Computational Design and Analysis of Core Material of Single-Phase Capacitor Run Induction Motor

Mohd. Afaque Iqbal et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 7( Version 3), July 2014, pp.20-25
www.ijera.com 20 | P a g e
Computational Design and Analysis of Core Material of Single- Phase Capacitor Run Induction Motor Gurmeet Singh*, Gurlad Singh**, Mohd. Afaque Iqbal*** * (Department of Electrical & Instrumentation, SLIET Longowal University, Punjab-148106) ** (Department of Electrical Engineering, Aryabhatta group of institutes, Barnala, Punjab-148101) *** (Department of Electrical & Instrumentation, SLIET Longowal University, Punjab-148106) ABSTRACT A Single-phase induction motor (SPIM) has very crucial role in industrial, domestic and commercial sectors. So, the efficient SPIM is a foremost requirement of today’s market. For efficient motors, many research methodologies and propositions have been given by researchers in past. Various parameters like as stator/rotor slot variation, size and shape of stator/rotor slots, stator/rotor winding configuration, choice of core material etc. have momentous impact on machine design. Core material influences the motor performance to a degree. Magnetic flux linkage and leakage preliminary depends upon the magnetic properties of core material and air gap. The analysis of effects of core material on the magnetic flux distribution and the performance of induction motor is of immense importance to meet out the desirable performance. An increase in the air gap length will result in the air gap performance characteristics deterioration and decrease in air gap length will lead to serious mechanical balancing concern. So possibility of much variation in air gap beyond the limits on both sides is not feasible. For the optimized performance of the induction motor the core material plays a significant role. Using higher magnetic flux density, reduction on a magnetizing reactance and leakage of flux can be achieved. In this thesis work the analysis of single phase induction motor has been carried out with different core materials. The four models have been simulated using Ansys Maxwell 15.0. Higher flux density selection for same machine dimensions result into huge amount of reduction in iron core losses and thereby improve the efficiency. In this paper 2% higher efficiency has been achieved with Steel_1010 as compared to the machine using conventional D23 material. Out of four models result reflected by the machine using steel_1010 and steel_1008 are found to be better.
Keywords - Single-Phase induction motor, core material, Maxwell 15.0
I. Introduction
Induction motors are widely used in commercial and industrial sectors due to their robustness, simplicity and cost-effectiveness [1]. SPIM is one of the types of induction motors which have a crucial role in domestic, agricultural and industrial sectors. With the growing demand and importance, SPIM has different merits from other motors i.e. ease of maintenance, reliable in size, easy operation and good running characteristics with low cost. A large number of fractional kW ac motors are designed to operate from single-phase supply. In general use, fractional kW motors used about 80% of the total annual production. A single-phase motor is not self- starting operates on poor power factor, lower capacity and reduced efficiency. It has pulsating air- gap field. On the basis of starting types, SPIM is classified as: (1) Split-phase (2) Shaded pole (3) Repulsion type. Split-phase is further divided into two categories as: (a) Resistor-split phase (b) Capacitor-split phase. Capacitor-split phase is categorized into three types as: (i) Capacitor-start (ii) Capacitor-Run (iii) Capacitor-start/run [2]. In this paper, capacitor-run motor has been investigated.
Where no three-phase lines (commercial & agricultural) and low powered loads are present, Capacitor-run motors are mostly used in that fields. In this world, many regions have only single-phase power which means that a large quantity of single- phase motors is a primary requirement of today’s market. So it is necessary to reduce the energy consumption by enhancing the performance of these motors [3]. Capacitor-run motors are widely used in domestic as well as in industrial fields. This motor has oval shaped rotating magnetic field in air-gap which results poor starting torque performance. However, it has better running performance. Currently, the optimization work focus on the starting performance improvement. There are various parameters consisting in motor design and the objectives functions and constraints for optimization are limited. So, it is impossible to take all parameters into account at same time [4].
With the increasing demand of oil and enhancement in electrical energy cost including relative development in the material technology, more attention towards the high efficient induction
RESEARCH ARTICLE OPEN ACCESS

motors has been paid by designers. With the growing demand of Single-phase induction motor (SPIM) in industrial and commercial sectors, its design optimization becomes an immense importance. The design optimization has crucial influence in obtaining improved model of SPIM. In the past, major research work has been carried out for optimization of core material, stator winding, slot variation and slot design but optimization for core material of both stator and rotor has paid least emphasis. Core material is one of the parameter influences the performance of the SPIM. Using Ansys Maxwell 15.0, this paper designs the optimal model in terms of the choice of core material. Four models are simulated by changing the core material of both stator and rotor. D23, M19_24G, steel_1008 and steel_1010 are used as core material in the proposed work. All models are simulated and investigated along with conventional model and the calculated results are compared to each other. Model-4 is the best optimal solution with best results out of all simulated models as well as conventional model.
II. Ansys Maxwell 15.0
Rmxprt is a common function package of the two dimensional electromagnetic field analysis software among MAXWELL, produced by Ansoft Corp. Maxwell 15.0 is professional design software of rotary motor, which can calculate the performance quickly of a variety of motor, such as induction motor, synchronous motor, electronic or mechanical commutator motor, etc. RMxprt can evaluate thousands of design projects quickly, and can optimize the pre-choice project. After optimal design, it can automatically generate a reasonable two/three- dimensional finite element analysis model according to the symmetry. The Rmxprt software provides an effective tool for engineers to evaluate and balance the project in production design process [4].
III. Proposed Model
The research work was carried out to investigate the performance of the machine under test with different core material of both stator as well as rotor core. The other parameters like size of machine, dimension of stator and rotor, slot configuration, winding material, connections etc. are kept unchanged. Four models are simulated as given in table 1. TABLE 1: Different types of core material
Models
Core-Material
Model-1
D23
Model-2
M19_24G
Model-3
Steel_1008
Model-4
Steel_1010
IV. Motor Geometry
In this work, squirrel cage motor with two-pole, 24 stator and 18 rotor slots is used as conventional model. The overview of conventional model of the machine is shown in fig. 1 [4]. However, the core material of designed motor has been changed in the present work and all four models are simulated.
Fig. 1: Overview of designed model In this paper, the motor performance is analyzed by changing the core material of stator and rotor but other parameters like size and number of slots, inner and outer diameters, type of slot all are kept unchanged. Four type of core material has been selected for the simulation work after analyzing their magnetic, electric and mechanical properties in which model-1 presented the conventional design. The specification of machine used under test is given in table 2 and the design parameters for stator and rotor are shown in table 3 and table 4 respectively [4]. TABLE 2: Specification of machine under test
Parameters
Specification
Rated Power Output
250 W
Rated Voltage
220 V
Number of Poles
2
Rotor Position
Inner
Type of load
Constant
Operating Temperature
75oC
Capacitor
8 μF
TABLE 3: Design parameters of Stator
Parameters
Specification
Number of stator slots
24
Outer diameter of stator
120 mm
Inner diameter of stator
60 mm
Length of stator core
45 mm
Stacking Factor of stator core
0.95
Top Tooth Width
4.01875 mm
Bottom Tooth Width
7.5842 mm

Main-Phase Wire Diameter
0.6 mm
Aux.-Phase Wire Diameter
0.53 mm
Slot Insulation Thickness
0.2 mm
Layer Insulation Thickness
0.2 mm
Limited Slot Fill Factor
75 %
Wire Resistivity
0.0217 ohm- mm2/m
Auxiliary Wire Resistivity
217 ohm- mm2/m
TABLE 4: Design parameters of Rotor
Parameters
Specification
Number of rotor slots
18
Outer diameter of rotor
59.4 mm
Inner diameter of rotor
20 mm
Air-gap
0.6 mm
Height of End Ring
14.8 mm
Width of End Ring
7.9 mm
Bar Resistivity
0.0434783 ohm- mm2/m
End Ring Resistivity
0.0434783 ohm- mm2/m
Rotor Core Length
45 mm
Rotor Stacking Factor
0.95
V. Dimensions of slot used
In this type of slot configuration, the geometric parameters of stator and rotor slots are given as table number 5and 6 respectively. The shape of the slot both stator and rotor are shown in fig. 2 and 3 respectively. The two dimensional overview obtained in Ansys Maxwell simulation is shown in fig. 4.
Fig. 2: Stator slot Table 5: Geometric parameter for stator slot
Parameter
Dimension
Hs0
0.7 mm
Hs2
8 mm
Bs0
2.5 mm
Bs1
4.9 mm
Bs2
3.5 mm
Fig. 3: Rotor slot Table 6: Geometric parameter for rotor slot
Parameter
Dimension
Hs0
0.2 mm
Hs1
0.2 mm
Hs2
4.6 mm
Bs0
0.1 mm
Bs1
5 mm
Bs2
3 mm
Fig. 4: Overview of stator and rotor slot Model-1 with D23 core material consider as conventional model. Model-2 use M19_24G, Model- 3 use Steel_1008 and Model-4 use Steel_1010 as core material. After simulation work, results has been calculated and comprised.
VI. Simulation Results
The investigations and analysis of single phase capacitor run induction motor has been carried out by changing the core material of both stator and rotor. The simulation results for all four models are tabulated below in table 7. Table 7: Comparison of simulation result
Parameters
Model- 1
Model-2
Model- 3
Model-4
Capacitor Loss (W)
3.8285
3.8117
3.86648
3.7824
Copper Loss of Stator Winding (W)
28.413
28.288
27.358
29.12

Copper Loss
of Rotor
Winding (W)
21.529
20.51
3
22.7337
18.10
0
Iron-Core
Loss (W)
13.719 88.67
9
0.00032
5871
0.000
32309
5
Frictional and
Windage
Loss (W)
19.041
19.03
3
19.0531
19.01
2
Total Loss
(W)
86.530 80.32
5
73.0116 70.01
5
Input Power
(W)
336.60 330.4
0
322.854 320.0
9
Output Power
(W)
250.07 250.0
8
249.843 250.0
7
Efficiency
(%)
75.5 77 78 78.75
Power Factor 0.9803 0.986
4
0.967 0.998
4
6.1 Variation of efficiency with speed for different
models
The variation of efficiency with speed is for
Model-1 which uses core material as D23 is given in
fig. 5 the efficiency recorded 75.5% at speed 2800
RPM.
Fig. 5: Curve of efficiency of D23 design
For model-2 the variation of efficiency with
speed is shown in fig. 6 the maximum efficiency
recorded 77% at speed 2850 RPM.
Fig. 6: Curve of efficiency of M19_24G design
Similarly the variation of efficiency with speed
for using core material Steel_1010 is plotted using
graphical output in the software is shown in fig. 7. In
this the maximum efficiency recorded is 78% at
speed 2850 RPM.
Fig. 7: Curve of efficiency of STEEL_1008 design
Variation of efficiency with speed for model-4 is
graphically presented in fig. 8. The maximum
efficiency recorded is 78.75% at speed 2800 RPM.
Fig. 8: Curve of efficiency of STEEL_1010 design
VII. Discussion
The analysis of the outcome of the results
obtained in all the four models gives reflection of the
nature of core material on the performance of
machine.
The efficiency of the machine in model-1 using
D23 as core material is recorded as 75.5% where as it
is recorded 78.75% in the model-4 in which
Steel_1010 used as core material. This improvement
in the efficiency is because of the better magnetic
properties, higher operating flux- density and
decrease in leakage flux of steel_1010 in comparison
to other materials. The efficiency bar graph of all
four models is shown in fig. 9.
Fig. 9: Bar graph of efficiency
The rotor reactance offered in the model-4 is
12.37 ohm which is minimum in all the four models
which reflects that the rotor reactance is directly
0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00
n (rpm)
0.00
12.50
25.00
37.50
50.00
62.50
75.00
(%)
ANSOFT
Curve Info
Efficiency
0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00
n (rpm)
0.00
12.50
25.00
37.50
50.00
62.50
75.00
(%)
ANSOFT
Curve Info
Efficiency
0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00
n (rpm)
0.00
12.50
25.00
37.50
50.00
62.50
75.00
(%)
ANSOFT
Curve Info
Efficiency
0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00
n (rpm)
0.00
12.50
25.00
37.50
50.00
62.50
75.00
(%)
ANSOFT
Curve Info
Efficiency

affected by magnetic properties of the core material
of rotor core. This will reduce the percentage leakage
reactance of flux and therefore improve the
efficiency. Similarly the magnetic reactance recorded
to be 281.56 ohm in the model-4 using steel_1010 is
minimum as compared to other models. This affects
the magnetizing component of current as well as the
power factor of the machine in the results the
maximum improvement in the power factor recorded
as 0.998 in the model-4, the best one in all the four
models.
The power factor bar graph plotted for all the
four models shown in fig. 10. The poor power factor
of model-3 is because of the improper orientation of
the rolled steel material. The highest power factor
recorded in the model-4 which uses steel_1010 has
been recorded. This achievement in the power factor
is on the ground of improved magnetic properties.
Fig. 10: Bar graph of power factor
This improvement in power factor has reduced
the overall running current proportionally. The
running current in the model-4 is 1.45 ampere which
is lowest level as compared to 1.56 ampere in the
model-1 the highest one.
The bar graph in fig. 11 presented stator line
current drawn by the machine in each simulation
model.
Fig. 11: Bar graph of Stator line current
This reduction in running current reduces copper
loss and maximum temperature level and is better for
insulation co-ordination of stator winding as well as
rotor winding. Though may the overload capacity is
not much more affected by the core material but there
is an overall improvement in the overload capacity of
the machine as compared to base model it is
approximately recorded up to 200% in all the models.
The rotor leakage reactance is the function of
magnetic properties of core material with the
upgrading of the magnetic properties of steel_1010
reduction in leakage reactance as shown in bar graph
fig. 12.
Fig. 12: Bar graph of rotor leakage reactance
The fact of the core material on the starting
torque has also been observed. In the base model the
starting torque developed is 0.379 N/M In the model-
1 develops starting torque 0.485 N/M. In the model-3
the starting torque developed is recorded 0.480 N/M
and that in model-4 it is highest 0.488N/M. This
improvement in the starting torque of the machine
with the steel_1010 is because of the magnetic
properties of the material. For the same starting
torque developed the magnetic flux density required
in the model-4 is minimum or for the same torque,
same flux density proportionally core size is reduced.
The model-4 is the optimized model out of the
four models investigated in the paper.
VIII. Conclusion
Selection of core material of the motor
significantly affects the performance of motor. The
flux linkage and leakage both are directly concerned
with nature of core material. Today, D23 is used as
core material. Working flux density of D23 is 1.60
tesla and maximum flux density is 1.64. The
efficiency of the material which depends upon
hysteresis and eddy current loss partly is affected by
core material. In the simulation work it is observed
that the maximum efficiency of D23 is 75.5% and
total losses are 86.53 watt. The efficiency with
steel_1010 is approx. 3% more than D23. This result
is because of reduced iron core losses. Further
thermal conductivity of steel_1010 is high and rise of
temperature problem also shorted to some extent.
Due to steel_1010 is used as core material over
fluxing is avoided in the core. The mechanical
strength of steel_1010 is higher leads to higher speed.
The simulation work reflects the influence of
magnetic properties of the core material on the
reactance which in turn affects the power factor and
input current and up to certain extent harmonics

level. The steel_1010 offered the least reactance and better results further running current in the model is 1.45 ampere which is less in all the four models. This reduction in running current reduces copper loss and better for insulation co-ordination of stator winding as well as rotor winding. The overall enhancement in the performance of fourth model is on account of the better magnetic properties of the core material which therefore justifies the work that core material plays a significant role in the optimization of induction machine. References [1] G. Lee et al. “Optimal Shape Design of Rotor Slot in Squirrel-Cage Induction Motor Considering Torque-Characteristics”, IEEE Trans. on magnetics, Vol. 49, No. 5, 2013, pp. 2197-2200. [2] S. Sobhani et al. “Optimize efficiency and torque in the single-phase induction motor by adjusting the design parameters”, International conference on Environment and Electrical Engineering (EEEIC-2013), pp. 237-241. [3] M.S. Alshamasin, “Optimization of the Performance of Single-Phase Capacitor- Run Induction Motor” American-Journal of Applied Sciences, 2009, pp. 745-751. [4] Z. Rui et al. “Optimal Design of Single- Phase Induction Motor Based on MAXWELL-2D Rmxprt”, International conference on Electrical machines and Systems (ICEMS-2010), pp. 1367-1370. [5] Claudia A. da Silva et al. “Analysis of Single-Phase Induction Motors with Centrifuged Rotors”, International Electric Machines & Drives Conference (IEMDC- 2013), pp. 1305-1309. [6] Y. Yanawati et al. “Efficiency Increment of 0.5 hp Induction Motor by Using Different Thickness of Rotor Lamination Steel Sheet via FEM” 5th International Power Engineering and Optimization Conference, Malaysia, 2011, pp. 188-192. [7] H. Yoon and C. S. Koh “Influence of Vector Hysteretic Property of Non- Oriented Silicon Steel Sheet on Three-Phase Induction Motor Model” pp. 1-2. [8] G.C. Paap “The analysis of 3-phase squirrel- cage induction motors including space harmonics and mutual slotting in transient and steady state” IEEE Transactions on Energy Conversion, Vol. 6, No. 1, March 1991, pp 69-82.
[9] K.J. Park et al. “Optimal Design of Rotor Slot of Three-Phase Induction Motor with Die-Cast Copper Rotor Cage”, International conference on Electrical machines and Systems (ICEMS-2009), pp. 61-63.
[10] S. Salon, D. Burow, M. De Bortoli, C. Slavik “Effects of Slot Closure and Magnetic Saturation on Induction Machine Behavior” IEEE transactions on magnetics, Vol. 30, No. 5, 1994, pp. 3697-3700.

Computational Design and Analysis of Core Material of Single-Phase Capacitor Run Induction Motor

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Computational Design and Analysis of Core Material of Single-Phase Capacitor Run Induction Motor