IEEE Electrification - June 2021 - 42

1) The first-stage integration for the residential fast charger
is the connection of ac with solar, EV, and battery
storage in dc.
2) The dc charger could become the central energy manager.
In this scenario, individual inverters could phase
out; then solar and battery storage could be connected
directly to the fast charger that is serving as the " energy
broker " among different stages and making the dc
grid controllable, safe, and accessible.
3) When a safe and reliable dc line becomes available
and energy-efficiency standards increase the pressure
on manufacturers to deliver higher efficiency
appliances, appliances with capabilities for direct dc
connection will have a particularly good competitive
advantage. Heat-pump A/C could eliminate the rectification
and PFC stage (the dashed blue block in Figure
6) and the corresponding power loss, reducing the
driver overall losses by half. The availability of residential
dc voltage may also enable the appearance of
ultra-efficient LED lighting since there is no need of
ac-to-dc conversion in LEDs.
4) Migration to dc of the remaining appliances is expected
at this stage, driven by the search for a more efficient
and smart home. The house of the future can be
envisioned with appliances capable of dual ac/dc
connection or single dc connection.
Remaining Challenges
The dc residential power grid will continue to face multiple
challenges: an important and complicated one is
the difficulty of interrupting the dc current. AC power
systems present the great advantage that they are easier
to interrupt because of the natural zero-crossing that
exists in the ac current. Currently, there is no low-cost
and effective dc breaker solution. The residential dc
breaker of the future may have a design change and be
based on a fast semiconductor that opens quickly
enough depending on " di/dt " at a low current, avoiding
the development of a large current above the breaker
capability to open. The bottom line is that dc breakers
based on semiconductors are a good solution, but they
need to significantly reduce their cost to be competitive
and functionally comparable with present ac residential
breakers.
According to Y. Liu et al. (2017), another problem is the
possibility of HF resonance occurring among the converters.
This problem is minimized by assigning one of the
converters as the master controller in the design. Until
now, energy-storage devices have been the preferred manager
(master controller) in power systems for residential
applications. If a distributed residential controller prevails
(there is no master controller), then each dc/dc converter
will need to have a damping control to avoid losing the
stability of the dc system. Other problems that are more
complex in dc than in ac systems include galvanic corrosion
and grounding.
42
IEEE Electrification Magazine / JUNE 2021
Conclusion
The high market growth in the EV sector will create significant
changes, not only in the way transportation
works today but also in propelling a transformation in the
power grid infrastructure. This electric revolution will
impact energy production at all levels-generation, transmission,
and distribution-because of the need for extensive
deployment of dc fast charging. This article explored
and proposed potential scenarios of how dc fast charging
may affect the residential power system, driving it to
become more efficient and more distributed through the
acceptance of dc-based energy systems at home.
For Further Reading
" US EV market sales to rise to 6.9 million units by 2025: Frost &
Sullivan, " S & P Global Platts, London, Nov. 19, 2020. https://
www.spglobal.com/platts/en/market-insights/latest-news/
electric-power/111920-us-ev-market-sales-to-rise-to-69-million
-units-by-2025-frost-amp-sullivan (accessed Mar. 30, 2021).
S. Loveday, " Electric cars with the longest range in 2021 "
U.S. News and World Report, Best Cars Sept. 16, 2020. https://
cars.usnews.com/cars-trucks/electric-cars-with-the-longest
-range (accessed Mar. 30, 2021).
D. Boroyevich, I. Cvetkovic´, D. Dong, R. Burgos, F. Wang and
F. Lee, " Future electronic power distribution systems a contemplative
view, " in Proc. 12th Int. Conf. Optimizat. Electr. Electron.
Equipment, Brasov, Romania, 2010, pp. 1369-1380.
M. Nasir, Z. Jin, H. A. Khan, N. A. Zaffar, J. C. Vasquez and J.
M. Guerrero, " A decentralized control architecture applied to
DC nanogrid clusters for rural electrification in developing
regions, " IEEE Trans. Power Electron., vol. 34, no. 2, pp. 1773-1785,
Feb. 2019. doi: 10.1109/TPEL.2018.2828538.
G. Liu, A. Khodamoradi, P. Mattavelli, T. Caldognetto and P.
Magnone, " Plug and play DC-DC converters for smart DC
nanogrids with advanced control ancillary services, " in Proc.
IEEE 23rd Int. Workshop on Comput. Aided Modeling Des. Commun.
Links and Netw. (CAMAD), Barcelona, Spain, 2018, pp. 1-6. doi:
10.1109/CAMAD.2018.8514976.
" Efficiency requirements for residential central AC and
heat pumps to rise in 2023, " Today in Energy, July 30, 2019.
https://www.eia.gov/todayinenergy/detail.php?id=40232
(accessed Mar. 30, 2021).
S. Kouro, J. I. Leon, D. Vinnikov, L. G. Franquelo, " Grid-connected
photovoltaic systems: An overview of recent research and
emerging PV converter technology, " IEEE Ind. Electron. Mag., vol. 9,
no. 1, pp. 47-61, Mar. 2015. doi: 10.1109/MIE.2014.2376976.
A. Ginart, A. Salazar and R. Liou, " Transformerless bidirectional
inverter for residential battery storage systems, " in Proc.
IEEE Green Technol. Conf. (GreenTech), Kansas City, MO, 2016, pp.
18-23. doi: 10.1109/GreenTech.2016.11.
Y. Liu, A. Raza, K. Rouzbehi, B. Li, D. Xu, and B. W. Williams,
" Dynamic resonance analysis and oscillation damping of
multiterminal DC grids, " IEEE Access, vol. 5, pp. 16,974-16,984,
2017. doi: 10.1109/ACCESS.2017.2740567.
Biographies
Antonio Ginart (antonio.ginart@enteligent.com) is with
Enteligent, Santa Clarita, California, 91390, USA.
Bahman Sharifipour (bahman.sharifipour@enteligent
.com) is with Enteligent, Newington, New Hampshire,
03801, USA.

https://www.spglobal.com/platts/en/market-insights/latest-news/electric-power/111920-us-ev-market-sales-to-rise-to-69-million-units-by-2025-frost-amp-sullivan https://www.spglobal.com/platts/en/market-insights/latest-news/electric-power/111920-us-ev-market-sales-to-rise-to-69-million-units-by-2025-frost-amp-sullivan https://www.spglobal.com/platts/en/market-insights/latest-news/electric-power/111920-us-ev-market-sales-to-rise-to-69-million-units-by-2025-frost-amp-sullivan https://www.spglobal.com/platts/en/market-insights/latest-news/electric-power/111920-us-ev-market-sales-to-rise-to-69-million-units-by-2025-frost-amp-sullivan https://cars.usnews.com/cars-trucks/electric-cars-with-the-longest-range https://cars.usnews.com/cars-trucks/electric-cars-with-the-longest-range https://cars.usnews.com/cars-trucks/electric-cars-with-the-longest-range https://www.eia.gov/todayinenergy/detail.php?id=40232

IEEE Electrification - June 2021

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