Novel Approach to Current-mode Control in DCM/CCM Boundary Boost PFC

Traditionally, DCM/CCM Boundary Boost PFC Converters with current-mode control require line voltage sensing (via a resistor divider) to define the sinusoidal shape of the reference for the inner current loop and a multiplier to adjust the amplitude of this reference to regulate the output voltage. In contrast, using voltage-mode control neither line voltage sensing nor a multiplier is needed. Lower external part count, lower cost of control and lower power consumption (particularly useful when considering no-load conditions) are the resulting benefits. This paper presents a novel approach to current-mode control that changes this paradigm. With the proposed technique the sinusoidal reference of the inner current loop is synthesized with no sensing of the line voltage and in a way that does not require a multiplier to adjust its amplitude. In this way Power Supply Designers can enjoy both the performance of current-mode control and the savings offered by voltage-mode control.