AC motors(Alternating Current motors) have a simple structure and has higher efficiency than the DC
motors(Direct Current motors) when operated at high speed [2]. AC motors also provide more durable
service with a lower cost compared to DC motors [24]. Besides, AC motors can easily be supplied directly
from the grid and therefore they are widely used in industry. However, when it is directly connected to the
grid, traditional AC motor gets the better performance only at the speed near the synchronous speed due
to its working principle [2]. In some low cost applications where only DC is available, e.g. in electrical
vehicles, the usages of AC motors are limited