Patent ID: 8350517

Claim:
A method of connecting a control unit as inverter or converter to an asynchronous machine operated without encoder, the asynchronous machine having stator windings and being rotatable at a mechanical rotary speed, wherein the asynchronous machine is regulated by the control unit, the method comprising: (a) determining a stator current vector from measured currents of the stator windings of the asynchronous machine and a stator voltage vector; (b) calculating a stator flux change vector from the stator current vector, the stator voltage vector and a stator resistance in accordance with a machine model; (c) calculating an angle difference between the stator current vector and the stator flux change vector; (d) regulating the calculated angle difference to a reference value of +90° or −90°, wherein an output signal of an associated regulator corresponds to a rotary field frequency of the stator voltage vector; and (e) regulating an amplitude of the stator voltage vector by way of a current regulator an input thereof being provided with a difference between a current reference value and a value corresponding to the amplitude of the stator current as a regulating difference.