A Hybrid Carrier-Based DPWM With Controllable NP Voltage for Three-Phase Vienna Rectifiers

In this article, a hybrid carrier-based discontinuous pulsewidth modulation (HCB-DPWM) scheme is proposed for Vienna-type rectifiers. By injecting modified zero sequence components (ZSCs), the proposed HCB-DPWM-I scheme solves the issue of alternating input current distortion under unbalanced neutral point (NP) voltage conditions. The proposed HCB-DPWM-II scheme can also active NP voltage balancing control in case of extreme imbalance NP voltages. The flexible transition between the HCB-DPWM-I and the HCB-DPWM-II is also analyzed. Finally, a 10-kW prototype was built to conduct experiments. Experimental results demonstrate that the HCB-DPWM-I can be preferred to run Vienna-type rectifiers without regulating the NP voltage, and the HCB-DPWM-II can balance the NP voltage under severe NP voltage imbalance conditions. Compared with existing DPWM schemes, both the current THD performance and efficiencies can be significantly improved by the proposed HCB-DPWM scheme, especially under unbalanced NP voltage conditions.