The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE’s peer review process under the supervision of the session organizer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form o r by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. ISSN 0148-7191 Positions 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. SAE Customer Service: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerService@sae.org SAE Web Address: http://www.sae.org Printed in USA 2009-24-0158 Energy efficiency and potentials of electric motor types for wheel hub applications Johann Willberger Andrés Eduardo Rojas Rojas Haymo Niederkofler Graz University of Technology, Austria Institute of Automotive Engineering Copyright © 2009 SAE International ABSTRACT Nearly all OEMs worldwide try to electrify their powertrain systems. This is certainly a necessity in order to fulfill the gradually changing and challenging political requirements concerning environmental restrictions. Electric motors offer potential characteristics to overcome these challenging tasks. Today, induction and synchronous motors represent reasonable alternatives to conventional combustion engines, even due to their established assembling and their relatively low cost production. This article compares the energy consumption of induction motors (IM), synchronous motors with surface mounted magnets (SPM) and synchronous motors with interior mounted magnets (IPM) at different driving cycles. The paper intends to identify a suitable electric motor type for wheel hub applications. INTRODUCTION Finding a suitable electric motor as propulsion unit for cars is difficult but a highly up to date research area. As the age of crude oil gradually finishes and political arrangements all over the world force a reduction of global carbon dioxide emissions, almost all OEMs worldwide put in a lot of knowledge to electrify their powertrain systems. By now, hybrid propulsion systems come to mass production, however, these systems can be considered as a further step aiming at pure electric vehicles in the future. Nevertheless, the search for suitable electric motor types is an ongoing process, as an ideal traction machine cannot be specified in literature. This fact results because of the large number of different characteristics of electric motor types. Each motor type has pros and cons making them individually favourable for different load cycles. The most promising electric motor techniques are certainly induction motors and synchronous motors. Their assembling is established, moreover, the production of the motor types is relatively low-cost. The comparison of different motor types is often inaccurate because of different use and therefore different optimization criteria. A reasonable comparison between electric motor types has to consider equal geometric restrictions and traction requirements. Beside that, additional optimization criteria (e.g. weight, efficiency) have to be taken into account. The present article focuses on the comparison of induction motors (IM) and synchronous motors (SPM, IPM) at different load cycles considering equal optimization criteria. The geometric restrictions of all motor types are based on their potential application within a 16 inch wheel rim. The traction requirements result from a motor operation analysis of different load cycles based on a predefine