During working of a permanent magnet synchronous motor, _____.

Question

Question

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SSC JE Electrical 9 Oct 2023 Shift 3 Official Paper-I

stator and rotor both produce rotating magnetic field
stator and rotor both produce constant magnetic field
rotor produces rotating magnetic field and stator produces constant magnetic field
rotor produces constant magnetic field and stator produces rotating magnetic field

Answer 1

The correct answer is option 4.

Permanent magnet synchronous motor

Synchronous motors are the most widely used steady-state 3-phase AC motors, which convert electrical energy into mechanical energy.
This type of motor operates at synchronous speed, which is constant and it is synchronous with the supply frequency and the period of rotation is equal to the integral no. of AC cycles. That means the speed of the motor is equal to the rotating magnetic field.
The permanent magnet synchronous motors are one of the types of AC synchronous motors, where the field is excited by permanent magnets that generate sinusoidal back EMF.
It contains a rotor and stator same as that of an induction motor, but a permanent magnet is used as a rotor to create a magnetic field. Hence there is no need to wound field winding on the rotor.
Instead of using winding for the rotor, permanent magnets are mounted to create a rotating magnetic field. As there is no supply of DC source, these types of motors are very simple and less costly. It contains a stator with 3 windings installed on it and a rotor with a permanent magnet mounted to create field poles. The 3-phase input AC supply is given to the stator to start working.
This type of motor is mainly used in power systems to improve the power factor.