EC Motors: Internal Rotor / External Rotor Design


There exist two basic design versions:


Internal rotor motors have a closed housing and the magnets are mounted on the shaft.

They have low inertia and can reach high speed.

Application is for high dynamic requirements, usually in combination with gearboxes.


Closed housing enables high IP code of protection
ec motor

External rotor motors have no closed housing and their magnets are mounted to a moveable part of the housing.
This movable housing part transmits the torque to the shaft.

Due to the large distance of air gap from shaft centre and large length of air gap they generate quite high torque, but at low speed.

Usually they are used for direct driving, without need for gearboxes.

The large inertia results in low dynamic ability, but enables low speed ripple and smooth running.

Only low IP code of protection possible.

ec motor




Example: Internal rotor EC motor

ec motor




External rotor EC motor

ec motor