Final Presentation - 23-03-10

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  • PINNA LUIGIPH.D COURSE IN NANOTECHNOLOGY

    MARCH 2010

    VIBRATION-BASED ENERGY SCAVENGINGFOR POWER AUTONOMOUS WIRELESS

    SENSOR SYSTEMS

    UNIVERSITY OF GENOAPH.D. SCHOOL IN

    SCIENCE AND TECHNOLOGY FOR INFORMATION ANDKNOWLEDGE

  • Motivations

  • Motivations

  • Motivations

    CNW

  • Motivations

    System on-chip

  • System on-chip

    Power autonomous Wireless Sensor System

  • MotivationsThe battery, is the most limiting factor for the sizereduction and life time of Wireless Sensor Systems

    e.g. MICAz, AA batteries occupy the 90% of the device dimensions

    System on-chip Tiny Fully integrated Pervasive Non-invasive Power-autonomous Communication-

    autonomous Multifunctional and

    high sensitive sensor arrays-based

  • PhD research Focus On

  • Solar

    Thermoelectric

    Electromagnetic (RF)

    Mechanical Vibrations

    Ambient energy sources

  • Solar

    Thermoelectric

    Electromagnetic (RF)

    Mechanical Vibrations

    Ambient energy sources

  • Solar

    Thermoelectric

    Electromagnetic (RF)

    Mechanical Vibrations

    Available in many environments

    e.g. household goods, industrial machineries, automobiles, buildings,

    Power densities near to solar cells for long period of operation (in terms of years)

    Ambient energy sources

  • Electrostatic Relative motion between two conductors separated by a dielectric

    Pros Suitable to be easily miniaturized with micro-fabrication technologies

    Cons The capacitor must be pre-charged at its maximum capacitance point (electrostatic generators are

    basically variable capacitors) Low output current High output impedance Relatively high AC output voltage (till 220 V)

    Electromagnetic Relative motion between a fixed coil and a moving magnet or vice versa

    Pros High output power density High output current

    Cons Difficult to miniaturize due to the low quality magnets available and low resistance coils obtainable Relatively low AC output voltage (< 1 V)

    Piezoelectric Bender Generators Charge generation due to mechanical strain of the piezoelectric material

    Pros High quality thin layers of piezoceramic materials High output power density High AC output voltage

    Cons Low output current High output impedance

    Vibration-based generators

  • Electrostatic Relative motion between two conductors separated by a dielectric

    Pros Suitable to be easily miniaturized with micro-fabrication technologies

    Cons The capacitor must be pre-charged at its maximum capacitance point (electrostatic generators are

    basically variable capacitors) Low output current High output impedance Relatively high AC output voltage (till 220 V)

    Electromagnetic Relative motion between a fixed coil and a moving magnet or vice versa

    Pros High output power density High output current

    Cons Difficult to miniaturize due to the low quality magnets available and low resistance coils obtainable Relatively low AC output voltage (< 1 V)

    Piezoelectric Bender Generators Charge generation due to mechanical strain of the piezoelectric material

    Pros High quality thin layers of piezoelectric materials High output power density High AC output voltage

    Cons Low output current High output impedance

    Vibration-based generators

  • Ph.D research goal

    The objective of the research activity has been to pursuethe design and development of a power-aware, integratedand self-powered vibration-based Power ManagementSystem for Piezoelectric Bender Generators (PBG)

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of a prototype of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of the prototype of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • L. Pinna, M. Valle, G. M. Bo, Experimental results of Piezoelectric Bender Generators for the energy supply of Smart Wireless Sensors, Proceedings of AISEM2008 The XIII annual conference of Associazione Italiana Sensori E Microsistemi, Rome, 19th -21st of February 2008

    Hypothesis: about the feasibility of powering a commercial WTPMS with a PBG every 5 minutes

    Set up

    ATA6285/6286 WTPMS ATMEL Supply: 2V to 3.6V 20 kbps @ 64 bits @ 315 MHz 5.05 msec @ 1 msec (Estimated measurement

    requested time) 17.4mW Power consumption (Estimated)

    Experimental tests @ different distance of the PBG from the

    wheel center (9cm,16cm) @ different car speed and the PBG

    (50km/h,80km/h) @ different PBG thickness (0.32mm,0.66mm)

    Feasibility study: Wireless Tire Pressure Measurement System (WTPMS) powered by PBG

  • Feasibility study: Wireless Tire Pressure Measurement System (WTPMS) powered by PBG

    Some experimental results Est = 518 J Energy storage in 5 minutes @ Vcap = 2.2 V

    (measured voltage)

  • Feasibility study: Wireless Tire Pressure Measurement System (WTPMS) powered by PBG

    Some experimental results Est = 518 J Energy storage in 5 minutes @ Vcap = 2.2 V

    (measured voltage)

    P = 103 mW @ 5.o5 msec

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of the prototype of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • Necessary an equivalent SPICE source which models the behavior of the PBG

    Based on an electromechanical model which takes into account geometrical and physical parameters

    The reciprocal interaction between PBG and scavengingsystem in terms of stress, strain rate, mechanical andelectrical powers at various loads can be studied andinvestigated

    SPICE model of the PBG

  • Electromechanical model of the PBG

    ElectromechanicalConversion

    Block

    Strain ratedS1/dt

    Input Stress

    Output Voltage

    S Roundy and P K Wright, A piezoelectric vibration based generator for wireless electronics, Smart Materials Structures, Vol. 13, pp. 1131-1142, 2004

    Stress developed as result of the input vibrations

    K = geometrical constant [m-2]m = inertial massain = acceleration amplitude = vibration frequency

    Inertia of the mass

    MechanicalDamping

    Mechanicalstiffness

    Capacitance between

    electrodes

    Fin = main sint

    i

    tKmaKF ininin sin==

  • nVVt

    Yad

    p

    p =

    =

    231

    Mechanical -> Electrical Coupling

    a = 1

    a = 2

    tp

    ElectromechanicalConversion

    Block

    d31 = piezoelectric constantYp = piezoelectric material Youngs modulustp = thickness of the piezoelectric material

    Input Stress

    Electromechanical model of the PBG

    i

    tKmaKF ininin sin==

    +=

    +=

    331313

    3311111

    ETdD

    EdTsST

    E

    Constitutive equations for a linear piezoelectric material

  • Electromechanical model of the PBG

    ( ) SASYdawli ipe == 31Electrical -> Mechanical coupling

    nVVt

    Yad

    p

    p =

    =

    231

    Mechanical -> Electrical Coupling

    ElectromechanicalConversion

    Block

    d31 = piezoelectric constantYp = piezoelectric material Youngs modulustp = thickness of the piezoelectric materialw = width of the piezoelectric materialle = length of the electrode

    Input Stress

    i

    tKmaKF ininin sin==

    +=

    +=

    331313

    3311111

    ETdD

    EdTsST

    E

    Constitutive equations for a linear piezoelectric material

  • ( ) SASYdawli ipe == 31Electrical -> Mechanical coupling

    nVVt

    Yad

    p

    p =

    =

    231

    Mechanical -> Electrical Coupling

    SPICE model of the PBG

    Luigi Pinna, Ravinder S. Dahiya, Maurizio Valle, SPICE model for piezoelectric bender generators, ICECS 2009, The 16th IEEE International Conference on Electronics, Circuits, and Systems, Hammamet, Tunisia, December 13th 16th, pp. 587-590, 2009.

    Input StresstKmaKF ininin sin==

  • Simulation results: MATLAB vs SPICERoundy et al.

    Optimized custom PBGVol. = 1cm3 (Device volume)f = 120 Hz (Vibration frequency)a = 2.5 m/s2 (Acceleration amplitude)

  • Simulation results: MATLAB vs SPICE

    Roundy et al.

    Roundy et al.

    Optimized custom PBGVol. = 1cm3 (Device volume)f = 120 Hz (Vibration frequency)a = 2.5 m/s2 (Acceleration amplitude)

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of the prototype of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • Power Management System

  • Power Management System

  • AC-DC full-wave bridge rectifierActive vs Diode Bridge Rectifier

    Advantages

    Lower Power Consumption

    Lower voltage drop across active device than diode (0.7 V)

    Advantage for low power systems

    Design flexibility

    Drawbacks

    Control circuits for active devices

    Circuit complexity (fully active)

  • The use of only two active devices in place of two of the fourdiodes aimed to develop a simple circuit

    Semi-Active Bridge Rectifier

    CONTROLCIRCUIT

  • The use of only two active devices in place of two of the fourdiodes aimed to develop a simple circuit

    PBG generates high output voltageNecessary a HV process technology up to 50 V

    Semi-Active Bridge Rectifier

    CONTROLCIRCUIT

  • The use of only two active devices in place of two of the fourdiodes aimed to develop a simple circuit

    PBG generates high output voltageNecessary a HV process technology up to 50 V

    Self-starting thanks to the intrinsic VDMOS diodes (bd1, bd2)

    Semi-Active Bridge Rectifier

    CONTROLCIRCUIT

  • Semi-Active Bridge Rectifier

    The use of only two active devices in place of two of the fourdiodes aimed to develop a simple circuit

    PBG generates high output voltageNecessary a HV process technology up to 50 V

    Self-starting thanks to the intrinsic VDMOS diodes (bd1, bd2)

  • Power Management System

  • DC-DC converterDC-DC switching converter

    An active device - controlled by a controller circuit -transforms the input rectified voltage to a square-wave with adjustable duty-cycle

    A passive filter - with inductor and capacitor - extracts the average of the square wave signal, which corresponds to the DC output voltage value

    Pros High efficiency Step-up and step-down Flexibility of the control

    circuits design Smart switching control circuits

    Cons Complex control circuits Step-down Buck Converter Generates a Vout < Vin

    SW

  • Steady-state: switch closedDC-DC converter

    =

    ==

    ontoutinonL

    LoutinL

    dtVVL

    I

    dtdiLVVV

    )(1,

    =

    ==

    offtoutonL

    LoutL

    dtVL

    I

    dtdiLVV

    1,

    Steady-state: switch opened

    SW on

    SW off

  • DC-DC converter

    inout

    loadin

    inout

    offon

    on

    PPDIIDVV

    D

    DutyCycleTT

    TD

    ===

    =+

    =

    )1,0(

    inoutinripple

    rippleinrippleinoffon

    onout

    tout

    toutin

    DVtVDVv

    tvDVtvVtt

    ttV

    dtVL

    dtVVL

    offon

  • Power Management System

  • DC-DC converter controller

    DC-DC CONVERTERCONTROL

    BLOCK

  • DC-DC converter controller

    VOLTAGELEVEL

    SHIFTER

    DRIVER

    Vrec

  • DRIVER

    DC-DC converter controllerVrec

  • DC-DC voltage regulatorVrec

    If Vout < Vref Vctrl -> Low Vrec-Vctrlsw 3.3V

    If Vout > Vref Vctrl -> High Vrec-Vctrlsw = 0

    SW3 -> ON

    SW3 -> OFF

  • SPICE analysisSPICE ideal AC voltage source

    Reference Inverter Wp = 2.25 m Lp = 0.5 m Wn = 1 m Ln = 0.5 m

    Vrec

  • Vrec

    SPICE analysis

    Vripple = 0.5%

  • idriv = 850 A (Current consumption)

    SPICE indipendent AC voltage source

    Vrec

    SPICE analysis

  • DC-DC voltage regulator with PBG as source

  • DC-DC voltage regulator with PBG as source

    Roundy et al.

    Optimized custom PBGVol. = 1cm3 (Device volume)f = 120 Hz (Vibration frequency)a = 2.5 m/s2 (Acceleration amplitude)

  • DC-DC voltage regulator with PBG as sourceiPBG ~ 200 A

    Roundy et al.

    Optimized custom PBGVol. = 1cm3 (Device volume)f = 120 Hz (Vibration frequency)a = 2.5 m/s2 (Acceleration amplitude)

    3.3 V

  • DC-DC voltage regulator with PBG as source

    CURRENT-AWARE OPTIMIZEDReference Inverter

    Wp = 1.25 mLp = 2.2 mWn = 0.5 m (minimum width)Ln = 2.2 m

  • Self-Powered DC-DC voltage regulator

    idriv 90 A (Current consumption)

  • SPICE analysis results

    Luigi Pinna, Ravinder S. Dahiya, Fabrizio De Nisi, Maurizio Valle, Analysis of Self-Powered Vibration-Based Energy Scavenging System, ISIE 2010, The IEEE International Symposium on Industrial Electronics, Bari, Italy, July 4th 7th, 2010, (accepted)

    Pout,PBG PRloadPMechRloadVP

    iVP

    SnAP

    RloadRload

    PBGout

    ini

    Mech

    2

    ,

    =

    =

    = 3.3 V DC

  • SPICE analysis resultsSTRAIN RATE, dS1/dt

    STRESS

    PIEZOCERAMIC

    PIEZOCERAMIC

    1

    2

    3

    S11

    S11

  • Efficiency of the voltage

    regulator

    Pout,PBG PRload

    = PRload / Pout,PBG

    SPICE analysis resultsPBG OUTPUT CURRENT

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of the prototype of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • On ASIC -> Only the key components semi-active bridge and buck converter switching part

    On PCB -> LC filter and switches control circuits Necessary a design flexibility for the experimental tests Design corrections could be needed Errors can be easily found and corrected

    ASIC and test PCB design

  • D1

    D2

    SW1

    D3

    SW2

    SW3

    1.465 mm

    1.45

    78 m

    mASIC design (AMIS I3T50u technology)

    TEST CHIP CORE

    ESD PROTECTIONS p-channel VDMOS (LFPDM50)

    Dimensioned to have the same Ron

    (i.e. 16 ) of VFNDM50

    Wtot = 3600m @ 1mA @

    |Vgs|=3.3V

    Floating poly Diode (FID50U)

    Vd @Id=1mA

    Wanode = 21 m @ m=1

    ->Rd=653@ m=80

    n-channel VDMOS (VFNDM50)

    Wchannel=40 m

    Ron=Vds/Ids @ Vgs=3.3V

    @ Ids=1mA->Ron=16 @ Wtot = 750 m

  • Ref: PBG T226-H4-303XVoc = 36Vppf = 400 HzPout = 7.2 mWrms

    EXTERNAL SUPPLY

    Test PCB design and validation Vctrlsw

    Vrec

    Vout

  • Test PCB design and validation

  • START UP TEST RECTIFIER SWITCHES TEST

    VO1

    AC1 G1

    Test PCB design and validation AC1 VO1

    VO1

    VO1

    G1

  • TESTCHIP

    OUTPUT VOLTAGE LOAD POWER

    Test PCB design and validation

    REGULATED VOLTAGE

  • INPUT POWER

    Test PCB design and validation

    TESTCHIP

    = Pin / Pout

  • Outline

    Feasibility study

    Development of the SPICE model of the Piezoelectric Bender Generator (PBG)

    Design and SPICE analysis of an integrated Power Management System with the SPICE model of the PBG

    Design, fabrication and experimental characterization of the Power Management System

    Experimental tests (preliminary)

    Conclusions

  • PBG1 63.5x31.8x.66 mm3

    Iron proof mass 220g ~32Hz resonance frequency

    Experimental tests (preliminary) PBG2

    31.8x3.2x.51 mm3 Iron proof mass 16g ~60Hz resonance

    frequency

    Shaker Tira TV50018 controlled by LabView

    AluminumSupports

  • Test 1 PBG1 Vout (Pout) vs.

    resistive load Vibrations @ ~33 Hz

    Experimental tests (preliminary)

    PRload

  • Experimental tests (preliminary)

    ~33 Hz

    Measured results:

    Problems related to the experimental Set-up

    Support structure

    Issues in the PBG

    Test 2 PBG1 Voc vs. Frequency

    of Vibrations

  • Test 3 PBG2 Voc vs. Frequency

    of Vibrations

    ~63 Hz

    Plastic Support

    Experimental tests (preliminary)

    ~32 Hz

  • Experimental tests (preliminary)Test 4: Rectified PBG output

    voltage PBG1 connected to the

    Test Board Vibrations @ ~33 Hz

  • Experimental tests (preliminary)Test 5: 3.3V regulated output

    voltage @ 1 F capacitive load

    PBG1 connected...