838

Abstract This paper describes the design and fabrication

of single phase capacitor run induction motor in an optimized
manner using Perturb and Observe (P&O technique) to
enhance the efficiency of existing design. Output power of the
induction motor is directly proportional to the active volume of
the material ie, D
2
L of the motor. Where D is the diameter and
L is the length of the motor. The value of D
2
L can be calculated
for the different values of D and L. But P&O technique helps
us to select the optimal value of D and L combination in order
to achieve the maximum efficiency. A generalized algorithm is
developed for the design of stator core stamping, rotor core
stamping, main winding, die-cast rotor, auxiliary winding and
capacitor value in an optimized manner using P&O Technique.
Based on that, dedicated software is developed in MATLAB
and various design parameters are obtained for 75W, 220V,
50Hz, 4 pole capacitor run induction motor. In order to verify
the designed parameters a steady state mathematical model of
the motor is developed using double field revolving theory and
it is simulated in MATLAB/SIMULINK platform. Based on
the obtained optimal designed parameters, different parts of
the motor are fabricated and the fabricated motor is tested
successfully in the electrical laboratory. Output performances
of both simulation and experimentation are also investigated in
this paper.

Index Terms Single Phase Capacitor Run Induction
Motor (SCRIM), Perturb and Observe (P&O technique),
Trickeys Balanced Approach, Optimal Design, Steady State
Model.
I. INTRODUCTION
Numbers of single phase induction motor are being
manufactured every year in the country. These motors are
very popular in the early 1930s for application requiring
high starting and running torques. These motors are very
widely used in the industry especially in fractional kilowatt
range because of their size, cost, weight, reliability and ease
of maintenance. They are extensively used for electric drive
for low power constant speed applications such as machine
tools, domestic appliance, agricultural machinery and other
heavy-duty uses in circumstances where a three phase
supply is not readily available. Of all types of single phase
induction motor, the capacitor run induction motor is the
most popular and widely used because of their good starting
and running characteristics. [1- 5]
In general, Single phase induction motor is working in low
efficiency because of their high copper loss, improper
design of auxiliary winding and rude capacitance value. This
paper discusses a new approach for the design optimization
of single phase capacitor run induction motor using Perturb
and Observe Technique for efficiency enhancement.


Author of this paper is with the Department of Electrical and Electronics
Engineering, School of Engineering, Amrita Vishwa Vidyapeetham
Univesity, Ettimadai, Coimbatore 641 105. phone: 0422 2652422e-mail:
sundaratamil@rediffmail.com.

II. OPTIMAL DESIGN OF SCRIM
The efficiency of the motor depends on active volume of the
material, ie, D
2
L. The value of D
2
L can be calculated for
various values of D and L. By using P & O technique the
optimal values of D and L combination is selected to
achieve maximum efficiency. Initially, stator core stamping,
rotor core stamping, main winding, auxiliary winding and a
capacitor is designed for the ratting of 75W, 220V, 50Hz, 4
pole capacitor run induction motor suitable for fan type
load. D and L values are decremented and incremented step
by step accordingly to achieve the maximum efficiency.
Various steps involved in the design of the motor is
explained clearly in the following figure 1.





































Fig. 1: Various Steps Involved in the Design of SCRIM
Kumaravel S
DESIGN OPTIMIZATION OF SINGLE PHASE CAPACITOR
RUN INDUCTION MOTOR
Performance
calculation

new
>

old

old
=
new

Print Result
Stop
D = D
L = L +
Start
Read the input parameters
Design of Stator Core, Rotor
Core, Main winding and
Die-cast rotor
P
rated
=
P
calc
Design of Auxiliary winding
and Capacitance value using
Trikeys Balanced Approach
A B
A B
XXXII NATIONAL SYSTEMS CONFERENCE, NSC 2008, December 17-19, 2008
839
III.STEADY STATE MODEL OF SCRIM
A. Mathematical Model of SCRIM
The steady state model of single phase capacitor run
induction motor is developed on the basis of balanced two-
phase machine model as shown in figure 2. The machine
consists of balanced two-phase windings on both stator and
rotor and a uniform air gap.

The stator windings are designated D and Q, and the rotor
windings and . The axis of the -phase winding and
that of the D winding are at an angle which increases as
the rotor revolves in a counter-clockwise direction. is
thus a function of time and dt d , which will again be
written
.
is the angular velocity of the rotor relative to the
stator.


Fig. 2: Balanced Two-Phase Machine with Uniform Air-gap
The following differential equation describing the operation
of two-phase induction motor with all the variables referred
to stator and is given below:
( ) ( )
( ) ( )
(
(
(
(
(
(

(
(
(
(
(
(

(
(
(
(
(

+
+
+
+
=
qr
i
dr
i
a
i
m
i
D
r
X
r
R s
r
X D
m
X
s
a s
m
X
s
r
X D
r
X
r
R s
m
X
s
a D
m
X
D
m
X
s
a D
a
X
a
R
D
m
X D
s
X
s
R
a
v
m
v
1 1
1 1
0 0
0 0
0
0
The above equation can be simplified and rewritten in state-
space matrix form as:
| |
(
(
(
(
(
(

(
(
(
(
(
(

=
(
(
(
(
(
(

1
2
1
2
1
0
0
0
1
2
1
2
1
c
V
r
V
r
V
s
V
s
V
A
a
v
m
v
c
V
r
V
r
V
s
V
s
V
D

Where
;
1 dr
i
m
X
m
i
s
X
s
V + =


;
2 qr
i
m
X
s
a
a
i
a
X
s
V + =

;
1 m
i
m
X
dr
i
r
X
r
V + =

;
2 a
i
m
X
s
a
qr
i
r
X
r
V + =


; /
1 c
X
c
v
c
V =

| | A is a 5x 5 matrix and is given by:

( )
( )
(
(
(
(
(
(
(
(

0
2
0
2
0
0
2
1
2
0
0 1
1
0
1
2
0
2
0
0 0
1
0
1
K
m
X
s
a K
r
X
K
a
X
r
R s K
m
X
r
R
s
a
s K
s
X
r
R K
m
X
r
R
c
X K
m
X
a
R
s
a K
r
X
a
R
K
m
X
s
R K
r
X
s
R

where, K
1
and K
2
are the constant expressed as follows,
|
.
|

\
|

=
2
1
1
m
X
r
X
s
X
K
and
( )
2 2 2
1
m s r a
X a X X
K

=
The expressions for the 2-phase (main, auxiliary, rotor direct
and quadrature) currents in terms of the new vectors are
given by:
2
).
2
(
1
).
1 1
(
2
).
2 2
(
1
).
1 1
(
K
s
V
m
X
s
a
r
V
a
X
qr
i
K
s
V
m
X
r
V
s
X
dr
i
K
r
V
m
X
s
a
s
V
r
X
a
i
K
r
V
r
X
s
V
r
X
m
i
=
=
=
=

The expression for the capacitor voltage
c
v is given by:
c
X
c
V
c
v
1
=
The expression for the electromagnetic torque is
given by:
) (
dr
i
a
i
s
a
qr
i
m
i
m
X
e
T =

This developed mathematical model is simulated in
MATLAB/SIMULINK platform. Figure 3 shows the layout
of developed model simulation in MATLAB/ SIMULINK
platform.

Fig. 3: Layout of Developed Model of Single Phase Capacitor Run
Induction Motor in MATLAB/ SIMULINK Platform
IV.DESIGNED OPTIMAL PARAMETERS OF RATED
SPCRIM
Different parameters of optimal capacitor run induction
motor is found by the developed algorithm using P&O
Technique. Table 1. shows the important parameters of the
motor which is designed optimally using P&O Technique.
TABLE.1
S.n Symbol Parameter Value
1 D Stator Outer diameter 3.5
2 D
1
Stator inner diameter 1.8
840
3 L
1
Stator Core Length 0.8
4 g Air Gap Length 10mm
5 S
1
No; of Stator Slots 24
6 D
2
Rotor Outer diameter 1.79
7 S
2
No; Rotor Slots 18
8 C
1
No; Main wind conductors 6718
9 d
1
Wire cage of C
1
(SWG) 32
10 C
r
No; Rotor Bars 18
11 a Turns Ratio 1.12
12 C
2
No; Auxiliary wind. Condu. 7524
13 d
2
Aux. Winding cage (SWG) 36
14 X
c
Capacitive Reactance 1498
V.FABRICATION OF DESIGNED MOTOR
A. Selection Of Motor Stamping
In practice, optimally designed motor is difficult to
fabricate. Because it require more dying and manufacturing
cost, when single number is concern. So, the different
standard stampings available in the market are collected.
Different design parameters like outer diameter, inner
diameter, number of slots, width of slots, etc., are measured
for the collected stampings. Performances of the collected
stamping are analyzed using the dedicated software by
tacking the above measured values as reference and
obtained performances are compared. In the comparison, the
performance of AL3 stamping is suitable for our design. The
fabrication work is carried out for single phase, 75 W, 220
V, 50 Hz, 4 pole capacitor run induction motor using the
selected standard AL3 stamping. Figure 4 shows the AL3
stamping.


(a) (b)
Fig. 4: AL3 stamping (a) Stator (b) Rotor
B. Fabrication of Aluminum die-cast rotor
Stator and rotor core are fabricated with a core length of
0.8cm by silicon steel (hot rol) using AL3 stamping.
Aluminum die-cast rotor is made by die-casting melted
aluminum conductor over the fabricated rotor core. After
fabricating a die-cast rotor, a suitable rotor shaft should be
designed in AUTO CAD software. Figure 5.a shows rotor
shaft drawing for a fabricated aluminum die-cast rotor.
According to the drawing rotor shaft is manufactured and

(a) (b)
Fig. 5: Aluminum Die-Cast Rotor (a) Shaft Drawing (b)Fabricated
Aluminum Die-Cast Rotor
then integrated with aluminum die-cast rotor and fine
finishing process is carried out. Balance test is conducted
over the rotor to reduce the vibration during normal
operation. Suitable bearings are selected and connected at
two ends of the rotor. Figure 5.b shows the fabricated
aluminum die-cast rotor.
B. Main And Auxiliary Winding
According to the design 32 SWG, silicon cotton enamel
copper wire with 8 coils and are distributed by two coils per
pole as one inner coil and an outer coil. Outer and inner
coils wound with 338 turns and are inserted with a coil span
of 1-6 and 2-5. For the auxiliary winding, 36 SWG, silicon
cotton enamel copper wire is selected. Auxiliary winding
has 4 coils; each has 940 turns and is inserted in stator slot
with a coil span of 1-6. Figure 6.a shows the designed main
and auxiliary winding and Figure 6.b shows the fabricated
main and auxiliary winding.

(a) (b)
Fig. 6: Main And Auxiliary Windings (a) Designed Motor
(b)Fabricated Motor

V. EXPERIMENTAL INVESTIGATION OF THE
FABRICATED MOTOR
The fabricated motor is tested in the laboratory by applying
220V, 50Hz, single phase AC supply as shown in figure 7.
The performance of fabricated motor is computed and
results are compared with simulated results of the designed
motor. Table 2 shows the comparison of different
parameters of both simulation and experimental results.
841

Fig. 7: Experimental setup of the fabricated motor
Different waveforms such as motor terminal voltage, input
current, main winding current, auxiliary winding current and
capacitor voltage are observed using digital C.R.O. and the
observed wave forms are reproduced in figure 8. Figure 8
also shows the different output waveform comparison
between simulated and experimental results. It can be seen
that the both the waveforms are resemble each other.
Observed waveforms and the tabulated results prove that,
the fabricated motor is working with enhanced efficiency.
The comparison is made between fabricated motor and
existing motor in table 2. It also proves that the new
fabricated motor is better in the efficiency than existing
motor.





(a) (b)
Fig. 8: Computed Wave Forms (a) Simulated Motor (b)Fabricated
Motor
VI. CONCLUSION
In general, Single phase induction motor is working in low
efficiency because of their high copper loss, improper
design of auxiliary winding and rude capacitance value. This
paper discusses a new approach for the design optimization
of single phase capacitor run induction motor using Perturb
and Observe Technique for efficiency enhancement. The
observed wave forms and test results prove that the designed
motor is operating with improved efficiency compared to
the existing motor.

Kumaravel S was born in veerasingampettai,
Thanjavur (dist), Tamilnadu at 15.07.1981. He
completed his B.E (EEE) from Bharathidasan
University, Tiruchirappalli, Tamilnadu during May
2002 and M.tech (Power Systems) from National
Institute of Technology, Tiruchirappalli during June
2007. So for he is having 6 and half years of
teaching experience.
After his graduation, he worked as a lecturer at M.Kumarasamy College of
Engineering, Karur for 5 years. At present he is with School of engineering,
Amrita Vishwa Vidyapeetham University, Ettimadai, Coimbatore,
Tamilnadu from June 2007. He has presented technical papers two in
International Conference and four in National Conference. His area of
interest is in the field of Incorporation of power converters in renewable
energy sources. He is a life member in I.S.T.E
REFERENCES
[1] Huang, H., Fuchs, E.F., White, J.C. (1988), "Optimal placement of run
capacitor in single phase induction motor design", IEEE Transactions on
Energy Conversion, Vol. 3 No.3, pp.647-52.
[2] Huang, H., Fuchs, E.F., Zak, Z. (1998b), "Optimization of single phase
induction motor design part-I formulation of the optimization technique",
IEEE Transactions on Energy Conversion, Vol. 3 No.2, pp.349-56.
[3] Subramanian, S., Bhuvaneswari, R. (2005), "Optimization of single-
phase induction motor design using evolutionary programming", Journal of
Systems Science and Engineering-PARITANTRA, Vol. 12 pp.30-7.
[4]Crystal.G.Veinott, (1959), Theory and Design of Small Induction
Motors, McGRAW-HILL Book Company, INC, Newyark, I Edition, Page
262-429.
[5] R.K.Agarwal, (2000), Principles of Electrical Machine Design,
S.K.Kataria & Sons, Delhi, IV Edition, Page 366-398.
[6] Stephen D. Umans, Steady-State, Lumped-Parameter Model for
Capacitor-Run, Single-phase Induction Motors, IEEE Transactions on
Industry Applications. Vol. 32, No. 1, Januaryfebruary 1996
[7] D. P. Hohm and M. E. Ropp, Comparative Study of Maximum Power
Point Tracking Algorithms, Progress In Photovoltaics: Research And
Applications Prog. Photovolt: Res. Appl. 2003; 11:4762
[8] S.Kumaravel, Optimal Design and Fabrication of Single Phase
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2008:Volume 3, PP. 79-83.
842
Table 2. Performance of Simulated, Experimented and Existing Motor
Design
parameters
Simulation Result Experimental Result Existing Motor
main
r
142.37
173.84 182.120
main
X
177.97
183.8 310.200
aux
r
201.10
194.64 436.100
aux
X
205.22
209.7 309.700
c
X
1498.20
1450.23 1458.2
2
r
65.65
100.200 100.200
2
X
122.43
250.400 292.00
m
X
1408.36
1500 1250.8
m m
I
0.198 -36.03
0.114 -34.33 0.137 -31.43
a a
I
0.221 35.30
0.274 30.67 0.244 14.80

s
I
0.341 1.87
0.339 12.83 0.353 -1.43
cos
0.9995
0.9750 0.999
in
P
75.05
72.75 77.73
out
P
55.83
50.828 43.854
s
0.06
0.07 0.120
N
1410
1395 1382
T
0.378
0.343 0.297

74.40
69.90 56.42