AFE Rectifier Control Based on Virtual Flux Direct Power Control and Power Ripple Elimination Under Unbalanced Network Condition

Among different active front end (AFE) rectifier control methods, model predictive direct power control (MPDPC) is one of the appropriate and effective one. This method chooses best switching state based on simple calculation of converter behavior due to consideration of all possible switching states. MPDPC present good performance in balanced network condition and can control AFE rectifier with sinusoidal input currents and unity power factor. However, in the network unbalanced condition, the MPDPC shows harmonics and disturbance in the current waveform. It's almost impossible to achieve unity power factor and sinusoidal input current waveform of AFE rectifier in the unbalanced and harmonized supply condition. A new method which is the combination of the virtual flux and MPDPC with active power ripple elimination is proposed in this paper. This method uses new approach to eliminate the active power pulsation based on calculated virtual flux. Furthermore, a new current prediction method based on the virtual flux technique is proposed. This method has the advantages of VF and MPDPC techniques at the same time. Control of AFE rectifier with sinusoidal input currents, unity power factor, high robustness in high percentage of unbalance, simple calculation under unbalanced and harmonized condition of the network are some advantages of the proposed method. Unlike the conventional methods, there is no need for the positive and negative sequences extraction which is a complex calculation. Simulation and experimental results are presented to confirm the effectiveness of the proposed method.