Determination of the position of the rotor of an electric machine

An electrical drive comprising an electric machine and a frequency converter connected to the electric machine, the electric machine comprising a machinery brake for preventing movement of a rotor, the electrical drive comprising a control of the machinery brake;

• wherein the frequency converter comprises:
• a load bridge and a control of the load bridge for supplying electricity between the load bridge and the electric machine connected to the load bridge,
• a determination for at least one electrical parameter of the aforementioned electric machine, and
• a determination for a position of the rotor of the aforementioned electric machine;
• wherein the machinery brake of the electric machine is during the determination of the position of the rotor controlled to prevent movement of the rotor,
• wherein the load bridge is fitted to supply to the electric machine a first, essentially sinusoidal alternating electricity excitation signal, having an essentially constant amplitude, and being essentially continuous in term of its fundamental wave,
• wherein the first alternating electricity excitation signal is formed as a function of the electrical angle reference θ of the electric machine, by changing the value of the electrical angle reference θ,
• wherein the frequency converter is fitted to determine as another function of said electrical angle reference θ the first alternating electricity response signal corresponding to the first alternating electricity excitation signal, and
• wherein an initial angle of the rotor is determined on the basis of the first alternating electricity response signal.