AN INVESTIGATION THE EFFECT OF STATOR SLOT OPTIMIZATION IN 0.5HP THREE PHASE INDUCTION MOTOR VIA FEM.
ABSTRACT: A study of stator slot design for induction motor is necessary in order to additional improvement of efficiency and reduces the winding loss. By using FEM, the motor parameters as well as the losses and the efficiency between the different stator slot sizes is estimate and the result is presented. The results shows that the optimal stator slot model which is the stator with slot size 8mm has lower winding loss and total loss compared to initial stator slot model which is the stator with slot size 6mm. Thus, a 2.92% of the efficiency was improved as reduction of winding loss and total loss at the optimal stator slot model.
Induction machine is the most used of all electric motors. It is generally easy to build and cheaper than corresponding dc or synchronous motors. The induction motors is rugged and require little maintenance . The ac induction consists of stationary member, called the stator and the rotating member, called the rotor. AC power is used to energize the stator windings.
A study of stator slot design for induction motor is necessary in order to additional improvement of efficiency and reduces the winding loss.
The finite element method is now well documented. It allows the estimation of the induction motor parameters with a reasonably high accuracy. In this investigation, finite element method (FEM) is used as the main tool in the estimation of motor parameters as well as the losses and the efficiency between the different stator slot sizes.
2. MATERIAL AND METHODS
2.1 Design Specification
Two models of the three phase induction motor stators between different stator slot size used in this investigation. The initial model is the stator with slot size 6mm and the optimal model is the stator with slot size 8mm as in Fig. 1 and Fig. 2.
Table 1 shows the stator specification of the induction motor. This parameter is important as it is used to simulate the FEM software. From this, the result of motor parameters as well as the losses and the efficiency of the two stator slot design are obtained. The stator teeth are design with parallel sides to avoid localized saturation within the teeth .
Table: 1 Design specification of induction motor
Electrical steel material thickness [mm]###0.35
Outer diameter of stator[mm]###180
Inner diameter of stator[mm]###68
Stator slot width of initial model [mm]###6
Stator slot width of optimal model [mm]###8
Number of Stator slot###24
3. RESULTS AND DISCUSSION
Finite element analysis (FEA) is used to examine the stator copper loss and efficiency between two stator models. The results of comparison between two different stator slot size which is 6mm and 8mm is described in many aspects from the simulation of FEM is shown below.
3.1 Equivalent Circuit
The parameters of the 0.5HP induction motor equivalent circuit of two different stator slot size are shown in Fig. 3.
3.2 Equivalent Circuit Analysis
The results of AC analysis for stator slot size 6mm and 8mm are shown in Fig. 4 and Fig. 5 respectively. The tests are based on FEA solves and include accurate estimation of stator copper loss or winding loss and also the efficiency.
Based on the result as shown in Fig. 4 and Fig. 5, graphs such as the loss (Watts) vs. speed (rpm) are plotted as shown in Fig. 6. In this investigation, by increasing the stator slot size from 6mm to 8mm, 14.27% of stator copper loss can be reduced. This is due to the increase of the stator slot size will decrease the resistance of the stator coil, thus the stator copper loss is reduced . This loss will contribute to the variation in the motor efficiency.
The reduction of stator copper loss can improve the motor efficiency as shown in Fig. 7. So, even a minor improvement, this can save several amount of energy that was consumed by the induction motor .
From the graph in Fig. 7, the efficiency of stator slot size 8mm is 81.16% which is better than efficiency of stator slot size 6mm which is 78.86%. This is due to the losses of stator slot size 8mm is lower than 6mm, thus the efficiency is improved. In this investigation, the increase in stator slot size from 6mm to 8mm can not only reduce the stator copper loss, but also a 2.92% of the efficiency can be improved. Even the efficiency increase of 1 or 2%, it has a crucial effect on the performance of home appliances, as well as on energy savings worldwide .
The effect of stator slot optimization in 0.5hp three phase induction motor via FEM was proposed. We may conclude from the results that the optimal stator slot model which is the stator with slot size 8mm has lower winding loss and total loss compared to initial stator slot model which is the stator with slot size 6mm. Thus, a 2.92% of the efficiency was improved as reduction of winding loss and total loss at the optimal stator slot model.
The authors wish to thank Universiti Kuala Lumpur British Malaysian Institute for the technical and financial support.
 Hubert, C. I., "Electric Machines Theory, Operation, Application, Adjustment, and Control", Prentice Hall Columbus, Ohio, (2002).
 S. Ho, "Analysis and Design of AC Induction Motors with Squirrel Cage Rotors", University of New Hampshire, (1996).
 Seok-bae Park, H.-b. L. a. S.-y. H., "Stator Slot Shape Design of Induction Motors for Iron Loss Reduction", IEEE Transactions on Magnetics, 31(3), 1995, pp. (2004-2007).
 I. Daut, S. Nor Shafiqin, N. Gomesh, Y. Yanawati, M. Abdullah, I. Pungut, "An Investigation on Stator Copper Loss by using Different Stator Slot Size", 3rd International Conference on Computer and Electrical Engineering (ICCEE 2010), Chengdu, China, (2010).
 Gun Hee Jang, and S. J. Park, "Charecterization of a single-phase induction motor due to the effect of slot opening", IEEE Transactions on Magnetics, Vol 40, No. 4, (2004).
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|Date:||Oct 31, 2017|
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