Feedback loop analysis for AC/DC rectifiers operating in discontinuous conduction mode

High power factor rectifiers employing converters operating in discontinuous conduction mode (DCM) exhibit "automatic" current shaping and use output voltage feedback to regulate the output voltage. Analysis of this feedback control loop requires derivation of the control-to-output transfer function in the presence of the rectified AC source voltage. In this paper, linear, line frequency averaged control-to-output transfer functions are derived for some common DCM power converter based rectifier topologies. Also, a new control scheme is analyzed which provides open loop correction for the nonideal input current of the DCM boost power converter, giving it unity power factor. Finally, a simple method of providing "fast" output voltage regulation under transient conditions is introduced.