A motor assembly, comprising a brushless DC motor with control electronics which comprises at least two magnetic field sensors adapted to measure magnetic flux from magnetic poles on a rotor in the brushless DC motor. The magnetic field sensors are adapted to determine an angular position of the rotor, with the purpose of controlling the current to the brushless DC motor based on the determined angular position. The brushless DC motor is an external rotor motor comprising an internal stator, and an external rotor having a periphery and an inside, which exhibits a plurality of permanent magnets disposed at regular intervals along the inside to provide the magnetic poles. The magnetic field sensors are disposed at a distance from each other in the proximity of the periphery to measure the magnetic flux leaking radially through the external rotor from the permanent magnets on the inside.