This paper presents a new control method for paralleling single-phase power factor corrected ac-dc converter modules with two power conversion stages. The control algorithm varies the number of converter modules in operation and their power sharing in accordance with the load power demand. This control method offers advantages such as tight output dc voltage regulation, very low output voltage ripple, inherent input power factor correction, flexibility to expand power capability, and high overall efficiency. The paper presents the topological composition of the ac-dc converter module. The principle of operation of the new control method is explained. Simulation results are presented. The results demonstrate that the proposed topology and control method are able to produce tight regulation and good transient response. © 2007 IEEE.