400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2003-01-3382 Eddy Current Couplings for Mild Hybrid Trucks H. Razavi, M. Lamperth and P. Anpalahan Imperial College, London Reprinted From: NGV’s and Hybrid-Powered Trucks (SP–1815) 2003 SAE International Truck and Bus Meeting and Exhibition Fort Worth, Texas November 10-12, 2003Downloaded from SAE International by University of Minnesota, Monday, July 30, 2018All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4891Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-1615Email: Customer [email protected] ISSN 0148-7191Copyright © 2003 SAE InternationalPositions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE.The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of Minnesota, Monday, July 30, 20182003-01-3382 Eddy Current Couplings for Mild Hybrid Trucks H. Razavi, M. Lamperth and P. Anpalahan Imperial College, London Copyright © 2003 SAE Internati onal ABSTRACT This paper looks at new possibilities to design mild hybrid power trains for truck applications using an eddy current assisted coupling between the main diesel engine and the electrical machine. This will allow the start-up of the engine by means of the eddy current coupling and only once the speed of the engine is synchronized, the conventional friction clutch will be engaged. Since no physical contact is established during the start-up period, the life of the system is prolonged due to a ”wear-free'' method of power transmission. Analysis of the coupling requirements is presented based on the specification of a 7.5 ton delivery vehicle for use in urban areas. Analytical and finite element models are used to predict the performance of the coupling. These results are then compared to measurements. INTRODUCTION Diesel powered small delivery trucks are widely used to deliver goods to inner-city shops and businesses. These vehicles operate from distribution centers located on the periphery of a town using the motorway network to commute into town. The duty cycle can hence be clearly distinguished between a highway part and an urban part. The latter requires much less power than the highway part. Driving on a highway is a very efficient way of transport as the prime mover unit (PMU) operates under nearly constant load, close to its optimal efficiency point. The operation of the vehicle in the urban and congested areas is the opposite from emissions and efficiency point of views. The engine is forced to operate off design point which in turn leads to low efficiency and undesirable operating conditions. Additionally a large part of the urban duty cycle requires vehicle to stop and for the rest the top speed required is generally below 30 miles per hour. Based on this understanding a mild hybrid powertrain is being proposed that offers two distinct favorable types of operation. For the highway driving the powertrain remains as in conventional vehicle whereas for urban driving the vehicle is solely driven by a