IEEE Power Electronics Magazine - September 2021 - 97

White Hot
(continued from page 100)
see this column until the magazine is
published. I also want to say that
I have no financial interest in any of
these companies. I do have a commercial
license to SIMPLIS but not to
the SIMPLIS Magnetics Design Module.
I have discussed a collaboration
with Frenetic that would give me
access to their platform in return for
creating promotional materials but to
date I have done no work for Frenetic
and have not benefited from their tool.
Ridleyworks, from Ridley Engineering,
is more than just a magnetics
design and analysis package. It is
a full power supply (well, dc-dc converter)
design tool. The user enters
the specification and switching frequency
and chooses one of nine
topologies. The software does all the
basic design calculations and circuit
simulations. It is very interesting that
Ridleyworks is implemented entirely
in Excel.
For the magnetics, the calculations
are much more than just inductance
and turns ratio. Ridleyworks
has a good sized library of core
shapes and core materials. The user
can review the program's selections
and make their own choice of core
shape, core material, and windings.
The program allows the user to enter
custom core shapes.
The program makes estimates of
the core and winding losses based on
the converter operating conditions. A
special feature is the modeling of
winding and core losses. Ray Ridley
has long preached the importance of
considering proximity loss in magnetics.
Many designers skip this even
though the proximity effect can
greatly multiply winding losses. To
model ac resistance and proximity
loss the winding is modeled as a dc
resistance in series with a number of
paralleled resistors and inductors. At
dc the only resistance is the dc resistance
as all the other resistors are
shorted by the inductors in parallel.
As the frequency increases, so does
the impedance of the inductors. This
shunts current from the inductors to
the resistors in parallel and raises the
resistance. The results are an astonishingly
good match to the measured
ac resistance as a function of frequency.
A similar approach is used to
model core losses.
While this modeling by itself is
impressive what makes this really
valuable is the one-click export of the
converter circuit with the magnetic
models to either LTspice or PSIM. For
LTspice, the program can generate
either models with Vorperian's average
switch model for control loop
analysis or transient models for
examining switching waveforms. All
in all while Ridleyworks is a good
tool for getting a design quickly, the
advanced magnetics modeling really
distinguished Ridleyworks from
other basic design programs.
SIMPLIS, from SIMPLIS Technologies
is a simulator developed especially
for switch mode circuits. SIMPLIS
now has an add-on Magnetics Design
Module (MDM) based on work done
at ETH Zurich. After adding an inductor
or transformer to a SIMPLIS simulation
schematic the user can select
the simulation level. Selecting a Level 3
model allows the user to enter the
details of the device's design: core
shape, core material, air gap details
(number, gap length, placement), and
very detailed winding information.
For the core materials, SIMPLIS has
additional core loss data based on triangular
excitation for several popular
core materials allowing for a more
accurate loss calculation. With this
information the SIMPLIS MDM calculates
a detailed simulation model and
updates the simulation schematic.
Simulations use this detailed model
to calculate the circuit performance.
This can show, for example, in a simulation
of loop gain where losses in an
output inductor add to the damping.
After the simulation is run SIMPLIS
then post processes the simulation
data and shows the details of the
losses in the magnetics device. The
result is essentially a finite element
analysis of the magnetic device. For
example, an inductor with a significant
ac current will show much higher
losses in the windings near the gap
due to the effects of the fringing flux
from the gap. With this information
the design can quickly experiment
with the design of magnetic device
including core materials, gap size and
placement, and details of the winding
structure to optimize how the magnetic
device will work in circuit. For
those that already use SIMPLIS, the
MDM module, although it is an additional
cost, allows the designer to
rapidly refine and optimize the magnetics
design.
The most advanced magnetics
design tool that I know is the webbased
Frenetic from Spain. Frenetic,
founded by graduates from the Polytechnic
University of Madrid, is working
to apply the latest artificial intelligence
(AI) tools to the design of magnetics
devices. Their platform is
evolving rapidly but is already very
impressive in its capabilities. The
user starts by entering the type of
magnetic device, e.g. inductor, transformer,
or flyback inductor, and associated
circuit specifications. The tool
then does some quick calculations
and displays a basic simulation of the
currents in the device. It then goes on
to choose a core shape, core material,
and design the windings. It calculates
the winding dc and ac resistances,
plots the ac resistance versus frequency
including proximity effects,
and the losses in the windings and
cores. It then displays a diagram of
the windings and insulation layers.
The user can then review the
design and explore alternatives. For
example, the user can select another
core shape and material and the platform
recalculates everything. Or the
user can change the type and size of
the wire, e.g. changing from solid
round wire to Litz wire. This recalculation
is very fast allowing the user to
explore a wide range of design options
and variations to find the solution best
for their application. I will say that
in my time experimenting with the
September 2021 z IEEE POWER ELECTRONICS MAGAZINE 97
IEEE Power Electronics Magazine - September 2021

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - September 2021
