High power factor single-phase neutral point diode clamped rectifier

A control scheme for the single-phase neutral point diode clamped rectifier is proposed to achieve unity power factor, balanced neutral point voltage and constant DC bus voltage. Four power switches are used in the proposed rectifier to generate a two-level unipolar PWM or three-level PWM waveform on the rectifier terminal voltage. The hysteresis current control scheme is used to track the line current command in phase with mains voltage. To balance the neutral point voltage, a capacitor voltage compensator is employed. The effectiveness of the proposed control algorithm was verified by the computer simulations and experimental tests from a laboratory prototype.