Energy Harvesting per Sensori e Microsistemi

Transcription

1 1 Energy Harvesting per Sensori e Microsistemi Vittorio Ferrari Dip. Ingegneria dell Informazione Università di Brescia ITALY vittorio.ferrari@ing.unibs.it Introduzione Energy Harvesting (EH) Esempi e applicazioni di EH in sensori Sensors and Electronic Instrumentation Laboratory Activity: Sensors and instrumentation systems Analog and digital electronic circuits and systems for: sensor interfacing sensor communication and networking measurement applications Sensors, MicroSystems and Electronic Interfaces: Piezoelectric transducers, acoustic-wave and resonant microsensors MEMS sensors and systems Contactless sensors Electronic interfaces for sensor signals Energy harvesting for autonomous sensors

2 Introduction Power Consumption from Internal Sources Wireless Sensor Nodes Passive RFID tags Functionalities&Performances Introduction Power Consumption from Internal Sources V4.0 Low Energy Ultra-low-power (ULP) Bluetooth variant Wireless Sensor Nodes Normic Semiconductor - Low-Consumption Nodes - Energy-Aware Sensor Nets Passive RFID tags - Active RFID - RFID-Sensors Ultra-small, ultra low-power, low-cost, high-performance sensor nodes and networks Functionalities&Performances

3 3 Introduction Power Consumption from Internal Sources V4.0 Low Energy Ultra-low-power (ULP) Bluetooth variant Wireless Sensor Nodes Normic Semiconductor - Low-Consumption Nodes - Energy-Aware Sensor Nets Importance of - Active RFID Energy Sources and - RFID-Sensors Power Management Passive RFID tags Functionalities&Performances General Architecture of a RF Sensor RF link environment/ system/ process sensor external readout unit information Information flow requires exchange of energy Assuming the external readout unit is energetically self-sufficient the sensor needs power supply

4 Power Supply Options: #1 RF link environment/ system/ process sensor external readout unit information Power supply internal to the sensor (on-board): Batteries (primary, rechargeable, thin-film) Supercapacitors Fuel cells Micro-combustors and -turbines Power Supply Options: # RF link environment/ system/ process sensor external readout unit information Power supplied by the external readout unit: Passive RFId devices (EPCglobal class 1 and ) Passive telemetric sensors Chipless RFId sensors 4

5 Power Supply Options: #3 RF link environment/ system/ process sensor external readout unit information Power extracted (harvested) from the surrounding ambient Energy from Ambient: the idea is not new Water- and windmills. 1770, A.L. Perrelet, self-winding watch. 1930, Jaeger-LeCoultre, Atmos clock powered by thermal fluctuations. Present, Motorola PVOT hand-crank phone. Present, Eolic generators. Present, FreePlay, wind-up radio. 1956, Zenith, battery-less ultrasound remote. 5

6 6 Energy Harvesting (Scavenging) Principle: Energy is extracted from the surroundings Surroundings Energy CONVERSION Electrical domain CONDITIONING LOAD Environment Human body Radiant Kinetic Thermal The load can be: - Electronic circuits and devices - Sensors with wireless communication Autonomous Sensors - Radiant Energy Harvesting Principle: Energy is extracted from the surroundings Energy CONVERSION Electrical domain CONDITIONING LOAD Radiant Energy

7 7 Radiant Energy: Solar Solar areal power density (outdoor at noon): 100 mw/cm Efficiency (average): 10-15% Electrical areal power density: mw/cm Indoor is orders of magnitude less Radiant Energy: Radio Frequency Capture exisiting or purposely transmitted electromagnetic RF energy and convert it into electrical energy Use of a rectifying antenna: rectenna Assuming no reflections or interferences: transmitted power P 0 = 1 W frequency f =.4 GHz (ISM) distance R = 5 m P0 received power P r P r 4 R P r = 50 W Background power levels are typically very low and difficult to exploit at present

8 8 Mechanical Energy Harvesting Principle: Energy is extracted from the surroundings Energy CONVERSION Electrical domain CONDITIONING LOAD Mechanical Energy MechanoElectrical Conversion Magnetic induction conversion Electrostatic conversion Piezoelectric conversion

9 9 MechanoElectrical Conversion Magnetic induction conversion: Magnetic induction conversion Electrostatic conversion Piezoelectric conversion NightStar flashlamp MechanoElectrical Conversion Magnetic induction conversion: Magnetic induction conversion Electrostatic conversion Piezoelectric conversion

10 MechanoElectrical Conversion Magnetic induction conversion: Magnetic induction conversion Electrostatic conversion Piezoelectric conversion MechanoElectrical Conversion Electrostatic conversion: Magnetic induction conversion Electrostatic conversion UCB, Berkeley, USA Piezoelectric conversion UCB, Berkeley, USA V.Ferrari MIT, Boston, USARF&Wireless Forum - Milano,

11 MechanoElectrical Conversion Piezoelectric conversion: Magnetic induction conversion Electrostatic conversion NEC -Tokin, Japan Piezoelectric conversion V.Ferrari MIT, RF&Wireless Boston, USAForum - Milano, Thermal Harvesting Principle: Energy is extracted from the surroundings thermal gradients Energy CONVERSION Electrical domain CONDITIONING LOAD Thermal Energy 11

12 1 Thermal Energy: Thermoelectric Conversion Seebeck effect: V G ab ab = Seebeck coefficient heat source Th T H T C a T C T H b _ V + b G P-type h + e - N-type heat sink Tc + _ V G The Figure of Merit ZT TH TC Carnot efficiency: TH 1 Maximum thermoelectric efficiency: ZTT 1 max 1 ZT T C H The parameter ZT T = Seebeck coefficient ZT should be maximized An effective parameter Z e T < ZT accounts for losses T = temperature = electrical conductivity = thermal conductivity

13 13 Thermoelectric Conversion Examples Seiko Thermic watch: Air/Soil energy harvester: Human++ Project: Reed College, Portland & CALTEC, USA Power Bolt & Power Probe: IMEC, Leuven, Belgium Mechanical Energy Harvesting Direct deformation (strain) E.g. piezoelectric fiber composites Impact & transient loads E.g. piezoelectric thin plates Vibrations Seismic-mass inertial system THUNDER, Face International Corp, USA. (approximated for piezoelectric converters) C.B. Williams, R.B. Yates,, Sens. Actuat. A 5, 8-11 (1996). Unfavorable scaling with reducing dimensions

14 Microscale Energy Converters Next generation Tire-Pressure Monitor Systems (TPMS) will dismiss batteries and rely on energy harvesting Macroscale Energy Converters: commercial examples 14

15 V L [V] V L [V] acceleration [g] P L [ W] P L [ W] 15 Macroscale Energy Converter 1.0 L W = 15mm L = 40mm T = 500μm u F W T C P =151pF R P =363M PZT: Piezokeramika 856 d 33 = 590pC/N d 31 = -60pC/N r = 4000 i V BEAM PIEZOELECTRIC LAYER A = 13.6V) C L [pf] V.Ferrari M.Ferrari et al., IEEE Trans. Instrum. Meas. 55, (006). RF&Wireless Forum - Milano, Resistive load R L Computed Experimental R L [M ] f [Hz] Capacitive load C L Computed Experimental Computed Experimental R L (M ) Computed Experimental C L [pf] Autonomous Sensor with RF Link vibrations Piezoelectric Converter V P C b Rectifier and storage capacitor V C Sensing and switching sensor DC Voltage regulator MAX666 Oscillator V R+ V R- RF Transmitter 315 MHz RF Receiver! No battery, no internal power sources! Intermittent operation The sensor (R or C) is inserted into an oscillator The oscillator frequency gives a OOK modulation of the RF carrier The measurement information is carried in the time domain

16 Autonomous Temperature Sensor VP VR+ VC DC Cb Piezoelectric Converter vibrations Rectifier and storage capacitor Sensing and switching sensor Voltage regulator VRRF Transmitter RF Receiver Oscillator Thermistor response curve NTC Epcos K164/10k f OSC Sensitivity: 1.44 ( R1 RS )CS ST 1.3 khz C 10 Hz Standard deviation (30 repetitions): Resolution: 3 ST RT V.Ferrari 30 Hz 1.3 khz C 0.03 C RF&Wireless Forum - Milano, Autonomous Multi-Sensor Module SENSOR SENSOR 1 Impedance Controlled Oscillator RF Transmitter Impedance Controlled Oscillator 1 SPDT switch Cb Piezoelectric converter Monostable DC Voltage regulator VC Mechanical Vibrations Rectifier and storage capacitor Sensing and switching A digital ID-code can also be transmitted for module tagging and tracking V.Ferrari RF Receiver 0 A.U. The piezo harvester powers a module comprising sensors Energy is sequentially switched between the sensors Signals are transmitted in time multiplexing Vc,VRX [V] M. Ferrari et al., Smart Mater. Struct., 18, (009) Time [ms] RF&Wireless Forum - Milano,

17 Vo/Vi [db] 17 MultiFrequency Converter Array Multiple converters combined to obtain a wider equivalent bandwidth: f [Hz] 3 MFCA on the vibration exciter (shaker). Silicon MEMS with PZT films: Design: University of Brescia Fabrication: CNM, Barcelona, Spain In collaboration with: 500 m M. Ferrari et al., Sens. Actuat. A 14, (008). ThermoElectric Generators (TEG) Commercial Peltier modules tested as ThermoElectric Generators (TEGs) R L V G R in TEG I L h l H L Label Model N Couples l [mm] h [mm] L [mm] H [mm] N/Area [couples/cm ] R in [ ] K in [W/K] TEG 1 TMG TEG PE TEG 3 TMG

18 V G [V] P L [mw] 18 ThermoElectric Generators (TEG) Commercial Peltier modules tested as ThermoElectric Generators (TEGs) TEG TEG 1 TEG ideal model model with thermal resistance T = 10K T [K] R L [ ] Label Model N Couples l [mm] h [mm] L [mm] H [mm] N/Area [couples/cm ] R in [ ] K in [W/K] TEG 1 TMG TEG PE TEG 3 TMG TEG-powered Autonomous Sensor T H Q H Charge pump Transmitter Receiver TEG V O DC/DC V OUT Conditioning circuit T C Q C V OSC TEG #3 Sensor and conditioning circuit R sens DC/DC converter TPS60303: V OUT = 3 V Sensor + oscillator RF low-power transmitter MAX 147: OOK modulation@433.9 MHz TEG Sensor For T = 30 K the system turns on steadily S.Dalola et al., IEEE Trans. on Instrum. Meas., 58, (009).

19 TEG-powered Autonomous Sensor QH TH Transmitter Charge pump TEG DC/DC VO Conditioning circuit VOUT QC TC Receiver VOSC Rsens tenable s ttx = 330 ms Sensor and conditioning circuit. ttx tenable TX U. A.. V [V] Sensor For T = 30 K the system turns on steadily PLmax = 31.8 mw 3.4 TEG Enable V.Ferrari Time [s] 10 RF&Wireless Forum - Milano, Embedded Autonomous RF Sensors METADISTRETTI 006 Bialetti Industrie (project Leader) DEA Università di Brescia INDACO PoliMi Tecnotransfer (Bs) Cartotecnica Marella (Bg) Experimental study: V.Ferrari RF&Wireless Forum - Milano,

20 0 Embedded Autonomous RF Sensors Property of Bialetti Industrie SpA Patent pending Embedded Autonomous RF Sensors Property of Bialetti Industrie SpA Patent pending

21 1 Final Comments Energy harvesting for sensors is a fast-growing area evolving from gadgets to enabling technology in such fields as: Industrial control and automation Transport, automotive, avionics Power plants & distribution Structural monitoring Medical and healthcare Security and military University of Brescia is active in the field with: Applied research programs Projects in cooperation with industrial Partners Università di Brescia: Acknowledgments Marco Baù Simone Dalola Marco Demori Marco Ferrari Michele Guizzetti Daniele Marioli Emanuele Tonoli Stefano Zaiba