SAC Synchronous motor is always in a fix state ,The shaft rotation is synchronized with frequency of the supply current. AC cycles of integral number are exactly equal to the rotational period. It has multiple AC Electromagnets on the stator which create a magnets field with which rotate in time with the oscillations of the line current.
It can operate at high speed in both loaded and unloaded conditions.BLDC motors have the highest running torque per cubic inch of any DC motor.BLDC motors do not have brushes, meaning they are more reliable and have life expectancies of over 10,000 hours. It has high life expectancy in continuous running application, no brushes so no spark. Safe for chemical and flammable application. This results in fewer instances of replacement or repair and less overall down time.Inner rotor Brushless DC motors have low rotor inertia, allowing them to accelerate, decelerate, and reverse direction quickly.