AC Axial Fan rely on carbon brushes and a commutation ring to switch the current direction, and therefore the magnetic field polarity, in a rotating armature. The interaction between this internal rotor and fixed permanent magnets induces its rotation. In an EC motor, the mechanical commutation has been replaced by electronic circuitry, which supplies the right amount of armature current in the right direction at precisely the right time for accurate motor control. Matters are further simplified by using a compact external rotor design with stationary windings. The permanent magnets are mounted inside the rotor with the fan impeller attached.

Brushless DC motors have been around for many years but there has always been the need for a separate DC power supply. In applications using only an AC supply this introduced added cost and complexity. Then, in 2003, ebm-papst brought out an EC Fan with integrated electronics which could be connected directly to an AC mains supply. In addition to performing the commutation, the electronics convert AC to DC and control the fan speed by regulating the power to the motor.
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