magnetochemistry
Article
Chassis Influence on the Exposure Assessment of a Compact EV
during WPT Recharging Operations
Valerio De Santis
1,
* , Luca Giaccone
2
and Fabio Freschi
2
Citation: De Santis, V.; Giaccone, L.;
Freschi, F. Chassis Influence on the
Exposure Assessment of a Compact
EV during WPT Recharging
Operations. Magnetochemistry 2021, 7,
25. https://doi.org/10.3390/
magnetochemistry7020025
Academic Editor: Jamie L. Manson
Received: 9 January 2021
Accepted: 2 February 2021
Published: 7 February 2021
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1
Department of Industrial and Information Engineering and Economics, University of L’Aquila,
67100 L’Aquila, Italy
2
Dipartimento Energia “G. Ferraris”, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy;
luca.giaccone@polito.it (L.G.); fabio.freschi@polito.it (F.F.)
* Correspondence: valerio.desantis@univaq.it
Abstract: In this study, the external magnetic field emitted by a wireless power transfer (WPT) system
and the internal electric field induced in human body models during recharging operations of a
compact electric vehicle (EV) are evaluated. The magneticfield is calculated with a hybrid scheme
coupling the boundary element method with the surface impedance boundary conditions in order
to fit the multiscale open-boundary characteristics of the problem. A commercial software is then
used to perform numerical dosimetry. Specifically, two realistic anatomical models, both in a driving
position and in a standing posture, are considered, and the chassis of the EV is modeled either as
a currently employed aluminum alloy and as a futuristic carbon fiber composite panel. Aligned
and misaligned coil configurations of the WPT system are considered as well. The analysis of the
obtained results shows that the International Commission on Non-Ionizing Radiation Protection
(ICNIRP) reference levels are exceeded in the driving position, especially for the carbon fiber chassis,
whereas the system is compliant with the basic restrictions, at least for the considered scenarios.
Keywords: computational electromagnetics; electric vehicle; EMF safety; low frequency dosimetry;
wireless charging; wireless power transfer
1. Introduction
Air quality is becoming a health problem in many cities around the world. This is
mainly due to the transportation sector, which is one of the main contributors towards
global climate change and CO
2
emissions [1]. Thus, the usage of compact electric vehicles
(EVs), together with the development of new mobility services, is the most sustainable
solution, at least in urban areas. However, despite having a wide appeal, EV deployment
on a global scale is still hampered by the battery technology and charging infrastructure [2].
These drawbacks can be resolved through static or dynamic wireless power transfer (WPT)
systems and their widespread applications in an improved charging infrastructure for
EVs [3].
Another challenge pertinent to compact EVs is related to the choice of the chassis
materials. Indeed, small EVs have to combine both mechanical strength, since they are
seen as unsafe vehicles by most of the users, and light weight to extend battery life or
increase vehicle performances. Current materials employed for the car body are aluminum
(Al) alloys, but in the future, advanced lightweight materials, such as carbon fiber (CF)
composite panels, could be widely used [4]. If, on the one hand, the latter can reduce the
weight and the emission of the vehicles, on the other hand, the reduced conductivities of
CF materials, which yield to lower shielding capabilities, arise more concerns about the
EMF safety of passengers and bystanders.
This paper therefore deals with the evaluation of the human exposure to the magnetic
field emitted by a WPT system aimed to recharge the battery of a compact car, namely
a FIAT 500, when both Al and CF chassis are considered. The standalone design of the
Magnetochemistry 2021, 7, 25. https://doi.org/10.3390/magnetochemistry7020025 https://www.mdpi.com/journal/magnetochemistry