Design of robust digital controller for interleave PFC boost converter

Improving of power factor and reducing harmonic distortion in electrical instruments are needed. An interleave boost converter is used for an active PFC (Power Factor Correction). In the interleave PFC boost converter, if a duty ratio, 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 interleave 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 at a load sudden change 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.