Approximate 2-Degree-of-Freedom control for interleaved PFC boost converters

Making power factor and harmonics distortion of power supply better are needed. An interleaved boost converter is used for an active PFC (Power Factor Correction) for reducing ripples. In the PFC boost converter, if a duty ratio, a load resistance and an input voltage are changed, the dynamic characteristics are varied greatly. This is a prime reason of difficulty of controlling the PFC boost converter. In this paper, a robust digital controller of the interleaved PFC boost converter using an A2DOF (Approximate 2-Degree-Of-Freedom) method for keeping up high power factor and low harmonics against any load is proposed. Experimental studies using a microcontroller for the controller demonstrate that this type of digital controller is effective to improve power factor and to suppress the output voltage variation.