While both AC and DC motors serve the same function of converting electrical energy into mechanical energy, they are powered, constructed and controlled differently.  The most basic difference is the power source. AC motors are powered from alternating current (AC) while DC. motors are powered from direct current (DC), such as batteries, DC power supplies or an AC-to-DC power converter. DC wound field motors are constructed with brushes and a commutator, which add to the maintenance, limit the speed and usually reduce the life expectancy of brushed DC motors. AC induction motors do not use brushes; they are very rugged and have long life expectancies. The final basic difference is speed control. The speed of a DC motor is controlled by varying the armature winding’s current while the speed of an AC motor is controlled by varying the frequency, which is commonly done with an adjustable frequency drive control.