Analysis on the behavior of magnetic field for an amorphous choke core in PFC circuit

摘要

A computer simulation was carried out toinvestigate the behavior of magnetic field and eddy currentproperties using FLUX2D on an amorphous choke core.Magnetostatics analysis shows that a flux was gradually increasedwith forward to inner edge.(No.4->No.1O) This is due to thedecrease of magnetic path length with forward to inner edge. Theexistence of gap in magnetic path caused the flux to scatter outsidethe core. A flux density was lowered inside the core and relativelyhigh on both sides of edge. Two types of the flux density behaviorwere detected at the gap and 5 mm above and below from the gapcenter position, where it had a similar pattern inside the core andextremely different tendency on both sides of edge.Magnetodynamics analysis at the frequency of 30 kHz revealedthat eddy currents were concentrated on both sides of edge andnear the gap, but almost cancelled out inside the core. The fluxdensity induced by the eddy currents showed almost a similarbehavior. This can be interpreted that the eddy currents formed ateach shell inside the core were cancelled out each other, whilethose on both sides of edge and near the gap remain alive.