Small-Signal Analysis of CPC-Single Stage AC/DC Converter with PFC

An analysis approach of a signal stage AC/DC converter with resonant model PFC and in current-programmed control (CPC) has been investigated in this paper. A small-signal model has been derived to determine the small-signal characteristics of the converter. By employing this model, the following significant features have been revealed or explained: (1). If the artificial ramp slop is properly selected, the ideal line-to-output transfer function of forward converter becomes zero. That is to say, the output voltage fluctuation of causing from a perturbation of the DC bus voltage can be substantially restrained; (2). It has been verified that the substantial damping introduced by CPC leads to essentially a single-pole response in current-programmed control-to-output transformer function. A second pole appears near operating frequency and an approximating formulas as well as the computing method have been given out; (3). The CPC of PFC circuit plays an important role to reduce the DC bus voltage fluctuation causing from line voltage perturbation; (4). The load current perturbation has a little effect on DC bus voltage if D
₁
GtD
₂
for the DCM- boost-PFC converter