Direct Digital Control Applied to T-type Vienna Rectifiers for Power Factor Correction

This paper develops a three-phase three-wire T-type Vienna rectifier with direct digital control (DDC) for power factor correction (PFC). It features lower component voltage stress, reduced input current harmonics, boost-type topology, and higher power density. The DDC strategy is adopted to simplify the derivation of control laws through a division-summation process. This control method does not need abc-to-dq frame transformations; thus, it results in a simple derivation and programming. Furthermore, not only can the control laws handle the normal input voltage, but they can handle imbalance and distortion conditions. The successful control of three-phase decoupling is achieved, making the rectifier more effective. Experimental results from a 6 kW prototype verify the analysis and discussion.