The main feature and working principle of synchronous motor is constant speed . This is also achiev by using constant magnetic field create inside this motor. Synchronus Motor magnatice field is similar to induction motor rotating magnetic field . This magnatic field is generate by stator and the rotor part generate constant magnetic field.Three-phase supply apply in to this synchronous motor and this cause revolving magnetic field inside stator which rotate at synchronous speed. In Synchronous motor the rotor part is excite by direct current power supply so it’s act like a permanent magnet.
Synchronous Motor Construction
The Main construction of synchronous machine are stator and rotor part of the motor.
Stator – Stator part of synchronous machine has three-phase distribute windings or Alternative current supply. Stator part of synchronous machine is much similar to the induction machine. This winding also know as armature winding
Rotor – The rotor part of this machine got DC winding which known as field winding. This winding is normally fed from the external direct current though slip rings. The rotor par of the synchronous machine can also sub divide in to two sub categories such as cylindrical Rotor (Use for High Speed machines) . Salient Pole Rotor ( Use for low speed machines).
There are two main parts consist in this synchronous generator such as Field winding and armature winding.
synchronous Machine windings.
Field Winding– This winding consists the rotating winding par that produce the main magnetic field in to the machine.
Armature Winding– Armature winding is the winding where the main voltage is induced
Basic Working Principle of Synchronous Motor
Stator and rotor part locate magnetically in synchronous motor. So the rotor will rotate the same speed of rotating magnetic field (rmf) of the stator winding of the synchronous motor. So rotor is also runs at synchronous speed. Normally synchronous motors are design to operate under the synchronous speed. The rotational magnetic filed equation of the synchronous motor can give as following.
nm = rate rotation of synchronous machine’s magnetic field (rpm)
fe = electrical frequency/frequency supply (Hz)
P = number of poles in the machine
Normally synchronous motors are not inherently self-starting motor. To make synchronous motor self start the squirrel cage arrangement insert into rotor part of the motor. After inserting squirrel cage arrangement into synchronous motor it start like induction motor. When rotor is rotate on synchronous speed the relative speed of rotating magnetic field and squirrel cage arrangement is zero.
Why Synchronous Motors Use
The main advantage of synchronous speed motor is it can run at constant speed . Its speed not much depend on the load which apply in to this motor. This motor is also got great efficiency and its use for high profession applications. Synchronous machine are use in large power applications due to its unique features . Such as the controllable power factor, higher efficiency under operation and its reliability.