Master thesis presentation

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  • PM circuitHarvesterUltra low power opertion (uW)WATS system
  • Motivation  develop ultra low power sensors based on RF harvesting applications
  • Single-voltage..one arrow..table alignment
  • Trade offs: voltage regulation, synchronization with gate pulses, IC and discrete implementationHigh efficiency at low voltagesLow quiescent currentLow start-up voltage
  • Goal to find the input specs of the converter,The orientation of the RF harvesterFind the optimum load impedanceTwo sets of measurements to
  • Find optimum impedance Rectified power calculated from voltage measurements at different load resistances and distances from the transmitter.Goal to stay in the far field of the transmitter
  • Talk about input impedance of the diode; circuit diagram
  • Mention MPPT , expected input power to the PM circuit
  • Interpolating of the measurement results with the rectenna
  • PM and step-up converter
  • Output ripple voltage to reduce absorb the pulsating current and provide a smooth DC voltage to the converter.
  • Reverse saturation
  • Modeling and simulationModeling is the first order model, more complex inductor model
  • Talk about design of Rh and RL
  • LTC-3105
  • Master thesis presentation

    1. 1. Design of Power Management forAutonomous Wireless Monitoring Systems Master Thesis Presentation By Mayur SarodeSupervisorsTU/e : P.G.M Baltus, Dusan Milosevicimec/Holst center :Valer Pop
    2. 2. RF ENERGY HARVESTING RF-DC DC-DC Energy PM converter converter circuit Storage WATS Device RECTENNAHorn antenna DC-DC converter e.g. EOG tracking Microstrip patch based antenna , Ni-MH battery Eye system Diode based voltage doubler/ MSM/ELECTRICAL ENGINEERING
    3. 3. PROJECT OUTLINE MOTIVATION STATE-OF-THE-ART-PM* HARVESTER MEASUREMENTS PM CIRCUIT DESIGN PM CIRCUIT MEASUREMENTS RECOMMENDATIONS & CONCLUSIONS/ MSM/ELECTRICAL ENGINEERING *Power Management
    4. 4. MOTIVATION Architectural level: Multi supply  one-voltage domain system 9% 22% <1% 11% Radio <1% MCU PM 63μW PM 33μW 31% 39% (704 μW) ADC (151μW) Sensor&R-out 1% 78% PM 4% Vdd[V] Component Vdd [V] 3 Radio 1.2 2.3 MCU 1.2 2.7 ADC 1.2 3 Sensor & R-out 1.2 2.9 Battery 1.5/ MSM/ELECTRICAL ENGINEERING
    5. 5. STATE-OF-THE-ART OF PM Inductive vs Capacitive Converter topology PWM/PFM control strategy Size Efficiency Quiescent current Start-up voltageConverter specs Io(max),Vdc(max), fs and VbattOpen-loop resistor –emulation optimum control strategy/ MSM/ELECTRICAL ENGINEERING
    6. 6. STATE-OF-THE-ART PM ; IMEC/HOLST CENTER AC-DC buck-converter Inductive boost- converter Integrated capacitive DC-DC buck-boost converter SpecificationsSpecifications Specifications ▸ Input voltage 1~5VDC▸ Integrated AC-DC rectifier ▸ Adaptive MPP Control ▸ Output 10~300 μW▸ Input voltage 4~42VRMS ▸ Input voltage 1~2VDC ▸ Active Efficiency 80~87%▸ Output 10μW~5mW @ 3VDC ▸ Output 10μW~5mW & up to100% in direct charge▸ DC-DC Efficiency 87 - 94% ▸ End to end efficiency 60~70% TechnologyTechnology Technology ▸ Indoor Photo Voltaic▸ Vibrational Harvesting ▸ Indoor Photo Voltaic/ MSM/ELECTRICAL ENGINEERING
    7. 7. HARVESTER MEASUREMENTS; CHARACTERIZATION Harvester characterization  Power management specifications Parameter Value Unit Load No load, 10, 100, 10K, 100K Ω Rectenna Transmitted power 0 ,14 ,20 dBm Distance 1, 10, 20, 30, 50 cm Height 10 cm Orientation of Broadside /Vertical Rectenna Configuration Line of Sight, 45o ------ Rectifier Pinc -15 to 10 dBm  Find optimum load resistance/ MSM/ELECTRICAL ENGINEERING
    8. 8. HARVESTER MEASUREMENTS; RESULTS Parameter Value (EIRP: 100 mW) Unit Distance , R 1 10 20 30 50 cm Voltage , Vdc 1.2 0.6 0.3 0.2 0.12 mV Power, Pdc 1886 292.6 82 44 15 μW/ MSM/ELECTRICAL ENGINEERING
    9. 9. HARVESTER MEASUREMENTS; LOSSES Impedance matching losses ZL [Ω] Г ZS [Ω] Pinc [dBm] 2 Z L Z s*  35+40j Ω -15 0 2.5-55j Ω 35-40 j Ω 0.78 0 Z L Zs ZL - Load Impedance ZS – Source Impedance Rectenna efficiency  varies with available power/ MSM/ELECTRICAL ENGINEERING
    10. 10. HARVESTER MEASUREMENTS; CONCLUSIONS Rectenna A Rectenna B Input power to the converter < 500 μW Maximum input voltage to converter Vdc(max) ~ 0.4 V/ MSM/ELECTRICAL ENGINEERING
    11. 11. HARVESTER MEASUREMENTS; CONCLUSIONS Rectenna A Rectenna B Optimum load resistance varies with input power MPPT Approximated to a constant resistance (Rdc) for resistor emulation/ MSM/ELECTRICAL ENGINEERING
    12. 12. HARVESTER MEASUREMENTS;DERIVED SPECS. Parameter Value/ Functionality Unit Harvester Distance 0.2 – 0.6 m Rectenna Broadside in LOS* --- EIRP (max) 4 W, 50% Duty Cycled W Power management Circuit Input voltage Vdc 0.1 – 0.5 V Output voltage Vbatt Dependent on the battery (~1) V Input impedance Rdc 220 (reconfigurable) Ω Input power Pdc 1 - 500 μW Choice of a lower Rdc rectenna for resistor emulation  Choice of optimum PM circuit components *LOS- Line of Sight/ MSM/ELECTRICAL ENGINEERING
    13. 13. RF MEASUREMENTS; RECTENNA MODELING Friis model Rectifier measurements Parameter Value Unit PT 0.004 – 1.24 W GT 3.2 --- GR 3.1 --- λ 0.1244 m R 0.16 – 0.60 m PT(14dBm) ~ EIRP(80.64 mW) Based on Spline interpolation GT – Gain of the transmitter antenna GR – Gain of the receiver antenna Used for predicting autonomy λ – wavelength R - Distance from the transmitter EIRP - Effective Isotropic Radiated Power/ MSM/ELECTRICAL ENGINEERING
    14. 14. PM CIRCUIT DESIGN; DEFINING VARIABLES Harvester Terminology Variable Details Pin( Vin) Incident power(voltage)on the rectenna Pdc(Vdc) Input power(Input voltage) to the converter Pout Harvested Power ηconverter (Pout/Pdc) ηharvester (Pout/Pin)/ MSM/ELECTRICAL ENGINEERING 13
    15. 15. PM CIRCUIT DESIGN; SPECIFICATIONS Specifications Comments Unit Input impedance (Rdc) 220 (rectenna B) Ω Switching frequency, fs ----- kHz Input voltage, Vdc 0.1 - 1 V Output voltage, Vbatt 1 – 1.3 V Output current , Io(max) 1 mA Under Lock-out voltage ----- V Over lock-out voltage 1.3 V Input Ripple voltage 20% Vdc V output Ripple voltage ,ΔVo 1 mV/ MSM/ELECTRICAL ENGINEERING 14
    16. 16. PM CIRCUIT DESIGN; POWER STAGE ton D M1 Vdc RdcRECTENNA Ds RL Rin Cin Cout Ls Vin Vbatt Buck-Boost converter topology D Relating input/output voltage Vbatt Vdc 2 Ls RLTs On-time is calculated by 2 Ls ton f s Rdc/ MSM/ELECTRICAL ENGINEERING
    17. 17. PM CIRCUIT DESIGN; SELECTION OF M1 MOSFET power loss modeling MODELED MEASURED Choice dependant on Ron , tr , tf and Cgs of the MOSFET Verified with measurement results/ MSM/ELECTRICAL ENGINEERING 16
    18. 18. PM CIRCUIT DESIGN; SELECTION OF DsSchottky Diode forward voltage drop (Vf ) & Continuous Reverse Current( Is) Power losses at Vin 0.3 V (model)Verified with SPICE simulations/ MSM/ELECTRICAL ENGINEERING
    19. 19. PM CIRCUIT DESIGN; SELECTION OF Ls Conduction losses  DCR Trade off between inductor and diode conduction time 80 COnverter Efficiency [%] 70 60 50 900uW 180uW 100uW 40 1000 1500 1800 2200 220 68  Sweeping Ls for Rdc of 220Ω Inductance [μH]  Ls between 1 – 1.5mH is optimal/ MSM/ELECTRICAL ENGINEERING
    20. 20. PM CIRCUIT DESIGN; SELECTION OF Cin Cin  Reduce ripple voltage BEFORE AFTER Input capacitance was selected to be 10 μF(ESR 5 mΩ)/ MSM/ELECTRICAL ENGINEERING
    21. 21. PM CIRCUIT DESIGN; SELECTION OF COUT Cout  Charge battery when M1 is ON  Reduce output voltage ripple BEFORE AFTER  10μF low ESR selected/ MSM/ELECTRICAL ENGINEERING
    22. 22. PM CIRCUIT DESIGN; SELECTION OF fS  Selected for minimum converter loss  Optimum switching frequency increases with input power  PWM designed to reduce losses at low input power levels/ MSM/ELECTRICAL ENGINEERING
    23. 23. PM CIRCUIT DESIGN; OSCILLATOR DESIGN RC relaxation oscillator Low voltage comparator Vdd, Vss R2 R1 + - R3 D1 D2 Rh Rl Cosc Vdc Observed oscillation frequency at Vin :0.9 volt Duty cycle scales with step-up ratio/ MSM/ELECTRICAL ENGINEERING
    24. 24. PM CIRCUIT DESIGN; PROTECTION CIRUCIT Overcharging protection MAX9064 Under lock out protection MAX9063 Vbatt Vref Vdc Vref R10 - R7 Vin2 + R8 V1 Comp_U Comp_H V2 + DcVin1 - R6 R9 Vbatt Under-lock out  150 mV , Vdc Over-charging protection  1.3 V, Vbatt/ MSM/ELECTRICAL ENGINEERING
    25. 25. PM CIRCUIT DESIGN; LOSS ANALYSIS Modeling Converter losses at different power levels 250 Ploss [μW] Leakge Oscillator 200 Switch Diode Inductor 150 100 50 0 102 410.58 924 Diode major contributor Pin [μW] Leakage losses dominate at lower power levels/ MSM/ELECTRICAL ENGINEERING
    26. 26. PM CIRCUIT DESIGN; HARDWARE DEVELOPMENT PCB testing Layout  Expedition PCB tool* Schematic Design Capture tool* Circuit Verification on Breadboard/ MSM/ELECTRICAL ENGINEERING Mentor Graphics™
    27. 27. PM MEASUREMENTS/ MSM/ELECTRICAL ENGINEERING
    28. 28. PM MEASUREMENT; RESULTS Comparing Efficiency present & new generation PM Efficiency and output power for Vbatt 1.030 and 3.5 volt for 220 Ω rectenna Higher efficiency at lower rectenna voltages Vin/ MSM/ELECTRICAL ENGINEERING
    29. 29. PM MEASUREMENTS; WITH RECTENNA Comparing Autonomy 80 80 Efficiency [%] Efficiency [%] 10 cm 20 cm Present generation New generation 60 60 40 40 20 20 0 0 converter harvester converter harvester Measured efficiency at distance of 10 and 20 cm Increase in Autonomy of the harvester EIRP:100 mW/ MSM/ELECTRICAL ENGINEERING
    30. 30. PM MEASUREMENT; RESULTS Start-up voltage varies with battery voltage Start-up voltage of 210 mV Vin for Vbatt of 1.03 volt/ MSM/ELECTRICAL ENGINEERING
    31. 31. PM CIRCUIT ; OVERVIEW DCM, non synchronous buck-boost converter Over-Charging protection / under lockout protection Quiescent current of 27 μA Compact Design (2X2 cm 2 layer PCB board )/ MSM/ELECTRICAL ENGINEERING 30
    32. 32. RECOMMENDATIONS TPS22902 load switch, Ron 146 mΩ Quiescent Current Distribution Reducing Quiescent current at under-lockout voltage levels/ MSM/ELECTRICAL ENGINEERING
    33. 33. RECOMMENDATIONS  Higher ηconverter  PWM-PFM control strategy Higher ηconverter with adaptive PWM/ MSM/ELECTRICAL ENGINEERING
    34. 34. SUMMARY  1 V battery charging  lowest among commercial solutions ηconverter ~ 68% @ 900 mV available voltage Start-up voltage ~ 0.210 V Quiescent current ~~ 1 V IC solutions Protection circuits Reconfigurable for any arbitrary rectenna ( Rmpp 800Ω, 2.6 kΩ)/ MSM/ELECTRICAL ENGINEERING
    35. 35. THANKS …. Valer Pop , Prof. Peter Baltus , Dusan Milosevic My family and friends Audience present today/ MSM/ELECTRICAL ENGINEERING
    36. 36. CIRCUIT VERIFICATION/ MSM/ELECTRICAL ENGINEERING PAGE 35
    37. 37. WATS ARCHITECTURE Application electronics Sensor ADC Processor Radio Power transfer DC-DC converter Data transfer Energy storage RF-DC DC-DC converter converter - Battery - Super capacitor Rectenna PM Energy Harvester/ MSM/ELECTRICAL ENGINEERING PAGE 36
    38. 38. SCHEMATIC DESIGN/ MSM/ELECTRICAL ENGINEERING PAGE 37
    39. 39. LAYOUT/ MSM/ELECTRICAL ENGINEERING PAGE 38
    40. 40. PCB TESTING/ MSM/ELECTRICAL ENGINEERING PAGE 39

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