IEEE Electrification - September 2020 - 9

Power electronics
systems located at
the grid edge are
performing
increasingly
sophisticated energy
management
functions.

grid edge. Wide-bandgap semiconductor
devices facilitate high-frequency operation with smaller footprints, faster
response times, and lower device losses.
It is reasonable to expect that if appropriate system architectures, passive
components, and circuit designs are
optimally combined, high-frequency
power electronics will achieve significant performance improvements over
contemporary designs while offering
unprecedented functions at the grid
edge. The advanced functions and
improved efficiency will justify the
additional cost.
In addition to the needs of the electric
grid, other technologies and markets for high-frequency
power electronics are beginning to emerge. The vision
toward a future smart grid offers top-down motivations for
high-frequency power electronics. Power electronics are
playing increasingly important roles in future energy systems, from supporting the future grid with more than 50%
renewable energy, to powering data centers with millions of
modular servers and microprocessors and managing thousands of battery cells in an EV (Figure 3). Novel architectures
open new challenges and enable application-driven innovation that cannot simply be achieved by increasing the
switching frequency.
From the grid perspective, power converters become
more "ideal" at higher frequencies. The gap between the
switching frequency of the power converter and the 60-Hz
grid frequency makes the inverters and power factor correction (PFC) circuits look more like ideal voltage or current
sources. As noted previously, high-frequency power converters are distributed sensors and actuators located at the
grid edge; they probe the dynamic operating conditions of
the grid and provide the needed response to contribute to
grid stability and power quality. These converters will gradually replace bulky central power plants and ultimately

support the future grid as distributed generators.

Devices and Components

High-frequency wide-bandgap
semiconductor devices are ready to
be adopted by grid-interface power
electronics. The voltage ratings of
gallium nitride (GaN) devices have
reached 650 V or even higher, en--
abling them to be widely used in
ac-dc adapters for consumer electronics, EV chargers, and server
power supplies, where miniaturization is the key. The switching frequency of commercial GaN-based
ac-dc adapter products have exceeded 1 MHz and are
approaching 5 MHz. With their cost rapidly dropping, silicon carbide (SiC) devices are becoming commercially
competitive in the medium voltage market. The switching
frequencies of commercial SiC-based inverter products
are approaching megahertz. The switching frequency of
low-power grid-interface power electronics (e.g., adapters,
onboard chargers, rooftop inverters) is likely to approach
10 MHz in 10 years, and the switching frequency of medium-voltage power grid-interface systems (e.g., PV inverters, fast chargers, and data center uninterrupted power
supply) is likely to exceed 1 MHz in 10 years (Figure 4).
Magnetics components remain bulky and lossy. They
present an even greater bottleneck for high-frequency
power electronics than do semiconductor devices, especially at high power. It is not uncommon for sophisticated,
modern power converter designs to have approximately
half of their volume and power losses arising from inductors and transformers. Although GaN and SiC devices offer
superior performance at higher frequencies, the material
performance and design techniques for magnetics are still
limiting the path toward high-frequency grid-interface
power electronics.

Photovoltaic Modules

Battery Stacks

Server Racks

Figure 3. The battery stacks, PV modules, and server racks all comprise a large number of modular units functioning together at the grid edge.

IEEE Elec trific ation Magazine / S EP T EM BE R 2 0 2 0

IEEE Electrification - September 2020

Table of Contents for the Digital Edition of IEEE Electrification - September 2020