W
Prtvitc Wvftllj Pete
international Review ofl-Ilectiuicwtl Engineering (l. R. E. E. j, l'ol. 5, tN". 2
ri-larch-elpril 20H}
Performance Analysis of a Capacitance Compensated Dual Stator
Winding Synchronous Reluctance Machine
A. s. 0. Ogunjuyigbc. A. A. Jimoh 2, o. v. Nicolae i. E. s. Obe 3
Abstract Synchronous relucrtanc-e tnac-hine with simple salient rotor are known to have poor
power factor because they have a low effective reactant-e ratitt. This paper used a J-pltase
attxiliary winding and balanced capacitance compensation to injlttence the eective reactant-e
ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power
factor and torquetampere pierformance is improved A mathematical mtxlel and dq equivalent
circuit suitable for dynamic and steady state analysis was developed and used to stuttfv the
synchronous operation of this machine. rlnalytical as well as experimental results-for a 4-pole. 36
slots simple salient rotor teluc-tancc machine showed that the ective rettctance ratio increased
with the capacitance size, and the machine operated at a maximum powerfactor of ft. 969 ivitl-tottt
altering the geometry of the rotor. The torque per ampere of the machine also improved with the
size of capacitor attached to the atailiary winding. Copyright © Zttltl Praise Worthy Prize S. r.l.
- All rights reserved.
Keywords: Balanced Auxiliary Winding. Capacitor (cmpensation. Dttal Winding. bynchronotts
Reluctance Machine. AC A/lachines
A considerable amount of research efforts devoted to
synchronous reluctance machine in the past ten decades
has demonstrated the machine to be an attractive
alternative to other AC machines (permanent magnet,
Induction and Switched reluctance machines) in high
performance, variable speed applications. This is as a
result of its ability to withstand harsh environment, its
low inertia, case of construction. high power to weight
ratio and good acceleration performance [ll-[]. Most
often, these research efforts made signicant attempts to
control the rcluctanccs in the cl - and q-axis of the
machine. The efforts have commonly followed the
geometrical trend that has led to the emergence of the
following types of rotor: (i) Simple salient pole type, (ii)
Segmented rotor type, (iii) Flux barrier type, (iv)
Transversely laminated type and (v) Axially laminated
type. 'l'he different rotor congurations have gone
through different design analysis and techniques to
obtain a better performance. Popular amongst these
techniques, as a result of the availability of more
computational power, is the nite element method. Some
of the successes on the rotor congurations are wcll
reported in [2], [3], [71-[1 l]. The geometric approach via
rotor designs has improved the performance
characteristics of reluctance machines. However. the
quest is for improved performance based on a widely
acceptable low cost practicable means. Some research
worlt exploited the benets of multiphase machine
arrangements to dcvclopa high torque performance
Introduction
tltlanuscrrpt received and revised lltarcli Jttl it. accepted April Btlltt
43?
using S-phase, nine phase arrangements rather than the
traditional three phase [|2]-[l5]. In their con-esponding
works, they made use of higher order odd harmonic
component of the current to achieve a better torque
performance. These works reported the following
achievements:
A llP/o torque improvement for the synchronous
reluctance with a simple salient rotor[l6].
Conversely, [l 3] reported only 4% improvement,
A 24% torque improvement for the synchronous
reluctance machine with a simple salient rotor and a
5% torque reduction with the axially laminated rotor
[l5], and
A 4% torque reduction for the ux barrier rotor [ l3].
Most of the works in this direction did not express
how their arrangements inuenced the effective
reactance ratio as well as the power factor of the
machine, [l2]-[l4]. However. reference [l5], concluded
to a fact that the power factor of the synchronous
reluctance machine heavily depend on the rotor structure.
This paper therefore present an effort which is not
based on altering the geometrical structure of a simple
salient rotor and yet changes the effective saliency ratio
of the machine as reected in the air gap eld
distribution for improved power factor and torque per
ampere. The conguration, whose operation and
feasibility are elaborated in this paper, has the machine
furnished with two thrcc phase stator windings identied
as abc and 'xyz. Unlike the doubly fed reluctance
machine. these two windings, abc and xyz. have the
same number of poles. The two windings occupy the
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A. S. O. Ogunjrryigbe, A. A. Jimoh, D. P. Nicolae, E. S. Obe
same stator slots; they are electrically isolated but
magnetically coupled. The rst winding abc is
connected to the utility supply thus carrying the load
current, while the second winding xyz is connected to a
balanced set of capacitance to uniquely inuence the
effective reactance ratio of the machine such that its
power factor performance is likewise enhanced. The
arrangement is used in this work with a simple salient
rotor design for the laboratory experimentation.
An electromagnetic eld concept along with a coupled
circuit approach based on an approximate equivalent
circuit was used to examine the flux distribution of the
conguration in [l7]. On the other hand, this paper
developed mathematical models and dq equivalent
circuit, useful for dynamic. steady state calculations and
computer simulations of the machine. These models were
utilized to investigate the inuence of the capacitance
injected through the auxiliary winding on the effective
axis reactance and power factor performance
characteristics of the proposed synchronous reluctance
machine with simple salient rotor. Calculations,
experimental as well as computer simulation results
conrm the usefulness of the models and the benets of
the conguration.
With the known advantages presented by synchronous
reluctance machine, the conguration discussed in this
paper is expected to extend its application area. It is also
expected to create a renewed attraction to the cheap, and
simple to construct salient rotor for application in the
petrochemical industry where arcing within the machine
is not allowed.
The remainder of this paper is organized as follows:
Section ll describes the general system equations and
mathematical model for synchronous reluctance machine
structure with an auxiliary winding attached to a
balanced capacitor. The expressions for the various
winding inductances are derived, and the dq equivalent
circuits suitable for dynamic and steady state analysis of
the machine were also developed in this section. Steady
state performances of the machine based on the
mathematical model and laboratory experiments,
outlining the benets of the conguration are set up in
section lll, while the results of transient perfonnances
are discussed in section IV. The paper is concluded in
section V.
ll. Machine Model
The conceptual diagram of the proposed machine
structure discussed in this paper showing the simple
salient rotor shape and the auxiliary winding connected
to a balanced capacitor is illustrated in Fig. 1(a). The
clock diagram of the two stator windings in the 36 stator
slots, 4-pole. 3-phase machine is illustrated in Fig. 1th}.
The experimental machine is wound with a full pitch;
single layer winding with the number of slot per pole per
phase as 3. The rst layer is occupied by the main
winding abc and the second layer is occupied by the
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43B
auxiliary winding xyz. The two windings are wound
with the same number of poles and have equal number of
turns. The rotor of the experimental machine used for the
work reported here is of the simple salient type with the
dimensions as listed in Table Ill of the appendix.
e
Milt llllik'
tln
Figs. I. Synchronous reluctance machine with dual stator winding and
capacitance compensation [a] Conceptual diagram of the rotor and
stator {b} Clock diagram ofthe dual stator windings
General and classical assumptions are taking in the
analysis that follows. lt is assumed that the stator
windings are sinusoidally distributed, and the iron of the
stator and rotor are innitely permeable. thus saturation
is not considered.
The voltage equation which describes the electrical
behavior ofthe machine in matrix form can be written as:
_ din L.
rah:- : Rsllrabr: + d: i
it)" .
0 = Rrxy: + " * + he): (2)
where:
lube I Lahrlu-t" + Labia): Irv:
Am = 1., rm + a920,. 1M. (4)
gives the ux linkages ofthe windings.
ti, and L, represent the self and mutual inductances
of each winding, while Laban, and Lxyzx represent the
mutuat as well as the coupling inductances between the
two windings.
lmernanfonul Review ofE-ecrrrcol Engineering. l-"bl. 5. N. 2
A. S. O. Ogtmjinligbe. A. A. Jimoh, D. l1. Nicolas. E. S. Obe
i=;,,,_. = p; i, i-;.]" is)
i, =[i,, i, 1,1 is}
it, =[,i,, .1, 4,1 (t)
t, i.,,,, t,
Loin. = Lin: LN) Lbs"
Lao Lcib Lac
Ln. LI)" LIZ
h: = L}, 1.1,. L}: (9)
L11: Lev z:
Lox Lop" La:
Lubes}: = List-n: z Lin: Liiv Lin:
L L L ..
In equations (1)49), RS1, R3 are diagonal matrices
which represent the stator main and auxiliary winding
resistances respectively. The stator main and auxiliary
winding currents are 1,1,, and i, respectively.
To further illustrate the operation of the machine, the
computation of the machine inductances is important.
NJ.
A convenient approach of determining the inductance
is the winding functions method [l8]-[2l] in which
inductance of the machine are calculated by an integral
expression representing the placement of the winding
turns along the airgap periphery.
in winding functions theory, the self and mutual
inductances between windings i ' and j in any electric
machine can be calculated by:
Stator lndttctances
2x
t. -_- pa»: Ig-l{6.6,,,,]N,(9.8,,,,]N;(6.6m)d9 m)
t)
The effective airgap radius of the machine is given as
r, i is the effective motor stack length. and the
approximated inverse airgap length is represented
by g" [6l.9,.,,,). The angle 6 denes a position along the
stator inner surface while 6,," is the angular position of
the rotor with respect to the stator reference. N, and N,-
respectively indicate the winding functions of the
windings i and j. lt corresponds to the mmf distribution
along the airgap for unit current in winding i andj.
Copyright ti? Ztilil? Praise War-airy Prize S. rJ. - Al! rights reserved
439
The winding functions for the main stator winding
al-Jc is shown in Fig. 2, where C, is the number of coil
per slot for the main winding. This winding function is
similar for the auxiliary winding since they are wound in
the same pattern and for the same number of poles. The
winding function plot of Fig. 2 is seen to be a stepped-
like function due to the discrete nature of the winding
slots, thusa signicant space harmonic components is
present.
+ -B i-A d. +8 -A
OIIOOOIIOOIO
35C" T
B
Jflcn
t u l
33¢
sac, _r "L_ "
ll l
y: c.
__r' i
411C ~
Li I
Figs. 2. Winding functions of |l1e main winding {a} Phase 'a, {b} Phase
b. [c] Phase c
However, to present an understanding of how the
machine operates and to obtain closed form inductance
equations, the stator winding function will be represented
in this analysis by their fundamental component. The
fundamental component has the greatest effect on the
energy conversion and will be sufficient to explain the
fundamental operation of the machine. Thus, the winding
functions of the stator windings are expressed as:
No (i9) = Na ¢°~'*'(P9)
iv',,(9)= i\»'_.,¢as(p0-1-;) (12)
Ne = Nlxl Co-(pg-i 1T1)
Np (9) = Nu 003L067)
N}. (9) = M; cosLpB-z?) (13)
iv, (9) = rig, cosi p9+23l)
where N and N, are the numbers of the fundamental
component turns for the main and the auxiliary winding
respectively.
The inverse airgap function of this kind of machine
can be approximated by the expression [l9], [22]:
iniemaiionnf Review ofEiectrir-ai Engineering. Vol. S. N. .2
A. S. O. Ogtmjiiyigbe, A. A. Jimoh, D. l/f Nicoiae. S. Obe
g4 6.6,_,,,]=m+ncos2p(l5'6,) (l4) did;
A. S. O. Ogtmjwigbe. A. A. Jimoli. D. lK Nicoloe, E. S. Obe
Since the machine is assumed to be magnetically
linear, the co-energy is equal to the stored magnetic
energy and it is expressed as lll,, l._,__.l__.. Hence,
the electromagnetic torque is expressed as:
p i air.
Th" I E ohcxy: 5a iihcrjr:
where:
l. _. t, m
L z til: lx._ )
Lift-rain- {r}:
From (30) and (3l), the electromagnetic torque of a
synchronous reluctance machine with dual stator
winding and capacitance compensation can be written as
a separate sum of the torque produced by each set of the
stator currents to obtain:
3L . -- 5L - .
iia-liaai-Hiiis-i n:
T i E 66, 66, (32)
m 2 ,. 6L: , lstimh
+[.\'_'l': T. fr}: n: aer lube
Substituting the respective inductance matrix
components of equations (8)-(lt]), and simplifying, the
electromagnetic torque (expressed in terms of current) is
obtained as:
_ 5E (Lt-fl iapifailin +(Ltif2 Lqziiiizfqz +
"" 2 2 +[i. l )[i,,i_,, +i,,,i,_,,]
mi rm;
(33)
This equation show that the total electromagnetic
torque developed by the machine is as a result of three
main torque components. This noticeably demonstrates
the inuence of the additional winding introduced in the
machine, as well as the capacitor attached to it. The rst
and the second components are familiar equations which
represent the reluctance torque developed by the main
and the auxiliary winding respectively, while the third
component is the torque developed as a result of the
interaction between the main and the auxiliary winding
currents. If the capacitor is not attached to the auxiliary
winding, (33) will resolve to the familiar electromagnetic
torque equation of a conventional synchronous
reluctance machine. The size of capacitor connected to
the auxiliary winding determines the torque contribution
of the auxiliary winding and that of the interaction
between the two winding currents.
Ill. Steady state Analysis and
Experimental Results
Under steady state operation, with sinusoidal
excitations, the derivatives of equations (23)-(26) are
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441
zero and the general dynamic model given by equations
(23)-(26) is transformed into the following steady state
model:
Vql = Riifqi +X.ii*'ii| +Xiitifa2
Vi = Rnfiii X i
ll ql
0 z Rxzlsd + I¥d2!!2 +.¥m,dfd| +Vt3q
Xmq l; (34)
0 = Raid; - xgiq, - x, 1,, + is,
These resulting equations are then used to determine
the steady state performance characteristic of the
machine.
lll. l. Constant Speed (Jperaiion
When the axis currents are determined from (34) and
back substituted, the steady state axis impedance of the
machine is derived as:
V V qid
- _ L z e
Zqrtl _ Iqd j V C086
Z2 Zn
where:
Z1 = ii n:
Xiiz ' it
z r Y3
- . +
Z ql Yqz _
11', =mLd|,Xu| =wl.q|.l,- =;l(;, and i) is the rotor
angle. J=0, when the machine axis coincides with the
axis of stator phase and all when it coincides with the
quadrature axis. The effect of the capacitance attached to
the auxiliary winding on the effective d-and q-axis
reactance is calculated using equation (35) and compared
with the experimentally obtained values in the plots of
Fig. 4. The measured values of the direct axis reactance
(Xd) were obtained at i500 rpm and the quadrature axis
reactance (Xq) were obtained at pull-out point using the
Honsinger method [24], [25].
Y t t | i _i
---c.|mam1 1:. '
--t'-|rnw-c s, _
25° ----- arm-mi x
Ill-i Measured K I
_ ~ . . i
i i
Kr |5|-|_ . . . . . _ . .. _
at §
tan-- ------- ------------ -- --; _ _ _ _-,..-m=!
i 1555"-
so nu I-I '.I.''.i...'.-_'f.-IT_
.. t I t
1 1-5 \ 3.5 l 1.! 5 5.! 0
Capacitance (F) m
Fig. 4. Variation of the effective axis reactance as a function of
capacitance
lniemiiiioiiol Review ifElecuical Engineering. Vol. 5. N. .2
A. S. 0. Ogunjtqiigbe, A. A. Jimoh. D. if Nicolae. E. S. Obe
The effective d-axis reactance of the machine was
found to obviously increase with the size of the
capacitor, while the q- axis reactance was only slightly
inuenced. This situation on its own indicates that the
conguration increased the effective reactance ratio of
the machine. To illustrate the effect of the conguration
on the power factor of the machine, the input active and
reactive power of the machine is calculated using:
3 . .
i; = E(Pq|fq} + I-dlldi) (36)
3 _. .
Q=giiqiiut _}Ji1ql) (37)
Using (36) and (37), the variation of the power factor
of the synchronous reluctance machine with the
conguration as a function of the size of the capacitor
and load angle is evaluated using:
a us)
Pf+Q
603$ =
and the peak current in each phase calculated using:
[s] : VIIjI + rtfl
where:
l X Y
jd|= (40)
xrdl('¥tflrt')_'xlmif
J ix: _ Y) <41)
are the axis cun-ents of the main winding and are derived
from (33), i}, =Vsin5; Vql = Vcos .
Plots illustrating the variation of the reactive power
as a function of the capacitance (attached to the auxiliary
winding) are generated using (37)-40 and displayed in
Fig 5. For every load angle examined. the main winding
reactive power reduces with an increase in the size of the
capacitance attached to the auxiliary winding, and in
some cases getting to zero. This invariably reduces the
input apparent power of the machine and it indicates that
the machine can be operated at very high power factor
and unity power factor in some cases. While the best
power factor obtainable with no capacitor attached to the
auxiliary winding is about 0.55, a power factor as high as
0.99 was predicted for the machine with capacitance
fitted to the auxiliary winding.
Fig. 6a displays the calculated power factor against
the size of the capacitor. The general trend in these plots
of Fig. 6(a) is the same for all load angle. and illustrates
that the inherent power factor of the machine increase
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with the increase in the size of capacitor. However, the
size of the capacitor that can be attached to the auxiliary
winding is well constrained by its ampere turn rating
The main winding current is shown in Fig. 6(b) to
increase with an increase in the load angle and for every
load angle considered the points of minimum main
winding currents consistently match the points where the
highest power factor are obtainable. The possibility of
using the capacitance attached to the auxiliary winding to
inuence the power factor to either high. leading or
lagging values is also evident in Fig. 6th).
Load angle
-_.,_ go
Main inbuilt:
rnoetre power-trams IIHJI
1
It It.) HA 8.! 0.8 l
Capacitance (F) , m"
Fig. 5. Variation of the input reactive power as a function of
capacitance
Load nil!
5' . .
0.0 its --------- --------- --
i is Q
:01
...--. :5:
l
I'm-rec factor
Q
5
OJ
0.1 I
D 0.2 0.4 0.6 0.8 1
Capacitance ( F] m
la]
Lind upln
---.__gu
-.,- m.
i u.
~--- zo-
-- ¢III.III l!»
i;
Main winding curl-ml IA}
41.5 c 0.: 1 1.:
Power [actor angkr (rad)
(b)
Figs. b. (a) Variation of the power factor as a function of capacitance,
(h) Variation of the main winding current as a lilnction of
power factor angle
:3:-
m
lnrenmtionuf Review of Electrical Engineering. Vol. 5. N. 2
.»-I. S. O. Ogttrgittytgbe. A. A. Jimoh, D. if Nicotoe. E. S. Obe-
HtYZ. flxperimetrtcrl Results
The synchronous reluctance machine with dual
winding and capacitance compensation was adapted and
fabricated from a three phase 36 stator slots induction
motor with a frame size DZIIZM. The conventional
stator of the machine was rewound following the
practical arrangement of the stator windings shown in
Fig. lib). The main winding of the machine is supplied
directly from the mains utility supply. However. since
the experimental machine is not equipped with a damper
winding, it cannot start on its own even with this
configuration. The machine was synchronized in the
laboratory using a DC machine operated in the motoring
regime. A labeled pictorial representation of the
experimental set up is shown in Fig. 7.
Measured power factor, current and torque with
different capacitor sizes (l5 pF. 45 uF, 60 uF. 75 pF,)
attached to the auxiliary winding are respectively
displayed in Tables l and ll. While the machine is able
to deliver its rated load, table I clearly showed that the
machine operates at a comparatively higher power factor.
Similarly, Table ll show that for every load point
considered, the torque per ampere of the machine
increased with the size of the capacitor, thereby
justifying the fact that the conguration discussed in this
paper improved the torque per ampere without varying
the rotor geometry of the machine. The effective axis
reactances of the machine were measured using the
Honsinger methods [25]. and the results were closely
compared to the ones analytically calculated in Fig. 4.
The no-load current of the machine as recorded in table
Il is found to drop with the increase in the size of the
capacitor; consequently. the effective direct axis
reactance of the machine also increased with the size of
the capacitor. On the other hand. the quadracture axis
reactance is only slightly inuenced by the
conguration, therefore, the effective reactance ratio of
the machine as viewed from the source increased with
the size of the capacitor. Consequently. the power factor
and torque per ampere performance characteristics ofthe
machine is improved.
Dill: acquisition w ca? (or
equipments hank
DC Experimental
machine
Machine
Fig. l. Pictorial view ofthe experimental setup
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TABLE l
MEASURED Power: FACIOR PERFORMANHECliAR.~\C']'[ER1S'l'|{" AT
Vnxtous Loan, AND C APALTFITJR SIZE
Load Power Power Power Power
[pul factor with factor with factor with factor with
T5 pF 60pF 45 uF l5 pF
capacitor capacitor capatcittir capacitor
0.0 0.932 0. 8'07 £1.68 0.41
0.1 0.95? 0.84 0.739 0.494
0.2 0.963 0.902 0.li|5 0.604
0 3 0 96? 0.909 0.84 0.6?
0.4 0.969 0.92 086 0306
0.5 0.969 0.924 0.862 0.725
0.? 0.967 0.91 0.86 0 T39
0.8 0.963 0.9|5 (1.85 0J4
0.3 £1.95? (1.905 0.85 0.72
0.9 0.949 0 906 0.83 0.68
I 0 0.939 0.906 0.8 0.62
TABLE ll
MEASURED MAIN WINIIIING CURRENT AT VARIOUS LOAD AND
CAPACITOR SIZES
Load Main Main Main Main
(pu) winding winding winding winding
Current with Current Current with Current with
T5 pl with 60pF 45 uF l5 pF
capacitor capacitor capacitor capacitor
0.0 2.00 1.99 2.28 3i
0| 2.33 2.33 2.34 3 3
0.2 2.9? 2 {l4 3.00 3.?
0.3 3.4? 3.29 3.30 4 I
0.4 3 S6 3.68 3.80 4.5
0.5 4.20 4.02 4.50 4 S
0.? 4.54 4 34 5.00 5.2
0.8 4.92 4 33 5.40 5TH
0.8 5 39 5.29 6.20 6J6
0.9 5.99 6. I9 6.90 6.04
1.0 6T8 T.6l 7.13
The nature of the current and voltage waveforms in
the main and auxiliary winding of the motor with 8 Nm
load applied to the motor is shown for different sizes of
capacitor in Fig. 8{a)-(d). The presence of harmonic in
the phase current is obvious; and the measured THD
showed that the harmonics of the machine with
compensation is better than the conventional machine,
particularly and improved with the size of the load as
well as the size of capacitor. A typical distribution of the
THD measured for a 60 pF capacitance and with a load
of 8 Nm is displayed in Fig. 9. As expected from the
winding conguration used for the experimental
machine, apart from the fundamental the phase belt
harmonics are the most prominent.
The experimental trace of Fig. Std) displays that a
leading current flows in the auxiiiary winding. This
leading current inuences and directly shift the main
winding current along the axis as the size ofthe capacitor
is increased. The shift in the phase ofthe current (evident
in Fig. 9(a)-(c) is such that the power factor is inuenced
from lagging towards a leading power factor.
fntertruttotttti Review 0fEfet.tt'frttt' Engtncewttrg. i191. 5. N. Z
A. S. U. Ogtmjuyigbe. A. A. Jimoh. D. P. Nicoloe, E. S. Obe
W l" T hhinwiarlingclrrus -
m m, JFK _' . . ._.
_ lllll -\
w .. / J i/
h
t! run {I I
m m n ___ Main-dug ' voltage
m LEM 1-0- v -
(i!)
$ MHI
.-|..-,[.....-.
s m: Slab winding current
II Jon
III lllll
QU ill
IIE Gk
J5 Si:
' uihwiiliiiiYell-II!
~$ tilt!
HIII IQOn
(b)
V-lw
,,, c.
m U Mam I'm ' gclrnll i
IQ .[l.'- K I
IE ltl- I
.. .4 I
in m. _. .. kl .. .
IB a-I i- - ma
" " _ _ Mlinwilldingvoltage
II qt. ..., I||- .....| .i..-... I
I'm-g Jimiu
(C)
..
1-1:.»
(d)
Figs. 8. Steady state waveforms of the motor on S Nm load; Red; peak
value ofthe main winding current ( ltlaidiv}; Black: peak value ofthe
main winding voltage [I00 Vidiv). Machine tted with (a) l5 pF [b] 45
pF_ (c) 60 |.iF capacitor, and (d) Auxiliary winding voltage and current
with 6i] pF capacitor
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I -
a a t r e
Hum-enume-
Figs. 9. (a) Total Harmonic distortion ofthe main winding current with
the application of8 Nm load and 60 pF capacitor
IV. Conclusion
The use of auxiliary winding and capacitance
compensation to improve the effective reactance ratio of
a synchronous reluctance machine with simple salient
rotor is presented and discussed in this paper. By the
application of winding functions and the transformation
theory, a mathematical model and equivalent circuit
suitable for dynamic, transient and steady state analysis
was developed for a synchronous reluctance machine
with an auxiliary winding for capacitance compensation.
The developed model was used to conduct an
investigation of the effect of the conguration on the
etTective reactance ratio, power factor and torque per
ampere of a simple salient rotor synchronous reluctance
machine.
Validating experimental results of the analytical
developments are provided showing perfonnancc
characteristics of a 4~p0le 36 slots experimental machine
adapted -om an induction motor. The experiments as
well as the analytical study clearly showed that the
effective reactance ratio of a synchronous reluctance
machine is improved without altering the geometry of the
rotor as it is conventionally done. With this improvement
of the effective reactance ratio, synchronous reluctance
machine with a simple salient rotor was operated at a
better power factor and torque per ampere for all
operational loads. A maximum power factor of 0.969 as
against the 0.55 for the uncompensated was obtained.
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Copyright © 20 l 0 Praise Horthy' Prize S. r. l. - All riglus reserved
445
Appendix
TABLE A I
PARAMETERS OF THE EXPERIMENTAL MACHINE
Voltage _.I" I50 V
Frequency] 50H:
Rated main winding current. 8.8 A
Number of poles. P 4
Unsaturated direct axis reactance . .'t'.i 43.3] t1
Unsaturated quadracttire reactance . X, I260 t1
Air-gap at the pole Face. g| 0.25 mm
Aiigap between pole. g; I2 mm
Stack length ]48.5mm
Number of stator slots 36
Main winding resistance. R,,| 414i)
Auxiliary winding. Rn 14.90
Pole arcipole pitch ratio =05
Authors information
'ElectricaliE-Ilectionic Engineering department. University of lbadan .
lbdw- Nissan
Electrical Engineering department. Tswane University of Technology,
Pretoria.
Emails: iimhméiltui-aiam;
Electrical Enginering Department. University ofNigcria ,Nsultka..
Nigeria. oggnngh ahoocom
Ogunjuyighe Ayodeji Samson received B.Eng
degree in I99] from the Bendel state University,
an M.Sc with distinction in I995 from the
University of Lagos. Lagos. Nigeria. and a
D.Tech from the Tshwane University of
Technology. Pretoria. South Africa.
Since I998, Ayodeji has lectured in the
ElectricallElectronic Engineering department of
the University of Ibadtin. Nigeria. He is a corporate member of the
Nigeria Society of engineer His research interests are in the eld of
performance improvement oi Electric Machines. and contingency
planning in power systems.
Adina A. Jimoh (MIEEE I986} received Sling
degree in I97? and M.Eng. degree in I980. both
from Ahmadu Hello University (ABU) Zaria.
Nigeria and Ph.D. degree Iiom McMastei
University. Hamilton, Canada in I936. He was
with Ahmadu Bello University up till I992,
when he moved to the Research & Development
unit of the National Electric Power Authority
(NEPAJ Nigeria. Adisa was with NEPA up till I996 when he relocated
to University oi Durban-Westville. Durban, South Africa where he
taught courses and carried out research in high performance energy
efficient electric machines and power systems. and power electronics.
In 200] he joined Tshwane University of Technology. Pretoria. where,
as a full professor, he leads and coordinate the research and doctorate
programs of the Graduate School of Electrical and Electronic
Engineering. He is a registered engineer in South Africa. His research
interests are in the eld of Electric Machines. Drives and Power
Electronics application in Power Systems.
Dan Valenlin Nicola: [MIEEEJ was born in
I943. in Bticharest. Romania. lie graduated the
Polytechnic University of Bucharest. Romania in
.|iily I97] with Msc degree and got his doctorate
degree in 2004 at Vaal University of
Technology, South Aica.
Aer graduation he worked as researcher in the
Institute for Nuclear Technologies. National
c
litter-national Review ofi-Ilectrical Engineering. Ibl. .5. N. 2