| abstract |
A method and apparatus for reducing current harmonics at harmonic frequencies of a fundamental frequency (f 0 ) caused by an AC / DC converter (2) switchable to a polyphase system (1), comprising the steps of: detecting (S1) a voltage angle (θ) and phase currents (I a , I b , I c ) of the polyphase system (1); Calculating (S2) a fundamental space vector (RZ 0 ) for the fundamental frequency (f 0 ) of the measured phase currents (I a , I b , I c ) on the basis of the detected voltage angle (θ); Calculating (S3) further space vectors (RZ i ) for harmonic frequencies (f i ) of the measured phase currents (I a , I b , I c ) on the basis of harmonic multiples of the detected voltage angle (h · θ); Adding (S4) the calculated space vector (RZ 0 , RZ i ) of the fundamental frequency (f 0 ) and the harmonic frequency (f i ) to calculate a sum space vector (SRZ); Generating (S5) PWM control signals as a function of the calculated sum space vector (SRZ) and driving (S6) the AC / DC converter (2) of the polyphase system (1) with the generated PWM control signals. |