Control and Modeling of Boost PFC for the 47~800Hz universal grids

Conventional dual-loop control scheme with the outer voltage loop and inner average current loop is inadequate for the universal 47~800Hz grids due to limited tracking speed and accuracy of the inner current loop. To alleviate this problem, a simple and effective method is demonstrated in this paper, which essentially removes the inner current loop, and the duty cycle required for shaping the input current is calculated in real time. Mathematical analysis and small-signal modelling is further proposed, which verifies that the method is particularly suitable for high-grid-frequency and fast dynamic applications. Other properties, like maximum transfer power, and auto over-load limiting are further discussed. Experimental results from a 700W half-brick PFC module are presented to validate the theoretical analysis.