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Capacitive Electric Load Leveling Systems

Capacitive Electric Load Leveling Systems. Conceptual Design Review November 9, 2004 Erin Davis Fred Jessup Benton O’Neil. Presentation Outline. Customer Needs Key Research Issues Design Methods and Alternatives Deliverables Team Productivity. Customer Needs. Reduce vehicle weight

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Capacitive Electric Load Leveling Systems

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  1. Capacitive Electric Load Leveling Systems Conceptual Design Review November 9, 2004 Erin Davis Fred Jessup Benton O’Neil

  2. Presentation Outline • Customer Needs • Key Research Issues • Design Methods and Alternatives • Deliverables • Team Productivity

  3. Customer Needs • Reduce vehicle weight • Improve fuel efficiency • Achieve system payback period of one year • Demonstrate feasibility for tractor-trailers

  4. Key Research IssuesDetermined by Testing • Battery • Starting requires high-power density storage • Peak current ~600A • Large, heavy battery • Alternator • Supplies current regardless of engine load • Reduces engine efficiency during heavy loading • If controlled, could improve engine efficiency

  5. Possible Problems to be Addressed In Design • Battery Problem • High power requires heavy lead acid batteries • Non ideal charging and discharging • Alternator Problem • Supplies current regardless of engine mechanical load • Both Battery and Alternator Problem

  6. Design #1 – Addresses Battery • Converter controls discharging and charging of battery • Capacitor bank assists in starting engine and supplies some peak current due to low ESR • Battery current is normalized through control of DC/DC converter

  7. Scope Definition - Addressing Batteries • Pros • Ultracapacitors are ideal for supplying high current • Feasible as bolt-on system – no internal vehicle signals needed • Significant decrease in weight with reduced battery size • Improved battery charging algorithm • Increased battery life • Cons • No direct fuel efficiency improvement • Ideal charging algorithm is difficult to determine • Bi-directional DC/DC converters

  8. Design #2 – Addresses Alternator • Capacitor bank provides peak power through control of DC/DC converter • Battery starts engine with assistance of capacitors • Engine load due to alternator is normalized by switching algorithm

  9. Scope Definition – Addressing Alternator • Pros • Direct improvement in fuel efficiency • Reduction in battery power and size • Cons • Complex control system • Not feasible for bolt on system • Need for engine load monitoring • No guarantee of battery life improvement • High power DC/DC converter required

  10. Design #3 – Addresses Both • Combination of Design #1 and Design #2 • Battery current normalized by DC/DC converter • Engine load due to alternator normalized by switching algorithm

  11. Scope Definition - Addressing Both • Pros • Increase in battery life • Increase in fuel efficiency • Cons • Complex control • Large and complex system

  12. Initial Designs Decision Matrix

  13. Decision Matrix Results • Focus on Design #1 • Issues still needing to be address • Ideal charging algorithm • Specific DC/DC converter selection • Bi-directional versus unidirectional DC/DC converters • Buck, Boost, Buck-Boost • Capacitor bank sizing • Battery sizing • Physical • Power

  14. Design Focus ConclusionBattery: starting engine, weight issues • Basic Operation • Caps start engine • Small battery charges caps though converter • Alternator charges battery

  15. Modeling • Present system • Battery starting a 3.0L Lincoln LS engine • Discharging Capacitors • Starting engine • Charging Capacitors • Battery charging the capacitors through different converter topologies

  16. Modeling Objectives • Test different scenarios quickly, easily and safely • Compare design alternatives • Capacitors • Size, capacitance, and weight • Maximum and minimum voltage, charging time, and usable energy • Peak current magnitude, engine speed, motor torque • Converters • Control methods • Topologies • Verify the design prior to implementation

  17. Simulink Output

  18. Capacitor Selection • Using MathCAD • Parameters obtained from MAXWELL • Prices for set energy needed to start engine

  19. Converter Decision Matrix

  20. Preliminary Cost Analysis

  21. Remaining Design Choices • Battery • AH rating necessary to supply loads during engine off • Acceptable weight of battery • Control • Analog vs digital • Finalized converter topology

  22. Key Deliverables • As of Now • Stock System Models • Preliminary Cost Analysis • As of December 15, 2004 • Design Description Report • Detailed Parts List

  23. Foreseen Challenges • Design • DC/DC Converter • Control System Development • Installation • Engine Heat Signature • Packaging • Wiring, connections • Vibration • EMI Shielding

  24. Team Productivity • CELLS Team Webpage • Project Status Reports • Weekly meeting agendas / minutes • Extracurricular Activities

  25. Questions?

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