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Design, Modelling, Fabrication & Testing of a Miniature Piezoelectric-based EMF Energy Harvester

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Tim Pollock

on 9 July 2014

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Transcript of Design, Modelling, Fabrication & Testing of a Miniature Piezoelectric-based EMF Energy Harvester

Design, Modelling, Fabrication & Testing of a Miniature Piezoelectric-based EMF Energy Harvester
Introduction and Motivation
Objective & Scope of Research
Harvesting Concepts & Relevant Research Work
Design and Modelling
Experimental Results and Model Comparison
Conclusion and Future Work
Introduction and Motivation
"The conversion of ambient energy into electrical energy" [1].
What is Energy Harvesting?
Introduction and Motivation
Demand for Wireless Sensors
Monitoring applications
Data acquisition
Environmental Responsibility
Decreasing fossil fuels
Increased hazardous waste
Cost Savings
No expensive cabling needed
Battery associated maintenance
Reduced reliance on fossil fuels
Battery waste disposal costs
Why Energy Harvesting?
[1] Danial J. Inman Alper Erturk. Piezoelectric Energy Harvesting. Wiley, Chichester,
West Sussex, U.K. Hoboken, N.J, 2011.

[2] R. O'Donnell. Energy harvesting from human and machine motion for wireless electronic devices. Proceedings of the IEEE, 96(9):1455{1456, 2008.

[3] Danial J. Inman Alper Erturk. Piezoelectric Energy Harvesting. Wiley, Chichester,
West Sussex, U.K. Hoboken, N.J, 2011.

[4] Shadrach Joseph Roundy. Energy Scavenging for Wireless Sensor Nodes with a Focus on Vibration to Electricity Conversion. PhD thesis, THE University of California,
Berkeley, 2003.
Green Energy
Magnetic Fields
Radio waves
Thermal Gradients
Energy Harvesting
Introduction and Motivation
Powering Wireless Electronics!
What can we use Energy Harvesting for?
Remote sensor applications
Power grid
Objective & Scope of Research
Design a miniature energy harvesting unit to power current sensors mounted on single wire power transmission lines.
Primary Sources of Energy
Operating frequency of 60 Hz
Miniature in size (Volume < 3 cm^3 & length < 30 mm)
Prototype to be tested on a conducting wire carrying between 1-15A for proof of concept.
Optimization efforts
Maximize magnetic force
Minimize material cost for a given application
Development of an accurate analytical electromechanical model of the system
Design Requirements
Harvesting Concepts & Previous Relevant Work
Kinematic Harvesting Techniques
Electrostatic Harvesting Principle
When two oppositely charged plates (separated by air, vacuum or insulator) are mechanically forced against one another, a charge or voltage is produced which can be harvested.
Uses Faraday's law of induction for the energy transduction mechanism. An inductor coil placed in the presence of a changing magnetic field causes current flow in the coil.
Piezoelectric Harvesting Principle
Stress applied to the material induces a mechanical strain as well as an electric displacement. A voltage applied to the material an electric displacement and mechanical strain is induced.
Electromagnetic Harvesting Principle
Electromagnetic Flux Radiation
Ease of integration into MEMS designs
Low energy density
Approx. 2-10V output voltages for miniature applications
External charge required
Bulky configurations
Output depends highly on the number of turns in the coil.
Low output voltages
Good energy density
Highest energy Density
Approx. 2-10V outputs for miniature applications
High output impedance
No external charge needed
Harvesting Concepts & Previous Relevant Work
Electromagnetic Field Energy
Harvesting Concepts & Previous Relevant Work
Harvesting Concepts & Previous Relevant Work
Harvesting Concepts & Previous Relevant Work
Design and Modelling
General Concept Design
Energy Density Summary
Design and Modelling
Electromagnetic Force Modelling
Design and Modelling
Final Harvester Design
Design and Modelling...
Piezoelectric Material Selection
Electromechanical Analytical Model
Design and Modelling
Design Considerations
Permanent Magnet
Maximizing Force
Magnet remenance
Magnet orientation
Magnet Size & Geometry
Flat mounting location
Minimize mount location
High Material Density
Cantilever Beam
Piezoelectric material
Substrate material
Tuning method
Adjustable piezoelectric length
Boundary Conditions
Design and Modelling
3 Step Experimental & Modelling Approach
1) Base Excitation using Shaker
Harvester dynamics characterization
Electrodynamic Shaker Control
Minor tuning more easily done
Optimal power resistance determination
Well defined analytic models exist
2) Tip Excitation (wire) using Controlled Current
Controlled current signal through wire
Current reference feedback
3) Tip Excitation (wire) using Wall Current
Multiple average tests
"Energy Coupler" Bhuiyan et al.
280 turn coil around 8 flexibly mu-metal core layers (50 x 45 x 4mm)
Voltage output highly dependent on # of coil turns
Requires voltage multiplier circuitry
Flux leakage due to core gap
Tens of mW power output at 13.5 Amps current through conductor
"Power Donut"
Relatively heavy (9.2 Kg)
Large in size (320 x 140mm)
Requires maintenance (5 year)
No power output info available
Piezoelectric Harvester, Leland et al.
Continuous piezoelectric bimorph cantilever beam
Axially poled disc magnets used as tip mass
Miniature in size (31.8mm x 3.2mm x 0.38mm)
Power output of 345 microW for 60 Hz 13A current through the conducting wire
No magnet optimization or piezoelectric optimization considered
Piezoelectric Sensor, Lao et al.
Discontinuous piezoelectric bimorph cantilever beam
Axially poled disc magnets used as tip mass
Magnetic force optimization
Miniature in size (26mm x 14.45mm x 1.68mm)
Sensitivity of 3mV/A @ 5mm distance to the conductor
Linear Elastic
Linear Dielectric
Constitutive Equation for Piezoelectric Material
Reduce Equation for Cantilever Beam
Substrate Material Selection
Cantilever Natural Frequency
Cantilever Tip Deflection
Proportionality Constant
Design and Modelling...
Three section cantilever beam
Conventional Euler-Bernoulli assumptions
Coupled PDE for section 2
Continuity equations used in addition to fixed-free boundary conditions
Experimental Results and Model Comparison
Resonance Tuning, Optimal Resistance & Damping
Design and Modelling...
Overall Design (EH10)
Complete harvester including clamp 60 x 50 x 25mm.
Series electrical connection using lead solder.
60 Hz Frequency design with 10 mm (arbitrary) PZT-5A material.
Electrodynamic shaker for base excitation.
Laser vibrometer for displacement measurement.
Accelerometer for reference feedback.
BNC connector for voltage measurement.
LMS Data acquisition system and software.
Sine sweep 10-120Hz at an acceleration of 0.2 g's.
Experimental Results and Model Comparison...
Test 1: Base Excitation
Maximum Power Resistance
Resonance Tuning
Damping Characterization
Experimental Results and Model Comparison...
Electrodynamic shaker used as load (custom cable).
Harvesters mounted on top a 10 AWG copper conductor.
Magnet offset distance 6mm.
Current Clamp (10mv/A) for reference feedback.
Sine sweep 20-120Hz at 1.5 amps constant current.
0.1 Hz/s sweep rate at 0.1 Hz resolution.
Test 2: Tip Excitation (EMF Amp Current)
Experimental Results and Model Comparison...
Test 2: Tip Excitation (EMF Amp Current)
Experimental Set-up
Experimental Set-up
Experimental Results and Model Comparison...
Variable heater used as load (3 settings).
Tested current values of approx. 0.28A, 8.4A and 16.5A.
25 averages for each measurement.
0.125 Hz frequency resolution.
Test 3: Tip Excitation (EMF Wall Current)
Experimental Results and Model Comparison...
Experimental Set-up
Test 3: Tip Excitation (EMF Wall Current)
1) Half-power Bandwidth method (HPB)
2) Closed-form Expression (CFE), Erturk et al. [3]
Non-dimensional expression
High degree of accuracy for base excitation modelling
Damping Ratios
Peak Values
Damping Ratios
Peak Values
Conclusions and Future Work
Effective energy harvesting technology.
Design has been magnetically optimized
Model and experimental show good agreement
Cost optimized
Future Work & Improvements
High current testing.
Fatigue testing.
Temperature sensitivity.
Scalability (MEMS)
Improve manufacturing.
Improve tuning.
Roundy et al. [4]
510 High Strength Bronze
Prezi Sources
Masters of Applied Science Thesis Seminar
Prepared by: Tim Pollock
Supervisor: Armaghan Salehian
Date: May 9th, 2014

Advantages & Disadvantages
9.2 kg !!!
Objective & Scope of Research
Maximize Force: Orientation, Geometry, Materials Constants
Coupled Mechanical Equation of Motion
Coupled Equations of Motion
Design and Modelling
Design and Modelling
Transverse Displacement
Coupled Beam Equation
Three section cantilever beam.
Euler-Bernoulli assumptions.
Internal Bending Moment
Backwards Electromechanical Coupling
Mode Shapes, Boundary and Continuity Conditions
Modal Expansion Theorem
Fixed-free boundary conditions.
Two sets of continuity conditions.
Piecewise mode shapes.
Piecewise Mode shapes
Series electrical connection.
Gauss Law
Coupled Electrical Circuit Equation
Boundary Conditions
Modal Coupling
Circuit Representation
Kirchhoff's Law
Circuit Representation
Coupled Mechanical Equation of Motion
Coupled Electrical Circuit Equation
Steady State & FRF Responses
Voltage Response
Voltage FRF
Power Response
Power FRF
Displacement Response
Displacement FRF
Forcing Functions
PDE - Base Excitation (Shaker)
Base Excitation (Shaker)
After Modal Expansion & Orthogonality Conditions
Harmonic Input Function
PDE - Base Excitation (Shaker)
Tip Excitation (EMF Conducting Wire)
After Modal Expansion & Orthogonality Conditions
Piezoelectric Relationship
Matlab Modelling Process
Design and Modelling...
1) Construct the 12 x 12 characteristic equation

2) Set all material constants, geometric values and electrical resistance to the appropriate quantities.

3) Set the determinant of the characteristic equation to zero and numerically evaluate for the perfect length to achieve a 60 Hz frequency.

4) Conduct modal analysis

5) Calculate electromechanical coupling and input force

6) Plot experimental results and calculate damping ratios

7) Calculate and plot frequency response functions
The hydro line itself
Energy Scale
Constant Frequency of 60 Hz
Damping Ratio 0.00592
Short circuit conditions
15 amp input current
Full transcript