A Dual-DC-Port Rectifier With Active Power Ripple Suppression Under Unbalanced Grid Conditions

The active power decoupling technique is an attractive solution to deal with dual-frequency power ripples in three-phase grid-connected rectifiers under unbalanced grid conditions. However, this technique typically employs extra components and introduces increased power losses. In view of this, this article proposed a dual-dc-port rectifier with active power ripple suppression, which enables direct power delivery among the ac grid and dc ports without additional components and intermediate power conversion. Besides, an equivalent two-level framework is put forward to decouple the controller design for this high-integrated topology. With the proposed equivalent two-level model, the controller design for the dual-dc-port rectifier can be simplified, where the grid current control is achieved by regulating the active vector, and power ripple suppression is realized by allocating the zero vector. Consequently, the proposed active power ripple suppression scheme simultaneously achieves sinusoidal grid currents on the ac side and constant dc output voltage on the dc side because the active power ripples on the ac side are all distributed into the extended power decoupling port on the dc side. Experimental results verify the effectiveness of the employed topology and the designed control scheme.