The effect of different stator slot size on flux and losses distribution in 0.5 hp induction motor

Abstract

A study of stator slot design is conducted for induction motor in order to improve the efficiency and reduce the losses. In this thesis, the effect of different stator slot size on the flux and losses distribution in 0.5 hp induction motor have been thoroughly investigated via FEM and experimental work. Two stator core models with the slot size of 6 mm and 8 mm have been designed and fabricated in this project. The scope of using FEM reveals parameters such as the stator copper loss, total loss and efficiency. This result is then discussed in terms of differences between two stator slot sizes. The experimental techniques have been performed in order to measure the localised flux density distribution of fundamental and individual harmonic components (odd order) within the stator by using search coil method and the localised power loss distribution throughout the stator core by using the thermistor method. The localised flux density is compared with the magnetic potential line (FEM) in order to verify the similarity of the flux distribution in the stator core. The flux distribution is decreased towards the outer region of the stator core and at the stator teeth; the flux density is much higher than others for both localised flux density distribution and magnetic potential line. The localised power loss distribution is proportional with the localised flux density distribution due to the influence of localised power loss towards the harmonic content of flux distribution. The differences of the stator slot size can affect the magnetic flux density at the stator core. Results shows that the fundamental and the individual harmonic components of in-plane and normal flux density at the stator slot size 8 mm were lower compared to the stator slot size 6 mm. It also reveals that the minimum localised flux density and power loss occurs at 8 mm slot size compare to 6 mm. FEM result shows that increasing the stator slot size 6 mm to 8 mm had improved the motor’s efficiency by 2.92%. Overall concrete result concludes that the 8 mm stator slot does lower the losses and increase the induction motors efficiency.