Inductive Charging of Ultracapacitor Electric Bus

Paul Griffith,J Ronald Bailey,Dan Simpson

doi:10.3390/wevj1010029

Paul Griffith, J Ronald Bailey + Show 1 more

Open Access

https://doi.org/10.3390/wevj1010029

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Abstract

Many public transit agencies are exploring ways in which alternative fuels can be utilized to reduce our nation’s dependency on imported oil and to avoid the environmental impacts associated with the combustion of petroleum products. Of all the alternative fuel options, electricity is among the most desirable in terms of affordability, availability, security, and sustainability. Unfortunately, limitations in battery technology result in electric vehicle operating ranges that are much lower than those of internal combustion-powered vehicles. Although opportunity charging is one strategy for increasing the driving range of electric buses by means of a series of brief recharges during normally scheduled midday layovers, it has yet to be embraced by the transit industry, in part because of the difficulties involved in having drivers connect and disconnect the bus from the charger at regular intervals throughout the day. Roadway-mounted inductively-coupled power transfer systems effectively remove this constraint by automating the charge process, thereby obviating the need for driver intervention. Ultracapacitor energy storage systems offer advantages over battery systems for such applications.

Highlights

TO ULTRACAPACITORSUltracapacitors are electrochemical capacitors that have unusually high energy densities when compared with common capacitors; they are of particular interest in automotive applications for hybrid vehicles and as supplementary storage for battery electric vehicles [4]
A recent Federal Transit Administration report to Congress indicates that battery electric buses require only about one-third the fuel cost per mile than the cheapest propulsion strategy, and only about one-quarter the fuel cost as diesel propulsion; even greater fuel cost savings accrue
Opportunity charging is one strategy for increasing the driving range of pure electric buses by means of a series of brief recharges during normally scheduled midday layovers, it has yet to be embraced by the transit industry, in part because of the difficulties involved in having drivers connect and disconnect the bus from the charger at regular intervals throughout the day

Summary

BACKGROUND

Battery-electric buses are widely recognized as the most environmentally benign of all the alternativelyfueled public transportation options, even when emissions from the power plants that provide the electricity to recharge the batteries are included in the analysis [1]. Recent battery developments have produced incremental improvements in battery energy density, thereby enabling modest improvements in vehicle range, such advances have generally come at increased cost and do not remedy the other shortcomings noted above (new concerns have arisen such as some relating to safety). Modified operational strategies, such as increased frequency inductive charging, can improve daily range capabilities without relying on battery advances. Ultracapacitors are farther along in development with products already having been installed in a number of buses, albeit as components of hybrid-electric and diesel-electric systems rather than in pure-electric buses

INTRODUCTION

INDUCTIVE CHARGING SYSTEM

Findings

SUMMARY AND CONCLUSIONS