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Energy supply and distribution

Energy supply and distribution. Lin Zhong ELEC518, Spring 2011. Outline. Battery technologies Battery properties Fuel cell batteries Smart battery interface Power distribution. Brief history of batteries. Battery density increases about 10% annually

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Energy supply and distribution

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  1. Energy supply and distribution Lin Zhong ELEC518, Spring 2011

  2. Outline • Battery technologies • Battery properties • Fuel cell batteries • Smart battery interface • Power distribution

  3. Brief history of batteries • Battery density increases about 10% annually • 1950 Nickel Cadmium (NiCd) (banned in EU from 2006) • 1990 Nickel-metal Hydride (NiMH) • 1991 Lithium Ion (Li-ion) • 1999 Li-ion Polymer • Most devices have battery capacity within 1500mAh, typically slightly more than 1000mAh (@3-5V) • Nokia 9500 communicator: 1300mAh (@3-5V) Li-ion Polymer, 172 grams • Dell Latitude D610: 4700mAh (@11V) Li-ion, 2300 grams

  4. Energy density

  5. Cell structures

  6. Battery properties I Volumetric energy density for Li-Ion cells Powers, 1994

  7. Battery properties I (Contd.) Starner, 2003 (IEEE Pervasive)

  8. Battery properties II Voltage drop Casas & Casas, 2005 (Energizer batteries)

  9. Battery properties III Rate dependent Lithium-Ion battery Rao et al 2003

  10. Battery properties IV Temperature dependent Lithium-Ion battery Rao et al 2003

  11. Battery properties V Capacity loss (aging) Lithium-Ion battery Rao et al 2003

  12. Battery properties VI Recovery effect Martin, 1999

  13. Wireless charging The Latitude Z on wireless charging station, and wireless dock adapter on the right. (Credit: Erica Ogg/CNET)

  14. Wireless charging (Contd.) Palm Pre™ Touchstone™ Charging Dock

  15. Fuel cell for portable power • Proton exchange membrane (PEMFC) • Direct methanol (DMFC) • Low operating temperature (60-80 degree C) Ellis, Spakovsky & Nelson, 2001

  16. Fuel cell system Fuel cell system schematics 40-50% efficiency Ellis, Spakovsky & Nelson, 2001

  17. A hot case: 3-Watt Nokia 3120 Every One Watt increases surface temperature by about 13 deg C Phone case temperature will be 40 deg C higher.

  18. Applications • Portable energy storage (charger) • Refillable fuel cell $39---3300mAh fuelcellstore.com Motorola: under development

  19. Hitachi prototypes (2005)

  20. Toshiba prototypes (2005)

  21. Medis (2008) • Available through BestBuy

  22. Supercapacitors/Ultracapacitors • Fast charging • More cycles • High power density • Low energy density http://news.cnet.com/8301-11128_3-10363496-54.html

  23. Battery management • Accurate battery capacity monitoring • TI BQ2023 • Coulomb (Charge) counting-based monitoring • Single-wire advanced battery monitor IC

  24. Battery gas (fuel) gauge SDQ single-wire serial communications interface

  25. Smart battery interface • Single wire • Embedded clock

  26. Smart battery interface (Contd.) • Two-wire SMBus system • One wire for clock • TI BQ2040

  27. Windows Mobile battery API • Battery is treated as a peripheral device • Battery driver DWORD GetSystemPowerStatusEx2 (PSYSTEM_POWER_STATUS_EX2 pSystemPowerStatusEx2, DWORD dwLen, BOOL fUpdate);

  28. Discussion • Why is battery gas gauge difficult?

  29. Power distribution -20% (Cooling) 100% -5% Generation Source Transmission Data Center ~55% - Electrical Pwr ~30% - Processing Pwr -10% DC-DC -10% AC/DC Application Load; Processor, DSP, Memory Graphics Line Card Shelf/Rack System Evaldo Miranda & Laurence McGarry, Analog Devices

  30. Power distribution VR: voltage regulator

  31. Voltage regulator (DC-DC) • Maintain a constant voltage output

  32. Linear regulator • Output voltage • Dropout • Output current limit • Input voltage range

  33. Linear regulator (Contd.) • Efficiency Power waste ≈ (Vin-Vout) * Iload

  34. Regulator network • A regulator achieves best efficiency over a narrow range of output current

  35. Decoupling capacitors Bypass capacitors AC2DC VR L=dI/dt A B

  36. Impact on power measurement • Low-pass filtering effect Quming Zhou, Lin Zhong, and Kartik Mohanram, "Power signal processing:  A new perspective for power analysis and optimization," in Proc. ACM/IEEE Int. Symp. Low Power Electronics and Design (ISLPED), August 2007.

  37. http://batteryuniversity.com/

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