Dead-zone digital controllers for improved dynamic response over wide load range in tri-state boost PFC converter

Converters operating in discontinuous-conduction-mode (DCM) and continuous-conduction-mode (CCM) are suitable for light and heavy loads respectively. A novel tri-state boost PFC converter is proposed in this paper, which benefits with reduced line current harmonics, improved power factor and wide load variation range, while preserves cost, size and fast response advantages of conventional DCM boost PFC converter. The additional degree of freedom introduced by inductor current idling operation state has been exploited through the dead-zone control technique to achieve PFC. The dead-zone can be dynamically adjusted in accordance with output voltage ripple. Analysis and simulation results of the tri-state PFC converter have been presented. The proposed converter shows improved load variation range and dynamic performance under load variation.