Full Power Range Seamless Control of Three-Phase Unidirectional Vienna Rectifier including Partial DCM/CCM Operation with Low Harmonic Current Distortion even under Highly Distorted Grid

Control of unidirectional three-phase Vienna Rectifier is somehow easy in the continuous conduction mode (CCM) range. As the input current is decreasing, the converter starts entering into the discontinuous conduction mode (DCM) region for a portion of the current period, i.e. around zero crossings, until full DCM operation is reached at very low current levels. Some control issues arise in the transition and in the full-DCM range region, and lower current quality is normally experienced within these operating ranges. In this paper a novel method to allow a full power range seamless control within the different operating ranges is proposed. A high quality of the input current is attained even under highly distorted input voltage and seamless control of the converter is guaranteed, ranging from full DCM to the transition region to full CCM operation. Theoretical analysis, simulations and preliminary experimental results based on a custom-designed industrial converter are reported to prove the effectiveness of the proposal.