Contents or motors. One of the efficient solution

 
 
 
 
 
 

 

Contents
List of figures. 3
1.0      Introduction. 4
2.0      Aims and objectives. 7
3.0      Literature review.. 8
4.0      Project management
(Gant chart) 11
5.0      Progress of the work. 13
5.1 Design of
permanent magnet machine. 13
5.3 Finite element
analysis. 14
6.0      Summary and
conclusion. 16
References. 17
Appendices. 18
Appendix 1- Figures
and drawings. 18
 

 

 

 

 

 

 

 

 

 

List of figures

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

Figure 1: Air
gap windings in axial flux permanent magnet 18

Figure 2:
Permanent magnet rotor with multipoles. 18

Figure 3:
Modular assembly of multipole permanent magnet rotor. 19

Figure 4:
Initial CAD model of permanent magnet machine. 19

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.0   Introduction

The global consumption of energy in the form of electricity in
the year 2016 as reported by the united states government agency was
approximately 22000TWh (Yearbook.enerdata.net, 2018). The growth of electricity
consumption is rapid, and it is predicted to reach 30116 TWh in the year 2030. These
days one of the most important goals for international energy policy is to
prevent climatic change, i.e. reduce global worming effect. Therefore, it is
predicted that carbon dioxide emission will be little as compared to present
scenario. To achieve maximum electricity production to cater ever growing
requirement of electricity with reduced carbon footprint it is necessary for
all the countries to adopt efficient renewable energy sources such as solar and
wind, without the help of renewable natural energy sources to produce
electricity it is impossible to reduce ambitious carbon foot print goal
globally (Aleksashkin
and Mikkola, 2008).  

Generators and motors, which are
essentially electromechanical energy conversion devices play a crucial role in
energy production and consumption. To reduce carbon emission that adhere to
international policies but also meet the demands of the ever-growing energy
market its necessary to focus on renewable energy and to enhance the
efficiencies of electromechanical energy conversion devices such as generators
or motors. One of the efficient solution can be permanent magnet technology for
electromechanical power consumption. It is possible to create competitive
distributed energy technology with new conversion apparatus due to
sophistication of available energy conversion technologies with permanent
magnets. Direct driven windmill generators is one example of such development
as it can be enhanced by utilizing the benefits of permanent magnet technology.

Industrial use of the permanent
magnet started since the invention of very first permanent magnet at the
beginning of the 20th century. For electric machines such as
rotating as well as linear machines permanent magnet motors are used which is
the well-known application. Permanent magnet motors are in use for decades in
various applications due to its low initial cost and simple structural
requirements. The applications of permanent magnet machines have been exploited
recently for more challenging tasks due to improvement of permanent magnet
characteristics and low cost. Therefore, it is found that most modern
applications of permanent magnets are efficient as well cost competitive (Aleksashkin
and Mikkola, 2008).

This project work is an effort to
design the permanent magnet machine for the application of wind turbine. The
need and benefits of using permanent magnet machines are briefly described in
earlier paragraphs. One of the benefits mentioned such as reducing global warming
or carbon emission or basically making earth greener and getting it rid of
pollutants is one of the main motivations for me to select this topic for my
project. The primary motivation for the project work is the needed initiative
to reduce the carbon foot print in the field of electricity production, which
can be achieved by utilising renewable natural resources considering present scenario.
The permanent magnet machines are the possible solution due to various benefits
offered by them with competitive cost.

 

 

 

 

2.0   Aims and objectives

Aim of this project work is to
design a permanent magnet motor for application in wind turbine. To achieve
this aim successfully following objectives have been laid down,

–         
To
carry extensive research, online as well as offline on permanent magnet
motors/generators and wind turbine

–         
To
select a wind turbine to understand the capacity that will help the design

–         
To
study and design different components of the permanent magnet of the motor
based on requirement of wind turbine, this objective need extensive study as it
will have required to design or select the power density/torque, efficiency, operating
speed etc

–         
Finite
element analysis of the design to find the suitability of the design for wind
turbine under various conditions

It is necessary to note that, a
wind turbine is a huge device, therefore actual assembling and testing of the
permanent magnetic machine will be costly at academic level, therefore, the
efforts will be taken to scale down the wind turbine to a level which
assembling of prototype and testing of the permanent magnetic machine will be
cheap in terms of cost.

 

3.0   Literature review

All electromagnetics energy
conversion devices which incorporates permanent magnet technology are described
by the term ‘permanent magnet machine’. A single or multiple permanent magnet
are used for magnetic excitation. Variety of configurations could be found in
the energy converter that employs permanent magnet technology, several examples
are, generator, motor, stepper motor, alternator, actuator, linear motor,
control motor, transducer, brush less DC motor, tachometer and many more. The
stator of the motor is like the stator of the multiphase AC motor. The new
component incorporated in the permanent magnet motor is rotor, the rotor is
complete contrast to that of conventional rotors. In this application, rotor
relies of magnetic excitation unlike excitation by electric current in the
winding of multiphase AC motors. To achieve the higher efficiency for the
desired load characteristics, high efficiency, high power factor as well as
performance, it is necessary to optimise the configuration of the rotor,
mechanical design and electromagnetic rotor and the design of the
electromagnetic stator (Rizk et al, 2000). The direct drive wind turbine
application requires a machine with high power density, high power torque, high
efficiency with low design operating speed. The primary reason to use direct
drive permanent magnet machine is that the machine has an ability to reduce the
cost of converting wind power to mechanical power simply by eliminating the
necessity of step up gear box. The speed increasing gear box is usually incorporated
in wind mill to amplify the small rpm of the wind rotor to higher rpm to
produce electricity. The cost associated for the operation as well as
maintenance of direct drive permanent magnet machine is very low as compared to
gear coupled machines. The role of low speed, high power direct drive electric
machines are extensively limited to special applications such as large
hydroelectric generators therefore they are not commonly used in the industry.
Therefore, low speed and high torque motors need reliable evaluation and
experimentation to analyse their suitability for the wind turbine application
as a direct drive device. Such suitable application could be revolutionary due
its high performance, low cost and simple structural requirements. (Baywaters et
al, 2005)

Wind energy can make significant contribution to the electricity utility
network due to it being an inexpensive renewable energy source. However, two
issues need to be addressed first relating to the construction of the wind
power generator. The first one being the instability of the wind speed and the
second one, the rotating speed of the wind turbine which is low due to the
large diameter of the rotor blades. The technologies have been developed to
estimate the variable speed constant frequency to counter the instability of
the wind speed. The later issue was addressed by using conventional solution of
gear box to increase the speed which helps to reduce the size of generators.
Using gear box though comes with its cons such as more noise and vibrations,
high losses in gear drive due to gear box being a mechanical device, the need
of constant lubrication and maintenance of gear box.  Gear box’s cost is also high.

Direct driven variable speed
permanent magnet machines have various advantages such as such competitive cost
and possibility to eliminate the gear box from wind turbine structure. Energy
capture is increased in such application by using variable speed. The removal
of gearbox weight also leads to reduction of wind mill losses which results in
enhanced system efficiency.  Frequency of
periodic maintenance is also reduced thus reducing maintenance cost.

Although, large numbers of poles
are required to construct a generator due to low rotational speed; it is
necessary for the generator that it should be efficient naturally with a
competitive cost. To supply power to the grid, frequency converter is required
due to the variable speed scheme. According to (Fengxiang et al, 2005) small
pole pitch can be achieved by incorporating large pole numbers with permanent
magnets. A simple and effective generator construction is shown in figure 1 of
appendix 1 in the form of disc type axial flux configuration. The stator in the
figure shown is a toroidal wound accommodating rectangular coils which forms an
air gap winding. Permanent magnets are attached to the rotor disc located on
both side of stator.

According to (Spooner et al, 1996), the assembly of the permanent
magnet machine is the crucial problem during its construction. No strong forces
are present at the time of assembly as the assembly of the magnet is carried
out individually and iron parts are already located in the position in the
modern assembly practice of permanent magnet machines.

To reduce the assembly problems
of PM generators the modular construction is proposed by to (Spooner et al,
1996). The paper presented by to (Spooner et al, 1996) says that, for the large
grid connected wind turbines, direct coupled, permanent magnet, synchronous
with radial field and multipole machines can be used. The power rating could be
between 100 kW to 1 MW and pole numbers could be between 100 to 300. Employing
modular constructions help to reduce need of detail design, number of tools and
drawings. The modular assembly practice can be utilised in vast ranges of
machines. The standard ferrite magnet blocks are used in the rotor module,
whereas the stator module is formed by single rectangular coil embedded in
simple E-cores. The assembly of the magnetised parts can be arranged easily
which improves the efficiency of the machine with low reluctance. The multipole
permanent magnet is shown in figure 2 of appendix 1 whereas modular arrangement
of magnet is shown in figure 3 of appendix 1 which help to visualise the
difference.

 

 

4.0   Project management (Gant chart)

 

The above is the zoomed out full screen
capture of Smartsheet, a software I used to make my Gantt chart. Below is the
table of content that was used for Gannt chart and the  images showing the full Gantt chart.

Selecting
a project

10/10/17

10/14/17

5d

Completed

Background
reading for the project

10/16/17

10/22/17

7d

Completed

Project
brief

10/23/17

10/23/17

1d

Completed

Literature
review

10/23/17

11/06/17

15d

Completed

Submission
of ethics approval

11/13/17

11/13/17

1d

In
Progress

Gnat
chart/timeplan preparation

10/21/17

10/21/17

1d

Completed

Preliminary
analysis of the work

11/13/17

11/27/17

15d

Completed

Understanding
design requirements of Permanent magnet machines

11/20/17

12/04/17

15d

Completed

Familirising
with FEA concept and University FEA software

12/04/17

12/20/17

17d

In
Progress

Progress
report writing and referencing

12/20/17

01/08/18

20d

Completed

Submission
of progress report

01/15/18

01/15/18

1d

Completed

Design
of permanent magnet machine

01/24/18

02/12/18

20d

Not
Started

Simulation
of design in FEA software and its evaluation

02/12/18

03/05/18

22d

Not
Started

Critically
analyzing FEA results

03/05/18

03/19/18

15d

Not
Started

Completing
the final report

03/20/18

04/23/18

35d

Not
Started

Submission
of report

04/29/18

04/29/18

1d

Not
Started

Viva

05/11/18

05/11/18

1d

Not
Started

 

The above 3 images
combined horizontally make the full length Gannt chart.

 

The image below is
the full Gantt chart represented in a zoomed-out way to fit it on single page.

 

 

 

 

 

 

5.0   Progress of the work

The progress of the work shown
here is divided in to two parts,

1.     
Design
of permanent magnet machine

2.     
Finite
element analysis of the design

5.1 Design of permanent magnet
machine

During the study of permanent
magnet machine, various important design parameters were studied which is
incorporated in the design of the permanent magnet machine,

Rated
power of the machine- Velocity
of the wind speed and speed ration of driving shaft governs the rated output of
the generator. For this project work, minimum wind speed of 4 km/hour is
considered, the rpm produced by the shaft and output of the generator with
single phase connection will be calculated theoretically and evaluated during
FEA analysis of the design.

Number
of phases and poles- Number
of stator poles decide the number of phases in the machine. The thumb rule is
the number of stator poles are twice than number of phases. It has been found
that during research, torque ripple increases with small numbers of phases whereas
cogging torque reduces with large pole numbers. Considering these constraints,
three-phase machine is selected. By using electrical engineering handbook by
(Chen, 2004), 24 number of stator poles are selected to reduce the torque
ripples. The rotor pole is selected considering the relation between the rotor
and stator.

Frame
size- Dimension for all
electrical machines are freeze by International Electro-Technical Council known
as IEC, which comply the ISO regulations. The stator and rotor ratio selected
at this moment is 1:16 but it may change during designing of the Permanent
magnet motor depending upon the need. The structure size is yet to be finalized
although preliminary selection of the ratio fixes the frame structure.

Air
gap- The probability of cogging
torque increases due to use of permanent magnets therefore to reduce the same
and to increase the flux density air gap will be limited to a range of 0.5 to
1.0 mm.

Machine
specification- design of permanent magnet
machine is ongoing, and all the parameters are not fixed yet. Therefore a  tentative specification of permanent magnet
rotor is given below based on selection through engineering handbook and ratio,
just a note, below specification might change depending on the design
requirements,

Table
1: Initial specification of permanent magnet
machine

No

Parameters

Value

1

Rating

3000 W

2

Stator
poles

24

3

Magnet
poles

8

4

Phases

3

5

Poles
per phase

8

6

Length
of air gap

0.5 to
1.0 mm

7

Stator
diameter

0.16 m

8

Rotor
diameter

0.1 m

9

Length
of magnet

0.015 m

10

Length
of back iron

0.016 m

Based on initial specification of
permanent magnet machine, initial CAD model is generated which shown in figure
4 of appendix 1.

5.3 Finite element analysis

The design of PM machines will be
validated in FEA (Finite Element Analysis) software available in the university
such as Hyperworks 2017.2 or any other used in the university. The FEA software
is a powerful tool which help to analyse the design and allows necessary
changes before actual production and assembly. Various scenarios can be
simulated to check the performance of the PM machine.

In this project work, FEA will be
used to check the designed structure of the machine, excitation of the rotor,
material properties and torque produced due to different rotor position as well
as wind current. The step by step approach will be used to find solution of
continuum problem during FEA analysis; for example, elements are created by
dividing the continuum region by using different shapes of elements. It may be
possible that different shapes of element produce similar solution for the
continuum. It has been found during familiarization of software that it is
quickly possible to express material properties, constraints and excitation
although it is comparatively difficult to express. Other important parameters
will be calculated by using solution of system equation, such as, electromagnetic
problems, Components of magnetic flux density are nodal unknowns. By using
these components torque, induction and several other electromagnetic parameters
will be calculated and compared with the design one.

Following assumptions are made to
determine distribution of magnetic field inside the machine. These assumptions
are primary and may vary during actual simulation of the design,

1.     
Since
the magnetic field outside the status stamping is almost negligible hence the
magnetic vector potential line of outer periphery of the status stamping is
treated as zero

2.     
Hysteresis
effects are neglected as magnetic material is isotropic for stator and rotor
stampings

3.     
Components
of Z- directions are Current density (J) and magnetic vector potential (A)

4.     
Distribution
of magnetic field along the generator’s axial direction inside the generator is
constant

5.     
End
effects are considered to be zero

 

6.0   Summary and conclusion

The progress report includes
brief overview of permanent magnet machine with its application in wind
turbine, benefits of the same if used in the wind turbines followed by aim,
objectives and literature review with primarily emphasis on construction,
assembly and capacity of permanent magnet. Project management section shows
gnat chart in detail along with its completion status. Progress report on the
other hand shows the completed work so far in design part as well as future
considerations and assumptions for FEA.

Initial design specification for
the PM machine is completed, along with initial CAD drawing for the same.
Detail design procedure is in process and it will be completed by end of week
8. Study of FEA software by using similar case studies have been carried out.
Once the final design of the PM machine is completed then CAD modelling and FEA
simulation will commence which is around start of week 9. Any alteration
required in the design will be carried out considering the results of FEA.
Comparison of initial and final design along with FEA justification will be
provided.

In conclusion permanent magnet
motor when used for wind power reduces carbon emission as wind energy is
renewable energy and this model of work can be an efficient solution. Also with
developing technologies this method might also become more efficient and
cheaper.  All in all my project is a
little behind due to some uncertainties about some design aspects due to my ill
health during this semester but I will catch up and complete it on time in the
coming semester.

 

 

References

Aleksashkin, A. and Mikkola, A.
(2008). Literature review on permanent magnet generators design and dynamic
behaviour. Lappeenranta: Lappeenranta University of Technology, p.1-11.

Bywaters, G., John, V., Lynch,
J., Mattila, P., Norton, G., Stowell, J., Salata, M., Labath, O., Chertok A.,
Hablanian, D., April 12, 2001 to January 31, 2005, “Northern Power Systems Wind
PACT Drive Train Alternative Design Study Report”.

Karthikeyan, V and Thulasiyammal,
C. (2016). Design of Permanent Magnet Generator for Direct Driven Vertical Axis
Wind Turbine. International journal of innovative technology and research. 4
(2), pp 2794-2795.

Rizk, J., Nagrial, M., 2000.
“Design of permanent-magnet generators for wind turbines”, Power Electronics
and Motion Control Conference, Proceedings, IPEMC 2000, The Third
International, 1, p. 208-212.

Spooner, E., Williamson, A.C.,
Catto, G., 1996, “Modular design of permanent-magnet generators for wind
turbines”, Electric Power Applications, 143(5), pp. 388-395.

Wang Fengxiang, Bai Jianlong, Hou
Qingming, Pan Jian, 2005, “Design features of low speed permanent magnet
generator direct driven by wind turbine”, Electrical Machines and Systems, 2005.
ICEMS 2005. Proceedings of the Eighth International Conference, 2, pp.
1017-1020.

Yearbook.enerdata.net. (2018).
World Power consumption | Electricity consumption | Enerdata. online
Available at:
https://yearbook.enerdata.net/electricity/electricity-domestic-consumption-data.html
Accessed 6 Jan. 2018.

 

 

 

 

Appendices

Appendix 1- Figures and drawings

Figure
1: Air
gap windings in axial flux permanent magnet (Fengxiang et al, 2005)

Figure
2: Permanent
magnet rotor with multipoles (Spooner et al, 1996)

Figure
3: Modular
assembly of multipole permanent magnet rotor (Spooner et al, 1996)

Figure 4: Initial CAD model of
permanent magnet machine

 

 

 

x

Hi!
I'm Mack!

Would you like to get a custom essay? How about receiving a customized one?

Check it out