SAE TECHNICAL PAPER SERIES The Engineering Society =For Advancing Mobility and Sea Air and Space- INTERNATIONAL Hybrid Electric Transit Bus Larry A. Viterna NASA Lewis Research Center International Truck & Bus Meeting & Exposition Cleveland, Ohio November 17-1 9, 19197 400 Commonwealth Drive, Warrendale, PA 15096-000'1 U.S.A. Tel: (41 2)776-4841 Fax:(412)776-5760 Downloaded from SAE International by University of New South Wales, Tuesday, September 18, 2018The appearance of the ISSN code at the bottom ofthiis page indicates SAE?s consent that cmpies of the paper may be made forpersod or internal use of specific clients. This cctnsent is given on the cotldion however, that the copier pay a $7.00 per article ccvy fee through the CopyrigMCleamnce Center, Inc. Operations Center, 222 Rosewood [)rive, Danvers, IulA 01 923fora)pying beyondthat permitted by Sedions 107or 108of the U.S. Copyright law. This consent does not extend toother ki~?ds of & cktribution, for advertising orpromotional puq3oses, for mating new colltxtive works, or lor resale. 15AE routinely stocks printed papers for a period of .three years following date r3f publication. Direct your orders to SAE Cusltorner Sales and Satisfaction Deparlment. Quantity reprint ratescan be obtained from tht? Customer Stales and Satisfaction Depart- ment 'To request penission to reprint a technical paper or permission to use copyrighted SAE ~wbiications in otherworks, contact the SAE I'ublitions Group. All SAE papers, sta~?dards, and sekcted h&~~ii&h&&intheSAE Gwmmase. No part of this publication may by reproducecl in any form, in an decbonic: retrieval system or otherwise, withoutthe priorwritten permission of the ptrblsher. ISSN014&7191 Copyright1997SocietyofA~mative Engineers, Inc; PcsMns andopbiom advanced in this papeirarethoseof Ule author(@ arld not necesady those of SAE The author is sdely responsible for the content of the paper. A pnxess is available by which discussions will be pririted with the paper if it is publishedl in SAE Transactions. For permission to publish this paper in tull or in part, (contact the SAE PublkatbnsGroup. Personswishing to submit papers to be considered for presentatbn or prMicatiwl thwh SAE should send the manuscript or a 300 word abstracq of a proposed manu!;cript to: Secretary, Engineering Meetings Board, SAE. Printed in USA Downloaded from SAE International by University of New South Wales, Tuesday, September 18, 2018Hybrid Electric: Transit Bus ABSTRACT A government, industry, and university cooperative is developing an advanced hybrid electric city transit bus. Goals of this effort include doubling the fuel economy compared to current buses and reducing emissions to one-tenth of current EPA standards. Unique aspects of the vehicle's power system include the use of ultra- capacitors as an energy storage system, and a planned natural gas fueled turbogenerator developed from a small jet engine. Power .from both the generator and energy storage system is provided to a variable speed electric motor attached to the rear axle. At over 15000 kg gross weight, this is the largest vehicle of its kind ever built using ultra-capacitor energy storage. This paper describes the overall power system architecture, the evolution of the control strategy, and its performance over industry standard drive cycles. INTRODUCTION New environmental emission standards are a challenge and an opportunity for industry and governments who manufacture and operate city transit buses. In addition, reduced federal support for regional transit authorities has heightened the need for buses with increased fuel economy and reduced operating costs. A bus incorporating a natural gas engine with an electric drive train and energy storage has the potential to significantly reduce emissions and fuel consumption for urban transit buses. A government and industry cooperative in Ohio is developing a transit bus using t