Multifrequency Current Control With Distortion-Free Saturation

Preventing voltage waveform distortion in multifrequency current control during saturated operation is a difficult problem, which so far has been only partially solved. In this paper, a scheme based on the principle of realizable references is proposed. As the converter enters saturated operation, an algorithm recalculates the converter-current reference such that unsaturated operation returns, i.e., the converter-voltage reference does not exceed the space-vector-modulation hexagon. Distortion is thereby avoided, as is integrator windup.