Energy Harvesting Based on Magnetic Dispersion for Three-Phase Power System

doi:10.4236/epe.2013.53B005

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Energy and Power Engineering, 2013, 5, 20-23

doi:10.4236/epe.2013.53B005 Published Online May 2013 (http://www.scirp.org/journal/epe)

Energy Harvesting Based on Magnetic Dispersion for

Three-Phase Power System

Tarcisio Oliveira de Moraes Júnior, Yuri Percy Molina Rodriguez, Ewerton Cleudson de Sousa Melo,

Maraiza Prescila dos Santos, Cleonilson Protásio de Souza

Federal Institute of Paraíba - IFPB, Cajazeiras, Brazil

Department of Electrical Engineering, Federal University of Paraíba - UFPB, João Pessoa, Brazil

Email: [email protected], {molina.rodriguez}{protasio}{maraiza.santos}{ewerton}@cear.ufpb.br

Received 2013

ABSTRACT

This paper presents a comparative study on Magnetic-Dispersion based Energy Harvesting Systems (MD-EHS) on

electrical conductors that supply power for a three-phase AC motor. It introduces two MD-EHS which are based on

magnetic cores of different material, named, nanocrystalline, ferrite and iron powder. The first one consists of harvest-

ing energy from magnetic flux through three symmetrical magnetic cores installed on each power conductors of a

three-phase AC motor. The second one consists of a single magnetic core for harvesting energy from magnetic flux of

only one of these conductors. Both ones have an AC/DC converter and a variable resistor based load. Experimental re-

sults have agreed with the theoretical analysis and show that the first proposed MD-EHS is capable of supplying 14

times more energy than the second MD-EHS, considering nanocrystalline cores and phase current of 3 A, and 7.5 times

more energy, considering ferrite cores and phase current of 9 A. Such energy can be applied to various low-power de-

vices, especially in wireless sensor network.

Keywords: Energy Harvesting; Magnetic Dispersion; Magnetic Cores

1. Introduction

Energy Harvesting is the process of capturing small

amounts of energy from energy sources available in en-

vironment, for instance: thermal, solar, mechanical,

magnetic induction, and others, and it is specially applied

in supplying energy to low-power devices particularly

those from wireless sensor networks. Energy harvesting

system based on magnetic induction is receiving consid-

erable attention since it is also applicable in measuring

variable in power lines.

An example of application of energy harvesting by

magnetic induction can be seen in [1] in which a system

composed basically of a magnetic flux device is capable

of transmitting to a base station the values of temperature

variations of the power line where itself is installed. In [2]

is proposed a system to harvest energy from electrostatic

field created between a power line and the ground. Ex-

perimental results have shown that the system can har-

vest 16 mW. In [3] was studied an energy harvester

based on magnetic induction on power line using a sim-

ple circuit model to validate the obtained theoretical re-

sults. As a result, 1mW of power was achieved consider-

ing air-core and 6.32 mW considering an iron core from

a magnetic field of 21.2 uT. Recently, in [4] it was stud-

ied a tube shaped energy harvester from power lines

where the power conditioning circuit is constraint for

constant voltage. As a result, the circuit efficiency does

influence the level of its output voltage. For constant

output power, the voltage level of the power conditioning

circuit decreases while the voltage of the transmission

line increases.

In this work, it is presented a comparative study on

Magnetic-Dispersion based Energy Harvesting Systems

(MD-EHS) on electrical conductors that supply power

for a three-phase AC motor. It was developed two MD-

EHS’s which are based on magnetic cores of different

material, named, nanocrystalline, ferrite and iron powder.

The first one, called 3F-MD-EHS, consists of harvesting

energy from magnetic flux through three symmetrical

magnetic cores installed on each power conductors of a

three-phase AC motor. The second one, called 1F-MD-

EHS, consists of a single magnetic core for harvesting

energy from magnetic flux of only one of these conduc-

tors.

This work is organized as follows: Section II describes

the essential theory of magnetic field regarding the cores

specifications, Section III shows the experimental analy-

sis, Section IV, the experimental results, and Section V,

the main conclusions.

T. O. de M. JÚNIOR ET AL. 21

2. Magnetic Field Theory

According to Ampere's law, the magnetic flux density at

a given distance r from a infinitely long conductor car-

rying an alternating current with a peak amplitude I and

frequency ω is given by:

sin( )







 (1)

where B is the magnetic flux density in a distance r of the

conductor and µm is the magnetic permeability of the

material between the conductor and the point r.

Figure 1 shows a laminated core on the power con-

ductor in a transversal way which the proposed MD-

EHS’s are based on. This core provides the magnetic

path for the magnetic flux and consists of about 50 thin

strips that are electrically separated by a thin layer of

insulating material. A coin, not shown in the figure, is on

the laminated core and is where the inducted voltage

takes place.

Based on Figure 1, the concatenated magnetic flux,

across the laminated core, with sectional area A, is given

by:

BdA



 (2)

where

dA wdr (3)

Substituting (1) and (3) in (2), it is obtained:

sin( )

It dr





 (4)

which can be reduced as follows:

()ln

Isent wrh















(5)

where



: magnetic flux of the magnetic L-th strip of

the core (where 0 < L < NL, NL = number of core strips)

rimary

conductor

Figure 1. Laminated cor e on a power conductor.

and

r is the radius of the L-th strip.

Concern the magnetic flux into the insulating material

between the laminated core strips, it is obtained from a

similar way and it is obtained:

0()ln

Isent wrS

















(6)

where

P: magnetic flux of the magnetic P-th strip of the

core (where 0 < P < NL-1) and rP is the radius of the P-th

strip.

Considering now that is a coin wounds around the core

with N2 turns. In this way, the output voltage of coin ter-

minals, according to Faraday's Law, is expressed as:



 (7)

where T



is the total magnetic flux. T



can be ob-

tained by the summation of the magnetic flux through the

magnetic and insulating blades:

Ln Pn

dd d

dt dtdt













(8)

where:

cos() ln

Itw

dt r

 

















(9)

0cos()ln

Itw

dt r

 

















(10)

To obtain theoretical results, it was considered as pa-

rameters the core dimensions: w, h, S, and r1 (internal

radius), as shown in Figure 1.

3. Experimental Study

In order to design the proposed MD-EHS, it was used

magnetic cores of three different materials: iron powder,

ferrite and nanocrystalline. The first proposed MD-EHS,

called 3F-MD-EHS, consists of harvesting energy from

magnetic flux through three symmetrical magnetic cores

installed on each power conductors of a direct start

three-phase AC motor, as can be seen in Figure 2.

In Figure 3, it is shown the power conditioning cir-

cuits (PCC) for the 3F-MD-EHS and in Figure 4 it is

shown for the 1F-MD-EHS.

The second proposed MD-EHS, called 1F-MD-EHS,

consists of a single magnetic core for harvesting energy

from magnetic flux of only one of these conductors.

It was carried out several experiments considering

cores of iron powder, ferrite and nanocrystalline and load

values, Rv, ranging from 10  up to 10 k. In all ex-

periments, the phase current of each conductor is 3 A for

the nanocrystalline cores, 9 A for ferrite and 12 A for

iron powder. The main parameters of the used cores are

described in Table 1.

T. O. de M. JÚNIOR ET AL.

Motor

mmetrical Cores

PCC

Figure 2. 3F-MD-EHS.

Motor

Source

380 V 60 Hz

3PH

680uF

XSC1

Ext Trig

_+_

Figure 3. Power conditioning circuit of the 3F-MD-EHS.

Motor

Source

380 V 60 Hz

3PH

680uF

XSC1

Ext Trig

_+_

Figure 4. Power conditioning circuit of the 1F-MD-EHS.

4. Experimental Results

After performing experiments considering the different

cores and the set of values of Rv, it was possible to obtain

the maximum obtained power and the voltages values.

The best results are described in Tables 2 and 3 and the

results considering the variations of Rv can be seen in

Figure 5 for the 3F-MD-EHS and Figure 6 for the 1F-

MD-EHS showing the power obtained for each value of

the load, Rv.

Table 1. Parameters of the used cores.

Core’s Parameters

Material w

[mm]

[mm] S r



Ferrite 8 4.2 6.85 0.00062300

Nanocrystalline10.35 4.4 22.5 0.00061000000

Iron Powder 18 11.3 12.05 0.000675

Table 2. Experimental results from 3F-MD-EHS.

3F-MD-EHS

Material V

[mV]

[mA]

[mW]

[]

[Arms]

Ferrite 560 11.3 6.3 50 3.0

Nanocrystalline 374 37.4 14 10 9.0

Iron Powder 5.7 0.57 0.0032 10 12.0

Table 3. Experimental results from 1F-MD-EHS.

1F-MD-EHS

Material V

[mV]

[mA]

[mW]

[]

[Arms]

Ferrite 310 4.6 1.5 70 3.0

Nanocrystalline 602 1.5 0.9 400 9.0

Iron Powder 18.5 1.85 0.034 10 12.0

50100 150 200 250 300

8x 10

-3

Load (Ohms)

P ower (W )

Ferrite

50100 150 200 250 300

0.005

0.01

0.015

0.02

Load (Ohms)

P ower (W)

Results first system

Nanocrystalline

50100 150 200 250 300

4x 10

-6

Load (Ohms)

P ower (W)

Iron Powder

Figure 5. Power levels – first system.

T. O. de M. JÚNIOR ET AL.

50 100150 200 250300 350 400

2x 10

-3

Load (Ohm s)

Power (W)

Ferrite

100 200 300400 500 600 700 800 9001000

0. 5

1x 10

-3

Load (Ohm s)

Power (W)

Res ul t s second system

Nanocrystalline

20 406080100120140

4x 10

-5

Load (Ohm s)

Pow er (W)

Iron P owder

Figure 6. Power levels – second system.

5. Conclusions

In this work, it was presented two proposed Magnetic-

Dispersion based Energy Harvesting Systems, called

3F-MD-EHS and 1F-MD-EHS, where the former works

on three phase conductors and the latter on one phase

conductor. Both are based on magnetic cores of different

material, named, nanocrystalline, ferrite and iron powder.

The obtained experimental results have shown that, con-

sidering the 3F-MD-EHS, it was capable of harvesting up

to 14 mW at a load of 10  for a nanocrystalline core

with 3 A RMS current on the power line; up to 6.3 mW

at a load of 50  for a ferrite cores with 9 A RMS current

on the power line; and up to 3.2 W at a load of 10 for

a core of iron powder with 12 A RMS current. Consider-

ing the 1F-MD-EHS, it was capable of harvesting up to

0.9 mW at a load of 400  for the nanocrystalline core

with 3 A RMS current on the power line; up to 1.5 mW

at a load of 70  for ferrite cores with 9 A RMS current

on the power line, and up to 34 W for a load of 10  for

an iron powder core with 12 A current on the power line.

In this way, it can be observed that the power harvested

from the nanocrystalline core 3F-MD-EHS is 14 times

higher than the nanocrystalline core 1F-MD-EHS and 7.5

times higher considering ferrite core. However, consid-

ering iron powder cores, the obtained power of the

3F-MD- EHS was 10 times less than in the 1F-MD-EHS.

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