Modified one-cycle controlled three-phase PFC rectifier under unbalanced input-voltage conditions

The one-cycle control (OCC) strategy used in the PFC circuit is widely researched because of simple circuit and needless of the multiplier and sampling input voltage. The output voltage of three-phase PFC converter would contain low frequency ripple whose frequency is twice that of the rectifier's input source voltage under unbalanced input voltage conditions. This ripple signal would cause the input current containing a large amplitude of three-order harmonic component under the OCC control strategy and the THD (total harmonic distortion) of input currents would be increased. The input and output characteristic of OCC three-phase PFC converter is detailed analyzed in this paper, and the resonant is proposed to introduce in the conventional OCC control strategy for restraining the three-order harmonic component which exists in the input currents under the unbalanced input voltage conditions. The design of resonant and system control transfer function is also shown in the paper. At last, the effectiveness of proposed new control strategy to reduce the OCC three-phase PFC rectifier's input current THD under the unbalanced input voltage is verified by simulation and experimental results.