**6. Discussion**

**•** A general design guideline is to place the power devices and their connections as far from the passengers as possible. However, a vehicle usually provides little room to maneuver in this sense, especially in the case of hybrid electric vehicles. The battery stack, the electronic converters, and the motor should be as far away as possible from the passengers. Batteries are usually placed just under the seats, in order to minimize risks in case of crash. However, this involves bringing them closer to the passengers. A compromise should be reached. **•** Complementary, power devices should be oriented so that the magnetic field suffered by the passengers is minimized. As described in Section 4, some power equipment such as batteries and inverters could generate stronger fields in some specific directions [63, 64]. Therefore, their relative direction with respect to the passengers should be carefully chosen. **•** Wires of the same type should be as close as possible of each other: both DC wires must be taped together; similarly, the three‐phase AC wires must be taped together, preferably in a triangular disposition. This way, the magnetic field generated by each cable in the interior

**•** Wires should be as short as possible, except when this involves bringing them closer to the

**•** When placing batteries below the seats, the battery pack can be redesigned in order to allow terminals to be placed at the bottom. This would increase the distance from the stack connections to the passengers in a value equal to the height of the battery cells. This is very convenient, given that those connections are usually close to the occupants, they carry currents up to hundreds of amperes, and it is very difficult to place them together so the magnetic field generated by all of them as a whole is cancelled out. Naturally, the chemistry of the batteries must allow this inverted position, which is not a problem with lithium‐based technologies. Notice that this action does not necessarily increase the distances between the

If further actions were necessary in order to reduce the magnetic field generated by the EV,

**•** Longer distances between power equipment and passengers are always welcome. As discussed in Section 2, front‐wheel traction drives are usually better suited to provide such

**•** In the same sense, in‐wheel motor technology [65] allows the devices inside an EV to be distributed in a much more flexible way. The space reserved for the conventional internal combustion motor could be occupied by the battery stack instead, which would mean that

**•** The higher the voltages, the lower the currents and the magnetic field, but the electric field could become higher (considering a quasistatic approximation [8], higher voltages, and higher du/dt will imply higher Coulomb electric field, but lower currents involve lower magnetic fields and thus lower Faraday electric field during transients [62]). Nonetheless, high on‐board voltages may be hazardous in case of a crash, so once again a compromise

of the vehicle will be cancelled by the rest.

64 Modeling and Simulation for Electric Vehicle Applications

passengers and the cells themselves.

these additional measures may prove helpful:

no field‐generating devices would be placed under the seats.

passengers.

longer distances.

would be necessary.

Magnetic field exposure is a matter of growing concern in the society. Recently, low‐intensity exposure is receiving much attention due to its possible hazardous effects on human health in the long term. However, uncertainty is high and there is still much research to be done. In this sense, short‐term effects are proven and well known, while long‐term effects remain to be found (although some theoretical bases and some experimental results point to the existence of potential hazardous effects [23]). With respect to EVs in particular, results presented so far in the scientific literature suggest that this concern is not scientifically justified, at least according to current standards and guidelines, which only take short‐term exposure into account. In general, exposure levels in EVs are low when compared to ICNIRP's and IEEE's recommended levels, but high when compared to other daily exposures such as those suffered at home or at work. This increase in overall magnetic field exposure is what generates concern, despite the lack of scientific proof.

Uncertainty is not the only worrying aspect of magnetic field exposure in EVs. Some emerging and promising technologies, such as SiC power electronics, could pose a significant threat, given that they allow for higher switching frequencies. Certainly, there are many aspects involved, and therefore deep analysis is required before drawing any conclusions. However, it is clear that replacing silicon‐based IGBTs with SiC MOSFETs could change the spectrum of the magnetic field inside the vehicle drastically, for better or for worse. In this sense, there are already a few publications that alert about a worsening in EMC phenomena when using SiC technology [68].

Paradoxically, some scientific results suggest that low‐intensity low‐frequency magnetic fields could have beneficial effects on human health. Certainly, these usually refer to medical treatments based on EMFs, but still knowledge is scarce about what will happen to EV passengers in the long term. Other experts have mentioned that even if magnetic fields have undesired effects on humans, it is perfectly possible that our bodies have inbuilt mechanisms to compensate for these effects [23]. Once again, further research is needed.

Finally, the authors would like to state that driving style has a strong influence on magnetic field exposure. In this regard, those drivers that favor aggressive styles (strong accelerations and deep regenerative braking) will be exposed to stronger magnetic fields. Efficient driving does not only reduce fuel consumption and maintenance needs; it also reduces magnetic field exposure.
