Indian Journal of Science and Technology, Vol 9(14), DOI: 10.17485/ijst/2016/v9i14/91101, April 2016
ISSN (Print) : 0974-6846
ISSN (Online) : 0974-5645
Reliability Analysis of Permanent Magnet and
Air-gap Flux Density of Spoke-type IPMSM for
Driving Cooling Fans
Yun-Soo Kim1, Jun-Young Kim2, Dong-Woo Kang3* and Ju Lee1
Department of Electrical Engineering, Hanyang University, Seoul 133-791, Korea
Automotive Components R&D Department, Daedong Movel System Inc., Gyeonggi 429-851, Korea
3
Department of Electrical Energy Engineering, Keimyung University, Daegu 704-701, Korea;
Sanghyuk.Lee@xjtlu.edu.cn
1
2
Abstract
One of the key electrical components in a car, a motor has been actively studied based on its reliability. In recent years,
as the proportion of the motor has increased in a car, development of the motor with a high output and a low price has
been required. IPMSM can cause a high torque per unit current by using a reluctance torque generated from the difference
in the magnetic resistance, which is suitable for the motor which requires a high output. In particular, since the spoketype IPMSM with a concentrated flux structure can utilize non-rare earth metal-based ferrite magnets which are cheaper
than rare earth metal-based permanent magnets such as neodymium, this can lower the motor price. In this paper, we
study driving characteristics by analyzing the magnetic flux density and cogging torque that causes noise and vibration in
accordance with the rotor shapes (Magnet, Rib) of the spoke-type IPMSM.
Keywords: Engine Cooling Fan, Fan Motor, Ferrite Magnet, Interior Permanent Magnet System Synchronous Motor
(IPMSM), Spoke Type, Vehicle Motor
1. Introduction
These days, rare-earth resources have been used frequently
in electrical and electronic equipments1. Rare earth
metal-based permanent magnets are used to improve efficiency at low speed. Until recently, there have been some
issues surrounding the raw materials used in the rare
earth-based magnets, such as increased price and limited export of rare earth based-magnets. Since rare earth
metal-based magnets are still expensive and the prices are
unstable, they may not be desirable for motors. Therefore,
it is important to develop IPMSM, which does not use
rare metal-based magnets2. Among other IPMSMs, the
spoke-type IPMSM with a high reluctance torque and
concentrated flux structure especially has a high torque
per unit volume The spoke-type IPMSM has been studied
for applications where a high torque is required. However,
*Author for correspondence
the spoke-type IPMSM has some problems. First, it causes
local demagnetization at the edge of the permanent magnet by an external magnetic field. Secondly, because of
the distortion of the air-gap magnetic flux density distortion, cogging torque increases, thereby decreasing motor
performance, changing operation regions and generation
noise and vibration3,4.
Structurally, the spoke-type IPMSM may have Rib
structure in the outermost of a rotor. This Rib structure of the rotor affects the operation range, properties
and safety factor of the motor. In addition, it is related
to demagnetization phenomenon that affects the motor
characteristics5. This paper investigated the impact of airgap magnetic density on cogging torque in accordance
with the rotor shapes (magnet, rib) of the spoke-type
IPMSM and interpreted demagnetization of ferrite
magnets.
Figure 2. Air-gap flux density corresponding to the thickness of the permanent magnet.
In case of the rib, the spoke-type IPMSM may have a rib structure in the outermost of the rotor. The rib stru
affects the operation range, properties and safety factor of the motor. In addition, it is related to demagneti
Reliability Analysis of Permanent Magnet and Air-gap
Fluxthat
Density
IPMSM5.for
Driving
Cooling
phenomenon
affectsof
theSpoke-type
motor characteristics
Figure
3 shows
a basic Fans
model and Table 1 shows the specifica
Figure 4 shows the shape variables for the width and rib of the permanent magnet.
2. Air-gap Magnetic Flux Density in
accordance with Rotor Shapes
In this chapter, we set up a rib and a permanent ­magnetics
as variables to analyze the characteristics of motors in
accordance with rotor shapes of the spoke-type IPMSM.
Figures 1 and 2 show the effect of changes in the width
and thickness of the permanent magnet has on the airgap flux. By the way the result of analysis by arbitrarily
specifies the size of the magnet. Since the width of the
Figure 3. Spoke-type
IPMSM model.
Figure 3. Spoke-type
IPMSM model.
permanent magnet has more effects on the motor output
Table 1. Specification
and is more advantageous for increasing magnetic
flux of analysis model
Table 1. Specification
of analysisValue
model
Items
per unit volume than the thickness, we only designated
Output
250 [W] Value
Items
the width as a variable.
DC
link
voltage
13.5
[V]250 [W]
Output
In case of the rib, the spoke-type IPMSM may have a
Rated speed
2000 [RPM]
DC link voltage
13.5 [V]
rib structure in the outermost of the rotor. The rib strucRated Torque
1.2 [Nm]
ture affects the operation range, properties and safety
Rated speed
2000 [RPM]
Number of poles
6 [poles]
factor of the motor. In addition, it is related to demagnetiRated
Torque
1.2 [Nm]
Number of phases
3 [phase]
zation phenomenon that affects the motor characteristics5.
NumberStack
of length
poles
25 [mm]6 [poles]
Figure 3 shows a basic model and Table 1 shows
the specimagnets
relative to the surfaceNumber
of the rotor
are
constant6. Therefore,
of phases
3selected
[phase]an appropriate length for air
Air-gap
length
0.5 we
[mm]
consideration
of the loading ratio and set up the output required for loading vehicle engine cooling fan and the ma
fications. Figure 4 shows the shape variables for
the width
Stack length
25 [mm]
value of output phase voltage in accordance
with an inverter PWM modulation
system. In addition, we minimi
and rib of the permanent magnet.
stack
length to
reduce the inertia for driving the fan and designed in accordance with rated speed.
2.1 Model
Properties
Air-gap length
2.1 Model Properties
[mm]
The analytical model was designed by applying numerical analysis method such as a finite element method t
Variables
of spoke-type
Rotor Shapes
design2.2directly.
In the
IPMSM, the permanent magnets are inserted at both ends of one pole of the roto
present symmetrically and the magnetic pole consists of core surface of the rotor between the permanent ma
Therefore, this structure can increase air-gap magnetic flux density by increasing the cross-sectional area of the perm
The analytical model was designed by applying numerical
analysis method such as a finite element method to the
Figure 4. Shape variables
of a permanent
magnet
and Rib.of a permanent magnet and Rib.
Figure
4. Shape
variables
Table 2. Design Parameters
Table 2. Design Parameters
Variable
Variable
Figure 1. Air-gap flux density in accordance with the width of the permanent magnet.
Range
Range
Step Step Unit
Unit
mm
mm
Figure 1. Air-gap flux density in accordance with the
Width
14.5~
~ 15.0
0.1 0.1
MagneticMagnetic
Width
14.5
15.0
Rib Thickness
0.82 ~ 1.52
0.1
width of the permanent magnet.
0.82 ~ 1.52
Figure 1. Air-gap flux density in accordance withRib
theThickness
width of the permanent
magnet. 0.1
mm
mm
As shown in Figure 4, we attempted to analyze the impact on the air-gap flux density through changes in the w
permanent magnets, a design variable of the magnetic circuit of the spoke-type IPMSM and rib through which.
design directly. In the spoke-type IPMSM, the permanent
flux density corresponding to the thickness of the
3. Cogging
Characteristics
in Accordance
with
the of
Air-gap
Flux Density
magnetsTorque
are inserted
at both
ends of one
pole
the rotor
In this section, we investigated
the
characteristics
of
cogging
torque
in
accordance
with
distribution
and present symmetrically and the magnetic pole con- of air-gap m
flux density. For this purpose, we analyzed dimensional changes in permanent magnetic which are the design varia
sists
surface
of the
rotorofbetween
the permanent
magnetic circuit from the
dataofofcore
the same
rotors and
the effects
the rib structure
on the air-gap magnetic flux
after analyzing the characteristics
essential
to the design
ofstructure
the spoke-type
IPMSM.
Afterwards,
we investigate the
magnets.
Therefore,
this
can
increase
air-gap
permanentcharacteristics
magnet. of the spoke-type IPMSM using the finite element method.
magnetic flux density by increasing the cross-sectional
3.1 Characteristicsarea
of theof
Magnetic
Circuit of themagnets
Spoke-typerelative
IPMSM to the surface of
the
permanent
rib, the spoke-type
IPMSM
mayflux
have
a rib corresponding
structure in thetooutermost
of the
rotor.
The
ribmagnet.
structure
Figure
2. Air-gap
density
thereason
thickness
of the
permanent
The
for analyzing
the
characteristics
of the
6 magnetic circuit of the IPMSM with a permanent magne
the rotor
constant
. Therefore,
appro-magnets than a c
on range, properties
safety factor
of the motor.
In know
addition,
to are
demagnetization
Figure and
2. Air-gap
flux density
corresponding
to size
theitof is
the
the related
air-gap
magnetic
flux.
The spoke-type
IPMSMwe
has selected
used more an
permanent
5
bar-typeand
IPMSM.
However,
a large
magnetic
flux
can be in
created
in the air-gap despite
using
less permanent magne
affects the motor
characteristics
.
Figure
3
shows
a
basic
model
Table
1
shows
the
specifications.
priate
length
for
air-gap
consideration
of
the
loading
thickness
of
the
permanent
magnet.
In case of the rib, the spoke-type IPMSM
may have a rib structure in the outermost of the rotor. The rib structure
performance of the permanent magnet and reducing the cross-sectional area of the air-gap can lead to a large magne
shape variables
for
the
width
and
rib
of
the
permanent
magnet.
affects the operation range, properties and insafety
factor
ofTherefore,
the motor.
In addition,
it is related
to demagnetization
the air-gap
as well.
an analysis
of the characteristics
of the magnetic
circuit is necessary.
2
phenomenon that affects the motor characteristics 5. Figure 3 shows a basic model and Table 1 shows the specifications.
Figure
shows
the
shape variables for the width and rib of the permanent magnet.
Vol
9 (14)4| April
2016
| www.indjst.org
Indian Journal of Science and Technology
3.1 Characteristics of the Magnetic Circuit of the Spoke-type IPMSM
The reason for analyzing the characteristics of the magnetic circuit of the IPMSM with a permanent magnetic is
know the size of the air-gap magnetic flux. The spoke-type IPMSM has used more permanent magnets than a comm
bar-type IPMSM. However, a large magnetic flux can be created in the air-gap despite using less permanent magnet by t
performance of the permanent
magnet Kim,
and reducing
the cross-sectional
area of the
air-gap
canJu
lead
to a large magnetic fl
Yun-Soo
Jun-Young
Kim, Dong-Woo
Kang
and
Lee
in the air-gap as well. Therefore, an analysis of the characteristics of the magnetic circuit is necessary.
ratio and set up the output required for ­loading vehicle
engine cooling fan and the maximum value of output
phase voltage in accordance with an inverter PWM modulation system. In addition, we minimized the stack length
to reduce the inertia for driving the fan and designed in
accordance with rated speed.
2.2 Variables of Rotor Shapes
As shown in Figure 4, we attempted to analyze the impact
Figure 5. The magnetic circuit including a permanent magnet.
on the air-gap flux density through changes in the width
Figure 5. The magnetic circuit including a permanent
of permanent magnets, a design variable of the magmagnet
netic circuit of the spoke-type IPMSM and rib through
which.
Assuming that the magnetic permeability of the core is
very large, Hc1, Hc2, Hc3 are relatively small enough to be negligible and thereby a simple equation (2) can be obtained.
3. Cogging Torque Characteristics
in Accordance with the Air-gap
Flux Density
In this section, we investigated the characteristics of
­cogging torque in accordance with distribution of airgap magnetic flux density. For this purpose, we analyzed
dimensional changes in permanent magnetic which are
the design variables of magnetic circuit from the data of
the same rotors and the effects of the rib structure on the
air-gap magnetic flux density after analyzing the characteristics essential to the design of the spoke-type IPMSM.
Afterwards, we investigate the driving characteristics of
the spoke-type IPMSM using the finite element method.
3.1 Characteristics of the Magnetic Circuit
of the Spoke-type IPMSM
The reason for analyzing the characteristics of the magnetic circuit of the IPMSM with a permanent magnetic is to
know the size of the air-gap magnetic flux. The spoke-type
IPMSM has used more permanent magnets than a common
bar-type IPMSM. However, a large magnetic flux can be
created in the air-gap despite using less permanent magnet
by the performance of the permanent magnet and reducing the cross-sectional area of the air-gap can lead to a large
magnetic flux in the air-gap as well. Therefore, an analysis of
the characteristics of the magnetic circuit is necessary.
Provided that the magnetic flux flows in the magnetic
circuit including the permanent magnetic in Figure 5. an
equation (1) can be obtained from applying Ampere’s law.
∫ H × dl = H mlm + H c1lcl + H c 2 lc 2 + H c 3lc 3 + 2 H g l g = 0 [ A] Vol 9 (14) | April 2016 | www.indjst.org
(1)
H mlm ≈ −2 H g l g [ A] (2)
Moreover, since the total magnetic flux of the air-gap and
total magnetic flux of the permanent magnet are the same if
the leakage is ignored, the relationship between the magnetic
flux density Bg of the air-gap and the magnetic flux Bm inside
the permanent magnet is shown in the equation (3).
Bg =
Sm
Sg
Bm [T ] Sm Bm = S g B g (3)
(4)
Here, Bm, Bg represents the magnetic flux density of
the permanent magnet and air-gap, respectively and Sm, Sg
represents the cross-sectional area of the permanent magnet and air-gap, respectively.
The equation (5) can be obtained by substituting the
equation (3) to the equation (2) and the smaller the air
gap is, the closer value to the residual magnetic flux density of the permanent magnet Bm becomes. In addition,
the intensity of the magnetic field may be referred to as a
critical value since it is directly related to the cross-sectional area and air-gap length of the permanent magnet.
H m ≈ −2
Bm Sm l g
µ 0 S g lm
[A / m]
(5)
3.2 Characteristics in accordance with the
Width of the Permanent Magnet
As shown in the equation (3), increasing the air-gap
magnetic flux as a result of increasing the cross-sectional
area of the permanent magnet is shown in Figure 6.
Indian Journal of Science and Technology
3
As shown in the equation (3), increasing the air-gap magnetic flux as a result of increasing the cross-sectional
the permanent magnet is shown in Figure 6. Accordingly, the phenomenon that the cogging torque was in
appeared and it is necessary to investigate the relationship between the impact on efficiency and torque by an
torque ripple through the load analysis.
Reliability Analysis of Permanent Magnet and Air-gap Flux Density of Spoke-type IPMSM for Driving Cooling Fans
3.3 Characteristics in accordance with the Rib Thickness
Accordingly, the phenomenon that the cogging torque was
increased appeared and it is necessary to investigate the
relationship between the impact on efficiency and torque
by analyzing torque ripple through the load analysis.
3.3 Characteristics in accordance with the
Rib Thickness
H dl H l H l H l
Provided
Provided that
that the
the magnetic
magnetic flux
flux flows
flows in
in the
the magnetic
magnetic circuit
circuit including
including the
the permanent
permanent magnetic
magnetic in
in Figure
Figure 5.
5. an
an
ation
ation (1)
(1) can
can be
be obtained
obtained from
from applying
applying Ampere’s
Ampere’s law.
law.
 H
dl Hmmlmm Hcc11lclcl Hcc22lcc22 H
Hcc33llcc33 22H
Hggllgg 00 [[A
A]]
(1)
(1)
Figure 7 showsof the
characteristics
of the air-gap
flux
Assuming
are relatively small enough to be
(a)
c ,, H
c ,, H
c are relatively small enough to be
Assuming that
that the
the magnetic
magnetic permeability
permeability of the
the core
core is
is very
very large,
large, H
H
H
H
(a)
c
c
c
densityequation
and the cogging
torque in accordance with the rip
igible
igible and
and thereby
thereby aa simple
simple equation (2)
(2) can
can be
be obtained.
obtained.
within the rotor. As the thickness of the rib gotHthinner,
the ]
22H
(2)
Hmmllmm
Hggllgg [[A
A]
(2)
level of the air-gap magnetic flux was increased,
thereby
Moreover,
since
the
total
magnetic
flux
of
the
air-gap
and
total
magnetic
flux
of
the
permanent
magnet
are
the
same
Moreover, since theincreasing
total magneticthe
fluxcogging
of the air-gap
and total
flux of thetorque
permanent
are the same if
if
torque
as magnetic
well. Cogging
is magnet
leakage
of the air-gap and
the magnetic flux m
leakage is
is ignored,
ignored, the
the relationship
relationship between
between the
the magnetic
magnetic flux
flux density
density B
Bm
Bgg of the air-gap and the magnetic flux B
generated
due
toequation
the original
slot and is proportional to
de
(3).
de the
the permanent
permanent magnet
magnet is
is shown
shown in
in the
the equation
(3).
the square of the rotor. Therefore, the characteristicsSSof
m
B
(3)
Bgg Sm B
Bm [[T
T]]
(3)
the cogging torque are changed by the air-gap magnetic
Sgg m
flux rather than the difference in the magnetic resistance.
SSm B
SSg B
(4)
m
g
(4)
m Bm
g Bg
Moreover, as shown in Figure 7(a), the distorted portion
Here,
represents
the
magnetic
flux
density
of
the
permanent
magnet
and
air-gap,
respectively
and
B
,
B
S
,
S
Here, Bmm , Bgg represents
flux
densityinof the
the permanent
magnet
and air-gap,
(b)
withthe
themagnetic
pitted
center
waveform
of the
air-gaprespectively and Smm , Sgg
(b)
esents
the
cross-sectional
area
of
the
permanent
magnet
and
air-gap,
respectively.
esents the cross-sectional area of the permanent magnet and air-gap, respectively.
magnetic
flux
can
be
seen
as
a
unique
feature.
This
can
Figure
7. Result
analysis
of the
characteristics
rotor rip
The
(2) and
smaller
the
air
gap
Figure
7. the
Resultin accordance
analysis with
of thethe
characteristics in
The equation
equation (5)
(5) can
can be
be obtained
obtained by
by substituting
substituting the
the equation
equation (3)
(3) to
to the
the equation
equation
and the
the
smaller flux
the
air
gap is,
is,
the
(a)(2)
Air-gap
magnetic
density
(b)the
Cogging torque.
also
be
seen
as
a
figurative
feature
because
the
magnetic
er
value
to
the
residual
magnetic
flux
density
of
the
permanent
magnet
becomes.
In
addition,
the
intensity
of
B
er value to the residual magnetic flux density of the permanent magnet Bmm becomes. In addition, theaccordance
intensity of thewith the rotor rip (a) Air-gap magnetic flux
netic
to
value
itit is
related
the
area
and
air-gap
flux from
permanent
directly
into7the
netic field
field may
may be
be referred
referred
to as
as athe
a critical
critical
value since
since magnet
is directly
directly
related to
toenters
the cross-sectional
cross-sectional
areathe
and
air-gap length
length
Figure
shows
characteristics
of the air-gap
flux density and the cogging torque in accordance with the rip
density
(b)
Cogging
torque.
he
he permanent
permanent magnet.
magnet.
the
rotor.
As
the
thickness
of the rib got thinner, the level of the air-gap magnetic flux was increased, thereby inc
air-gap in the case of the spoke-type IPMSM. Due to this
the cogging
B torque
S lg as well. Cogging torque is generated due to the original slot and is proportional to the square
feature, the waveform of the air-gap flux density
is difficult
22 Bmm Smm lgthe[[ A
/m
(5)
H
rotor.
characteristics
of the cogging torque are changed by the air-gap magnetic flux rather t
(5)
Hmm Therefore,
m]] Result
Sg lm A/3.4 of the
Parametric
in with the pitted cente
0 the
difference in
resistance. Moreover,
as shown
in Figure 7(a),Analysis
the distorted portion
m
0 Sg lmagnetic
to control directly by the shape or the magnetization
waveform of the air-gap magnetic flux can be seen as a unique feature. This can also be seen as a figurative
accordance with Shapes
direction
of the
permanent
magnet.
3.2
3.2 Characteristics
Characteristics in
in accordance
accordance with
with the
the Width
Width of
of the
the Permanent
Permanent Magnet
Magnet because the magnetic flux from the permanent magnet directly enters into the air-gap in the case of the spoke-type I
1
1
2
2
3
3
Due to this feature, the waveform of the air-gap flux density is difficult to control directly by the shape
magnetization direction of the permanent magnet.
3.4 Result of the Parametric Analysis in accordance with Shapes
(a)
(a)
(a)
(b)
(b)
(b)
(a)
(a)
(a)
(b)
(b)
(b)
Figure 8. Torque and efficiency of the rotor in accordance with shapes
Figure 8. Torque and efficiency of the rotor in accordance with shapes
Figure 6. Result analysis of the characteristics
in permanent
Figure
8. (b)Torque
and efficiency of the rotor in accordance
(a) Width of the
magnet
Rib thickness.
(a) Width of the permanent magnet (b) Rib thickness.
accordance with the width of the permanent magnet (a) Airwith shapes (a) Width of the permanent magnet (b) Rib
3.5 Demagnetization
Interpretation
gap magnetic flux density (b) Cogging torque.
thickness.
3.5 Demagnetization
Interpretation
4
Vol 9 (14) | April 2016 | www.indjst.org
The characteristics of the permanent magnet vary according to temperature, magnetic circuit and external m
The characteristics of the permanent magnet vary according to temperature, magnetic circuit and external m
field. In the case of a non-rare earth metal-based ferrite magnet, a large reverse field at low temperature can
field. In the case of a non-rare earth metal-based ferrite magnet, a large reverse field at low temperature can
irreversible demagnetization. If the reverse field below the knee point takes place in the B-H curve of the per
irreversible demagnetization. If the reverse field below the knee point takes place in the B-H curve of the per
magnet, irreversible demagnetization occurs55. In addition, the properties are changed by heat and the low
Indianthe
Journal
of Science
Technology
magnet, irreversible demagnetization occurs . In addition,
properties
are and
changed
by heat and the low
temperature, the coercive force is. The material of the permanent magnet used in this paper is 7BE and the B-H c
temperature, the coercive force is. The material of the permanent magnet used in this paper is 7BE and the B-H c
shown in Figure 8. As described above, demagnetization of the ferrite magnet can take place if the temperature be
shown in Figure 8. As described above, demagnetization of the ferrite magnet can take place if the temperature b
low. This can be referred to demagnetization at low temperature and the operation point become below the kne
low. This can be referred to demagnetization at low temperature and the operation point become below the kne
due to changes in the residual magnetic flux and the coercive force according to the temperature.
Yun-Soo Kim, Jun-Young Kim, Dong-Woo Kang and Ju Lee
3.5 Demagnetization Interpretation
The characteristics of the permanent magnet vary according
to temperature, magnetic circuit and external magnetic field.
In the case of a non-rare earth metal-based ferrite magnet, a
large reverse field at low temperature can lead to irreversible
demagnetization. If the reverse field below the knee point
takes place in the B-H curve of the permanent magnet,
irreversible demagnetization occurs5. In addition, the
Figure 8. Demagnetization ratio per area in accordance with the width of the permanent m
Figure 8. Demagnetization ratio per area in accordance
properties are changed by heat and the lower the temperature,
ratio magnet.
per area in accordance with the width of the permanent m
with the Figure
width8.ofDemagnetization
the permanent
the coercive force is. The material of the permanent magnet
used in this paper is 7BE and the B-H curve is shown in
Figure 8. As described above, demagnetization of the ferrite
magnet can take place if the temperature becomes low. This
can be referred to demagnetization at low temperature and
the operation point become below the knee point due to
changes in the residual magnetic flux and the coercive force
according to the temperature.
By looking at the demagnetization ratio per unit area
Figure 9. Demagnetization ratio per area in accordance with the rip thickness.
(a)
according to the width of the permanent magnet as shown
Figure 9. Demagnetization ratio per area in accordance with the rip thickness.
in Figure 8, it can be seen that the larger the width of the
looking at the demagnetization
per in
unitaccordance
area according to the width of the
Figure 9. By
Demagnetization
ratio perratio
area
Figure 8, it can be seen that the larger the width of the permanent magnet, the more d
with the reason
rip thickness.
permanent magnet, the more demagnetization is generfor this atphenomenon
is that the
permanent
is closetotothethe
air-gap
d
By looking
the demagnetization
ratio
per unit magnet
area according
width
of the
Furthermore,
thebedemagnetization
ratio the
is increased
to the reverse
magnetic
field db
ated. The reason for this phenomenon is that the permanent
Figure 8, it can
seen that the larger
width of due
the permanent
magnet,
the more
stator.
9 shown
the demagnetization
ratio in accordance
with
the rip
thickness
andd
reason Figure
for this
phenomenon
is that the permanent
magnet is
close
to the
air-gap
magnet is close to the air-gap due to an increase in the
smaller
demagnetization
ratio is. We
analyzed
the thickness
at an
interval
of 0.2mm
4. Conclusion
Furthermore,
the demagnetization
ratio
is increased
due to the
reverse
magnetic
fieldtob
zero
the horizontal
represents the model
which the rib
is not
present.
The and
mai
stator.inFigure
9 shown axis
the demagnetization
ratio in
in accordance
with
the rip
thickness
width. Furthermore, the demagnetization ratio is increased
the
rib has
the largest demagnetization
is that the
of the
stator doe
smaller
demagnetization
ratio is. We analyzed
themagnetomotive
thickness at anforce
interval
of 0.2mm
to
This
paper
concerns
a
concentrated
flux
structure
the
magnet.axis
On represents
the other hand,
in theinmodel
which
thenot
ribpresent.
is present,
due to the reverse magnetic field by the magnetomotive
zeropermanent
in the horizontal
the model
whichinthe
rib is
Thethe
maim
leaks
into
and affects
the permanent
magnet
less.
the rib
hasthe
therib
largest
demagnetization
that
the magnetomotive
force of the stator doe
­spoke-type
IPMSM
and
analyzes
the ischaracteristics
of the
force of a stator. Figure 9 shown the demagnetization ratio
the permanent magnet. On the other hand, in the model in which the rib is present, the m
motor byleaks
analyzing
air-gap
magnetic
fluxless.
density and
4. into
Conclusion
the ribthe
and affects
the permanent
magnet
in accordance with the rip thickness and the larger the rib
This paper
concerns a the
concentrated
flux
structure the
spoke-type
IPMSM and analyzes t
cogging
torque.
To
analyze
factors
affecting
air-gap
thickness is, the smaller demagnetization ratio is. We(b)
ana4. Conclusion
analyzing
the air-gap magnetic flux density and cogging torque. To analyze the factors af
magneticweflux,
we focused
changes
in the
shapes
focused
changesaon
in
the
rotor shapes
and rotor
carried
out analysis
cogging
lyzed the thickness at an interval of 0.2mm to 0.58mm and
This
paperonconcerns
concentrated
flux structure
spoke-type
IPMSM of
andthe
analyzes
t
demagnetization
through
changes
in
the cross-sectional
areas
andTorib
thickness.
Especial
Figure 8. Torque and efficiency of the rotor in accordance with shapes and carried
analyzing
the
air-gap
magnetic
flux
density
and
cogging
torque.
analyze
the
factors
af
out
analysis
of
the
cogging
torque,
torque,
the part(a)marked
by
zero
in
the
horizontal
axis
represents
the
thickness
of
the
output
by
the
cross-sectional
area
of
the
permanent
magnet.
Since
a
Width of the permanent magnet (b) Rib thickness.
we focused on changes in the rotor shapes and carried out analysis of the cogging
IPMSM
canthrough
use non-rare
permanent
magnets
which
are more
adv
efficiencytype
and
demagnetization
through
changes
inandthe
demagnetization
changes earth-based
in
the cross-sectional
areas
rib
thickness.
Especial
the model in which the rib is not present. The main reason
permanent
magnets
in terms
oftheprice,
it is suitable
electronics
the thickness
of theand
output
cross-sectional
areaforof automotive
the large
permanent
magnet. areas
Sincewa
cross-sectional
areas
ribby
thickness.
Especially,
important.
However,
spoke-type
IPMSM
has disadvantages
in terms
of cog
3.5 Demagnetization
why this model
without theInterpretation
rib has the largest demagnetype IPMSM
can use the
non-rare
earth-based
permanent
magnets which
are more
adv
demagnetization.
Therefore,
this
paper,
propose
aoutput
solution
toby
thiselectronics
problem. areas w
permanent
magnets
in terms
ofthickness
price,
it we
is suitable
automotive
proportion
in circuit
width
than
theinmagnetic
of
thefor
of the permanent
according
magnetic
and
external
tization is The
thatcharacteristics
the magnetomotive
forcemagnet
of thevary
stator
doesto temperature,
important.
the can
spoke-type
has disadvantages in terms of cog
field. In the case of a non-rare earth metal-based ferrite magnet, a large
field
at lowHowever,
temperature
lead to IPMSMmagnet.
thereverse
cross-sectional
area
of ​​the
permanent
Since
Therefore,
this
paper, we propose a solution
to this problem.
not leakirreversible
into the demagnetization.
rib and affectsIfthe
On point takes
thepermanent
reverse field magnet.
below the knee
placedemagnetization.
in5.theAcknowledgement
B-H curve
of the in
permanent
5
as
a
concentrated
flux,
the
spoke-type
IPMSM
can
use
This
work
was
supported
by
the
National
Research
Foundation
of Korea (NRF) grant
magnet,
irreversible
demagnetization
occurs
.
In
addition,
the
properties
are
changed
by
heat
and
the
lower
the
the other hand, in the model in which the rib is present,
(MSIP)
(No.2015R1C1A1A01055013).
5. Acknowledgement
temperature, the coercive force is. The material of the permanent magnetnon-rare
used in this
paper
is 7BE and
the B-H curve
is
earth-based
permanent
magnets
which
are
more
the magnetomotive
force
of the above,
statordemagnetization
leaks into the
ribferrite magnet can takeThis
shown in Figure 8.
As described
of the
placework
if the
becomes
wastemperature
supported by
the National Research
Foundation
of Korea
grant
Comment
[R3]: AU:
Kindly(NRF)
check the
fig
than
rare
earth-based
permanent
magnets in
numbers
6. References
(No.2015R1C1A1A01055013).
low.
This
can
be
referred
to
demagnetization
at
low
temperature
and theadvantageous
operation(MSIP)
point
become
below
the knee point
and affects the permanent magnet less.
due to changes in the residual magnetic flux and the coercive force according
to the
terms
oftemperature.
price, it is suitable for automotive electronics areas
1. 6.KimReferences
HW, Kim KT, Jo YS, Hur J. optimization methods of torque density for developing the neodymi
Transactions.
May;
49(5):2173–6.
which regard
weight2013
and
price
as important. However, the
1.
Kim
HW,
Kim
KT,
Jo
YS,
Hur J. optimization
torque
density for developing the neodym
spoke-type IPMSM
has
disadvantages
inmethods
termsof of
cogging
Transactions. 2013 May; 49(5):2173–6.
torque, flux leakage and demagnetization. Therefore, in
this paper, we propose a solution to this problem.
5. Acknowledgement
Figure 7. B-H curve.
Vol 9 (14) | April 2016 | www.indjst.org
Figure 7. B-H curve.
This work was supported by the National Research
Foundation of Korea (NRF) grant funded by the Korea
Comment [R4]: AU: Kindly check the fig
government (MSIP) (No.2015R1C1A1A01055013).
numbers
Indian Journal of Science and Technology
5
Reliability Analysis of Permanent Magnet and Air-gap Flux Density of Spoke-type IPMSM for Driving Cooling Fans
6. References
1. Kim HW, Kim KT, Jo YS, Hur J. optimization methods
of torque density for developing the neodymium free
spoke-type BLDC Motor. IEEE Transactions. 2013 May;
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2. Chiba K, Takemoto M, Ogasawara S, Yim WG.
­Ferrite-magnet spoke-type IPMSM with W-shaped magnet
placement. Proceedings IECON; 2013 Nov. p. 2869–74.
3. Ohira S, Hasegawa N, Miki I, Matsuhashi D, Okitsu T.
Torque characteristics of IPMSM with spoke and axial type
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4. Hwang KY, Rhee SB, Lee JS, Kwon BI. Shape optimization
of rotor pole in spoke type permanent magnet motor for
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Proceeding of International Conference on Electrical
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5. Hong CH, Seol HS, Jun HW, Liu HC, Lee J. Characteristic
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Oct 22–25. p .421–4.
6. Ionel DM, Balchin MJ, Eastham JF, Demeter E. Finite element analysis of brushless DC motors for flux weakening
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Indian Journal of Science and Technology