Method of determining the position of the drive mechanism of an electric machine, such as a motor, from the current supplied, and arrangement for carrying out the method

An arrangement for an improved measurement of the position of a drive mechanism of an electric machine from the current supplied to the electric machine, wherein the measurement is effected over two paths or channels that are independent of one another to obtain two measured values, and wherein thereafter the two measured values are combined and are cross checked with respect to a safe manner of operation or positioning of the drive mechanism, comprising:

• a circuit configured for determination of the position of the drive mechanism in one of the channels;
• a sensor disposed in the circuit and configured to measure a three-phase current of the electric machine to obtain measured values;
• a converter following said sensor in the circuit and configured to convert the measured values of the three-phase current to a current space vector;
• a computing unit following said converter in the circuit and configured to calculate the angle of the current space vector within one electrical revolution and to determine the position of the drive mechanism;
• and
• a current regulator having an addition or summing unit configured to add, within the electric machine, a current command having a field that acts in the direction of a flux or field of the drive mechanism.