Sensorless rotor position measurement in electric machines

DETAILED DESCRIPTION According to the invention a position sensing system for an electric machine with one or more phases, comprises at least one current transducer arranged for measurement of the current in a monitored phase winding, means for deriving a measurement of the magnetic flux linking said monitored phase winding, and control means operable to measure, for the monitored phase winding, said current and flux simultaneously at a predicted position of a reference rotor angular position, the angular error between said predicted position and an actual reference angular position being determined by a comparison of the measured current and flux with the expected current and flux at the actual reference position.