LOW FREQUENCY MAGNETIC FIELDS INSIDE CARS

Electromagnetic exposure levels of electric vehicle drive motors to cochlear implanted passenger

In order to evaluate the effects of electromagnetic radiation generated by the dual-drive motors of an electric vehicle on special passengers with cochlear implanted, this study considers a cochlear implanted passenger as the research object, takes the drive motors in electric vehicle as the exposure source. A calculation model including the vehicle body, brain tissue, skull, eyes, human body, and cochlear implant is built, and the finite element method is used to calculate the induced electric field ([Formula: see text]), specific absorption rate (SAR), and temperature changes in different tissues and organs of the passenger's body. The results show that the maximum value of [Formula: see text] on the human body surface is 60.8 mV/m at the ankle. The [Formula: see text] around the cochlear implant inside the human head is also high, with a maximum value of 57.1 mV/m. The maximum SAR of the human body is [Formula: see text], which also appears near the cochlear implant. Besides, the maximum temperature rise of the human body, brain tissue, and cochlear implant is 0.10 °C, 0.28 °C, and 0.0076 °C, respectively. Calculation shows that the [Formula: see text] and SAR of the human body and different tissues are much lower than the safety limit specified in the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and the temperature rise does not reach the thermal damage threshold in the guidelines. The electric field around the electrode tip and the surface of the cochlear implant, the temperature rise of the cochlear implant also meet the requirements of the ICNIRP and the International Organization for Standardization's 14708-7 medical device standard. The results could enrich the study on the electromagnetic environment of electric vehicles and provide references for the design and improvement of cochlear implants and electromagnetic exposure protection for vehicles.

Electromagnetic exposure level of pure electric vehicle inverter to human body in different seating positions

The market share of pure electric vehicle (PEV) as a green transportation steadily increases as the global demand for renewable energy sources and environmentally friendly mobility continues to increase. However, during PEV operation, the inverter system, as the key power conversion device, generates strong electromagnetic field in the local space. Long-term exposure to such electromagnetic environments may have potential effects on human body. In this study, the electromagnetic environment model of the PEV body, human body and simplified inverter is established. The finite element software, COMSOL Multiphysics, is used to calculate and analyse the variations in the induction field in different tissues of the driver and rear passenger, caused by the electromagnetic field generated by the inverter system operating at maximum power. The electromagnetic exposure level of the driver and rear passenger is assessed. Results show significant differences in the electromagnetic exposure levels of different seating positions in the vehicles. The electromagnetic exposure level in the driver's body is higher than that of the rear passenger, but it does not exceed the exposure limits defined by the International Commission for Non-ionizing Radiation Protection. This finding effectively complements the study on evaluating the safety of the electromagnetic environment of PEV and improves public awareness.

Study on the safety assessment and protection design of human exposure to low-frequency magnetic fields in electric vehicles

As the power performance of electric vehicles continues to improve, the human body may be exposed to electromagnetic threats in the cabin. This study tested an electric vehicle to analyze the low-frequency magnetic field distribution in the cabin and to assess the safety of human low-frequency magnetic field exposure. A simulation analysis of human electromagnetic exposure was carried out to obtain the magnetic flux density, induced electric field strength and induced current density, and the test results were much lower than the limits specified in GB8702-2014 and the International Commission on Non-Ionizing Radiation Protection, and the relative error between the simulation results and the test results was <15%. This paper investigates the frequency, driving current, vehicle body material and cable layout to explore the law of human body induced electromagnetic field changing with power cable current, and provides theoretical reference for the design of human body low-frequency magnetic field protection.

Complex Electromagnetic Issues Associated with the Use of Electric Vehicles in Urban Transportation

The electromagnetic field (EMF) in electric vehicles (EVs) affects not only drivers, but also passengers (using EVs daily) and electronic devices inside. This article summarizes the measurement methods applicable in studies of complex EMF in EVs focused on the evaluation of characteristics of such exposure to EVs users and drivers, together with the results of investigations into the static magnetic field (SMF), the extremely low-frequency magnetic field (ELF) and radiofrequency (RF) EMF related to the use of the EVs in urban transportation. The investigated EMF components comply separately with limits provided by international labor law and guidelines regarding the evaluation of human short-term exposure; however other issues need attention-electromagnetic immunity of electronic devices and long-term human exposure. The strongest EMF was found in the vicinity of direct current (DC) charging installations-SMF up to 0.2 mT and ELF magnetic field up to 100 µT-and inside the EVs-up to 30 µT close to its internal electrical equipment. Exposure to RF EMF inside the EVs (up to a few V/m) was found and recognized to be emitted from outdoor radiocommunications systems, together with emissions from sources used inside vehicles, such as passenger mobile communication handsets and antennas of Wi-Fi routers.

Effect of Loudspeakers on the In Situ Electric Field in a Driver Body Model Exposed to an Electric Vehicle Wireless Power Transfer System

This study computationally evaluates the effect of loudspeakers on the in situ electric field in a driver body model exposed to the magnetic field from a wireless power transfer (WPT) system in an electric vehicle (EV), one with a body made of carbon fiber reinforced plastic (CFRP) and the other made with aluminum. A quasi-static two-step approach was applied to compute the in situ electric field. The computational results showed that the magnetic field distribution generated by the WPT is significantly altered around the loudspeakers, and shows obvious discontinuity and local enhancement. The maximum spatial-average magnetic field strength in the driver’s body was increased by 11% in the CFRP vehicle. It was 2.25 times larger than the reference levels (RL) prescribed in the International Commission of Non-Ionizing Radiation Protection (ICNIRP) guidelines in 2010. In addition, we found that the in situ electric field computed by the line- and volume-averaging methods were stable if the top 0.1% voxels are excluded. The maximum value was well below the basic restriction (BR) of the ICNIRP guidelines. Nevertheless, the presence of the loudspeaker led to increments in the electric field strength in parts of the human body, suggesting the potential influence of permissible transmitting power in the WPT system. The maximum electric field strength in the thigh and buttock with the woofer, increased by 27% in the CFRP vehicle. The arm value was up to 3 times higher than that obtained without the tweeter in the aluminum vehicle. Moreover, this study found that the maximum electric field strength depended on the location of the loudspeaker with respect to the WPT system and the separation from the driver model. Therefore, the loudspeaker should be considered when evaluating the maximum in situ electric field strength in the vehicle body design stage.