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General Disclaimer One or more of the Following Statements may affect this Document This document has been reproduced from the best copy furnished by the organizational source. It is being released in the interest of making available as much information as possible. This document may contain data, which exceeds the sheet parameters. It was furnished in this condition by the organizational source and is the best copy available. This document may contain tone-on-tone or color graphs, charts and/or pictures, which have been reproduced in black and white. This document is paginated as submitted by the original source. Portions of this document are not fully legible due to the historical nature of some of the material. However, it is the best reproduction available from the original submission. Produced by the NASA Center for Aerospace Information (CASI) DOE/NASA/0595-78/1 NASA CR-135341 PRELIMINARY POWER TRAIN DESIGN FOR A STATE-OF-THE-ART ELECTRIC VEHICLE Phillip Mighdoll and William F. Hahn Design and Development Division BOOZ, ALLEN 6 HAMILTON Inc. t April, 1978 Prepared for NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Lewis Research Center Under Contract NAS 3-20595 fo r U.S. DEPARTMENT OF ENERGY Electric and Hybrid Vehicle Systems Program Division of Transportation Energy Conservation (NASA-CR-135341) PRELI41NARY POWER TRAIN N78-29992 T DESIGN FOR A STATE-OF-THE-ART ELECTRIC i VEHICLE Final Report (30cz-Allen and Hamilton, Inc.) 144 p 11C A07/MF A01 rincIas CSCL 13F 03/85 27173 DOE/NASA/0595-78/ 1 NASA CR-135341 PREUMI 9ARY POWER TRAIN DESIGN FOR ,A STATE-OF-` HEART ELECTRIC VEHICLE Phillip Mighdoll and William F. Hahn Design and Development Division BOOZ, ALLEN E HAMILTON Inc. Cleveland, Ohio 44131 April, 1978 Prepared for NATIONAL AERONAUTICS AND SPACE ADMINISTRA"T"ION Lewis Research Center E Cleveland, Ohio 44135 ^. Under Contract NAS 3-20595 I 4 fo r f U.S. DEPARTMENT OF ENERGY Electric and Hybrid Vehicle Systems Program Division of Transportation Energy Conservation Washington, D.C. 20545 Under Interagency Agreement EC-77-A-31-10.44 t i- -b NOTICE This report was pr"rarl by Boox, Allen 1^ Hamilton Inc. as of work sponsored by the United States Government. Neither the Unit States rter anyemployees,of their sw ra n yof their contractors subcontractors, i or their employees, mattes any warranty, expreas or Implied, or assumes a any lNal liability or rasponsiblllty for the accuracy, completeness, or ` .. usefulness of any lnformatlan, apparatus, product or process di sclosed, or represents that Its use would not Infringe privately owned rights. PREFACE This report presents a summary of work performed by the Design and Development Division of Bcoz, Alien S Hamilton Inc. under NASA contract NAS 3-20595. The authors wish to acknowledge the support of Mr. C.S. Skinner, who served as officer-in- charge. Mr. R.R. Lasecki, Mr. A.D. Szpak and Mr. L.L. xgrabik were the maim technical contributors. Mr. J. Brennand of the General Research Corporation graciously provided a copy of the computer program which was used in Chapter 3.0. Mr. Mighdoll was the project engineer and Dr. Hahn was the program manager. iii TABLE OF CONTENTS ^e PREFACE lit GLOSSARY vil 1. 0 SUMMARY l 2.0 INTRODUCTION 3.0 ASSESSMENT OF THE STATE-OF-THE-ART IN ELECTRIC 5 VEHICLE BOWER TRAIN TECHNOLOGY 31 EXISTING ELECTRIC VEHICLES 6 3. 1.1 Electric Vehicles Designed by the Enthusiast 7 i. S' 3.1.2 Domestic Commercial Electric Vehicle Conversions 0 3.1.3 Domestic Electric Vehicles Designed From the 9 i Ground Up ^ l ^ I 3,1,4 Foreign Electric Vehicles 12 3.1.5 Summary and Design Trends 16 { 3,2 MOTOR AND CONTROLLERS 23 i 3.2.1 Alternating Current (AC) Motors 23 3.2.2 AC Motor Controllers 24 3.2.3 Direct Current (IBC) Motors 25 3.2.4 DC !Motor Controller 27 a 3.2.5 Vehicle Control Requirements and Summary 30 3.3 MECHANICAL ELEMENTS OF AN ELECTRIC VEHICLE POWER 32 TRAIN 3.3.1 Transmissions 32 3.3.2 Differentials and Axles 45 k Iv ai c-• 3.3.3 Brakes 46 I 3.3.4 Tires 48 j 3.3.5 Bearings 54 4 4.0 STATE-OF-THE-ART POWER TRAIN DESIGN 57 ` 4.1 REQUIREMENTS 57 r 4.2 PRELIMINARY COMPONENTS SELECTION 59 7 1[.3 ANALYTICAL MODEL 61 f. 4.3.1 Component Mathematical Models 61 4.3.7 Computer Program Description 65 I 4.3.3 Acceleration Profile 69 4 1' 4.3.4 Range of an Ideal Vehicle 71 4.3.5 Sensitivity Analysis 1 r: 4.3.6 Motor Sizing ;F 4.4 POWER TRAIN DESIGN 4.4.1 Power Train Components 4.4.2 Motor/Trarnsmission Selection 4.4.3 Recommended State-of-the-Art Power Train 4.4.4 Predicted Range of the State-of-the-Art Power Train t 5.0 IMPROVED POWER TRAIN DESIGNS I 5.1 PERSPECTIVE ON RANGE IMPROVEMENTS 5.2 NEAR TERM TECHNICAL IMPROVEMENTS 5.3 SEPARATELY EXCITED MOTOR SYSTEMS v I d tL jS.3.1 Computer- Simulation Model 141 ? S.3.2 Description and Performance Calculations 143 5.4 MISCELLANEOUS IMPROVEMENTS 116 yy 5.5 DISCRETE GEAR CHANGE AUTOMATIC TRANSMISSION 117 I I ^ r 6.0 CONCLUSIONS 123 t ^ k ? REFERENCES 124 BIBLIOGRAPHY 130 1 i y i S 1 ^ [ 6 F 1 t^Q i 1 L 1^1 d i I d v! -. 7F ' 4 1 {4 L _i t Ji r, GLOSSARY AC Alternating Current r i AMC AM General Corporation CVT Continuously Variable Transmission DC Direct current 1 DoE U.S. Department9Y of Energy ^ ERDA Energy Research and Development Administration i ^i EV Electric Vehicle j EVA Electric Vehicle Associates, Inc. GE The General Electric Company GRC General Research Corporation HB HB Electrical Manufacturing Company ICE Internal Combustion Engine MG MG Motor Division, British Leyland, Ltd. NASA-LERC National Aeronautics and Space Administration, Lewis Research Center SAE Society of Automotive Engineers SCR Silicon Controlled Rectifier i SOA State-of-the-Art VAN Volkswap en 1.0 SUMMARY As part of the national effort to stimulate the use of electrically powered vehicles for transportation, the design of urban passenger electric vehicles has been reviewed. This study considers automotive and electric vehicle technologies with specific emphasis on the power train. Its purpose is to objectively identify an "optimum" power train system which can be assembled with state-of-the-art components, to predict the performance of such a system, and to identify and evaluate improvements which might benefit vehicle performance. In the past, power trains consisting of controller, motor, transmission, running gear, wheels, brakes and tires have been incorporated into a wide variety of vehicle designs. Most of the designs are based on conventional chassis, but superior performance has been demonstrated in complete designs, such as the Copper Development Association town car. In this program several configurations and combinations of off-the-shelf components were suggested by a study of existing electric vehicles, a review of related technology and an application of engineering judgment. These candidate electric vehicle power trains were evaluated quantitatively and by computer simulation to identify the system which can achieve maximum range over the SA i_ J227a Schedule D driving cycle. This state-of-the-art power train employs regenerative braking and consists of a series wound DC motor, SCR chopper controller, electrically controlled V-belt continuously variable transmission, radial tires, and drum brakes. Analysis predicts that a vehicle weighing 1,587 kg (3500 lbs.), using 16 E11-106 lead-acid batteries and employing this power train would achieve a range of about 50 km (31.2 miles) over the Schedule D cycle. The electric vehicle literature, technical judgment and interviews with a broad spectrum of persons within the industry, provided suggestions for potential near term technical advances, which could be applied to improve the state-of-the-art power train design. These include means to extend vehicle range, as well as features to enhance the commercial success of electrically powered passenger vehicles. Several systems involving shunt wound DC motors were considered in detail. An improved power train was selected which employs a high speed separately excited motor with armature and field control. A single ratio speed reducer replaces the multi-ratio transmission. On the Schedule D cycle, a vehicle with this power train can achieve a range benefit of approximately 20 percent when compared with a power train of similar weight which uses state-of-the-art components. 1 R v i i 2.0 INTRODUCTION By the turn of the century, automobiles powered by the Internal combustion engine (ICE) and battery powered electrics were competing to replace the horse in urban centers.. At their peak acceptance, around 1912, It has been estimated that several hundred thousand electric vehicles were in Use throughout the world (Ref.1) . The features of the present gasoline powered ICE vehicle have developed over a long period of -efinement. These Include: • Favorable initial cost, • Good performance, s Inexpensive fuel, and • Long range. England has continued to build and favor electrically powered vans (milk floats), but the electric vehicle has virtually disappeared from the American market. In the U.S.A., a small group of Independent experimenters have continued to build electrically powered road vehicles, and several com- mercial ventures to build and m.7--ket electric road vehicles, such as Sebring- Vanguard, were established throughout the years. Battery powered propulsion has been well suited to various off-the-highway vehicles such as industrial fork lift trucks, golf carts and underground mining machinery, Lower maintenance costs and longevity are well documented benefits of the electrics, but their higher initial cost and lower overall performance have been drawbacks.

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