Analysis and Design Considerations of Improving Power Factor at Light-Load in a CHB Rectifier with Common-Duty Control

Multi-level CHB rectifier with common-duty-ratio control suffers from low power factor in light-load condition, which related to small boost inductance and insufficient gain of current compensator at line-frequency. In order to solve this problem, a practical design method based on proportional resonant compensator is proposed, which can realize the optimization of power factor under light load. Finally, the effectiveness of the design method is verified by experiments, and the light-load power factor of CHB rectifier is increased to 0.95.