New PFC design using Multiple Buck Converters

Abstract

This paper presents a new design of a power factor correction (PFC) technique with a step down dc-dc buck converter. This research proposes PFC that adopts voltagecontrolled parallel-connected buck converters. The parallel connection structure increases the power level, enhances the overall efficiency and power system reliability. However, unequally current distribution between converters is a major problem which may lead to inductor saturation and even destroy the converters which handles the larger current. For this reason, a suitable control scheme used to overcome this issue.A suitable control scheme is suggested for the parallel connected buck converters. An average control scheme is suggested for the PFC system. In this scheme, the output current of each converter tracks the average load current which is the ratio of the load current to the number of parallel-connected converters. This scheme is a modular but needs only one information which is the number of parallel-connected converters to be shared between converters. A mathematical analysis is performed to examine the system performances including current distribution between the parallel-connected converters and stability of proposed PFC. The analysis reflects the system stability and shows the possibility of maintaining even current distribution between the converters. A Simulation results show the excellent performance of the PFC with an equally current distribution between converters.