1、The Winning Solar Car Douglas R. Carroll SAE InternationalThe Winning Solar Car A Design Guide for Solar Race Car TeamsOther SAE books of interest: Lightweight Electric/Hybrid Vehicle Design by Ron Hodkinson and John Fenton (Order No. R-316) Alternative Fuels Guidebook by Richard L. Bechtold (Order
2、No. R-180) For more information or to order a book, contact SAE Customer Service at 400 Commonwealth Drive, Warrendale, PA 15096-0001; Website: http:/store.sae.org; E-mail: CustomerServicesae.org; Phone: 1-877-606-7323 (USA or Canada) or 724-776-4970 Fax: 724-776-0790The Winning Solar Car A Design G
3、uide for Solar Race Car Teams Douglas R. Carroll Warrendale, Pa. Copyright 2003 SAE International eISBN: 978-0-7680-5271-8All 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, photocopyin
4、g, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests, contact: SAE Permissions 400 Commonwealth Drive Warrendale, PA 15096-0001 USA E-mail: permissionssae.org Tel: 724-772-4028 Fax: 724-772-4891 Library of Congress Cataloging-in-Publication D
5、ata Carroll, Douglas R. The winning solar car : a design guide for solar race car teams / Douglas R. Carroll. p. cm. Includes bibliographical references and index. ISBN 0-7680-1131-0 1. Solar carsDesign and construction. I. Title. TL222.C37 2003 629.2295dc21 2003052648 SAE International 400 Commonwe
6、alth Drive Warrendale, PA 15096-0001 USA E-mail: CustomerServicesae.org Tel: 877-606-7323 (inside USA and Canada) 724-776-4970 (outside USA) Fax: 724-776-1615 Copyright 2003 SAE International ISBN 0-7680-1131-0 SAE Order No. R-343 Printed in the United States of America.To my wife Karla, for putting
7、 up with me as I spent an awful lot of our time learning about solar cars.Preface Development of this book began in 1997, after the 1997 Sunrayce event. I had then been involved in designing and building three solar cars that partici- pated in the 1993, 1995, and 1997 Sunrayce events, respectively.
8、As the coach and advisor for a university solar car team, I had the problem of losing some key students with each project. The new students joining the team had the same design misconceptions that the veteran students had when they began and would want to make the same design mistakes that had been
9、made on previous cars. Making the same design mistakes again provides a good edu- cational experience for the students but does not further knowledge of solar car design. To make progress and continually improve our design efforts, I developed a course on solar car design and wrote notes to support
10、the course. The purpose of the course was to get the new students up to speed, and the course focused on what is important in designing a competitive solar car. The notes became a little more formal each time I offered the course, and evolved into this book on solar car design. The material in this
11、book is based on my experiences designing and building five solar cars over the last twelve years. I have tried to keep the book gen- eral and offer design options so that it is not just about how the University of Missouri-Rolla team designs solar cars, but there is a certain amount of bias in our
12、design philosophy. The book was designed to be used in a course that is open to upper-level students majoring in any field of engineering, math- ematics, or science. Solar car design is an interdisciplinary topic, and the book was written to be suitable for the junior, senior, and graduate students
13、who would be responsible for designing the car. Students entering the course are assumed to have a fundamental understanding of calculus, differential equations, physics, and chemistry. The book provides an introduction to all aspects of designing, manufacturing, and racing solar cars but does not p
14、ro- vide all of the details on any topic. Design groups will have to go deeper than what is provided in this book to design any of the systems on the car. Every- one on the team needs to have a fundamental understanding of what is involved in designing, building, and racing the car. Understanding th
15、e “big picture“ will help team members make design and manufacturing trade-offs viiThe Winning Solar Car to stay on schedule and allow time to test and practice racing the car. Testing and practice are an important part of being successful in the competition. To do well in a solar car race, the team
16、 must have a good car, good drivers, good weather information, good strategy, and a well-trained support team. Doing a poor job on any of these elements will hurt the performance of the team in the race. The main focus of this book is on designing the car because that is the most difficult and time-
17、consuming part of the project, but the team needs to recognize that the car is not the whole project. Driver train- ing, accurate weather forecasting, race strategy, and practice in driving the race route make a huge difference in how well the team performs in the competition. The first two chapters
18、 in the book are on energy management, and the infor- mation in these chapters is helpful when doing design trade-offs and devel- oping a strategy for racing the car. Chapter 2 includes information on how to drive the car efficiently and is helpful in driver training. Chapter 3 focuses on design met
19、hodology and project management and provides an introduc- tion to the general design process. The remaining chapters are about design- ing the different subsystems of the car. In each chapter, I have referred the reader to books and articles that I have found helpful on designing and build- ing sola
20、r cars. The goal of the book is to provide an introduction to all aspects of designing, building, and racing solar cars. viiiAcknowledgments When I began working with the solar car team at the University of Missouri- Rolla, I was a new assistant professor and had little understanding of how to desig
21、n a solar car or how to coach a college car design team. I have received help from many people over the years, and without their help, I could not have been successful. Chancellor John T. Park and Dean O. Robert Mitchell saw value in the project and helped the team get the support, facilities, and f
22、unding needed even in the early years when the team was not very success- ful. The project would have died at an early date without their support and encouragement. Dean Lee W. Saperstein, Dr. D. Ronald Fannin, Dr. E. Keith Stanek, Dr. Ashok Midha, Dr. Henry A. Wiebe, and Dr. David A. Summers provid
23、ed office space, manufacturing facilities, and technical assistance from their departmental resources in support of the project. Mr. L. John Tyler spent countless volunteer hours developing an efficient process for manufacturing the body of the car, developing an efficient pro- cess for evaluating a
24、nd testing batteries, and teaching students how to manu- facture many of the mechanical components of the car. He has been a key person in developing the practical knowledge required to manufacture a solar car. Dr. C.H. Wu spent many hours explaining to me and the students how solar cells work and h
25、ow to build a solar array. Dr. K.M. Isaac spent many hours working with me on the aerodynamics of solar cars. Dr. Donald L. Cronin spent many hours teaching me about tire and suspension design. Dr. Paul D. Hirtz was the president and project manager for the team for several years and helped us under
26、stand the importance of applying the disci- pline of project management to the solar car design project. I owe special thanks to Dr. Patrick J. Starr for talking with me about how he coaches the design teams at the University of Minnesota. He was my mentor in learning how to be an engineering design
27、 team coach. Dr. Starr also helped me learn about the technical aspects of designing the chassis and suspension of the solar car. In learning to coach and organize a team, I have also had help- ful conversations with my colleagues at other universities: Dr. Michael T. Shelton and Ms. Tina Shelton at
28、 California State Polytechnic University-Pomona, ixThe Winning Solar Car Mr. Art Boyt at Crowder College, Dr. Scott Tolbert at the University of North Dakota, Dr. Joe Ritter and Dr. Steve Shedd at Principia College, Dr. Dennis Waugaman at Texas A&M University, and Mr. Richard T. Whelove at the Unive
29、rsity of Missouri-Columbia. I also would like to thank Mr. Steve McMullen for his help over the years in developing battery systems. All solar car teams owe a great deal of thanks to Mr. Dan Eberle, Ms. Kate von Reis, and Ms. Andrea Pagee for staffing the solar car racing headquarters and organizing
30、 the races. There would be no solar car races in the United States without their commitment. We also owe many thanks to Mr. Howard Wilson, Mr. Richard King, General Motors Corporation, Electronic Data Systems, and the U.S. Department of Energy for their support of solar car racing. xTable of Content
31、s Chapter 1 Introduction 1 A. Identification of the Problem 1 B. Solar Car Racing 3 C. Energy Available and Distances Traveled in Solar Car Racing 8 D. Homework Assignment 12 E. References 13 Chapter 2 Energy Management Modeling of Solar Car Performance 15 A. Purpose of Modeling. 15 B. Aerodynamics
32、15 C. Rolling Resistance 17 D. Homework Assignment 19 E. Solar Array Power 21 F. Battery Efficiency 27 G. Motor-Drive System 31 H. Parasitic Losses 31 I. Gravitational Energy 32 J. Kinetic Energy 33 K. Modeling: Summary 33 L. Homework Assignment 40 M. Hilly, More Realistic Terrain 41 N. Homework Ass
33、ignment 43 O. Extra Credit Homework: Milford Track Homework (Study of How Hills Affect Solar Car Efficiency).46 P. Extra Credit Homework: Heartland Park Track (Study of How Sharp Corners Affect Solar Car Efficiency)47 Q. References 48 Chapter 3 Design Methodology 51 A. Introduction 51 B. Time and Re
34、sources 52 xiThe Winning Solar Car C. Study History 57 D. Control Innovation 58 E. Design Process 59 F. Solar Car Design Process 63 G. References 70 Chapter 4 Solar Array Design 71 A. Solar Cell Fundamentals 71 B. Open-Circuit Voltage 74 C. Short-Circuit Current 75 D. Solar Cell EfficiencySolar Spec
35、trum 76 E. Solar Cell Model 80 F. Illumination Level IL 86 G. Temperature 88 H. Coatings .91 I. Wiring the Solar Array 92 J. Shading of the Array 97 K. Cell Matching 97 L. Angling of Cells in a String 97 M. Shingling of Cells 100 N. Series-Paralleling of Cells 102 O. Bypass Diodes. 104 P. Array Diag
36、nosis and Repair 106 Q. Matching Array Voltage with Battery Voltage 109 R. Power Point Trackers 110 S. Extreme Low-Light/No-Light OFF Switch 115 T. Homework 116 U. References. 118 Chapter 5 Aerodynamics of Solar Cars 121 A. Fundamentals 121 B. Car Body Shape 124 C. Camber 125 D. Reynolds Number 134
37、E. Body Drag Area Calculations 135 F. Body Drag Introduction 136 G. Canopy Drag 148 xiiTable of Contents H. Other Shapes Protruding into the Airstream 153 I. Drag Caused by the Wheels 155 J. Ventilation 164 K. Wingtip Drag 167 L. Induced Drag 168 M. Summary 169 N. Side Winds 170 O. Computational Flu
38、id Mechanics (CFM) 173 P. Wind Tunnel Testing 174 Q. References 175 Chapter 6 Composite Materials 177 A. Body Structure 177 B. Body Strength Requirement 178 C. Attachment Points 179 D. Body Support Plates or Angles 180 E. Quality of Lay-Up 182 F. Box Beam Construction 184 G. Mold and Body Constructi
39、on 185 H. Strength and Stiffness of Honeycomb and Foam Core Composites 190 I. Composites Assignment 204 J. References .206 Chapter 7 Car Balance and Spring Rates 207 A. Car Balance and Moment of Inertia 207 B. Selecting Spring Rates. 211 C. Homework 218 D. References 220 Chapter 8 Tires and Rolling
40、Resistance 221 A. Tire Selection 221 B. Rolling Resistance Phenomenon 226 C. Energy Loss Model for Tire Misalignment 229 D. References 239 Chapter 9 Front Suspension Design 241 A. Wheel Selection 241 xiiiThe Winning Solar Car B. Brake Design 242 C. Homework for Brakes 252 D. Hub and Spindle 254 E. S
41、uspension and Chassis Design Philosophy .259 F. Front-End Geometry and Steering 259 G. Homework for Front Suspension Geometry 273 H. References 275 Chapter 10 Rear Suspension, Drive, and Chassis Structure 277 A. Rear Suspension and Drive Design 277 B. Drivetrain 284 C. Electric Motors 288 D. Chassis
42、 Structure 293 E. References 297 Chapter 11 Battery Systems 299 A. Battery Fundamentals 299 B. Fundamentals of Battery Chemistry 302 C. Lead-Acid Batteries 307 D. Silver-Zinc Batteries 312 E. Nickel-Cadmium (NiCd) Batteries 313 F. Nickel-Hydrogen and Nickel-Metal-Hydride (NMH) Batteries 315 G. Lithi
43、um-Ion and Lithium-Polymer Batteries 316 H. Charge-Discharge Curves 318 I. Battery Modeling 320 J. Battery Pack Modeling 322 K. Wiring of the Battery Box 325 L. Battery Safety 326 M. References 326 Chapter 12 Electrical Systems 329 A. Introduction 329 B. Wiring Diagram 329 C. Fuses. 332 D. Wire Sizi
44、ng 333 E. Connectors and Switches 334 F. Electrical Subsystems 336 xivTable of Contents Index 343 About the Author 375 xvChapter 1 Introduction A. Identification of the Problem The first step in the design process is to define the problem as clearly as possible. There is an iterative process to desi
45、gn, and the design team may not understand the problem well enough at first to give a clear definition. In this case, the problem should be defined as clearly as possible. The definition will be refined as the team works through the design process. Design meth- odology is discussed in more detail in
46、 Chapter 3. As an example of a race car design problem, circle track racing is more famil- iar than solar car racing 1-1. The problem to be solved is to get the car to go around the track as quickly as possible, as illustrated in Fig. 1.1. Speed in the corners is limited primarily by the amount of t
47、raction between the tires and the road. Acceleration is limited by the power the engine can provide, the Fig. 1.1 Circle track racing. 1The Winning Solar Car efficiency and inertia of the drivetrain, the weight of the car, the aerody- namic drag, and traction between the tires and the road. Braking
48、is limited by the performance of the braking system and traction between the tires and the road. The strategy for circle track racing is as follows: 1. Go around the corner as fast as possible without sliding sideways off the track. 2. Accelerate out of the corner as quickly as possible and continue
49、 accelerat- ing down the straightaway. 3. At the last possible minute, hit the brakes to slow down just enough to keep from sliding off the track in the next corner. From the race strategy, it appears that the most important design aspects for the car are cornering, acceleration, and braking. The next step in problem definition is to determine what aspects of the car contribute most to corner- ing, acceleration, and braking. Cornering Performance 1. The tires should be selected so they have a high coefficient of friction between the rubber and the track. 2. A downward aerodynamic for
