IEEE Power Electronics Magazine - June 2018 - 19

Passive Components

by Tom Keim

aPEc Investigates Developments
in High-Frequency Magnetics

or the past several years, the
Power Sources Manufacturers
Association (PSMA) and the
IEEE Power Electronics Society
(PELS) have collaborated to sponsor
a collocated pre-Applied Power Electronics Conference and Exposition
(APEC) event, which constitutes a
day-long discussion of magnetic
components for power electronics
systems. This series of events evidently fills an ongoing need, as attendance has been robust.

A Few Words on
Documenting Core Loss
Industry Session IS02 was largely a
short version of the day-long workshop, featuring many of the same
speakers and the same subjects. The
session opened with a talk by Prof.
Charles R. Sullivan of Dartmouth University, Hanover, New Hampshire. He
stated at the outset that his objective
was to summarize the entire day into
one 25-min presentation. The focus of
the talk was on core loss, although
there was information about the
effect of winding choices on loss as
well. There was apparently some dissatisfaction expressed at the workshop with the degree of the core manufacturer's documentation of core
losses. In a factual and nonjudgmental way, Prof. Sullivan made it evident
how difficult it might be to provide all
Digital Object Identifier 10.1109/MPEL.2018.2821783
Date of publication: 14 June 2018

of the information that each customer
ductors can be so low that the magnetmight want. He pointed out that loss
ic components are now the biggest
is nonlinearly related to flux amplicontributor to losses in the entire contude and frequency and core temperaverter, which suggests that comproture. In some cases at least, there are
mising other components of the device
dependences upon
to make the magnetcore dimensions (i.e.,
ic component better
even with the effect
may be a proper
The focus of Prof.
of flux amplitude
design choice. This
Sullivan's talk was on
and frequency and
realization may excore loss, although
core temperature
plain the wide poputhere was information
dealt with, the loss
larity of this formerly
about the effect of
per unit volume is
exotic subspecialty
winding choices on
not constant among
of power electronics.
cores of different
It may also explain
loss as well.
dimension). It did
why this session
not take a genius to
occurred in an overfigure out that the successful design
filled conference room, despite havof a magnetic element is quite likely
ing been assigned one of the largest
to be an iterative process. The referrooms available.
ences that Sullivan provided are also
of great use.
Some Complexity in the Design

of Windings for Magnetic
Components

A New Perspective on the
Importance of Magnetic
Components
The next speaker was Ionel Jitaru of
Rompower Energy Systems, Inc. His
speech was titled "GaN Technology as
an Enabler for Higher-Efficiency Magnetics." Like the first speaker, Jitaru
spoke simply and directly. His visual
aids strongly supported his statements;
however, his numbers suggested a different take on the interaction between
wide-bandgap semiconductors and
magnetic components. Additionally,
his presentation indicated that the
switching losses in the new semiconJune 2018

Weyman Lundquist of West Coast
Magnetics was the third presenter. His
presentation, "Foil Windings for SMPS
Inductors and Transformers," was
more like a case study of the process
of design for an inductor for a specific
application. The author amply ex plained the tradeoff between conventional magnet wire, litz wire, and copper foil as winding materials and
described that the process of selecting
a design for production involved the
construction and testing of a number
of different prototypes. The speaker
clearly knows and uses the work of
z IEEE PowEr ElEctronIcs MagazInE

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - June 2018