Finite element modeling of a transformer feeding a rectified load: the coupled power electronics and nonlinear magnetic field problem

Abstract

Zedimensional finite elements are used to help directly incorporate models of nonlinear power electronic switching devices into nonlinear transient magnetic finite element analysis. Iko applications are considered: a buck regulator circuit and a transformer feeding a rectified load.

Finite element modeling of power electronic circuits containing switches attached to saturable magnetic components

“…If it stays closed, then we apply no force to the model, and the 1D switch element maintains its length of 1 mm. Figure 5 shows the resulting computed voltage waveform across the resistor, which agrees with the previously published peaked current waveform [4] produced when the steel saturates. Finally, consider the case where the switch on the secondary is closed from t=O to 15 ms, open from t=15 ms to 20 ms, and then closed from then on.…”

“…Figure 4 shows a previously published [4] finite element model of a saturating transformer. Its secondary current was previously computed for an 86 mS2 resistor on its secondary winding, and 10,000 amp-turns of frequency 60 Hz injected in its primary.…”

“…Such finite elements models have been described in papers and books beginning in 1991 [4] - [9], and can include the effects of diodes and other nonlinear circuit devices. The nonlinear devices can act as switches, but must act at times dependent on circuit currents and voltages.…”

“…The right hand side is {FE(t)), the electromagnetic excitation vector [4] -[SI, which may involve circuit excitations of various kinds acting on multiturn windings [7], [8]. Equation (1) is solved at each time step for linear or nonlinear materials.…”

Three-dimensional nonlinear finite element modeling of a voltage source excited transformer feeding a rectifier load

“…One approach consists of adding the external circuit currentr M U a l m o w~ directly into the two-dimensional finite element matrix equation [l]. The other approach consists of modeling the ryrtem with 6-0-and tw+dimmional finite elements [2].…”