The most common starting method of the synchronous motor is as if it were an asynchronous cage motor, that is, Gates B94 to excite it by feeding the field winding with direct current in order to synchronize it. The magnetic field created by the field winding is intertwined with the rotating magnetic field of the armature, generating the pull-in-torque conjugate and causes the rotor to follow the rotating field of armature (stator), moving at synchronous speed. This transient phenomenon is called “synchronization.”
To ensure starting and synchronizing of the synchronous motor, analysis of the starting torque curve of the motor must always be accompanied by analysis of the strength-coupled curve of the load and the inertia of the motor and load. The armature is connected to an alternating voltage network and it induces an induced current in the motor cage, which generates the starting torque as an asynchronous motor. The rotor accelerates close to the synchronous speed without reaching it. When the rotor speed is about 95% of the synchronous speed, the field winding is fed with direct current.