M. H. Mohammadi, M. Poshtan
Department of Electrical & Computer Engineering
American University in Dubai
Dubai, U.A.E
1
1.
Introduction
4.
PM Material Selection
Grade & Size of Chosen PM
Generator Design Structure
5.
Feasibility Study of Solenoid
2.
3.
6.
Test 1, Test 2, Test 3
Generator Prototype Comparison
7. Power Charging Circuit
8. Application: Vision Stick
Conclusions
Question Session
9.
10.
2


Renewable energy source projects require
government & multinational company investments
US Residential Sector = 19% of US Energy Use
[1]
◦ Widespread use of electronic devices (e.g. mobile
phones, music players, tablets, …)
◦ Involve common people to self-generate power

Aim for an energy-aware society toward a more
sustainable future
3
Basis on Faraday’s
Law of Induction
e = – N dϕ/dt
Linear AC Synchronous Generator
Power Generation
Optimization:
 Magnet Material
 Magnet Shape
 Solenoid Wire
Thickness
 Number of Turns
4
Common Magnet Material Properties
[4]
BHmax
Flux Density
Coercive
(kJ/m3)
(mT)
Force (Hc)
Ceramic
26
100
High
Alnico
42
130
Low
SmCo
208
350
High
NdFeB
306
450
High
Material
2nd Quadrant of Hysteresis Curve [3]
Sintered NdFeB Magnet Grades [2]

Operate PM for:
◦ High magnetic strength
◦ Portable charging
◦ Optimum flux linkage
Grade
Br
(T)
Hcb
(kA/m)
BHmax
(kJ/m3)
Density
(kg/m3)
Max Working
Temp. (°C)
N35
N38
N40
N42
N45
N48
N50
N52
1.18
1.22
1.25
1.28
1.32
1.38
1.40
1.44
867.4
899.2
923.1
923.1
875.4
835.6
795.8
835.6
278.5
302.4
318.3
334.2
358.1
382.0
397.9
413.8
7400
7400
7500
7500
7600
7700
7800
7800
80
80
80
80
80
80
80
80
5
Up: Different
Magnet Shapes
Left: Comparison
of Magnet
Strengths
6

Constant structure for solenoid design

Cylindrical Structure (12cm long)
◦ Insulation paper material
◦ 2cm of wire wrapping space
◦ 2.1cm of tube diameter
7
Solenoid parameters:
 Wire diameter
◦ Tests 1 & 2

Number of turns
◦ Test 3
Design criteria:
 5V RMS output
 Shaking frequency
> 5Hz
Direct Relationship between Total Wire Resistance & Number of Turns
8

Constant Parameters:
◦ Magnet 1 (NdFeB Cylindrical)
AC Voltage Sample Waveform
◦ Generator structure
◦ 4 different manual shaking frequencies
 Low Frequency (LF) range: 0 to 5Hz
 Medium–Low Frequency (MedLF): 6 to 10Hz
 Medium–High Frequency (MedHF): 11 to 15Hz
 High Frequency (HF): 16 to 20Hz

Variable Parameter:
◦ Solenoid wire diameter (15 sizes)
 From 0.10mm to 0.85mm in 0.05mm step
increments (approx.)
9
Densities for
MedHF freq:
 Voltage-Turn:
4.50mV/trn

Current-Turn:

Power-Turn:
5.00mA/trn
0.90mW/trn
Power-Turn Density in Test 1
10

Same parameters as Test 1, except
◦ Magnet 2 (NdFeB Triple Ring)
Voltage-Turn Density in Test 2
Current-Turn Density in Test 2
11
Densities for
MedHF freq:
 Voltage-Turn:
8.00mV/trn

Current-Turn:

Power-Turn:
8.00mA/trn
2.00mW/trn
Power-Turn Density in Test 2
12

Constant Parameters:
◦
◦
◦
◦

Magnet 2 (NdFeB Triple Ring)
Solenoid wire diameter (0.28mm)
Generator structure
4 different manual shaking frequencies
 Low Frequency (LF) range: 0 to 5Hz
 Medium–Low Frequency (MedLF): 6 to 10Hz
 Medium–High Frequency (MedHF): 11 to 15Hz
 High Frequency (HF): 16 to 20Hz
Variable Parameter:
◦ Solenoid number of turns
 1 Level = 2cm centered space = 65turns
13
1 Level for 0.28mm
wire diameter = 65 turns
Down: RMS Voltage
Generated in Test 3
Up: RMS Current
Generated in Test 3
14
Values for
Level 15 in
MedHF freq:
 NL Voltage:
7.0mV/trn

NL Current:

Power:
250.0mA/trn
1600.0mW
Power Generated in Test 3
Chosen Solenoid Parameters:
 Wire diameter: 0.28mm
 Number of turns: 975 turns
15
1
o
o
o
Power = 140 mW
Mass = 56 g
Power Mass Density = 2.5 mW/g
2
o
o
o
Power = 1600 mW
Mass = 150 g
Power Mass Density =10.7 mW/g
Prototype #2 is 4 times more
power-mass efficient
16

Match mech. shaking to e-charging time constant:
◦ Avg. shaking frequency: 5Hz
◦ Resistance of generator: 23Ohms
◦ Chosen Capacitance: 9.4mF (2x4.7mF)
Down: Oscilloscope Waveform
of Charging Voltage
Up: Power Charging Circuit
of 2000mAh Battery Supply
17
Senior Design Project
(3 members + supervisor)


Enables visually-impaired people to
navigate more easily and provides an
emergency help option
Winner of the ESREC13
Competition amongst 30 teams
18

Portable Generator
◦ Charge system batteries with designed LPMSG

Detection & Alert System
◦ Detects nearby objects & alerts user via vibration

Emergency System
(down)
◦ Automatically obtains GPS coordinates & sends “HELP”
SMS to emergency contact
Extra Features
 Automatic LED switching
(right)

Stick folding (down)
19

Emergency SMS
◦ Consumes: 260 mA
◦ Average Time Taken: 2 mins
◦ Charge Needed: 8.67 mAh

Portable Battery Supply
◦ Capacity: 2000 mAh
◦ On Full Battery Charge: Sends 230 SMS
◦ For 1 Extra SMS, Shake Generator for:
Max Time: 15 mins
Min Time: 10 mins
20


A portable Linear Synchronous PM Generator
(LPMSG) was power optimized to meet the required
specifications for charging electronic devices.
Improved power generation through:
◦ Stronger N52 grade NdFeB magnets
◦ Specifically-Designed magnetization directions
◦ Guiding magnetic flux through design iron core.
A squirrel-cage low reluctance core incorporates lower
losses compared to air.
21
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[1]
[2]
[3]
[4]
F. Bressand et al., “Wasted energy: How the US can reach its
energy productivity potential”, McKinsey Global Institute, pp. 67, June 2007.
Magnet Sales. Magnets. United Kingdom. 2013 [Online].
Available: http://www.magnetsales.co.uk
Shin-Etsu Chemical Co. Rare Earth Magnet Basics. 2007
[Online]. Available: http://www.shinetsu-rare-earth-magnet.jp/e/design/
Stephen P Beeby and Terence O'Donnell, "Electromagnetic
Energy Harvesting," in Energy Harvesting Tecnologies,
Shashank Priya and Daniel J Imman, Eds.: Springer.
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