DC-Link Current Ripple Reduction Strategy Based on Adaptive Voltage Vector Allocation for Vienna Rectifier

Reducing the ripple current of electrolytic capacitor enhances the reliability and power density of the Vienna rectifier. An optimized modulation strategy based on adaptive voltage vector allocation is proposed, which can significantly reduce the dc-link current ripple in the Vienna rectifier while maintaining a low computational burden. Using an equivalent-circuit model of switching states, we analyze how different voltage vectors affect capacitor currents in the Vienna rectifier and derive the maximum and minimum capacitor currents under the conventional strategy. The proposed strategy selects the voltage vector with a low dc-link current amplitude as the candidate vector and optimizes the switching sequence to ensure that switching actions are the same as those of the traditional strategy. Furthermore, based on the zero-average value of the capacitor current within one switching period, the duty cycles of the voltage vectors are redistributed by adding the zero-sequence component to the phase voltage, thereby reducing the capacitor current ripple. To reduce algorithm complexity, candidate vectors and switching sequences are adaptively selected by constraining the zero-sequence range and adjusting dual carriers. Finally, experimental results on a Vienna-rectifier test platform validate the effectiveness of the proposed strategy.