Patent ID: 7102325

Claim:
A method for determining the rotor flux vector of an electrical machine, characterized by controlling the electrical machine with an inverter, forming an equation for the reactive power (Q inv ) at the output of the inverter, forming an equation for the consumed reactive power ({circumflex over (Q)} mot ) in the electrical machine, forming a reactive power balance equation (Q err ) between the reactive power (Q inv ) at the output of the inverter and the reactive power ({circumflex over (Q)} mot ) consumed in the electrical machine, determining the stator resistance ({circumflex over (R)} s ) of the electrical machine from the balance equation (Q err ) determining the stator flux estimate ({circumflex over (ψ)} s ) using the determined stator resistance ({circumflex over (R)} s ) and the balance equation (Q err ) and determining the rotor flux estimate ({circumflex over (ψ)} R ) using the determined stator flux estimate ({circumflex over (ψ)} s ).