Designing Low-Power Flyback Inductors Using Tiny Toroids (Part 2): Calculating Losses
by Dennis Feucht, Innovatia Laboratories, Cayo, Belize, How2Power Today, Jul 15 2019
Focus:
Part 1 of this article described the design of a low-power flyback converter inductor using
three stacked T20-26 cores. This part 2 presents further details of the inductor design,
specifically the additional design formula required for determining the winding turn length of
the unibundle-constructed six-strand winding previously specified. This part also explains how
to determine winding resistance and both core and winding power loss. Using this loss
information, the effect of the inductor on converter efficiency, based on ideal output power,
can be found. Does this design approximately balance core and winding losses to achieve optimum
efficiency? If not, which loss dominates and why? The factors at play are explained and some
conclusions are drawn about the usefulness of small cores in low-power converter designs.
What you’ll learn:
- How to determine the core and winding losses for a toroidal inductor with unibundle winding
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