Electrical Machines - EE213 - 43 - Single phase induction motors

Single phase induction motors are the most widely used motors for home appliances. This lecture explains the working of a single phase induction motor. The rotor of a single phase induction motor is generally a cage type rotor, similar to the one used in three phase induction motors. The stator has single phase windings which produce a pulsating but stationary stator magnetic field. The stator magnetic field can be decomposed into two rotating magnetic fields, one rotating in clockwise direction and the other rotating in counter-clockwise direction. The motor responds to both the components and overall torque-speed characteristics can be obtained by superposition of torque-speed characteristics by each rotating component. The simple single phase induction motors suffer from two problems, firstly, these are not self starting and secondly, there are high vibrations in the motors due to pulsating induced torque.