Switching Power Supplies A - Z, 2nd Edition

Chapter 5

Advanced Magnetics

Optimal Core Selection

This chapter is a recap of the basics, progressing on to advanced magnetics. It starts by explaining the grass-root differences in the underlying energy transfer process between the three fundamental topologies. It shows how the size of their inductors varies for a given output power based on duty cycle and topology. The concept of magnetic circuits with the distribution of the B and H fields in gapped and ungapped cores is introduced along with derivations of the equations for energy storage capability. The innovative “air gap factor” is introduced, which greatly simplifies and aids a typical power conversion engineer’s understanding of gapped magnetic cores. The morphing of E-cores into toroids ...