IEEE Power Electronics Magazine - September 2020 - 92

White Hot

by Robert V. White

Packaging and Integration and
the Future of Power Electronics

n power electronics we often ask
which drives power electronics
forward: devices or topologies.
My answer is that I believe devices
have driven the advancement of
power electronics more than topologies. Electronic control of electric
power started more than a century
ago with mercury arc rectifiers
and magnetic amplifiers. To me it
was the invention of the silicon controlled rectifier (SCR) in 1957 that
ushered the modern era of power
electronics. Thereafter, the control of electric power with solidstate devices continued to advance
with the introduction of the bipolar
power transistors in the 1960s, followed by the power MOSFET in
the late 1970s, and the IGBT in the
mid 1980s.
The pace of development in topologies has been much more limited.
Resonant conver ters, especially
zero-current-switching (ZCS), were
developed to take advantage of
SCRs. The basic pulse-width-modulated (PWM) converters have been
known for some time. In the 1985
book "Modern DC-To-DC Switchmode Power Converter Circuits"
Rudy Severns showed the common
dc-dc converter topologies and the
derived several extensions. In the
mid-1980s, various ZCS and zero-voltage-switching (ZVS) quasi-resonant
Digital Object Identifier 10.1109/MPEL.2020.3011306
Date of current version: 15 September 2020

IEEE POWER ELECTRONICS MAGAZINE

converters (QRC) were introduced
but these have failed to gain wide
spread use. Soft switching converters, such as the phase-shifted fullbridge (PSFB) appeared a bit later.
These topologies have been more
widely used as they do give an advantage in efficiency. Still, looking at
these quasi-resonant and soft-switching topologies, I can see their roots in
the various resonant circuits used
with SCRs thirty years ago.
In his 1989 Ph.D. thesis, "Synthesis
of PWM and Quasi-Resonant DC-toDC Power Converters" Dragan Maksimovic´ systematically derived pretty
much all possible PWM converters.
Since then the development of multilevel converters has advanced power
electronics in some higher power
applications. The Vienna Rectifier,
invented by Johan Kolar in 1994, is
one of the more well know multilevel converters.
While we might see some evolutionary progress due to new topologies, I am very skeptical that we will
see any significant improvement.
After all, with all of the various topologies we have available the buck and
flyback are still the two most commonly used.
In recent years, there have been
significant advancements in power
electronics (i.e. improved efficiency
and greater power conversion density) that have been driven by the introduction of wide bandgap power
devices. Both gallium nitride (GaN)

z September 2020

and silicon carbide (SiC) have made
possible some important leaps in
efficiency and power conversion
density. However, this is an advancement in materials as the basic devices are still previously known transistor structures.
To this list of devices, topologies, and materials that advance
power electronics I would like to
add integration. When I was looking into GaN devices that integrate
the driver with the switch that I
started thinking about the importance of integration across all of
power electronics.
Integration is a broad term. It covers everything from system level
assemblies (think pre-made IGBT
stacks) to systems-in-packages
(think of the tiny dc-dc converter
modules that are widely available) to
multi-chip modules (think of the
countless IGBT modules in all kinds
of configurations) to die-level integration. It is my opinion that in the
coming years integration will be as
important to the advancement of
power electronics as any improvements or inventions in devices, topologies, or materials.
For high power applications integration is widely used. The power
electronic building block (PEBB) concept has become off-the-shelf as semblies of IGBTs, drivers, and heat
sinks. Some come with inductors or
(continued on page 87)

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