Patent ID: 7256561
Filing Date: 2007-08-14
Classification: H02P

Abstract:
1. A method for operating a rotating electrical machine, the rotating electrical machine being connected in terms of phase to a converter circuit, having a DC voltage circuit, for connecting m voltage levels, where m≧2, having the following steps (a) connection of phases of the converter circuit to the DC voltage circuit in accordance with a selected switching state combination of switching states for power semiconductor switches in the converter circuit, wherein the selection of the switching state combination takes place in the following further steps: (b) beginning with a starting sampling time k for a selectable number N of sampling times: (c) formation of switching state sequences for each determined switching state combination at the starting sampling time k, each switching state sequence being an arrangement of determined switching state combinations of the N sampling times next to one another in a row, said switching state combinations being associated with the respective switching state combination at the starting sampling time k, (d) for each of the switching state sequences, calculation of a torque trajectory of the rotating electrical machine and a magnetic stator flux trajectory of the rotating electrical machine from determined state value sets of the rotating electrical machine and the converter circuit for the starting sampling time k up to the sampling time k+N, (e) selection of the switching state sequences in which an associated torque trajectory and a magnetic stator flux trajectory at the (k+N)-th sampling time are in each case within a predetermined value range, or (f) for each of the selected switching state sequences, determination of the number of times n until the extrapolation of the trajectory values of the associated torque trajectory or the trajectory values of the magnetic stator flux trajectory with respect to the (k+N−1)-th sampling time and (k+N)-th sampling time is outside the respective predetermined value range, (g) for each of the selected switching state sequences, determination of the total number of switching transitions s of the associated determined switching state combinations, (h) for each of the selected switching state sequences, calculation of a quality value c from the number of times n and the total number of switching transitions s, (i) setting that determined switching state combination at the starting sampling time k as the selected switching state combination with which the quality value c of the associated selected switching state sequence is at its smallest, (j) repetition of steps (a) to (i), where k=k+1.