BENCHMARKING OF PIEZOCERAMIC MATERIALS FOR GENERATOR APPLICATION

Transcription

1 BENCHMARKING OF PIEZOCERAMIC MATERIALS FOR GENERATOR APPLICATION Thomas Rödig

2 OUTLINE Introduction Benchmarking of piezoelectric materials Energy output Degradation Proof of concept Conclusion and outlook

3 Introduction - Historical Overview 1880 Discovery of the piezoelectric effect 1950 General use of piezoelectric generator (Mason) 1959 Piezoelectric spark igniters claimed 1972 U.S. patent about a gas ignition device J. Schroder, H.G. Ganser and H. Öpen: Piezoelectric Ignition Device ; U.S. Patent G. W. Ledenbach, A Piezo Powered Ic Transmitter, IEEE Trans. Consumer Electron., CE-26, , 1980, doi: /TCE today First possible application using piezoelectric generators in combination with low-power electronics Enocean starts commercializing wireless light switches (enocean) Diversification of research objectives and markets, analysis of marketability

4 Introduction Design of a piezoelectric generator Mechanical Sources Mechanical Transformer Piezoelectric Transducer Electrical Transformer Load Force p F = A p F MFC Pressure Rectifier Acceleration Moment F = m a Stack and Multilayer Generators Storage Displacement F = M l [source: Transformer

5 Introduction - Material Requirements vs. Applications Typical application Material requirements Availability Ultrasound NDT, medical imaging High electromechanical coupling (pulse-echomethod) High power Low losses yes yes Sensor Acceleration Linearity, temperature stability yes Actuator Fine positioning, valves and pumps High strain and force yes Generator Igniters Low power electronic High voltage, high breaking strength, high breakdown voltage, low degradation yes High power generation, low voltage, low degradation?

6 Piezoelectric generator effect A 2+ Ion O 2- Ion U=0V B 4+ Ion middle layer bound charge free charge U=0V Voltage: (open circuit) U d ε T F g T F mechanical load lateral extension Charge: (short circuit) Q d F U>0V contraction U>0V Energy: d E ε 2 T F 2

7 Ferroelectric generator effect A 2+ Ion O 2- Ion U=0V B 4+ Ion middle layer bound charge free charge U=0V Domain switching Reversible higher charge release U>0V mechanical load lateral extension contraction U>0V Irreversible material degradation

8 Combination of piezoelectric and ferroelectric effect lattice distortion and properties of PZT-SKN g 33 ε 33T / ε 0 mv /N 2200 l/l, k p d 33, pc/n PbZrO

9 Benchmarking Energy Output > 200 materials available 47 materials under investigation at IKTS Interesting values: Charge constant: d 33 = pc/n Voltage constant: g 33 = d 33 / ε 33 = mvm/n Energy density constant: w T 33 = d 33 g 33 = 100 mj/cm³ increasing voltage output increasing charge output 10 1 MPa

10 Benchmarking - Depolarisation Soft material Materials composition Loads Prestress Dynamic piezoelectric charge constant [pc/n] soft/hard material hard material

11 Benchmarking - Depolarisation Depolarization behavior assumed depends on energy density level Property Unit PZT 4 PZT 5A PZT 5H PZT 8 Piezoelectric stress energy density constant (10 10 ) J/m³ Maximum tolerable pressure In poling direction (static) In poling direction (dynamic) MPa Perpendicular to poling direction (static) low depolarization high depolarization

12 OUTLINE Introduction Benchmarking of piezoelectric materials Energy output Depolarisation Proof of concept Conclusion and outlook

13 Proof of Concept Leading-Edge-Project The project CoolSensorNet is part of the Leading-Edge Cluster Cool Silicon, which is sponsored by the Federal Ministry of Education and Research (BMBF) within the scope of its Leading-Edge Cluster Competition Aim: next generator aircrafts made of carbon fiber reinforced materials Example: Boeing Dreamliner Airbus A350 Challenge: Structural health monitoring Lifetime 30 years

14 Proof of Concept Starting Situation and Requirements Origin: stall at the fuselage Low vibration amplitude 500 Hz 1 µm) High frequency Electrical requirement: Voltage = 3.3Vdc Acceleration 1g Source: aircarft industry Power > 100 µw 500 Hz 1 khz 5 khz

15 Proof of Concept Generator Design and Material Selection Material selection: High voltage constant Soft/hard, medium depolarization High energy output

16 Proof of Concept Results 1g, f R, load resistor: Generator P max [µw] U [V] I [µa] Single element Four element four element generator single element

17 Proof of Concept Electric transformer LTC /medium/LTC3588.jpg

18 Conclusion and Outlook Commercial piezoceramic materials for generator applications available Wide range of Charge constant Voltage constant Degradation resistance Proof of concept of SHM power generator successfully finished Next step is designing a new electronic modul to power low power electronics