Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 1
DESIGN AND ANALYSIS OF OCEAN WAVE INDUCED PERMANENT MAGNET
ENERGY GENERATOR
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Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 2
ABSTRACT
Currently, many technologies are geared toward renewable energy harnessing. However,
the mode of harnessing energy or storage is constrained by many limitations. This technological
gap have halted the extent of innovation of renewable energy harnessing technologies otherwise
many advance energy generation technologies would have resulted good ratio between
renewable and non-renewable energy sources. Utilizing a moving permanent magnet inside a coil
stator to generate varying magnetic field has been proposed some time ago and it has been used
at many places for energy generation. Current work make use of permanent magnet linear
generator. Generation of voltage from the oceanic wave depends on the behaviour of the oceanic
waves and interaction with generator. This thesis has proposed a design of permanent magnet
linear generator which is used for the conversion of wave energy to voltage. A mathematical
model has been used to calculate the electrical energy production, efficiency etc. A numerical
model has also been done to analyse the magnetic field generation and corresponding voltage
generation in ANSYS/ANSOFT Maxwell software which gives magnetic flux density, magnetic
field intensity etc. as an output. An analysis has been performed in Solidworks for loads that
come due to magnetic fields (repulsion) as well as self-weight. Different time of a year have
different sea wave condition hence permanent magnet linear generator has to be analysed for
different conditions.

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 3
ACKNOWLEDGEMENTS
I would like to thank my tutor for helping me throughout the project work at every possible
instant and difficulty. He always kept open door policy for every possible query during the entire
work.
Also, I would like to extend my gratitude to university staff (librarian) to allow me to use
knowledge base and library of university for research purpose.
My parents always kept me motivating to work harder and made all other resources available to
me to get this work completed.
Finally, I would like to thank almighty whose kindness has helped me steer through his project.
Author

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 4
TABLE OF CONTENTS
ACKNOWLEDGEMENTS............................................................................................... 3
1.0 INTRODUCTION............................................................................................... 10
1.1 Aim.................................................................................................................. 10
1.2 Objectives....................................................................................................... 10
1.3 Background of the study.................................................................................11
1.4 Significance of the study.................................................................................12
2. LITERATURE REVIEW.......................................................................................... 13
2.1 Definition and examples of wave energy........................................................15
2.2 Permanent Magnet Linear Generator (PMLG) – Design, components and
parameters............................................................................................................ 15
2.3 Overall power equation for sea wave..............................................................16
2.4 Disadvantages of harnessing ocean energy....................................................17
2.5 Scope of application of PMLG..........................................................................18
3. METHODOLOGY.................................................................................................. 27
3.1 Principle of the PMLG...................................................................................... 27
3.2 Development of PMLG..................................................................................... 27
3.3 Selection of vector diagram and circuit...........................................................28
4. Numerical Model using ANSYS Maxwell for Permanent Magnet Linear Generator
(PMLG)...................................................................................................................... 30
4.1 Construction Details........................................................................................ 30
4.2 Materials details.............................................................................................. 33
4.3 Boundary conditions, meshing and transient analysis set-up.........................36
5. PRELIMINARY RESULTS......................................................................................... 38
6. Static analysis of permanent magnet generator using Solidworks.......................44
7. Pros and Cons of PMLG......................................................................................... 51
7. Analytical Calculations of permanent linear magnet generator............................51
8. Summary & Conclusion........................................................................................ 55
9. Future scope......................................................................................................... 56
REFERENCES............................................................................................................ 58

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 5
List of figures
Figure 1: Typical schematic plot of PMLG consisting of Stator, translator with
permanent magnets................................................................................................. 17
Figure 3: Directional vector plot showing phase angle difference in induced voltage
................................................................................................................................. 18
Figure 4: Series connected coils on stator of PMLG as connected with loads...........19
Figure 5: 2D Axi-symmetric construction of PMLG....................................................19
Figure 6: Position of Translator at Different Time.....................................................21
Figure 7: Schematic of Translator and Stator for pole pitch assessment..................22
Figure 8: Practical implementation of PMLG along with buoy...................................23
Figure 9: Translator position in PMLG.......................................................................26
Figure 10: Modelling dimensions of Translator in ANSYS Maxwell............................29
Figure 11: Half-symmetric model of linear permanent magnet generator in ANSYS
Maxwell.................................................................................................................... 29
Figure 12: Modelling parameters for stator in ANSYS Maxwell.................................30
Figure 13: Modelled stator teeth to insert stranded coils inside ANSYS Maxwell......30
Figure 14: Integrated model in ANSYS Maxwell tree along with assigned material. .31
Figure 15: Properties of Copper used in Magnetic coils used in current analysis.....32
Figure 16: Properties of NdFe35 used in permanent magnets used in current
analysis.................................................................................................................... 32
Figure 17: Properties of steel 1010 used in stator used in current analysis.............33
Figure 18: Properties of Copper used in Magnetic coils used in current analysis.....33
Figure 19: Motion setup of translator as used in current analysis............................34
Figure 20: Overall model tree of linear generator in ANSYS Maxwell.......................35
Figure 21: Transient setup settings used in ANSYS analysis....................................35
Figure 22: Magnetic flux density (B) as a result of ANSYS analysis for 1000 RPM....36
Figure 23: Magnetic flux linkage between 2 modelled windings..............................36
Figure 24: Induced voltage (V) in 2 different coils modelled as 2 different phases in
ANSYS Maxwell analysis........................................................................................... 37
Figure 25: Magnetic flux density (B) from ANSYS analysis - translator speed of 2000
RPM.......................................................................................................................... 37
Figure 25: Magnetic flux density (B) from ANSYS analysis - translator speed of 3000
RPM.......................................................................................................................... 38
Figure 26: Magnetic flux density (B) from ANSYS analysis - translator speed of 4000
RPM.......................................................................................................................... 38
Figure 27: Magnetic flux linkage between 2 windings at different phases for
translator speed of 2000 RPM from ANSYS analysis.................................................39
Figure 28: Induced voltage on 2 windings at different phases for translator speed of
2000 RPM from ANSYS analysis................................................................................ 39

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 6
Figure 29: Magnetic flux linkage between 2 windings at different phases for
translator speed of 3000 RPM from ANSYS analysis.................................................40
Figure 30: Induced voltage on 2 windings at different phases for translator speed of
3000 RPM from ANSYS analysis................................................................................ 40
Figure 31: Magnetic flux linkage between 2 windings at different phases for
translator speed of 4000 RPM from ANSYS analysis.................................................41
Figure 32: Induced voltage on 2 windings at different phases for translator speed of
4000 RPM from ANSYS analysis................................................................................ 41
Figure 33: Modelled quarter symmetric geometry of PMLG in Solidworks................42
Figure 34: Initial mesh on PMLG as used in iteration 1.............................................43
Figure 35: Refined mesh on PMLG as used in iteration 2.........................................43
Figure 36: Refined converged mesh on PMLG as used for final analysis..................44
Figure 37: Displacement constraints on top face of PMLG.......................................44
Figure 38: Displacement constraints on bottom face of PMLG.................................45
Figure 39: Symmetric boundary condition applied on left face of PMLG..................45
Figure 40: Symmetric boundary condition applied on right face of PMLG................46
Figure 41: Forces applied on stator in PMLG............................................................46
Figure 42: Forces applied on translator in PMLG......................................................47
Figure 43: Displacement plot for 2 different RPM configurations (different Lorentz
forces) in PMLG......................................................................................................... 47
Figure 44: Stress plot for 2 different RPM configurations (different Lorentz forces) in
PMLG........................................................................................................................ 48
Figure 45: Strain plot for 2 different RPM configurations (different Lorentz forces) in
PMLG........................................................................................................................ 48

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 7
List of tables
Table 1: Obtained PMLG Values of fig 15...................................................................................31
Table 2: Obtained PMLG Values of fig 16...................................................................................32
Table 3: PLMG dimensions...........................................................................................................37
Table 4: PLMG parameters...........................................................................................................38

Design and Analysis of Ocean Wave Induced Permanent Magnet Energy Generator 8
1.0 INTRODUCTION
Sea wave energy or ocean wave energy is a source of renewable energy that can be harnessed
to generate electricity at minimal cost equipment and across many locations where access to
coasts are available. Sea waves keeps oscillating with varying magnitude and frequency
throughout the seasons but for a particular season, it might remain in a certain range. This
periodicity of the sea waves can be used as a periodical low-frequency mechanical energy
sources that has the potential to convert this wave motion into electricity through generators. The
plan of current study is to analyse one such ocean wave energy generator which can exploit this
mechanical sea wave energy to produce electricity. To explore options to exploit this mechanical
sea wave energy, a linear permanent magnet generator has been studied in current work. This
kind of permanent magnet linear generator has been used at many other locations such as wind
energy also where the way of rotation of turbines to magnet movement has to be changed. The
working principal of magnet generator using voltage induction to generate electricity and hence
its application. (Akpınar & Kömürcü., 2013).
1.1 Aim
The report aims at studying a proposed design of permanent magnet sea wave electricity
generator and effect of varying sea wave parameters such as wave height, wave frequency on the
extent of energy generated. This is done using analytical as well as numerical calculations.
1.2 Objectives
 To study an existing design of permanent magnet linear generator and its parameters to
model generate electricity with given sea wave parameters
 To use analytical or mathematical models to study generated electricity