The present invention relates to a method for the sensorless electric
measurement of the position of a rotor of a permanently excited
synchronous machine that is fed by a converter, by means of measuring
signals which are sent to an evaluation device that calculates the
electric position of the rotor from the angular dependence of the current
space vector at an impressed stator flux pattern, wherein the distribution
of absolute values of the differential current space vector varies in
approximation in sinusoidal manner with twice the value of the electric
rotor position angle sought. The method of the invention which can be used
in particular in stationary or blocked machines is characterized in that
the distribution of absolute values is produced from respectively two
successive measurements for an almost inversed magnetization, in such a
way that the superposition of the impressed stator flux and permanently
excited rotor flux enables, due to saturation, a distribution of absolute
values of the current space vector with two different maximum values, from
which the electric rotor position angle sought is determined directly and
unambiguously over 360.degree..
