New single-phase power factor correction topologies with high efficiency and wide input voltage ranges

Abstract

Due to the standards such as IEEE 519 and IEC 61000 imposing a limit on harmonic current drawn by equipments, it is necessary to develop an power system whose AC line is low in harmonics and power factor is close to unity. To cope with these limitations, many power factor correction converters employing a boost topology at their input stage has been proposed and these can be divided into two kinds of approaches: the two stage approach and the single stage approach. Despite the two stage approach has a number of good electrical characteristics, it is not desirable to use in low power level applications since it is bulky and costly. Therefore, simple low power level power factor correction converters should be developed. Based on forward topology, a single stage AC/DC converter for low power level applications operating in discontinuous conduction mode(DCM) is proposed. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulations. This converter also achieves a high efficiency by employing an active clamp method and synchronous rectifiers. However, this topology has a disadvantage that the switch voltage stress is heavy at light load which is the general characteristic of DCM topologies. To overcome this advantage, a single stage AC/DC converter based on a half bridge topology is developed. An asymmetrical control to achieve a soft switching of switches is adopted in this topology. Synchronous rectification method is also employed to reduce the rectification loss. The modelling and detailed analysis of theses proposed topologies are performed to derive the design equations. Based on these design equations, a 90W prototype converters have been designed and experimented. These prototypes meet the IEC 61000-2 regulations satisfactorily and have a high efficiency. Furthermore, since a large 120Hz ripple are not shown in the output voltage, a wide bandwidth output voltage controller can be ...