What The Tech: What is the differ­ence between internal and external rotor motors?

There are different motors and in this video we look at the differ­ence between internal and external rotor motors.

A motor is roughly made up of two compo­nents:
The stator is always the fixed and immov­able part of the device. The stator gener­ates a magnetic field through the current in its wind­ings. This is induced in the rotor. The rotor now begins to move.
If it rotates inside the stator, this is referred to as an internal rotor motor. As these rotors have a smaller diam­eter, the power density is very high and the moment of inertia is low.
This makes the dynamics of these motors partic­u­larly attrac­tive, as the speed and even direc­tion of rota­tion can be changed in millisec­onds, even at the high speeds that a motor like this achieves.

If the rotor rotates around the stator instead, this is referred to as an external rotor motor. The rotor is fitted with a magne­tized ring. There­fore, instead of an axis, the cover or the magnetic ring itself rotates. Since more surfaces of the stator and rotor interact, this type of motor gener­ates a high level of effi­ciency. This means a high motor power with low energy consump­tion.