Implementation of single-phase switching mode rectifier with three PWM control schemes

A novel, single-phase switching mode rectifier is proposed to achieve the bi-directional power flow, regulate de bus voltage, reduce line current distortion and obtain nearly unity power factor. Based on the neutral point clamped topology, the voltage stress of the power devices is clamped to half dc bus voltage instead of full dc link voltage in the conventional PWM rectifier. In the proposed control scheme, the line current tracking, dc link voltage regulation and neutral point voltage compensation are performed by the inner loop current controller, the outer loop voltage controller and voltage balance compensator, respectively. Three PWM operation approaches are used to generate bipolar PWM, unipolar PWM or three-level PWM voltage waveform on the ac terminal of the proposed rectifier. The validity and effectiveness of the proposed control techniques are verified by the experimental results.