Research on a novel three-level PWM rectifier

A novel three-phase three-level asymmetry-arm neutral-point-clamped switching mode PWM rectifier is proposed, the mathematical model and working mode of the rectifier are derived, and the fixed frequency control scheme is analyzed in detail. Two control loops are used in the proposed control scheme. In the outer control loop, a proportional integral voltage controller is used to regulate the dc-link voltage. A phase lock loop circuit is adopted to generate a sinusoidal waveform in phase with mains voltage to achieve power factor correction. In the inner control loop, a carrier-based current controller is used to track the line current command. The simulation results show that the harmonies is suppressed effectively, unit power factor is achieved, and bidirectional flowing of the energy is implemented.