An Efficient Wireless Power Transfer System to Balance the State of Charge of Electric Vehicles

As an alternate form in the road transportationsystem, electric vehicle (EV) can help reduce the fossil-fuelconsumption. However, the usage of EVs is constrained by thelimited capacity of battery. Wireless Power Transfer (WPT) can increase the driving range of EVs by charging EVs inmotionwhen they drive through a wireless charging laneembedded in a road. The amount of power that can be suppliedby a charging lane at a time is limited. A problem here iswhen a large number of EVs pass a charging lane, how toefficiently distribute the power among different penetrationslevels of EVs? However, there has been no previous researchdevoted to tackling this challenge. To handle this challenge, wepropose a system to balance the State of Charge (called BSoC) among the EVs. It consists of three components: i) fog-basedpower distribution architecture, ii) power scheduling model, and iii) efficient vehicle-to-fog communication protocol. The fogcomputing center collects information from EVs and schedulesthe power distribution. We use fog closer to vehicles ratherthan cloud in order to reduce the communication latency. Thepower scheduling model schedules the power allocated to eachEV. In order to avoid network congestion between EVs and thefog, we let vehicles choose their own communication channelto communicate with local controllers. Finally, we evaluateour system using extensive simulation studies in NetworkSimulator-3, MatLab, and Simulation for Urban MObilitytools, and the experimental results confirm the efficiency ofour system.

I. Introduction

Intelligent Transportation System (ITS) utilizes traffic information, communication, and computing capabilities and it provides an integrated system consisting of people, roads, and vehicles to increase traffic efficiency and decrease traffic congestion. As a component of the future generation ITS, the design and implementation of Electric Vehicles (EVs) have drawn much attention in recent years. Several works have already been demonstrated the future impact of EVs on a road transportation system [1]–[4] such as economical energy consumption and environment protection. In an EV, the onboard battery supplies the energy demands of the vehicle. However, EVs have some battery-related issues such as heavy weight, long charging time, large size, and short driving range. To alleviate these problems, wireless charging or Wireless Power Transfer (WPT) technique arise. It makes the charging procedures more convenient by allowing charging procedure take place automatically without having any physical contact between utility power supply and electric battery. It transfers power from grid to an EV's battery while it is moving through a charging lane embedded in a road. An EV spends very little time on top of the charging coils. The shorter duration of time requires higher power levels in charging infrastructure so that higher amount of power can be transferred. However, the investment for charging infrastructure goes up to meet the demand for higher power. Therefore, the amount of power that can be supplied by a charging lane at a time is always limited. A problem here is when a large number of EVs pass a charging lane, how to efficiently distribute the power among them when the infrastructure is not able to fulfill all the demands? However, there has been no previous research devoted to tackling this challenge.