Driving Range of Electric Vehicles Charged by Wireless Power Transfer

Electric vehicles (EVs) are limited by the on-board batteries in terms of driving range and charging duration. In this paper, the driving range of electric vehicles (EVs) charged by wireless power transfer (WPT) systems is investigated. Specifically, a force-based vehicle model is coupled with a simple extended battery model to simulate the impact of wireless charging on the state of charge of the accumulator sub-system. In total, three different scenarios, i.e., urban, highway and combined driving are presented. The trade-off between having a standalone charging option versus combined dynamic and quasi-dynamic wireless charging is outlined and minimum system requirements, such as charging power levels and road coverage, for unlimited range are established. Furthermore, the effect of external factors such as ambient temperature, battery age and wireless transfer efficiency is investigated. It is shown that employing combined charging at medium power levels is sufficient to achieve unlimited range compared to high power requirements for standalone charging. Finally, safety concerns regarding human exposure are addressed with lower charging powers.

I. Introduction

The transportation sector is amongst the main contributors towards global climate change and CO₂ emissions [1]. For instance, it was responsible for about 60% of the global oil consumption in 2017. Therefore, the need for a clean alternative is high [2]. Electric vehicles (EVs) are such an alternative technology. Compared to conventional internal combustion engines (ICEs), electric motors are more efficient and do not rely on burning fuel within the vehicle, hence do not produce emissions while using them. On one hand, the fuel used for electricity generation has a strong influence on the possible CO₂-reduction. One the other hand, EVs allow to incorporate renewable energy into the transportation sector on a large scale. Yet with a share of only 0.5% in global light duty vehicles and 2 million newly sold EVs in 2018, the widespread deployment on a global scale is still hampered [3], [4]. Main drawbacks result from the battery technology and charging infrastructure used, causing higher investments, longer charging times, and lower driving capacity often named ‘range anxiety’, with respect to conventional ICE-vehicles. To overcome these drawbacks, more charging stations and faster charging cycles are required. Conventionally, EVs use conductive charging stations to recharge. However, due to the small number of dedicated charging stations for EVs and the long waiting times it is difficult to fully exploit the potential of EV integration. In addition, handling high power cables, particularly in adverse weather conditions, can be dangerous.