Design of axial flux permanent magnet synchronous generators for a small scale hydro power stations

1. Proposed Design Models of Axial-Flux Permanent Magnet
Synchronous Generator for Small-Scale Hydro Power Generation
Unit
presented by
Mohamed Abdo Hussein Mohamed
supervisors
Prof. Hamdy A. Ashour Dr. Walid M. A. Ghoneim

2. 2
The main motivation behind this research is investigating the performance of axial field permanent
magnet synchronous generators in small scale hydropower stations which could be installed in existing
public facilities additional constructions or cost.
Motivation
Most electric power in the world are produced by low efficiency thermal power stations. Although,
hydraulic power stations could be alternatives. they suffer from lack of investments for several reasons.
Firstly, large-scale hydro power stations require expensive civil constructions such as dams and
reservoirs. secondly, climate change effects alter rivers and canals flowrates which disturb the power
stations production.
Problem definition

3. A complete small-scale hydro-power generation set is proposed where a simple Savonius turbine and
high efficiency axial field permanent magnet synchronous generators are presented.
3
1. Microsoft Excel
2. MATLAB
3. Ansys Maxwell 16.0
proposed solution
Utilized tools

4. Contents
introduction and background
proposed linear design steps
linear design validation
hydro power generation set design
conclusion and future work
4

5. Introduction and background
 A high percentage of total electric power is generated by conventional thermal
power stations.
 The efficiency of thermal power stations is low and They are not always
economically feasible.
design steps
validation
Application
Conclusion
Introduction
Global electricity production percentages in 2018 [1]
5

6. Introduction and background
 Hydropower generation plants could be alternatives
 Large scale power stations require Dams constructions
 Dams are expensive and they have environmental drawbacks.
 The climate change may decrease the hydro power generation of dams.
 Small scale power stations attract much attention in recent years because of its
simplicity and environmental conservation
6
design steps
validation
Application
Conclusion
Introduction

7. Introduction and background
 In 2018, Egypt produced 2832 MW from hydropower resources
 It accounted for just 5.1 % of the total installed capacity
Electric generated power in Egypt 2014-2017 [2]
7
design steps
validation
Application
Conclusion
Introduction

8. Introduction and background
 In 2012, Egypt has 374 wastewater treatment plants
 Waste water treatment plants (WWTPs) are public benefit processes
 Capital costs are required to purchase land, equipment, and plant
constructions.
 Operating expenses entailing consumption of energy and use of chemicals.
8
design steps
validation
Application
Conclusion
Introduction

9. Introduction and background
 Electric power generation sets are suggested to be installed in the outlet of plants
after the disinfection process.
 At this point, The treated water is safe and the flow rate is high enough to
produce power.
 This suggestion could provide financial profits for these plants.
Waste water treatment plant layout [3]
9
design steps
validation
Application
Conclusion
Introduction

10.  Water turbines
 The water turbines can classified into axial flow water turbines (AFWT) and cross
flow water turbines (CFWT).
 (AFWT) turbines have an axis of rotation parallel to the water current direction.
 (CFWT) turbines have an axis of rotation perpendicular to the water current
direction.
10
design steps
validation
Application
Conclusion
Introduction

11. Axial and cross flow water turbines structures [4]
(a)Inclined axis (b) Flat mooring (c) Rigid mooring (d) Darrreius
(e) Savonius (f) Helical
(g) in plane (H) H-helical
11
design steps
validation
Application
Conclusion
Introduction

12.  (CFWTS) have Advantages over (AFWTS) could be summarized into :
1. High power density in narrow channels.
2. Work in any direction of flow.
3. Cross flow turbines can be stacked up to form a multi stage turbine.
Single stage cross flow turbine [5] multistage stage cross flow turbine [5]
12
design steps
validation
Application
Conclusion
Introduction

13.  Rapid decreasing of permanent magnets costs encourages the designers to
prefer Permanent magnet synchronous generators.
 synchronous generators are classified into two groups axial and radial . In
conventional (PMSG), air-gap flux density is radial; in AFPMs, it is mainly axial.
RFPM layout [6] AFPM layout [6]
13
design steps
validation
Application
Conclusion
Introduction
Permanent magnet synchronous generators

14.  (AFPM) generator topology is ideal to design a multistage generator which
achieves any required output power.
 Higher number of poles makes the (AFPM) generators a suitable choice for Low
speed operations.
 (AFPM) generators are subjected to better cooling than their radial counterparts
Multistage AFPM machine [7]
14
design steps
validation
Application
Conclusion
Introduction

15.  Step1: (Basic variables defining)
Proposed linear design steps
Start
Set rated output
power,
Speed,
Voltage,
frequency and
number of
phases
Step 2
15
design steps
validation
Application
Conclusion
Introduction

16.  Step2: (poles and slots calculations)
 2𝑝 =
120 𝑓
𝑁𝑚
 Slot/pole combinations should eliminate cogging torque.
 A feasible region of slots/pole/phase between 0.25 and 0.5..
 It achieves the highest winding factor.
Calculate the
number of
poles
Step 3
Step 1
select the
number of
slots
Calculate
slots/pole/phase
Within
limits ?
Fractional
?
Y
N
Y
N
Proposed linear design steps
16
design steps
validation
Application
Conclusion
Introduction

17.  Step3: (permanent magnets calculations)
Proposed linear design steps
17
Y
N
Step 2
Is the
structure
cored ?
Step 3.2
Step 3.1 design steps
validation
Application
Conclusion
Introduction

18.  Step3.1 : (permanent magnets calculations of cored structures)
 𝑔 =
𝐿𝑚
𝑃𝑐
 𝐵𝑚 =
𝑃𝐶
𝑃𝐶+𝜇𝑟𝑒𝑐
𝐵𝑟
 𝐻𝑚 =
𝐵𝑚−𝐵𝑟
𝜇𝑟𝑒𝑐 𝜇𝑜
Choose
magnet
Step 4
Step 2
Set the
permanence
and air gap
length
Calculate PM
thickness
Magnet
flux density >
knee point
Define the
magnet’s
operating point
Y
N
Proposed linear design steps
18
design steps
validation
Application
Conclusion
Introduction

19.  Step3.2 : (permanent magnets calculations of coreless structures)
 𝑔𝑒𝑞 =
𝐿𝑚
𝑃𝑐
 𝐵𝑚 =
𝑃𝐶
𝑃𝐶+𝜇𝑟𝑒𝑐
𝐵𝑟
 𝐻𝑚 =
𝐵𝑚−𝐵𝑟
𝜇𝑟𝑒𝑐 𝜇𝑜
Choose
magnet
Step 4
Step 2
Set the
permanence
and PM
thickness
Calculate the
equivalent air
gap
Magnet
flux density >
knee point
Define the
magnet’s
operating point
Y
N
Proposed linear design steps
19
design steps
validation
Application
Conclusion
Introduction

20.  Step4: (Magnetic and electric loadings calculations)
 𝐵𝑔 =
∅g
𝐴𝑚
=
𝐾𝐿𝐵𝑟
1+ 𝐾𝑟
μr
𝑃𝑐
 𝐴 ≈
σ
𝐵
Set the
shear stress
value
Step 3
Calculate the
air gap
flux density
Calculate the
electric loading
Step 5
Proposed linear design steps
20
design steps
validation
Application
Conclusion
Introduction

21.  Step5: (Dimensions calculations)
 𝜆 =
𝐷𝑖
𝐷𝑜
 𝑃𝑜𝑢𝑡 = 𝑚 𝑘𝑝𝐸𝑝𝑘𝐼𝑝𝑘
 𝐸𝑝𝑘 = 𝐾𝑒 𝑁𝑝ℎ 𝐵𝑔
𝑓
𝑝
1 − λ𝟐
Do
2
 𝐼𝑝𝑘 = 𝐴 𝜋 𝐾𝑖
1+𝜆
2
𝐷𝑜
2 𝑚1 𝑁𝑝ℎ
Set the inner
to outer
diameter
ratio
Step 4
set
current and
power
waveform
constants
Calculate the
outer diameter,
number of turns
per phase
and inner
diameter
Step 6
Proposed linear design steps
21
design steps
validation
Application
Conclusion
Introduction

22.  Step6: (winding calculations)
 𝑛𝑐 =
𝑁𝑠
𝑚
(double layer winding)
 𝑛𝑐 =
𝑁𝑠
2 𝑚
(single layer winding)
 𝑆𝑎 =
𝐼𝑟𝑚𝑠
𝑎𝑤𝐽𝑎
 𝑁𝑐 =
𝑎𝑤𝑁𝑝ℎ
𝑛𝑐
Choose a
winding
topology
Step 5
Calculate the
number of
coils per
phase
Set the current
density and
number of parallel
wires
Step
6.1
Calculate Conductor cross
section area and diameter
conductor
diameter
≤1.5 mm
Y
N
Proposed linear design steps
22
Calculate the number of
conductors per coil
design steps
validation
Application
Conclusion
Introduction

23.  Step6.1: (winding calculations)
 𝐴𝑐𝑜𝑖𝑙 = 𝑆𝑎 𝑁𝑐
 𝐶𝑎𝑡 = 𝑔𝑒𝑞 − 𝑔
 𝐶𝑟𝑡 =
𝐴𝑐𝑜𝑖𝑙
𝐶𝑎𝑡
Step
6.1
Step 7
Calculate the coil side
cross sectional area
Y
Proposed linear design steps
23
Calculate the coil side
dimensions
Is the
structure
cored ?
N
design steps
validation
Application
Conclusion
Introduction

24.  Step7: (slot calculations)
 𝐴𝑠𝑙𝑜𝑡 =
𝑆𝑎 𝑁𝑐 𝑁𝑐𝑜𝑖𝑙𝑠𝑖𝑑𝑒𝑠
𝐾𝑐𝑢
 𝑡1𝑚𝑖𝑛 =
𝜋𝐷𝑖
𝑁𝑠
 𝑡1𝑚𝑎𝑥 =
𝜋𝐷𝑜
𝑁𝑠
 𝐶1 𝑚𝑖𝑛 = 𝑡1𝑚𝑖𝑛 − 𝑏11
 𝐶1 𝑚𝑎𝑥 = 𝑡1𝑚𝑎𝑥 − 𝑏11
 𝐵𝑡𝑚𝑎𝑥 = 𝐵𝑔
𝑡𝑚𝑖𝑛
𝐶𝑚𝑖𝑛
Calculate
Slot area
Step
6
Calculate
slot
pitches
Set the slot width
Step
8
Calculate
teeth widths
flux density
< saturation
limit
Calculate teeth
flux density
Calculate slot
height
Y
N
Proposed linear design steps
24
design steps
validation
Application
Conclusion
Introduction

25.  Step8: (Back iron calculations)
 ℎ𝑦𝑠 =
𝜋 𝐵𝑔 𝛼𝑖 𝐷𝑜 1+λ
4 𝑃 𝐵𝑐𝑠
 ℎ𝑦𝑟 =
𝜋 𝐵𝑔 𝐷𝑜 1+𝜆
4 𝑃 𝐵𝑐𝑟
 𝑃𝑣 =
𝑃𝑜𝑢𝑡
𝜋
4
𝐷𝑡𝑜𝑡
2 𝐿𝑡𝑜𝑡
Set the
maximum
flux density
in
rotor core
Step 7
Set the
maximum
flux density
in stator core
Calculate Stator
and
rotor cores
thicknesses
Step 9
Calculate the
power
density
Proposed linear design steps
25
design steps
validation
Application
Conclusion
Introduction

26.  Step9: (Losses and efficiency calculations)
 𝑅𝑝ℎ =
ρ (𝐿𝑝ℎ+π 𝐷𝑜)
𝑎𝑝𝑎𝑤 Sa
 𝑃𝑐𝑢 = 𝑚1 𝐼𝑟𝑚𝑠
2
𝑅𝑝ℎ
 𝑃𝑓𝑒 = 𝑘ℎ 𝑓𝐵α + 𝑘𝑒ℎ2𝑓2 𝐵2
 𝑃𝑓𝑟 = 0.06 𝐾𝑓𝑝 𝑚𝑟 𝑛
 η =
Pout
Pout+ Pf𝑒
+ Pcu+ Pm
Set the
conductor
resistivity
and length
Step 8
Calculate the
phase
resistance
and Joule
losses
Set the eddy
current and
hysteresis
constants
Step
10
Calculate the
core and
mechanical
losses
Calculate the
efficiency
Proposed linear design steps
26
design steps
validation
Application
Conclusion
Introduction

27.  Step10: (impedance and terminal voltage calculations)
 𝑋𝑠 = 𝑋1 + 𝑋𝑎
 𝑋1𝑠 =
4 𝜋 𝑓 𝜇𝑜𝐿𝑖 𝑁𝑝ℎ
2
𝑝 𝑞
ℎ11
3𝑏11
+
ℎ12+ℎ13+ℎ14
𝑏11
 𝑋𝑎 =
2 𝑚 𝜇𝑜 𝑓 𝑁𝑝ℎ
2
𝐾𝑤
2
(𝑅𝑜𝑢𝑡
2
−𝑅𝑖𝑛
2
)
𝑝2𝑔
 𝑍 = 𝑅𝑝ℎ
2
+ 𝑋𝑠
2
 𝑉𝑓𝑙 = 𝑉𝑛𝑙 − 𝐼 𝑍
Calculate the
winding
reactance
Step 9
Calculate the
impedance
and
phase
terminal
voltage
Step
11
PMSG equivalent circuit [14]
27
Proposed linear design steps
design steps
validation
Application
Conclusion
Introduction

28.  Step11: (Building a finite element model)
Step
10
Build FEM End
Proposed linear design steps
28
design steps
validation
Application
Conclusion
Introduction

29. Linear design Validation
 A case study, from published research paper [10] is used for design steps
validation
 A three phase single side slot-less axial flux machine is redesigned.
Case study :single sided slot less AFPM
Generator Layout
29
design steps
validation
Application
Conclusion
Introduction

30. Generator specifications for the case study (inputs)
Generator specifications
Output power (KW) 5
Slot fill factor 92
Air gap flux density (T) 0.44
Phase resistance 0.19
Magnet length (mm) 12
Slots number 24
Number of Poles 8
Speed (rpm) 1000
Phase induced voltage (V) 132
30
design steps
validation
Application
Conclusion
Introduction

31. Linear design Validation
 The generator specifications (Input variables) are used to redesign the case study
using the proposed design steps.
 The output dimensions of the analytical design steps are used to create a model
using FEM software.
 The focus in this case is to hold a comparison between the FE model and the
research paper regarding dimensions and active material.
31
design steps
validation
Application
Conclusion
Introduction

32. Linear design Validation
Generator model using FEM software
32
design steps
validation
Application
Conclusion
Introduction

33. Linear design Validation
Simulation results at full load Flux density magnitude spectrum
33
design steps
validation
Application
Conclusion
Introduction

34. Linear design Validation
Case study Validation using the research paper
Parameters Proposed Original
paper [10]
DEVIATION
%
Outer
Diameter
(mm)
239 250 -4.4
Axial length
(mm)
58 55 +5.17
Steel weight
(Kg)
7 6 +16
Copper
weight (Kg)
6.5 5 +30
Magnet
weight (Kg)
1.9 3 -36
Total weight
(Kg)
15.4 14 +10
Power to
weight
(W/Kg)
324 357 -9
34
design steps
validation
Application
Conclusion
Introduction

35. Linear design Validation
Case study Validation using the research paper
 The deviation percentages doesn’t exceed 10% for the total weight.
 The dimensions' deviation percentage doesn’t exceed 6%.
 The machine in [10] consumes 16% less steel and 30% less copper with higher
power to weight ratio.
 The machine based on the proposed linear design steps consumes 36% less
magnets which is the most expensive active material.
35
design steps
validation
Application
Conclusion
Introduction

36.  A complete hydro-power generation set will be deigned for a waste water
treatment plant
 Hydro power generation set consists of water turbine and electric generator
Hydro power generation set layout
36
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

37.  Turbine design
 Savonius rotor will be selected since it is simple in construction and design .
Generation
site data
design
equations
Turbine
dimensions
Q: flow rate
H: head
Vo :water velocity
LR: Turbine height
DR: Turbine diameter
37
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

38. Inputs
Mass flow rate Qm (kg/s) 500
volume flow rate
(m3/s)
Qv (m3/s) 0.5
Net head Hg (m) 1
Assumptions
Water density ρ (kg/m3) 1000
Power coefficient Cp 0.47
Aspect ratio α 1.5
Tip speed ratio λt 1.4
Outputs
Turbine power Ptur (Watt) 2303
Turbine height LR (m) 0.412
Turbine diameter DR (m) 0.275
Turbine speed nm (RPM) 429.54
Turbine deign parameters
38
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

39. Generator specifications (Inputs)
39
Generator specifications and restrictions
Output power P [Watt] 2300
Mechanical speed nm [rpm] 428
phase voltage V [V] 220
slots/ poles Ns/2P 48/16
Current density J [A/mm2] 6
Stacking factor 0.9
yokes and PM materials constraints (Nd Fe B )
Residual flux density Br[T] 1.1
Relative permeability μr 1.05
Maximum flux density in core Bcs,Bcr[T] 1.7
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

40.  Model (A):double-sided internal stator cored AFPMSG design
A three phase double-sided internal stator cored AFPM generator is analytically
designed.
The output dimensions of the analytical design are used to create a model using FEM
software package.
Double-sided internal stator cored AFPMSG exploded view [11]
40
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

41. Generator model using FEM software
41
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

42. Simulation results at full load
42
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

43. parameters Proposed
analytical
design
Maxwell 3D
model
DEVIATION % Maxwell
3D model Vers. Linear
analysis.
Phase voltage [V] 220 232.36 5.62
Phase Current [A] 3.48 3.72 6.90
Pout [Watt] 2303 2593.13 12.60
Efficiency Ƞ [%] 93.46 92.21 -1.34
 The deviation percentage does not exceed 13 % for all parameters.
43
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

44.  Model (B):double-sided internal stator coreless AFPMSG design
A three-phase double-sided internal stator coreless AFPM generatoris is analytically
designed.
The output dimensions of the analytical design are used to create a model using FEM
software package.
Double-sided internal stator coreless AFPMSG layout [12]
44
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

45. Generator model using FEM software
45
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

46. Simulation results at full load
46
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

47.  The deviation percentage does not exceed 16 % for several parameters.
parameters Proposed analytical
design
Maxwell 3D
model
Deviation%
Maxwell Vers.
Linear
Phase voltage [V] 220 250.51 13.87
Current [A] 3.48 4.01 15.23
Pout [Watt] 2303 3013.63 30.86
Efficiency Ƞ [%] 85.22 84.96 -0.31
47
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

48.  The cored generator topology drawbacks include the saturation in teeth tips,
steel laminations weight and manufacturing hardships.
 The coreless generator topology disadvantages are relating to the high
copper losses, permanent magnet and copper high consumption.
 Therefore, a suggestion of a new hybrid half cored half coreless machine with a
lower stacking factor is presented in model (C).
48
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

49.  Model (C):double-sided internal stator hybrid AFPMSG design
The hybrid generator in model (C) is identical to the cored generator in model (A)
except that the laminations stacking factor value which is decreased to 0.4.
Generator model using FEM software
49
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

50. Simulation results at full load 50
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

51.  Sensitivity analysis
 A sensitivity analysis is a tool – built in the FEM software .
 It identifies the influence of selected input variables on a predefined objective function .
 The magnet length and the number of turns per coil are selected as input design variables.
 The phase voltage amplitude is chosen as an objective function.
 Each input design variable is individually tuned and its effect on the phase voltage
amplitude is calculated
51
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

52.  Tuning the magnet axial thickness increases the phase voltage to 169.65 V
which is 22.88 % less than the required value.
 The permanent magnet is more expensive than steel and copper. So,
compensating the phase voltage by tuning the magnet thickness increase the
cost.
Induced voltage Versus magnet thickness
52
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

53.  Tuning the number of turns per coil achieves the required phase induced
voltage at (nc =93).
 Based on that, the hybrid machine is adapted by increasing the number of turns
per coil.
 It is the most effective and economical solution in compensating the poor
performance due to decreasing the stacking factor.
Induced voltage Versus number of turns per coil
53
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

54. 54
Hydro power generation set design
Parameter Model A
(Cored)
Model B
(Coreless)
Model C
(Hybrid)
Efficiency (%)
92.21 84.96 81.97
Armature Copper
Weight (kg): 1.92 3.84 3.24
Permanent
Magnet Weight
(kg):
1.72 3.49 1.72
Cores Steel
Weight (kg):
15.25 7.44 6.20
Total Weight (kg): 18.89 11.43 11.61
Power to weight
(W/kg) 137.27 263.65 199.71
design steps
validation
Application
Conclusion
Introduction

55.  Model (A) approximately achieves the required phase voltage, current and
output power but the teeth tips and heavy weight makes that model the most
complex.
 Model (B) efficiency is 84.96 % because of high copper losses.
 The hybrid generator in model (C) decreased the steel consumption with 55 %.
 Model (C) comprises the advantages of cored and coreless structures such as the
high efficiency and low active material consumption.
55
Hydro power generation set design
design steps
validation
Application
Conclusion
Introduction

56. Conclusion and future work
 Hydro power stations have advantages over conventional thermal ones including
high efficiency and sustainability
 Small scale hydro power stations are economical and environmentally friendly
because they could be installed in existing facilities such as waste water treatment
stations.
 (AFPMSGS) are suitable choice for Low speed applications because they can
accommodate a large number of poles.
 Multi-stage (AFPMSG) topology allows to achieve output power requirements.
56
design steps
validation
Application
Conclusion
Introduction

57.  A case study from a published research paper is redesigned using the analytical
design steps and simulated using FEM software package.
 Comparisons are held between FEA model and the published research
papers.
 They prove that the results have similarities with acceptable margin.
 A complete hydro-power generation set is presented as an application . Cored and
coreless machines are designed and simulated using FEA software package.
57
Conclusion and future work
design steps
validation
Application
Conclusion
Introduction

58.  A new hybrid half cored half coreless machine design with less stacking factor
is proposed to decrease active materials consumption using a sensitivity
analysis is assigned to enhance the performance.
 A comparison between the different machines is held considering the
consumption of active materials and cost.
 It concluded that the hybrid generator comprises the advantages of cored and
coreless structures such as the high efficiency and low active material
consumption.
58
Conclusion and future work
design steps
validation
Application
Conclusion
Introduction

59.  Optimization studies may be used to adapt weight, cost, power density and
cogging torque.
 The fault tolerance feature which is the machine immunity against failures
could be considered in the machine design by selecting (AFPM) modular
machines.
 Since the permanent magnets and windings insulation are sensitive to temperature
rise, a thermal model could be used to define hotspots and concisely select
the appropriate cooling method.
59
Conclusion and future work
design steps
validation
Application
Conclusion
Introduction

60. References
60
1. T. André, F. Appavou, A. Brown. G. Ellis, B. Epp, D. Gibb, F. Guerra, F. Joubert, R.
Kamara, B. Kondev, R. Levin, H. E. Murdock, J. L. Sawin K. Seyboth, J. Skeen, F.
Sverrisson and G. Wright“ Renewables Global Status Report ,” Renewable
Energy Policy network Agency, France, 2020
2. Egyptian electricity holding company annual report 2017 / 2018.
3. E. Ranieri, H. Levernez, P. Vega, G. Tchobanoglous. “An Examination of the
Factors Involved in Agricultural Reuse: Technologies, Regulatory and Social
Aspects,” Journal of Water Resource and Protection, May, 2011.
4. H. Canilho and C. Fael. “Velocity Field Analysis of a Channel Narrowed
by Spur-dikes to Maximize Power Output of In-stream Turbines,” Journal of
Sustainable Development of Energy, Water and Environment Systems, 2018.
5. N. I. Khan, M. T. Iqbal, M. Hinchey and V. Masek . “Performance of savonius
rotor as a water current turbine,” Journal of Ocean Technology, 2009.

61. References
61
6. M. Taylor, K. Danial, A. Ilas and E. young. “Renewable power generation
costs in 2014,”Interantional Renewable Energy Agency, January,2015
7. A. Mahmoudi, N. A. Rahim and W. P. Hew “Axial-flux permanent-magnet machine
modeling, design, simulation and analysis,” Scientific Research and Essays
journal, June, 2011
8. A. Llc, “Magnet Guide & Tutorial,” 2009.
9. J. Hendershot and T. Miller. Design of Brushless Permanent-Magnet Motors.
2nd edition. Oxford: Magna physics publications, 1994.
10. K. Sitapati and R. Krishnan, “Performance comparison of radial and axial field
permanent magne brushless machines” IEEE Transactions on Industrial
Applications., vol. 37, no. 5, pp. 1219-1226, Sept/Oct 2001

62. References
62
11. A. Parviainen, “Design of axial-flux permanent-magnet low-speed machines and
performance comparison between radial-flux and axial-flux machines,” PhD
Thesis,2005.
12. S. Javadi and M. Mirsalim “A Coreless Axial-Flux Permanent-Magnet Generator for
Automotive Applications.” IEEE transactions on magnetics, 2008

63.  There are 64 papers concerning axial field
permanent magnet synchronous generators were
being published according to IEEE xplorer search
engine from 1996 to 2019
 45 papers were published from 2010 to 2019
63
References

64. List of published papers
64
THE 8TH INTERNATIONAL CONFERENCE ON MODELING SIMULATION AND
APPLIED OPTIMIZATION (ICMSAO) – Bahrain 2019
[1] A Comprehensive Study of Proposed Linear Design Procedures for Low-Speed
Axial-Field PMSG.
[2] A Design of an Axial Field Permanent Magnet Generator for Small-Scale Water
Turbines –Focus on Stacking Factor Effects on Performance.
To be published:
Proposed Design Models of Axial-Flux Permanent Magnet Synchronous Generator for
Small-Scale Hydro Power Generation Unit

65. 65

66. Appendix (A): Permanent magnets shapes, advantages and
disadvantages
66
Permanent magnets shapes, advantages and disadvantages

67. Appendix (B): Magnetic operating point (Linearity check)
 In normal operation the magnet operates at a
flux below (∅r).
 The recovery is complete and reversible
provided that the operating point has not left the
linear part of the demagnetization curve.
 If the operating point is driven below the knee
point to the nonlinear part of the
demagnetization curve.
 The magnet will recover along a lower recoil line
with remnant flux loss. This loss is permanent
67
Permanent magnet demagnetization curve

68. Appendix (C): Shear stress
 The product of electric loading and magnetic
loading is the shear stress.
 If shear stress value increases, the outer
diameter will decrease
 𝑃𝑜𝑢𝑡 =
𝜋
2
𝑚
𝑚1
𝑘𝑤𝑘𝑖𝑘𝑝𝐵𝑔𝐴
𝑓
𝑝
η 1 − λ2 1+λ
2
𝐷𝑜
3
 This saves ferromagnetic materials in yokes,
but at the cost of increasing the magnets and
copper consumption
Shear stress selection guidelines
68

69. Appendix (D): current and power waveforms constants
Current and power waveforms constants
69

70. Appendix (E): windings topologies
AC machines windings layouts
AC machines windings hierarchy
70

71. Appendix (F): slot dimensions
Slot dimensions layout Teeth flux density spectrum
71

72. Appendix (G): Finite element model
 FEM solves the electromagnetic field
problems by meshing solid objects.
 It solves Maxwell equations in each of
them.
 Finite element analysis software is
used to validate the performance.
FEM meshing process
72