Patent ID: 8737103

Claim:
A method for controlling a converter, wherein the converter is configured for generating an AC current for at least two phases by outputting different voltage levels for each phase, wherein the different voltage levels depend on switching states of the converter, the method comprising: (a) generating a first sequence of voltage vectors, each voltage vector including a voltage level for each phase, by (i) generating a reference waveform for each phase, and (ii) determining the voltage levels for a phase for each voltage vector of the first sequence by deriving the voltage levels from the respective reference waveform for the phase; (b) determining a set of equivalent sequences of voltage vectors by: (i) calculating voltage level differences for each voltage vector of the sequence of voltage vectors, the voltage level differences being differences of voltage levels of the voltage vector, (ii) determining an equivalent voltage vector with equal voltage differences, and (iii) generating an equivalent sequence by replacing at least one voltage vector of the first sequence with the equivalent voltage vector; (c) selecting one sequence from the set of equivalent sequences which optimizes an internal state of the converter, when the sequence is applied to the converter; and (d) applying the first voltage vector of the selected sequence to the converter.