IEEE Power Electronics Magazine - September 2022 - 22

(a)
W
Conducted EMI: Si vs. SiC (Active lnversion)
110
120
100
50
60
70
80
90
106
Freq (Hz)
(b)
FIG 8 (a) A 250 kW SiC inverter that can switch at 60 kHz (left)
and a 250 kW Si inverter that switches at 30 kHz (right). (b)
Conductive EMI Si versus SiC when both motor drives work in
the inversion mode [31].
1.0355 MHz effective frequency, and a 38.4 kW/kg specific
power density [33], [34].
Product developments and research demonstration
of SiC-based power converters for aerospace applications
have been more focused on
high power electric machine drives.
Figure 11 shows GE Aviation's 200
kW integrated starter generator controller
for MAE. The unit utilizes
GE's 1200 V SiC MOSFETs packed
in liquid cooled power modules that
features GE's Power Overlay technology.
The maximum coolant temperature
can reach 105 °C.
Figure 12 shows a 2.4-kV1MW
3-level active neutral-pointclamped
(ANPC) inverter for
hybrid-electric propulsion, which
was designed and demonstrated by
GE. The inverter features a SiC+Si
hybrid approach and achieves 99%
efficiency and a power density of
12 kVA/kg [35].
107
As newest development, multiple medium voltage megawatt
PD free demonstrations of SiC-based propulsion
drives are being developed and tested by both industry
and university led teams. Figure 13(a) shows a submodule
for a 2-kV 1-MVA integrated modular motor drive (IMMD)
that is currently being developed under a project funded by
NASA and led by The Ohio State University (OSU) in collaboration
with the University of Wisconsin, the University
of Maryland, and North Carolina A&T University. The submodule
utilizes SiC power modules from Wolfspeed. Figure
13(b) shows the submodule during tests in the altitude
chamber. The submodule achieves PD free operation at 700
V and 87 torr [air pressure at 56 000 ft (17068.8 m)]. Figure
14(a) shows three stages of these submodules configured
in series for a 2-kV, 1-MVA test with inductive loads. Figure
14(b) shows three phase " B " currents, each from a different
stage. During the test, the SiC power modules were
switching at 40 kHz. Based on results of double pulse tests
and the inductive load tests, the estimated efficiency of all
stages together is higher than 99%. The power density of
the submodule is 35.36 kW/kg [36].
Figure 15(a) and (b) shows overThe
higher switching
speed and higher
switching frequency of
WBG devices will
improve the efficiency
and power quality of
power electronics
circuits. But at the
same time, more EMI
related issues could
be expected.
22 IEEE POWER ELECTRONICS MAGAZINE z September 2022
all design and current assembly status
of the 2-kV, 1-MVA IMMD. Figure
15(c) shows the configuration of
planned IMMD tests inside an altitude
chamber at the NASA Electric
Aircraft Testbed (NEAT). If successful,
this would be the first megawatt
level integrated motor drive with PD
free operation at high altitude.
Summary and Thoughts
WBG devices are gradually finding
their ways into aerospace applications.
Besides the challenges that
were discussed in this article, thermal
management, EMI mitigation
and dv/dt filters designs, and current
sharing between power modules
SiC - 60 kHz
Si
SiC
461G
FIG 9 600 W GaN-based NIBB for space applications [32].
L x W x H = 95 x 69 x 25 [mm]
L
Mag (dBµV)
IEEE Power Electronics Magazine - September 2022

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