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

Junqing Lan,Akimasa Hirata

doi:10.3390/en13143635

Abstract

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.

Highlights

There has been increased interest in wireless power transfer (WPT) systems owing to their convenience in charging wireless devices such as mobile phones, household appliances, and electric vehicles (EVs) (e.g., [1])
This study investigates the effects of loudspeakers on the in situ electric field in a driver’s body exposed to EV WPT systems, where the vehicle body is made of carbon fiber reinforced plastic (CFRP) or aluminum
The WPT-generated magnetic field distribution is significantly altered around the woofer in the CFRP vehicle and around the tweeter in the aluminum vehicle where obvious discontinuity and local enhancement can be observed

Summary

Introduction

There has been increased interest in wireless power transfer (WPT) systems owing to their convenience in charging wireless devices such as mobile phones, household appliances, and electric vehicles (EVs) (e.g., [1]). EVs have attracted significant attention as an alternative for reducing the air pollution produced by diesel powered vehicles. Electric vehicles with a WPT system do not require power transmission wiring, the possibility of electrical leakage from the plug under wet conditions is reduced [2]. Electromagnetic field leakage from the WPT system, which is the main source of leakage in the EV, may pose potential health risks to humans. Another potential field source is the motor. The field leakage from the motor is very localized [3]

Methods

Results

Conclusion