time-varying circuit elements. Resistors, capacitors and inductors are varied in time using coupled nonlinear transient electromagnetic and structural finite elements. Examples show how changing the size of certain finite elements produces the desired time variations of R, C and L, and that the resulting voltages are accurately computed. Also, a time-varying capacitor is placed on the secondary of a saturating transformer with eddy currents in its core, and the computed secondary voltage is shown to be highly dependent on both the time variation and the core conductivity.