PROCESS AND DEVICE FOR ELIMINATION OR REDUCING HARMONICS AND/OR RESONANCE OSCILLATIONS

摘要

Process and device for eliminating or reducingharmonics and/or resonance oscillationsAn a.c. machine (7) with, connected in parallelthereto, a capacitor bank (CR, CS, CT), which are fedby a converter (1 - 4) with a d.c. intermediatecircuit, form a resonant system which is excited by therectangular current of an inverter (4) of theconverter. In this case, there is superimposition of thefundamentals and the normal harmonics in the machinevoltage and in the machine current of an additionalharmonic with the frequency of the resonance point. Inthe lower speed range of the a.c. machine (7), thisexcitation is eliminated by an optimum operatingsequence of current gaps, which are generated inside acurrent block by means of a quenching circuit (3).Current gaps are generated at the start and end of eachcurrent block for the purpose of damping the 11th and13th harmonic, and in the middle of the current blockfor the purpose of damping the 7th harmonic. A turn-onangle basic value signal (.alpha.M) is modified by a turn-onangle differential signal (.DELTA..alpha.M) for the purpose ofdamping the 5th harmonic, in particular an exciting oravailable harmonic being controlled to 0 or in thevicinity of 0.