i want the difference in working operation at the rotor side as at synchronous motor rotor feeded by D.C current but at induction by A.C
I really like teressa's answer - very long and complete. In short synchronous motor's run in lock step with the rotating magnetic field produced by the AC field winding. There may be a phase difference - lead or lag, however the frequency with which the rotor spins is locked to the frequency of the AC power. Asynchronous motors run at a frequency not locked to the AC power, either faster or slower depending on whether power is being generated or used.
Synchronous AC motors run at a speed fixed by the input line frequency. Typically 60 Hz in the USA. Run a clock with the sync motor from the USA in England and it runs slow because they use 50Hz. Asynchronous motors run at whatever free-run speed they feel like, and slow under load. A DC wound hand-drill is such a motor, runs pretty fast till you start drilling, then it slows down. A synchronous motor will develop maximum power at its' designed speed, try to slow it down and it puts out more torque. Slow it down by overload, it doesn't create more power, it just creates more heat. An Async motor creates highest torque at stall speed, least torque as it approaches maximum speed.
