Vehicle Design Strategies-PNGV Goals
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Vehicle Design Strategies to Meet and Exceed PNGV Goals Timothy C. Moore and Amory B. Lovins The Hypercar Center Rocky Mountain Institute SAE Paper No. 951906, reprinted (with minor corrections) with the kind permission of the Society of Automo- tive Engineers, publisher and copyright-holder, as published for the SAE Future Transportation Technology Conference, Costa Mesa, CA, 4 August 1995. Technical Inquiries: Timothy Moore at The Hypercar Center, Rocky Mountain Institute, 1739 Snowmass Creek Road, Snowmass, CO 81654-9199, (970) 927-3807, fax (970) 927-4510, Internet ‘[email protected]’ or ‘[email protected]’, PictureTel available on request. Ordering Information: Additional copies can be obtained for $10 from Rocky Mountain Institute, 1739 Snowmass Creek Road, Snowmass, CO 81654-9199, (970) 927-3851, fax (970) 927-3420, Internet ‘or- [email protected]’, or for $10 ($5 to SAE members) from SAE, 400 Commonwealth Drive, Warrendale, PA 15096- 0001, (412) 776-4841, fax (412) 776-1615. This paper is also included in SAE Special Publication No. 1105. CONTENTS: ABSTRACT.........................................................................................................................1 INTRODUCTION...............................................................................................................1 NOMENCLATURE............................................................................................................2 PERFORMANCE AND SAFETY CRITERIA...................................................................2 PNGV Design Criteria....................................................................................................2 Design Criteria for This Analysis...................................................................................2 PROPULSION SYSTEMS TECHNOLOGIES...................................................................3 Conventional, Battery-Electric, or Hybrid-Electric Drive?..........................................3 BODY-IN-WHITE STRUCTURE: MATERIALS AND MASS REDUCTION..............4 Steel.................................................................................................................................5 Aluminum........................................................................................................................5 Fiber Reinforced Composites.........................................................................................6 VEHICLE PLATFORM DESIGN, ROAD LOADS, AND ACCESSORY LOADS.........7 Achieving Balance.........................................................................................................7 Vehicle Configurations...................................................................................................7 Decoupling of Mass and Size.........................................................................................7 Mass Contribution to Peak Power Requirements...........................................................8 Mass Reduction...............................................................................................................8 Mass Decompounding....................................................................................................8 Rolling Resistance and Tires..........................................................................................9 Aerodynamics: Frontal Area........................................................................................10 Aerodynamics: Drag Coefficient.................................................................................10 Glazing and Accessory Loads.....................................................................................11 CRASHWORTHINESS, SAFETY, AND VEHICLE DYNAMICS................................12 Design and Materials for Safety..................................................................................12 Frontal Impacts.............................................................................................................12 Side Impacts..................................................................................................................13 General Safety Feature Considerations.......................................................................14 Mass Distribution and Vehicle Dynamics....................................................................14 Suspension and Steering...............................................................................................15 Brakes...........................................................................................................................15 Wheels..........................................................................................................................16 OTHER PLATFORM DESIGN DETAILS......................................................................16 Interior Trim, Carpet, and Seats...................................................................................16 Lights, Electricals, Instrumentation, and Controls.......................................................16 DRIVESYSTEM................................................................................................................16 Hybrid Drivesystem Configuration and Design Trade-Offs.......................................16 Parallel Hybrid Drivesystems.......................................................................................17 Series Hybrid Drivesystems.........................................................................................17 Series Hybrid Design and Control Strategies...............................................................17 SERIES HYBRID CONTROL STRATEGY RECOMMENDATIONS..........................18 TRACTION MOTORS......................................................................................................19 Motor Controllers and Inverters...................................................................................20 LOAD LEVELING DEVICES.........................................................................................21 Advanced Batteries......................................................................................................21 Ultracapacitors.............................................................................................................22 Flywheels......................................................................................................................22 AUXILIARY POWER UNITS.........................................................................................23 Internal Combustion Engines........................................................................................24 Gas Turbines.................................................................................................................25 Stirling Engines.............................................................................................................25 Thermophotovoltaics....................................................................................................25 Fuel Cells.......................................................................................................................26 MODELING......................................................................................................................26 Vehicle Mass................................................................................................................27 Rolling Resistance.........................................................................................................27 Aerodynamic Drag.......................................................................................................27 Accessory Loads..........................................................................................................27 Series Hybrid Drivesystem...........................................................................................27 SIMPLEV Input Summary............................................................................................29 MASS BUDGETS FOR DESIGN SCENARIOS..............................................................30 ROAD LOADS FOR DESIGN SCENARIOS..................................................................32 PERFORMANCE FOR PNGV SCENARIO AND FORD TAURUS...............................33 FUEL ECONOMY SENSITIVITY TO SELECTED PARAMETERS............................34 SIMPLEV MODELING RESULTS..................................................................................35 CONCLUSIONS................................................................................................................40 ACKNOWLEDGMENTS.................................................................................................41 REFERENCES...................................................................................................................41 Vehicle Design Strategies to Meet and Exceed PNGV Goals Timothy C. Moore and Amory B. Lovins The Hypercar Center, Rocky Mountain Institute Snowmass, CO 81654 SAE Paper No. 951906, reprinted with the kind permission of the Society of Automotive Engineers, publisher and copyright-holder. ABSTRACT competitive mass production of marketable automobiles meeting or exceeding PNGV goals both feasible and desirable. A host of important and interactive factors contribute to Current PNGV goals include a body-in-white (BIW) mass the successful design of any production vehicle. However, the reduction of 50%. This is reasonable given relatively conserva- combination of hybrid-electric drive and low-drag platform tive assumptions