Lightweight Electric/Hybrid Vehicle Design Prelim.pm6 21-04-01, 1:52 PM1 Lightweight Electric/ Hybrid Vehicle Design Ron Hodkinson and John Fenton OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI Prelim.pm6 21-04-01, 1:52 PM3 iv Contents Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd A member of the Reed Elsevier plc group First published 2001 © Reed Educational and Professional Publishing Ltd 2001 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress ISBN 0 7506 5092 3 Prelim.pm6 21-04-01, 1:52 PM4 Contents v Contents Preface vii About the authors ix Introduction xi Part 1 Electromotive Technology (Ron Hodkinson MSc MIEE) 1 1 Current EV design approaches 3 1.1 Introduction 3 1.2 Case for electric vehicles 3 1.3 Selecting EV motor type for particular vehicle application 15 1.4 Inverter technology 21 1.5 Electric vehicle drives: optimum solutions for motors, drives and batteries 24 2 Viable energy storage systems 29 2.1 Electronic battery 29 2.2 Battery performance: existing systems 29 2.3 Status of the aluminium battery 35 2.4 Advanced fuel-cell control systems 39 2.5 Waste heat recovery, key element in supercar efficiency 50 3 Electric motor and drive-controller design 56 3.1 Introduction 56 3.2 Electric truck motor considerations 56 3.3 Brushless DC motor design for a small car 58 3.4 Brushless motor design for a medium car 61 3.5 Brushless PM motor: design and FE analysis of a 150 kW machine 64 3.6 High frequency motor characteristics 68 3.7 Innovative drive scheme for DC series motors 73 4 Process engineering and control of fuel cells, prospects for EV packages 80 4.1 Introduction 80 4.2 Reforming and other hydrogen feedstocks 82 4.3 Characteristics, advantages and status of fuel cells 83 4.4 Thermodynamics of fuel cells 84 Prelim.pm6 21-04-01, 1:52 PM5 vi Contents 4.5 Process engineering of fuel cells 87 4.6 Steps towards the fuel-cell engine 89 4.7 Prospects for EV package design 93 4.8 Fuel-cell vehicles and infrastructure 96 4.9 The PNGV programme: impetus for change 98 Part 2 EV Design Packages/Design for Light Weight 103 (John Fenton MSc MIMechE) 5 Battery/fuel-cell EV design packages 105 5.1 Introduction 105 5.2 Electric batteries 105 5.3 Battery car conversion technology 115 5.4 EV development history 119 5.5 Contemporary electric car technology 122 5.6 Electric van and truck design 128 5.7 Fuel-cell powered vehicles 135 6 Hybrid vehicle design 141 6.1 Introduction 141 6.2 Hybrid drive prospects 143 6.3 Hybrid technology case studies 146 6.4 Production hybrid-drive cars 156 6.5 Hybrid passenger and goods vehicles 164 7 Lightweight construction materials and techniques 173 7.1 Introduction 173 7.2 The ‘composite’ approach 173 7.3 Plastic mouldings for open canopy shells 178 7.4 Materials for specialist EV structures 182 7.5 Ultra-lightweight construction case study 191 7.6 Weight reduction in metal structures 192 8 Design for optimum body-structural and running-gear performance efficiency 199 8.1 Introduction 199 8.2 Structural package and elements 200 8.3 ‘Punt’-type structures 209 8.4 Optimizing substructures and individual elements 211 8.5 Designing against fatigue 217 8.6 Finite-element analysis (FEA) 218 8.7 Case study of FEA for EVs and structural analysis assemblies 223 8.8 Running gear design for optimum performance and lightweight 223 8.9 Lightweight vehicle suspension 231 8.10 Handling and steering 232 8.11 Traction and braking systems 235 8.12 Lightweight shafting, CV jointing and road wheels 241 8.13 Rolling resistance 243 Index 251 Prelim.pm6 21-04-01, 1:52 PM6 Preface vii Preface The stage is now reached when the transition from low-volume to high-volume manufacture of fuel cells is imminent and after an intense period of value engineering, suppliers are moving towards affordable stacks for automotive propulsion purposes. Since this book went to press, the automotive application of fuel cells for pilot-production vehicles has proceeded apace, with Daewoo, as an example, investing $5.9 million in a fuel-cell powered vehicle based on the Rezzo minivan, for which it is developing a methanol reforming system. Honda has also made an important advance with version 3 of its FCX fuel-cell vehicle, using a Ballard cell-stack and an ultracapacitor to boost acceleration. Its electric motor now weighs 25% less and develops 25% more power and start-up time has been reduced from 10 minutes to 10 seconds. Ballard have introduced the Mk900 fuel cell now developing 75 kW (50% up on the preceding model). Weight has decreased and power density increased, each by 30%, while size has dropped by 50%. The factory is to produce this stack in much higher volumes than its predecessor. While GM are following the environmentally-unfriendly route of reformed gasoline for obtaining hydrogen fuel, Daimler Chrysler are plumping for the methanol route, with the future option of fuel production from renewables; they are now heading for a market entry with this technology, according to press reports. A recent DaimlerChrysler press release describes the latest NECAR, with new Ballard Stack, which is described in its earlier Phase 4 form in Chapter 5, pp. 139–140. NECAR 5 has now become a methanol-powered fuel cell vehicle suitable for normal practical use. The environmentally friendly vehicle reaches speeds of more than 150 kilometres per hour and the entire fuel cell drive system – including the methanol reformer – has been installed in the underbody of a Mercedes- Benz A-Class for the very first time. The vehicle therefore provides about as much space as a conventional A-Class. Since the NECAR 3 phase, in 1997, the engineers have succeeded in reducing the size of the system by half and fitting it within the sandwich floor. At the same time, they have managed to reduce the weight of the system, and therefore the weight of the car, by about 300 kg. While NECAR 3 required two fuel cell stacks to generate 50 kW of electric power, a single stack now delivers 75 kW in NECAR 5. And although the NECAR 5 experimental vehicle is heavier than a conventional car, it utilizes energy from its fuel over 25% more efficiently. The development engineers have also used more economical materials, to lower production cost. Methanol ‘fuel’ could be sold through a network of filling stations similar to the ones we use today. The exhaust emissions from ‘methanolized’ hydrogen fuel cell vehicles are very much lower than from even the best internal combustion engines. The use of methanol-powered fuel-cell vehicles could reduce carbon-dioxide emissions by about a third and smog-causing emissions to nearly zero. Methanol can either be produced as a renewable energy source from biomass or from Preface-a.pm6 21-04-01, 1:53 PM7 viii Preface natural gas, which is often burned off as a waste product of petroleum production and is still available in many regions around the world. To quote D-C board members, ‘there have already been two oil crises; we are obligated to prevent a third one,’ says Jürgen E. Schrempp, Chairman of the Board Of Management of DaimlerChrysler. ‘The fuel-cell offers a realistic opportunity to supplement the ‘petroleum monoculture’ over the long term.’ The company will invest about DM 2 billion (over $ 1 billion) to develop the new drive system from the first prototype to the point of mass production. In the past six years the company has already equipped and presented 16 passenger cars, vans and buses with fuel cell drives–more than the total of all its competitors worldwide. Professor Klaus-Dieter Vöhringer, member of the Board of Management with responsibility for research and technology, predicts the fuel cell will be introduced into vehicles in several stages ‘In 2002, the company will deliver the first city buses with fuel cells, followed in 2004 by the first passenger cars.’ The electric-drive vehicle has thus moved out of the ‘back-room’ of automotive research into a ‘design for production’ phase and already hybrid drive systems (IC engine plus electric drive) have entered series production from major Japanese manufacturers. In the USA, General Motors has also made very substantial investments with the same objective. There is also very considerable interest throughout the world by smaller high-technology companies who can use their knowledge base to successfully enter the automotive market with innovative and specialist-application solutions. This last group will have much benefit from this book, which covers automotive structure, and system design for ultra-light vehicles that can extend the range of electric propulsion, as well as electric-drive technology and EV layouts for its main-stream educational readership. NECAR5 fuel-cell driven car. Preface-a.pm6 21-04-01, 1:53 PM8 Preface ix About the authors Electro-technology author Ron Hodkinson is very actively involved in the current value engineering of automotive fuel-cell drive systems through his company Fuel Cell Control Ltd and is particularly well placed to provide the basic electro-technology half of this work. He obtained his first degree in electrical engineering (power and telecommunications) from the Barking campus, of what is now the University of East London, on a four-year sandwich course with Plessey. At the end of the company’s TSR2 programme he moved on to Brentford Electric in Sussex where he was seconded on contract to CERN in Switzerland to work on particle-accelerator magnetic power supplies of up to 9 MW. He returned to England in 1972 to take a master’s degree at Sussex University, after which he became Head of R&D at Brentford Electric and began his long career in electric drive system design, being early into the development of transistorised inverter drives. In 1984 the company changed ownership and discontinued electronics developments, leading Ron to set up his own company, Motopak, also developing inverter drives for high performance machine tools used in aircraft construction. By 1989 his company was to be merged with Coercive Ltd who were active in EV drives and by 1993 Coercive had acquired Nelco, to become the largest UK producer of EV drives. In 1995 the company joined the Polaron Group and Ron became Group Technical Director. For the next four years he became involved in both machine tool drives and fuel cell controls. In 1999 the group discontinued fuel-cell system developments and Ron was able to acquire premises at Polaron’s Watford operation to set up his own family company Fuel Cell Control Ltd, of which he is managing director. He has been an active member of ISATA (International Society for Automotive Technology and Automation) presenting numerous papers there and to the annual meetings of the EVS (Electric Vehicle Seminar). He is also active in the Power Electronics and Control committees of the Institution of Electrical Engineers. Some of his major EV projects include the Rover Metro hybrid concept vehicle; IAD electric and hybrid vehicles; the SAIC fuel-cell bus operating in California and Zetec taxicabs and vans. Co-author John Fenton is a technology journalist who has plotted the recent course in EV design and layout, including hybrid-drive vehicles, in the second half of the book, which also includes his chapters on structure and systems design from his earlier industrial experience. He is an engineering graduate of the Manchester University Science Faculty and became a member of the first year’s intake of Graduate Apprentices at General Motors’ UK Vauxhall subsidiary. He later worked as a chassis-systems layout draughtsman with the company before moving to automotive consultants ERA as a chassis-systems development engineer, helping to develop the innovative mobile tyre and suspension test rig devised by David Hodkin, and working on running- gear systems for the Project 378 car design project for BMC. With ERA’s subsequent specialization on engine systems, as a result of the Solex acquisition, he joined the Transport Division of Unilever, Preface-a.pm6 21-04-01, 1:53 PM9 x Preface working with the Technical Manager on the development of monocoque sandwich-construction refrigerated container bodies and bulk carriers for ground-nut meal and shortening-fat. He was sponsored by the company on the first postgraduate automotive engineering degree course at Cranfield where lightweight sandwich-construction monocoque vehicle bodies was his thesis subject. He changed course to technology-journalism after graduating and joined the newly founded journal Automotive Design Engineering (ADE) as its first technical editor, and subsequently editor. A decade later he became a senior lecturer on the newly founded undergraduate Vehicle Engineering degree course at what is now Hertfordshire University and helped to set up the design teaching courses in body-structure and chassis-systems. He returned to industry for a short period, as a technology communicator, first Product Affairs Manager for Leyland Truck and Bus, then technical copywriter and sales engineer (special vehicle operations). With the merging of ADE with the Institution of Mechanical Engineers JAE journal he had the opportunity to move back to publishing and subsequently edited the combined journal Automotive Engineer, for fifteen years, prior to its recent transformation into an international auto-industry magazine. x About the authors Preface-a.pm6 21-04-01, 1:53 PM10 Introduction xi Introduction 0.1 Preface This book differs from other automotive engineering texts in that it covers a technology that is still very much in the emerging stages, and will be particularly valuable for design courses, and projects, within engineering degree studies. Whereas other works cover established automotive disciplines, this book focuses on the design stages, still in process for electric vehicles, and thus draws on a somewhat tentative source of references rather than a list of the known major works in the subject. The choice of design theory is also somewhat selective, coming from the considerable volume of works the disciplines of which are combining to make the production electric vehicle possible. 0.1.1 BIBLIOGRAPHIC SOURCES Electrical propulsion systems date back virtually to the time of Faraday and a substantial body of literature exists in the library of the Institution of Electrical Engineers from which it is safe only to consider a small amount in relation to current road vehicle developments. Similarly a considerable quantity of works are available on aerospace structural design which can be found in the library of the Royal Aeronautical Society, and on automotive systems developments within the library of the Institution of Mechanical Engineers. With the massive recent step-changes in capital investment, first in the build-up to battery-electric vehicle development, then in the switch to hybrid drive engineering, and finally the move to fuel-cell development – it would be dangerous to predict an established EV technology at this stage. A good deal of further reading has been added to the bibliographies of references at the ends of each chapter. This is intended to be a source of publications that might help readers look for wider background, while examining the changes of direction that EV designers are making at this formative stage of the industry. The final chapter also lists publications which seem to be likely sources of design calculations pertinent in designing for minimum weight and has a table of nomenclature for the principal parameters, with corresponding symbol notation used in the design calculations within the text of the chapters. 0.1.2 CONTEXT AND STRUCTURE The current period of EV development could be seen as dating from a decade or so before the publication of Scott Cronk’s pivotal work published by the Society of Automotive Engineers in 1995, Building the E-motive Industry. As well as pulling together the various strings of earlier EV development, the book takes a very broad-brush view of the many different factors likely to affect intro-a.pm6 21-04-01, 1:54 PM11 [...]... unusually low fuel consumption born out of low-drag and lightweight construction This is the philosophy that the authors of Lightweight Electric/Hybrid Vehicle Design are trying to follow in a work which looks into the technologies in greater depth The book is in two parts, dealing with (a) electromotive technology and (b) EV design packages, lightweight design/ construction and running-gear performance Ron... 1929–1930 Harrop, G., The future of the electric vehicle, a viable market? Pearson Professional, 1995 J.F intro-a.pm6 30 21-04-01, 1:54 PM Current EV design approaches PART ONE ELECTROMOTIVE TECHNOLGY Cha1-a.pm6 1 21-04-01, 1:40 PM 1 2 Cha1-a.pm6 Lightweight Electric/Hybrid Vehicle Design 2 21-04-01, 1:40 PM Current EV design approaches 3 1 Current EV design approaches 1.1 Introduction The environmental... separate suppliers, with many aspects of R&D and design being divested to systems suppliers Relationships between sub-units are too delicate to be left to market-type arrangements in this ‘associationalist’ way of working intro-a.pm6 23 21-04-01, 1:54 PM xxiv Lightweight Electric/Hybrid Vehicle Design 0.4 Electric-drive fundamentals While battery-electric vehicles were almost as common as IC-engined ones,... 7.0 ld 5.5 % % D Div iver ert t 3400 60 xxviii Lightweight Electric/Hybrid Vehicle Design help in rapid build-up of generator EMF The resulting problem is heat build-up of these series windings under heavy vehicle- operating loads Efforts to counteract this by reducing the length of the shunt coil creates the further difficulty of slow excitation after vehicle coasting Since the brushes of the generator... technology as well as convincing motor industry management of the need for radical designs which will enable the best performance to be obtained from this propulsion technology The massive sensitivity of the general public to unconventional vehicle intro-a.pm6 15 21-04-01, 1:54 PM xvi Lightweight Electric/Hybrid Vehicle Design Fig 0.1 Alcan's use of 5754 aluminium alloy substituted for steel in the Ford... for fuel related to pollution Cha1-a.pm6 5 21-04-01, 1:40 PM 6 Lightweight Electric/Hybrid Vehicle Design National grid Iron + Hydrocarbon supply SERVICE STATION Storage at service station Water 20% waste heat 80% Hydrogen Thermal catalytic reformer Turbine Generator Hydrogen storage tank Vehicle storage tank Air 10 litres in 4 minutes VEHICLE Hydrogen Desulphurization Fuel cell Waste heat 40% 60%... electricity for ‘charging up’ the flywheel A 2-minute recharge would be required for the Fig 0.2 Parry flywheel-electric hybrid rail bus intro-a.pm6 17 21-04-01, 1:54 PM xviii Lightweight Electric/Hybrid Vehicle Design flywheel to propel the vehicle its maximum distance of two miles; so more frequent stops are recommended to reduce recharge time, 0.5 km being the optimum A hybrid version with additional LPG... city of La Rochelle where electric cars such as this Peugeot 106 are made available to its citizens intro-a.pm6 19 21-04-01, 1:54 PM xx Lightweight Electric/Hybrid Vehicle Design a ‘partnership’ chain of long-term suppliers and appoint a project leader to coordinate design, development and production, leading a cross-company team Such leadership would carry the authority for detailed cost investigations... during the conceptual period of engineering design 0.2.1 FARTHER-REACHING FACTORS OF ‘TOTAL DESIGN Since the electric vehicle has thus far, in marketing terms, been ‘driven’ by the state rather than the motoring public it behoves the stylist and product planner to shift the emphasis towards the consumer and show the potential owner the appeal of the vehicle Some vehicle owners are also environmentalists,... considerable sums of money being invested by makers of conventional vehicles to raise ‘refinement’ levels In the 1960s, despite the public appeals made by Ralph Nader and his supporters, car safety would not sell As traffic densities and potential maximum speed levels have increased intro-a.pm6 13 21-04-01, 1:54 PM xiv Lightweight Electric/Hybrid Vehicle Design over the years, safety protection has come home to . Lightweight Electric/Hybrid Vehicle Design Prelim.pm6 21-04-01, 1:52 PM1 Lightweight Electric/ Hybrid Vehicle Design Ron Hodkinson. born out of low-drag and lightweight construction. This is the philosophy that the authors of Lightweight Electric/Hybrid Vehicle Design are trying to follow