Boost-type power factor correction system with three-level sigma-delta modulation

A boost PFC system using a three-level sigma-delta modulation technique, as an alternative to PWM based methods, is presented. The operating principle is based on proportionality between the average voltage over a switching period of the boost switching node (MOSFET drain), and the average input current, so as to make the input impedance equal to a resistance in the frequency range of interest for the PFC function. The system proposed is the first that can operate under both CCM and DCM conditions maintaining a very low THD. Theoretical results are confirmed by simulations and experimental results on a laboratory prototype