Self-sensing methods from MEMs to solar aircraft motors

In order to control the speed and/or position of permanent magnet (PM) motors, they require position sensors. Basically, the auto-commutation needs 3 sensors for a 3-phase motor. In micro-motors, as there is no space for the sensors, self-sensing must be used. With big motors, suppression of the sensors enhances the overall reliability. The motor becomes a sensor itself and electromagnetic phenomena are explored to detect the rotor position. These phenomena are magnetic saturation, back-EMF detection, eddy currents and/or magnetic anisotropy. The present paper will describe the technique used to detect the rotor position in micro electromechanical systems (MEMs) and a solar aircraft motor.