Overview

"Magnetics", a term that strikes fear in the heart of the average electronics engineer, along with terms such as feedback loop compensation, and electromagnetic interference. Before you throw up you hands in a nervous sweat, consider this, we all had to go through this before you and survived with a deepened understanding.

Magnetism can also be quite analogous to the flow of water through a pipe. B (flux density) can be seen as the number of water molecules flowing through a crossection of pipe. H (field strength) can be seen as the pressure causing the flow. Hysteresis loss is the amount of work done to reorient the magnetic domains within the core. Saturation is when there are no more magnetic domains remaining to reorient. Eddy current loss is the localized circulating flux disturbed by obstacles such as corners in the core just as water does in streams around rocks.

The terms, units and equations may be unusual. Be careful to not mix the units between the MKS and the CGS systems, or you will have results that will extraordinarily large.

Understanding the operation of the magnetics within a switchmode power supply and their design is fundamental to the design of a switchmode converter. The relationships between current, voltage and power are all controlled by the magnetic elements.

Their operation can sometimes seem counter-intuitive. The design of a transformer or inductor not only involves the electrical design but also its physical design. A poorly designed transformer, for instance...