A Generalized Control Strategy Based on Circuit-Level Decoupling Concept for Vienna Rectifier under Grid Unbalance

In this paper, a generalized discontinuous modulation strategy based on circuit-level decoupling concept (GCLD-DPWM) is presented for Vienna rectifier under unbalanced grid condition. The purpose of the proposed control scheme, is not only to sustain the advantages of the conventional method such as switching loss mitigation, reducing the complexity of the modulation strategy and fast processing, but also to ensure a reliable and near unity power factor operation of the rectifier under mains unbalance circumstances. To serve this purpose, a new control parameter has been introduced through which the modulation reference signals are modified according to the grid unbalance percentage. In this way, the flexibility of the system will significantly increase, while the desired control objectives are achieved. The software implementation of the control technique has been carried out on Vienna rectifier under the voltage drops of 20% and 30% in the grid. The dynamic response of unbalanced input is also presented. Simulation results demonstrate the validity of the proposed control scheme in terms of aforementioned advantages.