Final Presentation - 23-03-10
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Transcript of Final Presentation - 23-03-10
PINNA LUIGIPH.D COURSE IN NANOTECHNOLOGY
MARCH 2010
VIBRATION-BASED ENERGY SCAVENGING
FOR 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 µJ 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 µJ 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 amplitudeω = vibration frequency
Inertia of the mass
MechanicalDamping
Mechanicalstiffness
Capacitance between
electrodes
Fin = main sinωt
σ
i
tKmaKF ininin ωσ sin==
nVVt
Yad
p
p =
−=
231σ
Mechanical -> Electrical Coupling
a = 1
a = 2
tp
ElectromechanicalConversion
Block
d31 = piezoelectric constantYp = piezoelectric material Young’s modulustp = thickness of the piezoelectric material
Input Stress
σ
Electromechanical model of the PBG
i
tKmaKF ininin ωσ sin==
+=
+=
331313
3311111
ETdD
EdTsST
E
ε
Constitutive equations for a linear piezoelectric material
Electromechanical model of the PBG
( ) SASYdawli ipe == 31
Electrical -> Mechanical coupling
nVVt
Yad
p
p =
−=
231σ
Mechanical -> Electrical Coupling
ElectromechanicalConversion
Block
d31 = piezoelectric constantYp = piezoelectric material Young’s modulustp = thickness of the piezoelectric materialw = width of the piezoelectric materialle = length of the electrode
Input Stress
σ
i
tKmaKF ininin ωσ sin==
+=
+=
331313
3311111
ETdD
EdTsST
E
ε
Constitutive equations for a linear piezoelectric material
( ) SASYdawli ipe == 31
Electrical -> Mechanical coupling
nVVt
Yad
p
p =
−=
231σ
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 ωσ 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
≈⇒<<
+=++
=
=−− ∫∫
)(
)()()(
01)(1
SWSW on
SW off
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 µm• Lp = 0.5 µm• Wn = 1 µm• Ln = 0.5 µm
Vrec
Vrec
SPICE analysis
Vripple = 0.5%
idriv = 850 µA (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 µA
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 µm•Lp = 2.2 µm•Wn = 0.5 µm (minimum width)•Ln = 2.2 µm
Self-Powered DC-DC voltage regulator
idriv ≅ 90 µA (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 PRloadPMechRload
VP
iVP
SnAP
RloadRload
PBGout
ini
Mech
2
,
=
⋅=
⋅= σ3.3 V DC
SPICE analysis resultsSTRAIN RATE, dS1/dt
STRESS
PIEZOCERAMIC
PIEZOCERAMIC
1
2
3
S1σ1
S1σ1
Efficiency of the voltage
regulator
Pout,PBG PRload
η = 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 Ω) of VFNDM50
Wtot = 3600µm @ 1mA @
|Vgs|=3.3V
Floating poly Diode (FID50U)
Vd @Id=1mA
Wanode = 21 µm @ m=1
->Rd=653Ω @ m=80
n-channel VDMOS (VFNDM50)
• Wchannel=40 µm
• Ron=Vds/Ids @ Vgs=3.3V
@ Ids=1mA->Ron=16 Ω @ Wtot = 750 µm
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
η = 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 μF capacitive load
• PBG1 connected to the Test Board
• Vibrations @ ~33 Hz
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
ConclusionsThe developed SPICE model of the PBG has shown the
importance to have an equivalent model in SPICE of the vibration-based transducerBetter estimation of the behavior of the system with respect to
the use of simple equivalent PBG models
The developed SPICE model of the PBG has shown the importance to have an equivalent model in SPICE of the vibration-based transducerBetter estimation of the behavior of the system with
respect to the use of simple equivalent PBG modelsAnalysis of the reciprocal interaction among
mechanical and electrical parametersEvaluation of the current, voltage and power
generated by a PBG when connected to the power management systemOptimization of the power management system
Conclusions
Power Management System architectures
Conclusions
PROPOSED ARCHITECTURE
Proposed Power Management System architecture Innovative and Simple approach PBG + Semi-active bridge rectifier +Voltage regulator
Self-powered (SPICE version) Validated the well working of the prototype Test Chip and Test
board Efficiency of the system could be improved
• Optimization of the Voltage Level Shifter circuit• Design of the integrated comparator
• Should be designed to work in the sub-threshold region
• Low power and current consumption (order nW and nA )
• Solve the problem of the generation of a stable voltage reference in input to the driver comparator
Conclusions
Further experimental tests are necessary to validate and optimize the SPICE model of the PBG
• Inclusion of various losses - dielectric, piezoelectric and viscoelastic - might be necessary
Careful study is needed to be conducted • Set up of the experiments
Conclusions