Three-phase four-wire Vienna I rectifier with active filter function including neutral current mitigation

In this paper a Vienna I rectifier is used to achieve active filtering function including the neutral wire current compensation (VR-AF) in a three-phase four-wire system. A linear quadratic with integral action regulator (LQIR) is designed to achieve overall DC bus voltage regulation, harmonics, reactive power and load´s neutral current compensations. The converter model is set in the d-q-o rotating reference frame. The latter is augmented with the integral of the q and o components of the (VR-AF) currents and overall DC bus voltage to achieve integral action. The converter is controlled as a multi-input multi-output (MIMO) system and a fixed PWM at 10 kHz is used to generate the gating signals of the power devices. The system is tested for harmonics, reactive power and load unbalance compensation for balanced/unbalanced loads. The simulation results obtained with SPS and Simulink of Matlab show good performance in terms of overall DC bus voltage regulation; line currents shaping, balancing and neutral current mitigation which proved the effectiveness of the adopted control strategy.