The AC-DC Stage: A Survey of Structures and Chopper Control Modes for Power Factor Correction

AbstractOver the last few years, power factor correction has become an important field of research, due mainly to changing low frequency EMC standards. Our interest lies in AC/DC conversion from 230 V line voltage. Since July 1 1995 and for this type of line, European standard EN 61000-3-2 has replaced EN 60555–2, which entails great change for low and medium power converters.Usually, the stage between the network and a DC/DC converter is composed of an uncontrolled diode rectifier followed by a structure comprising at least an inductor and a capacitor. First, the capacitor sets the voltage variation in primary DC voltage and the inductor induces the input current waveform. However, these characteristics are not controlled by the typical rectifier and depend on network conditions or on load variations. This low-cost robust system is analysed respecting EN 60555–2 and EN 61000-3-2 criteria. The relation between total harmonic distortion and the power factor is shown.In order to improve the behaviour of thi...