IEEE Power Electronics Magazine - September 2021 - 68

+In
Primary
Bridge
Transformer
1:K
Synchronous
Rectifier
+Out
NBM6123
6.4 kW at 99% Efficiency
10 kW/in3
SAC
Control
(a)
(b)
FIG 2 The NBM6123, a bidirectional 800-to-400V fixed-ratio converter uses a non-isolated version of the SAC topology and Si MOSFETs
to achieve a power density of 10 kW/in3 at 99% efficiency.
converter designs, but at Vicor the
modular power approach to power
systems design and unique proprietary
architectures, topologies, control
systems and power packaging give
longevity to the Si MOSFET. Vicor has
been converting and regulating higher
voltages at higher frequencies for over
40 years, with constant innovations
that advance power density and efficiency.
In the early 1980s, Patrizio
Vinciarelli, founder and CEO of Vicor
and the 2019 recipient of the IEEE
Willian E. Newell Power Electronics
Award, recognizing his outstanding
contribution to power electronics,
developed a new topology the quasiresonant
forward converter with
active clamp. This topology switched
up to 1 MHz using a frequency-modulation-based
control system with
zero-current switching (ZCS) and the
Brick was born (Figure 1).
So, having moved to the dark side
(sales and marketing) and not remembering
all of my engineering training,
I asked senior applications engineer
Tom Curatolo, who has been with
Vicor for over 30 years, to explain some
of the Brick topology and control system
benefits. This is what he told me.
The Brick used Si MOSFETs and
Power electronics
for any system.
took full advantage of high-frequency
switching plus the capability of synchronizing
the main switch transition
at zero current with a fixed on-time,
significantly reducing switching losses.
Alternative hard-switching topoloComponents
& Assemblies
Standard & Custom Designs
90 - 1000A @ up to 1800V
Discrete Diode and SCR modules
in single and dual packages
16 - 300A @ up to 1800V
Discrete Stud Diodes and SCR in
standard Jedec packages and
standard or reverse biasing packages.
Also available in fast recovery
Contact DTI today to discuss
your power electronics design.
+1.972.248.7691 II www.deantechnology.com
gies trade off higher switching
frequencies with system power losses.
Achieving high efficiency also
requires synchronous rectification
and incorporating multiphase functionality.
Lower frequency switching
leads to larger passive components,
which are required to hold the power
for a longer time period between the
MOSFET's longer switching cycles
based on the variable on-time.
Another tradeoff is that lower
switching frequencies with chopping
current during main switch transitions,
results in high harmonic distortion
and output ripple which needs to
be filtered. This typically means adding
larger input filters, which increases
size and weight.
Thank you Tom! As a result of these
tradeoffs, power systems based on

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IEEE Power Electronics Magazine - September 2021

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