**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

Agenda

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

Sustainability

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.

Solar

Wind

Hydro

Geothermal

Green Energy

Vibration

Magnetic Fields

Radio waves

Thermal Gradients

Energy Harvesting

Introduction and Motivation

Powering Wireless Electronics!

What can we use Energy Harvesting for?

Remote sensor applications

Bridges

Pipelines

Automobiles

Power grid

Objective & Scope of Research

Solar

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

Electromagnetic

Piezoelectric

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

Wind

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

Adjustability

Versatility

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

Constants

Thickness

Width

Length

Stiffness

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

Conclusions

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]

PZT-5A

510 High Strength Bronze

Questions

Prezi Sources

**Masters of Applied Science Thesis Seminar**

**Prepared by: Tim Pollock**

Supervisor: Armaghan Salehian

Date: May 9th, 2014

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

Continuity

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

Strain

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