Single-phase high power factor rectifier with asymmetrical legs

In this paper, a single-phase switching mode rectifier is presented to improve the power factor, reduce current harmonics and regulate dc bus voltage. Six active switches are used in the proposed rectifier to achieve the three-level pulse-width modulated operation. Two rectifier legs are used in the adopted rectifier. The rectifier leg-a is operated at the carrier frequency and rectifier leg-b is operated at the line frequency. With appropriate control scheme, three voltage levels and two voltage levels are generated on the rectifier leg-a and leg-b, respectively. Two control loops are adopted in the control scheme to achieve line current command tracking and dc-link voltage regulation. A neutral point voltage compensator is adopted in the system to balance the capacitor voltages on the dc side. Based on the proposed control scheme, a three-level pulse-width modulated waveform is generated on the ac terminal of the rectifier. Experiments are provided to verify the performance of the control scheme.