A power factor analysis of the input part of an advanced AC/DC/AC converter for variable speed wind turbines is presented. Two types of rectifying input converters are compared: the boost rectifier, consisting of three AC inductors, a three-phase diode bridge and a switching element to obtain voltage boost chopper behavior; and a conventional diode bridge rectifier, followed by a voltage boost chopper. Most of the analysis is focused on the boost rectifier analysis, of which the power factor and the distortion factor are derived. It follows that for a synchronous generator without damper windings, the boost rectifier seems a good solution for both a high power factor (maximally 0.955) and voltage (boost) control capability. For a synchronous generator with damper windings, however, the conventional diode bridge rectifier, followed by a voltage boost chopper, yields the best power factor. For the boost rectifier, an analytical expression for the chopper switch current demand as a function of the AC power demand and generator rotational speed is given. 13 figs., 1 tab., 1 app.