In a motor, in the middle, coils are used and they are magnetized when AC current flows through them.I have found permanent magnets are being placed fixed with some distance around these coils for producing deflection and thus the motor runs in some motors.Does a 7.5 HP AC motor also has permanent magnets?
7.5 HP AC motor does not need any permanent magnets. Same to all different kinds of AC motor, they do not need permanent magnets. But a small AC generator needs permanent magnets.
without magnets, no motor. The electricity provides the electromagnetic force to turn it
Unlikely, most ac motors are induction motors. If your 7.5HP motor is 3 phase, which is most likely as it seems large for single phase, the rotor will be what's called squirrel cage. This is aluminum bars made into a cage. The rotating magnetic field in the stator induces a current into the rotor, the same way a transformer does but the resulting magnetic field produced is opposite to that of the stator causing the rotation. Smaller single phase motors may contain windings and there are a number of different types of single phase motors. Larger 3 phase motor may be wound rotor so that some resistances can be added through slip rings for starting or speed control. There is a type of ac motor called synchronous motor. The rotor is powered by dc and is, in effect, a large magnet but this type of motor is not self starting and uses some other method to get up to speed before the dc is applied.
