Design of approximate 2DOF digital controller for interleaved PFC boost converter

In general, a current conduction mode boost converter is used for active PFC (Power Factor Correction). In a PFC boost converter, if a duty cycle, a load resistance and an input voltage are changed, the dynamic characteristics are varied greatly. This is the prime reason of difficulty of controlling the interleaved PFC boost converter. In this paper, the robust digital controller using an A2DOF (Approximate 2-Degree-Of-Freedom) method for suppressing the variation of output voltage in dynamic load response with high power factor and low harmonic is proposed. Experimental studies using a micro-processor for controller demonstrate that this type of digital controller is effective to improve power factor and to suppress output voltage variation.