Switching Loss-Reduced Space-Vector DPWM for Three-Phase Vienna Rectifier Considering Neutral-Point Voltage Fluctuation

Discontinuous pulsewidth modulation (DPWM) has found widespread application in three-level ac/dc converters due to its superior efficiency. However, conventional DPWM, characterized by low-frequency neutral-point (NP) voltage fluctuations, introduces vector synthesis deviation and leads to increased low-order harmonics in the input current. In this article, a switching loss-reduced space-vector DPWM (referred to as SSV-DPWM) scheme for the Vienna rectifier is presented to reduce switching loss and mitigate current lower-order harmonics. First, vector diagrams with NP voltage fluctuations are optimally redivided, and based on the opposite effect on the NP voltage, a set of clamping mode combinations considering NP voltage fluctuations to eliminate vector synthesis deviation is proposed. Then, the subsector identification and modulation waves calculation of SSV-DPWM are analyzed in detail, which can reduce the digital computation burden. Finally, the proposed SSV-DPWM is validated by a three-phase Vienna rectifier experimental platform, presenting its merits of low switching loss, high efficiency, and reduced current low-order harmonics, even when facing smaller dc-link capacitances.