Parameter identification for induction machines

A control apparatus for an electric drive configured to determine and store a control parameter for a vector control in a start-up phase, and to use the stored control parameter for the vector control after completion of the start-up phase, wherein the vector control determines the control parameter for the vector control by

• applying, in a first measurement step, a rotating current indicator to the three-phase winding connections and orienting the electric machine such that an exciter current in a q-axis adopts a minimum value;
• short-circuiting, in a second measurement step, when a rotor of the electric machine is stationary, a field winding of the electric machine and applying to the three-phase winding connections a current indicator in form of a binary noise signal;
• measuring, at three-phase winding connections, a d-component and a q-component of a stator voltage and of a stator current;
• determining from the measured d-component and the q-component of the stator voltage and of the stator current as a first control parameter a stator impedance;
• generating the binary noise signal using a pseudo-random number sequence produced with a feedback shift register having a shift clock, with different predeterminable frequency spectra being generated with a plurality of shift clocks.

An electric drive, comprising

• an electric machine,
• a frequency converter, and
• a voltage measuring apparatus and a current measuring apparatus arranged in an electrical connection between the frequency converter and the electric machine,
• wherein the frequency converter has a control apparatus for the electric drive configured to determine and store a control parameter for a vector control in a start-up phase of the electric drive, and to use the stored control parameter for the vector control after completion of the start-up phase, wherein the vector control determines the control parameter for the vector control by
• applying, in a first measurement step, a rotating current indicator to the three-phase winding connections and orienting the electric machine such that an exciter current in a q-axis adopts a minimum value;
• short-circuiting, in a second measurement step, when a rotor of the electric machine is stationary, a field winding of the electric machine and applying to the three-phase winding connections a current indicator in form of a binary noise signal;
• measuring with the voltage measuring apparatus and the current measuring apparatus, at three-phase winding connections, a d-component and a q-component of a stator voltage and of a stator current;
• determining from the measured d-component and the q-component of the stator voltage and of the stator current as a first control parameter a stator impedance;
• and
• generating the binary noise signal using a pseudo-random number sequence produced with a feedback shift register having a shift clock, with different predeterminable frequency spectra being generated with a plurality of shift clocks.