IEEE Electrification Magazine - December 2017 - 16

Power quality is a
major concern for
an aircraft employing
eTaxi because of the
large power demand
required by the EDS.

as current distortion, inrush current,
voltage distortion, voltage modulation, power factor, phase balance,
and dc content.
The current distortions composed
of ac harmonics are the key design
drivers for the equipment. The requirements for current harmonics, subharmonics, and interharmonics specify
the allowable distortion as a function
of multiples of the fundamental frequency of the input voltage.
A typical current harmonic includes all odd harmonics
up to 39, with limits ranging from 10 to 0.25% of the
maximum current fundamental. The current distortion
requirement is a key design driver because it usually
significantly impacts the equipment weight. The current
distortion is also specified as a function of the equipmentrated power because the higher power equipment has
more influence on the power bus.
For ac-to-dc converters, the requirements for the dc
output are also important. These requirements include
ripple voltage and voltage droop. The ripple voltage and
voltage droop determine the dc operating range of the
output equipment, i.e, the inverters.

Passive Versus Active ac-to-dc
Power Converters for eTaxi
The passive ac-to-dc converters have dominated the aerospace power electronics industry in the past because of
the following: simplicity, lack of stringent power quality
requirements, lack of stringent EMI compliance requirements, and no need for regeneration of electric power to
the distribution bus.
The passive ac-to-dc converters usually comprise
diodes and filtering capacitors. They present low losses,
high reliability, low weight, and low volume. The main representative for a three-phase distribution bus is the threephase diode bridge, which comprises six diodes and one
smoothing capacitor in its minimal configuration. The
main disadvantages of such converters are the high level
of harmonic content in the input currents resulting from
the six-step commutation and the inability to transfer
power in the opposite direction.
As a part of the eTaxi initiative, increased-power-level
inverters up to 60 kVA have been used to deliver the required
currents translated to the required torque and power at the
TM shaft. Therefore, a more complex relationship between
various loads and the power generation system is created.
The mitigation provision is to create well-defined, stringent
power quality and EMI compliance requirements. A conventional three-phase bridge does not satisfy the new environment; complex passive filters must be added for compliance,
which leads to a substantial weight penalty.
The next improvement can be made by implementing various passive schemes with increased steps of

16

I E E E E l e c t r i f i cati o n M a gaz ine / DECEMBER 2017

commutation: the larger the number
of steps, the lower the amplitudes of
the input harmonics.
Additionally, some low-frequency
harmonics disappear with larger commutation frequency. The high-frequency harmonics are easy to mitigate
with smaller inductors and capacitors.
To increase the number of commutation steps from six to 12 or 18, the
three-phase distribution bus is converted to a six- or nine-phase bus and
then rectified. A great variety of transformers and autotransformers can be used to perform those tasks. Ganev et al.
show that 18-pulse converters are lighter than 12-pulse converters for the same harmonic requirements. Thus, designed
multipulse ac-to-dc converters experience increased weight
and volume, worsened losses, and reduced reliability. However, at this point, these solutions look most attractive for
medium-to-low-power-level applications when unidirectional power transfer only is required.
The drive for energy-efficient eTaxi imposes the need
for bidirectional power transfer. This creates an opportunity to reuse the regenerated power coming from the
dynamic braking function. Then, active rectification comes
onboard to satisfy this complex task. The most common
active rectifier is a three-phase bridge that comprises six
diodes, six switching devices, a dc link capacitor, and three
interface inductors for decoupling with the distribution
bus. To implement proper high-performance operation,
sophisticated vector control algorithms are required. This
leads to the use of additional digital signal processor
(DSP)-based control electronics with a gate driver for each
switching device.
Power quality compliance is relatively easy due to the
controllability of the input current waveshape. EMI compliance is probably more difficult due to differential- and
common-mode noises coming from the switching devices. Quite competitive ac-to-dc converters with bidirectional capability can be obtained. However, reliability is
drastically reduced due to the increased number of components and the connections between them. There is a
great variety of active rectifiers with different characteristics. Their success is application driven. Therefore, there is
no clear overall winner. Some ac-to-dc converters are not
bidirectional, e.g., Vienna rectifiers.
The analysis performed at Honeywell shows that, in
power levels above 25 kVA, active rectification is the winner from a weight and volume perspective. Consequently,
if there is no need for bidirectional operation and the
power levels are below certain levels, passive multipulse
rectification is the preferred option. Ganev et al. offer a
novel composite ac-to-dc converter that reduces the
weight and improves the performance substantially.
Thus, the threshold for the active rectification weight
advantage can be moved to 50 kW.



Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2017

IEEE Electrification Magazine - December 2017 - Cover1
IEEE Electrification Magazine - December 2017 - Cover2
IEEE Electrification Magazine - December 2017 - 1
IEEE Electrification Magazine - December 2017 - 2
IEEE Electrification Magazine - December 2017 - 3
IEEE Electrification Magazine - December 2017 - 4
IEEE Electrification Magazine - December 2017 - 5
IEEE Electrification Magazine - December 2017 - 6
IEEE Electrification Magazine - December 2017 - 7
IEEE Electrification Magazine - December 2017 - 8
IEEE Electrification Magazine - December 2017 - 9
IEEE Electrification Magazine - December 2017 - 10
IEEE Electrification Magazine - December 2017 - 11
IEEE Electrification Magazine - December 2017 - 12
IEEE Electrification Magazine - December 2017 - 13
IEEE Electrification Magazine - December 2017 - 14
IEEE Electrification Magazine - December 2017 - 15
IEEE Electrification Magazine - December 2017 - 16
IEEE Electrification Magazine - December 2017 - 17
IEEE Electrification Magazine - December 2017 - 18
IEEE Electrification Magazine - December 2017 - 19
IEEE Electrification Magazine - December 2017 - 20
IEEE Electrification Magazine - December 2017 - 21
IEEE Electrification Magazine - December 2017 - 22
IEEE Electrification Magazine - December 2017 - 23
IEEE Electrification Magazine - December 2017 - 24
IEEE Electrification Magazine - December 2017 - 25
IEEE Electrification Magazine - December 2017 - 26
IEEE Electrification Magazine - December 2017 - 27
IEEE Electrification Magazine - December 2017 - 28
IEEE Electrification Magazine - December 2017 - 29
IEEE Electrification Magazine - December 2017 - 30
IEEE Electrification Magazine - December 2017 - 31
IEEE Electrification Magazine - December 2017 - 32
IEEE Electrification Magazine - December 2017 - 33
IEEE Electrification Magazine - December 2017 - 34
IEEE Electrification Magazine - December 2017 - 35
IEEE Electrification Magazine - December 2017 - 36
IEEE Electrification Magazine - December 2017 - 37
IEEE Electrification Magazine - December 2017 - 38
IEEE Electrification Magazine - December 2017 - 39
IEEE Electrification Magazine - December 2017 - 40
IEEE Electrification Magazine - December 2017 - 41
IEEE Electrification Magazine - December 2017 - 42
IEEE Electrification Magazine - December 2017 - 43
IEEE Electrification Magazine - December 2017 - 44
IEEE Electrification Magazine - December 2017 - 45
IEEE Electrification Magazine - December 2017 - 46
IEEE Electrification Magazine - December 2017 - 47
IEEE Electrification Magazine - December 2017 - 48
IEEE Electrification Magazine - December 2017 - 49
IEEE Electrification Magazine - December 2017 - 50
IEEE Electrification Magazine - December 2017 - 51
IEEE Electrification Magazine - December 2017 - 52
IEEE Electrification Magazine - December 2017 - 53
IEEE Electrification Magazine - December 2017 - 54
IEEE Electrification Magazine - December 2017 - 55
IEEE Electrification Magazine - December 2017 - 56
IEEE Electrification Magazine - December 2017 - 57
IEEE Electrification Magazine - December 2017 - 58
IEEE Electrification Magazine - December 2017 - 59
IEEE Electrification Magazine - December 2017 - 60
IEEE Electrification Magazine - December 2017 - 61
IEEE Electrification Magazine - December 2017 - 62
IEEE Electrification Magazine - December 2017 - 63
IEEE Electrification Magazine - December 2017 - 64
IEEE Electrification Magazine - December 2017 - 65
IEEE Electrification Magazine - December 2017 - 66
IEEE Electrification Magazine - December 2017 - 67
IEEE Electrification Magazine - December 2017 - 68
IEEE Electrification Magazine - December 2017 - 69
IEEE Electrification Magazine - December 2017 - 70
IEEE Electrification Magazine - December 2017 - 71
IEEE Electrification Magazine - December 2017 - 72
IEEE Electrification Magazine - December 2017 - 73
IEEE Electrification Magazine - December 2017 - 74
IEEE Electrification Magazine - December 2017 - 75
IEEE Electrification Magazine - December 2017 - 76
IEEE Electrification Magazine - December 2017 - 77
IEEE Electrification Magazine - December 2017 - 78
IEEE Electrification Magazine - December 2017 - 79
IEEE Electrification Magazine - December 2017 - 80
IEEE Electrification Magazine - December 2017 - 81
IEEE Electrification Magazine - December 2017 - 82
IEEE Electrification Magazine - December 2017 - 83
IEEE Electrification Magazine - December 2017 - 84
IEEE Electrification Magazine - December 2017 - 85
IEEE Electrification Magazine - December 2017 - 86
IEEE Electrification Magazine - December 2017 - 87
IEEE Electrification Magazine - December 2017 - 88
IEEE Electrification Magazine - December 2017 - 89
IEEE Electrification Magazine - December 2017 - 90
IEEE Electrification Magazine - December 2017 - 91
IEEE Electrification Magazine - December 2017 - 92
IEEE Electrification Magazine - December 2017 - 93
IEEE Electrification Magazine - December 2017 - 94
IEEE Electrification Magazine - December 2017 - 95
IEEE Electrification Magazine - December 2017 - 96
IEEE Electrification Magazine - December 2017 - 97
IEEE Electrification Magazine - December 2017 - 98
IEEE Electrification Magazine - December 2017 - 99
IEEE Electrification Magazine - December 2017 - 100
IEEE Electrification Magazine - December 2017 - Cover3
IEEE Electrification Magazine - December 2017 - Cover4
http://www.nxtbook.com/nxtbooks/pes/electrification_december2019
http://www.nxtbook.com/nxtbooks/pes/electrification_september2019
http://www.nxtbook.com/nxtbooks/pes/electrification_june2019
http://www.nxtbook.com/nxtbooks/pes/electrification_march2019
http://www.nxtbook.com/nxtbooks/pes/electrification_december2018
http://www.nxtbook.com/nxtbooks/pes/electrification_september2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2018
http://www.nxtbook.com/nxtbooks/pes/electrification_december2017
http://www.nxtbook.com/nxtbooks/pes/electrification_september2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2017
http://www.nxtbook.com/nxtbooks/pes/electrification_june2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2016
http://www.nxtbook.com/nxtbooks/pes/electrification_september2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2016
http://www.nxtbook.com/nxtbooks/pes/electrification_march2015
http://www.nxtbook.com/nxtbooks/pes/electrification_june2015
http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2014
http://www.nxtbook.com/nxtbooks/pes/electrification_june2014
http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2013
http://www.nxtbook.com/nxtbooks/pes/electrification_september2013
http://www.nxtbookMEDIA.com