Model predictive duty cycle control for three‐phase Vienna rectifiers

Abstract

The Vienna rectifiers are widely used in industrial applications. The computationally efficient optimal switching sequence model predictive control directly optimizes the switching sequences. Thus, it requires to store the switching states of 25 voltage vectors, which increases the memory usage. Moreover, the neutral-point (NP) voltage is regulated by redundant vector preselection. As only one redundant vector is applied during the whole sampling period, the NP voltage ripple is relatively large, and the grid current performance is still not satisfactory. To overcome these drawbacks, this paper proposes a model predictive duty cycle control strategy for three-phase Vienna rectifiers, which directly optimizes three-phase duty cycles. The three-phase duty cycles are first obtained by predicting the effects of three-phase duty cycles on instantaneous current variations and minimizing a cost function. To guarantee the grid current performance, a novel three-phase duty cycles modification method is proposed by considering the structural characteristics of the Vienna rectifier. To suppress the NP voltage ripple, the obtained three-phase duty cycles are further optimized. With the proposed method, low memory usage, low harmonic distortion in the grid current, and low NP voltage ripple are achieved simultaneously. Experiments are conducted to verify the effectiveness of the proposed method.