Circuit theory of power factor correction in switching converters

This paper discusses the circuit theory aspects of power factor correction in switching converter circuits. The discussion begins with an examination of the requirement of power factor correction in dc/dc converters. Using the concept of zero-order converter circuits, sufficient conditions for a dc/dc converter circuit to provide power factor correction are derived. The duality principle is applied to generate new converter circuits that can achieve power factor correction. The practical application of power factor correction is considered in conjunction with the requirement of tight output voltage regulation. Detailed study of the circuit configuration that can simultaneously provide power factor correction and output regulation is given. Based on a general three-port model, the voltage regulator with power factor correction capability is studied in terms of the power flow between the input port, output port and energy storage port. A detailed consideration of the power flow among the three ports leads to the derivation of all possible minimal configurations that can achieve power factor correction and voltage regulation. The efficiencies of these minimal configurations are studied theoretically, leading to the concept of 'reduced redundant power processing' which provides important clue to efficiency improvement. Another issue addressed in this paper is the synthesis of practical circuits that can provide power factor correction and output regulation. In particular, four practical minimal configurations that achieve reduced redundant power processing are considered. A systematic synthesis procedure is derived for creating converter circuits that achieve power factor correction and output voltage regulation. The control issue is also investigated in depth, pinpointing the basic requirement on the number of control parameters needed and its relationship with the operating mode. Copyright (C) 2003 John Wiley Sons, Ltd.