Multistage Active-Clamp High Power Factor Rectifier with passive lossless current sharing

A new method to design active power-factor-corrector for high-power applications is introduced in this paper. It consist in using the high input impedance of active clamp boost converters in order to make easier the parallel connection of power stages. Experimental results are presented, taken form a three stages laboratory prototype rated at 0.35 times 3 kW, input AC voltage of 230 Vrms, output voltage of 400 V, and 120 kHz switching operation. Due to the simplicity of the current share technique, the control can be done using analog control based on the Unitrode´s UC3854 strategy.