IEEE Power Electronics Magazine Compendium - March 2018 - 30

vehicle-the current smoothing results are dramatic, as
shown in Figure 18.

ure 19 shows an excerpt of the measured currents taken
during testing.

Battery current smoothing with
lic in Vehicle and lic on grid side

Power Pulsation Reduction

GEM Vehicle Battery Current and
Li-Ion Capacitor Current (A)

The implementation of local energy storage was shown to
be very effective in reducing the ratio of peak-to-average
The final experiment was to use the LiC on both the grid
current, resulting in lower power pulside as active parallel and in the vehisations of the grid-supplied power and
cle as passive parallel. In this test, a
vehicle battery pack charging power.
pair of ESL LiC 40-V modules are conTable 1 summarizes the previously
nected to the power supply output via
The LiC system
mentioned results. In Table 1, the
a dc-dc converter, and a second
provides the transient
experimental test results for grid-side
series-connected pair of 40-V LiC modenergy to meet the
power supply current and vehicle tracules are placed in the GEM vehicle, as
tion drive electronics load current are
shown schematically in Figure 2 and
power requirement of
given as peak values for comparison.
experimentally in Figure 11. As with
the charging coils.
The use of electrochemical capacithe Maxwell Technologies UC module,
tors as high burst power sources and
the LiC modules are also precharged
sinks has been shown to dramatically
to match the GEM pack voltage. Figreduce power pulsations at both the
grid and vehicle battery pack. The implications are that grid
15
demand response resources will be substantially reduced
GEM Battery Current
by the use of local high-power capacitor storage at roadside
Li-Ion Capacitor Current
10
WPT base stations and in vehicle to mitigate battery ripple
5
current during in-motion charging for the case of energized
and sequenced roadway embedded wireless charging coils.
0
Figure 20 shows ORNL's concept for dynamic WPT installed
-5
in special charging lanes on highways. This concept was presented to the U.S. Department of Transportation research
-10
and innovative technologies administration to assist in long-15
term highway research [50].
The key attributes of this concept are that WPT modules
-20
0
1
2
3
4
5
6
7
8
9
are controllable, modular, scalable, and replaceable, and the
Time(s)
energized track sections are powered by highway dc distribution and multifailure-point survivable. The coil sequencfig 19 The in-vehicle LiC and battery currents (LiC current a 13.4 A
ing is synchronous, with the vehicle under charge regardand battery current a 2.6 A).
less of speed or congestion. WPT
roadside units (RSUs) supply the dc
distribution from grid connections
Traffic
at various intervals along the highLanes
WPT
way corridor.
Lane

Median

RSU

ibution
dc Distr
e
PT Lan

RSU

Side View

Top View

fig 20 The dynamic WPT system installed in special highway lanes.

IEEE PowEr ElEctronIcs MagazInE

z March 2014

Traffic
Lanes

Cover Plate
Windings
Ferrite Pieces
dc Distribution
and Power
Command

Conclusions
This article focused on just one of the
many technical challenges posed by
the dynamic charging of EVs-power
pulsations. Equally challenging, if not
more technically challenging, are
concerns over lateral alignment for
lane keeping and optimum power
transfer coupling, low-latency private
and secure communications for vehicle to infrastructure, highway construction and maintenance, utility
power distribution to WPT RSUs,
time of use and revenue structure,
and so on. Not listed among these

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine Compendium - March 2018