Small-signal equivalent circuit models for converters using rectifier control cell

This paper studies the behavior of a combination of a capacitor, a current source, and a diode in the charge-pump power factor correction circuit identified as a converter control device. Circuit-averaging technique is applied to this control device in order to derive its equivalent circuit model. Its model reveals two-terminal characteristic of the device. The small-signal model possesses three circuit elements: two controlled sources and a small-signal resistor. The small-signal model is inserted in the three basic converter topologies, and their control-to-output and line-to-output transfer functions are calculated. The frequency response for boost topologies are analyzed and verified through circuit simulations. The calculated results agree well with those of circuit simulations.