IEEE Power Electronics Magazine - June 2019 - 53

keynoter displayed Amber's first commercial 4-h discharge
flywheel storage system that provides 32 kWh of power for
up to 4-h duration. In addition, the keynoter revealed multiple projects underway across the world that accounted for
75,000 h of run time. In summary, key benefits offered by
flywheel energy storage include:
1) flexible capacity
2) ancillary services
3) energy arbitrage
4) renewable integration
5) transmission and distribution upgrade deferral
6) microgrid.
Whether it is urban transit energy wasted because of
traffic or zero-emission transportation, electric traction
is recognized as the future of mobility. The next presentation, "Power Electronics: Enabling Zero Emission Powertrains and Fuel Cell Engines," by Abas Goodarzi, president and CEO of US Hybrid Corporation, gave a review of
fuel cell engines enabling zero-emission transportation. He
explained that a fuel cell is a combustion-less/static engine
that generates electric power directly by extracting the
electrons from hydrogen to power the future transportation. His talk described that power electronics is directly
involved in both power generation and propulsion of the
vehicles. He added, "Power electronics utilizing SiC devices
are integrated with the fuel cell engine to provide the highest power density and more than triple the overall efficiency (fuel in, electric power out) with zero tail pipe emission enabling global GHG [greenhouse gas] reduction and
carbon-free economy." Emphasizing the need for fuel cellpowered vehicles, he concluded that hydrogen generated by
fuel cells is safe and does not generate any harmful fumes."
The last topic of the session was "Power Electronics
for the Space Exploration Hype" by Fernando GomezCarpintero, head of power engineering, Airbus Spacecraft
Electronics. He showed that there is a new drive for space
exploration with a clear need for higher power and higher
efficiencies to drive the electrical propulsion systems. The
answer from Airbus Spacecraft includes the use of new
technologies such as GaN, the implementation of digital
control for smart power management, the use of commercial-off-the-shelf electrical and electronic engineering components, and the digitalization & automation of the development process, stated the keynoter.

Innovative Products
Following the plenary session, the exhibit hall was open,
with vendors displaying both old and new products. Vendors boasting innovative products included Pre-Switch,
Silanna Semiconductor, and Power Integrations, to name a
few. Silicon Valley start-up Pre-Switch Inc., emerging from
stealth mode last year, unveiled AI-based soft-switching
technology for power conversion applications. In essence,
the start-up has developed an AI-based controller chip
called Pre-Flex, which effectively eliminates transistor
switching losses in hard-switched architectures for any

power converter topology. According to the developer, PreFlex technology learns and adapts in-system, on a cycle-bycycle basis, to reliably force resonant soft-switch across
changing loads, input voltages, temperatures, and manufacturing tolerances. As a result, the manufacturer claims that
the technology can offer efficiencies greater than those of
five-level topologies at a fraction of the cost and complexity.
In addition, it also significantly lowers electromagnetic
interference and dramatically decreases dV/dt for any
switch type. Thus, claims Pre-Switch, Pre-Flex can enable
SiC-like performance for low-cost IGBTs and can allow SiCand GaN-based topologies to switch up to 20 times faster
than they do today. "Built into the architecture are innovative cycle-by-cycle safety features and communications that
were never possible before," said Pre-Switch CEO Bruce
T. Renouard.
Combining the Pre-Flex chip with a Resonant Power
Gate driver board, Pre-Switch has readied a new three-phase
gate driver board called Pre-Drive 3 (Figure 2) that promises
to boost switching speed by 20 times and increase EV range by
5-12%. Renouard added, "EV designers have been among the
first to adopt this exciting technology because it dramatically
reduces iron core losses in electric motors at cruising torques.
The three-phase gate driver board was developed to speed
application development."
Silanna unveiled a fully integrated active clamp flyback
(ACF) controller chip, SZ1101, which integrates four key ACF
building blocks on the same silicon die (Figure 3). These
include an advanced ACF controller and three ultrahighvoltage components: an active clamp driver, an active clamp
FET, and a start-up voltage regulator. This level of integration facilitates designing efficient, high-power-density adapters with low bill-of-material cost to satisfy power-hungry
mobile phones, tablets, notebooks, and video game consoles,
said the maker. According to the company, the SZ1101 delivers over 93% efficiency at 9 V/3 A, with an all-silicon design
and a higher than 15-W/in3 power density at 30 W while using
an industry standard silicon MOSFET main switch.
A version for higher-power ac-dc application was also
introduced. Designated SZ1105, the controller is designed
for 60 W of output power, including USB-PD and Quick
Charge. Like the SZ1101, it comes in a 16-pin small outline
integrated circuit package. For dc-dc applications, the
company unwrapped a proprietary power device and process technology aimed at high-efficiency, hard-switching
dc-dc converters. Labeled ZqFET technology, it is designed
to reduce both switching and conduction losses up to
2 MHz. Utilizing this technology with a proprietary controller and gate driver, Silanna has developed high-frequency
dc-dc synchronous buck converters in an integrated quadflat no-leads package that delivers high power density with
a minimum number of external components.
Driving SiC MOSFETs has not been easy. Without
proper isolation and the use of an external boost stage,
efficiently driving SiC MOSFETs may be challenging.
However, these extras add to the cost and size, including
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IEEE Power Electronics Magazine - June 2019

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