Novel single-phase AC/DC converter with two PWM control schemes

A novel single-phase ac/dc converter with two pulsewidth modulation (PWM) schemes is proposed to draw a sinusoidal line current with nearly unity power factor, achieve balanced neutral point voltage and regulate the de bus voltage. With the aid of neutral point clamped scheme, a three-level voltage pattern is generated on the ac side of the proposed rectifier. To track the line current command derived from a voltage controller and a phase-locked loop circuit, a hysteresis current control scheme is used in the inner loop control. A capacitor voltage compensator is employed to achieve the balanced neutral point voltage. To investigate the effectiveness of the proposed control scheme, the simulation and experimental results based on a laboratory prototype circuit are performed.