IEEE Power Electronics Magazine - June 2022 - 45

transmission system, and the new
HVDC system would have a higher
capacity of electric power transmission
than the HVAC system with the
same insulation level.
C. Silicon Carbide-based
Power Electronics
In both our proposed systems, dc-dc
converters play a vital role. As discussed
earlier, with the growth and
development of power electronics, it
is possible to design high efficiency
dc-dc converters. The advent of high
frequency transformers or solid-state
transformers (SSTs) have made it possible to achieve high
efficiency ac-ac conversions. Implementation of conversion
stages in SSTs utilize power electronics. In our system, the
LVDC and MVDC conversions can be handled by Si IGBT
transistors as they have adequate performance in the 1-2 kV
range. As the breakdown voltage increases, due to limited
performance, the highest voltage rating of the state-of-art
commercial Si IGBT has been 6.5 kV for the last 15 years.
These intrinsic physical limits become a barrier to achieving
higher performance power conversion. Therefore, the
implementation of HVDC conversion will require transistor
ratings that are much higher than commercially available Si
IGBT ratings. SiC transistors have a higher breakdown voltage
as compared to their Si counterparts. However, Si
IGBTs have a significant cost advantage over SiC transistors
[25]. Significant manufacturing advances that have
been established in the Si industry will be required in the
SiC industry as well. Due to the emerging demand for SiC
electronics in the power and EV industries, SiC manufacThe
advent of high
frequency transformers
or solid-state
transformers have
made it possible
to achieve high
efficiency ac-ac
converters.
turing can follow a similar roadmap to
the Si industry at a much faster rate
due to the existing knowledge from
the Si based semiconductor industry.
Thus, SiC transistors can be potentially
cost competitive with Si IGBTs
enabling their adoption at a larger
scale than the current scenario.
Therefore, SiC transistors are at
the heart of our proposed dc-dc power
conversion system by utilizing a SST,
as shown in Figure 8. There are extensive
research activities in the implementation
of SSTs for ac-ac, dc-ac or
ac-ac conversions [26], [27]. There are
various topologies in consideration for employing the best
ac-ac conversion design for grid-based applications based
on SSTs. Bidirectional power flow is a key required feature
for implementation in our proposed power network. Due to
the wide range of dc-dc voltage converters in our proposed
system, a highly scalable and modular converter is required.
There are various transformer-coupled and direct-coupled
conversion topologies in active research. Direct-coupled
converter topologies require heavy filtering components
and are suitable for MV-to-MV conversions. Transformercoupled
converter topologies are suitable LV-to-MV conversions.
We will be extrapolating the transformer-coupled
topology for MVDC-to-HVDC conversion to facilitate the
end-to-end dc power network illustrated in Figure 7. The
topology utilized in our system will be the bidirectional
soft switching resonant converter as shown in Figure 8. The
modularity of this topology as well as elimination of heavy
filtering components reduce system complexity as well.
We will be focusing on the power electronics aspect of the
Wind Energy With
Battery Bank Storage
Complete End-to-End dc Power
Network for New dc Loads and
Existing ac Loads
HVDC to
MVDC
Converter
Station
HVDC Transmission
LVDC MVDC
dc-dc
Converter
MVDC to
HVDC
Converter
Station
Utilizing the Available
ac Infrastructure With
dc Power Network
PV With Battery Bank
Storage
HVDC to HVAC
Converter Station
FIG 7 Proposed concept of the end-to-end dc power-based architecture for existing and new loads.
June 2022 z IEEE POWER ELECTRONICS MAGAZINE 45
HVAC MVAC
Existing Load
MVDC Distribution
Substation
Desalination Plant
(dc Bus)
EV
Charging
Station
Cement Factory Plant
(dc Bus)
IEEE Power Electronics Magazine - June 2022

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