Increasing Electrical Damping in Energy Harnessing Transducers

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Increasing Electrical Damping in Energy Harnessing Transducers

  1. 1. Visit www.seminarlinks.blogspot.in to Download
  2. 2. Objectives 1. Introduction 2. Limitation of the present system 3. Suggestion that is offered 4. Transducers 5. Ambient energy 6. Electrical damping 7. Electrostastic transducers 8. Electromagnetic transducers 9. Piezoelectric transducers 10. Conclusions
  3. 3. Introduction  Focuses on the need for energy investment.  Boosting of output power by increasing damping energy.  Transducers included : electrostatic, electromagnetic, piezoelectric.
  4. 4. Limitations of the present system  Wireless micro sensors use small batteries to meet the power demands.  Miniaturized batteries unfortunately exhaust easily.  This limits the deployment of the micro sensor devices to few niche markets.  Increase in the budget.
  5. 5. Suggestion that is offered  Harnessing ambient energy .  Increasing the electrical damping force against which the transducers work.  Investing energy to increase the damping.
  6. 6. Transducers  Converts one form of energy to another.  Can be any conversion.  Used for measuring purposes.
  7. 7. Ambient energy  Also known as Energy Scavenging or Power Harvesting.  Process of obtaining energy from environment.  Classified as Energy reservoir , Power distribution or Power scavenging methods.  Enable battery independent wireless or portable systems .
  8. 8. Electrical damping
  9. 9. Inferences from the above circuit
  10. 10. Output power for low and high k values
  11. 11. CONTD…  Investing voltage in capacitor or current in inductor raises damping force.  Rise in voltage or current → rise in battery investment → square of voltage or current.  EF - EINV rises with VINV and I INV.
  12. 12. ELECTROMAGNETIC TRANSDUCERS
  13. 13. Coupling electromagnetic energy with parallel resonant tank
  14. 14. INFERENCES FROM CIRCUIT
  15. 15. Proposed system  Removed capacitors and replaced diodes.  Synchronous on chip MOSFETs.
  16. 16. WORKING  SEPD and SEND close during positive half cycle.  Energizes LS through Lp. SEPD and SPD close and SEND opens : negative half cycle.  Depletion of Ls energy to VBAT.  Current reverses ; invests into LS.  SEND closes and SPD opens.  Current increases below IINV by ΔiL.  Invested into VBAT  Cycle concludes . Final energy = 0.5LS(IINV +ΔiL)2 ΔiL ≈ 2VEMF.S(PK)/ωoLs
  17. 17. PERFORMANCE  At 0.06, Po increases iff IINV<400µA.  AT 0.03, Po peaks at 750µA. Kc << 1,conduction losses increases. Investment below threshold holds no good.
  18. 18. ELECTROSTATIC TRANSDUCERS
  19. 19. BASIC PRINCIPLE CVAR precharged by energy investment. Used to establish electrostatic attraction and opposes physical movement. Vibrations produces energy ; FDE is higher. FDE increases as square of vc ;also EC. Implies higher voltage induces more damping More damping ⇒ more output power. vc close to VMAX ⇒ more energy generated.
  20. 20. TYPES OF CONNECTIONS PERMANENT CONNECTION : Constraining CVAR voltage with Li battery : no additional capacitor needed.  disadvantage : VBAT not the max voltage sustained.  CCLAMP used to overcome the above difficulty.  Tx invest energy EINV from VBAT : precharging both capacitors.  Discharges after harvesting cycle.  CCLAMP >> CVAR, more conduction losses. ASYNCHRONOUS CONNECTION :  TX charges CVAR near VMAX before the other..  Higher than CCLAMP high voltage.  Interface circuit transfers energy from CCLAMP to VBAT.  Less energy transfer.  Diode dissipates power.
  21. 21. PROPOSED CONNECTION  TX charges CVAR to CCLAMP initial voltage.  S3 closed ; energy extracted into CCLAMP.  TX discharges CVAR to VBAT  De energizing less often  S3 dissipates less power.  Cvar remains near to VMAX.
  22. 22. PERFORMANCE
  23. 23. PIEZO ELECTRIC TRANSDUCERS  Charge generated in response to mechanical vibration.  OC current energizes and de energizes CP.  CP charged to VBAT + 2VD.  Excess flows through rectifier.  Unloaded : CP charged to 2VOC CP .  Loaded : excess charge to VBAT . BATTERY COUPLED DAMPING EH =2(QOC – 2VBAT CP )VBAT
  24. 24. RECYCLING INDUCTOR:  LRE and SRE included. CP ‘s energy recycled in the opposite direction. Positive half cycle : CP charged to VBAT Negative half cycle: SRE closes ; LRE de energizes CP . Collects all of QOC . SRE dissipates energy. EH = 2QOC VBAT =4CP VOC VBAT
  25. 25. BATTERY DECOUPLED DAMPING  Decouple VBAT : increased damping energy.  Vibrations charge CP to max value.  Discharges through LH and DN in positive cycle.  LH and DI negative cycle.  De energizes to VBAT .  Cp energizes with 2VOC in half cycle.  Twice as EH ’ and 4 times EH ’’ .
  26. 26. PROPOSED SYSTEM  Energy gained reinvested to other half.  Precharged CP to –2VOC .  Voltage increased to 4VOC .  Energy increases with square of voltage. EH ’’’ = 0.5CP (-4VOC)2
  27. 27. PERFORMANCE  Increasing investment diminishes PO. More energy transfer through switches.  Conduction losses increases. Enlarged FET’s balances losses ; raises PO .  72000µm raised 56% PO .
  28. 28. CONCLUSION  Shows that investing energy increases output power.  Coupling factor of transducers low ⇒low power.  Invest energy to raise electrical damping.  Transducers draw more energy.  Limitation in increasing output power.
  29. 29. References  G. Chen et al., “Circuit design advances for wireless sensing applications,” Proc. IEEE, vol. 98, no. 11, pp. 1808–1827, Nov. 2010.  S. D. Senturia, “Energy-conserving transducers,” in Microsystem DesignNew York: Springer-Verlag, 2001, pp. 125–145  L. Xun and S. Y. Hui, “Simulation study and experimental verification of a universal contactless battery charging platform with localized charging features,” IEEE Trans. Power Electron., vol. 22, no. 6, pp. 2202–2210, Nov. 2007
  30. 30.  R. J. M. Vullers et al., “Micropower energy harvesting,” Solid State Electron., vol. 53, no. 7, pp. 684–693, Jul. 2009.  M. Kiani and M. Ghovanloo, “An RFID-based closed- loop wireless power transmission system for biomedical applications,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 57, no. 4, pp. 260–264, Apr. 2010.  C. Chih-Jung et al., “A study of loosely coupled coils for wireless power transfer,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 57, no. 7, pp. 536–540, Jul. 2010.
  31. 31. THANK YOU Visit www.seminarlinks.blogspot.in to Download

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